Heavy metals in the polychaete Glycera longipinnis from the southwest of India

Metal concentrations in sediment and in whole tissue of the benthic polychaete Glycera longipinnis collected along the southwest coast of India were analysed. Relative seasonal accumulation of metals (Cu, Pb, Cr, Ni, Zn, Cd, Hg) was studied by categorising the habitat as less polluted or highly polluted based on metal contamination routed through industrial and urban sources. The metal content in tissues varied seasonally in the ranges, Cu: 2.21–27.08 μg·g^?1, Pb: 0.06–4.92 μg·g^?1, Cr: 1.73–29.20 μg·g^?1, Ni: 1.60–4.61 μg·g^?1, Zn: 14.72–82.30 μg·g^?1, Cd: 0.04–1.38 μg·g^?1and Hg: below decetable limits to 0.86 μg·g^?1. Concentration of heavy metals was found to be high in the whole body of G. longipinnis pooled from the polluted transects. The results of this study suggest that G. longipinnis may act as a useful biological indicator for heavy metal pollution along the southwest coast of India.     

Assessment of enrichment,geo-accumulation and ecological risk of heavy metals in surface sediments of the Msimbazi mangrove ecosystem,coast of Dar es Salaam,Tanzania

Results of the assessment of enrichment, accumulation and the ecological risk associated with three heavy metals (Cd, Cu and Pb) and one metalloid (As) in surface sediments of Msimbazi estuary are presented. Surface sediment samples (0–5 cm) were collected from Msimbazi River estuary in September 2016 using handheld PVC short corers. Long-sediment cores from the site were also collected using PVC pipes and their vertical profiles of metals concentrations assessed with the aim of establishing site-specific baseline metals concentrations. The established site-specific baseline values were used for the determination of normalised enrichment factors (EF) and geoaccumulation (Igeo) of metals instead of using average crustal values. Iron-based enrichment factors show that the sediments of Msimbazi have experienced enrichment of metals that originate from anthropogenic sources of pollution (EF > 1). Geo-accumulation results indicate that Msimbazi sediments can be designated as uncontaminated to moderately-contaminated with As, Cd and Pb (class 1–2). Geoaccumulation indices for Cu indicate that sediment can be designated as uncontaminated to moderately contaminated (class 1) and moderately to strongly contaminated (class 3). Results show further that the Ecological Risk associated with the accumulation of these metals in Msimbazi sediments was low based on Hakanson approach.     

Heavy metal contamination in river water and sediments of the Swarnamukhi River Basin,India: risk assessment and environmental implications

The concentration of heavy metals was analyzed each of 20 river water, suspended sediments and bed sediments along the stretch of Swarnamukhi River Basin. River water is not contaminated with heavy metals except Fe and Mn. Contamination factor in sediments shows considerable to very high degree contamination with Cr, Cu, Pb and Zn. The sources of these metals could be residential wastes, sewer outfall, fertilizers, pesticides (M-45 + carbondine) and traffic activities apart from natural weathering of granitic rocks present in the basin area. Principal component analyses indicate the interaction between metals in different media. The comparison of metals (Cu, Pb and Zn) in bed sediments of Swarnamukhi River with the Indian and world averages indicates that the values obtained in the basin are above the Indian averages and far below to the world averages. Average shale values and sediment quality guidelines point toward the enrichment and contamination of Cu, Cr, Pb and Zn to several fold leading to eco-toxicological risks in basin.     

Threat of heavy metal contamination in eight mangrove plants from the Futian mangrove forest,China

Mangrove plants play an important role in heavy metal maintenance in a mangrove ecosystem. To evaluate the characteristics of heavy metal contamination in the Futian mangrove forest, Shenzhen, China, eight heavy metals in mangrove sediments and plants were monitored, including essential elements such as Cu and Zn, and non-essential elements such as Cr, Ni, As, Cd, Pb and Hg. The results showed that the heavy metals exhibited the following scheme: Zn > As > Cu ≈ Cr > Pb > Ni > Cd ≈ Hg in sediment cores, among which Cd, As, Pb and Hg contents were nearly ten times higher than the background values. There was no significant difference in metal maintenance capability between native and exotic species. In mangrove plants’ leaves and stems, concentrations of Cu, Zn and As were higher than other heavy metals. The low bioconcentration factors for most heavy metals, except for Cr, implied the limited ability of heavy metal accumulation by the plants. Mangrove plants seem to develop some degree of tolerance to Cr. The factor analysis implies that anthropogenic influences have altered metal mobility and bioavailability.     

Assessment of toxicity of heavy metal contaminated soils by the toxicity characteristic leaching procedure

The concentrations of Cu, Zn, Pb and Cd in soils near a lead–zinc mine located in Shangyu, Zhejiang Province, China, were determined and their toxicity was assessed using the toxicity characteristic leaching procedure (TCLP) developed by the United States Environmental Protection Agency. The TCLP method is a currently recognized international method for evaluation of heavy metal pollution in soils. The available levels of Cu, Zn, Pb and Cd were 8.2–36, 23–143, 6.4–1367 and 0.41–2.2 mg kg⁻¹, respectively, while the international standards were 15, 25, 5 and 0.5 mg kg⁻¹, respectively. Soils around the mine were more polluted with Zn and Pb, followed by Cd and Cu. Moreover, the levels of heavy metals in the soils extracted by TCLP indicated that extraction fluid 2 was more effective than extraction fluid 1 in extracting the heavy metals from the polluted soils and there was a positive correlation between fluids 1 and 2. Available heavy metal contents determined by TCLP were correlated with soil total heavy metal contents.     

莱州湾表层沉积物中重金属时空分布、污染来源及风险评价

运用污染风险评价标准和方法研究了2010年5月(春)、8月(夏)、10月(秋)和12月(冬)莱州湾表层沉积物中7种重金属污染物的时空分布特征、来源及生态风险。结果表明,表层沉积物中Cr、Zn和Pb含量均呈现春季低于其他季节特征,秋季Hg含量是其他季节的4倍,Cu、As和Pb含量无显著季节差异。表层沉积物中Cr、Cu、Zn、As和Cd最高值出现在莱州湾中部及小清河河口等西部水域,来源呈现受自然作用影响较大的特征;而Hg和Pb最高值出现在龙口和界河河口等东部水域,来源呈现受周边工业污染物的人为排放影响较大的特征。基于地理累积指数、生态效应浓度以及Hakanson潜在生态风险指数的综合评价表明,13%~29%的研究区域的表层沉积物受到轻微程度的Cd、Hg和Pb污染,Cd和Hg高值水域达到中等生态风险程度;Hg和As在65%~68%的研究区域的表层沉积物中达到可能对沉积物底质环境及生物群落产生不利生态影响水平。基于对重金属污染物的评价结果,莱州湾表层沉积物质量较好,局部区域存在Hg、Pb、Cd和As的潜在污染风险。     

Heavy metals and organic carbon in sediments from the Tuy River basin,Venezuela

The Tuy River basin, located in north-central Venezuela with an annual average temperature of 27°C and precipitation of 140 cm, was selected to conduct a geochemical study of bottom sediments, with the object of establishing the natural and human influences in the abundance and distribution of Fe, Mn, Cr, Co, Cu, Ni, Pb, Zn and organic carbon. The basin is lithologically divided into two sub-basins, north and south. The north sub-basin drains a iow-grade metasedimentary terrain with a population density of 800 persons km^–2 and approximateiy 600 industrial sites, while the south sub-basin in underlain by metavolcanic and ultramafic rocks, with a population density of less than 10 persons km^–2.Stream bottom sediment samples (150) were collected during the years of 1979–1986 in 16 unpolluted sites and 13 polluted sites. The sediments were air dried at room temperature and sieved through a 120 stainless steel mesh (125 m). Samples of grain size smaller than 125 m were analysed, the heavy metals being determined by atomic absorption spectrometry and the organic carbon (Corg) by dry combustion.The higher concentrations of heavy metals and organic carbon found in the pristine areas were in the south sub-basin, especially in those areas with higher annual precipitation and tropical forest. This indicated that the metavolcanic and ultramafic rocks yield higher concentrations of heavy metals than the metasedimentary rocks. It was also noted that the higher concentrations of Cr and Ni are associated with the ultramafic rocks. The results obtained from the sediment samples collected in the polluted sites showed that the elements Pb, Zn and Corg are enriched up to 4 times as a result of ail the human activities taking place in the basin. Organic carbon is an excellent indicator of domestic wastewater, Pb and Zn are good indicators of the automotive traffic and industrial effluents. The concentrations of each heavy metal did not show any significant correlation with grain size fractions; however, the concentration of organic carbon did show a negative correlation with grain size. The lithological, climatic and vegetation influence in the abundance of heavy metals and organic carbon in stream sediments clearly indicates the necessity of establishing background levels for the area under study when carrying out studies in environmental geochemistry.     

Anthropogenic metal pollution in surface sediments of the Tambaraparni River Estuary

Estuarine sediments in the<63 μm size fraction were collected from 15 stations within the Tambaraparni River Estuary, located on the east coast of India. The distribution of the heavy metals Cd, Co, Cr, Cu, Ni, Pb and Zn was recorded. Our analysis distinguished two groups of elements. First, Cd, Pb and Zn, which occurred in higher than expected concentrations indicative of pollution, and second, Co, Cr, Cu and Ni, which occurred at background levels. The highest metal concentration found in the study area was for Zn (1200 μ g·g^?1), and the lowest was for Cd (0.42 μ g·g^?1). It is presumed that river run-off, industrial waters and untreated domestic waters are major contributors to heavy metal pollution in the Tambaraparni River Estuary. The concentrations of heavy metal species in surface sediments (<2 m water depth) of the Tambaraparni Estuary were studied to determine the extent of anthropogenic inputs from catchment areas and to understand anthropogenic effects on geochemical process in this tropical estuarine system.     

Fraction distribution and migration of heavy metals in mangrove-sediment system under sulphur and phosphorus amendment

In this study, mangrove seedlings (Kandelia obovata (S. L.)) were cultivated in rhizo-boxes, which contain sediments collected from natural mangrove forest and modified with different rates of sulphate and phosphate. The fraction distributions of Zn, Cd, Cu, Ni and Pb in rhizosphere and non-rhizosphere sediments were studied by using a sequential extraction method. Metal concentrations in plant tissues and iron plaque on root surface were also determined to reveal migration variation of heavy metals in the plant-sediment system. The results showed that the activities of K. obovata roots enhance the reducible metals while reducing acid-extractable and oxidisable metals; sulphur amendment benefits the combination of metal ions with S^2– and therefore reduces the bioavailability of metal pollutants; addition of sulphur also improves the content of iron plaque on the root surface, which plays an important role in metal accumulation by K. obovata root tissue; the addition of sulphur markedly reduces the concentration of Cd in roots, but significantly enhanced the concentrations of Cu, Zn, Ni and Pb in roots. The results indicate that sulphur and phosphorus content in mangrove sediment, and the growth of mangrove plant can significantly influence the migration of heavy metals in the mangrove wetland ecosystem.     

Evaluating heavy metal contamination of riverine sediment cores in different land-use areas

• Metal pollution was studied in riverine sediments from different land-use areas. • Cd was the most serious heavy metal contaminant in riverine sediment cores. • Riverine sediment cores from industrial area were most polluted by heavy metals. • B1 fraction determined metal pollution, risk and toxicity in riverine sediments. Anthropogenic activities are regarded as the main sources of heavy metal pollution, yet few studies have investigated the effects of land-use setting on heavy metal accumulation in riverine sediments. Based on both total contents and geochemical fractions, heavy metal pollution, risk and toxicity were determined in riverine sediment cores from different land-use areas (mountain area- MA, farm area- FA, city area- CA, and industrial area- IA) of the Yang River Basin in North China. The results showed that FA had higher contents of riverine sedimentary Cu; CA had higher contents of Cd; IA had higher contents of both Cd and Zn. Most riverine sediments from FA and IA were contaminated with the investigated metals, although these concentrations were evaluated to have low potential ecological risk and no toxicity to benthic organisms. However, a high proportion of Cd in the B1 fraction of riverine sediments in IA indicating high risk should receive more attention. The B1 fraction largely determined the contamination, risk and toxicity levels associated with heavy metals in the riverine sediments of the Yang River Basin.     

Fractionation of Heavy Metals in Surface Sediments of Taihu Lake, East China

The BCR (European Communities Bureau of Reference) three-step sequential extraction procedure was applied to fractionate heavy metals in the sediment of Taihu Lake. For the determination of total metal concentration of the sediments, sample digestion was achieved by using HF/H₂O₂/HNO₃(2/1/1) acid mixture in a microwave-irradiated closed vessel system. The concentrations of Cd, Ni, Cr, Zn, Cu and Pb in various extracts solutions were analyzed by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES). The results obtained from the BCR three-step sequential extraction indicated relatively high mobility of Zn, Cu, Pb and Ni in the sediments while Cd and Cr were poorly mobile. Enrichment of heavy metals was found in the sediments collected in the northern parts of Taihu Lake. In the sediments collected in the southern and western sides of the Lake, heavy metal concentrations were relatively low. The relationship between total organic carbon (TOC) and heavy metals concentrations in the sediments is discussed.     

Seasonal Variations of Trace Metal Chemical Forms in Bed Sediments of a Karstic River in Lebanon: Implications for Self-purification

Although Lebanon has abundant water, its rivers are polluted and aquifer water mismanaged. Effective river water usage requires an understanding of the geochemistry of polluting metals in catchments. Climate is “Mediterranean”: wet winters and dry summers. Active sediment flushing is restricted to winter high discharge episodes. Except in winter, water column pollutants are removed by precipitation or sorption to the surface of static bed sediments. Hence (1) does winter flushing of contaminated sediment and replacement by clean sediment favour self purification? (2) does the distribution of metals between extractable fractions change seasonally and thereby affect metal bioavailability ? Results on the distribution of metals are reported for Fe, Pb, Zn, Cu and Cd in bed sediments from Nahr Ibrahim (a karstic river) for summer and winter. A Tessier-like sequential extraction scheme was applied to samples (< 75 μm) for five locations along a 13 km stretch to the sea. Water pH was above 8.2 at all locations implying a very low solubility for Fe. Sediment was derived from catchment soils and limestone. Total sediment Fe increased in winter at all sites following deposition of eroded soil from upstream. Cadmium, Cu and Pb derived from polluting sources; the sources of Zn were more complex. Dilution by clean sediment explained winter reductions in total Cd, Cu and Pb; Zn changes were less consistent. Iron occurred mostly (> 77 sum of fractions) in the residual fraction compared with 6– 31 for pollutants; residual Cu and Zn showed a small increase in winter whereas Cd and Pb did not change. All readily exchangeable metals decreased in winter and the carbonate bound forms predominated in both seasons. Nahr Ibrahim has a high capacity for self purification and metal resolubilisation from sediment will be limited by the solubility of carbonate forms.     

电子废物不当处置的重金属污染及其环境风险评价 Ⅳ. 电子废物不当回收地区流域水体沉积物的重金属污染

为了解电子废物不当处置活动对小流域内水体沉积物金属污染的影响,采集了位于广东省清远市龙塘镇和石角镇的电子废物焚烧和酸解活动核心区内水塘和水库的0～40cm沉积物以及附近河流大燕河表层(0～5cm)沉积物样本,分析了样本中的金属(水塘、水库:Zn、Cu、Pb、Cd、Cr;大燕河:Zn、Cu、Pb、Cd、Cr、Ni、Mg、Mn)含量.作为对照,对珠江口伶仃洋沉积物中的5种重金属(Zn、Cu、Pb、Cd、Cr)含量也进行了分析.结果表明,1)在核心区内,5种重金属的平均含量在接近酸解作坊的水塘沉积物中呈Cu(766.16mg·kg-1)>Zn(181.12mg·kg-1)>Pb(129.56mg·kg-1)>Cr(1.89mg·kg-1)≈Cd(1.12mg·kg-1),在其下游的水库沉积物中呈现相同的规律,但水塘沉积物的Cu、Zn、Pb含量均高于水库.水塘、水库沉积物重金属含量分布规律明显不同于伶仃洋沉积物,与伶仃洋沉积物相比,核心区水体沉积物Cu含量特别高,是伶仃洋沉积物的7～17倍,Pb和Cd则分别是伶仃洋的2.3～3.0倍和1.9～2.4倍,Zn、Cr含量与伶仃洋沉积物相近.2)Zn含量在核心区水体沉积物中均呈现出在20.0～30.0cm深度最高的趋势,Cu、Pb含量在水库沉积物中也有类似的表现,说明该深度的沉积物可能是电子废物回收处置活动最频繁的时期形成的,近年来随着政府取缔工作的加强,电子废物非法处置活动的减少,Zn、Cu、Pb含量有明显的下降.3)大燕河沉积物中6种重金属(Zn、Cu、Pb、Cr、Cd、Ni)的总含量表现为中游下段(1261.3mg·kg-1)>中游中段(1049.2mg·kg-1)>中游上段(401.8mg·kg-1)>上游(364.6mg·kg-1)>下游(215.4mg·kg-1).Cu、Zn、Pb和Cr含量均在中游下段的沉积物中出现最大值,次大值出现在中游中段,Ni、Cd在中游中段出现最大值,次大值出现在中游下段.中游中、下段沉积物中金属含量最大值和其上游(或中游上段)河段含量最低值的比值呈现Cu(10.1)>Cr(7.8)>Zn(3.8)>Cd(2.0)>Pb(1.9)>Ni(1.8),显示这些重金属主要从中游中、下段进入大燕河沉积物,其中Cu污染最为严重,而Cr污染可能与水土流失或当地其他活动释放的Cr有关.4)比较流域内土壤和各种沉积物以及伶仃洋沉积物中重金属的构成比例发现,核心区土壤和沉积物以及大燕河沉积物中的重金属具有明显的同源性.随着离源区距离的增加,重金属的构成比例中最明显的变化是Cu的比例下降以及Zn的比例上升。     

Metallic contaminant profiles in sediment cores from Lake Valencia,Venezuela

Total extractable concentrations of AI, Fe, Mn, Pb, Cu, Zn, Hg and organic carbon (C_org) were determined along four sediment cores from Lake Valencia. In one selected core, the percentage labile fractions were determined in order to establish anthropic enrichment factors, the depth reached by the contaminants and their mobilities. The distribution patterns of concentration versus depth reflect the original concentrations of the settling sediments. Only Mn seems to show diagenetic cycling. No enrichment of Fe and Mn occurs in the upper part of the cores, in spite of good water circulation and aeration of bottom lake waters during five months of the year. This immobility can be attributed to the high pH of water (7.6 – 8.9). Pb, Zn, Cu and Hg are enriched in the upper part of the cores, probably reflecting the input of contaminants. These elements show enrichment factors of up to 3.0. Background concentrations of the studied metals are reached below a depth of 30 cm.     

羟基磷灰石对沉积物中重金属释放特性的影响

以羟基磷灰石掺杂前后模拟重金属污染沉积物为研究对象,利用混匀释放实验及化学连续萃取法分析沉积物中重金属的释放特征及形态分布特性,考察了羟基磷灰石对重会属污染沉积物中Cu、zn、Pb、Cd稳定性的影响.结果表明不同来源模拟污染沉积物中松花江沉积物中的重金属最易重新释放,而伊通河沉积物中的重金属释放量最小;同时伊通河沉积物中残渣态重金属的比例较其它沉积物高很多,而可交换态和碳酸盐结合态的重金属比例较其它沉积物低很多,说明同时进入沉积物中的重金属,伊通河沉积物中的重金属相对稳定一些.羟基磷灰石的掺杂不同程度降低了沉积物中重金属的释放能力,促使沉积物中的重金属由较不稳定结合态向较稳定结合态转化,减小了沉积物中重金属的生物可利用性,增强了重金属的稳定性.     

Seasonal variation of heavy metals in sediment of Lake Ulansuhai,China

Sediment samples were collected from 10 sites in Lake Ulansuhai during summer and winter 2009 to reveal seasonal variations in sediment heavy metal levels. The geoaccumulation index (GI) was calculated to assess the severity of metal pollution. The GI values suggest that, in winter, the lake sediments were polluted slightly with Cu (GI=0.66–1.34), Zn (GI=0.59–1.35), Cr (GI=0.49–0.82) and Pb (GI=0.60–0.96), and moderately with Cd (GI=1.03–4.23). The degree of pollution was higher in winter than in summer. By contrast, the degree of pollution was higher in summer than in winter for Hg and As. Correlation analysis can be used to identify factors influencing seasonal variations in heavy metals. The concetrations of Cu, Zn, Pb, Cr and Cd were negatively correlated with water temperature and hydrodynamic conditions, but positively correlated with organic matter concentration in the sediments and with a sediment particle size of<63 μm (p<0.01). Meanwhile, Hg and As concentrations were affected by redox state and salinity. Among the metals tested, Hg and Cd posed a more serious pollution risk.     

A century-long trend of metal pollution in the Sheyang River,on the coast of Jiangsu (China), reconstructed from sedimentary record

In order to reveal the historical context of metal element accumulation under the economic boom during the last decades in eastern China, concentrations of nine metal elements, radionuclides (²¹⁰Pb), Pb isotope ratios (²⁰⁷Pb/²⁰⁶Pb) and sedimentary characteristics were investigated in two sediment cores collected from the Sheyang River. The sediments have recorded the heavy metal deposition and thus allow establishing a connection between the temporal evolution of the heavy metal pollution and historical changes in industrial and urban discharges. Enrichment factors (EFs) were calculated to estimate the level of contamination in these sediments. A significant anthropogenic enrichment of Cu, Ni, Pb, Cr and Zn was highlighted, which were identified from anthropogenic discharges from cities and industrial sources, according to a cluster analysis. According to the annual variation in GDP growth rate, industrial growth rate, ratio of ²⁰⁷Pb/²⁰⁶Pb and EFs, it was obvious that sedimentary accumulation of metals has a close relationship with anthropogenic activities. In the pre-industrial period, natural inputs prevailed with lower EF and constant ²⁰⁷Pb/²⁰⁶Pb ratios around 0.82. However, during 1980–1995, the rapid industrial development caused a gradual increase in EFs and ²⁰⁷Pb/²⁰⁶Pb (>0.83). Our results disinterred the evolution of anthropogenic metal inputs in the last century into the Sheyang River.     

Heavy metals associated with reduced sulfur in sediments from different deposition environments in the Pearl River estuary, China

Distribution of acid volatile sulfur (AVS) and the simultaneously extracted metals (SEM: Cu, Pb, Zn, Cd, Ni) in sediment profiles has been studied at five sites in Pearl River estuary, China. Of the five sampling locations, Nos.1 and 2 are in the middle shoal, Nos.3 and 4 in the west shoal and No. 5 locates to the south of the estuary. The AVS content in the sediments of the middle shoal varies in a small range (0.25–4.06 μmol g⁻¹), while that of west shoal increases with depth from 0 to ultimately 26.09 μmol g⁻¹. The SEM concentration in the sediment profiles at location Nos. 1, 2 and 5 is generally in the range of 0.95±0.2 μmol g⁻¹ with a slight upward increase, while that in the sediment of west shallows are much higher (1.43–2.42 μmol g⁻¹) with a significant upward increase, especially in the upper layer of ca. 15 cm. The observed upward increase of SEM content at all the sites implies that heavy metal contamination of sediment in the Pearl River estuary is increasing. Calculations of the excess heavy metal content which is defined by SEM-AVS molar difference suggests that the upper sediment in the Pearl River estuary, especially on the west shallows, could be a source of heavy metal contaminants and may cause toxicity to the benthos. The site-specific distribution patterns in the AVS and SEM profiles were interpreted according to the hydrogeochemistry of deposition environments.     

珠海近岸海域表层沉积物中的重金属及生态危害评价

为了研究珠江口近海海域重金属的污染状况,2009年8—12月对珠海珠江口4个站点的表层沉积物进行了6次采样,测定了表层沉积物中重金属Cd、Cr、Pb、Hg、Cu、Zn、Mn、Ni、Fe和金属Al的质量分数,分析了它们质量分数间的相关性,依据Lars Hakanson提出的沉积物中金属污染物评价方法,对Cd、Cr、Pb、Hg、Cu和Zn等6种典型重金属的潜在危害进行了评价。结果表明,Cd、Cu和Zn是该调查区域的主要重金属污染物,应该予以优先控制和治理。位于马骝洲水道入海口的S1位点上,金属元素（Cd除外）质量分数的季节特征是秋季（丰水期）〈冬季（枯水期）,重金属危害指数（RT）为轻微级,重金属潜在生态危害系数（Eir）顺序为Cd〉Hg〉Pb〉Cu〉Zn〉Cr;在S2位点,Cd、Cu、Hg、Ni和Fe的平均质量分数为秋季〉冬季,其它5种金属则为秋季〈冬季,RT为强级;在S3、S4位点上,8种金属元素（Hg、Mn除外）的质量分数呈现秋季〉冬季的现象,RT为很强级;S2、S3和S4站点的Eir均表现为Cd〉Hg〉Cu〉Pb〉Zn〉Cr的顺序。     

蚯蚓对垃圾与底泥中镉的富集现象

通过蚯蚓处理垃圾及纳污河流底泥实验研究发现蚯蚓可选择吸收并富集垃圾及底泥中的镉，但对其他重金属元素铅、铜、锌等并无此种富集吸收现象。