Heavy metals contamination at whitespots – conlig, newtownards, northern ireland.


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Heavy metals contamination at whitespots – conlig, newtownards, northern ireland.

  1. 1. Journal of Natural Sciences Research www.iiste.orgISSN 2224-3186 (Paper) ISSN 2225-0921 (Online)Vol.3, No.5, 201345Heavy metals contamination at Whitespots – Conlig,Newtownards, Northern Ireland.Chukwuemeka Kingsley Egbuna 1*Bolarinwa Ajibola 2Ishaq Ayoola Louis31. Department of Civil Engineering, University of Bristol, UK2. Department of Geology, University of Brighton, UK3. School of Built Environment, University of Brighton, UK*Email of corresponding author: cke12402@bristol.ac.ukAbstractThis study was conducted to investigate and examine the dispersion of heavy metals at the lead mine ofWhitespots – Conlig, Newtownards, Northern Ireland. Seven vertical profiles namely; profiles A, B, C, D, E, Fand G, were measured at depths between 0cm to 80cm and were tested for soil moisture content, soil pH, PXRFspectrometer, XRD spectrometer and Inductively Coupled Plasma Mass spectrometer (ICP-MS), with all testsdone in duplicate. The finding shows that Pb and other heavy metals accumulate at the topsoil of profiles B 0-22cm, C 0-20cm and A to depth 63cm. The process of dispersion occurs as lateral migration of contaminatedmaterials, which partly accumulated at topsoil via surface runoff across the meadow. This process is regulated bythe clay-rich and organic-rich soil composition, the soil pH condition of neutral to slightly alkaline whichallowed immobilized Pb and other heavy metals to be adsorbed onto soil particles and a small percentage ofleaching to take place. The mobile elements K, Fe and Zn which percolated downward were howeverprecipitated in the slightly alkaline to neutral soil. The concentration of the carbonates and heavy metalsindicated a lateral dispersion process by surface flow transfers and deposition of particles via an entry point ontothe field and also as a result of topographic gradient.Keyword: Lead, PXRF, minerals, metals, DTPA Extraction1.0 IntroductionElevated levels of heavy metals from metalliferous mines are found in and around disused mines sites due todischarge and dispersion of mine wastes into the ecosystem (Alloway, 1995; Jung, 2001). Heavy metals whichare contained in residues of mining and metallurgical operations are frequently dispersed by wind and or waterafter their disposal (Adriano, 2001). These areas experience severe erosion problems caused by wind and waterrunoff and to which soil texture, landscape topography; regional and micro-climate operate an important role(Chopin et al., 2003 and Razo et al., 2004).The contamination of soil by Pb and other heavy metals in and around a mine site is dependent on thegeochemical characteristics and the extent and degree of mineralization of the tailings (Johnson et al., 2000). Therelease of metals by sulphide oxidation is weakened by precipitation, sorption reactions and co-precipitation(McGregor et al., 1998 and Berg et al., 2001) in and around the site. The dispersions of these metals released andtheir inputs into soil profile and sediments (Kim et al., 2002) are subjected to examination as well as the physicaltransport process involved (Navarro et al., 2007). It has been established that bio-availability of heavy in soils isdependent on the solubility of minerals and chemical species present (Kambata-Pendias and Pendias, 1984),hence, soil pH and soil buffering capacity appear to be important controls on metal bio-availability (Alloway,1990; Gee et al., 2001). Pb contamination can cause health problems via ingestion and or inhalation to plants andhumans because of its organic compounds which are toxic. This paper thus, investigates and examines thedispersion of heavy metals at the lead mine of Whitespots – Conlig, Newtownards, Northern Ireland.2.0 Study MaterialsSite studyThe Whitespots – Conlig lead mines is an abandoned mine site near Newtownards, Northern Ireland, whichoccupies an extensive area consisting of spoil heaps, tailings impoundments, capped mine shafts as well as thearchitectural features of the engine house and chimney stacks. The mine site contains materials such ashydrothermal vein minerals, notably galena, chalcopyrite, barite, dolomite, calcite and harmotome which help toidentify the origin of its mineralization (Nawaz and Moles, 2006).Previous studies at a metalliferous mine site shows the accumulation of Pb as well as other heavy metals insurrounding soils (Sidle et al., 1991) vegetation (Johnson and Eaton, 1980; Chambers and Sidle, 1991), localwater ways (Merrington and Alloway, 1994), and of this mine site, uptake of heavy metals by plant andtranslocation to human food chain (Levy et al., 1992).In recent times, the Department of the Environment for Northern Ireland after due consultation with the Councilfor Nature Conservation and Countryside, decided to make the mine area an area of special scientific interest by
  2. 2. Journal of Natural Sciences Research www.iiste.orgISSN 2224-3186 (Paper) ISSN 2225-0921 (Online)Vol.3, No.5, 201346reason of geological features, hence declaring it to be ‘Whitespots Area of Special Scientific Interest’ (Martin,1998) and also develop it as a country park (Moles et al., 2004).3.0 MethodologySeven vertical profiles namely; profiles A, B, C, D, E, F and G, were measured at depths between 0cm to 80cm.Profile G is at a near-by field where previous work had also been done and it is intended to give a backgroundrepresentation of the field contaminated by heavy metals. These profiles were analysed for XRD, DTPA, PXRFand soil moisture content and pH. All tests were done in duplicates and it was observed that the variationsbetween both results were not more than 2%.The XRD is a method for characterising the mineralogy of rocks and soils and can be used to derive quantitativemineralogy data. The soil samples were homogenised, oven dried and ground to particles of about 0.002mm. It isimportant to have a finely ground sample with a flat surface so that the XRD accurately measures the molecularstructure or compound of the soil sample. Semi-quantitative estimates of the proportions of mineral constituentsof the soil samples are obtained in percentages by the computer program X’Pert Pro.Di-ethylene-triamine penta-acetic acid (DTPA) is a soil test which is useful to extract the portion of Zn, Fe, Mnand Cu which is similar to the amounts that are bio-available in the soil. Heavy metals have higher affinity forchelating agent than soil, hence, metal contaminants dissolve during the extraction process (Hong et al., 2002).This is because the chelating agent combines with free metal ions in solution and as such forming solublecomplexes, thus, reducing activities of free ions in solution. Accumulation of chelated metals in the solution isan indication of extraction function of both ability of metal ions in soil and ability of soil to replenish those ions.The purpose of using the DTPA is to dissolve certain heavy metals by preventing through precipitation theirremoval and then release the absorbed metals that are in sediments of the soil.The Portable X-ray Fluorescence spectrometry (PXRF) is used for analysing the elemental composition of rocksand sediments (Jenkins, 1999). Its analysis is derived from excitation of electrons by incident X-radiation. Theenergy emitted as fluorescence and the wavelength spectra forms the characteristics of atoms of specificelements (Weltje and Tjallingii, 2008). The instrument is used for both in-situ and ex-situ methods of analysis.The processed data output reveals the minerals with highest concentration within the threshold of soil sampleanalysed (Ramsey and Boon, 2011).4.0 Results4.1 Soil Moisture content and soil pHThe range of soil pH and its moisture content of 44 soil samples over the 7 profiles are shown in table 1. The soilpH range indicates most of the soil sample content is neutral and a deviation between slightly alkaline to slightlyacidic as it is location dependent. The classification of the pH values deduced plays an important role in themobility of metals in the soil, this is because they govern directly or indirectly the complex reactions of metalcations, ion –exchange as well as other metal binding formations and solubility. Profiles A and C are mainlyneutral while profiles B, D, E, F indicate a shift towards slightly alkaline depth soils as a result of ingress ofcarbonate – rich tailings material into the meadow. Profile G, is neutral to slightly acidic and its location is at abackground representative location to the field and by contrast cannot be affected by the carbonate materialsfrom the tailings spoil heaps.All the profiles (A-G) have variations in distribution of soil moisture, the profile A is most characterised byclayey soil texture, and has a very high dry mass of 45% in core depth 57cm-63cm. At this depth the soil is lightbrown clay and its moisture characterisation indicates it is moderately plastic when wet, hence, it is close to thefield capacity after gravitational percolation has taken place. By indication of this, the water content is not onlystored for plant use but also as an agent of metal transportation within the soil. This can also be described for thehighest moisture content depth profile D 37cm-50cm with weight loss of 52% indicating moisture content isabove field capacity, which results from the nearness of the depth profile to the close-by spring.4.2 Portable X-ray Fluorescence spectrometry (PXRF)The data obtained via the PXRF in-situ and ex-situ analysis indicated 17 elements and 20 elements respectively.For the in-situ data, 2 elements (S and As) were measured below detection limit while ex-situ data, 8 elements(S, Co, As, Rb, Sr, Zr, Cd, Sn) were measured from no data to below detection limit and above detection limits.Correlation between the data results of in-situ and ex-situ analysis varies with disparity as low as 3ppm (profileG, Cu) and as high as 38,953ppm (profile B, Pb). The variation in values encountered by the output data isshown in table 2.The variations in the ppm values between the in-situ and ex-situ data could be attributed to some inherentinterference which caused disturbances to the detection limits and precision use of the instruments. Thisinterferences is as a result of the particle size, homogeneity, and surface conditions of the soil for in situmeasurements and moisture content, grinding of air-dried soil sample, chemical matrix effect (for example when
  3. 3. Journal of Natural Sciences Research www.iiste.orgISSN 2224-3186 (Paper) ISSN 2225-0921 (Online)Vol.3, No.5, 201347Fe will absorb more Cu X-rays, thus making Cu levels enhanced in the presence of Fe (Mclean and Bledsoe,2004) and precipitation.4.2.1 In situThe variations in trends of elements measured by the PXRF shows that Pb (68093ppm) and Ca (56751ppm)recorded highest in the topsoil of profile B, but gradually decreases between depth 20-30cm down the verticalprofile. Fe records 24107ppm at the topsoil but shows variations with distributions in depths as it movesdownward the profile. K, Zn and Cu recorded highest measurements of 10815ppm, 2049ppm and 586ppmrespectively (fig. 1). Fe recorded the highest reading 28398ppm at depth 20cm of the profile with least reading13761ppm recorded for depth 50cm. Ca and K exhibit similar trend patterns with varying measurements. Atdepth 50cm the least readings were observed for Ca 3715ppm and K 4180ppm. Pb, Zn and Cu had low readingswithin this depth profile (fig. 2).4.2.2 Ex situThe processed laboratory graphic analyses of soil samples were splited into two to show clearly the visibleelements and the variations within the depth profiles.The processed output of the PXRF spectrometer indicates a very high detection of Pb and Ca in profile A and agradual decrease in profile B. This detection of metals gradually decreases along the other profiles. Fe appearsalthough low but with a 40000ppm as its highest detection and a constant variable in all the depth profiles.Profile A is closest to the entrance of the tailings wash onto the field hence the major factor for highest detectionby the PXRF spectrometry. As the variables of the metals decrease across the excavated transect, it should benoted that elements with little detections by the spectrometer is as a result of the detection limits of the analyser.It therefore means that these elements with little or no detection, for example profile D where detection limits ofCu, Zn and Pb, it would simply mean the elements have low values (ppm) that are not considered to be read-ableby the spectrometer. Rainwater and surface wash of the tailings are the prime form of deposition of these heavymetals across the different depth profiles of the soil (figures 3 and 4).4.3 XRD spectrometryMinerals detected by the X-ray diffraction spectrometry are quartz, cerussite, calcite, dolomite, clinochlore,plagioclase. Clinochlore ((Mg,Fe2+)5AI(Si3AI)O10(OH)8), from mineralogy group of chlorite, is derived fromcountry rock, that is greywacke and shale which was metamorphosed to form chlorite together with mica (butnot shown by XRD analysis) and attains the highest semiquant of 100%. The clinochlore and the quartz arederived in the parent material of the soil, as such the constituent of high detection by the XRD machine. ProfilesA, B, and C differ in terms of mineral proportion to profiles D, E and F, and while profile G as well as in depictsin abundance of the detected minerals. The cerussite, calcite and dolomite are discharged into the soil mainlyfrom the source which is the tailings wash from the adjacent spoil heaps. This can be described given that inprofile A the contaminant (calcite) can be seen while it in other profiles may have possibly dissolved belowdetection limits in other profiles. They are all carbonate minerals, yet they posses different solubility such thatcalcite mineral readily dissolves than dolomite and cerussite with the use of rainwater percolating into the soil(figures 5 and 6).Plagioclase is another mineral forming the parent material of the soil. This mineral was detected by the XRDspectrometer, the mineral indicates variations in proportions, however its detection can be seen in profile Adepth 57-80cm, while in profile B detection was further closer to the topsoil than profile B 28-76cm. Profile C isof the same pattern as to profile B, and detection was also seen closer to the topsoil at depths 20cm to 70cm ofthe soil profile. All other profiles had detection from the topsoil to beneath the depth profiles.4.4 DTPA ExtractionThe selected soil depth samples analysed were chosen based on the wide variations in proportion of distributedheavy metals within the depth profiles. Due to time constraints the ICP spectrometer was used as against the useof AAS however, the existing literature by Lindsay and Norvell, (1978) did specify the use of AAS andappropriate standards. The concentrations of Pb, Fe, K, and Cu are highlighted in table 3. The result indicatedshows a high bio-availability of Pb in the entire depth profiles within the soil sampled as it decreased fromprofile A depth 50-57cm (86mg/l), 57-63cm (62mg/l), to 63-68cm (35mg/l). This can also be described for Kand Cu whereas Fe only had concentrations at depth 57-63cm (1mg/l) and 63-68cm (8mg/l).At profile B, Pb and Fe concentrations increased from sampled depth 16-22cm; to 22-28cm; 125mg/l to 143mg/land 0mg/l to 4mg/l respectively, while K and Cu decreased from 14mg/l to 12mg/l and 13mg/l to 5mg/lrespectively as well. Profile C experiences a variation in proportion of the heavy metals in the sampled depthprofiles. Depth 17-20cm denotes the highest concentration of Pb, 0-9cm for K and Fe while 9-17cm for Cu. Fehas no concentration in depth 9-17cm and it took an increase in depth 17 to 27cm from 2mg/l to 8mg/l. Profile Ehad concentrations of from the top sampled soil depth in Pb 106mg/l and K 12mg/l and decreased into the 19-
  4. 4. Journal of Natural Sciences Research www.iiste.orgISSN 2224-3186 (Paper) ISSN 2225-0921 (Online)Vol.3, No.5, 20134829cm however, from 9-19cm to 19-29cm there was an increase from 16mg/l and 3mg/l to 19mg/l to 4mg/l for Feand Cu respectively.5.0 DiscussionThe results obtained for soil moisture contents shows a wide variation with the soil profile of the meadow. Eachprofile experiences an irregular sequence in moisture content distribution. This however, could be attributed tothe amount of water incorporated within the soil pores, soil composition, and retention capacity. The result of thepH values of water are in slight contrast to the findings of Moles et al., (2004) which differ on the range ofsample classification. In Moles et al. findings, pH values range between 6.6-8.1 which reveals they were neutralto slightly alkaline while the findings from samples analysed in this study, shows pH value range between 6.23-7.54 indicating slightly acidic to slightly alkaline water content. This however shows a change in solubility ofcerussite which although have fine grain size, yet, have existed in the tailings materials for over 150 years(Moles et al., 2004).The source of the contaminated soil is the lead rich tailings which have undergone erosion by wind, rain andvisibly scrambling at the surface; thus causing re-distribution of metal particulates or soluble metals to pollutethe surrounding surface soils and vertical depth profiles. Currently, the tailings material is deposited in thedepositional plume in a meadow on the south side of the site (Moles et al., 2000). The dispersion of heavy metalshave moved in from the entry point across the field and percolated into the soil profile core depths. The coredepth profiles investigated and examined is in agreement to Moles et al., (2004) findings which reveal thatvertical depth 0-20cm of profiles A, B and C are contaminated by the mechanically redistributed tailingsmaterial. However, at core depths 22cm downward the profiles B-F depicts they are undisturbed.The mobility of minerals deduced in this study shows that of all the mineral carbonates (cerussite (PbCO3),calcite (CaCO3), dolomite (CaMg(CO3)2), Pb which is predominantly formed in cerussite and has a lowsolubility which is supported by neutral to alkaline pH, disperses vertically farthest as seen at profile A depth 57-63cm than the other carbonate minerals at all other profiles.The DTPA extraction of heavy metals varies in abundance of Pb, low detections of K, Fe and Cu. The resultindicates a decrease in depth for Pb at depth profile A, while a change in proportion (increase and decrease)within other depth profiles for which no detection or range in quantification earlier persists in the PXRF result.These variations are as a result of slaked lime added to reagents to buffer the soil pH, complexation with solubleorganic matter followed by precipitation.The study shows that Pb and other heavy metals accumulate on surface soils, and with variations in abundancein topsoils of profiles B 0-22cm, C 0-20cm and profile A, percolated to depth 63cm. The immobilization of Pbbeneath these depths is associated with the adsorption onto solid phases and precipitation processes on clay-richand organic-rich soils. Only a small percentage of the total Pb would be leached while other mobile elements K,Fe and Zn would be removed at neutral to slightly alkaline soil pH through precipitation. Profiles D, E, F and G,had no visible evidence of tailings input, which is synonymous to below detection limits and low detection limitsof the XRD and PXRF spectrometer. Hence, surface runoff, which can transport soil particles containingcontaminating materials, aids lateral migration of heavy metals across the meadow. Subsequently, withconditions of the soil pH being neutral to slightly alkaline, soil particles adsorbs heavy metals while the moremobile elements precipitate within the soil.6.0 ConclusionAlthough the site is already contaminated with toxic metals, it is nonetheless imperative to forestall furthercontaminations of soil horizons, given that there have been varying increases in contaminations investigated. It isvery important to prevent further erosion and re-deposition of the tailings materials at the AMS from dispersinginto the field and surrounding areas. More so, the site should restrict the use of motorbikes at areas where thespoil heaps are eroding rather a separate area should be developed for the motorbike activities. The tailingmaterials should be prevented with appropriate soil plants as well as flow drainage system to cap the surfacewash into a separate site which can be used for further studies. Educating the public on the awareness of healthrisks involved in heavy metal consumption is very important within the mine site and at global level.ReferencesAdriano, D. C. (2001). Trace Elements in Terrestrial Environments: Biogeochemistry, Bioavailability and Risksof Metals (2nd edition) , 866.Alloway (ed), B. J. (1990). Heavy metals in soils. Glasgow: Blackie.Alloway, B. J. (1995). The origins of heavy metals in soils. In B. J. Alloway, Heavy Metals in Soils (p. 368).New York: Blackie Academic and Professional Publication.Berg, M., Tran, H. C., Nguyen, T. C., Phem, H. V., Schertenleib, R., and Giger, W. (2001). Arseniccontamination of groundwater and drinking water in Vietnam: a human threat. Environmental Science andTechnology, 35 , 2621-2626
  5. 5. Journal of Natural Sciences Research www.iiste.orgISSN 2224-3186 (Paper) ISSN 2225-0921 (Online)Vol.3, No.5, 201349Chambers, J. C., and Sidler, R. C. (1991). Fate of heavy metals in abandoned Pb-Zn tailings pond:1. Vegetation.J of Environmental Quality, 745-751.Gee, C., Ramsey, M. H., and Thorton, I. (2001). Buffering from secondary minerals as a migration limitingfactor in lead polluted soils at historical smelting sites. Applied Geochemistry, volume:16, 1193-1199.Johnson, M. S., and Eaton, J. W. (1980). Environmental Contamination through residual trace metal dispersalfrom derelict Pb-Zn mine. J. Environmental Quality. Volume 9, 175-179.Hong, P. K., Lia, C., Banerjib, S. K., and Wang, Y. (2002). Feasibility of metal recovery from soil using DTPAand its biostability. Journal of Hazardous Materials Volume 94, Issue 3, 253-272.Jenkins, R. (1999). X-Ray Analysis. Encyclopedia of Physical Science and Technology. Volume 3, 603-604.Johnson, R. H., Blowes, D. W., Robertson, W. D., & Jambor, J. L. (2000). The hydrogrochemistry of the nickelrim mine tailings impoundment, Sudbury, Ontario. J. Contam. Hydrol. Vol.41, 49-80.Jung, M. C. (2001). Heavy metal contamination of soils and waters in and around the Imcheon Au-Ag mine,Korea. Applied Geochemistry. Vol 16, 1369-1375.Kambata-Pendias, A., and Pendias, H. (1984). Trace elements in soils and plants. Florida: CRC Press.Kim, M. J., Ahn, K. H., and Jung, Y. (2002). Distribution of inorganic arsenic species in mine tailings ofabandoned mines from korea. Chemosphere. Vol 49, 307-312.Lindsay, W. L., and Norvell, W. A. (1978). Development of a DTPA test for zin, iron, manganese, and copper.Soil Science Society of America Journal, Volume: 42 Issue: 3, 421.Levy, D. B., Barbarick, K. A., Siemer, E. G., & Sommers, L. E. (1992). Distribution and partioning of tracemetals in contaminated soils near Leadville, Colorado. J. Environ. Quality. Vol.21, 185-195.Martin, R. C. (1998, August 25). Department of the Environment for Northern Ireland. Retrieved July 16, 2011,from Department of Environment Northern Ireland.: http://www.doeni.gov.uk/niea/whitespots_assi_citation.pdfMcGregor, R. G., Blowes, D. W., Jambor, J. L., and Robertson, W. D. (1998). Mobilization and attenuation ofheavy metals within a nickel mine tailings impoundment near Sudbury, Ontario, Canada. Environ. Geol. Vol. 36,305-319.Merrington, G. and Alloway, B. J. (1994). The transfer and fate of Cd, Cu, Pb and Zn from two historicmetalliferous mine sites in the UK. Applied Geochemistry. Vol 9, 677-687.Moles, N. R., Smyth, D., Maher, C. E., Beattie, E. H., & Kelly, M. (2004). Dispersion of cerussite-rich tailingsand plant uptake of heavy metals at historical mines. Transactions of the Institution of Mining and Metallurgy,part B. Applied Earth Science. Vol113, B21-B30.Navarro, M. C. (2004). Movilidad y biodisponibilidad de metales pesados en el emplazamiento minero CabezoRajao (Murcia). Ph.D. Thesis. Murcia: University of Murcia.Nawaz, R., and Moles, N. R. (2006, July 12). National Museums Northern Ireland. Retrieved July 16, 2011,from Geological Site in Northern Ireland: http://www.habitas.org.uk/escr/site.asp?item=529Ramsey, M. H., and Boon, K. A. (2011). Can in situ geochemical measurements be more fit-for-purpose thanthose made ex situ? Applied Geochemistry, 1-5Razo, I., Carrizales, L., Castro, J., Diaz Barriga, F., and Monroy, M. (2004). Arsenic and heavy metal pollutionof soil, water and sediments in a semi-arid climate mining area in Mexico. Water Air Soil Pollut., 129-152.Sidle, R. C., Chambers, C. J., and Amacher, M. C. (1991). Fate of heavy metals in an abandoned PB-Zn tailingspond sediment. J of Environmental Quality, 752-758.Weltje, G. J., and Tjallingii, R. (2008). Calibration of XRF core scanners for quantitative geochemical logging ofsediment cores. Theory and application Earth and Planetary Science Letters. Volume 274, Issues 3-4 , 423-438.
  6. 6. Journal of Natural Sciences Research www.iiste.orgISSN 2224-3186 (Paper) ISSN 2225-0921 (Online)Vol.3, No.5, 201350Table 1: Soil moisture contents and Soil pH result values.Profile A B C D E F GMoisturecontent % 13 - 45 12 – 33 12 – 32 31 – 52 10 – 38 18 – 42 18 – 29Soil pH Neutral Neutral –slightlyalkalineNeutral Neutral –slightlyalkalineNeutral –slightlyalkalineNeutral –slightlyalkalineNeutral –slightlyacidicTable 2: Comparisons between the PXRF in-situ and ex-situ readingsProfilesK Ca Fe Cu Zn Pbinsitu ex situinsitu ex situ in situexsitu in situexsitu in situexsituinsitu ex situppm ppm ppm ppm ppm ppm ppm ppm ppm ppm ppm ppmB 10815 11319 56751 51338 586 831 586 831 2049 3072 68093 107046D 9467 9060 6145 6799 28398 35489 72 135 158 286 2755 3802E 11166 9354 7048 11664 29153 38624 121 176 302 471 3038 4899F 7376 9318 7538 11146 22607 35371 202 320 117 194 2207 3737G 11562 13526 1857 3435 36067 48051 109 142 39 42 590 584Table 3: Metal concentration in soil samples after DTPA extractionmg/lProfile depth Pb K Fe CuA 50-57cm 86 14 0 14A 57-63cm 62 10 1 5A 63-68cm 35 7 8 4B 16-22cm 125 14 0 13B 28-36cm 143 12 4 5C 0-9cm 139 31 6 4C 9-17cm 134 17 0 11C 17-20cm 180 17 2 3C 20-27cm 131 6 8 4E 9-19cm 106 12 16 3E 19-29cm 67 7 19 4
  7. 7. Journal of Natural Sciences Research www.iiste.orgISSN 2224-3186 (Paper) ISSN 2225-0921 (Online)Vol.3, No.5, 201351Figure 1: In situ measurements for Pb, Zn, K, Ca, Fe and Cu in the vertical depth profile B.Figure 2: In situ measurements for Pb, Zn, K, Ca, Fe and Cu in the vertical depth profile D.UNITSX-axis ProfileY-axis ppmUNITSX-axis ProfileY-axis ppm
  8. 8. Journal of Natural Sciences Research www.iiste.orgISSN 2224-3186 (Paper) ISSN 2225-0921 (Online)Vol.3, No.5, 201352Figure 3: Ex-situ measurement of Ca, Fe and Pb using the PXRF spectrometerFigure 4: Ex-situ measurement of K, Cu and Zn using the PXRF spectrometerUNITSX-axis ProfileY-axis ppmUNITSX-axis ProfileY-axis ppm
  9. 9. Journal of Natural Sciences Research www.iiste.orgISSN 2224-3186 (Paper) ISSN 2225-0921 (Online)Vol.3, No.5, 201353Figure 5: Semi-quantitative output of quartz, cerussite and calcite minerals analysed.Figure 6: Semi-quantitative output of dolomite, clinochlore and plagoiclase minerals analysed.UNITSX-axis ProfileY-axis cmUNITSX-axis ProfileY-axis cm
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