This study investigated the abundance and age of dissolved black carbon (DBC) in the ocean. The key findings are:
1) DBC concentrations in the Atlantic, Pacific, and Arctic oceans ranged from 1.4 to 2.6 μM in surface waters and was 1.2 μM in the deep Atlantic.
2) The average age of surface DBC was 4,800 years while deep Atlantic DBC was much older at 23,000 years.
3) The varying structures and ages of DBC indicate there are at least two distinct pools - a younger pool cycling over centuries and an ancient pool cycling over 100,000 years.
I created this poster for the 2017 Arctic Change Conference.
The poster is a preliminary research that focuses on the Geochemistry of parts of the Canadian Hudson Bay.
Keywords:
Hydrocarbons
Radioisotopes
Redox Elements
Total Organic Carbon
Principal Components Analysis
Sediments
Hydrogeochemistry and Microbiology of Wadi Al Bih Limestone Aquifer in Northe...QUESTJOURNAL
ABSTRACT: This study investigated the hydrogeochemical characteristics and microbiological pollution of groundwater in Wadi Al Bih limestone aquifer, Ras Al Khaimah area, northern United Arab Emirates (UAE). Results indicate that the decrease of groundwater exploitation in Wadi Al Bih basin from 58 million cubic meter (MCM) during the period 1991-1995 to 22 MCM during the period 2011-2015, has increased groundwater storage, raised hydraulic heads by 1 m in Al Burayrat area and 16 m near Wadi Al Bih main dam, and decreased the average groundwater salinity by 30% in Wadi Al Bih well field and 45% in Al Burayrat well field. Results of chemical analyses showed noticeable fluctuations in groundwater temperature, EC, and TDS contents, rather than concentrations of all ions. The November 2014 and June 2015 isosalinity contour maps indicate that the groundwater salinity increases from east to west, in the direction of groundwater flow. The groundwater in the eastern part of Wadi Al Bih is good for domestic purposes and irrigation. However, the water hardness is high because the aquifer is predominantly composed of limestone. Wadi Al Bih limestone aquifer is highly sensitive to urban and agricultural activities, and several well were recorded to have Coliform bacteria in Wadi Al Bih and Al Burayrat areas
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.
This document provides an overview of ocean chemistry concepts including the unique properties of water, the composition of seawater, and factors that influence ocean salinity. It discusses how water is able to dissolve many substances due to its polar molecular structure and hydrogen bonding. Seawater contains approximately 3.5% dissolved salts by mass, primarily sodium and chloride. Processes such as evaporation and precipitation impact salinity levels regionally. Buffering systems help maintain the ocean's near-neutral pH.
The document discusses acids, bases, and pH. It explains that acids donate H+ ions while bases accept H+ ions. Common acids include HCl and carbonic acid, while NaOH is a strong base. Neutralization reactions between acids and bases produce water and salts. Buffers resist changes in pH. The pH scale ranges from 0-14 with acidic solutions having a pH below 7 and basic solutions above 7. The carbonate buffering system and carbon dioxide system in the ocean help regulate ocean pH. Increasing carbon dioxide absorption is lowering ocean pH and threatening marine organisms with calcium carbonate shells or skeletons.
The water chemistry of two Appalachian streams, Little Tumbling Creek (LTC) and North Fork Stony Creek (NFSC), was studied to develop acid mitigation plans. Both streams have low pH and buffering capacity due to geology with few minerals. LTC was treated with limestone, increasing pH and buffering slightly, but not to targets. Additional limestone of varying sizes is recommended. NFSC needs similar treatment, and 100 tons of limestone is calculated to offset acidity based on LTC results. The goal is to improve water chemistry and reestablish aquatic life in both streams.
Shaheen_PNAS2014_ALH84001-oldest rock from MarsRobina Shaheen
This study analyzed carbonate minerals in the Martian meteorite ALH 84001 to understand the evolution of Mars' ancient atmosphere. The key findings were:
1) Carbonate minerals in ALH 84001 showed two distinct isotope compositions, indicating at least two separate formation events.
2) A Ca-rich carbonate phase had higher 18O and 13C isotopes than a Fe-rich phase, suggesting they formed under different atmospheric conditions.
3) The Ca-rich phase formed after an initial aqueous event 3.9 billion years ago and captured the isotope signatures of Mars' atmosphere, hydrosphere, and surface interactions at that time.
4) The 13C depletion in the Ca-
The document discusses the carbonate system and chemical weathering. It describes the carbonate equilibrium reactions and species like carbonic acid, bicarbonate, and carbonate that are involved. Chemical weathering plays an important role in regulating atmospheric carbon dioxide and climate by slowly breaking down continental rocks and sequestering carbon over millions of years. Factors like temperature, precipitation, and vegetation influence chemical weathering rates and provide negative feedback that moderates global temperatures.
I created this poster for the 2017 Arctic Change Conference.
The poster is a preliminary research that focuses on the Geochemistry of parts of the Canadian Hudson Bay.
Keywords:
Hydrocarbons
Radioisotopes
Redox Elements
Total Organic Carbon
Principal Components Analysis
Sediments
Hydrogeochemistry and Microbiology of Wadi Al Bih Limestone Aquifer in Northe...QUESTJOURNAL
ABSTRACT: This study investigated the hydrogeochemical characteristics and microbiological pollution of groundwater in Wadi Al Bih limestone aquifer, Ras Al Khaimah area, northern United Arab Emirates (UAE). Results indicate that the decrease of groundwater exploitation in Wadi Al Bih basin from 58 million cubic meter (MCM) during the period 1991-1995 to 22 MCM during the period 2011-2015, has increased groundwater storage, raised hydraulic heads by 1 m in Al Burayrat area and 16 m near Wadi Al Bih main dam, and decreased the average groundwater salinity by 30% in Wadi Al Bih well field and 45% in Al Burayrat well field. Results of chemical analyses showed noticeable fluctuations in groundwater temperature, EC, and TDS contents, rather than concentrations of all ions. The November 2014 and June 2015 isosalinity contour maps indicate that the groundwater salinity increases from east to west, in the direction of groundwater flow. The groundwater in the eastern part of Wadi Al Bih is good for domestic purposes and irrigation. However, the water hardness is high because the aquifer is predominantly composed of limestone. Wadi Al Bih limestone aquifer is highly sensitive to urban and agricultural activities, and several well were recorded to have Coliform bacteria in Wadi Al Bih and Al Burayrat areas
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.
This document provides an overview of ocean chemistry concepts including the unique properties of water, the composition of seawater, and factors that influence ocean salinity. It discusses how water is able to dissolve many substances due to its polar molecular structure and hydrogen bonding. Seawater contains approximately 3.5% dissolved salts by mass, primarily sodium and chloride. Processes such as evaporation and precipitation impact salinity levels regionally. Buffering systems help maintain the ocean's near-neutral pH.
The document discusses acids, bases, and pH. It explains that acids donate H+ ions while bases accept H+ ions. Common acids include HCl and carbonic acid, while NaOH is a strong base. Neutralization reactions between acids and bases produce water and salts. Buffers resist changes in pH. The pH scale ranges from 0-14 with acidic solutions having a pH below 7 and basic solutions above 7. The carbonate buffering system and carbon dioxide system in the ocean help regulate ocean pH. Increasing carbon dioxide absorption is lowering ocean pH and threatening marine organisms with calcium carbonate shells or skeletons.
The water chemistry of two Appalachian streams, Little Tumbling Creek (LTC) and North Fork Stony Creek (NFSC), was studied to develop acid mitigation plans. Both streams have low pH and buffering capacity due to geology with few minerals. LTC was treated with limestone, increasing pH and buffering slightly, but not to targets. Additional limestone of varying sizes is recommended. NFSC needs similar treatment, and 100 tons of limestone is calculated to offset acidity based on LTC results. The goal is to improve water chemistry and reestablish aquatic life in both streams.
Shaheen_PNAS2014_ALH84001-oldest rock from MarsRobina Shaheen
This study analyzed carbonate minerals in the Martian meteorite ALH 84001 to understand the evolution of Mars' ancient atmosphere. The key findings were:
1) Carbonate minerals in ALH 84001 showed two distinct isotope compositions, indicating at least two separate formation events.
2) A Ca-rich carbonate phase had higher 18O and 13C isotopes than a Fe-rich phase, suggesting they formed under different atmospheric conditions.
3) The Ca-rich phase formed after an initial aqueous event 3.9 billion years ago and captured the isotope signatures of Mars' atmosphere, hydrosphere, and surface interactions at that time.
4) The 13C depletion in the Ca-
The document discusses the carbonate system and chemical weathering. It describes the carbonate equilibrium reactions and species like carbonic acid, bicarbonate, and carbonate that are involved. Chemical weathering plays an important role in regulating atmospheric carbon dioxide and climate by slowly breaking down continental rocks and sequestering carbon over millions of years. Factors like temperature, precipitation, and vegetation influence chemical weathering rates and provide negative feedback that moderates global temperatures.
This is an introduction to Maggie Ziriax\'s project on the stable isotope analysis of the teeth from Necropolis 6. Hopefully we can find out more about this population\'s diet and geographical origins from this analysis. Good luck Maggie!
The document summarizes a research project aiming to reconstruct late Holocene environmental changes in the Shuaiba Lagoon area of Saudi Arabia using lipid biomarkers from sediment cores. Sediment samples spanning 3600 years will be analyzed to determine past sea surface temperatures through lipid proxies, including alkenones and diols. The samples will undergo total lipid extraction and fractionation before being analyzed by gas chromatography–mass spectrometry and gas chromatography–flame ionization detection to measure lipid concentrations and calibrate to temperatures. This will provide insights into climate variability in the region over the last millennium.
The SABRE project aimed to demonstrate the effectiveness of in situ enhanced anaerobic bioremediation for treating chlorinated solvent DNAPL source areas. It involved laboratory experiments, field tests at a contaminated site in the UK, and development of investigation and modeling tools. The laboratory experiments showed that reductive dechlorination of TCE to ethene was possible using an emulsified soy oil electron donor and nutrient addition. Field tests involved constructing a test cell through a DNAPL source area and injecting the emulsified soy oil, with monitoring showing enhanced DNAPL dissolution and degradation. The project advanced understanding of bioremediating DNAPL sources and demonstrated the technique for the first time in the UK.
This document summarizes the potential for using accelerated weathering of limestone (AWL) as an alternative method for carbon dioxide mitigation from point sources like power plants. AWL involves reacting CO2 gas with limestone and water to form stable calcium bicarbonate solutions. This process is spontaneous and exothermic. Storing carbon in the ocean as calcium bicarbonate raises alkalinity and helps counteract ocean acidification. Initial modeling suggests AWL could sequester CO2 for under $3 per tonne, much cheaper than conventional carbon capture and storage. Globally, there is enough limestone and seawater to potentially store over 100,000 gigatons of carbon via this process
Stable oxygen and carbon isotopes can be used as proxies for paleoclimate reconstruction. Oxygen isotopes in carbonate shells vary based on temperature and ice volume, providing information about glacial/interglacial cycles. Carbon isotopes reflect the global carbon cycle and can indicate changes in productivity, circulation, and terrestrial carbon storage over time.
The document discusses using ammonium nitrate injections to enhance monitored natural attenuation (MNA) at a site with dissolved petroleum contamination. Baseline testing found the aquifer had a microbial population but limited nutrients and terminal electron acceptors. Approximately 116 pounds of ammonium nitrate fertilizer was injected, providing a source of nitrate to drive biodegradation. Monitoring after injection found increased biological activity and degradation rates, showing nitrate addition can accelerate MNA by stimulating microbial growth where nutrients were previously limited.
This document summarizes a study examining seasonal patterns of nutrient retention in a restored tidal freshwater stream. The study measured water and nutrient fluxes, estimated ecosystem metabolism through dissolved oxygen patterns, and identified factors controlling nutrient retention. Key results included macro-tidal water exchange driven by river depth, conservative behavior of chloride but retention of nitrogen and phosphorus, and higher retention during periods of lower metabolism in winter months.
Ghoorah et al_2014_Selection of acid for weak acid processing of wollastonite...Reydick D Balucan
This document evaluates three weak organic acids (formic, acetic, and DL-lactic acid) for extracting calcium from wollastonite at temperatures between 22°C and 80°C. Experiments found that formic acid achieved the highest calcium extraction rate of 26(±7) × 10−5 mol m−2 s−1 at 80°C, followed by acetic acid and DL-lactic acid. Activation energies indicated the initial dissolution in formic acid was diffusion controlled, while kinetic limitations controlled dissolution in acetic and DL-lactic acids. Formic acid showed the best performance for calcium extraction and potential for mineral carbonation.
Boron isotope Ratio as a paleo pH proxyMOHD TARIQUE
This document discusses using boron isotopic ratios to reconstruct past ocean pH and atmospheric CO2 levels. It explains that boron isotopes fractionate between boric acid and borate ions in seawater in a pH-dependent manner, allowing paleo-pH to be determined. The study proposes measuring boron isotopes in carbonate samples from the Southern Ocean and tropical Indian Ocean to reconstruct CO2 variations over geological and modern timescales and understand how ocean acidification may impact marine ecosystems in the future.
- pH is a measure of how acidic or basic a solution is, with values from 0 to 14. Solutions with a pH less than 7 are acidic and greater than 7 are basic.
- The pH scale is determined by international agreement and is based on standard buffer solutions. pH can be measured using a glass electrode and meter or indicators.
- pH is important in many applications including biology, medicine, agriculture and more. It is calculated as the negative logarithm of the hydronium ion concentration.
- For strong acids and bases, pH can be calculated directly from concentration but weak acids and bases require more complex calculations using acid dissociation constants and mass balances.
This study aims to quantify the amount of organic carbon stored in clastic floodplain deposits compared to organic-rich wetland deposits in the Mississippi Delta. Total organic carbon, sediment bulk density, and chronology/accretion rates will be measured from cores taken in Bayou Lafourche, Louisiana. Total organic carbon will be quantified using both loss on ignition and elemental analysis. Sediment texture will be correlated with carbon content. Bulk density and radiocarbon/optically stimulated luminescence dating will provide chronology to calculate annual accumulation rates of organic carbon over time. Comparing storage in floodplains versus wetlands will improve understanding of carbon sequestration in these environments.
The document reports on an experimental study to determine the pKa (acid dissociation constant) of perfluorooctanoic acid (PFOA) using potentiometric titration in a water-methanol mixed solvent system. The study found:
1) The pKa of monomeric PFOA was determined to be 3.8 ± 0.1. This value is important for understanding the environmental fate of PFOA as both its ionized and non-ionized forms have different physicochemical properties.
2) The pKa was suppressed to around 2.3 at higher PFOA concentrations due to aggregation of its conjugate base. Many previous studies measured partitioning coefficients at concentrations above environmental levels,
Carbonate removal from coastal sediments for the determination of organic c a...Mahbubul Hassan
The document compares two methods for removing inorganic carbon from samples to isolate organic carbon for analysis: the aqueous method using hydrochloric acid (HClaq) and the vaporous method using hydrochloric acid vapor (HClvap). It evaluates the methods based on their ability to have low blank levels, efficiently remove dolomite, yield accurate measurements of organic carbon percentage and isotopic signatures (δ13C and Δ14C). The vaporous method met all criteria if samples were not overexposed to acid. The aqueous method gave similar results but was less reliable and consistently underestimated organic carbon percentage. Optimal acid exposure times need to be determined for each sample type to obtain the most accurate isotopic measurements.
This document provides an overview of stable sulfur isotopes. It begins with definitions of isotopes and discusses the four stable isotopes of sulfur - 32S, 33S, 34S, and 36S. It then explains how sulfur isotope ratios are measured using mass spectrometry and discusses some typical isotope variations seen in nature. Applications of sulfur isotopes include tracing sulfur sources in hydrology and studying mantle processes. In conclusion, the document reinforces that sulfur has four stable isotopes and occurs in a variety of geological materials and environments.
Efficiency of Carbonate Precipitation and Removal of Copper and Nickel Ions f...AnuragSingh1049
The effect of pH and initial concentration on the removal of Cu(II) and Ni(II) ions from their monocomponent and two-component aqueous solutions using Na2CO3 as a chemical precipitation agent was investigated in this paper. Monocomponent aqueous solutions of Cu(II) and Ni(II) ions with their initial concentrations of 50 and 500 mg/L and two-component aqueous solution with initial concentration of 500 mg/L were prepared. The precipitation was carried out by batch method at room temperature by stirring the solution at 300 rpm for 5 minutes, resulting in the formation of precipitates. The resulting precipitate was separated by filtration from the solution. The experiment proved that Na2CO3 is a good agent for removing Cu(II) and Ni(II) ions from their monocomponent water solutions of 50 and 500 mg/L concentration and two-component water solution with initial concentration of each metal 500 mg/L. The percentage of Cu(II) removal was higher at lower pH values compared to Ni(II) removal.
Visible light assisted hydrogen generation from complete decomposition of hyd...Pawan Kumar
Hydrogen is considered to be an ideal energy carrier, which produces only water when combined with
oxygen and thus has no detrimental effect on the environment. While the catalytic decomposition of
hydrous hydrazine for the production of hydrogen is well explored, little is known about its photocatalytic
decomposition. The present paper describes a highly efficient photochemical methodology for the production
of hydrogen through the decomposition of aqueous hydrazine using titanium dioxide nanoparticles
modified with a Rh(I) coordinated catechol phosphane ligand (TiO2–Rh) as a photocatalyst under visible
light irradiation. After 12 h of visible light irradiation, the hydrogen yield was 413 μmol g−1 cat with a hydrogen
evolution rate of 34.4 μmol g−1 cat h−1. Unmodified TiO2 nanoparticles offered a hydrogen yield of
83 μmol g−1 cat and a hydrogen evolution rate of only 6.9 μmol g−1 cat h−1. The developed photocatalyst
was robust under the experimental conditions and could be efficiently reused for five subsequent runs
without any significant change in its activity. The higher stability of the photocatalyst is attributed to the
covalent attachment of the Rh complex, whereas the higher activity is believed to be due to the synergistic
mechanism that resulted in better electron transfer from the Rh complex to the conduction band of TiO2.
1) Acid mine drainage is a major water pollution problem in Pennsylvania due to the state's long history of coal mining. When pyrite in coal mines is exposed to air and water, it produces sulfuric acid and dissolved metals that severely degrade water quality and aquatic habitats.
2) Chemical treatment using alkaline substances like limestone is currently the most common method to neutralize acidity and precipitate metals out of the water. However, it is expensive to operate and maintain. Passive treatment methods like constructed wetlands are becoming more widely used because they have lower long-term costs.
3) Wetlands can successfully remediate acid mine drainage through natural processes that raise the pH and remove metals. Pennsylvania is
UCSC Master's Presentation by Wilson SauthoffWilson Sauthoff
The document discusses using nitrogen isotopes of amino acids in marine sediments as a tool to assess changes in organic matter quality and supplied nitrate δ15N over time. It presents results from a study of nitrogen isotope ratios in amino acids extracted from sediment cores collected across a range of depositional environments in the Eastern Tropical Pacific. The study finds that amino acid δ15N patterns are generally well preserved in sediments with lower oxygen exposure times, but become increasingly altered from the original sinking particulate organic matter in sediments with higher oxygen exposure times and more degradation. It also finds that the offset between δ15N of bulk sediments and total hydrolysable amino acids decreases with greater degradation. This has implications for using amino acid δ15N values to
Ocean Acidification: Cause, Impact and mitigationIIT Kanpur
Ocean Acidification and the battle for Carbonate.
In this presentation the points covered are detailed briefing of ocean acidification, its causes, its impact on marine ecosystems and measures to mitigate this.
This document summarizes a study on carbon regeneration in the water column of the Cariaco Basin, Venezuela. The key findings are:
1) Carbon dioxide levels were lowest at the surface (1962 μmol/kg) and increased below the oxic-anoxic redox interface to 2451 μmol/kg.
2) Vertical carbon regeneration was dominated by organic carbon from photosynthetic organisms (82%), with the remaining 18% from biogenic calcite dissolution.
3) The highest organic carbon regeneration occurred in the surface layer consistent with primary productivity, and a secondary maximum (70-80%) was detected at the oxic-anoxic interface driven by chemotrophic microbe respiration
This is an introduction to Maggie Ziriax\'s project on the stable isotope analysis of the teeth from Necropolis 6. Hopefully we can find out more about this population\'s diet and geographical origins from this analysis. Good luck Maggie!
The document summarizes a research project aiming to reconstruct late Holocene environmental changes in the Shuaiba Lagoon area of Saudi Arabia using lipid biomarkers from sediment cores. Sediment samples spanning 3600 years will be analyzed to determine past sea surface temperatures through lipid proxies, including alkenones and diols. The samples will undergo total lipid extraction and fractionation before being analyzed by gas chromatography–mass spectrometry and gas chromatography–flame ionization detection to measure lipid concentrations and calibrate to temperatures. This will provide insights into climate variability in the region over the last millennium.
The SABRE project aimed to demonstrate the effectiveness of in situ enhanced anaerobic bioremediation for treating chlorinated solvent DNAPL source areas. It involved laboratory experiments, field tests at a contaminated site in the UK, and development of investigation and modeling tools. The laboratory experiments showed that reductive dechlorination of TCE to ethene was possible using an emulsified soy oil electron donor and nutrient addition. Field tests involved constructing a test cell through a DNAPL source area and injecting the emulsified soy oil, with monitoring showing enhanced DNAPL dissolution and degradation. The project advanced understanding of bioremediating DNAPL sources and demonstrated the technique for the first time in the UK.
This document summarizes the potential for using accelerated weathering of limestone (AWL) as an alternative method for carbon dioxide mitigation from point sources like power plants. AWL involves reacting CO2 gas with limestone and water to form stable calcium bicarbonate solutions. This process is spontaneous and exothermic. Storing carbon in the ocean as calcium bicarbonate raises alkalinity and helps counteract ocean acidification. Initial modeling suggests AWL could sequester CO2 for under $3 per tonne, much cheaper than conventional carbon capture and storage. Globally, there is enough limestone and seawater to potentially store over 100,000 gigatons of carbon via this process
Stable oxygen and carbon isotopes can be used as proxies for paleoclimate reconstruction. Oxygen isotopes in carbonate shells vary based on temperature and ice volume, providing information about glacial/interglacial cycles. Carbon isotopes reflect the global carbon cycle and can indicate changes in productivity, circulation, and terrestrial carbon storage over time.
The document discusses using ammonium nitrate injections to enhance monitored natural attenuation (MNA) at a site with dissolved petroleum contamination. Baseline testing found the aquifer had a microbial population but limited nutrients and terminal electron acceptors. Approximately 116 pounds of ammonium nitrate fertilizer was injected, providing a source of nitrate to drive biodegradation. Monitoring after injection found increased biological activity and degradation rates, showing nitrate addition can accelerate MNA by stimulating microbial growth where nutrients were previously limited.
This document summarizes a study examining seasonal patterns of nutrient retention in a restored tidal freshwater stream. The study measured water and nutrient fluxes, estimated ecosystem metabolism through dissolved oxygen patterns, and identified factors controlling nutrient retention. Key results included macro-tidal water exchange driven by river depth, conservative behavior of chloride but retention of nitrogen and phosphorus, and higher retention during periods of lower metabolism in winter months.
Ghoorah et al_2014_Selection of acid for weak acid processing of wollastonite...Reydick D Balucan
This document evaluates three weak organic acids (formic, acetic, and DL-lactic acid) for extracting calcium from wollastonite at temperatures between 22°C and 80°C. Experiments found that formic acid achieved the highest calcium extraction rate of 26(±7) × 10−5 mol m−2 s−1 at 80°C, followed by acetic acid and DL-lactic acid. Activation energies indicated the initial dissolution in formic acid was diffusion controlled, while kinetic limitations controlled dissolution in acetic and DL-lactic acids. Formic acid showed the best performance for calcium extraction and potential for mineral carbonation.
Boron isotope Ratio as a paleo pH proxyMOHD TARIQUE
This document discusses using boron isotopic ratios to reconstruct past ocean pH and atmospheric CO2 levels. It explains that boron isotopes fractionate between boric acid and borate ions in seawater in a pH-dependent manner, allowing paleo-pH to be determined. The study proposes measuring boron isotopes in carbonate samples from the Southern Ocean and tropical Indian Ocean to reconstruct CO2 variations over geological and modern timescales and understand how ocean acidification may impact marine ecosystems in the future.
- pH is a measure of how acidic or basic a solution is, with values from 0 to 14. Solutions with a pH less than 7 are acidic and greater than 7 are basic.
- The pH scale is determined by international agreement and is based on standard buffer solutions. pH can be measured using a glass electrode and meter or indicators.
- pH is important in many applications including biology, medicine, agriculture and more. It is calculated as the negative logarithm of the hydronium ion concentration.
- For strong acids and bases, pH can be calculated directly from concentration but weak acids and bases require more complex calculations using acid dissociation constants and mass balances.
This study aims to quantify the amount of organic carbon stored in clastic floodplain deposits compared to organic-rich wetland deposits in the Mississippi Delta. Total organic carbon, sediment bulk density, and chronology/accretion rates will be measured from cores taken in Bayou Lafourche, Louisiana. Total organic carbon will be quantified using both loss on ignition and elemental analysis. Sediment texture will be correlated with carbon content. Bulk density and radiocarbon/optically stimulated luminescence dating will provide chronology to calculate annual accumulation rates of organic carbon over time. Comparing storage in floodplains versus wetlands will improve understanding of carbon sequestration in these environments.
The document reports on an experimental study to determine the pKa (acid dissociation constant) of perfluorooctanoic acid (PFOA) using potentiometric titration in a water-methanol mixed solvent system. The study found:
1) The pKa of monomeric PFOA was determined to be 3.8 ± 0.1. This value is important for understanding the environmental fate of PFOA as both its ionized and non-ionized forms have different physicochemical properties.
2) The pKa was suppressed to around 2.3 at higher PFOA concentrations due to aggregation of its conjugate base. Many previous studies measured partitioning coefficients at concentrations above environmental levels,
Carbonate removal from coastal sediments for the determination of organic c a...Mahbubul Hassan
The document compares two methods for removing inorganic carbon from samples to isolate organic carbon for analysis: the aqueous method using hydrochloric acid (HClaq) and the vaporous method using hydrochloric acid vapor (HClvap). It evaluates the methods based on their ability to have low blank levels, efficiently remove dolomite, yield accurate measurements of organic carbon percentage and isotopic signatures (δ13C and Δ14C). The vaporous method met all criteria if samples were not overexposed to acid. The aqueous method gave similar results but was less reliable and consistently underestimated organic carbon percentage. Optimal acid exposure times need to be determined for each sample type to obtain the most accurate isotopic measurements.
This document provides an overview of stable sulfur isotopes. It begins with definitions of isotopes and discusses the four stable isotopes of sulfur - 32S, 33S, 34S, and 36S. It then explains how sulfur isotope ratios are measured using mass spectrometry and discusses some typical isotope variations seen in nature. Applications of sulfur isotopes include tracing sulfur sources in hydrology and studying mantle processes. In conclusion, the document reinforces that sulfur has four stable isotopes and occurs in a variety of geological materials and environments.
Efficiency of Carbonate Precipitation and Removal of Copper and Nickel Ions f...AnuragSingh1049
The effect of pH and initial concentration on the removal of Cu(II) and Ni(II) ions from their monocomponent and two-component aqueous solutions using Na2CO3 as a chemical precipitation agent was investigated in this paper. Monocomponent aqueous solutions of Cu(II) and Ni(II) ions with their initial concentrations of 50 and 500 mg/L and two-component aqueous solution with initial concentration of 500 mg/L were prepared. The precipitation was carried out by batch method at room temperature by stirring the solution at 300 rpm for 5 minutes, resulting in the formation of precipitates. The resulting precipitate was separated by filtration from the solution. The experiment proved that Na2CO3 is a good agent for removing Cu(II) and Ni(II) ions from their monocomponent water solutions of 50 and 500 mg/L concentration and two-component water solution with initial concentration of each metal 500 mg/L. The percentage of Cu(II) removal was higher at lower pH values compared to Ni(II) removal.
Visible light assisted hydrogen generation from complete decomposition of hyd...Pawan Kumar
Hydrogen is considered to be an ideal energy carrier, which produces only water when combined with
oxygen and thus has no detrimental effect on the environment. While the catalytic decomposition of
hydrous hydrazine for the production of hydrogen is well explored, little is known about its photocatalytic
decomposition. The present paper describes a highly efficient photochemical methodology for the production
of hydrogen through the decomposition of aqueous hydrazine using titanium dioxide nanoparticles
modified with a Rh(I) coordinated catechol phosphane ligand (TiO2–Rh) as a photocatalyst under visible
light irradiation. After 12 h of visible light irradiation, the hydrogen yield was 413 μmol g−1 cat with a hydrogen
evolution rate of 34.4 μmol g−1 cat h−1. Unmodified TiO2 nanoparticles offered a hydrogen yield of
83 μmol g−1 cat and a hydrogen evolution rate of only 6.9 μmol g−1 cat h−1. The developed photocatalyst
was robust under the experimental conditions and could be efficiently reused for five subsequent runs
without any significant change in its activity. The higher stability of the photocatalyst is attributed to the
covalent attachment of the Rh complex, whereas the higher activity is believed to be due to the synergistic
mechanism that resulted in better electron transfer from the Rh complex to the conduction band of TiO2.
1) Acid mine drainage is a major water pollution problem in Pennsylvania due to the state's long history of coal mining. When pyrite in coal mines is exposed to air and water, it produces sulfuric acid and dissolved metals that severely degrade water quality and aquatic habitats.
2) Chemical treatment using alkaline substances like limestone is currently the most common method to neutralize acidity and precipitate metals out of the water. However, it is expensive to operate and maintain. Passive treatment methods like constructed wetlands are becoming more widely used because they have lower long-term costs.
3) Wetlands can successfully remediate acid mine drainage through natural processes that raise the pH and remove metals. Pennsylvania is
UCSC Master's Presentation by Wilson SauthoffWilson Sauthoff
The document discusses using nitrogen isotopes of amino acids in marine sediments as a tool to assess changes in organic matter quality and supplied nitrate δ15N over time. It presents results from a study of nitrogen isotope ratios in amino acids extracted from sediment cores collected across a range of depositional environments in the Eastern Tropical Pacific. The study finds that amino acid δ15N patterns are generally well preserved in sediments with lower oxygen exposure times, but become increasingly altered from the original sinking particulate organic matter in sediments with higher oxygen exposure times and more degradation. It also finds that the offset between δ15N of bulk sediments and total hydrolysable amino acids decreases with greater degradation. This has implications for using amino acid δ15N values to
Ocean Acidification: Cause, Impact and mitigationIIT Kanpur
Ocean Acidification and the battle for Carbonate.
In this presentation the points covered are detailed briefing of ocean acidification, its causes, its impact on marine ecosystems and measures to mitigate this.
This document summarizes a study on carbon regeneration in the water column of the Cariaco Basin, Venezuela. The key findings are:
1) Carbon dioxide levels were lowest at the surface (1962 μmol/kg) and increased below the oxic-anoxic redox interface to 2451 μmol/kg.
2) Vertical carbon regeneration was dominated by organic carbon from photosynthetic organisms (82%), with the remaining 18% from biogenic calcite dissolution.
3) The highest organic carbon regeneration occurred in the surface layer consistent with primary productivity, and a secondary maximum (70-80%) was detected at the oxic-anoxic interface driven by chemotrophic microbe respiration
Atlantic Meridional Overturning Circulation Effects on the Carbon Cycle and A...Andreas Schmittner
1) Ice core data suggests that reductions in the Atlantic Meridional Overturning Circulation (AMOC) are associated with increases in atmospheric CO2, as a weaker AMOC reduces the biological pump's ability to sequester carbon in the deep ocean.
2) Early modeling studies showed reductions in the AMOC decrease ocean and land carbon storage, leading to higher atmospheric CO2 levels.
3) More recent models simulate the millennial-scale changes in CO2 observed in ice cores by linking variations in the AMOC to changes in the preformed nutrient inventory and efficiency of the biological pump in sequestering carbon.
Evald Maceno is a graduate student at UPR writing an outline for a class on coastal environments. The document outlines carbon as an element and its physical and chemical properties. It describes carbon as part of a global cycle, moving between the atmosphere, biosphere, lithosphere, and hydrosphere. This carbon cycle is impacted by human activities like burning fossil fuels and deforestation, which increase CO2 levels and acidify the oceans. Rising ocean temperatures and acidification threaten marine life and food systems.
58 S C I E N T I F I C A M E R I C A N M A R C H 2 0 0 6.docxtroutmanboris
58 S C I E N T I F I C A M E R I C A N M A R C H 2 0 0 6
I
n 1956 Roger Revelle and Hans Suess, geochemists at
the Scripps Institution of Oceanography in California,
pointed out the need to measure carbon dioxide in the
air and ocean so as to obtain “a clearer understanding
of the probable climatic effects of the predicted great indus-
trial production of carbon-dioxide over the next 50 years.”
In other words, they wanted to fi gure out how dire the situ-
ation would be today. That they had to argue the importance
of such observations now seems astonishing, but at the time
scientists did not know for certain whether the carbon diox-
ide spewing out of tailpipes and smokestacks would indeed
accumulate in the atmosphere. Some believed that it would
all be absorbed benignly by the sea or be happily taken up by
growing plants on land.
Revelle and the young researcher he hired for this project,
the late Charles David Keeling, realized that they had to set
up equipment at remote locations, far from local sources and
sinks of carbon dioxide, which would cause the measure-
ments to vary erratically. One spot they chose was about as
far from industrial activity and vegetation as anyone could
get: the South Pole. Another was at a newly established
weather station atop Mauna Loa in Hawaii.
The Mauna Loa monitoring has continued (with just one
brief interruption) from 1958 to this day. Being not so remote
as Antarctica, Hawaii sees carbon dioxide levels rise and fall
sharply in step with the Northern Hemisphere’s growing sea-
son, but at the end of each and every year, the concentration
of this heat-trapping gas always ends up higher than it was 12
Much of the carbon dioxide given off from the burning of fossil fuels goes into the ocean, where it changes the
acid balance of seawater. The r eper cussions for marine lif e may be enor mous B Y S C O T T C . D O N E Y
The Dangers of
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COP YRIGHT 2006 SCIENTIFIC A MERIC A N, INC.
w w w . s c i a m . c o m S C I E N T I F I C A M E R I C A N 59
months before. So it did not take long for the scientifi c com-
munity to realize that Revelle was right—much of the carbon
dioxide released into the atmosphere was destined to remain
there. But his calculations were also correct in showing that
a substantial fraction would end up in the sea. And it was clear
to Revelle long ago that the part that went into the ocean would
fundamentally alter the chemistry of seawater. Unlike some
aspects of climate change, the reality of this effect— essentially
the acidifi cation of the ocean—is not much debated, although
its full implications are just now being revealed.
How Unnatural?
t h e h a l f - c e n t u r y r e c o r d that Keeling produced is
extremely valuable, but it is too short to place the current
situation in context. Scientists have, however, been able to
obtain a longer-term perspe.
The carbon regeneration in the water column of
the Cariaco Basin (Venezuela) was investigated
using a regression model of total alkalinity (TA)
and the concentration of total inorganic carbon
(TCO2
). Primary productivity (PP) was determined
from the inorganic carbon fraction assimilated
by phytoplankton and the variation of the 22 and
23°C isotherm was used as an indicator of coastal
upwelling. The results indicate that CO2
levels were
lowest (1962 µmol/kg) at the surface and increased
to 2451 µmol/kg below the oxic-anoxic redox
interface. The vertical regeneration distribution of
carbon was dominated (82%) by organic carbon
originating from the soft tissue of photosynthetic
organisms, whereas 18% originated from the
dissolution of biogenic calcite. The regeneration
of organic carbon was highest in the surface layer
in agreement with the primary productivity values.
However, at the oxic-anoxic interface a second more
intense maximum was detected (70-80%), generated
by chemotrophic respiration of organic material
by microorganisms. The percentages in the anoxic
layers were lower than in the oxic zone because
aerobic decomposition occurs more rapidly than
anaerobic respiration of organic material because
more labile fractions of organic carbon have already
been mineralized in the upper layers.
This study evaluated various bio-optical models for predicting chlorophyll a concentrations in the turbid coastal waters of Long Bay, South Carolina using hyperspectral remote sensing data. Water quality samples were collected from 15 stations during 5 cruises in the summer of 2013. In situ measurements and laboratory analyses were used to determine chlorophyll a, total suspended sediments, and colored dissolved organic matter concentrations. The best performing two-band blue-green model was Oc4v4 with an R2 of 0.64. Red-NIR based models performed even better, with a modified version of the Dekker and Gitelson model achieving the highest R2 of 0.79. This study demonstrated the potential of remote sensing for
C5.04: GO-SHIP: A component of the sustained ocean observing system - Bernade...Blue Planet Symposium
The Global Ocean Ship-based Hydrographic Investigations Program (GO-SHIP) brings together scientists with interests in physical oceanography, the carbon cycle, marine biogeochemistry and ecosystems, and other users and collectors of ocean interior data, and coordinates a network of globally sustained hydrographic sections as part of the global ocean/climate observing system including physical oceanography, the carbon cycle, marine biogeochemistry and ecosystems.
GO-SHIP provides approximately decadal resolution of the changes in inventories of heat, freshwater, carbon, oxygen, nutrients and transient tracers, covering the ocean basins from coast to coast and full depth (top to bottom), with global measurements of the highest required accuracy to detect these changes. The GO-SHIP principal scientific objectives are: (1) understanding and documenting the large-scale ocean water property distributions, their changes, and drivers of those changes, and (2) addressing questions of how a future ocean that will increase in dissolved inorganic carbon, become more acidic and more stratified, and experience changes in circulation and ventilation processes due to global warming and altered water cycle.
This study aimed to understand the behavior of the carbonate system in the Cananéia-Iguape Estuarine-Lagoon Complex
(CIELC) to evaluate its potential as a source or sink for atmospheric CO2. This estuarine-lagoon complex is one of the most
extensive in Brazil, more than 100 km long and covers protected and sparsely inhabited regions of the state of São Paulo. This
system presents, in its southern portion, most preserved areas, and evident anthropogenic impact in the northern portion,
where an artificial canal was created in the second half of the 19th century, with the aim of shortening the navigation path link
the river to the estuarine system offering a passage to the sea, resulting in several modifications, both from a hydrodynamic
and biogeochemical mechanisms. Sampling of salinity (S), temperature (T), total alkalinity (TA), pH, dissolved oxygen (DO),
and nutrients (P and Si) were performed along the CIELC in the winter of 2012 and in the summer of 2013. S, TA, pH and
nutrients were used to support the understanding the behavior of the species in the carbonate system (CO2
, HCO3
-
, CO3
2-)
and related variables were used to calculating the partial pressure of CO2
(pCO2
). The data showed the difference in salinity
and carbonate members distinguished the northern and southern areas, the influence of the marine waters entrance by the
bars, and the predominance of the system as a source of CO2
, even in the most preserved area. However, the difference in this
behavior is most evident under anthropogenic pression offering risk of extreme changes in direction to the southern sector,
now observed until the intermediate point of the system. The recommendation is an urgency in monitoring this region to
minimizes futures environmental changes, as acidification and the increase as a source of CO2
J. Sequeira Ocean Acidification SoA ReviewJohn Sequeira
This document summarizes research on ocean acidification and its effects. It discusses how increased CO2 absorption by oceans leads to acidification, affecting calcium carbonate availability and organisms that use it in shells and skeletons. While most research focuses on single species responses, one study found increased calcification in coccolithophores during winter when pH is lowest, contradicting hypotheses. Experts agree ocean acidification due to CO2 emissions will continue for centuries and exceed past rates, but have less consensus on specific biogeochemical issues.
Assessment of impact of climatic change on groundwater quality around igbokod...Alexander Decker
This document summarizes a study that assessed the impact of coastal saltwater on groundwater quality in Igbokoda, Nigeria. Hydrochemical analysis of 39 groundwater samples found higher concentrations of sodium and chloride ions compared to other ions, indicating influence from saltwater intrusion. While most ion concentrations met drinking water standards, iron and manganese exceeded guidelines in some samples. Ratios of ions like magnesium to calcium and chloride to bicarbonate suggested transformation of fresh groundwater to brackish water in parts of the aquifer due to saltwater mixing. The dominant groundwater type was characterized as sodium-chloride, reflecting saltwater influence, along with some calcium-bicarbonate freshwater sources.
This document provides an overview of the global carbon cycle and the role of inland waters. It discusses carbon pools and fluxes at different time scales, from the modern perturbed cycle to pre-anthropocene, glacial-interglacial, and Earth's history. The key role of the ocean in regulating atmospheric CO2 levels over the past 10,000 years is explained through calculations showing that net heterotrophy in the ocean could account for the required imbalance. Links between the carbon and oxygen cycles through geological time are also briefly outlined.
The document discusses the importance of monitoring land-ocean carbon fluxes at a pan-European scale. It notes that while there is a significant amount of existing data on carbon fluxes, the data is scattered and not standardized. The document recommends establishing a coordinated monitoring network that builds on existing water quality monitoring networks to regularly measure carbon and other parameters in Europe's major rivers, lakes, and coastal waters. Targeted process studies and numerical modeling could help extrapolate the monitoring data and further scientific understanding of carbon fluxes across the land-ocean continuum.
gas hydrates Natural hazards or Natural resourcesKushank Bajaj
Hydrates are ice-like crystalline structures that form under high pressure and low temperatures and contain a gas, such as methane, trapped within a lattice of water molecules. They are found in marine sediments along continental margins and in permafrost regions. There are two main hydrate structures that differ in the arrangement of cavities containing the trapped gas. Hydrates are a potential future energy resource and also impact sea floor stability and global climate change through methane release. Study of hydrates at Hydrate Ridge off the Oregon coast provides insights into their occurrence, identification, and natural resource potential. Large quantities of hydrates in marine and permafrost deposits have the potential to release methane and amplify climate change if triggered by various
This document summarizes the results of analyzing strontium isotope ratios (87Sr/86Sr) in pore water samples collected during Integrated Ocean Drilling Program Expedition 337 off Shimokita peninsula, Japan between 1289 to 2405 meters below seafloor. The ratios suggest mixing between ancient seawater and fluids derived from volcanic material alteration, as confirmed by smear slide observations showing weathered volcanic material. Ratios ranged from 0.7086 to 0.7061, with volcanic materials from the region having similar ratios to measurements at deeper levels, suggesting volcanic alteration is a source of fluids supporting deep microbial life in the area.
The oceans are getting acidified! How? Why? What can we do?
For answers... Check the Presentation out
(Just a bit more informative than my previous one)
An investigation on role of salinity, pH and DO on heavy metals elimination t...GJESM Publication
One of the most paramount processes that play a considerable role in reducing the concentration of
heavy metals during estuarine mixing is flocculation. Not only does such a process cause a huge percentage of metals to come into the particulate phase, but also it provides ample nutrients for the aquatic life. In the present study, impact of such factors as salinity, pH and DO on flocculation of Cu, Zn, Pb, Ni, Cd and Mn throughout mixing of Chaluse River with Caspian Sea is investigated. The trend of flocculation of Pb (24.32%) < Zn (24.38%) < Cd (40.00%) < Cu (64.71%) < Ni (68.00%) < Mn (76.47%) reveals that among the studied elements Mn and lead experience minimum and maximum flocculation at diverse salinity regimes, respectively. Moreover, flocculation rate of studied metals fluctuates between 24.32 and 76.47 percent. It is interesting to note that much of metal flocculation occurs at the very lower (less than 2 ppt) salinity regimes.
1. Marine biomarkers can be used to reconstruct past changes in phytoplankton composition and productivity, which can provide insights into biological mediation of CO2 sequestration over time.
2. Comparisons of biomarkers like alkenones and brassicasterol can indicate shifts between coccolithophores and diatoms, while multi-proxy records using biomarkers and isotopes can reconstruct surface ocean productivity, dust inputs, and thermocline conditions.
3. Biomarkers have advantages in predicting past and future atmospheric CO2 levels but also limitations like not fully explaining expected shifts in phytoplankton groups or accounting for changes in the carbonate pump.
Soma Sekhar Sriadibhatla presented on the effects of increasing carbon dioxide levels in the environment and methods of sequestering carbon dioxide. The presentation discussed how rising CO2 levels are leading to global warming and ocean acidification. Testing of water samples from Visakhapatnam, India found decreasing pH levels and carbonate ion concentrations over time, indicating ongoing ocean acidification. The presentation proposed carbon dioxide sequestration techniques including reversible adsorption and discussed using captured CO2 for commercial purposes like enhanced oil recovery. It concluded more must be done to regulate CO2 emissions and deal with issues like global warming and ocean acidification.
Similar to Coppola_et_al-2016-Geophysical_Research_Letters (20)
2. Western Arctic samples from the Beaufort Sea (~3650–3825 m deep) were collected from adjacent stations
(Stn. 40 and 41, 19.4 km apart) taken in October 2012 aboard the R/V Healy. A coastal Arctic sample (from
125 to 175 m depths) was also collected. A northeast Atlantic surface (50 m) sample was collected in
October 2013 on the A16 cruise aboard the R/V Brown. Two deep (1135–2290 m) and one surface (50 m)
sample were collected in the North Atlantic from the Sargasso Sea in April 2012 on the A22 cruise aboard
the R/V Atlantis. The deep Sargasso Sea samples were collected from adjacent stations (Stn. 26 and 27,
83.0 km apart) and were processed separately for DBC concentration and combined for a single DBC
Δ14
C measurement. A south Atlantic surface (50 m) sample was collected in October 2011 on the A10
cruise aboard the NOAA Ship Ronald H. Brown.
All samples were collected in Niskin bottles that had been cleaned at the beginning of each cruise with a
dilute detergent solution and 10% hydrochloric acid. Surface samples were filtered using Whatman GF/F
filters (0.7 μm) that had been combusted at 500°C for 2 h. All metal and glassware used in this study was
cleaned, acidified in 10% HCl, rinsed with deionized water, and combusted for 2 h at 500°C before use to
remove inorganic and organic carbon. DOC samples were collected in 1 L amber glass bottles and DBC
samples were collected in 3.785 L, clear glass bottles. All seawater samples were frozen (at À20°C, at an angle
to avoid breakage) until analysis in the laboratory at University of California Irvine.
2.2. SPE-DOC and Total DOC Concentrations
Seawater samples were measured separately for total DOC (using UV oxidation [Beaupre et al., 2007]) and
for SPE-DOC [Coppola et al., 2015]. Briefly, SPE-DOC was extracted from large-volume filtered water samples
(10–15L for surface and 25 L for deep) that had been acidified to pH2 (using hydrocholoric acid, analytical
grade) and siphoned through a styrene divinyl benzene copolymer resin (Sigma Aldrich Diaion 13605, HP-20,
pore size 200 Å) column at a slow loading rate (two bed volumes per hour, 240 mLhÀ1
) [Coppola et al.,
2015]. In preparation for DOC elution, two bed volumes (30 mL) of Milli-Q water were passed through the col-
umn to remove salts and was discarded. SPE-DOC was eluted with methanol into precombusted glass vials and
dried under a stream of ultrahigh purity (UHP) nitrogen gas. SPE-DOC samples were stored at À20°C until
BPCA analysis.
2.3. DBC
DBC was quantified in the SPE-DOC methanol extracts as aromatic marker compounds (benzene polycarboxylic
acids, BPCAs) from a high temperature and pressure acid digestion (BPCA method) [Coppola et al., 2013;
Ziolkowski et al., 2011]. Briefly, SPE-DOC extracts were dried and lyophilized for 24h. Concentrated nitric acid
was added to the sample in a quartz pressure digestion chamber that was heated to 170°C for 8 h to produce
BPCAs. After digestion, the solution was filtered, lyophilized, and redissolved in methanol. Samples were deri-
vatized using (trimethylsilyl) diazomethane in 2.0 M diethyl ether to convert carboxylic acid groups to methyl
esters, and an internal standard was added (diphenic acid). BPCAs were collected on the preparative capillary
gas chromatograph (PCGC Hewlett Packard 6890 GC) equipped with an HP 7683B autoinjector, Gerstel cooled
injection system (CIS-4) with split/splitless inlet, and a DB-XLB capillary column (30 m Å ~ 0.53 mm ID, 1.5m film
thickness CP-Sil 8CB Ultimetal column). Calibration curves were made using commercially available BPCAs to
quantify the BPCAs measured from peak areas obtained from the flame ionization detector chromatographs.
The BPCA method requires a conversion factor to convert the BPCAs formed from the nitric acid digestion into
an estimate of the original BC mass. A DBC recovery factor of 23.2± 0.4% was used for the conversion of BPCAs
to BC [Ziolkowski and Druffel, 2009; Ziolkowski et al., 2011]. This conversion factor was used because it was
determined from oxidizing compounds with known chemical formulas (polycyclic aromatic hydrocarbons) to
calibrate the BPCA method for carbon yield. Previously used conversion factors were based on yields from
activated charcoal where the chemical formula was unknown [Brodowski et al., 2005; Glaser et al., 1998].
For Δ14
C analysis, B3CA through B6CA marker compounds (including nitrated B3CAs and B4CAs) were
collected in U-traps (À20°C) in the fraction collector of the PCGC. The B2CA marker compounds were not
collected, because they are also derived from aromatic compounds of noncombusted origin (e.g., lignin).
Each BPCA may have a unique Δ14
C value. However, samples were too small to measure individual BPCA
Δ14
C values. The BPCAs in the U-trap were transferred using dichloromethane to quartz tubes and dried
under UHP nitrogen gas for isotopic analyses.
Geophysical Research Letters 10.1002/2016GL068574
COPPOLA AND DRUFFEL CYCLING OF BLACK CARBON IN THE OCEAN 2
3. 2.4. Radiocarbon Analysis
Samples were sealed in quartz tubes under vacuum with cupric oxide and silver wire and combusted to CO2
at 850°C for 2 h. The CO2 was cryogenically purified, quantified manometrically, and reduced to graphite
using a hydrogen reduction method for small samples [Santos et al., 2007]. Radiocarbon measurements were
made at the University of California Irvine Keck Carbon Cycle Accelerator Mass Spectrometry Laboratory and
are reported as Δ14
C (and conventional 14
C age) for geochemical samples without known age [Stuiver and
Polach, 1977]. Stable carbon isotopes (δ13
C) were measured on equilibrated splits of CO2 from a subset of
the DOC and SPE-DOC samples using a Gas Bench II and Thermo Electron Delta Plus mass spectrometer with
an uncertainty of ±0.2‰. Stable carbon isotopes were not measured on BPCAs due to the small sample sizes.
3. Results
We obtained surface DBC Δ14
C values that ranged from À116 ± 162 (Sargasso Sea) to À824 ± 5‰ (coastal
Arctic) (Figure 1a and Table S2). The average surface DBC Δ14
C value for open ocean samples was À450
± 42‰ (4800 ± 620 14
C years, n = 6). The coastal Arctic sample was excluded in this average because it was
Figure 1. (a) Δ
14
C values of solid phase extracted dissolved organic carbon (SPE-DOC, red dashes), total dissolved organic
carbon (DOC, blue dashes), and dissolved black carbon (DBC, black squares) samples. All samples are from the surface,
except the deep Sargasso Sea sample. The average DBC Δ
14
C value for the surface ocean (excluding the coastal Arctic) is
À450 ± 42‰ and is displayed as the grey box. (b) DBC concentration values. The average DBC concentration for the surface
samples is 1.6 ± 0.1 μM and is displayed as the grey box. (c) Relative BPCA abundances in each DBC sample.
Geophysical Research Letters 10.1002/2016GL068574
COPPOLA AND DRUFFEL CYCLING OF BLACK CARBON IN THE OCEAN 3
4. not an open ocean sample. The deep Sargasso Sea sample had the lowest DBC Δ14
C value (À945± 6‰; 23,000
± 3000 14
C years) obtained in this study.
In contrast, the surface SPE-DOC Δ14
C measurements (Figure 1a) ranged from À290 ± 3 in the coastal Arctic
to À338 ± 4‰ in the Sargasso Sea. The Beaufort Sea SPE-DOC Δ14
C values from adjacent stations were iden-
tical (À294 ± 4 and À299 ± 4‰). The northeast Atlantic, Sargasso Sea, and south Atlantic SPE-DOC Δ14
C
values were also identical (À330 ± 4, À338 ± 4, and À335 ± 7‰, respectively). Two deep Sargasso Sea sam-
ples at Stn. 26 and Stn. 27 had significantly different values (À382 ± 4 and À408 ± 4‰, respectively).
The relatively narrow range of SPE-DOC Δ14
C values is comparable to the range of total DOC Δ14
C values
obtained for these samples (Table S2). Surface total DOC Δ14
C measurements (Table S2 and Figure 1a) ranged
from À255 ± 4‰ in the Sargasso Sea to À311 ± 4‰ in the Beaufort Sea, respectively. The total DOC Δ14
C
values are significantly higher than their requisite SPE-DOC Δ14
C values for four samples, significantly lower
for one sample (Beaufort Sea, Stn. 41) and the same for one sample (Sargasso Sea, Stn. 26).
The concentrations of DOC in the surface samples ranged from 53.8 to 71.8 μM (Table S2). The DOC concen-
tration in the deep Sargasso Sea was 42.1 μM. These values are within error of DOC concentrations reported
by Hansell et al. [2009]. The recovery for marine SPE-DOC was 43 ± 2%, which is within error of the recovery
reported by Dittmar [2008] using a similar resin. Surface SPE-DOC concentrations ranged from 25.9 to 32.0 μM
(Table S2). The deep Sargasso Sea SPE-DOC concentrations at adjacent stations were 22.1 and 23.5 μM.
DBC in the surface samples ranged from 1.4 to 2.6 μM. The lowest surface DBC concentration was in the
northeast Pacific, while the highest were in the Beaufort Sea and south Atlantic (2.6 ± 0.9 and 2.5 ± 0.4 μM,
respectively). The average surface DBC concentration was 1.6 ± 0.1 μM (n = 6). The average DBC concentration
of two deep Sargasso Sea samples was 1.2 ± 0.1 μM.
For most DBC samples, B3CAs and B4CAs were more abundant than the B5CAs and B6CAs (Figure 1c). B5CA
and B6CA marker compounds (which are indicative of highly aromatic, condensed BC), constituted 15–30%
of the BPCAs quantified. Higher relative abundances of B3CAs were observed in the northeast Pacific and
south Atlantic samples.
4. Discussion
It was hypothesized that DBC was the ancient component responsible for the low Δ14
C values of total DOC
[Ziolkowski and Druffel, 2010; Masiello and Druffel, 1998]. We find that the concentration and Δ14
C value of
DBC in the deep Sargasso Sea (1.2 μM and À945‰) does not explain the low Δ14
C value of SPE-DOC
(20 μM and À395‰). If DBC was not present in SPE-DOC, the Δ14
C of SPE-DOC in the deep Sargasso Sea sam-
ple would be À360‰, which is only 35‰ higher than its present value (À395‰ = (1.2 μM/20 μM)*(À945‰)
+ (18.8 μM/20 μM)*x). Clearly, other 14
C-depleted components besides DBC must be present to account for
the great 14
C age of DOC.
Importantly, our data reveal that there is a minimum of two pools of DBC in the ocean, each with its own 14
C
age. It is not possible to model DBC as a homogenous pool with a single Δ14
C value (supporting information,
Text S1, Figure S3, and Figure S4). Using a simple mass balance, the surface ocean average value (À450‰)
can be obtained from a mixture of postbomb DBC (+1035 ± 521‰ = x) and the deep Sargasso Sea DBC
(À945 ± 6‰) (À450‰ = (0.4 μM/1.6 μM)*x + (1.2 μM/1.6 μM)*(À945‰)).
DBC entering the ocean from rivers and aerosols have different physical properties and structures than those
in the ocean, which likely affect their residence times [Ding et al., 2015; Safai et al., 2014; Santin et al., 2015].
For example, land-derived BC may be more important in some regions (e.g., Arctic) than in others (e.g., South
Pacific) [Stubbins et al., 2015], and we hypothesize that it may contain more bomb 14
C. The second pool is an
ancient, more stable DBC pool (>20,000 14
C years) that likely predominates in the deep ocean [Ziolkowski and
Druffel, 2010].
Simple mixing of two isotopically different components of DOC was reported earlier [Druffel et al., 1992; Williams
and Druffel, 1987]. Specifically, mixing of a labile DOC pool at the surface (from primary production), with aged
DOC from deep water explains the total DOC concentrations and Δ14
C values in the surface waters of the
Sargasso Sea, Mid-Atlantic Bight, north central, and northeastern Pacific [Bauer et al., 1998; Druffel et al., 1992;
Geophysical Research Letters 10.1002/2016GL068574
COPPOLA AND DRUFFEL CYCLING OF BLACK CARBON IN THE OCEAN 4
5. Williams and Druffel, 1987] (supporting information Text S1). Two-component mixing is also observed for BC in
soils, where there are two BC pools with distinct chemical compositions and residence times [Bird et al., 2015;
Knicker et al., 2013; Singh et al., 2012, 2014b]. Because oceanic DBC is coupled to riverine DOC export globally
[Ding et al., 2015; Jaffe et al., 2013; Wagner et al., 2015], DBC pools with different structures and 14
C ages may
be preserved in the ocean and may explain the two DBC pools that we observe.
If we assume that the global ocean has similar DBC and SPE-DOC concentrations as those found in our study,
the mass of DBC in the global SPE-DOC pool would be 14 ± 2 Gt C (662 Gt C*0.43*0.05 = 14 Gt C). This value is
similar to a previous estimate (12 Gt) [Dittmar and Paeng, 2009]. This technique, which encompasses SPE
extraction through oxidation, extraction, and quantification of the BPCA derivatives from DBC, provides a
conservative estimate of the total DBC mass.
Our estimate of DBC mass does not include 57% of the total DOC pool, given that 43% of the DOC was sorbed
onto the SPE resin and quantified. The distribution of DBC in total DOC has not been measured. If DBC is
equally distributed in the non-SPE-DOC pool, then our estimate of the mass of DBC in the global DOC pool
is 32 ± 4 Gt DBC (662 Gt DOC*0.05). This value would require modification if BC is unequally distributed in
DOC as an Arctic river study and a natural organic matter Suwannee River standard assessment suggest
[Wagner and Jaffe, 2015; Coppola et al., 2015]. DBC in SPE-DOC isolates are more aromatically condensed
and may have higher Δ14
C values than those of DBC from the total DBC pool [Coppola et al., 2015]. It is highly
likely that there is discreet cycling of DBC within these DOC fractions isolated by different techniques.
Nonetheless, a larger sample set and comparisons of BC isolated in various size fractions and using different
SPE techniques are needed to quantify the relationship of DBC in DOC.
Our study presents the first assessment of SPE-extracted DBC 14
C ages in ocean water. Each year, rivers
transport 0.0265 ± 0.0018 Gt DBC to the oceans [Jaffe et al., 2013]. Atmospheric deposition is a smaller source
of BC to the ocean, ranging from 0.002 to 0.006Gt DBC per year in the Northern Hemisphere [Jurado et al.,
2008]. The input by rivers is sufficient to sustain the turnover of the entire DBC pool in 500 14
C years, yet 14
C
ages are 40 times higher for DBC in the deep sea. We estimate that the amount of DBC in the SPE-DOC is
low, 14± 2 Gt C, with old 14
C ages in the surface (4800 ± 620 14
C years) and deep (23,000 ± 3000 14
C years)
ocean. This suggests that despite its polyaromatic structure, most BC delivered via rivers is not accumulating
in the ocean. Therefore, loss processes, such as UV oxidation and microbial degradation, may be important
for altering and removing DBC [Stubbins et al., 2012]. Additionally, with recent increases of burning of fossil fuels
and biomass, DBC export from river systems will continue to rise [Randerson et al., 2012]. Riverine and atmo-
spheric DBC Δ14
C, structure, and concentration measurements will help to understand the input and fate of
DBC into the DOC pool from watersheds to the deep ocean.
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Acknowledgments
We thank Steve Beaupré and Sheila Griffin
for collecting Station M DOC water sam-
ples and the technicians and crew of the
R/V New Horizon (November 2004) for
assistance at sea. We also thank Molly
Barringer, Ruth Curry, technicians, and
crew of the R/V Atlantis (April 2012) and
NOAAS Ronald Brown (November 2011),
Sheila Griffin for her technical support
and assistance, Brett Walker and Francois
Primeau for their technical expertise and
discussions, Dachun Zhang for his help
with the PCGC and guidance, Xiaomei Xu
for her help with
14
C corrections,
Christopher Glynn for laboratory help,
John Southon, Guaciara Santos, and the
Keck Carbon Cycle AMS Laboratory col-
leagues for AMS support. We thank
Claudia Czimczik, Eric Saltzman, Michael
Schmidt, Lori Ziolkowski, Brett Walker,
and Robert Letscher for comments on an
earlier version of the manuscript. We
acknowledge support from NSF (OCE-
0961980, OCE-1022716, and OCE-
1458941), the NSF/NOAA-funded U.S.
Repeat Hydrography Program and the
Fred Kavli Foundation. We thank two
anonymous reviewers who improved the
quality of the manuscript.
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