Metal Contamination Status Research Articles

Assessment of Heavy Metal Enrichment and the Degree of Contamination in Coastal Sediment from South East Coast of Tamilnadu, India

Assessment of heavy metals in coastal sediments from Thazhankuda to Kodiyakkarai along the East Coast of Tamilnadu, India was carried out using Energy dispersive X-ray fluorescence (EDXRF) technique with the computation of different pollution indices. The mean order of metal concentration is Al>Fe>Ca>K>Mg>Ti>Mn>Cr>V>Zn>Ni>Co in the study area. The locations of Pichavaram (CPM), Tharangambadi (TRGB) and Karaikal (PKK) were found to be moderately polluted by heavy metals due to anthropogenic activities. The pollution indices such as Contamination factor (CF), Pollution load index (PLI), Contamination degree (Cd), modified degree of contamination (mCd), Potential contamination index (Cp) and potential ecological risk index (RI) were used for the metal enrichment and contamination status. The CF and PLI value of the present work indicating that the sediments are not polluted by heavy metals. The calculated Contamination degree (Cd), modified degree of contamination (mCd), Potential contamination index (Cp) and potential ecological risk index (RI) of the studied metals indicated that the study area does not posed high risk to local environments.

남해안 패류양식해역(여자만과 강진만)의 퇴적물내 미량금속 분포특성 및 오염도 평가

남해안 패류양식해역(여자만과 강진만)의 퇴적물내 미량금속 분포특성 및 오염도 평가

Monitoring Heavy Metal Contamination Using Rocky Oyster (Saccostrea glomerata) in Haiphong-Halong Coastal Area, North Vietnam

To understand the present status of metal contamination along the Haiphong-Halong coast, the concentrations of As, Cd, Cr, Cu, Pb, and Zn were seasonally determined in rock oysters from four sites during 2013. The results indicated that a high concentration of heavy metals was found in oysters. The average concentrations of Zn and Cu were extremely high, ranging from 823.6–3201.6 and 238.1–1597.8 mg/kg dry wt., respectively, followed by As, Cd, Pb and Cr with concentrations of 10.10–19.33, 3.53–12.74, 0.79–6.20, and 0.81–4.47 mg/kg dry wt., respectively. The highest concentrations of heavy metals, Cd, Cr, Pb and Zn, found in Dinh Vu were attributed to anthropogenic inputs. In addition, the runoff in the rainy season greatly influences the accumulation of heavy metals in oysters from Dinh Vu and Do Son. The maximum levels of Cd, Cu, Zn and As could be potentially creating toxicological concerns from human health point of view and rocky oysters from the polluted sites should not be consumed.

Assessment of heavy metal contamination status in sediments and identification of pollution source in Daye Lake, Central China

This research presents a detailed study which was performed to infer the quantity of metal (Cd, Cr, Pb, Zn, Cu and Fe) contents in sediments of Daye Lake, Central China. The geo-accumulation (I geo) and potential ecological risk (PER) of these metals were assessed. The results reveal that: (1) the mean value of I geo ranked an order of Fe (class 6) > Cd (class 5) > Pb (class 3) > Zn (class 2) > Cr (Class 1) > Cu (Class 0); (2) Potential ecological risk (PER) values calculated for all these metals at different sampled points in Daye Lake exceeded the value of very high risk. Multivariate statistical analyses were carried out to determine the relationship between these six metals and to identify the possible pollution sources, with the results suggesting that the metal content in the sediments has three patterns: the first pattern includes Pb, Cd and Cr which were mainly present due to discharged water by smelting industries; second pattern contains Zn and Cu which mainly originated from the waste residue of the copper mining industry; the third pattern is Fe which is mainly related to mine tailing leaches. This study indicates very high metal content levels in the sediments, which may have adverse risks (average PER = 7,771.62) for the lake’s ecosystem and human beings associated with Daye Lake.

Distribution and Contamination Status of Trace Metals in the Mediterranean Coastal Sediments, Egypt

Trace metals concentrations in sediments from the Egyptian Mediterranean coast were determined to evaluate the levels of contamination. The highest concentrations of metals were generally found in the middle region of the coast. Sediment pollution assessment was carried out using Enrichment Factor (EF), Geoaccumulation Factor (Igeo), Contamination Factor (CF), Modified Degree of Contamination (mCd), and Pollution Load Index (PLI). Association of adverse effects to aquatic life was determined using the classification of sediments according to three sets of sediment quality guidelines. The mean EF values were found to fall in the following sequence: Cr > Pb > Ni > Zn > Cu > Mn. The results demonstrated that the EF of metals in the sediments of the middle region was lower than those recorded in the western region and Rafah Station at the eastern region; the difference in the EF levels was significantly correlated with Fe concentrations along the study area. Based on the average Igeo of target elements, the Egyptian Mediterranean coast could be considered not polluted with Cr, Cu, Mn, Ni, Pb, and Zn (Igeo ≤ 0). The modified degree of contamination was >1.5, indicating zero to very low contamination. The calculated PLI were less than 1, indicating only baseline levels of pollution. There were small differences between the results obtained with the three used SQGs. Highly significant correlations were found between the concentrations of Fe, Mn, Co, Cr, and Ni, suggesting similar sources and/or similar geochemical processes controlling the occurrence of these metals in the sediments.

湘南某矿区蔬菜中Pb、Cd污染状况及健康风险评估

PDF HTML阅读 XML下载 导出引用 引用提醒 湘南某矿区蔬菜中Pb、Cd污染状况及健康风险评估 DOI: 10.5846/stxb201212251868 作者: 作者单位: 中南林业科技大学林学院环境科学与工程研究中心,中南林业科技大学环境科学与工程研究中心,中南林业科技大学环境科学与工程研究中心,长沙环境保护职业技术学院,中南林业科技大学环境科学与工程研究中心,中南林业科技大学环境科学与工程研究中心 作者简介: 通讯作者: 中图分类号: 基金项目: 环保部公益项目（201009047）；湖南省环境科学重点学科建设项目（2006180） Contamination status of Pb and Cd and health risk assessment on vegetables in a mining area in southern Hunan Author: Affiliation: Research Center for Environmental Science and Engineering, Central South University of Forestry and Technology,,,,,Research Center for Environmental Science and Engineering, Central South University of Forestry and Technology Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:通过采集湘南某矿区周边农田中种植的蔬菜和对应耕作层土壤样品，探究了农田蔬菜Pb、Cd的污染状况，蔬菜和土壤重金属含量之间的相关性，蔬菜中重金属对人体的健康风险。结果表明：（1）污染区土壤重金属污染非常严重，叶菜类蔬菜重金属超出了食品卫生标准限值，但是果菜类蔬菜中重金属没有超出食品卫生标准限值。（2）不同蔬菜不同器官所含Pb、Cd有明显差异；不同种类蔬菜Pb、Cd含量不同，一般是叶菜类 > 果菜类；同种蔬菜不同部位重金属含量的顺序也不同，一般为根 > 茎 > 叶 > 果，或根 > 叶 > 茎 > 果。（3）二类蔬菜中重金属Pb、Cd的富集系数顺序为叶菜类 > 果菜类。（4）蔬菜中Pb、Cd含量与土壤中相对应元素含量均无显著相关性。（5）就农产品安全性而言，果菜类蔬菜比叶菜类蔬菜更适合在此矿区栽培。 Abstract:Vegetables, including leafy vegetables and fruit, are of importance to human health. In order to evaluate the heavy metal contamination status and associated health risks of vegetables, 57 vegetables (34 spring vegetables and 23 winter vegetables) and 34 corresponding soil samples (sampled with the spring vegetables) were collected from farmland surrounding a mining area in southern Hunan, China. Analysis was carried out to determine the correlation between the heavy metal content of vegetables and soils, to enable assessment of the potential health risk to local inhabitants consuming the vegetables grown in the contaminated soils. The results showed that: (1) The measured maximum total Pb and Cd in the soils were up to 1251.9 mg/kg (the corresponding soil to the three-colored amaranth) and 13.2 mg/kg (the corresponding soil to the kidney bean), respectively. The average concentration of total Pb and Cd in all soils were 841.7 mg/kg and 6.5 mg/kg, respectively, which were 3.37 and 21.67 times the standard allowable concentration of Pb and Cd for vegetable soils in China (pH level < 6.5, Pb ≤ 250 mg/kg, Cd ≤ 0.3 mg/kg; Environment Quality Standard for Soil Heavy Metals GB15168-1995, Grade Ⅱ). It suggested that contamination from heavy metals in these soils was very serious. (2) Vegetables grown on the contaminated soils were rich in Pb and Cd in different plant organs. The highest levels of heavy metals were 5.03 mg/kg for total Pb and 2.92 mg/kg for total Cd in the edible parts of garlic and three-colored amaranth, respectively, which exceeded the maximum levels of the China National Food Sanitation Standards for total Pb (GB 14935-94, 0.2 mg/kg) and Cd (GB 15201-94, 0.05 mg/kg). The heavy metal content of leafy vegetables, not fruit, exceeded the China National Food Sanitation Standards for Heavy Metals. The contents of total Pb and Cd in different organs of the vegetables were quite different and generally followed a sequence of root > stem > leaf > fruit, or root > leaf > stem > fruit. Pb and Cd contents in leafy vegetables were generally higher than those in fruits. (3) The order of bioaccumulation factors (BFs) of heavy metals in the two vegetable types was leafy vegetables > fruits. Based on fresh weight, the average BFs of Pb varied within (0.7-8.4)×10-3 for leafy vegetables and (0-0.02)×10-3 for fruits, and those of Cd varied within (15.4-895.2)×10-3 for leafy vegetables and (0.04-38.1)×10-3 for fruits, which signified that the average BFs of Pb and Cd for leafy vegetables was greater than those for fruit vegetables. (4) The correlations were not significant between the heavy metal content in vegetables and those in soils; however, total Pb and Cd in the edible parts of vegetables presented a higher significant correlation level (R2 =0.821; n =18, R20.01 =0.590). (5) The results of the risk assessment on vegetables indicated that the hazard quotient (HQ) for total Pb and Cd in the edible parts of leafy vegetables were 1.70 and 3.73, respectively, 34.00 times and 53.28 times higher than those of the fruits (0.005 and 0.070). In relation to suitability of agricultural products in this mining area, fruits were more suitable for planting than leafy vegetables. 参考文献 相似文献 引证文献

Metal Speciation and Contamination in Dredged Harbor Sediments from Kaohsiung Harbor, Taiwan

The status of metal speciation and contamination of sediments in Kaohsiung Harbor, Taiwan, was evaluated by a five-step sequential extraction procedure (exchangeable, carbonate, Fe–Mn oxides, organic matter, and residual). Eleven dredged sediment samples from various locations in the harbor were characterized in terms of heavy metals, grain size, and total organic carbons. Results showed that Hg, Pb, Cd, Cr, Cu, Zn, Ni, and Mn had different species composition patterns. The degree of sediment contamination was determined for an individual contamination factor (ICF) and a global contamination factor (GCF); results showed that Kaohsiung Harbor had a high potential risk for Pb, Cd, Cr, and Cu. Based on GCF values, the results showed that those stations, located in the vicinity of the river mouth, fish port, and industrial sites, contributed high potential risk to Kaohsiung Harbor. The potential risk of heavy metals to the environment was assessed for risk using the risk assessment code (RAC) and results showed that Pb, Cd, Zn, and Mn generally created a medium to high risk, and Hg, Cr, Cu, and Ni generally created a low to medium risk.

Spatial variation and contamination assessment of heavy metals in sediments in the Manwan Reservoir, Lancang River

Due to the construction and operation of Manwan Dam on the Lancang River, sediments were likely to deposit in the impoundment. In this research, sediment samples were collected from 17 sites in the whole reservoir in 2011 to investigate the distribution and sources of heavy metals (Al, As, Cu, Fe, Cd, Cr, Mn, Pb and Zn), as well as to assess the heavy metal contamination status. The results obtained using Principal Component Analysis (PCA) showed that the sources of heavy metals were mainly divided into two groups, natural factors and anthropogenic input. The anthropogenic inputs mainly came from industrial activities of the tributary rivers such as heavy metal mining and smelting, and agricultural practices such as fertilising and pesticide consumption. The sediment quality was assessed according to the sediment guidelines and the enrichment factor (EF). Concentrations of As, Cd, Cr, Cu, Pb and Zn in sediments at some of the sites exceeded either the Threshold Effects Level (TEL) of US National Oceanic and Atmospheric Administration (NOAA) or Effects Range-Low (ERL) of the Canadian Sediment Quality guidelines. The high levels of these heavy metals could cause adverse effects. One-way analysis of variance for spatial analysis revealed that no significant differences were found for most heavy metals at the tail, centre and head of the reservoir except that Cr showed significant differences (P<0.01) at the reservoir centre and the head. Significant variations for some heavy metals were observed in the tributaries and in the mainstream. The comparative EF indices suggested that As, Cd, Pb, Zn and Mn were slightly enriched and Cr, Fe and Cu were not enriched but had different “high–low” orders at the tail, centre and head of the reservoir. We depicted distribution map of enrichment factors for all heavy metals and the potential ecological risk index (RI) was applied to produce the comprehensive risk distribution map.

가막간 표층퇴적물 중의 금속 및 비금속 원소의 생지화확적 분포특성

In order to evaluate die geochemical characteristics of sediment in a semi-enclosed bay used as shellfish and fish farming area, the concentrations of metallic(V, Cr, Mn, Fe, Co. Ni, Cu, Zn, Ag, Cd, Hg, Ph, As) and non-metallic(P, Se) elements and uranium were measured in the surface sediment samples collected from 19 stations of Gamak Bay in April 2010. Metal contamination status in the sediments were also evaluated using the sediment quality guidelines(SQGs) proposed by the National Oceanic and Atmospheric Administration(NOAA) and the enrichment factor(EF). The concentrations of elements in sediment were mainly controlled by quartz-dilution effect(V, Cr, Fe, Co and Ni), the dilution effect of organic matter(Cd and U), and metal redistribution by the decomposition of organic matter(Mn, Ag, As, and Se). The concentrations of metals, except As and Ni, in sediments from all sampling stations were lower than ERL values of NOAA. Conclusively, the surface sediment of Gamak Bay was slightly polluted with Ni, Ag, Cd, and Cd but was not polluted with other elements on the basis of EF results. Our results suggest that the surface sediment in Gamak Bay is not polluted by metallic elements.

Status of Metal Contamination in Surface Waters of the Coastal Ocean off Los Angeles, California since the Implementation of the Clean Water Act

In order to establish the status of metal contamination in surface waters in the coastal ocean off Los Angeles, California, we determined their dissolved and particulate pools and compared them with levels reported in the 1970s prior the implementation of the Clean Water Act. These measurements revealed a significant reduction in particulate toxic metal concentrations in the last 33 years with decreases of ∼100-fold for Pb and ∼400-fold for Cu and Cd. Despite these reductions, the source of particulate metals appears to be primarily anthropogenic as enrichment factors were orders of magnitude above what is considered background crustal levels. Overall, dissolved trace metal concentrations in the Los Angeles coastal waters were remarkably low with values in the same range as those measured in a pristine coastal environment off Mexico's Baja California peninsula. In order to estimate the impact of metal contamination on regional phytoplankton, the internalization rate of trace metals in a locally isolated phytoplankton model organism (Synechococcus sp. CC9311) was also determined showing a rapid internalization (in the order of a few hours) for many trace metals (e.g., Ag, Cd, Cu, Pb) suggesting that those metals could potentially be incorporated into the local food webs.

Heavy metal contaminations in the groundwater of Brahmaputra flood plain: an assessment of water quality in Barpeta District, Assam (India)

A study was conducted to evaluate the heavy metal contamination status of groundwater in Brahmaputra flood plain Barpeta District, Assam, India. The Brahmaputra River flows from the southern part of the district and its many tributaries flow from north to south. Cd, Fe, Mn, Pb, and Zn are estimated by using atomic absorption spectrometer, Perkin Elmer AA 200. The quantity of heavy metals in drinking water should be checked time to time; as heavy metal accumulation will cause numerous problems to living being. Forty groundwater samples were collected mainly from tube wells from the flood plain area. As there is very little information available about the heavy metal contamination status in the heavily populated study area, the present work will help to be acquainted with the suitability of groundwater for drinking applications as well as it will enhance the database. The concentration of iron exceeds the WHO recommended levels of 0.3 mg/L in about 80% of the samples, manganese values exceed 0.4 mg/L in about 22.5% of the samples, and lead values also exceed limit in 22.5% of the samples. Cd is reported in only four sampling locations and three of them exceed the WHO permissible limit (0.003 mg/L). Zinc concentrations were found to be within the prescribed WHO limits. Therefore, pressing awareness is needed for the betterment of water quality; for the sake of safe drinking water. Statistical analysis of the data was carried out using Special Package for Social Sciences (SPSS 16).

Investigation of the Effects of Phosphate Fertilizer Application on the Heavy Metal Content in Agricultural Soils with Different Cultivation Patterns

The use of phosphate fertilizers is essential in agriculture, because they supply farmland with nutrients for growing plants. However, heavy metals might be included as impurities in natural materials and minerals, so heavy metals can also be present in phosphate fertilizers or other chemical fertilizers. The aim of this work was to assess the heavy metal content and contamination status of agricultural soils in the Hamadan province of Iran used for the cultivation of different crops, including cucumber, potatoes, and sugar beet. Surface soil samples were collected and analyzed to determine the total concentration of specific elements (As, Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn), before the pollution index was calculated for each element. Soils used for the cultivation of the three types of crop were not contaminated with As, Cr, Cu, Pb, or Zn. However, the pollution indices for Cd were 1.1, 4.4, and 3.8 in cucumber, potato, and sugar beet fields, respectively, which indicated moderate, high, and high levels of contamination, respectively. Soils from potato and sugar beet fields were heavily contaminated with Cd, which may have resulted from long-term overuse of phosphate fertilizers.

Concentration, enrichment and distribution of heavy metals in surface sediments of the Tangier Bay, Morocco

The distribution, enrichment, and accumulation of heavy metals in the surface sediments of the Tangier Bay, Morocco, were investigated. Surface sediment samples from eleven locations in the Bay of Tangier were collected in 2007 and characterized for grain size, organic matter and metal content (e.g. Fe, Mn, Cr, Cu, Ni, Pb, Zn and Cd). The evaluation of the heavy metal contamination status of the bay showed minor enrichment by the enrichment factors (EF) calculation, corroborated by the metal pollution index (MPI). The results of a Pearson correlation showed high positive correlations among organic carbon and most metals (0.788 < r < 0.939) and cluster analysis grouped the stations inside the harbour (stations 1, 10 and 9) and in the vicinity of the principal rivers in the bay (stations 3 and 11), which showed the highest concentrations of metal content. The main sources of contamination are domestic and industrial effluents, which arise due to the lack of sewage treatment. However, these areas could not be classified as polluted when the data were compared with sediment quality guidelines (USEPA, 1997).

Hepatic metallothionein concentrations in the golden grey mullet ( Liza aurata) – Relationship with environmental metal concentrations in a metal-contaminated coastal system in Portugal

This field survey was designed to assess the environmental metal contamination status of Ria de Aveiro (Portugal). To achieve that goal, the concentrations of Cd, Hg, Cu and Zn in the sediments and water were assessed and Liza aurata hepatic metallothionein (MT) determined. The relationships between MT and environmental metal concentrations and hydrological factors were examined. Results revealed a wide distribution of metals both in water and sediments throughout the lagoon, mainly at Rio Novo do Principe (RIO) and Laranjo (LAR), at concentrations that may affect biota. MT concentrations were higher at the sites with high metal content (RIO and LAR). A significant positive correlation was found between MT and Cd in the sediments as well as with MT and Hg and Cu in the water. Moreover, a negative correlation between MT and salinity was found. Thus, the current data support MT use as a biomarker of metal exposure emphasizing the importance of hydrological parameters in its concentrations. Results suggest the continued monitoring of this lagoon system.

Distribution and contamination of trace metals in surface sediments of the East China Sea

The distributions, contamination status and annual sedimentation flux of trace metals in surface sediments of the East China Sea (ECS) were studied. Higher concentrations of the studied metals were generally found in the inner shelf and the concentrations decreased seaward. The sequences of the enrichment factor (EF) of the studied metals are Cu > Mn > Ni > Zn > Pb > Fe. The values of EF suggest that the metals contamination in the middle and outer shelves of the ECS is still minor. The annual sedimentation fluxes of trace metals in the ECS were: Fe, 3.48 × 10 7 t/y; Mn, 9.07 × 10 5 t/y; Zn, 1.08 × 10 5 t/y; Ni, 4.48 × 10 4 t/y; Pb, 4.32 × 10 4 t/y and Cu, 3.1 × 10 4 t/y, respectively. Approximately 55–70% and 10–17% of the sedimentation fluxes of trace metals were deposited in the inner shelf and the Changjiang estuarine zone.

Heavy metal accumulation in different varieties of wheat ( Triticum aestivum L.) grown in soil amended with domestic sewage sludge

The concentrations of heavy metals (HMs) in plants served to indicate the metal contamination status of the site, and also revealed the abilities of various plant species to take up and accumulate them from the soil dressed with sewage sludge. A study to comprehend the mobility and transport of HMs from soil and soil amended with untreated sewage sludge to different newly breaded varieties of wheat (Anmol, TJ-83, Abadgar and Mehran-89) in Pakistan. A pot-culture experiment was conducted to study the transfer of HMs to wheat grains, grown in soil (control) and soil amended with sewage sludge (test samples). The total and ethylenediaminetetraaceticacid (EDTA)-extractable HMs in agricultural soil and soil amended with domestic sewage sludge (SDWS) and wheat grains were analysed by flame atomic absorption spectrometer/electrothermal atomic absorption spectrometer, prior to microwave-assisted wet acid digestion method. The edible part of wheat plants (grains) from test samples presented high concentration of all HMs understudy (mg kg −1). Significant correlations were found between metals in exchangeable fractions of soil and SDWS, with total metals in control and test samples of wheat grains. The bio-concentration factors of all HMs were high in grains of two wheat varieties, TJ-83 and Mehran-89, as compared to other varieties, Anmol and Abadgar grown in the same agricultural plots.

Accumulated Heavy Metal Content in Wolf Spider, Pardosa astrigera (Araneae: Lycosidae), as a Bioindicator of Exposure

To investigate the rate and extent of heavy metal accumulation in a potential indicator species of wolf spider, Pardosa astrigera (L. Koch) (Araneae: Lycosidae), adult spiders were exposed to three different heavy metals by dietary uptake. The spiders were regularly fed with heavy metal-coated fruit flies (20 mM CdCl 2, 10 mM PbCl 2, 10 mM HgCl 2; singly or altogether) up to 8 weeks, and the heavy metal contents in individual spiders were analyzed. Accumulation pattern of individual heavy metal in P. astrigera body was significantly different. Both Pb and Hg reached the accumulation saturation point (ca. 3-4 ug/spider) in a relatively short period of exposure (two weeks). In contrast, the Cd accumulation gradually increased up to 6 weeks and then arrived at the saturation point (ca. 10 μg/spider). These findings indicate that the spider is more selective in the Cd accumulation compared to Pb and Hg. Similar patterns of individual heavy metal accumulation were also observed in the exposure to complex heavy metals, where the accumulation capacity for Cd was most significant. The contents of Cd and Pb in the P. astrigera collected from the down-stream area of Sin-gil stream were ca. 1.2 and 1.6 μg/spider, lower than the saturation level, but well reflecting the heavy metal contamination status of the area. The Cd accumulation in P. astrigera was also confirmed by histo-chemical staining of Cd with QAI [2-(8-quinolylazo)-4, 5-diphenylimidazol], in which vacuole-like complexes containing Cd were intensely stained in the hepatopancreatic tissue of the 20 mM CdCl 2-exposed spider. No mortality was observed during the time course of heavy metal exposure but the development of P. astrigera both in nymphal and sub-adult stages was suppressed by the constant exposure to 20 mM CdCl 2 as judged by the reduced rate of body weight gain, suggestive of its apparent sub-lethal effects.

Primary investigation of heavy metal contamination status in molluscs collected from Chinese coastal sites.

Primary investigation of heavy metal contamination status in molluscs collected from Chinese coastal sites.

Soil Contamination and Plant Uptake of Heavy Metals at Polluted Sites in China

We investigated heavy metal contamination in soils and plants at polluted sites in China including some with heavy industries, metal mining, smelting and untreated wastewater irrigation areas. We report our main findings in this paper. The concentrations of heavy metals, including Cd and Zn, in the soils at the investigated sites were above the background levels, and generally exceeded the Government guidelines for metals in soil. The concentrations of metals in plants served to indicate the metal contamination status of the site, and also revealed the abilities of various plant species to take up and accumulate the metals from the soil. Substantial differences in the accumulation of heavy metals were observed among the plant species investigated. Polygonum hydropiper growing on contaminated soils in a sewage pond had accumulated 1061 mg kg−1 of Zn in its shoots. Rumex acetosa L. growing near a smelter had accumulated more than 900 mg kg−1 of Zn both in its shoots and roots. Therefore these species have potential for phytoremediation of metal-contaminated sites. Our results indicate the need to elucidate the dynamics of soil metal contamination of plants and the onward movement of metal contaminants into the food chain. Also our results indicate that the consumption of rice grown in paddy soils contaminated with Cd, Cr or Zn may pose a serious risk to human health, because from 24 to 22% of the total metal content in the rice biomass was concentrated in the rice grain. Platanus acerifolia growing on heavily contaminated soil accumulated only very low levels of heavy metals, and this mechanism for excluding metal uptake may have value in crop improvement. Sources of metal entering the environmental matrices studied included untreated wastewater, tailings or slurries and dust depositions from metal ore mining, and sewage sludge. Pb, Zn or Cd concentrations declined with the distance from metal smelter in accordance with a good exponential correlation (R 2 >0.9), and this shows that metal dust deposition is an important contributor to metal contamination of soils.

Variation of nutrient and metal concentrations in aquatic macrophytes along the Rio Cachoeira in Bahia (Brazil)

The use of cuprous fungicides in cocoa production in the southern part of the state of Bahia (Brazil) for decades has caused an accumulation of copper in various components of the cocoa plantations, and a contamination of regional freshwater ecosystems is suspected. Urban and industrial sources are supposed to contribute to water pollution and eutrophication of the Rio Cachoeira, the main river in this region. In order to study the metal contamination and nutritional status of this freshwater ecosystem, samples of the aquatic macrophytes Eichhornia crassipes and Pistia stratiotes were collected at seven sites along the river course. The samples were analysed for their copper, aluminium, chromium, nitrogen and phosphorus concentrations. The levels of heavy metals increased in the downstream direction, particularly in the roots of water hyacinth. A dramatic increase of nitrogen and phosphorus concentrations in water as well as in plant tissues was found in samples collected downstream from the city of Itabuna. Metal input and eutrophication were attributed to agricultural, industrial and urban sources in the region. Biomonitoring of the water quality using aquatic macrophytes as accumulative indicator plants is recommended in addition to chemical water analyses.