Speciation of heavy metals in sediments from Baihua Lake and Aha Lake

ASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERINGAsia-Pac. J. Chem. Eng. 2009; 4: 635–642Published online 25 May 2009 in Wiley InterScience(www.interscience.wiley.com) DOI:10.1002/apj.307

Special Theme Research Article

Speciation of heavy metals in sediments from Baihua Lakeand Aha Lake

Xian-fei Huang, Ji-wei HU,* Jia-jun Deng, Cun-xiong Li and Fan-xin Qin

Guizhou Provincial Key Laboratory for Information System of Mountainous Areas and Protection of Ecological Environment, Guizhou NormalUniversity, Guiyang, 550001, China

Received 20 August 2008; Revised 3 February 2009; Accepted 22 February 2009

ABSTRACT: Baihua Lake and Aha Lake are both drinking-water sources for Guiyang City, the capital of GuizhouProvince in southwestern China. In the present research, chemical speciation of chromium (Cr), copper (Cu) and zinc(Zn) in the sediments from these two lakes was studied based on the sequential extraction procedure developed byTessier et al ., and organic matter (OM) was determined by ignition method. The results obtained are as follows:[1] Theorganic matter amounts in sediments from Baihua Lake and Aha Lake ranged from 11.62 to 18.02% and 8.48 to13.90%, respectively;[2] Cr and Zn were mainly distributed in residual phase, while Cu mainly existed in oxidizableand residual phases;[3] Levels of Cu distributed in oxidizable phase in sediments from Baihua Lake were higher thanthose from Aha Lake;[4] Mobility, bioavailability, and toxicity of Cu were low in comparison with Zn and Cr, becauseCu was mainly distributed in oxidizable and residual phases in which heavy metals mobility was lower than in the otherphases. The Pearson’s correlation coefficient between organic matter and Cr in oxidizable phase of the 20 sedimentsamples collected from the two lakes was up to 0.604 (p < 0.01). 2009 Curtin University of Technology and JohnWiley & Sons, Ltd.

KEYWORDS: Baihua Lake and Aha Lake; sediments; sequential extraction procedure; speciation of heavy metals

INTRODUCTION

There are various media that were available for inves-tigation of contaminants in aquatic ecosystems, suchas water, biota, suspended material, and sediments.[1]

Sediments have attracted a significant attention mainlybecause they have always been considered as asink and reservoir for a variety of environmentalcontaminants,[2,3] and also usually provide a record ofcatchments input into aquatic ecosystems.[4] In addition,it has been recognized that aquatic sediments absorbpersistent and toxic chemicals to levels many timeshigher than the water column concentration.[5] Whencircumstances of sediments are changed, these contam-inants would be released into the water column.

Heavy metals have been known to cause numerousadverse effects to humans and ecological systems, andpollution of aquatic systems with heavy metals hasaroused a huge public concern. Heavy metals may beintroduced into aquatic systems through many ways,such as industrial and municipal wastes, atmospheric

*Correspondence to: Ji-wei HU, Guizhou Provincial Key Laboratoryfor Information System of Mountainous Areas and Protection ofEcological Environment, Guizhou Normal University, Guiyang,550001, China. E-mail: [email protected]

emissions, metal corrosion products, and leached agri-cultural chemicals. To study heavy metals pollution,the total concentration of a heavy metal may be usefulas a comprehensive index;[6] nevertheless, it providesinadequate information about bioavailability and toxic-ity since mobility, bioavailability, and toxicity of heavymetals have close correlations with their speciation.[7]

Therefore, some researchers have suggested that totalcontents of heavy metal are not the best indicatorsof their bioavailability and toxicity.[8–11] In order toaddress this issue, sequential extraction (or fractiona-tion) procedures have been developed predominantlyto determine the amounts and proportions of metalspresent in different forms in sediment samples.[12,13]

Baihua Lake and Aha Lake, located on the Yun-gui Plateau in southwestern China, are two of thefive drinking-water sources for approximately threemillion population of Guiyang City, the capital ofGuizhou Province. They are both multi-functional watersystems not only for drinking-water provision, butfor flood control, shipping, and fishery as well. Bai-hua Lake (E 106◦27′ –106◦34′, N 26◦35′ –26◦ 42′) islocated in Qingzhen County and is only 16 km westof Guiyang City. It is a man-made lake built in the1960s when the second cascade hydropower stationwas established on Maotiao River, a major tributary ofWujiang River. The lake covers an area of 14.5 km2 and

2009 Curtin University of Technology and John Wiley & Sons, Ltd.

636 X. HUANG ET AL. Asia-Pacific Journal of Chemical Engineering

holds 191 million m3 of water. There are seven head-streams flowing into the lake, which are Dongmenqiao,Changchong, Maicheng, Maixi, Dayuanba, Shangmaixi,and Nanmen Streams. Aha Lake (E 106◦37′ –106◦40′,N 26◦30′ –26◦ 34′), built in 1950s, is located only 8 kmsouthwest of Guiyang City. The lake covers an area of3.4 km2 and holds 86.6 million m3 of water. Aha Lakeis situated on a tributary of River Nanming and fiveheadstreams converge here, which are Youyu, Baiyan,Sha, Lanni, and Caichong streams. In recent decades,with the development of various industries, urbaniza-tion, and agriculture in surrounding areas, the two lakeshave been polluted with various pollutants, e.g. heavymetals. Baihua Lake is surrounded by rapidly expandedtowns like Qingzhen City and high-pollution industrysuch as metal, chemical, and power plants, whereas AhaLake is especially close to hundreds of deserted smallcoal mines. These should significantly add to heavymetals and other contaminants loading in the two lakes.

Heavy metals pollution in the two lakes has stirredup strong concerns among researchers and several stud-ies have already been carried out. Hou et al . reportedthe different species of mercury in the overlaying waterof Baihua Lake.[14] In their study, mercury was clas-sified as reactive, dissolved, and particulate mercury.Huang et al . investigated the mercury pollution in sed-iments from Baihua Lake, indicating that the loadingof the element was still high. The mercury pollution inBaihua Lake has been well known among local commu-nities and believed to be caused by the past dischargesfrom a nearby organic chemical company which usedto produce acetaldehyde by employing the mercury-containing catalysts.[15] Bai et al . studied the concen-tration and distribution of different mercury species inthe water columns and sediment pore-water of AhaLake.[16] Hitherto, no data or information concerningspeciation of chromium (Cr), copper (Cu), and zinc(Zn) in sediments from Baihua Lake or Aha Lake werereported. The main objectives of the present researchwere to study the speciation of three heavy metals(Cr, Cu, and Zn) in sediments from Baihua Lake andAha Lake based on the sequential extraction proceduredeveloped by Tessier et al ., and to clarify the distribu-tion characteristics of these metals in different chem-ical phases. In addition, organic matters (OM) whichcontains numerous functional groups for the complexa-tion of trace metals was also investigated in sedimentssince it plays an extremely important role in partitioningbehavior of heavy metals.[17]

EXPERIMENTAL

Materials and methods

The sediment samples used in this study were collectedduring November 2007 in Baihua Lake and Aha Lake

Figure 1. Distribution of sampling sites in BaihuaLake. This figure is available in colour online atwww.apjChemEng.com.

Figure 2. Distribution of sampling sites in AhaLake. This figure is available in colour online atwww.apjChemEng.com.

(Figures 1 and 2). Superficial sediments were taken witha grab-sampler at 20 locations which were selectedbased on the size, shape, and water-flowing directionof the two lakes. In Baihua Lake, sediment sampleswere collected from locations of Dachong, Yueliang-wan, Meituwan, Pingpu, Laojiutu, Tieshuizhan, Long-tan, Yapengzhai, Jiangjiapu, and Guanyinshanzhuang.In Aha Lake, sediment samples were collected fromlocations of Caijiaguan, Daba, Dababian, Huachong,Zhufangba, Kailongzhai, Zhufangbabian, Lusidayan,Dahuangpo, and Mawozhai. Samples were put in glass

2009 Curtin University of Technology and John Wiley & Sons, Ltd. Asia-Pac. J. Chem. Eng. 2009; 4: 635–642DOI: 10.1002/apj

Asia-Pacific Journal of Chemical Engineering SPECIATION OF HEAVY METALS BAIHUA LAKE AND AHA LAKE 637

bottles (1000 cm3 volume) that were pre-cleaned with5% HCl (v/v) and 5% HNO3 (v/v), and immediatelytransported to the laboratory. In our laboratory, thesediments were centrifuged and the supernatants werediscarded. The resulting sediment materials were driedat room temperatures and then ground into powder foranalysis. At the same time, 3.0000 g of each sedimentsample powder was dried at 105 ◦C for 24 h to deter-mine moisture.

Instruments and reagents

The following instruments were used in this research:[1]

inductively coupled plasma atomic emission spectrom-etry (ICP-AES, Optima 5300V) made by Perkin Ele-mer Corporation from USA;[2] water purification sys-tem (Nex Power 2000) by Human Corporation fromKorea;[3] immersion oscillator (SHZ-C) by ShanghaiYuejin Medical Instruments Company from China. Allreagents used in this study were made in China. Thehydrochloric acid (HCl), nitric acid (HNO3), and per-chloric acid (HClO4) were guaranteed reagents, and theother reagents were with analytical grade.

Analytical procedures

Analysis of total amount of heavy metals insediments from the two lakesTo analyze the total amount of heavy metals in sed-iment from the two lakes, 0.5000 g of each sedimentsample was weighed accurately in a 250-ml beakerand 20 ml of digesting mixture made up of con-centrated nitric acid and concentrated perchloric acid[nitric acid: perchloric acid = 4 : 1 (V/V)] was added.The beakers were placed on an adjustable electric heat-ing plate, and heated with low temperature for ca60 min; then the electric heating plate was adjusted tothe highest temperature and the heating was continueduntil a small amount of solution was left and the colorof sediment was changed to the white. The remainingsolution and sediment were transferred into a 50-ml vol-umetric flask and diluted to the full volume with 0.5%(V/V) nitric acid solution. The solutions prepared abovewere used to determine the total amount of Cr, Cu, andZn with ICP-AES.

Chemical fractionation of heavy metals insediments by sequential extraction procedureFirst step (Exchangeable fraction, F1): 1.0000 g of eachsediment sample was weighed accurately in 100-mlcentrifuge tube, and 15 ml of 1 mol/l MgC12 solutionwas added. Thereafter, the mixture was shaken onthe oscillator mentioned above at 30 rpm at roomtemperature for 2 h. The extract was separated from

the solid residue by centrifugation at 3000 × g for20 min. The supernatant was decanted and collected foranalysis. The residue fraction was washed by adding20 ml of deionized water, shaking for 15 min on theoscillator, and centrifuging for 20 min at 3000 × g . Thesupernatant was decanted and discarded, and the residuewas reserved for the analysis of next step. Second step(Bound to Carbonates fraction, F2): Fifteen millilitersof 1 mol/l NaOAc was added to the residue from thefirst step. The mixture was shaken on the oscillator at30 rpm at room temperature for 2 h. The extract wasseparated as performed in the first step, the residue waswashed as in the previous step, and the supernatant wasdecanted and discarded. Third Step (Reducible Fraction,F3): Twenty milliliters of 0.04 mol/l NH2OH · HCl in25% HOAc was added to the residue from the secondstep. The mixture was shaken on the oscillator at 30 rpmat 85 ± 2 ◦C for 3 h; then another 10 ml of NH2OH ·HCl was added and the resulting mixture was shakenfor another 2 h. The extract was separated as in the firststep, the residue was washed as in the previous step, andthe supernatant was decanted and discarded. Fourth step(Oxidizable fraction, F4): Three milliliters of 0.02 mol/lHNO3 and 5 ml of 30% H2O2 were added to the residuefrom the third step, and the pH value was adjusted to 2.0with HNO3. About 1 h later, The mixture was shakenon the oscillator at 30 rpm at 85 ± 2 ◦C for 2 h; thenan additional 3 ml of 30% H2O2 (the pH value wasadjusted to 2.0 with HNO3) was added and the mixturewas shaken on the oscillator at 30 rpm at 85 ± 2 ◦C for3 h. The extract was separated as in previous steps andthe residue was discarded. Residual fraction (F5) wasequal to the difference between the total content andthe sum of the former four fractions. At the same time,the blanks were measured in parallel for each set ofanalysis using the extraction reagents described above.

Analytical procedure of organic matter insedimentsOM was determined as a loss on ignition at 550 ◦C in12 h to obtain constant weight.

RESULTS AND DISCUSSION

Total concentrations of heavy metals insediments from the two lakes

The total concentrations of each heavy metal in the 20sediment samples are listed in Table 1. Concentrationsof each heavy metal (C) are calculated with the follow-ing equation:

C = (Cs × V )

M × (1 − Pm)

where CS stands for the measured concentration ofeach heavy metal in solution prepared from a sediment



sample for analytical procedure; V is the volume of thesolution prepared from the sediment sample; M standsfor the sample weight; Pm is the percentage of moisturein the sample. As shown in Table 1, it is obvious thatthe concentrations of Zn in sediment samples from AhaLake were higher than those from Baihua Lake, andconcentrations of Cr and Cu did not show significantdifference between the two lakes.

In sediment samples from Baihua Lake, the con-centrations of Cr, Cu, and Zn ranged from 27.2to 78.7 mg/kg, 45.9 to 116.0 mg/kg, and 78.6 to449.6 mg/kg, and the mean values were 59.7, 74.9,and 283.6 mg/kg, respectively. All of the three elementswere at low concentrations at sampling site Meituwanand high concentrations at sampling site Jiangjiapu.Because the sampling site Meituwan is located in themiddle of the lake, contaminants from headstreamscould not reach there easily but were mostly depositedin the upper part of the lake, whereas there was a head-stream named Lannigou flowing into the Baihua Lakeat the sampling site Jiangjiapu; this could be why all ofthe three elements presented higher concentrations herethan at site Meituwan.

In the sediment samples from Aha Lake, the con-centrations of Cr, Cu, and Zn ranged from 40.6to 100.4 mg/kg, 34.0 to 96.2 mg/kg, and 204.5 to689.3 mg/kg, and the mean values were 56.9, 65.4, and386.6 mg/kg, respectively. At the sampling site Daba,Cr was present at a high concentration of 100.4 mg/kg,which was nearly one time higher than at other sampling

Table 1. Amount of Cr (mg/kg), Cu (mg/kg), Zn (mg/kg),and OM (%) in sediments from Baihua Lake and AhaLake.(dry weight, dw).

Sampling sites Cr Cu Zn OM

Baihua LakeDachong 67.0 74.7 325.0 11.91Yueliangwan 59.3 71.1 324.9 13.21Meituwan 30.8 47.8 214.4 14.27Pingpu 27.2 83.1 262.4 13.18Laojiutu 72.2 95.7 331.5 11.71Tieshuizhan 73.3 74.9 219.4 14.70Longtan 61.6 68.3 251.5 17.38Yapengzhai 60.4 45.9 178.6 18.02Jiangjiapu 78.7 72.2 449.6 12.08Guanyinshanzhuang 67.0 116.0 278.5 11.62Aha LakeCaijiaguan 42.9 34.0 234.4 10.62Daba 100.4 92.3 204.5 12.55Dababian 54.3 39.5 223.3 12.79Huachong 51.4 58.1 285.8 11.81Zhufangba 58.9 64.9 581.9 10.95Kailongzhai 59.1 96.2 689.3 13.90Zhufangbabian 40.6 92.2 507.7 13.50Lusidayan 50.6 53.8 457.3 12.54Dahuangpo 46.7 87.6 455.9 10.88Mawozhai 63.6 34.9 226.0 10.62

sites, and that could be caused by serious pollution fromuntreated urban sewage discharged from nearby townsand villages. Cu and Zn presented similar distributioncharacteristics which indicated that the concentrationsin the southern part of the Aha Lake were higher thanthose in the northern part, except for the sampling siteMawozhai. To our knowledge, there were a large num-ber of small coal mines distributed around the south-ern part of the lake, from which wastewater dischargesshould be partly responsible for this pollution.

Distributing characteristics of organic matterin sediments

The contents of OM in sediments from Baihua Lakewere high in comparison with those from Aha Lake(Table 1). In Baihua Lake, the amounts of OM rangedfrom 11.62 to 18.02%, and the average value was13.81%. The largest value turned up at the samplingsite of Yapengzhai. Following Yapengzhai, the value forthe sampling site Longtan was up to 17.38%. Amountsof OM in these two sampling sites were much higherthan those in the other sampling sites. At the samplingsite Laojiutu, the OM had the lowest content. Proba-bly, pollution from the nonpoint sources (agriculturalcultivation and fertilization) around Yapengzhai andLongtan sampling sites were more severe than aroundthe other sampling sites. Around the sampling sites ofYapengzhai and Longtan was mainly farming land whilethe other sampling sites are surrounded by forest andwasteland.surround. In Aha Lake, amounts of OM inthe sediments ranged from 8.48 to 13.90% and the meanvalue was 11.80% lower than that in Baihua Lake.

Speciation of heavy metals in sediments

As shown in Tables 2–4 and Figures 3–5, in somesamples, heavy metal concentrations were not detected(ND) in certain phases, mainly in the exchangeable onefor Cr; exchangeable, carbonate, and reducible ones forCu; and mainly in the exchangeable and reducible onesfor Zn.

It was evident that the residual phase was the mostdominant sink for Cr (57.57–87.46%) in sedimentsfrom both lakes. Carbonate, reducible, and oxidizablephases were also important phases for this element,and they, respectively, accounted for 3.93–13.16%,3.82–14.34% and 4.33–30.76% of its total amountin the 20 sediment samples. Although there were nodetectable concentrations of Cr in exchangeable phaseof all samples, Cr bound to carbonate (Cr – F2) anddistributed in reducible phase (Cr – F3) presented highpercentages at sampling sites Meituwan and Pingpuin Baihua Lake and at sampling sites Zhufangbabian,Lusidayan, and Dahuangpo in Aha Lake. The high-est percentage of Cr bound to iron and manganese



Table 2. Speciation of Cr in sediments from Baihua Lake and Aha Lake (dry weight, dw).

Exchangeable Carbonate Reducible Oxidizable Residual

Sampling sites mg/kg % mg/kg % mg/kg % mg/kg % mg/kg %

Baihua LakeDachong NDa – 3.94 5.88 4.20 6.27 5.65 8.44 53.16 79.40Yueliangwan ND – 3.99 6.73 4.01 6.76 4.86 8.20 46.44 78.31Meituwan ND – 4.05 13.16 3.99 12.97 4.38 14.23 18.35 59.64Pingpu ND – 3.43 12.65 3.89 14.34 3.88 14.31 15.92 58.70Laojiutu ND – 4.02 5.56 3.83 5.30 3.91 5.41 60.49 83.72Tieshuizhan ND – 4.49 6.13 4.56 6.23 11.62 15.86 52.58 71.78Longtan ND – 3.55 5.76 3.64 5.91 18.95 30.76 35.47 57.57Yapengzhai ND – 3.87 6.40 3.52 5.82 4.65 7.69 48.41 80.08Jiangjiapu ND – 5.86 7.45 6.33 8.04 5.13 6.52 61.37 77.99Guanyinshanzhuang ND – 3.26 4.87 3.73 5.57 2.90 4.33 57.06 85.23Aha LakeCaijiaguan ND – 3.63 8.46 3.76 8.76 2.41 5.62 33.11 77.16Daba ND – 3.95 3.93 3.84 3.82 4.80 4.78 87.81 87.46Dababian ND – 3.96 7.29 3.76 6.92 3.82 7.03 42.79 78.76Huachong ND – 3.64 7.08 3.95 7.69 4.68 9.11 39.11 76.12Zhufangba ND – 3.80 6.45 4.16 7.06 4.83 8.20 46.10 78.28Kailongzhai ND – 4.27 7.23 4.58 7.75 5.90 9.99 44.33 75.03Zhufangbabian ND – 4.15 10.23 4.35 10.73 5.13 12.65 26.92 66.39Lusidayan ND – 4.24 8.38 5.18 10.24 4.88 9.65 36.27 71.72Dahuangpo ND – 4.23 9.06 4.80 10.28 5.13 10.99 32.54 69.68Mawozhai ND – 3.92 6.17 3.84 6.04 3.23 5.08 52.58 82.71

a ND: Not detected

Table 3. Speciation of Zn in sediments from Baihua Lake and Aha Lake.



Baihua LakeDachong NDa – 25.0 7.69 0.6 0.18 51.9 15.96 247.6 76.16Yueliangwan ND – 49.4 15.22 2.4 0.74 36.7 11.31 236.0 72.73Meituwan ND – 28.0 13.06 1.1 0.51 35.6 16.60 149.7 69.82Pingpu ND – 15.2 5.79 0.2 0.08 27.7 10.56 219.3 83.57Laojiutu ND – 28.3 8.54 2.1 0.63 27.5 8.30 273.4 82.52Tieshuizhan ND – 10.2 4.65 ND – 38.7 17.65 170.4 77.70Longtan ND – 12.4 4.93 0.5 0.20 50.4 20.05 188.1 74.82Yapengzhai ND – 6.8 3.81 ND – 31.8 17.81 140.0 78.39Jiangjiapu ND – 9.7 2.16 1.3 0.29 56.3 12.53 382.2 85.03Guanyinshanzhuang ND – 8.1 2.91 1.3 0.47 33.4 11.99 235.8 84.64Aha LakeCaijiaguan ND – 7.8 3.33 ND – 11.0 4.69 215.7 91.98Daba ND – 8.2 4.02 ND – 27.8 13.61 168.2 82.37Dababian ND – 1.9 0.85 ND – 17.3 7.75 204.1 91.40Huachong ND – 7.3 2.55 ND – 22.0 7.70 256.5 89.75Zhufangba ND – 7.2 1.24 ND – 69.9 12.01 504.7 86.75Kailongzhai ND – 20.8 3.02 ND – 76.8 11.15 591.4 85.83Zhufangbabian ND – 25.9 5.10 ND – 79.7 15.71 401.8 79.19Lusidayan 0.7 0.15 18.7 4.09 2.1 0.46 80.2 17.54 355.6 77.76Dahuangpo ND – 28.0 6.14 2.0 0.44 77.9 17.09 348.0 76.33Mawozhai ND – 13.5 5.97 ND – 35.3 15.62 177.2 78.41

a ND: Not detected



Table 4. Speciation of Cu in sediments from Baihua Lake and Aha Lake.



Baihua LakeDachong NDa – 1.00 1.34 ND – 31.83 42.59 41.91 56.07Yueliangwan ND – 0.80 1.13 ND – 29.17 41.04 41.10 57.83Meituwan ND – ND – ND – 28.46 59.60 19.29 40.40Pingpu ND – ND – ND – 28.34 34.10 54.78 65.90Laojiutu ND – ND – ND – 35.53 37.13 60.17 62.87Tieshuizhan ND – ND – ND – 43.78 58.43 31.15 41.57Longtan ND – ND – ND – 52.19 76.39 16.13 23.61Yapengzhai ND – 0.52 1.13 ND – 15.49 33.73 29.91 65.14Jiangjiapu ND – ND – ND – 62.83 87.01 9.38 12.99Guanyinshanzhuang ND – ND – ND – 59.53 51.32 56.47 48.68Aha LakeCaijiaguan ND – 3.05 8.97 ND – 6.09 17.91 24.86 73.12Daba ND – ND – ND – 57.94 62.79 34.33 37.21Dababian ND – 1.36 3.44 ND – 10.47 26.49 27.69 70.07Huachong ND – ND – ND – 15.08 25.96 43.01 74.04Zhufangba ND – ND – ND – 13.86 21.35 51.05 78.65Kailongzhai ND – ND – ND – 14.82 15.40 81.41 84.60Zhufangbabian 0.51 0.55 1.40 1.52 ND – 24.51 26.60 65.74 71.33Lusidayan 0.53 0.99 3.62 6.73 ND – 25.01 46.50 24.63 45.79Dahuangpo 0.52 0.59 2.00 2.28 ND – 41.66 47.56 43.42 49.57Mawozhai ND – ND – ND – 14.10 40.42 20.78 59.58

a ND: Not detected

Figure 3. Speciation of Cr in sediments from Baihua Lakeand Aha Lake.

(Cr – F4) was characterized at sampling site Longtanin Baihua Lake, and that was characterized at samplingsite Zhufangbabian in Aha Lake. The residual fraction(Cr – F5) showed lower percentages of Cr at sam-pling sites Meituwan, Pingpu, and Longtan in BaihuaLake, and at sampling sites Zhufangbabian, Lusidayan,

Figure 4. Specification of Cu in sediments from Baihua Lakeand Aha Lake.

and Dahuangpo in Aha Lake. Similarly, there was nodetectable Zn in exchangeable phase in the 20 sedimentsexcept the one collected from the sampling site Lusi-dayan in Aha Lake. The residual phase was again a sig-nificant sink for Zn in both the lakes (69.82–91.98%),and the highest percentage of Zn in residual phase



Figure 5. Specification of Zn in sediments from Baihua Lakeand Aha Lake.

turned up at sampling site Jiangjiapu in Baihua Lakeand at sampling site Caijiaguan in Aha Lake, respec-tively. In carbonate and oxidizable phases, Zn presenteda minor distribution, accounting for 0.85–15.22% and7.70–20.05% of the total amount in all samples. In con-trast to Cr and Zn, Cu presented its own distributioncharacteristics among all of the geochemical phases.Unlike Cr and Zn, the residual phase for Cu was not theonly single important phase. In oxidizable and residualphases, percentage of Cu ranged from 15.40 to 87.01%and 12.99 to 84.60% of the total amount, respectively.In the other geochemical phases, Cu exhibited a ratherlimited distribution (ND – 8.97%). Based on the theoryof the sequential extraction procedure applied in thisstudy, the heavy metals distributed in the former geo-logical phases have a higher chance to be transferredinto the overlying water than in the latter geologicalphases. Therefore, special attention should be paid toCr and Zn among the three metals under investigation.

It is known that metals in the oxidizable phase maybe bound to active sites of organic molecules or precip-itated as sulfides. With the depletion of the dissolvedoxygen content in the sedimentary environment as aresult of microbiological activity, sulfate is the majorelectron acceptor driving OM oxidation in anaerobicsediments. The generated sulfide [that may be repre-sented by acid volatile sulfide (AVS) in the processof OM oxidation] is an important ligand, which canform stable metal sulfide precipitates in sediments, andthereby governs the behavior of divalent metals.[18–20]

Therefore, in deep-water lake or lake with eutrophica-tion, some heavy metals have the tendency to accumu-late in oxidizable and residual phases. In the present

Table 5. Correlations between OM and each heavymetal distributed in the oxidizable phase of sedimentsfrom Baihua Lake and Aha Lake.

OM Cr Cu Zn

OM Pearson correlation 1Cr Pearson correlation 0.604∗ 1Cu Pearson correlation 0.097 0.367 1Zn Pearson correlation 0.004 0.194 0.099 1

∗ p < 0.01 level, two-tailed;

research, concentrations of OM in sediments from Bai-hua Lake were much higher than those from Aha Lake.This is probably one of the reasons why Cu showedmuch higher importance to oxidizable phase of sed-iments from Baihua Lake than from Aha Lake. Thecorrelations between OM and each heavy metal dis-tributed in oxidizable phase were analyzed and tabulatedfor the 20 sediment samples collected from Baihua Lakeand Aha Lake (Table 5). It is noted that the Pearson’scorrelation coefficient between OM contents and Crconcentrations in oxidizable phase of the 20 sediments(fraction χ ) was 0.604 (p < 0.01), although there wereno significant associations between OM contents andthe levels of the other two elements.

On comparison of Baihua Lake and Aha lake withPoyang Lake in Jiangxi Province and Taihu Lake inJiangsu Province, some common characteristics anddifferences were evidenced.[21,22] For all the four lakes,residual phase was only one predominating phase forCr and Zn, whereas both the oxidizable and the residualwere important phases for Cu. The differences for thoselakes lie in the exchangeable phase. In Poyang Lakeand Taihu Lake, Cr, Cu, and Zn were all detectable inthe phase. In the present study, however, no detectableconcentrations were found in the exchangeable phasefor Baihua Lake and Aha Lake. These two lakes areboth deep-water lakes (the depth of water was upto 50 m at some sites), whereas Poyang Lake andTaihu Lake are shallow ones. In addition, Baihua Lakeand Aha Lake are both carbonate karst reservoirs.Probably, such distinctive characteristics have causedthe differences.

CONCLUSIONS

The results obtained from the present study haveafforded an important bearing on metal bioavailabilityand toxicity to aquatic biota, particularly to thoseorganisms living in the sediment environment. Toconclude, Cu was mainly bound to the oxidizable andresidual phases in the sediments from the two lakes, andshowed a rather limited distribution in exchangeable,carbonate, and reducible phases; therefore, Cu posed amuch lower risk to the water body in normal conditions



because of its low mobility in the sediment environmentcoming from diagenetic processes. Zn and Cr wouldbe the critical elements in terms of hazard to thelakes created by the heavy metals under investigation,because they are more easily translocated and absorbedby benthos owing to their distribution in carbonate orreducible phase

Acknowledgements

This work was supported by the Government ofGuizhou Province (Projects No. [2007]400126 and No.TZJF-2006-27) and the Chinese Ministry of Education(Project No. 206135).

REFERENCES

[1] J. Kruopiene. Polish J. Environ. Stud., 2007; 16, 715–722.[2] N. Milenkovic, M. Damjanovic, M. Ristic. Polish J. Environ.

Stud., 2005; 14, 781–787.[3] B. Kronvang, A. Laubel, S.E. Larsen, N. Friberg. Hydrobiolo-

gia, 2003; 494, 93–101.[4] J. Mwamburi. Lakes & Reservoirs: Research & Management,

2003; 8, 5–13.[5] S.T. Casper, A. Mehra, M.E. Farago, R. Gill. Environ.

Geochem. Health, 2004; 26, 59–67.

[6] O.S. Adefemi, O. Olaofe, S.S. Asaolu. Pak. J. Nutr., 2007; 6,705–707.

[7] R.Y. Li, H. Yang, Z.G. Zhao, J.J. Lu, X.H. Xiao, F. Jing.Pedosphere, 2007; 17, 265–272.

[8] M. Jakubus, J. Czekaµa. Polish J. Environ. Stud., 2001; 10,245–250.

[9] H.M. David, T. Ryan, L. Donald. Elements, 2005; 1, 21–216.[10] Z.S. Ahnstrom, D.R. Parker. Soil Sci. Soc. Am. J., 1999; 63,

1650–1658.[11] J. Shiowatana, R.G. McLaren, N. Chanmekha, A. Samphao.

J. Environ. Qual., 2001; 30, 1940–1949.[12] A. Tessier, P.G. Campbell, M. Bisson. Anal. Chem., 1979; 51,

844–847.[13] R.G. McLaren, L.M. Clucas. J. Environ. Qual., 2001; 30,

1968–1975.[14] Y.M. Hou, X.B. Feng, G.L. Qiu, H.Y. Yan. J. Lake Sci. (in

Chinese), 2004; 16, 125–132.[15] X.F. Huang, J.W. Hu, F.X. Qin, W.J. Fu, M.S. Zhang,

Q.C. Peng, G.Q. Lian. Environ. Pollut. Control (Web Edition)(in Chinese), 2007; 5, 1–5.

[16] W.Y. Bai, X.B. Feng, L. Sun, T.R. He, X.W. Fu, H.M. Jang.Acta Scientiae Circumstantiae (in Chinese), 2006; 26, 91–98.

[17] A. Kaschl, V. Romheld, Y. Chen. J. Environ. Qual., 2002; 31,1885–1892.

[18] H.M. Fernandes. Environ. Pollut., 1997; 97, 317–325.[19] B.G. Lee, S.B. Griscom, J.S. Lee, H.J. Choi, C.H. Koh,

S.N. Luoma. Science, 2000; 287, 282–284.[20] S.E.J. Buykx, M.A.G.T. van den Hoop, J.P.G. Loch.

J. Environ. Qual., 2002; 31, 573–580.[21] X. Gong, S.J. Liu, W.P. Cao, M.B. Luo. Acta Agric. Univ.

Jiangxiensis (in Chinese), 2006; 28, 620–624.[22] X.Y. Yuan, A.H. Wang, N.Z. Xu. Geochemcial, 2004; 33,

611–618.


Documents

Speciation of heavy metals in sediments from Baihua Lake and Aha Lake