Trace Metal Contents (Al, Cu and Zn) of Tea: Tea and Soil from Two Tea Plantations, and Tea Products from Different Provinces of China

The present project aims to investigate the possible contamination of teas with the trace metals: Al, Cu and Zn. Tea bushes sampled from two tea plantations in the northern part of Guangdong Province accumulated higher concentrations of Cu and Zn in young leaves, and of Al in old leaves. The analysis of the three metals in tea produced in different provinces indicated higher Al levels in those obtained from Guangdong and Yunnan Provinces, which may be due to the lower soil pH in these areas. Green tea had the lowest Al concentration among the four types of tea studied, as only the bud and two young leaves are used, whereas older leaves are used for other types of tea (black, Oolong and Puerh tea). The transfer of Al, Cu and Zn from soil to different parts of tea bushes was low in general, except for Zn at Lechang tea plantation which next to a Pb/Zn mine, where a higher transfer was observed from young leaves to tea products, indicating possible metal contamination during tea processing. However, low concentrations of Cu and Zn (less than 0.07 mg Cu L^-1 and 0.17 mg Zn L^-1), and moderate amounts of Al (2.1-2.5 mg L^-1) were obtained in the tea liquor (1% hot water extracts).     

Heavy metal pollution in soil and plants at bone char site

This study determined the heavy metal concentration in soil and plants at a bone char site in Umuahia, Nigeria. Soil and plant samples collected in a randomized complete block design (RCBD) were analyzed for zinc (Zn), lead (Pb), cadmium (Cd), nickel (Ni), and arsenic (As). The concentration of metals in soil and plants in the vicinity of the bone char site are as follows: Zn (172?mg?kg^?1) and Ni (0.62?mg?kg^?1) in soil were highest at site P₃, Pb (2.37?mg?kg^?1) and As (0.08?mg?kg^?1) at site P₁, and Cd (18.30?mg?kg^?1) at site P₂. In plants, the concentrations of Zn (41.17?mg?kg^?1) and Cd (3?mg?kg^?1) were highest in Albizia ferruginea, Ni in Dialium guineense (0.09?mg?kg^?1), while Pb was in D. guineense (0.08?mg?kg^?1) and Spathodea companulata (0.06?mg?kg^?1). The levels of Zn, Cd, Pb, Ni, and As in soil ranged from 11.2 to 172, 2.68 to 18.2, 0.026 to 2.37, 0.33 to 0.62, and 0.02 to 0.08?mg?kg^?1, respectively. In plants, the concentration of Zn, Cd, Pb, and Ni ranged from 2.01 to 41.17, 0.12 to 3, 0.02 to 0.08, and 0.03 to 0.09?mg?kg^?1, respectively. There were significant correlations between Zn and Cd, and Pb and As in soil. The high concentration of Cd in soil might affect soil productivity.     

Heavy metal concentration in soil and woody plants in a quarry

This study determined the concentration of three heavy metals zinc (Zn), lead (Pb), and cadmium (Cd) in soil and in a woody plant species, Milicia excelsa, at Ishiagu quarry, Nigeria. The highest soil concentrations of Zn, Pb, and Cd in soil were obtained at 1?m from the quarry site. In M. excelsa, the highest concentrations of Zn, Pb, and Cd were 3.12–9.1, 3.9–6.01, and 0.51–1.12?mg?kg^?1, respectively. There were significant positive correlations between Cd and Zn (r?=?0.963) and Cd and Pb (r?=?0.974) in plants as well as between Cd and Pb (r?=?9.84) in soil. The level of Cd in soil reflected significant pollution compared to average global concentrations in soils.     

EDTA and citric acid mediated phytoextraction of Zn, Cu, Pb and Cd through marigold (Tagetes erecta)

Phytoextraction is an emerging cost-effective solution for remediation of contaminated soils which involves the removal of toxins, especially heavy metals and metalloids, by the roots of the plants with subsequent transport to aerial plant organs. The aim of the present investigation is to study the effects of EDTA and citric acid on accumulation potential of marigold (Tagetes erecta) to Zn, Cu, Pb, and Cd and also to evaluate the impacts of these chelators (EDTA and citric acid) in combination with all the four heavy metals on the growth of marigold. The plants were grown in pots and treated with Zn (7.3 mg l(-1)), Cu (7.5 mg I(-1)), Pb (3.7 mg l(-1)) and Cd (0.2 mg l(-1)) alone and in combination with different doses of EDTA i.e., 10, 20 and 30 mg l(-1). All the three doses of EDTA i.e., 10, 20 and 30 mg l(-1) significantly increased the accumulation of Zn, Cu, Pb and Cd by roots, stems and leaves as compared to control treatments. The 30 mg l(-1) concentration of citric acid showed reduced accumulation of these metals by root, stem and leaves as compared to lower doses i.e., 10 and 20 mg l(-1). Among the four heavy metals, Zn accumulated in the great amount (526.34 mg kg(-1) DW) followed by Cu (443.14 mg kg(-1) DW), Pb (393.16 mg kg(-1) DW) and Cd (333.62 mg kg(-1) DW) in leaves with 30 mg l(-1) EDTA treatment. The highest concentration of EDTA and citric acid (30 mg l(-1)) caused significant reduction in growth of marigold in terms of plant height, fresh weight of plant, total chlorophyll, carbohydrate content and protein content. Thus EDTA and citric acid efficiently increased the phytoextractability of marigold which can be used to remediate the soil contaminated with these metals.     

Organic acid profile and phenolic and sugar content in Salix purpurea × viminalis L. cultivated with different spent mushroom substrate and copper additions

The aim of the study was to determine the response of Salix purpurea?×?viminalis L. growing on Pleurotus ostreatus spent mushroom substrate (SMS) with different copper (Cu) addition. The content of Cu in roots, leaves and shoots was reduced by SMS addition. A decrease of biomass was observed with simultaneous Cu concentration increase. SMS induced leaf and root elongation of Cu-treated plants. Variation in the profile of low molecular weight organic acids with the domination of oxalic and acetic acids was observed. The total phenolic content significantly increased for plants cultivated with SMS, while the biosynthesis of salicylic acid was considerably weakened. The content of sugars was generally reduced by SMS. Alteration in the level of the stress-related molecules suggests mitigation of the harmful effect of Cu on Salix hybrid metabolism by SMS addition. This pointed to the possibility of using SMS in contaminated soil to reduce the toxic effect of metals on plants used in phytoextraction.     

Trace metal contents ofTaraxacum officinale (dandelion) as a convenient environmental indicator

Some vascular plants are known to concentrate trace metals and are regarded to be suitable indicators of atmospheric metal deposition. Among plant species used for biogeochemical studies dandelion (Taraxacum officinale.) is convenient for monitoring air/soil pollution. The plant commonly occurs in different ecosystems with relatively parallel stages of ontogenesis over a broad area of geographical regions. Its leaves and roots are easily accessible for sampling. Leaf to root ratios of metal concentrations in dandelion may indicate the source of metals during the growing season. Trace metals in leaves and roots of dandelion from 132 sites in Poland showed higher concentrations in the plants from the SW region compared to those from the NE region of the country. However, the differences were only statistically significant ( = 0.05) for Cd, Ni, and Pb. Geometric means of metal concentrations (mg kg^–1, air dried weight) in dandelion leaves of the SW and NE regions were: Cd 0.85, 0.52; Cr 0.99, 0.81; Cu 11.2, 11.1; Fe 184.4, 100.0; Mn 59.7, 51.4; Ni 2.1, 1.5; Pb 4.4, 3.0; and Zn 49.6, 41.3, respectively. Markedly higher concentrations of Cd, Pb, and Zn were found in the leaves of the dandelion over roots in the SW region. These metals are the most serious aerial pollutants in that part of the country.     

Measurement of metal bioaccessibility in vegetables to improve human exposure assessments: field study of soil–plant–atmosphere transfers in urban areas,South China

The quality of cultivated consumed vegetables in relation to environmental pollution is a crucial issue for urban and peri-urban areas, which host the majority of people at the global scale. In order to evaluate the fate of metals in urban soil–plant–atmosphere systems and their consequences on human exposure, a field study was conducted at two different sites near a waste incinerator (site A) and a highway (site B). Metal concentrations were measured in the soil, settled atmospheric particulate matter (PM) and vegetables. A risk assessment was performed using both total and bioaccessible metal concentrations in vegetables. Total metal concentrations in PM were (mg kg^?1): (site A) 417 Cr, 354 Cu, 931 Zn, 6.3 Cd and 168 Pb; (site B) 145 Cr, 444 Cu, 3289 Zn, 2.9 Cd and 396 Pb. Several total soil Cd and Pb concentrations exceeded China’s Environmental Quality Standards. At both sites, there was significant metal enrichment from the atmosphere to the leafy vegetables (correlation between Pb concentrations in PM and leaves: r = 0.52, p < 0.05) which depended on the plant species. Total Cr, Cd and Pb concentrations in vegetables were therefore above or just under the maximum limit levels for foodstuffs according to Chinese and European Commission regulations. High metal bioaccessibility in the vegetables (60–79 %, with maximum value for Cd) was also observed. The bioaccessible hazard index was only above 1 for site B, due to moderate Pb and Cd pollution from the highway. In contrast, site A was considered as relatively safe for urban agriculture.     

Temporal variation of metals in the seagrass Posidonia australis and its potential as a sentinel accumulator near a lead smelter

Temporal variation in the concentrations of Cd, Cu, Mn, Ni, Pb and Zn in leaves of the seagrass Posidonia australis was studied at three sites near a lead smelter on the shore of Spencer Gulf, a large hypersaline marine embayment in South Australia, on four occasions from October 1980 to September 1981. Concentrations of Cd, Mn, Pb and Zn of up to 541, 537, 379 and 4241 g g^-1, respectively, were found in leaves collected from the site nearest to the smelter. A substantial temporal variation in the concentrations of these metals in samples from all sites resulted from the combined effect of leaf age and collection strategy. Concentrations of Cd, Cu and Zn in the leaf epibiota were lower than those in the leaves, but the reverse was true for Mn and Ni. The use of seagrass leaves as sentinel accumulators for Cd, Pb and Zn must be based on collections made at the same time of year, or otherwise account for the effect of leaf age on concentrations of the metals in the samples.     

Bioavailability of trace metals in brownfield soils in an urban area in the UK

Thirty-two brownfield sites from the city of Wolverhampton were selected from those with a former industrial use, wasteland or areas adjacent to industrial processes. Samples (<2 mm powdered soil fraction) were analysed, using inductively coupled plasma–atomic emission spectrometry (ICP–AES) for 20 elements. Loss on ignition and pH were also determined. A five-step chemical sequential extraction technique was carried out. Single leach extraction with 0.12 M hydrochloric acid of Pb, Cu and Zn in soil was determined as a first approximation of the bioavailability in the human stomach. Some of the sites were found to have high concentrations of the potentially toxic elements Pb, Zn, Cu and Ni. The partitioning of metals showed a high variability, however a number of trends were determined. The majority of Zn was partitioned into the least chemically stable phases (steps 1, 2 and 3). The majority of Cu was associated with the organic phase (step 4) and the majority of Ni was fractionated into the residue phase (step 5). The majority of Pb was associated with the residue fraction (step 5) followed by Fe–Mn oxide fraction (step 3). The variability reflects the heterogeneous and complex nature of metal speciation in urban soils with varied historic histories. There was a strong inverse linear relationship between the metals Ni, Zn and Pb in the readily exchangeable phase (step 1) and soil pH, significant at P < 0.01 level. There was a significant increase (P < 0.05) in the partitioning of Cu, Ni and Zn into step 4 (the organic phase) in soils with a higher organic carbon content (estimated by loss on ignition). Copper was highly partitioned into step 4 as it has a strong association with organics in soil but this phase was not important for the partitioning of Ni or Zn. The fractionation of Ni, Cu and Zn increased significantly in step 3 when the total metal concentration increases (P < 0.01). The Fe–Mn oxide fraction becomes more important in soils elevated in these metals, possibly due to the scavenging of metals by oxides. Cu and Pb extracted by HCl was statistically similar to the sum of the metals in steps 1 to 4 (P < 0.01) and HCl available Zn was statistically similar to the sum of Zn in steps 1 to 3 (P < 0.01). Step 4 (the organic phase) was not an important phase for Zn, so it was concluded that any Cu, Zn and Pb present in soil in a nonresidue phase would be potentially available for uptake into the human system once soil has been ingested.     

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.     

Determination of the levels of selected metals in seeds,flowers and fruits of medicinal plants used for tapeworm treatment in Ethiopia

The level of accumulation of selected essential and non-essential metals, namely; Ca, Cu, Fe, Zn, Mn, Cd, Pb, and Cr have been investigated in the seeds, fruits, and flowers of some medicinal plants utilized for tapeworm treatment in Ethiopia and their respective soil samples. These include seed of Cucurbita maxima (Duba), fruit of Embelia abyssinica (Ankoko), flowers of Hagenia abyssinica (Kosso), and fruits of Rosa abyssinica (Kega) and their respective soil samples. A wet digestion procedure with a mixture of conc. HNO₃ and HClO₄ for the plant samples and a mixture of conc. HNO₃, HCl, and H₂O₂ for soil samples were used to solubilize the metals. Ca (1280–12,670?mg?kg^?1) was the predominant metal followed by Fe (104–420?mg?kg^?1), and Zn (18–185?mg?kg^?1) in all the plant materials except for Hagenia abyssinica flower from Hirna in which Mn (16–42?mg?kg^?1) followed by Fe. Among the non-essential toxic metals, Pb was not detected in Cucurbita maxima of Boji, Gedo and Hirna origins and in Rosa abyssinica of Hirna site. Similarly, Cr was not detected in Rosa abyssinica fruits of Boji and Gedo sites. The sampled soils were found to be between strongly acidic to weakly basic (pH: 4.7–7.1). In the soil samples, Ca (8528–18,900?mg?kg^?1) was the most abundant metal followed by Fe (417–912?mg?kg^?1), Zn (155–588?mg?kg^?1), Mn (54–220?mg?kg^?1), Cr (21–105. mg?kg^?1), Cu (11–58?mg?kg^?1), Pb (13–32?mg?kg^?1) and Cd (2.8–4.8?mg?kg^?1). The levels of most of the metals determined in the medicinal plants and the respective soil samples are in good agreement with those reported in the literature and the standards set for the soil by various legislative authorities.     

Assessment of As and Heavy Metal Contamination in the Vicinity of Duckum Au-Ag Mine, Korea

In order to assess the potential of As and heavy metal contamination derived from past mining activity and to estimate the human bioavailability quotients for As and heavy metals. Tailings, soils and crop samples were collected and analysed for As, Cd, Cu, Pb and Zn. The mean concentrations of As, Cd, Cu, Pb and Zn in the tailings were 68.5, 7.8, 99, 3,754 and 733 µg g^–1, respectively. Maximum Pb concentration in tailings was up to 90 times higher than its tolerable level. The concentrations of these metals were highest in the soils from the dressing plant area, and decreased in the order: farmland soil to paddy soil. In particular, some of the soils from the dressing plant area contained more than 1% of Pb and Zn. The pollution index ranged from 0.19 to 1.93 in paddy soils, and from 1.47 to 3.60 in farmland soils. The average concentrations of heavy metals in crops collected from farmland were higher than those in rice stalks or rice grains, and higher than the internationally accepted limits for vegetables. Element concentrations extracted from farmland soils within the simulated human stomach for 1 h are 9.4 mg kg^–1 As, 3.8 mg kg^–1 Cd, 37 mg kg^–1 Cu, 250 mg kg^–1 Pb and 301 mg kg^–1 Zn. In particular, the extracted concentrations of Cd, Pb and Zn are in excess of the tolerable levels. The results of the simple bioavailability extraction test (SBET) indicate that regular ingestion (by inhalation and from dirty hands) of soils by the local population could pose a potential health threat due to long-term toxic element exposure.     

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.     

Assessment of metals in soil extracts and their uptake and movement within Tamarix nilotica at Lake Nasser banks,Egypt

This study aims to determine heavy-metal levels in soil from the banks of Lake Nasser, the ability of Tamarix nilotica to accumulate such metals from soil and hence its potential for phytoextraction. Soil and Tamarix samples were collected from the banks of four bights around Lake Nasser and analysed for Fe, Mn, Ca, Mg, Cr, Cu, Ni, Zn, Cd and Pb by atomic absorption spectrometry, whereas Na and K were measured by atomic emission spectrophotometry. Three different methods of extraction were used for the soil samples. Lead, copper and zinc were equally distributed between the exchangeable phase and Fe/Mn oxide-bound form, while other measured metals were mainly present in the Fe/Mn oxide fraction. With the exception of iron, all metals studied showed total concentrations within the geochemical background values. T. nilotica exhibited elevated concentrations of Na (36.2–48.5?mg?g^?1) and K (2.74–4.33?mg?g^?1) in stems, and relatively high concentrations of Pb, Cd and Co (0.39–1.03?µg?g^?1, 0.24–1.3?µg?g^?1 and 1.94–5.3?µg?g^?1, respectively) are found in plant leaves. Bioaccumulation factors of Na and K (9.3 and 12.63, respectively) were high in T. nilotica stems. While the bioaccumulation of Pb, Cd, Co and Ni (2870.1, 2035.4, 10.5 and 5313.2, respectively) was high in plant leaves, Fe, Mn, Ca and Mg were accumulated relatively equally in plant stems and leaves. T. nilotica was found to secrete high amounts of Na, Ca and K, in addition to small amounts of all accumulated metals except Cd and Cu. These secreted metals appeared as salt crystals (67.5% Na; 25.8% Ca; 5% Mg; 1.5% K and 0.16% trace and minor elements) on the plant surface. The concentrations of all the metals studied in T. nilotica were higher than in the salt crystals. Statistical analysis of the database suggests bioaccumulation of these metals from soil to T. nilotica. This reflects the importance of using T. nilotica as a model in the phytoremediation process as an established environmental clean-up technology.     

Concentrations of cadmium,manganese, copper,zinc, and lead in the tissues of the oyster (Crassostrea iredalei) obtained from Setiu Lagoon,Terengganu, Malaysia

Heavy metals pollution in aquatic environments is a major problem contributing to human health issues. The study of these pollutants through bioindicators such as the oyster Crassostrea iredalei is important for (1) determining the levels and sources and (2) regulating the quantity of pollutants. The concentrations of cadmium (Cd), manganese (Mn), copper (Cu), zinc (Zn), and lead (Pb) in tissues of C. iredalei, sediment and surrounding water was measured, and data was analyzed to determine the relationship between sampling periods and between oyster tissue, sediment, and water. The highest concentration of metals in oyster tissue was Zn, followed by Cu, Mn, Cd, and Pb. Concentrations of Cd, Cu, and Zn exceeded the maximum level allowed according to the Malaysian Food Act of 1983, which is equivalent to the WHO recommended levels of heavy metals in organisms used for consumption. The highest metal concentration in sediment was Mn followed by Zn, Pb, Cu, and Cd. Concentrations of heavy metals in surrounding water were Zn, Pb, Cu, Mn, and Cd. There was no correlation between metal concentration in oyster tissue and in sediment for all five metals.     

多种盐分离子作用下苋菜对重金属的吸收累积特征

模拟不同淋洗脱盐阶段滩涂土壤孔隙水中盐分和重金属含量,通过苋菜水培试验,研究多种盐分离子（SO42-、Cl-、NO3-、CO32-、Na＋、Ca2＋、K＋和Mg2＋等）的共同作用下,苋菜对Zn、Cu、Ni、Cr、Pb和Cd 6种重金属的吸收、累积和转运的变化。结果表明,与对照相比,在不同盐分离子浓度影响下,苋菜茎叶中Cd的累积增幅为69.2%～146.2%,而茎叶中其他重金属的含量无显著变化,苋菜根系中Cd、Pb、Cr、Ni和Cu含量的最大增幅分别为187.8%、197.7%、305.7%、228.1%和58.2%,但根系中Zn含量未受到显著影响。在相对较高的盐分离子浓度（〉1 312.4 mg.L-1）范围内,不同盐分离子浓度处理间苋菜茎叶和根系中6种重金属含量差异均不显著。盐分处理显著降低了苋菜对Pb、Cr、Ni和Cu的转移系数,但未显著影响苋菜对Cd和Zn的转移系数。     

电子废物不当处置的重金属污染及其环境风险评价 Ⅴ. 电子废物焚烧迹地土壤金属污染对土壤微生物生物量和土壤呼吸的影响

在广东省清远市龙塘镇电子废物焚烧区附近分别设置了主要受电子废物焚烧造成的重金属近距离沉降影响的污染区(U)和距离焚烧活动核心区约1km的水平迁移污染区(L),并在焚烧活动核心区非主风向一侧山丘的反向坡地设置了对照区(CK),探讨了不同程度的重金属污染对土壤微生物生物量碳(MBC)和土壤呼吸(SR)的影响.结果表明,土壤Cu、Pb、Cd的含量平均值均呈U区>L区>CK区,在污染严重的U区,Cu、Pb、Cd、Ni、Cr和Zn的含量平均值分别是对照区的52.2倍、5.1倍、3.2倍、2.1倍、1.9倍和1.5倍.相应地,U区土壤MBC、土壤基础呼吸(BR)和基质诱导呼吸(SIR)的平均值分别只有对照区的48.0%、28.4%和15.3%,而在污染程度相对较轻的L区则分别为对照区的97.0%、70.1%和60.7%.土壤MBC和SIR均与土壤中Zn、Cu、Pb含量呈极显著负相关(p<0.01).以上结果表明,土壤微生物的生长和土壤生物活性受到了电子废物焚烧排放物(特别是重金属)生物毒性的严重影响,土壤SIR是响应最为敏感的指标.     

城市道路旁小蜡叶片对重金属的富集特征

通过对合肥市市区交通干线、城郊公路和植物园道路(对照区)的土壤,以及道路绿化灌木小蜡(Ligustrum sinense)叶片中Cu,Zn,Pb,Cd和Cr含量的测定,分析城市交通产生的大气重金属污染物在土壤和植物叶片中的富集特征.结果表明,公路交通和车辆尾气排放产生的重金属污染物能够显著地在土壤和小蜡叶片中富集.公路土壤中富集的Cu,Zn,Pb和Cr之间有着较高的相关性,且富集量与道路车流量有着明显的正相关.小蜡叶片富集的Cu,Zn,Pb,Cd和Cr主要来自于道路交通产生的大气重金属污染物,同土壤中相应重金属元素的相关性较差,而且市区干线的叶片富集量高于城郊公路,城郊公路高于对照点.雨水的冲刷能够减少小蜡叶片表面重金属的含量,同时小蜡叶片对重金属的富集,在4月至7月的富集速度或富集增量高于7月至10月,这与小蜡叶片的生长趋势相一致.     

Biosolids application affects the competitive sorption and lability of cadmium,copper, nickel,lead, and zinc in fluvial and calcareous soils

The objective of this research was to investigate the effects of biosolids on the competitive sorption and lability of the sorbed Cd, Cu, Ni, Pb, and Zn in fluvial and calcareous soils. Competitive sorption isotherms were developed, and the lability of these metals was estimated by DTPA extraction following their sorption. Sorption of all metals was higher in the fluvial than in the calcareous soil. Sorption of Cu and Pb was stronger than that of Cd, Ni, and Zn in all soils. Biosolids application (2.5%) reduced the sorption of all metals especially Cu and Pb (28–43%) in both soils (especially the calcareous soil) at the lower added metal concentrations (50 and 100 mg L^?1). However, it increased the sorption of all metals especially Pb and Cu in both soils (especially the calcareous soil; 15.5-fold for Cu) at the higher added concentrations (250 and 300 mg L^?1). Nickel showed the highest lability followed by Cd, Zn, and Pb in both soils. Biosolids increased the lability of the sorbed Ni in the fluvial soils at all added concentrations and the lability of Cd, Pb, and Zn at 50 mg L^?1, but decreased the lability of Cd, Pb, and Zn at 250 and 300 mg L^?1 in both soils. We conclude that at low loading rate (e.g., 50 mg L^?1) biosolids treatment might increase the lability and environmental risk of Cd, Cu, Pb, and Zn. However, at high loading rate (e.g., 300 mg L^?1) biosolids may be used as an immobilizing agent for Cd, Cu, Pb, Zn and mobilizing agent for Ni.     

铅锌冶炼厂土壤污染及重金属富集植物的研究

对株洲市铅锌冶炼厂生产区进行了植被和土壤调查。结果表明，该厂土壤污染以镉铅锌(Cd、Pb、Zn)最为严重，尤其是重金属镉在土壤中含量超过背景值高达208倍，分析原因主要是由于大气尘降和雨水淋洗等使得污染加重。实验采集并分析测定了9种植物中重金属富集量，首次报道了土荆芥是一种铅超富集植物，其体内Pb质量分数高达3888mg／kg。另一种植物商陆能大量富集镉，具有地下部向地上部转运能力强、生物量大、富集总量高的特点，有很大研究价值和应用潜力。另外，荨麻对Zn有较强富集能力，这3种植物可分别用于铅、镉和锌等3种重金属污染土壤的植物修复。