Assessment of drain water receiving effluent from tanneries and its impact on soil and plants with particular emphasis on bioaccumulation of heavy metals

In the present study, impact of tannery and other industrial effluents on the physico-chemical characteristics of loamy drain water and their consequent impact on soil and plants irrigated with effluent have been studied. The study reveals most of the parameter pH, BOD5 and COD at sampling station I was higher than station II. Waste water quality at both Stations I and II exceeded prescribed limits (BIS) for safe disposal of effluents into the surface water Samples of soil and vegetables from the land irrigated with loamy drain water has been collected and analyzed for Cu, Zn, Ni, Cr Pb and Cd. The different metals showed different enrichment factor for loamy drain water irrigated soil and are as follows: Cd 30% (max), Pb 26%, Zn 18%, Cr 5%, Cu 5%, Ni 2% (min). For plant samples collected at polluted sites are Ni 46% spinach (whole plant) (max), Zn 42% spinach (whole plant), Cr 39% spinach (whole plant), Cu 33% spinach (whole plant), Pb 20% potato tuber, Cd 20% potato tuber (min). The levels of Zn 145, Cu 5.25, and Ni 39.25 microg/ g in spinach, Pb 29.25, Cr 38. 25 and Cd 3.2 microg/g in potato tuber grown on polluted soil irrigated with contaminated drain water were found more than the reference value, which may create chronic health hazard problem to human and cattle through food chain in long run. Accumulation of toxic heavy metals may be build up in the agriculturally productive land where it is treated with contaminated effluent enrich with metals in turn bio-concentrated in the edible fodder/plants.     

Uptake and accumulation of potentially toxic metals (Zn, Cu and Pb) in soils and plants of Durgapur industrial belt

Uptake and accumulation of metals in crops may cause possible health risks through food chain. A field survey was conducted to investigate the accumulation of potentially toxic metals contamination in soil and plants irrigated with complexed industrial effluents. Concentration of Zn, Cu and Pb was 205-255,101-130,118-177 microg g(-1) in rhizosphere soils and 116-223, 57-102 and 63-95 microg g(-1) d. wt. in root and 95-186, 44-75 and 27-58 microg g(-1) d. wt. in shoot, respectively. The trend in Cu and Pb was in the order: soil > root > shoot > seed while in Zn it was soil > root > seed > shoot. Roots accumulated a larger fraction of soil Cu (70%) > Zn (67%) > Pb (54%). Bioaccumulation coefficient of soil to root ranged from 51-98 for Zn, 54-85 for Cu and 43-63 for Pb.Analysis of variance showed marginal change in bioaccumulation coefficient, noticed between plants (p > 0.05) while it varied significantly (p < 0.01) between tissues and metals. It increased from root to seed/fruit (root > shoot > seed/fruit) while decreased between metals from Zn to Pb (Zn > Cu > Pb). Out of the three, two Cu and Pb accumulated to phyotoxic levels while Zn was within threshold limit of phytotoxicity.     

Combined effect of iron and zinc on micronutrient levels in wheat (Triticum aestivum L.)

A nutrient solution experiment was conducted to investigate the effect of Fe and Zn supply on Fe, Zn, Cu, and Mn concentrations in wheat plants. The experiment used a factorial combination of two Fe levels (0 and 5 mg l(-1)) and three Zn levels (0, 0.1 and 10 mg I(-1)). The supply of Fe (5 mg l(-1)) and Zn (0.1 mg l(-1)) increased plant dry weight and leaf chlorophyll content compared to the Fe or Zn deficient (0 mg 11) treatments. However, excess Zn supply (10 mg l(-1)) reduced plant dry weights and leaf chlorophyll content. Iron supply (5 mg l(-1)) reduced wheat Zn concentrations by 49%, Cu concentrations by 34%, and Mn by 56% respectively. Zinc supply (10 mg l(-1)) reduced wheat Fe concentrations by an average of 8%, but had no significant effect on Cu and Mn concentrations. Stepwise regression analyses indicated that Zn, Cu, and Mn concentrations were negatively correlated with root- and leaf-Fe concentrations, but positively correlated with stem-Fe concentrations. Leaf-Mn concentrations were negatively correlated with root-, stem- and leaf-Zn concentrations.     

Concentration of heavy metals in water and chub, Leuciscus cephalus (Linn.) from the river Yildiz, Turkey

The concentration of heavy metals (Cu, Fe and Zn) were determined by atomic absorption spectrophotometry in the river water and the edible muscle tissues of chub, Leuciscus cephalus, from river Yildiz, Turkey, and in the waste water The following results were found in the water of the river Yildiz: Cu 0.03-0.53, Fe 0.91-1.96 and Zn, 053-1.49 microgl(-1), in the waste water Cu 0.20-0.52, Fe 1.22-2.29 and Zn 0.92-1.46 microgl(-1) and in the edible muscle of chub: Cu 1.00-3.79, Fe 7.21-17.04 and Zn 4.12-18.33 microg g(-1) wet weight respectively. Among the heavy metals studied Pb, Cd, Co, Cr, Ni and Mn were not detected in the river water, waste water and chub samples. Heavy metal contents in these samples were evaluated and the highest concentrations of Cu, Fe and Zn were found in the muscle tissue. The levels of the heavy metals were detected in decreasing order as iron> zinc> copper. All the samples contained comparatively lower amounts of metals as suggested by international and national regulatory bodies. Thus, we recommend periodic monitoring of these metals in the fish consumed by local people.     

Evaluation of genotoxic potential of industrial waste contaminated soil extracts of Amritsar, India

The rapid increase in population together with unplanned disposal of effluents from various industries has resulted in accumulation of various heavy metals like As, Cr, Cu, Hg, Ni, Pb and Zn in soil ecosystem which ultimately causes DNA damage in living systems. Considering this, the present study was designed to evaluate the content of various heavy metals (Cu, Cr, Co, Hg, Mn, Ni, Zn) and genotoxicity/mutagenicity of soil samples collected from the outskirts of two industries viz. zinc coating industry (SI) and copper sulphate manufacturing industry (SII) employing Allium root anaphase aberration assay (A/RAAA) and Ames assay. The physicochemical parameters like bulk density, water holding capacity, moisture content, pH, nitrates, phosphates and potassium were also estimated. It was observed that SI sample contained Ni (6.86 mg g-1), Zn (6.53 mg g-1), Co (5.05 mg g-1) and Cr (4.49 mg g-1), while SII contained Cu (32.86 mg g-1), Ni (9.66 mg g-1), Co (6.85 mg g-1) and Zn (5.41 mg g-1). In A/RAA assay, the percentage of cells with anaphase aberrations ranged from 3.63 to 10.67 and 0.38 to 4.83% for samples SI and SII, respectively. In Ames test, sample SII was found to be lethal to Salmonella tester strains at all concentrations used, while sample SI was found to be mutagenic in TA100 strains of Salmonella typhimurium. Sample SII was found to be strongly acidic with pH 3.46. The present study focuses on the increasing heavy metal pollution in Amritsar city due to industrial discharges over lands and also infers that both bioassays Ames and A/RAAA can serve as first alert indication of pollution.     

Soil pollution by trace metals derived from animal feed and manure in the Bursa region of Turkey

The Bursa region of Turkey has important agricultural production areas. Animal producers use agricultural fields in this region for disposal of manure. Therefore, in this study the concentrations of the seven trace metals Zn, Mn, Cu, Ni, Cr, Pb, and Cd in 324 animal feed and manure samples from three dairy cattle, three laying hens farms, and three broiler farms have been determined. The average concentrations in dairy cattle manure were 130 (Zn), 150 (Mn), 4.2 (Cu), 6.8 (Ni), 44 (Cr), 0.8 (Pb), and 0.09 (Cd) mg kg^?1 dry weight; for laying hens manure 240 (Zn), 190 (Mn), 0.63 (Cu), 3.8 (Ni), 30 (Cr), 0.55 (Pb), and 0.12 (Cd) mg kg^?1 dry weight; and for broiler manure 240 (Zn), 280 (Mn), 1.4 (Cu), 3.8 (Ni), 35 (Cr), 3.4 (Pb), and 0.16 (Cd) mg kg^?1 dry weight. The calculated trace metal loading rate indicated that manure application might pose a potential risk to agricultural fields according to the current soil protection regulations of Turkey.     

Heavy metal contamination of soil,and bioaccumulation in vegetables irrigated with treated waste water in the tropical city of Varanasi,India

The present study was conducted to determine the heavy metal contamination in soil with accumulation in plants in waste water irrigated areas. Results revealed that waste water contained lower concentrations of Cr, Zn, Cu, and Pb except Cd (0.03) than the permissible limits prescribed by the World Health Organization. The maximum metal concentrations occurred in Brassica oleracea (Zn 63.80, Cu 12.25, Cr 10.65, Pb 3.63, and Cd 0.56 mg Kg^?1).The metal enrichment (EF of Cd 1.9, Cr2.9, Zn 4.8, Cu 6.5, and Pb 15.5) and degree of contamination (CF of Cd 2.9, Cr 2.0, Zn 2.3, Cu 2.7, and Pb 2.2) showed that accumulation of the five toxic metals increased during sewage irrigation as compared with the reference values, other Indian regions and globally. However, based on WHO standards for heavy metal contamination of soil and irrigation water, our data does not ensure safe levels for food.     

电镀污染区植物对复合重金属的富集、转移和对污染土壤的修复潜力

采用野外采样室内分析方法,对重庆市3个电镀厂污染区自然定居的23种优势植物和相应土壤中Cu、Zn、Cr和Ni 4种重金属含量进行测定,揭示了优势植物对复合污染重金属的富集和转移特征。结果表明,电镀污染区土壤中Cu、Zn、Cr和Ni平均含量分别为560.0、722.6、1 364.3和735.7 mg·kg-1,分别为GB 15618—1995《土壤环境质量标准》中三级标准限值的1.40、1.45、3.90和3.68倍。植物对重金属的吸收、富集和转移特性因植物种类、植株部位、污染地及重金属种类的不同而不同,污染地植物吸收的重金属富集滞留在根部较多,扁穗牛鞭草(Hemarthria compressa)和野薄荷(Mentha haplocalyx)表现出超富集Cr的潜力,其地上部分Cr平均含量分别为1 559.2和1 914.6 mg.kg-1,生物转运系数分别为1.29和1.58,生物富集系数分别为1.58和1.79,其他植物地上部分Cr含量超过正常植物百倍以上的有14种,平均富集量为376.4 mg·kg-1,变化范围为121.2～694.3 mg·kg-1,地上部分Ni含量超过正常植物百倍以上的有8种,平均富集量为344.1 mg·kg-1,变化范围为220.3～532.1 mg·kg-1。它们是修复电镀重金属Cr和Ni复合污染土壤的理想植物。     

电镀厂污染土壤重金属形态及淋洗去除效果

以某电镀厂污染场地重污染区域土壤为研究对象,对土壤中重金属全量和各形态含量进行分析,并研究筛选高效土壤淋洗剂,比较其淋洗去除效果。结果表明,该土壤以铬和镍污染最为严重,土壤铬和镍含量分别达1 564.00和679.00 mg.kg-1,土壤铜、锌和铅含量分别为297.00、276.00和51.40 mg.kg-1,铜、铬、镍、锌和铅的有效态比例分别为41.77%、13.16%、28.08%、21.50%和31.18%。去离子水、盐酸、乙酸、草酸、柠檬酸和EDTA 6种淋洗剂中,去离子水对5种重金属提取量均较少;草酸对铜、铬、镍和锌去除效果较好,去除率分别为55.1%、24.8%、47.5%和29.3%;柠檬酸对铜、铬、镍和锌去除效果较好,去除率分别为26.3%、25.7%、33.0%和21.6%;EDTA对铜、镍、锌和铅去除效果较好,去除率分别为31.5%、28.9%、21.4%和30.6%。综合考虑淋洗剂的提取效果、水溶性以及操作难度和成本,建议采用柠檬酸作为淋洗剂,最佳液土比〔V（液）∶m（土）〕为10∶1,最佳淋洗时间为6 h。     

Accumulation and translocation of heavy metals in soil and plants from fly ash contaminated area

The present investigation deals with the accumulation of heavy metals in fields contaminated with fly ash from a thermal power plant and subsequent uptake in different parts of naturally grown plants. Results revealed that in the contaminated site, the mean level of all the metals (Cd, Zn, Cr, Pb, Cu, Ni, Mn and Fe) in soil and different parts (root and shoots) of plant species were found to be significantly (p<0.01) higher than the uncontaminated site. The enrichment factor (EF) of these metals in contaminated soil was found to be in the sequence of Cd (2.33) > Fe (1.88) > Ni (1.58) > Pb (1.42) > Zn (1.31) > Mn (1.27) > Cr (1.11) > Cu (1.10). Whereas, enrichment factor of metals in root and shoot parts, were found to be in the order of Cd (7.56) > Fe (4.75) > Zn (2.79) > Ni (2.22) > Cu (1.69) > Mn (1.53) > Pb (1.31) > Cr (1.02) and Cd (6.06) approximately equal Fe (6.06) > Zn (2.65) > Ni (2.57) > Mn (2.19) > Cu (1.58) > Pb (1.37) > Cr (1.01) respectively. In contaminated site, translocation factor (TF) of metals from root to shoot was found to be in the order of Mn (1.38) > Fe (1.27) > Pb (1.03) > Ni (0.94) > Zn (0.85) > Cd (0.82) > Cr (0.73) and that of the metals Cd with Cr, Cu, Mn, Fe; Cr with Pb, Mn, Fe and Pb with Fe were found to be significantly correlated. The present findings provide us a clue for the selection of plant species, which show natural resistance against toxic metals and are efficient metal accumulators.     

Assessment of metal contamination in soil banks of the Rhumel wadi (Northeast Algeria)

Levels of six trace metals were assessed in bank soils of the Rhumel wadi (Northeast Algeria) and their association with soil properties was investigated. Samples were collected at 10 sites. The soils are neutral to moderately alkaline, have high contents of carbonate, and are low in organic carbon and clay. Mean metal concentrations are 1.1 (Cd), 63 (Cr), 20 (Cu), 26 (Ni), 31 (Pb), and 98 (Zn) mg kg^?1. The Cd, Cu, Pb, and Zn contents in soil from sites closest to Constantine City were higher than in uncontaminated soils worldwide, indicating accumulation due to human activities (residential, industrial, and agricultural). Statistical analyses (correlation and principal component analysis) demonstrated that Cd, Pb, and Zn are of anthropogenic origin in the urban areas, whereas Cr and Cu enrichment in some situations is caused by industrial activities, while Ni was geogenic.     

海南岛北部潮间带红树林对重金属的累积特征

对海南岛北部潮间带红树林湿地7种红树植物（根、茎、叶）及其根系沉积物中重金属元素含量进行了分析,结果表明：研究区湿地沉积物中Ni、Cu、Zn、As和Cd的变异系数大于0.50,沉积物中重金属分布很不稳定。其中Cr、Cu、Zn、As和Cd的含量均高于海南水系沉积物背景值,可能存在外源的输入。仅有Pb的含量略低于海南水系沉积物背景值。总体来看,大部分植物显示了对Cd元素的较强的富集能力（BAC〉1）,瓶花木对重金属元素的吸收能力总体上要比其他红树植物强一些,木果楝对重金属元素的吸收能力总体上最弱。其中,瓶花木（Scyphiphora hydrophyllacea）对Cr、Zn、As和Cd的吸收能力较强,莲叶桐（Hernandia sonora）对Cr和Ni的吸收能力较强,角果木（Ceriops tagal）对Pb的富集能力较强。角果木（Ceriops tagal）和桐花树（Aegiceras corniculatum）对Cd和Pb的运输能力较强,瓶花木（Scyphiphora hydrophyllacea）对Cu、Zn和Cd的运输能力较强,尖瓣海莲（Bruguiera sexangula）对Cr、Ni、Cd和Pb的运输能力较强,木榄（Bruguiera gymnorrhiza）对Ni、Cu、Cd和Pb的运输能力较强,木果楝（Xylocarpus granatum）对Cr、Zn和Cd的运输能力较强,莲叶桐（Hernandia sonora）对Cr也有较强的运输能力。但此次所研究的红树植物对As元素的运输能力均很弱,建议适量引入适宜在研究区生长并且对As元素富集能力较强的植物。     

Rieselfelder

Soils of the large sewage farm area south of Berlin are contaminated with heavy metals such as Cd, Cr, Cu, Hg, Ni, Pb, Zn. Based on earlier studies the total amount and the bioavailable proportions of heavy metals in soil samples were analysed. In some samples very high levels of total heavy metal concentrations were detected. For Pb, Cd, Cu and Hg the maximum values were 1360, 29.7, 817 and 40.8 mg/kg soil dry matter, respectively. The biovailable fractions of heavy metals which were found primarily in the acetate and EDTA fractions and to a lesser degree in the water extract account for about 50 % (Pb, Ni), 70 % (Cd) or 90% (Zn) of their total amount and may therefore pose a considerable environmental risk.     

Metal levels in computer monitor components discarded in the vicinities of electronic workshops

Levels of Pb, Ni, Cr, Cu, Zn, and Cd in the glass screens (GS) and printed wiring boards (PWBs) of obsolete computer monitors (OCMs) were determined by flame atomic absorption spectrophotometry (FAAS) following standard digestion. Metal concentrations (mg kg^?1) in GS were in the following ranges (medians in brackets): Pb ND – 3100 (46), Cd 0.5–2.6 (0.8), Cr ND – 18.7 (3.1), and Zn 8.1–600 (37) and in PWBs (mg kg^?1): Pb 34,600 ± 17,000, Cd 11 ± 9, Cr 59 ± 45, Zn 15,900 ± 7800, Cu79,000 ± 22,600, and Ni 3200 ± 2500. In GS, the levels of the six metals were lower than their total threshold limit concentrations (TTLC), except for Pb with a TTLC of 1000 mg kg^?1 in 10% of the samples. In the PWBs, the TTLC of Pb and Cu (2500 mg kg^?1) was exceeded many fold. For Zn (5000 mg kg^?1) and Ni (2000 mg kg^?1); they were exceeded by 90% and 65%, respectively. For OCMs manufactured in 2001 and later, Pb and Zn levels in GS and Cr, Zn, and Ni in PWBs were significantly reduced.     

淮南市城区地表灰尘重金属分布特征及生态风险评价

城市地表灰尘中重金属会对人体健康和生态环境产生危害,为研究城市中不同功能区地表灰尘重金属的含量和潜在生态危害水平,以典型煤炭资源型城市淮南市的地表灰尘为研究对象,采集工业区、商业区、交通区、文教区、居住区和公园绿地等6种功能用地共40个点位的地表灰尘。采用电感耦合等离子体发射光谱（ICP-OES）和DMA-80直接测汞仪测定Zn、Pb、Cu、Cr、Cd、Ni、Co、V、Hg的含量,分析其在不同功能区地表灰尘中的分布特征、相关性及可能的来源;并应用潜在生态危害指数法对重金属在不同功能区的潜在生态危害进行评价。结果表明：1）淮南市地表灰尘中 Zn、Pb、Cu、Cr、Cd、Ni、Co、V、Hg的平均质量分数分别是202.59、74.63、62.74、110.69、0.57、35.82、12.18、50.95和0.105 mg·kg-1,其中Zn、Pb、Cu、Cr、Cd、Ni、Hg的平均含量分别是淮南市土壤背景值的3.47、3.17、2.04、1.21、9.50、1.12、2.56倍,是中国土壤背景值的2.73、2.87、2.78、1.81、5.88、1.33、1.62倍。2）9种重金属中,Zn和V的含量在不同功能区分布相对均匀,其他重金属在不同功能区含量均表现出较明显的空间异质性。3）不同功能区中,Zn、Pb、Cu、Ni、Co、V、Hg的平均含量在工业区最高,Cr 和 Cd 的平均含量在交通区最高。4）不同重金属的相关性表明,Zn、Pb、Cu、Cd、Ni 等5种元素有同一来源,Co 和 V 有同一来源。5）单项潜在生态危害系数大小为 Cd〉Hg〉〉Pb〉Cu〉Ni〉Co〉Zn〉Cr〉V。不同功能区9种重金属复合生态危害均处于强生态危害水平（300≤RI〈600）,其中工业区和交通区潜在生态危害水平最高。     

Bioavailability and health risk assessment of potentially toxic elements in Thriasio Plain,near Athens,Greece

Elevated concentrations of potentially toxic elements (PTEs) are usually found in areas of intense industrial activity. Thriasio Plain is a plain near Athens, Greece, where most of the heavy industry of the country has been situated for decades, but it also is a residential and horticultural area. We aimed at measuring the levels of PTEs in soils and indigenous plant species and assessing the health risk associated with direct soil ingestion. Samples of soils at roadsides and growing plants were collected from 31 sites of that area. Concentrations of Al, As, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, V and Zn were measured in both soils (as pseudo-total) and aerial plant tissues. We found that As, Cd, Cr, Cu, Ni, Pb and Zn were higher than maximum regulatory limits. Element concentrations in plants were rather lower than expected, probably because indigenous plants have developed excluder behaviour over time. Copper and Zn soil-to-plant coefficients were highest among the other elements; for Cu this was unexpected, and probably associated with recent Cu-releasing industrial activity. Risk assessment analysis indicated that As was the element contributing more than 50 % of the health risk related to direct soil ingestion, followed by Cr, Pb, and, surprisingly, Mn. We concluded that in a multi-element contamination situation, elevated risk of PTEs (such as As, Cr and Pb) may reduce the tolerance limits of exposure to less-toxic elements (here, Mn).     

Metals concentration associated with respirable particulate matter (PM10) in industrial area of Eastern U.P. India

The present study deals with the assessment of ambient air quality with respect to respirable suspended particulate matter (RSPM or PM10 < or = 10 microm) and trace metals (Fe, Zn, Cu, Cr Ni, Cd, Mn and Pb) concentrations in RSPM at five locations of Renukoot, an industrial area of Eastern Uttar Pradesh. The 24 hr mean concentrations of PM10 ranged between 69.3 to 118.9 microg m(-3), which is well within the permissible limit (150 microg m(-3)) of national ambient air quality standards (NAAQS) but found higher than the prescribed annual daily limit of US EPA (50 microg m(-3)). The ambient air was mostly dominated by the Fe and least by the Cd among the metal analysed. Murdhawa, a commercial place influenced by vehicular population, is found to be the most polluted area of Renukoot and Dongia nalla (forest area) the least. The ambient air of Murdhawa is rich in Cu and Ni, indicating contribution of mobile sources. The Rammandir a residential place near the industry, is rich in Cd and Cr suggesting contribution of point sources. The Ni concentration is found to be alarmingly high in the air at all the locations except Dongia nallah, when compared with the EC (European Commission) limit (20 ng m(-3)). The Cd concentration is found to be higher only at Rammandir as compared with the EC limit (5 ng m(-3)). Mean concentrations of Zn, Pb and Mn are found to be almost equal in the ambient air of all the locations, suggesting the significance of sources contributing to presence of these metals. Zn, Cu, Pb and Ni having a significant correlation with PM10 indicate the same source contributing these metals as well as PM10. The present study has focused on the quantitative variation in different metals in the PM10, which is extremely harmful due to their toxic and carcinogenic nature.     

Phytoremediation of landfill leachate using Pennisetum clandestinum

Landfills are still the most widely used solid waste disposal method used across the world. Leachate generated from landfill areas exerts environmental risks mostly on surface and groundwater, with its high pollutant content, most notably metals, which cause an unbearable lower water quality. During dumping or after the capacity of the landfill has been reached, a decontamination and remediation program should be taken for the area. This study was conducted to assess the capacity and efficiency of Pennisetum clandestinum, a prostrate perennial plant, to accumulate chromium (Cr), copper (Cu), iron (Fe), nickel (Ni), zinc (Zn) and lead (Pb). Leachate, taken from the Sofulu Landfill Site, was given to Pennisetum clandestinum for 180 days, in 3 dilution sets as 1/1, 1/2 and 1/4, in batch configuration. An additional control set was also installed for comparison. Results showed that, even though the metal content of soil had risen, plants accumulated 2 to 8.5 times higher concentrations than the control set. It is important to see, the plant showed almost no stress symptoms even if the set was fed by pure leachate. Pennisetum clandestinum was observed to accumulate metals mostly in the upper bodies, excluding Fe and Cu. 76% of accumulated Cr, 85% of Ni, 66% of Zn and 100% of Pb was observed to accumulate in above-ground parts, where only 20% of Cu and 4% of Fe was accumulated. Due to the high pollution tolerance of Pennisetum clandestinum, makes this plant suitable for decontamination and remediation of landfill sites.     

深圳市内某河表层沉积物重金属含量及污染评价

2008年11月,从广东省深圳市内某河采集9个(0—5cm)表层沉积物样品,分析其Cu,Cd,Cr,Pb,Zn,Ni,As和Hg的含量和前6种元素的形态分布,并采用潜在生态风险指数法进行污染评价.结果表明,沉积物中Cu和Zn的含量普遍较高,为5.27—1865mg.kg-1和198.4—1275mg.kg-1,其次是Cr,Ni和Pb,为54.39—908.7mg.kg-1、31.3—445.5mg.kg-1和11.63—814.9mg.kg-1,As,Cd和Hg的含量较少;Cd的残余晶格态、Cr的铁/锰氧化态和残余晶格态、Cu的有机结合态和残余晶格态,以及Ni,Pb和Zn的铁/锰氧化态为各元素的主要存在形态;沉积物中Cd和Cu的潜在生态风险普遍较大,9个样品中6个达到Cd极强生态危害,4个达到Cu很强生态危害,有5个样品的重金属混合污染潜在生态风险达到极强生态危害.     

Heavy Metals Contamination of Topsoil in the Vicinities of Auto-Repair Workshops,Gas Stations and Motor-Parks in a Nigerian City

Concentrations of Pb, Zn, Cd, Cu,Cr, Co and Ni were determined in topsoil obtained from vicinities of auto-repair workshops, gas-stations and motor-parks in Ibadan, Nigeria. The levels were elevated above background concentrations in control sites. Lead and copper were the most significant contaminants, and the degree of contamination was highest in auto-repair workshops. Factors of accumulation for Pb and Cu were: auto-repair workshops: Pb - 95.8, Cu - 117; gas stations: Pb - 46.6, Cu - 33.5; motor-parks: Pb - 31.6, Cu - 16.8. For Zn, Cd, Cr, Co and Ni, the factors of accumulation were much lower and did not vary much among the three study areas. Average values for all locations were: Zn - 5.2, Cd - 4.4, Cr - 3.7, Co - 1.5, Ni - 1.7. Improper disposal of waste lubricants is the likely source of high copper contamination.