The document analyzes arsenic concentrations in water, soil, milk, and forage samples collected from dairy farms in Comarca Lagunera, Mexico, a region with naturally high arsenic levels. Water samples showed total arsenic concentrations ranging from 7 to 740 μg/L, with 90% as As(V). Soil samples had total arsenic up to 30 μg/g, though extractable arsenic did not exceed 12% of total. Arsenic in alfalfa, a key crop, ranged from 0.24 to 3.16 μg/g, with 40% in roots. Significant correlations were found between water and soil arsenic and between soil and alfalfa arsenic. Milk samples had
This document provides guidance on interpreting compost test results. Key parameters discussed include moisture content, pH and carbonates, organic matter, nitrogen content and forms, carbon-to-nitrogen ratio, minerals, salinity, inert content, density, and respiration rate. Optimal values are given for various parameters depending on the material and intended use. The importance of considering multiple parameters and characteristics together is emphasized over relying on any single value.
Application of colloidal gas aphron suspensions produced from sapindus mukoro...Soumyadeep Mukherjee
This document discusses using colloidal gas aphron suspensions produced from soapnut, a natural surfactant, to remove arsenic from contaminated soil. Soapnut colloidal gas aphrons (CGAs) and solutions were compared to SDS CGAs and solutions for their ability to remove arsenic from soil columns. Soapnut CGAs removed over 70% of arsenic from soil at pH 5-6, while SDS CGAs removed up to 55%. Both CGAs and solutions showed similar performance, but CGAs were more economical since they contain air, requiring less surfactant. The soapnut solution did not interact chemically with arsenic, allowing recovery of the solution and arsenic after removal from
Determination potassium by_ammonium_acetate_extraction_method_zahid_sau_sylhetSyed Zahid Hasan
Determination_potassium_by_ammonium_acetate_extraction_method_zahid_sau_sylhet.
Some picture and data are collected from internet. procedure is in short form so that it can understand easily.
There is no shortcut of success.
Read book first.
A STUDY ON OCEAN ACIDIFICATION DUE TO CARBON DIOXIDE ALONG THE COAST OF VISAK...Soma Sekhar Sriadibhatla
Extensive Data Analytics on samples to understand Ocean Acidification process, a serious damage to ecosystem, increase in production of Carbon dioxide.
The document discusses soil characterization and acidity status in pine plantation forests. It presents results of chemical analyses performed on soil samples from 5 pine plantations containing 22 forest compartments. The key findings are:
1) Soil samples showed high levels of organic carbon (3.7-10%) and generally highly acidic pH, indicating an acidic soil environment dominated by aluminum buffering.
2) Soil pH decreased with increasing forest stand age, with the most decline in the first 20 years of afforestation.
3) Exchangeable acidity levels were slightly higher than exchangeable aluminum, suggesting aluminum is the dominant form of acidity in these soils.
Kate Scow and colleagues assessed phosphorus cycling in agricultural soils using oxygen isotope analysis of phosphate. They took soil cores from organic and conventional crop rotation plots at Russell Ranch that received either organic or mineral fertilizer. Phosphate was extracted from soils using different methods and the oxygen isotopic composition was measured. Results showed higher phosphorus concentrations in the organic treatment soils. Isotopic signatures suggested more recycled phosphorus in the mineral treatment compared to the organic treatment. This study demonstrated the utility of oxygen isotopes of phosphate in distinguishing phosphorus sources and cycling pathways in agricultural soils under different management practices.
Soil parameters, analysis protocols, interpretation, and fertilizer recommend...ExternalEvents
The second lab managers’ meeting of the South-East Asia Laboratory NETwork (SEALNET) took place on 19 - 23 November 2018 in ICAR-IISS (Indian Institute of Soil Science), Bhopal, India.
Drs. Sanjay Srivastava and Pradip Dey, ICAR-IISS, Bhopal, India (1st Day)
Phosphorus speciation in drinking water treatment residualsAlexander Decker
This document summarizes a study that used X-ray absorption near-edge structure (XANES) spectroscopy to analyze the speciation of phosphorus (P) in soils amended with biosolids and drinking water treatment residuals (WTRs). Two incubation experiments were conducted, one using soils from Egypt and one using soils from the United States. The experiments involved amending the soils with varying rates of biosolids and WTRs and analyzing the resulting P species after incubation periods of 60 days and 30 days, respectively. The results from both experiments indicated that the dominant P species formed depended on the soil type and application rates of biosolids and WTRs.
This document provides guidance on interpreting compost test results. Key parameters discussed include moisture content, pH and carbonates, organic matter, nitrogen content and forms, carbon-to-nitrogen ratio, minerals, salinity, inert content, density, and respiration rate. Optimal values are given for various parameters depending on the material and intended use. The importance of considering multiple parameters and characteristics together is emphasized over relying on any single value.
Application of colloidal gas aphron suspensions produced from sapindus mukoro...Soumyadeep Mukherjee
This document discusses using colloidal gas aphron suspensions produced from soapnut, a natural surfactant, to remove arsenic from contaminated soil. Soapnut colloidal gas aphrons (CGAs) and solutions were compared to SDS CGAs and solutions for their ability to remove arsenic from soil columns. Soapnut CGAs removed over 70% of arsenic from soil at pH 5-6, while SDS CGAs removed up to 55%. Both CGAs and solutions showed similar performance, but CGAs were more economical since they contain air, requiring less surfactant. The soapnut solution did not interact chemically with arsenic, allowing recovery of the solution and arsenic after removal from
Determination potassium by_ammonium_acetate_extraction_method_zahid_sau_sylhetSyed Zahid Hasan
Determination_potassium_by_ammonium_acetate_extraction_method_zahid_sau_sylhet.
Some picture and data are collected from internet. procedure is in short form so that it can understand easily.
There is no shortcut of success.
Read book first.
A STUDY ON OCEAN ACIDIFICATION DUE TO CARBON DIOXIDE ALONG THE COAST OF VISAK...Soma Sekhar Sriadibhatla
Extensive Data Analytics on samples to understand Ocean Acidification process, a serious damage to ecosystem, increase in production of Carbon dioxide.
The document discusses soil characterization and acidity status in pine plantation forests. It presents results of chemical analyses performed on soil samples from 5 pine plantations containing 22 forest compartments. The key findings are:
1) Soil samples showed high levels of organic carbon (3.7-10%) and generally highly acidic pH, indicating an acidic soil environment dominated by aluminum buffering.
2) Soil pH decreased with increasing forest stand age, with the most decline in the first 20 years of afforestation.
3) Exchangeable acidity levels were slightly higher than exchangeable aluminum, suggesting aluminum is the dominant form of acidity in these soils.
Kate Scow and colleagues assessed phosphorus cycling in agricultural soils using oxygen isotope analysis of phosphate. They took soil cores from organic and conventional crop rotation plots at Russell Ranch that received either organic or mineral fertilizer. Phosphate was extracted from soils using different methods and the oxygen isotopic composition was measured. Results showed higher phosphorus concentrations in the organic treatment soils. Isotopic signatures suggested more recycled phosphorus in the mineral treatment compared to the organic treatment. This study demonstrated the utility of oxygen isotopes of phosphate in distinguishing phosphorus sources and cycling pathways in agricultural soils under different management practices.
Soil parameters, analysis protocols, interpretation, and fertilizer recommend...ExternalEvents
The second lab managers’ meeting of the South-East Asia Laboratory NETwork (SEALNET) took place on 19 - 23 November 2018 in ICAR-IISS (Indian Institute of Soil Science), Bhopal, India.
Drs. Sanjay Srivastava and Pradip Dey, ICAR-IISS, Bhopal, India (1st Day)
Phosphorus speciation in drinking water treatment residualsAlexander Decker
This document summarizes a study that used X-ray absorption near-edge structure (XANES) spectroscopy to analyze the speciation of phosphorus (P) in soils amended with biosolids and drinking water treatment residuals (WTRs). Two incubation experiments were conducted, one using soils from Egypt and one using soils from the United States. The experiments involved amending the soils with varying rates of biosolids and WTRs and analyzing the resulting P species after incubation periods of 60 days and 30 days, respectively. The results from both experiments indicated that the dominant P species formed depended on the soil type and application rates of biosolids and WTRs.
This document compares analytical methods for determining volatile fatty acids (VFAs) in environmental samples. It finds that direct potentiometric titration provides acceptable accuracy over 97% and precision in the range of 1.8-15%. The distillation method had poor recovery around 53-58% and higher limit of quantification. Spectrophotometric and gas chromatography methods are also evaluated. VFA concentrations can range from parts per million in surface water to thousands of parts per million in landfill leachates. The document explores methods for separating and quantifying VFAs like acetic acid using distillation, titration, spectrophotometry and ion exchange.
new extractants for potassium estimation in soilMiftha Faiz
New extractants were developed for estimating potassium levels in soil studies. Research found that different extractants extract varying amounts and forms of potassium from soils. Ammonium acetate (NH4OAc) is commonly used but does not extract non-exchangeable potassium. Studies evaluated various extractants including NH4OAc, sodium bicarbonate, nitric acid, calcium chloride and found they extracted different amounts of potassium and correlated to varying degrees with plant uptake. Extractants that extracted higher amounts of potassium and correlated best with plant uptake included ammonium lactate, Mehlich 3 and AB-DTPA.
The document analyzes phosphorus speciation in dairy-manure amended soils in Idaho through various methods including sequential extraction, NMR spectroscopy, and XAFS. The key findings are:
1) Phosphorus in the soils is primarily found as calcium-phosphate minerals, though some adsorbed and organic phosphorus species are also present.
2) With increasing manure addition, more phosphorus adsorbs to iron oxides in the soil rather than forming calcium-phosphate phases, likely due to inhibition by organic matter in the manure.
3) The research provides insights into phosphorus behavior in manure-amended agricultural soils and implications for managing dairy waste and nutrient cycling.
Biohydrogenation of unsaturated fatty acidsMevlut Gunal
The biohydrogenation of unsaturated fatty acids like linoleic acid and punicic acid by Butyrivibrio fibrisolvens results in the formation of trans-11-octadecenoic acid. Experiments with deuterium (heavy water) showed that deuterium was incorporated into the cis double bonds that were reduced, indicating stereospecific reduction. This reduction occurs via cis addition to the lower (D) side of intermediates like cis-9,trans-11-octadecadienoic acid. The distribution of deuterium at the reduced carbon atoms suggests that reduction occurs via addition of a proton and hydride ion mediated by an unknown carrier.
1) Investigators developed analytical methods to detect trienone agricultural pharmaceuticals and their photoproducts at low concentrations in the environment.
2) Photolysis experiments showed these compounds transform into more polar and biologically active photoproducts that can revert back to the parent compound.
3) Column experiments demonstrated these photoproducts may have an increased risk of transport compared to the less polar parent compounds.
his study investigated the microbial community in a full scale anaerobic baffled reactor and sequencing batch reactor system for oil-produced water treatment in summer and winter. The community structures of fungi and bacteria were analyzed through polymerase chain reaction–denaturing gradient gel electrophoresis and Illumina high-throughput sequencing, respectively. Chemical oxygen demand effluent concentration achieved lower than 50 mg/L level after the system in both summer and winter, however, chemical oxygen demand removal rates after anaerobic baffled reactor treatment system were significant higher in summer than that in winter, which conformed to the microbial community diversity. Saccharomycotina, Fusarium, and Aspergillus were detected in both anaerobic baffled reactor and sequencing batch reactor during summer and winter. The fungal communities in anaerobic baffled reactor and sequencing batch reactor were shaped by seasons and treatment units, while there was no correlation between abundance of fungi and chemical oxygen demand removal rates. Compared to summer, the total amount of the dominant hydrocarbon degrading bacteria decreased by 10.2% in anaerobic baffled reactor, resulting in only around 23% of chemical oxygen demand was removed in winter. Although microbial community significantly varied in the three parallel sulfide reducing bacteria, the performance of these bioreactors had no significant difference between summer and winter.
This document summarizes a study on the effect of deficit irrigation on soil properties, physiology, and nutrient assimilation of sweet pepper. The study used three irrigation treatments (100%, 90%, and 80% of crop water requirement) in a randomized block design. Data was collected on soil physical and chemical properties, dry matter accumulation, harvest index, and nutrient uptake. The results of the study will help optimize irrigation for sweet pepper crops during times of drought or water abundance.
Environmental risk assessment of Macabalan creek water in Cagayan de Oro, Phi...Innspub Net
Creek water carries both domestic and commercial wastewater consequently draining organic and inorganic pollutants to coastal water. The present study dealt on the environmental risk assessment of creek water stretching in Macabalan-Cagayan de Oro, Philippines. Selected physicochemical analyses of water samples were carried in both temporal and spatial variations. Risk quotient (RQ), water quality index (WQI), and brine shrimp lethality test (BSL) was employed to draw environmental risk estimate. Overall, dissolved oxygen (DO) concentrations were below the standard set regardless of temporal and spatial variations. Both RQ and WQI showed good statuses on creek water quality despite the low DO. The BSLT similarly indicated a higher concentration for LC50 to be established. The study was preliminary and further monitoring may be essential.
This chapter analyzes the chemical composition of saturated paste extracts from soil samples, which reflects the soil solution. The soil solutions were highly acidic, with pH ranging from 4.36-4.91. Major cations were K+, Mg2+, and Al, while major anions were Cl-, F-, and SO42-. Electrical conductivity decreased with increasing forest stand age, indicating declining nutrient availability over time due to leaching. Aluminum concentrations ranged from 1.3-3.7 mg/L. The composition showed a cation excess that may be explained by dissolved organic carbon in the solutions.
Arsenic in food chain and ground water and its mitigation options in West Be...P.K. Mani
This document summarizes arsenic contamination issues in West Bengal, India, with a focus on contamination pathways and mitigation options. It discusses how arsenic enters the food chain through irrigation with contaminated groundwater, accumulating in crops, livestock, and humans. Rice is a particular concern as it is grown under flooded conditions where arsenic is more mobile. The document reviews arsenic chemistry and behavior in the environment, uptake and accumulation in plants, and health effects on humans. It also evaluates various technologies for removing arsenic from groundwater and mitigation strategies within the food chain, such as alternative irrigation sources, crop varieties resistant to arsenic, and organic amendments to soils.
The document describes procedures for using a soil laboratory kit to test soil samples for nitrogen, nitrate, nitrite, ammonium, and pH. Key steps include:
1. Taking soil samples from different depth layers and mixing in separate containers.
2. Weighing 100g samples and adding extraction solution to make suspensions.
3. Filtering the suspensions and using test strips to measure nitrogen forms and pH by comparing colors.
4. Correcting nitrogen measurements based on soil moisture levels to obtain accurate results.
The kit allows quick analysis of nitrogen availability in soil to help determine optimal fertilizer amounts.
Characterization of mining tailings containing sulfides and carbonates applyi...Judson Arantes
Acid mine drainage (AMD) is the process resulting from the oxidation of sulfides exposed to the action of oxygen and water. The characterization of the minerals likely the formation and neutralization of AMD is important for the follow and evaluation of environmental impact. The analysis of X-ray diffraction (XRD) together with the Rietveld method is presented as a promising alternative to favor the identification and quantification of mineral phases. The results of the static test ANC achieved by accounting for carbonates consumed during the test, were correlated with the results obtained by the characterization techniques of X-ray diffraction (XRD) combined with the Rietveld method. The highest concentration of carbonate buffering found in AM2E, which may explain the static test results to be neutralizing for the sample. The major phases identified for both samples were aluminosilicates and quartz, with greater than 70% by weight levels.
Assessment of remediation Potentials of maize (Zea mays) on sites co-contamin...IJAEMSJORNAL
Phytoremediation is a promising technology for the remediation of sites co-contaminated with inorganic and organic pollutants. A pot experiment was conducted to evaluate the remediation potential of Z.mays in soil co- contaminated with Pb and antracene. Pristine sandy loam soils were polluted with Pb chloride salt and antracene at three different levels (50mg/kg of Pb, 100mg/kg of Pb, and 100mg/kg of Pb+100mg/kg of antracene) and laid out in completely randomized design with 3 replicates. Shoot dry matter weight was significantly reduced (p≤0.05) when compared with control treatments by 40% when exposed to100mg kg-1 of Pb. There was a 48% inhibition of shoot dry matter of Z.mays relative to control treatments when 100 mg Pb kg-1 was mixed with 100 mgkg-1 antracene. Root and shoot metal concentration in Zea mays increased with increasing concentration of Pb. The average Translocation Factor (TF < 1 (0.69) obtained suggests that Zea mays predominantly retains Pb in the root portion of the plant. There was a 5% increase in shoot Pb concentration when soil was contaminated with Pb and antracene. The extractable antracene decreased significantly (p≤0.05) in soil planted with Z.mays as well as in pots without maize plant. This accounted for 65 and 72% of antracene dissipation in planted soil and 40-46% dissipation in unplanted soil. This result suggested that Zeamays is a promising candidate for uptake Pb and dissipation of antracene in co-contaminated soils.
Arsenic removal from soil with high iron content using a natural surfactant a...Soumyadeep Mukherjee
This document summarizes a study on removing arsenic from contaminated soil using a natural surfactant extracted from soapnut fruit and phosphate solution. The study found that:
1) A mixture of the natural surfactant and phosphate solution was most effective at desorbing arsenic from the soil, achieving over 70% removal in the pH range of 4-5.
2) Sequential extraction revealed the mixed solution was effective at removing arsenic associated with amphoteric iron oxide forms in the soil.
3) Response surface methodology predicted the mixture could achieve up to 80% arsenic removal when using around 1.5% soapnut and 100mM phosphate at a soil to solution ratio of 1:30
Welcome to International Journal of Engineering Research and Development (IJERD)IJERD Editor
The document presents a study on the adsorption-desorption behavior of Simazine, an anionic herbicide, on six agricultural soil samples. Kinetic experiments showed that adsorption followed first-order kinetics, with rate constants for adsorption higher than for desorption. Adsorption-desorption isotherms were fitted to linear, Freundlich and Langmuir models. Freundlich and Langmuir coefficients indicated moderate affinity of Simazine for soil samples. Hysteresis coefficients revealed irreversible adsorption on the soils. Organic matter was found to influence Simazine adsorption spontaneously through hydrogen bonding or proton transfer.
The document describes a study characterizing a polymetallic concentrate from mining residuals in Portovelo, Ecuador and testing bioleaching using native microorganisms. The concentrate contained high levels of pyrite as well as gold, silver, and other metals. Native microorganisms isolated from mining sites were enriched and identified as Acidithiobacillus ferrooxidans. In bioleaching experiments, the microorganisms effectively solubilized sulfides at low pulp densities, releasing high concentrations of iron and sulfate. However, microbial activity and metal extraction decreased sharply at higher pulp densities, likely due to inhibition. The study suggests bioleaching could help process mining residuals in Portovelo but microbial adaptation to higher densities would be
This document discusses using phosphate oxygen isotope ratios (δ18OP) to better understand phosphorus cycling in agricultural soils. It presents the goals of developing δ18OP as a tracer to identify the bioavailable P fraction in soils and track the long-term fate of externally applied P. It describes sample processing methods, measurement techniques, and initial findings showing transformation of fertilizer P into recalcitrant apatite P pools in agricultural soils. The document concludes that stable isotope labeling and tracking allows a deeper understanding of P sources, transfer, and transformations in natural environments.
11.phosphorus speciation in drinking water treatment residualsAlexander Decker
This document summarizes a study that used X-ray absorption near-edge structure (XANES) spectroscopy to analyze the speciation of phosphorus (P) in soils amended with biosolids and drinking water treatment residuals (WTRs). Two incubation experiments were conducted, one using soils from Egypt and one using soils from the United States. In the Egyptian experiment, different application rates of WTRs and biosolids were added to soils and incubated for 60 days. In the US experiment, soils were amended with various rates of WTRs and biosolids and incubated for 30 days. XANES spectroscopy was then used to identify the chemical forms of P present in the amended soils. The results provided information on
Number one toxic environmental contaminant elementAlexander Decker
This document summarizes an academic article about arsenic contamination of groundwater. It finds that:
1) Arsenic is ranked as the number one toxic environmental contaminant and is commonly found in groundwater in many parts of the world, including parts of India and Bangladesh.
2) Long term exposure to arsenic contaminated groundwater can lead to arsenicosis and various health conditions like skin lesions and cancers.
3) Food sources like rice and fish can also contribute significantly to human arsenic exposure depending on irrigation water quality and environmental conditions.
Encuentro Ciudadano Lagunero, organización de varias agrupaciones civiles, se pronuncia sobre la paradójica situación que prevalece en la región respecto a la Cuenca Lechera más grande de América Latina, comandada por Lala, no obstante que vivimos en un desierto
El presente documento elaborado por Gerardo Jiménez González, muestra un análisis de los procesos de formación del mercado de tierras y aguas, en la Comarca Lagunera, así como las posibles implicaciones ambientales, económicas y socio-políticas en el campo regional.
This document compares analytical methods for determining volatile fatty acids (VFAs) in environmental samples. It finds that direct potentiometric titration provides acceptable accuracy over 97% and precision in the range of 1.8-15%. The distillation method had poor recovery around 53-58% and higher limit of quantification. Spectrophotometric and gas chromatography methods are also evaluated. VFA concentrations can range from parts per million in surface water to thousands of parts per million in landfill leachates. The document explores methods for separating and quantifying VFAs like acetic acid using distillation, titration, spectrophotometry and ion exchange.
new extractants for potassium estimation in soilMiftha Faiz
New extractants were developed for estimating potassium levels in soil studies. Research found that different extractants extract varying amounts and forms of potassium from soils. Ammonium acetate (NH4OAc) is commonly used but does not extract non-exchangeable potassium. Studies evaluated various extractants including NH4OAc, sodium bicarbonate, nitric acid, calcium chloride and found they extracted different amounts of potassium and correlated to varying degrees with plant uptake. Extractants that extracted higher amounts of potassium and correlated best with plant uptake included ammonium lactate, Mehlich 3 and AB-DTPA.
The document analyzes phosphorus speciation in dairy-manure amended soils in Idaho through various methods including sequential extraction, NMR spectroscopy, and XAFS. The key findings are:
1) Phosphorus in the soils is primarily found as calcium-phosphate minerals, though some adsorbed and organic phosphorus species are also present.
2) With increasing manure addition, more phosphorus adsorbs to iron oxides in the soil rather than forming calcium-phosphate phases, likely due to inhibition by organic matter in the manure.
3) The research provides insights into phosphorus behavior in manure-amended agricultural soils and implications for managing dairy waste and nutrient cycling.
Biohydrogenation of unsaturated fatty acidsMevlut Gunal
The biohydrogenation of unsaturated fatty acids like linoleic acid and punicic acid by Butyrivibrio fibrisolvens results in the formation of trans-11-octadecenoic acid. Experiments with deuterium (heavy water) showed that deuterium was incorporated into the cis double bonds that were reduced, indicating stereospecific reduction. This reduction occurs via cis addition to the lower (D) side of intermediates like cis-9,trans-11-octadecadienoic acid. The distribution of deuterium at the reduced carbon atoms suggests that reduction occurs via addition of a proton and hydride ion mediated by an unknown carrier.
1) Investigators developed analytical methods to detect trienone agricultural pharmaceuticals and their photoproducts at low concentrations in the environment.
2) Photolysis experiments showed these compounds transform into more polar and biologically active photoproducts that can revert back to the parent compound.
3) Column experiments demonstrated these photoproducts may have an increased risk of transport compared to the less polar parent compounds.
his study investigated the microbial community in a full scale anaerobic baffled reactor and sequencing batch reactor system for oil-produced water treatment in summer and winter. The community structures of fungi and bacteria were analyzed through polymerase chain reaction–denaturing gradient gel electrophoresis and Illumina high-throughput sequencing, respectively. Chemical oxygen demand effluent concentration achieved lower than 50 mg/L level after the system in both summer and winter, however, chemical oxygen demand removal rates after anaerobic baffled reactor treatment system were significant higher in summer than that in winter, which conformed to the microbial community diversity. Saccharomycotina, Fusarium, and Aspergillus were detected in both anaerobic baffled reactor and sequencing batch reactor during summer and winter. The fungal communities in anaerobic baffled reactor and sequencing batch reactor were shaped by seasons and treatment units, while there was no correlation between abundance of fungi and chemical oxygen demand removal rates. Compared to summer, the total amount of the dominant hydrocarbon degrading bacteria decreased by 10.2% in anaerobic baffled reactor, resulting in only around 23% of chemical oxygen demand was removed in winter. Although microbial community significantly varied in the three parallel sulfide reducing bacteria, the performance of these bioreactors had no significant difference between summer and winter.
This document summarizes a study on the effect of deficit irrigation on soil properties, physiology, and nutrient assimilation of sweet pepper. The study used three irrigation treatments (100%, 90%, and 80% of crop water requirement) in a randomized block design. Data was collected on soil physical and chemical properties, dry matter accumulation, harvest index, and nutrient uptake. The results of the study will help optimize irrigation for sweet pepper crops during times of drought or water abundance.
Environmental risk assessment of Macabalan creek water in Cagayan de Oro, Phi...Innspub Net
Creek water carries both domestic and commercial wastewater consequently draining organic and inorganic pollutants to coastal water. The present study dealt on the environmental risk assessment of creek water stretching in Macabalan-Cagayan de Oro, Philippines. Selected physicochemical analyses of water samples were carried in both temporal and spatial variations. Risk quotient (RQ), water quality index (WQI), and brine shrimp lethality test (BSL) was employed to draw environmental risk estimate. Overall, dissolved oxygen (DO) concentrations were below the standard set regardless of temporal and spatial variations. Both RQ and WQI showed good statuses on creek water quality despite the low DO. The BSLT similarly indicated a higher concentration for LC50 to be established. The study was preliminary and further monitoring may be essential.
This chapter analyzes the chemical composition of saturated paste extracts from soil samples, which reflects the soil solution. The soil solutions were highly acidic, with pH ranging from 4.36-4.91. Major cations were K+, Mg2+, and Al, while major anions were Cl-, F-, and SO42-. Electrical conductivity decreased with increasing forest stand age, indicating declining nutrient availability over time due to leaching. Aluminum concentrations ranged from 1.3-3.7 mg/L. The composition showed a cation excess that may be explained by dissolved organic carbon in the solutions.
Arsenic in food chain and ground water and its mitigation options in West Be...P.K. Mani
This document summarizes arsenic contamination issues in West Bengal, India, with a focus on contamination pathways and mitigation options. It discusses how arsenic enters the food chain through irrigation with contaminated groundwater, accumulating in crops, livestock, and humans. Rice is a particular concern as it is grown under flooded conditions where arsenic is more mobile. The document reviews arsenic chemistry and behavior in the environment, uptake and accumulation in plants, and health effects on humans. It also evaluates various technologies for removing arsenic from groundwater and mitigation strategies within the food chain, such as alternative irrigation sources, crop varieties resistant to arsenic, and organic amendments to soils.
The document describes procedures for using a soil laboratory kit to test soil samples for nitrogen, nitrate, nitrite, ammonium, and pH. Key steps include:
1. Taking soil samples from different depth layers and mixing in separate containers.
2. Weighing 100g samples and adding extraction solution to make suspensions.
3. Filtering the suspensions and using test strips to measure nitrogen forms and pH by comparing colors.
4. Correcting nitrogen measurements based on soil moisture levels to obtain accurate results.
The kit allows quick analysis of nitrogen availability in soil to help determine optimal fertilizer amounts.
Characterization of mining tailings containing sulfides and carbonates applyi...Judson Arantes
Acid mine drainage (AMD) is the process resulting from the oxidation of sulfides exposed to the action of oxygen and water. The characterization of the minerals likely the formation and neutralization of AMD is important for the follow and evaluation of environmental impact. The analysis of X-ray diffraction (XRD) together with the Rietveld method is presented as a promising alternative to favor the identification and quantification of mineral phases. The results of the static test ANC achieved by accounting for carbonates consumed during the test, were correlated with the results obtained by the characterization techniques of X-ray diffraction (XRD) combined with the Rietveld method. The highest concentration of carbonate buffering found in AM2E, which may explain the static test results to be neutralizing for the sample. The major phases identified for both samples were aluminosilicates and quartz, with greater than 70% by weight levels.
Assessment of remediation Potentials of maize (Zea mays) on sites co-contamin...IJAEMSJORNAL
Phytoremediation is a promising technology for the remediation of sites co-contaminated with inorganic and organic pollutants. A pot experiment was conducted to evaluate the remediation potential of Z.mays in soil co- contaminated with Pb and antracene. Pristine sandy loam soils were polluted with Pb chloride salt and antracene at three different levels (50mg/kg of Pb, 100mg/kg of Pb, and 100mg/kg of Pb+100mg/kg of antracene) and laid out in completely randomized design with 3 replicates. Shoot dry matter weight was significantly reduced (p≤0.05) when compared with control treatments by 40% when exposed to100mg kg-1 of Pb. There was a 48% inhibition of shoot dry matter of Z.mays relative to control treatments when 100 mg Pb kg-1 was mixed with 100 mgkg-1 antracene. Root and shoot metal concentration in Zea mays increased with increasing concentration of Pb. The average Translocation Factor (TF < 1 (0.69) obtained suggests that Zea mays predominantly retains Pb in the root portion of the plant. There was a 5% increase in shoot Pb concentration when soil was contaminated with Pb and antracene. The extractable antracene decreased significantly (p≤0.05) in soil planted with Z.mays as well as in pots without maize plant. This accounted for 65 and 72% of antracene dissipation in planted soil and 40-46% dissipation in unplanted soil. This result suggested that Zeamays is a promising candidate for uptake Pb and dissipation of antracene in co-contaminated soils.
Arsenic removal from soil with high iron content using a natural surfactant a...Soumyadeep Mukherjee
This document summarizes a study on removing arsenic from contaminated soil using a natural surfactant extracted from soapnut fruit and phosphate solution. The study found that:
1) A mixture of the natural surfactant and phosphate solution was most effective at desorbing arsenic from the soil, achieving over 70% removal in the pH range of 4-5.
2) Sequential extraction revealed the mixed solution was effective at removing arsenic associated with amphoteric iron oxide forms in the soil.
3) Response surface methodology predicted the mixture could achieve up to 80% arsenic removal when using around 1.5% soapnut and 100mM phosphate at a soil to solution ratio of 1:30
Welcome to International Journal of Engineering Research and Development (IJERD)IJERD Editor
The document presents a study on the adsorption-desorption behavior of Simazine, an anionic herbicide, on six agricultural soil samples. Kinetic experiments showed that adsorption followed first-order kinetics, with rate constants for adsorption higher than for desorption. Adsorption-desorption isotherms were fitted to linear, Freundlich and Langmuir models. Freundlich and Langmuir coefficients indicated moderate affinity of Simazine for soil samples. Hysteresis coefficients revealed irreversible adsorption on the soils. Organic matter was found to influence Simazine adsorption spontaneously through hydrogen bonding or proton transfer.
The document describes a study characterizing a polymetallic concentrate from mining residuals in Portovelo, Ecuador and testing bioleaching using native microorganisms. The concentrate contained high levels of pyrite as well as gold, silver, and other metals. Native microorganisms isolated from mining sites were enriched and identified as Acidithiobacillus ferrooxidans. In bioleaching experiments, the microorganisms effectively solubilized sulfides at low pulp densities, releasing high concentrations of iron and sulfate. However, microbial activity and metal extraction decreased sharply at higher pulp densities, likely due to inhibition. The study suggests bioleaching could help process mining residuals in Portovelo but microbial adaptation to higher densities would be
This document discusses using phosphate oxygen isotope ratios (δ18OP) to better understand phosphorus cycling in agricultural soils. It presents the goals of developing δ18OP as a tracer to identify the bioavailable P fraction in soils and track the long-term fate of externally applied P. It describes sample processing methods, measurement techniques, and initial findings showing transformation of fertilizer P into recalcitrant apatite P pools in agricultural soils. The document concludes that stable isotope labeling and tracking allows a deeper understanding of P sources, transfer, and transformations in natural environments.
11.phosphorus speciation in drinking water treatment residualsAlexander Decker
This document summarizes a study that used X-ray absorption near-edge structure (XANES) spectroscopy to analyze the speciation of phosphorus (P) in soils amended with biosolids and drinking water treatment residuals (WTRs). Two incubation experiments were conducted, one using soils from Egypt and one using soils from the United States. In the Egyptian experiment, different application rates of WTRs and biosolids were added to soils and incubated for 60 days. In the US experiment, soils were amended with various rates of WTRs and biosolids and incubated for 30 days. XANES spectroscopy was then used to identify the chemical forms of P present in the amended soils. The results provided information on
Number one toxic environmental contaminant elementAlexander Decker
This document summarizes an academic article about arsenic contamination of groundwater. It finds that:
1) Arsenic is ranked as the number one toxic environmental contaminant and is commonly found in groundwater in many parts of the world, including parts of India and Bangladesh.
2) Long term exposure to arsenic contaminated groundwater can lead to arsenicosis and various health conditions like skin lesions and cancers.
3) Food sources like rice and fish can also contribute significantly to human arsenic exposure depending on irrigation water quality and environmental conditions.
Encuentro Ciudadano Lagunero, organización de varias agrupaciones civiles, se pronuncia sobre la paradójica situación que prevalece en la región respecto a la Cuenca Lechera más grande de América Latina, comandada por Lala, no obstante que vivimos en un desierto
El presente documento elaborado por Gerardo Jiménez González, muestra un análisis de los procesos de formación del mercado de tierras y aguas, en la Comarca Lagunera, así como las posibles implicaciones ambientales, económicas y socio-políticas en el campo regional.
La a historia del patrimonio cultural ha caminado de manera paralela al proceso de construcción
de la nación. El valor otorgado al patrimonio ha estado orientado por la forma
de construir una región, en la que ha sido necesario elegir formas específicas de incorporación
del pasado al presente. El patrimonio corresponde a esos recursos culturales que representan
la memoria colectiva de las comunidades que dieron origen a una región y un sentido
de identidad y pertenencia a un territorio, sin embargo, las políticas culturales, económicas y
jurídicas, dentro de las posibilidades del desarrollo, han reducido el valor del pasado a lo que
es significativamente necesario para justificar el presente
La presente obra busca difundir y crear conciencia sobre
la problemática del agua en México y el mundo,
con el propósito de fomentar la discusión informada
y la construcción de soluciones. En su elaboración se
han consultado y citado muchas fuentes, tanto gubernamentales
como de organizaciones civiles, académicas
y de investigación. En algunos casos se encontrarán
datos discrepantes entre sí, que fueron incluidos
para dar testimonio de la variabilidad de posturas y de
la información publicada, por lo que deben observarse
las fuentes y hacer un juicio propio. Por lo anterior,
las posturas expresadas y la veracidad de lo citado no
necesariamente está avalado por los patrocinadores o
las organizaciones editoras de la obra.
El sector elegido para el informe de este año, el agua, mostró que en nigún otra área la corrupción afecta de manera tan directa y profunda y la vida y el sustento de miles de millones de personas como lo hace en la prestación de los servicios de agua . El agua es un recurso natural, un producto básico y el fundamento de la vida en nuestro planeta.
La temática que aquí nos ocupa es por demás importante en tanto que se trata de un recurso natural vital, reconocido como un derecho humano (en el caso de México, en el Artículo 4º de la Constitución). Por tanto, el acceso, gestión y usufructo del agua ha sido y seguirá siendo una cuestión central, no sólo para las naciones y sus economías, sino para los pueblos. En ese sentido, se afirma que el agua es un bien y recurso que trastoca tanto la seguridad nacional, como la seguridad ecológica, entendida esta última como la seguridad actual y futura de los pueblos de acceder y usufructuar el líquido en cantidades, frecuencia y calidad suficientes.
Este documento analiza el consumo de energía en el sector de agua potable y alcantarillado y propone políticas regulatorias para mejorar la eficiencia energética de los prestadores de estos servicios en América Latina y el Caribe. Está dirigido a las agencias de regulación sectorial así como todas las demás partes interesadas del sector privado y público.
This document summarizes the results of studies on groundwater arsenic contamination in the district of Rahim Yar Khan, Pakistan. Key findings include:
1) Initial testing of 13 water sources in 2004 found arsenic concentrations between 150-400 μg/l, exceeding WHO limits of 10 μg/l.
2) Additional testing in 2005 of 19,307 water sources by UNICEF found that 9,663 samples (50.05%) had arsenic levels from 20-500 μg/l.
3) Blanket testing of 25,000 water sources across the entire district in 2005 found that 13,440 sources (53.76%) had arsenic above 20 μg/l, indicating a catastrophic level of
Determination of the Optimum Sulphur Fertilizer Rate for Groundnut Production...AI Publications
Laboratory studies and pot Experiments were carried out to determine the optimum sulphur (S)fertilizer rate for groundnut production in selected soils of Benue state using sorption indices. Surface soil samples (0-20 cm) were collected for sorption studies and pot experiments. The sorption study was carried out by shaking known concentrations of S (0, 20, 40, 60, 80, 100 and 120 mgkg-1) with 5g soil sample. The suspension was filtered and the amount of S in solution determined. The amount of sulphatesorbed was estimated as the difference between equilibrium sulphate concentration and initial sulphate added. Data from the sorption study was fitted into the Langmuir and Freundlich sorption equations. Thereafter a pot experiment was carried out with six levels of solution sulphate concentration to determine the optimum S concentration for yield of groundnut and the amount of sulphur fertilizer required to achieve this concentration in the soil under study. Result show that both soils have the capacity to sorb sulphur. The sorption maxima, buffering capacity and binding energy of the soils under study are 70.66 mgkg-1, 15.81mg kg-1, 0.22 dm3 mg-1 and 117.84 mgkg1, 9.83 mg kg-1,0.08 dm3 kg-1 for Aliade and Daudu soils respectively.The highest yield in Aliade soil was obtained with 6 mg kg-1 S while 12 mg kg-1 S gave the highest yield in Daudu soil. Aliadeand Daudu soils would require 57.41 and 23.69 kg ha-1S respectively to maintain 12 mg/kg and 9mg/kg of S in the soil solution. Hence for groundnut production in Aliade soil, 57.41 kg S ha-1 is recommended while for the Daudu soil, 23.69 kg S ha-1 is recommended.
The document describes testing different variables of the Hach Arsenic Test Kit to determine its effectiveness in measuring arsenic concentrations in contaminated soil samples. Soil samples were contaminated with varying levels of arsenic from 1 to 1000 ppm. Testing different masses of soil (0.05g, 0.1g, etc.), concentrations, and reaction times, it was found that using 0.1g of soil and running the test for 45 minutes produced the most accurate and sensitive results up to 250 ppm arsenic. Below this concentration, the kit performed best, while higher concentrations were more difficult to measure precisely.
Nutrient loads and heavy metals assessment along sosiani river, kenya.Alexander Decker
This document summarizes a study that analyzed nutrient loads and heavy metal levels along the Sosiani River in Kenya. Water, soil, and sediment samples were collected from 5 sites along the river and analyzed for nitrates, phosphates, and heavy metals. Nitrate and phosphate levels were found to be below recommended limits. However, concentrations of heavy metals like iron, lead, cadmium, zinc, and copper exceeded Kenyan standards, with zinc levels above WHO standards for drinking water. The study concluded that the river water is not safe for domestic use due to heavy metal contamination.
This document summarizes a study that assessed pollutant levels in Lake Tadie in Mampong Ashanti, Ghana. Water samples were collected from 5 points around the lake and analyzed for physicochemical and biological parameters in a laboratory. The results found that temperature, total dissolved solids, and levels of sulfate, nitrate and phosphate were within recommended limits. However, pH levels and concentrations of iron, lead and fecal coliform bacteria exceeded guidelines. The acidic pH is likely due to runoff of fertilizers and waste from surrounding agricultural and residential areas entering the lake. Overall, the lake water quality has been impacted by human activities in the area.
A monthly water analysis on major rivers and creeks in Legazpi City, Daraga and Manito, Albay. Investigations on pH, Chemical Oxygen Demand, Conductivity, Total Hardness and presence of Chlorides, Carbonates and Bicarbonates are used in the analysis.
Influence of water management on chemical kinetics of soils and rice growthAshutosh Pal
This study aimed to examine the effects of different water management regimes on chemical and physical properties of soils and rice growth and yield. Greenhouse experiments were conducted using soils from various locations in the Philippines. Rice was grown under continuously flooded, saturated, and alternating flooded-dried conditions. Soil properties like pH, nutrients, and redox potential were measured over time. Rice growth parameters and yield were also assessed. The results showed that water management influenced soil properties and rice growth in soil-specific ways. Alternating flooded-dried conditions generally improved yield compared to continuously flooded, but the effects varied between soil types. More research is needed to fully understand how water management impacts soils and rice to optimize practices.
Effect of Temperature and Moisture on Degradation of Herbicide Atrazine in Ag...Agriculture Journal IJOEAR
Abstract— Degradation rate and degraded products, deethylatrazine (DEA), deisopropylatrazine (DIA) and atrazine-2-hydroxy (HA), of herbicide atrazine in agricultural soil were determined by ultra-performance liquid chromatography–mass spectrometry. When treating soils for 60d at 25°C, the degradation rate of atrazine increased with the moisture from 5 to 20%. The degradation was fitted one-order kinetic equation and degradation rate constant (k) and Half-life (T1/2) were obtained. T1/2 decreased by 3–4 folds with the increasing temperature from 5 to 35°C and moisture from 5 to 20%. The species and content of the degraded products increased with the temperature and moisture. When treating soil for 60d, the sum content of three degraded products, DEA, DIA and HA is 3–6.8 times greater than atrazine residue. An updated metabolism pathway of atrazine in soil was presented.
This study analyzed aliphatic hydrocarbons in surface sediments from the Sergipe River estuarine system in Brazil. Aliphatic hydrocarbon concentrations ranged from 9.9 to 30.8 micrograms per gram of dry sediment. Carbon preference index values indicated petrogenic input at two sites, while an unresolved complex mixture was found at seven of the nine sites, suggesting multiple organic matter sources. Overall the results found a mix of natural and anthropogenic hydrocarbon inputs to the sediments, despite petroleum exploration and urban/industrial activities in the region.
Arsenic in Tube Well Water in Six Blocks of Supaul District, Bihariosrjce
An experimental estimation of arsenic in a large number of samples by Field Test Kits and by
Hydride Generation Atomic Absorption Spectrophotometer (HGAAS) was done. Water samples were collected
from the following blocks of Supaul district, viz., Raghopur, Basantpur, Supaul, Nirmali, Saraigarh-Bhaptiyahi
and Triveniganj. The aim of this study was to analyze the total arsenic concentration in tube well water of these
regions at different locations. Twenty water samples were randomly selected from each block (n=120) for the
determination of Arsenic concentration, using Field Test Kits. Few samples (n=11) found with higher
concentration of arsenic, were also estimated and confirmed by HGAAS method for comparative observation.
The maximum concentration of arsenic was found to be 0.10 mg/l by using Field Test Kits method and the
average concentration of arsenic of the selected samples was 0.02 mg/l, whereas around 20% of these tube
wells had arsenic concentration above 0.05 mg/l. It was observed that the results obtained by usingField Test
Kits showed less measurement as compared to those obtained by HGAAS method for the same samples, when
the arsenic concentration measured ≤0.10 mg/l. Arsenic concentration was significantly (p<0.0001) higher in
HGASS results than the value obtained by Field Test Kit method.
This document summarizes a study that evaluated the effects of sugarcane pressmud biocompost and mineral fertilizers on maize growth and soil properties. The biocompost had nutrient contents of 1.8% N, 1.83% P, and 0.9% K. A pot experiment found that biocompost and nitrogen fertilizer increased maize height, dry weight, and nitrogen uptake. Biocompost and fertilizers also increased soil organic matter, phosphorus, and potassium levels. The results indicate that biocompost can be used along with mineral fertilizers to boost maize growth and yields by improving soil quality.
2009 assessment effects of cage culture on nitrogenearambulm3
This document summarizes a study that investigated nitrogen and phosphorus dynamics in relation to fallowing periods for a fish cage farm located in a shallow lake in China. The study analyzed total nitrogen and total phosphorus levels in lake water and sediment during two fish rearing cycles from 2000-2001. Key findings include:
1) Nutrient levels increased more during the first rearing cycle than the second.
2) Impacts were greatest near the cages (underneath and at cage sides), with higher sedimentation of nitrogen and phosphorus observed at cage sides.
3) After 3 months of fallowing, water nutrient levels decreased significantly but sediment nutrient levels remained high, indicating recovery occurs during fallowing
Effects of urea and adult palm fertilizer mixture on the survival and body wall tissues of earthworms.
W. U. Chandrasekera and O. K. I. De SILVA
Department of Zoology, University of Kelaniya, Kelaniya 11600, Sri Lanka
Presented at International Forestry and Environment Symposium 2009 at Department of Forestry and Environment Science, University of Sri Jayewardenepura, Sri Lanka from 18 – 19 December 2009 (Session 7- Biodiversity)
W. U. Chandrasekera and
O. K. I. De SILVA
Department of Zoology, University of Kelaniya, Kelaniya 11600, Sri Lanka
Presented at International Forestry and Environment Symposium 2009 at Department of Forestry and Environment Science, University of Sri Jayewardenepura, Sri Lanka from 18 – 19 December 2009 (Session 7- Biodiversity)
This document summarizes a study on the effects of environmental factors on fungal α-amylase production using cereal processing mill residues as substrates. Key findings include:
- An Aspergillus sp. strain isolated from soil samples showed high amylase production. Wheat bran supported maximum enzyme production among various residues tested.
- Maximum amylase activity was achieved under optimized environmental factors - 60% initial moisture, pH 5, incubation at 30°C, 4ml inoculum volume, and 20g substrate in 500ml flask.
- One-factor-at-a-time experiments revealed initial moisture content, temperature, pH, inoculum level, and substrate-volume ratio significantly influence enzyme yield during
La agricultura y ganadería son importantes para la economía de la Comarca Lagunera, pero su modelo actual basado en el uso intensivo del agua no es sostenible dado la crisis hídrica que sufre la región. Mientras que el gobierno se ha enfocado en mitigar los síntomas de la crisis, no ha abordado sus causas como la sobreexplotación de acuíferos. Los pronósticos climáticos indican un aumento de temperaturas y descenso de precipitaciones que empeorarán la crisis. Para mantener la producción láctea
Este documento discute tres temas principales: 1) La importancia de recuperar la soberanía energética en México para poder racionalizar la generación, distribución y consumo de energía. 2) Cómo los gobiernos neoliberales desmantelaron el sistema energético mexicano y aumentaron la dependencia en combustibles importados. 3) Los desafíos que enfrenta el gobierno actual para reordenar el sistema energético y recuperar la autosuficiencia y soberanía energética del país.
Tras 23 años dedicados a exploración científica de Cuatro Ciénegas, la investigadora Valeria Souza decidió hacer maletas y se marchó. El humedal del lugar se esta secando debido a la sobreexplotación del agua y ella no quiere ser testigo de tal tragedia.
Son mecanismos organizados desde las comunidades y la ciudadanía para diagnosticar la situación del
agua en sus territorios, acordar planes y propuestas
para vigilar e influir en el quehacer gubernamental en
torno a la gestión del agua y su entorno natural. Denuncian corrupción, promueven actos de gobierno a
favor del derecho humano y de los pueblos al agua
fortaleciendo la democracia participativa.
La crisis planetaria del agua, biocampos y la esencia sagrada de la vida: una perspectiva transdisciplinaria y La contaminación en los humedales y la importancia de cuidar el recurso agua.
Este documento presenta una introducción al libro "El Zapotillo y su viraje en la 4T: Voces y reacciones". Resume el contexto del conflicto por el proyecto Presa El Zapotillo y cómo el acuerdo alcanzado en 2021 entre el gobierno federal y las comunidades afectadas generó nuevas reacciones. Incluye 7 capítulos con análisis y perspectivas de académicos, activistas y exfuncionarios sobre las implicaciones de este cambio histórico para Jalisco, Guanajuato y los
Este documento presenta el índice del número 132 de la revista Promotio Iustitiae. El número está dedicado al tema del agua y contiene 17 artículos escritos por autores de diferentes continentes que reflexionan sobre la crisis del agua y su relación con la injusticia social. Los artículos abordan temas como los derechos del agua, los conflictos por el agua, la contaminación, la mercantilización del agua y sus efectos en comunidades vulnerables como los indígenas y campesinos.
Ciencias y Humanidades es una nueva revista de difusión
de la ciencia, mediante la cual el Consejo Nacional de Ciencia, humanidades y Tecnología se propone dar a conocer a la población mexicana los avances en ciencias, humanidades, tecnologías e innovación en nuestro
país. Se trata de acercar el conocimiento especializado y de frontera a un público amplio, atendiendo la falta de vinculación entre
diversas formas y tendencias de la investigación científica y social.
En esta medida, la presente publicación responde a la necesidad de
abrir un espacio de diálogo y análisis crítico para el bien común,
que permita poner en comunicación a investigadores, luchadores
sociales y ambientales, miembros de organizaciones no gubernamentales y artistas –entre sí y con la sociedad– de manera que se
abran vías fecundas para la reflexión colectiva.
El Acuerdo de Escazú es el primer acuerdo regional ambiental de América Latina y el Caribe. Además, es el primero en el mundo en contener disposiciones específicas sobre personas defensoras de derechos humanos en asuntos ambientales.
El Acuerdo Regional sobre el Acceso a la Información, la Participación Pública
y el Acceso a la Justicia en Asuntos Ambientales en América Latina y el Caribe
—o Acuerdo de Escazú— se ha vuelto un instrumento regional vinculante muy
importante para los Defensores de Derechos ambientales, de territorios y de la
naturaleza en México y el resto de países de la región desde su entrada en
vigor.
Este documento presenta el prólogo escrito por Armando Bartra para el libro "¿Tiene futuro la agricultura campesina en México? Políticas públicas para la soberanía alimentaria y el desarrollo rural con campesinos" de Víctor Súarez Carrera. Bartra destaca la trayectoria de más de 30 años de Súarez Carrera trabajando en temas agrícolas y rurales desde diversas posiciones. Señala que los ensayos en el libro analizan las políticas neoliberales aplicadas al campo mexicano y pro
¿Qué sigue?:
El legado de la Conferencia de las Naciones Unidas sobre el Agua
Pedro Arrojo Agudo
Relator Especial de la ONU
sobre los derechos humanos al agua potable y al saneamiento
Existen elementos de la naturaleza y mercancías producidas por los humanos que han marcado los tiempos y que conllevan un distintivo geoestratégico. Más que rescatar a la raptada Helena, los griegos buscaban capturar Troya, situada en la moderna Anatolia, para controlar el paso de las especias y la seda provenientes del Lejano Oriente, en el estratégico estrecho de los Dardanelos: la salida del mar Negro al Mediterráneo. Desde la Iliada hasta hoy, el mar Negro, situado entre los pilares geográficos del Cáucaso y los Balcanes, sigue marcando como nunca el diapasón de los tiempos.
Aglutinando diversos conocimientos el autor comparte estrategias utilizadas por permacultores y agricultores quienes, con el manejo apropiado de sus tierras, el agua de la lluvia y el sudor de su frente, verdaderamente cuidan y promueven el desarrollo del Patrimonio Biológico del planeta, con una agricultura regenerativa que va más allá de la sustentabilidad.
Vivimos en un mundo de agua.
Es el único planeta conocido que está cubierto de una capa acuosa líquida. Océanos, ríos, lagos, humedales, nubes, la mayor parte de sus rasgos superficiales están constituidos por agua.
La vida misma, cuya presencia es intrínseca de La Tierra, se forma, desarrolla y existe merced a la presencia de este líquido imprescindible.
Como dice la introducción de Pautas... El agua es un bien natural común esencial para la vida. Es el elemento que sostiene y articula los procesos ecológicos, ambientales, climáticos y geológicos en los ecosistemas del plantea.
Y como dice una de las autoras, hay que estudiar el agua en forma multifactorial, es decir, desde diversos enfoques...
Es así como en el libro se especifican de forma interdisciplinaria desde el contexto, la regulación, las pautas y el rumbo del agua.
Este documento describe el uso de óxidos como fotocatalizadores para descontaminar el agua de manera más eficiente. Actualmente existen contaminantes persistentes en los recursos hídricos que no pueden eliminarse con tratamientos convencionales. La fotocatálisis, que implica la generación de radicales libres cuando la luz interactúa con un material semiconductor, puede degradar estos contaminantes. Óxidos comunes como el óxido de hierro y el óxido de zinc muestran potencial para funcionar como fotocatalizadores,
El humano genera un impacto directo y negativo en el medio ambiente.
Es importante que se lleven a cabo actividades de conservación y mitigación en las áreas de importancia ecológica
Las actividades humanas, en especial las económicas realizadas durante la época
moderna, denominada Antropoceno por los impactos realizados por el hombre, han tenido,
en muchos casos, un impacto directo y negativo en todos los ecosistemas y en el medio
ambiente en general. Con el fin de detener, y si es posible, revertir los daños que ya se
han producido, es importante que se lleven a cabo actividades de conservación y mitigación
en las áreas de importancia ecológica para que se siga desarrollando la vida de diversas
especies, incluida la humana.
La disponibilidad de agua adecuada y suficiente es un problema que está afectando crecientemente las sociedades humanas contemporáneas. Si bien son los países áridos o semiáridos quienes están sufriendo la carencia o mala calidad del agua en forma más aguda, igualmente las zonas más húmedas pueden experimentar problemas de insuficiencia o contaminación de sus caudales hídricos.
2. 134 I. ROSAS ET AL.
Figure 1. Location of the counties (indicated by number) where dairy farms were sampled (indicated
by circle).
On the other hand, the distribution and fate of this metalloid in the agricul-
tural environment has not yet been evaluated. Therefore the present study was
undertaken with the following objectives:
a) To determine arsenic concentration speciation in water, and to correlate these
levels with the amount of extractable arsenic in soil.
b) To determine the concentration of As in Alfalfa (leaves and roots) and corn’s
silage, considering that these forages are consumed by dairy cattle.
c) To evaluate the As biotransfer factor to milk.
2. Materials and Methods
2.1. S AMPLING
Dairy farms of seven counties located at Durango and Coahuila States, Mexico
(Figure 1), were sampled during 1992, in both rainy and dry seasons. Well-water,
soil, alfalfa (leaves and roots), corn’s silage, and cow’s milk were sampled in six-
teen dairy farms during the first sampling period (April) and in seventeen farms
during the second and third sampling periods (July and October). The samples
were obtained from each as follows:
3. ARSENIC CONCENTRATIONS IN WATER, SOIL, MILK AND FORAGE 135
2.1.1. Well Water
To determine arsenic, 1-L samples were collected in polyethylene bottles, previ-
ously rinsed with 20% nitric acid and deionized water. To determine the physico-
chemical parameters, 1-L samples were also collected in the same way, except that
bottles were not rinsed with nitric acid. Samples were placed into an ice box but
not frozen for transportation to the laboratory.
2.1.2. Forage
Samples of alfalfa (Medicago sativa) crops (roots and leaves) and corn’s silage
were put apart and placed into plastic bags. For the calculation of the As biotransfer
factor to milk, 500 g (fresh weight) of the general dairy cow’s diet were collected
from 5 food containers at each farm (alfalfa, corn’s silage, soybean meal, calcium
carbonate, minerals and vitamins) and transported to the laboratory in plastic bags.
2.1.3. Soils
Soils from alfalfa fields were sampled at 0–30 and 30–60 cm depth and 1 kg from
each level was placed into plastic bags.
2.1.4. Cow’s Milk
Cow’s milk was obtained during the cow’s milking and 1-L was placed into a
polyethylene bottle previously rinsed with 20% nitric acid in deionized water.
2.2. A RSENIC ANALYSIS
2.2.1. Sample Preparation
2.2.1.1. Water. The arsenic (III) was determined by extraction with ammonium
pyrrolidinedithiocarbamate (APDC) and methyl isobutyl ketone (MIBK) following
the method described by Subramanian and Meranger (1981). The total arsenic was
determined in an aliquot of 10 mL acidified with 3 mL of concentrated HCl (Perkin
Elmer, 1979).
2.2.1.2. Forage. In the laboratory, roots were rinsed with tap water and scrubbed
with a laboratory nylon brush until all soil was removed, after they were rinsed sev-
eral times with distilled water and finally with deionized water. Leaves and corn’s
silage were carefully washed with distilled and deionized water. The samples were
dried at 60 ◦ C. Afterwards, were grounded in a blender and 1 g was digested with
5 mL of concentrated nitric and 2 mL of perchloric acids (Perkin-Elmer, 1982).
After digestion, the samples were diluted to 50 mL with 1.5% hydrochloric acid.
2.2.1.3. Soil. Soil samples were dried at 60 ◦ C and grounded in an agate mortar
and passed through a 0.177 mm sieve. To determine total arsenic, 0.1 g of grounded
soil was digested with 20 mL of concentrated nitric acid and 10 mL of 15 N
sulfuric acid, after the oxidation of organic matter was completed and fumes of
4. 136 I. ROSAS ET AL.
sulfur trioxide were produced, the samples were cooled and diluted to 50 mL with
deionized water (Thompson and Thoresby, 1977). For extractable arsenic, 5 g of
soil were extracted by shaking with 20 ml of a mixture of 0.05N HCl + 0.025N
H2 SO4 acids (Kahn et al., 1972; Perkin-Elmer, 1982). The solutions were filtered
and made up to 50 ml with the extracting solution.
2.2.1.4. Milk. Samples of 10 g of raw milk were digested with concentrated
nitric and sulfuric acids and 30% hydrogen peroxide, and diluted to 50 mL with
20 mL of concentrated hydrochloric acid and deionized water.
2.2.2. Analysis
A Perkin-Elmer Model 460 atomic absorption spectrophotometer equipped with a
MHS-10 Mercury/Hydride System and a HGA-2100 graphite furnace was used.
A Perkin-Elmer arsenic electrodeless discharge lamp was used as a light source.
Measurements were made with deuterium background correction.
To determine total arsenic in water, forage, soil and milk, 1 mL of 10% potas-
sium iodide solution was added to 10 mL of sample or an aliquot diluted to 10 mL,
after 60 min, arsenic was determined by the hydride evolution method with sodium
borohydride and the MHS-10 Mercury/Hydride System (Perkin-Elmer, 1979). Cal-
ibration was performed by preparing series of standards adding specific chemicals
from the various matrices. The As (III) was measured by Graphite Furnace Atomic
Absorption Spectrometry (GFAAS) by injecting 20 µL of the MIBK phase into
the graphite tube. The concentration of As (V) in water samples was obtained by
subtracting the values of As (III) from the total arsenic concentrations.
2.2.3. Quality Control
For quality control, the total inorganic arsenic was determined in a Water Pollu-
tion Quality Control Sample supplied by US Environmental Protection Agency,
Environmental Monitoring and Support Laboratory-Cincinnati (WP 476E). The
mean value found was 22.4 ± 2.7 µg L−1 (average of 7 determinations), the
value reported by USEPA was 24 µg L−1 . Forage, soils and milk samples were
spiked with known amounts of arsenic, prepared and analyzed in the same way
that the samples. Recovery in spiked samples ranged from 100–103% for forage,
96–100% for soils (total and extractable arsenic) and 95–106% for milk. For each
group of processed samples, blanks (deionized water and reagents) were included
throughout the entire sample preparation and analytical process.
2.3. P HYSICOCHEMICAL ANALYSIS
2.3.1. Water
The samples were analyzed for pH, SO2− , Cl− , NO− , Ca2+ , and Mg2+ . pH was
4 3
measured using a Philips Model PW 9409 digital pH meter with a combination
glass electrode. Sulfates, Cl− and NO− were determined by ion chromatography
3
5. ARSENIC CONCENTRATIONS IN WATER, SOIL, MILK AND FORAGE 137
with a Perkin-Elmer instrument equipped with a Model 250 Isocratic LC Pump,
a Conducto Monitor III conductivity detector and a strong anion analytical col-
umn Hamilton PRP-X100. Sodium, Ca2+ and Mg2+ were determined by atomic
absorption spectrophotometry.
2.3.2. Soil
Texture analysis was performed by the hydrometer method (Palmer and Troeh,
1980). pH was measured in a slurry (shaking 5 parts of distilled water and 1 part
of soil during 15 min). The organic matter was determined by oxidation of 1 g
of sample with 10 ml of 1 N K2 Cr2 O7 and 20 ml of concentrated H2 SO4 and
titration with 0.5 N FeSO4 .7H2 O and o-phenanthroline as indicator (Palmer and
Troeh, 1980).
2.4. S TATISTICAL ANALYSIS
For the statistical analysis, whenever a value of an element was below detec-
tion limit, the half of the detection limit was used for computation purposes. The
one-way Kruskal Wallis test (one-tail test) was used to compare the arsenic con-
centrations in groundwater, soil, forage, and cow’s milk samples measured at dif-
ferent farms. The relationship between arsenic levels found in soil, forage, milk,
and water were calculated by the Spearman coefficient correlation. The Mann-
Whitney test (two-tail test) was applied to compare the probability of differences
between means of total arsenic concentrations of two soils horizons and washed
and unwashed plants.
The As biotransfer factor (BTF) to milk was calculated using Steven’s equation
(Stevens, 1991):
Concentration of As in milk (mg L−1 )
BTF (day L−1 ) = Mean daily animal intake of As (mg day−1 )
·
Holstein breed: body weight, 600–700 Kg
Animal intake = 10 kg of food (dry matter), 65L water
3. Results
The highest As concentrations were found in the following counties: Francisco I.
Madero with 740 µg L−1 , Tlahualilo, 590 µg L−1 and San Pedro, 490 µ L−1 (Table
I). Ninety percent of the total arsenic was detected as As (V). The Kruskal-Wallis
test (H=23.6, p=0.05) indicated significant differences among the water As levels
measured at the sampled counties. The results of the physicochemical analyses
of the well water samples indicated that the pH ranged from 7.8 to 8.2, but much
higher differences were found among the analyzed ions. Chloride ranged from 21.3
to 87.2 mg L−1 , SO2− from 182 to 428 mg L−1 , Na+ from 34 to 410 mg L−1 , Mg2+
4
from 3.4 to 36.4 mg L−1 and Ca2+ from 29 to 120 mg L−1 (Table II).
6. 138 I. ROSAS ET AL.
Figure 2. Concentrations of total arsenic in 0–30 cm and 30–60 cm soil horizons.
7. ARSENIC CONCENTRATIONS IN WATER, SOIL, MILK AND FORAGE 139
TABLE I
Statistical summary of the total inorganic arsenic, As(III)
and As(V) concentrations (µg L−1 ) determined in 73 wa-
ter samples from deep artesian wells collected at the dairy
farms located at the seven counties of Comarca Lagunera
Countiesa N Arithmetic Standard Maximum
mean deviation
Arsenic (III)
1 12 0.67 0.25 1
2 15 8.33 5.12 19
3 6 5.83 5.04 12
4 26 1.08 1.18 5
5 3 6.67 – 9
6 3 0.50 – <1
7 8 0.68 1.13 2
Arsenic (V)
1 12 42.33 14.57 73
2 15 349 156 581
3 6 406 315 730
4 26 57.54 74.45 262
5 3 415 – 484
6 3 7.00 – 7
7 8 29.00 3.12 35
Inorganic total arsenic
1 12 42.67 52.19 74
2 15 357 160 590
3 6 411 319 740
4 26 58.23 75.58 265
5 3 422 – 490
6 3 7.00 – 7
7 8 29.65 3.10 35
a The county numbers are indicated in Figure 1.
Total arsenic soil levels ranged from 11 to 30 µg g−1 (Figure 2). The main type
of soil in the sampled farms was sandy clay loam (Table III). The extractable ar-
senic was not higher than 15%, with the highest values found in farms at Tlahualilo
and Francisco I. Madero counties (Figures 3 and 4). The Mann-Whitney test showed
non-significant differences in total As between soils 0–30 and 30–60 cm depth
horizons (Z=0.50, p=0.05).
8. 140 I. ROSAS ET AL.
TABLE II
Chemical parameters in groundwater samples from farms located in different
counties at the Comarca Lagunera
Countiesa SO2−
4 Cl− PO3− -P
4 Na+ K+ Ca2+ Mg2+ pH
mg L−1
1 213 24.4 0.02 72.5 52.4 70.9 7.2 7.9
2 335 29.5 0.04 410 16.3 120 15.1 8.0
3 245 21.3 0.04 198 7.8 29.0 3.4 8.2
4 344 68.0 0.02 95.0 39.3 108 20.4 7.9
5 278 87.2 0.01 66.0 22.6 39.5 5.3 8.2
6 182 19.3 0.01 34.0 48.5 57.3 5.9 7.9
7 428 70.1 0.01 185 24.8 116 36.4 7.8
a The county numbers are indicated in Figure 1.
Figure 3. Arsenic concentrations in washed alfalfa and extractable arsenic in soils from dairy farms
located at different counties.
9. ARSENIC CONCENTRATIONS IN WATER, SOIL, MILK AND FORAGE 141
Figure 4. Proportion of extractable arsenic in soil from alfalfa fields in farms located at different
counties.
TABLE III
Physical and chemical characteristics of soil samples from alfalfa fields
at the Comarca Lagunera
Countiesa Soil texture O.M. Sand Silt Clay pH
%
1 Sandy clay loam 1.4 26 40 34 8.4
2 Sandy clay loam 0.6 33 40 27 8.3
3 Sandy clay loam 0.5 33 36 31 8.3
4 Sandy clay loam 0.7 35 36 29 8.5
5 Sandy clay loam 0.9 27 41 32 8.3
6 Clay loam 1.2 27 34 39 8.3
7 Sandy clay loam 1.05 36 36 28 8.6
a The county numbers are indicated in Figure 1.
10. 142 I. ROSAS ET AL.
TABLE IV
Values of total arsenic in milk (ng g−1 ) collected from farms located at
different counties
Countiesa N Arithmetic Standard Minimum Maximum
mean deviation
1 6 1.63 1.64 <0.90 3.90
2 6 1.04 0.50 <0.90 1.50
3 6 8.59 11.75 <0.90 27.40
4 18 2.42 3.49 <0.90 14.80
5 3 5.18 – 2.50 6.70
6 3 2.60 – <0.90 5.05
7 8 1.37 1.24 0.90 3.87
a The county numbers are indicated in Figure 1.
A higher percent of total arsenic was observed in alfalfa at root level than at
the aerial structures (Figure 3), but a good correlation (r=0.70, p=0.01) exist be-
tween the arsenic in roots and extractable arsenic in soil 0–30 and 30–60 cm depth
horizons.
The median of the washed and unwashed alfalfa corresponded to 0.9 and 1.6 µg
g , respectively and those corresponding to corn’s silage were 0.5 and 1 µg g−1 ,
−1
respectively (Figure 5). About 50% of the arsenic was removed by washing. Sig-
nificant differences (Z=3.3, p=0.05) were observed between washed and unwashed
plants.
Total arsenic concentrations from cow’s milk ranged from 0.9 to 27.4 ng g−1
with the highest values in farms at Francisco I. Madero and Matamoros counties
(Table IV).
Significant correlations (p=0.01) between arsenic (III), (V) and total inorganic
concentrations in water with extractable As in soil (0–30 cm depth horizon), with
As in alfalfa (leaves and roots) and with As in milk were observed (Table V).
The biotransfer factor calculated for arsenic in milk was 10−4 , except for Tlahualilo
county, with 10−5 . It was calculated based on the cow’s average daily intake of
arsenic that ranged from 4 to 38.8 mg day−1 (Table VI).
4. Discussion
High concentrations of arsenic in water, air and soil have been associated with
industrial wastes or natural processes (Borgoño et al., 1977; Whanger et al., 1977;
Sims and Kline, 1991; Retana et al., 1993; Santander et al., 1994; Nakadaira et al.,
1995; Hwang et al., 1997). Due to the toxicity of As to plants, animals and human,
11. ARSENIC CONCENTRATIONS IN WATER, SOIL, MILK AND FORAGE 143
Figure 5. Box plot of arsenic concentrations in washed (1) and unwashed (2) of alfalfa and forage
samples. The triangle symbol marks the minimum and maximum values. The symbols in bottom and
top of the vertical line mark the 5th and 95th percentiles, respectively. The circle symbol, median
line, the bottom and the top in the box mark: the arithmetic mean, 50th, 25th and 75th percentiles,
respectively.
it is desirable to understand its behavior in the environment (Vahter and Morin,
1980; Nissen and Benson 1982; USEPA, 1984; Wu et al., 1989; Sheppard, 1992).
In the Comarca Lagunera, Mexico, high levels of arsenic have been detected in
ground water, used not only as drinking water for humans and dairy cattle, but also
for agricultural irrigation. Forty percent of the water samples from dairy farms had
total arsenic contents above the USEPA (1980) and DOF (1996) National Drinking
Water Standards (50 µg L−1 )], but only 5 samples were below the WHO (1993)
standard of 10 µg L−1 . Arsenic contents below the drinking water standard were
found only in one farm of Torreón. The arsenic concentrations measured in the
studied area were lower than those reported at other zones of Mexico, like Zimapan,
a Village in Hidalgo (up to 1.09 mg L−1 ) (Armienta et al., 1997a). On the other
hand, As levels at Francisco I. Madero, Tlahualilo and San Pedro farms are within
those values reported in Antofagasta, Chile, where skin cancers were described
12. 144 I. ROSAS ET AL.
TABLE V
Linear correlation coefficients between arsenic concentration in water and
those from soil, alfalfa crops and milk
Groundwater
As (III) As (V) Inorganic total As
Soil
total As, 0–30 cm –0.289 –0.056 –0.046
total As, 30–60 cm –0.188 –0.145 –0.152
extractable As, 0–30 cm 0.494a –0.553a 0.539a
extractable As, 30–60 cm 0.137 0.214 0.229
Alfalfa:
stem 0.475a 0.509a 0.504a
root 0.546a 0.559a 0.571a
Milk 0.525a 0.510a 0.507a
a Significant at the 1% level (N=43).
TABLE VI
Estimated biotransfer factor to milk collected from dairy farms at the
Comarca Lagunera
Countiesa Forage Water Intake Milk BTF
mg kg−1 mg L−1 mg day−1 µg L−1
1 0.60 0.042 8.7 1.7 1.9* 10−4
2 1.34 0.36 36.6 1.2 3.2* 10−5
3 1.21 0.41 38.8 8.9 2.2* 10−4
4 1.20 0.06 15.6 2.6 1.6* 10−4
5 0.88 0.42 36.1 5.3 1.4* 10−4
6 0.40 0.007 4.0 2.7 6.7* 10−4
7 1.03 0.30 12.1 1.4 1.1* 10−4
a The county numbers are indicated in Figure 1.
among the residents, who had been drinking water containing from 0.05 to 0.96
mg L−1 of As; and in southwestern Taiwan, where the As level ranged from 0.01
to 1.82 mg L−1 , in artesian water (Morton and Dunnette, 1994; Tseng, 1977). It
has been established a consensus of a threshold value of 100 µg L−1 (tropical
consumption) for arsenic disease (Stöhrer, 1991).
13. ARSENIC CONCENTRATIONS IN WATER, SOIL, MILK AND FORAGE 145
Arsenic-concentration in the studied area, showed an increase of the As to-
wards the north of the Comarca Lagunera, with lower levels at its center. The
observed variations may be due to differences in the geology, the hydrogeology
and the abstraction regime of this area. The arsenic enrichment has been ascribed
to magmatic processes giving rise to a hydrothermal system with high contents
of lithium, boron, arsenic and fluoride (González-Hita et al., 1991). Differences
in arsenic concentrations have been found also at Zimapán, related to the various
arsenic sources (natural and anthropogenic) and to the hydrogeology of the valley
(Armienta et al., 1997a).
According to the results of pH and of major ions concentrations in the water
samples, the Souliné classification was used (Custodio, 1983). Most of the water
samples pertain to the sulfate-sodium type and some of them to the bicarbonate-
sodium type. The pH results, of 7.5 to 8.4, also indicate that precipitation re-
actions including As are not likely to occur. It seems that this element is not
totally eliminated from water (Cherry et al., 1979). However, it is necessary to
complete the data with more analyses of major and minor species to fully support
this conclusion.
None of the samples exceeded the allowable limit (1.0 mg L−1 ) of arsenic for
water used in irrigation (USEPA, 1973).
Ground water is also consumed by dairy cattle at the Comarca Lagunera, which
is one of the most important dairy cows raising zone in Mexico. The arsenic con-
centrations in the water could affect human health through milk intake, since the
allowable limit for water used to feed cattle is 0.05 mg L−1 (USEPA, 1973).
Total arsenic concentrations in soils from alfalfa fields at the dairy farms varied
from 11 to 30 µg g−1 . These values are within the average normal concentrations
for arsenic in agriculture soils in the USA (from 1 to 40 µg g−1 ) (Walsh et al.,
1977), and lower than 50 µg g−1 , considered as guideline for soil pollution (Min-
istry of Environment, 1990). Nevertheless, the As average concentrations are above
6 µg g−1 reported for non-polluted soils (USEPA, 1985), and exceeded the 10 µg
g−1 suggested as background (O’Neil, 1995; Sheppard, 1992).
Arsenic in soils is normally bounded to clay containing amorphous aluminum
and iron oxihydroxides. The mobility of arsenic depends on the kind of soil, pH,
and on the iron, aluminum and phosphate contents (Pierce and Moore, 1982; Mok
and Wai, 1994). It has been observed that a drop in pH and an increase in fulvic
acid increases arsenic leaching (Bowell, 1994). At the Comarca Lagunera the soil is
mostly clay, with a low content of organic matter and a alkaline pH (> 8.0). These
characteristics explain the low percentage of extractable arsenic with respect to
total arsenic. It seems that arsenic is mostly retained on the silt and clay fractions
of the soils which constitute more than 50% of their granulometry. Nevertheless,
some differences were observed among the sampled farms, the highest proportions
of extractable arsenic were found at Tlahualilo, F. I. Madero and San Pedro farms
with soil samples containing more than 30% of sand.
14. 146 I. ROSAS ET AL.
Arsenic pollution in soils may have effects on vegetation and easily affects the
animals that graze on grass. The observed concentrations of total arsenic in soils,
although above the EPA values, are within those reported for agricultural soils in
the United States (Walsh and Keeney, 1975).
The plant damage has been used as indicator to determine the critical concen-
tration of soluble As in soils. Above 1 µg g−1 cause damage to crops (Huang,
1994). The extractable arsenic at La Comarca Lagunera does not seem to represent
an important risk for the vegetation. However, some plants can tolerate higher
concentrations of arsenic. For plants to reach levels of 1 mg kg−1 of As on fresh
weight basis, soils levels must exceed 200 to 500 mg kg−1 (Aten et al., 1980). On
the other hand, some crops can accumulate high levels of As even at much lower
levels of arsenic in soil. For instance, alfalfa and grass accumulate up to 14 mg
kg−1 of As when growing in soils containing 60 mg kg−1 of As (Bhumbla and
Keefer, 1994).
At the Comarca Lagunera, alfalfa and corn’s silage As concentrations were
similar to the arsenic content in grass (as much as 3 mg kg−1 ) growing in soils
containing up to 20 mg kg−1 of As (O’Neill, 1995). The As distribution in the
plants was in general similar to that observed in other studies, with higher As levels
in roots than in stem and leaves.
Variations in arsenic concentrations in plants were also observed for the various
farms, related to As contents in soils. Higher As values were measured in plants
growing in soils with higher extractable arsenic. The samples from counties, 2, 3,
4 and 5, corresponding to soils with higher peoportion of sand, had the highest
As levels. In general, lower levels have been found in plants growing on clays and
silts, with higher clay, minerals and Fe/Al oxide content, than in plants growing in
lighter soils, e.g. sands or sandy-loam soils (O’Neill, 1995). This behavior reflects
the fact that the composition of vegetation depends on the availability of an element
in the vicinity of the root system and the ability of the plant to absorb, transport,
and accumulate the element (Lintern et al., 1997). The adsorption of metals from
the liquid phase to the solid phase controls the concentrations of metal ions and
complexes in the soil solution and thus exerts a major influence on their uptake
by plant roots (Alloway, 1995). The high proportion of sand in counties 2, 3, 4
and 5, implies lower adsorption of arsenic and higher availability for the plants. A
soil-plant transfer coefficient (metal concentration in the plant divided by the total
metal content of the superficial soil) from 0.02 to 0.09 was calculated, this values
agree with the reported coefficients at other places (Alloway et al., 1988; Alloway,
1995).
Alfalfa and corn’s silage were analyzed because they are important components
of the diet of dairy cattle. The arsenic present in soil was absorbed by alfalfa crop
and 37% of the samples were higher than 2.6 µg g−1 , considered as permissible
limit for edible crops by US Public Health Service (Jones and Hatch, 1945). It
has been reported an important accumulation of arsenic at root level (Sheppard,
et al., 1985; Sheppard, 1992; Retana et al., 1993). The average root/stem-leaves
15. ARSENIC CONCENTRATIONS IN WATER, SOIL, MILK AND FORAGE 147
ratio was of 1.7. However, almost the whole plant (with part of the roots) is used
as forage for dairy cattle including the absorbed arsenic associated to soil particles,
this represented about 30% of the total arsenic in plants.
The fact that the heavy metals have been capable of translocating into bovine
milk has been previously reported (Sharma et al., 1982; Stevens, 1991). The Co-
marca Lagunera is one of the most important dairy producers in Mexico. Therefore,
it is important to determine the contribution of arsenic from agricultural food chain
to bovine milk. Ten percent of the milk samples had a concentration of As > 10 ng
g−1 , suggested as permitted arsenic level (International Dairy Federation, 1986).
The biotransfer factor has been calculated based in metal levels in food, but in
this study the arsenic present in drinking water was included, and factors up to 6.7
× 10−4 , were higher than those reported in an experimental study (1.1 × 10−5 )
(Stevens, 1991).
It is important to consider that more than 30% of the arsenic measured in plants
was adsorbed by leaves and probably only a very low proportion of this is accessi-
ble to cattle by ingestion (Hwang et al., 1997). Also, extractable data suggest that
the inorganic arsenic absorbed by plants may be converted to organic arsenic com-
pounds. Thus, methylation of arsenic in vegetables should substantially reduce the
estimated risk associated with the food ingested dose (Nissen and Benson, 1982;
Pyles and Woolson, 1982). In contrast, the solubility of arsenic in water, mainly as
As (V), determine that this could be the most important source of arsenic exposure
in the studied area.
Acknowledgments
We acknowledge to Hugo Padilla G. and Pilar Fernández for the review of the
manuscript and his valuable comments. Also to CONACYT for the partial financial
support.
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