Analysis of transgenic Indian mustard plants for phytoremediation of metal-contaminated mine tailings

Transgenic Indian mustard [Brassica juncea (L.) Czern.] plants overproducing the enzymes gamma-glutamylcysteine synthetase (ECS) or glutathione synthetase (GS) were shown previously to have increased levels of the metal-binding thiol peptides phytochelatins and glutathione, and enhanced Cd tolerance and accumulation. Furthermore, transgenic Indian mustard plants overexpressing adenosine triphosphate sulfurylase (APS) were shown to have higher levels of glutathione and total thiols. These results were obtained with a solution culture. To better examine the phytoremediation potential of these transgenics, a greenhouse experiment was performed in which the transgenics were grown on metal-contaminated soil collected from a USEPA Superfund site near Leadville, Colorado. A grass mixture used for revegetation of the site was included for comparison. The ECS and GS transgenics accumulated significantly (P < 0.05) more metal in their shoot than wild-type (WT) Indian mustard, while the APS plants did not. Of the six metals tested, the ECS and GS transgenics accumulated 1.5-fold more Cd, and 1.5- to 2-fold more Zn, compared with wild-type Indian mustard. Furthermore, the ECS transgenics accumulated 2.4- to 3-fold more Cr, Cu, and Pb, relative to WT. The grass mixture accumulated significantly less metal than Indian mustard: approximately 2-fold less Cd, Cu, Mn, and Zn, and 5.7-fold less Pb than WT Indian mustard. All transgenics removed significantly more metal from the soil compared with WT Indian mustard or an unplanted control. While WT did not remove more metal than the unplanted control for any of the metals tested, all three types of transgenics significantly reduced the soil metal concentration, and removed between 6% (Zn) and 25% (Cd) of the soil metal. This study is the first to demonstrate enhanced phytoextraction potential of transgenic plants using polluted environmental soil. The results confirm the importance of metal-binding peptides for plant metal accumulation and show that results from hydroponic systems have value as an indicator for phytoremediation potential.     

Constitutive expression of a high-affinity sulfate transporter in Indian mustard affects metal tolerance and accumulation

The Stylosanthes hamata SHST1 gene encodes a high-affinity sulfate transporter located in the plasma membrane. In this study the S. hamata SHST1 gene was constitutively expressed in Indian mustard [Brassica juncea (L.) Czern.] to investigate its importance for tolerance and accumulation of various oxyanions that may be transported by SHST1 and for cadmium, which is detoxified by sulfur-rich compounds. The transgenic SHST1 lines SHST1-12C and SHST1-4C were compared with wild-type Indian mustard for tolerance and accumulation of arsenate, chromate, tungstate, vanadate, and cadmium. As seedlings the SHST1 plants accumulated significantly more Cd and W, and somewhat more Cr and V. The SHST1 seedlings were less tolerant to Cd, Mo, and V compared to wild-type plants. Mature SHST1 plants were less tolerant than wild-type plants to Cd and Cr. SHST1 plants accumulated significantly more Cd, Cr, and W in their roots than wild-type plants. In their shoots they accumulated significantly more Cr and somewhat more V and W. Shoot Cd accumulation was significantly lower than in wild-type, and As levels were somewhat reduced. Compared to wild-type plants, sulfur accumulation was enhanced in roots of SHST1 plants but not in shoots. Together these results suggest that SHST1 can facilitate uptake of other oxyanions in addition to sulfate and that SHST1 mediates uptake in roots rather than root-to-shoot translocation. Since SHST1 overexpression led to enhanced accumulation of Cr, Cd, V, and W, this approach shows some potential for phytoremediation, especially if it could be combined with the expression of a gene that confers enhanced metal translocation or tolerance.     

Total Contents and Sequential Extraction of Heavy Metals in Soils Irrigated with Wastewater,Akaki, Ethiopia

The Akaki River, laden with untreated wastes from domestic, industrial, and commercial sources, serves as a source of water for irrigating vegetable farms. The purpose of this study is to identify the impact of waste-water irrigation on the level of heavy metals and to predict their potential mobility and bioavailability. Zn and V had the highest, whereas Hg the lowest, concentrations observed in the soils. The average contents of As, Co, Cr, Cu, Ni, Zn, V, and Hg of both soils; and Pb and Se from Fluvisol surpassed the mean + 2 SD of the corresponding levels reported for their uncontaminated counterparts. Apparently, irrigation with waste water for the last few decades has contributed to the observed higher concentrations of the above elements in the study soils (Vertisol and Fluvisol) when compared to uncontaminated Vertisol and Fluvisol. On the other hand, Vertisol accommodated comparatively higher average levels of Cr, Cu, Ni, Zn, etc V, and Cd, whereas high contents of Pb and Se were observed in Fluvisol. Alternatively, comparable levels of Co and Hg were found in either soil. Except for Ni, Cr, and Cd in contaminated Vertisol, heavy metals in the soils were not significantly affected by the depth (0–20 and 30–50 cm). When the same element from the two soils was compared, the levels of Cr, Cu, Ni, Pb, Se, Zn, V, Cd at 0–20 cm; and Cr, Ni, Cu, Cd, and Zn at 30–50 cm were significantly different. Organic carbon (in both soils), CEC (Fluvisol), and clay (Vertisol) exhibited significant positive correspondences with the total heavy metal levels. Conversely, Se and Hg contents revealed perceptible associations with carbonate and pH. The exchangeable fraction was dominated by Hg and Cd, whereas the carbonate fraction was abounded with Cd, Pb, and Co. conversely, V and Pb displayed strong affinity to reducible fraction, where as Cr, Cu, Zn, and Ni dominated the oxidizable fraction. Cr, Hg, Se, and Zn (in both soils) showed preference to the residual fraction. Generally, a considerable proportion of the total levels of many of the heavy metals resided in non residual fractions. The enhanced lability is generally expected to follow the order: Cd > Co > Pb > Cu > Ni > Se > V and Pb > Cd > Co > Cu > Ni > Zn in Vertisol and Fluvisol, respectively. For the similar wastewater application, the soil variables influence the status and the distribution of the associated heavy metals among the different soil fractions in the study soils. Among heavy metals that presented relatively elevated levels and with potential mobility, Co, Cu, Ni (either soil), V (Vertisol), Pb, and Zn (Fluvisol) could pose health threat through their introduction into the food chain in the wastewater irrigated soils.     

Phytoremediation of heavy metals by <Emphasis Type="Italic">Eichhornia crassipes</Emphasis>

Eichhornia crassipes was tested for its ability to bioconcentrate 8 toxic metals (Ag, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) commonly found in wastewater from industries. Young plants of equal size were grown hydroponically and amended with 0, 0.1, 0.3, 0.5, 1.0, 3.0, and 5.0 mM of each heavy metal individually for 21 days. The test plant had the lowest and the highest tolerance indices for Hg and Zn, respectively. A significant (P ≤ .05) reduction in biomass production was observed in metal treated plants compared with the control. All strace elements accumulated to higher concentrations in roots than in shoots. Trace element concentrations in tissues and the bioconcentration factors (BCF) were proportional to the initial concentration of individual metal in the growth medium and the duration of exposure. From a phytoremediation perspective, E. crassipes is a promising plant species for remediation of natural water bodies and/or wastewater polluted with low levels of Zn, Cr, Cu, Cd, Pb, Ag and Ni.     

TOXIC METALS IN SURFACE WATERS FROM COAL ASH1

ABSTRACT: The concentration of 10 [titanium (Ti), manganese (Mn), copper (Cu), chromium (CR), zinc (Zn), arsenic (As), selenium (Se), cobalt (Co), cadmium (Cd), and mercury (Hg)] toxic elements were measured in the water, benthic sediment, plants, invertebrates, and vertebrates of an ash basin and its drainage system at a coal-fired power plant of the Savannah River Project, Aiken, S.C., over a period of two years. During 12 months of this period the basin was essentially filled and little settling of ash occurred. In the remaining 12 months, dredging had been completed, adequate settling occurred and most of the effluent turbidity was removed. All elements were more concentrated in sediment and biota than in water, and five (Mn, Cu, As, Zn, and Se) were biomagnified by at least one biotic component as compared to concentration in benthic sediment. Plants had high accumulations of Ti, Mn, As, and Hg; invertebrates had high accumulations of Co, Hg, Cu, Cr, Cd, and As; and vertebrates greatly biomagnified Se and Zn. The streamlined biotic community of the system accomplished major removal of Mn, Zn, As, Se, and Cd from the effluent. The magnitude of bioaccumulation of Ti, Mn, Zn, As, Se, Cd, and Hg was increased during the period of adequate settling in the basin.     

柴窝堡湖表层底泥重金属污染评价

研究了乌鲁木齐市柴窝堡湖表层底泥的重金属含量,并采用Hakanson潜在生态危害指数法对底泥中的重金属潜在生态风险进行评价。结果表明:底泥中Cu、Zn、Pb、Cd含量均超出乌鲁木齐市土壤背景值。除湖心区外,Cd在5个监测区域中的潜在生态危害均为中等;其它重金属在5个采样点的潜在生态危害均为轻微。各重金属间的相关性分析表明,Zn与Cu,Pb与Cd、Cu呈显著正相关,说明这4种元素污染源可能相同。柴窝堡湖表层底泥受到Cu、Zn、Pb、Cd污染,需采取相应措施防止重金属由底泥进入水相。     

The characterization of total and leachable metals in foundry molding sands

Waste molding sands from the foundry industry have been successfully used as a component in manufactured soils, but concern over metal contamination must be addressed before many states will consider this beneficial use. Since there is little data available on this topic, the purpose of this study was to characterize total and leachable metals from waste molding sands. A total elemental analysis for Ag, Al, As, B, Ba, Be, Cd, Co, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Pb, Sb, V, and Zn was conducted on 36 clay-bonded and seven chemically bonded molding sands. Total metal concentrations in the molding sands were similar to those found in agricultural soils. The leaching of metals (i.e. Ag, As, Ba, Be, Cd, Cr, Cu, Ni, Pb, Sb, and Zn) was assessed via the toxicity characteristic leaching procedure (TCLP), synthetic precipitation leaching procedure (SPLP), and ASTM water leach test. Based on the TCLP data, none of the 43 molding sands would meet the Resource Conservation and Recovery Act (RCRA) characteristic for toxicity due to high Ag, As, Ba, Cd, Cr, and Pb. Compared to the TCLP results, the metal concentrations were generally lower in the SPLP and ASTM extracts, which is likely related to the buffering capacity of the extraction fluids.     

杭州城区河道底泥重金属污染及潜在生态风险评价

对杭州城区34条河道45个点位河道底泥进行采样,分析了pH及汞、砷、铅、铬、镉、铜、锌、镍等重金属含量,并进行污染及潜在生态风险评价。结果表明,监测点位的底泥为中性偏碱性,重金属含量分布不均,且范围波动很大,部分河道底泥重金属中汞、铅、镉、铬、锌、镍等有不同程度的超标,少数河道镉、铬、锌污染严重;按《农用污泥中污染物控...     

因子分析法在污染源解析方面的应用

针对长春市存在污染的46个土壤采样点,以Hg、Cd、Pb、As、Cu、Cr、Zn七种重金属元素指标作因子分析,从而为长春市表层土壤重金属污染成因的解释提供一定的理论依据。     

Source-separated municipal solid waste compost application to Swiss chard and basil

A growth room experiment was conducted to evaluate the bioavailability of Cu, Mn, Zn, Ca, Fe, K, Mg, P, S, As, B, Cd, Co, Cr, Hg, Mo, Na, Ni, Pb, and Se from a sandy loam soil amended with source-separated municipal solid waste (SSMSW) compost. Basil (Ocimum basilicum L.) and Swiss chard (Beta vulgaris L.) were amended with 0, 20, 40, and 60% SSMSW compost to soil (by volume) mixture. Soils and compost were sequentially extracted to fractionate Cu, Pb, and Zn into exchangeable (EXCH), iron- and manganese-oxide-bound (FeMnOX), organic-matter (OM), and structurally bound (SB) forms. Overall, in both species, the proportion of Cu, Pb, and Zn levels in different fractions followed the sequence: SB > OM > FeMnOX > EXCH for Cu; FeMnOX = SB > OM > EXCH for Pb; and FeMnOX > SB = EXCH > OM for Zn. Application of SSMSW compost increased soil pH and electrical conductivity (EC), and increased the concentration of Cu, Pb, and Zn in all fractions, but not EXCH Pb. Basil yields were greatest in the 20% treatment, but Swiss chard yields were greater in all compost-amended soils relative to the unamended soil. Basil plants in 20 or 40% compost treatments reached flowering earlier than plants from other treatments. Additions of SSMSW compost to soil altered basil essential oil, but basil oil was free of metals. The results from this study suggest that mature SSMSW compost with concentrations of Cu, Pb, Mo, and Zn of 311, 223, 17, and 767 mg/kg, respectively, could be used as a soil conditioner without phytotoxic effects on agricultural crops and without increasing the normal range of Cu, Pb, and Zn in crop tissue. However, the long-term effect of the accumulation of heavy metals in soils needs to be carefully considered.     

四川东部沱江茎瘤芥产地重金属特征及其富集规律研究

通过对四川省沱江乡榨菜种植区土壤和榨菜中重金属的分布特征进行调查分析。结果表明，菜头叶茎中（Zd、Cr、（Zu、Hg、As、Pb6种重金属元素的含量一般随着土壤中此6种重金属元素含量的增加而增多，但分析样品中也有部分样点表现出异样趋势，通过分析此异常主要是人为活动影响造成的。菜头叶茎中对此6种重金属元素均表现出较高富集性，其中尤以cd最为严重，富集系数高达12．14。     

河南农田土壤重金属污染状况及其评价

在河南境内取自农田土壤102例表层样品，分析了其中的Cr、Zn、Cu、Pb、Ni、As等8种重金属元素的含量。结果表明：河南农田土壤中除Cr偶有超出我国《土壤环境质量标准》（GB15618—1995）二级标准的土样外，其他项目均不超标，重金属污染由高到低排序为Cr〉Zn〉Ni〉Cd〉Hg〉Cu〉Pb〉As。重金属元素在河南各土壤利用类型中分布规律不明显，按4种主要土壤利用类型考查来看，重金属污染程度大小排序为：果园地〉水田〉菜地〉其他粮田；河南农田土壤综合污染指数总平均为0．981，土壤总体为尚清洁，重金属污染处于警戒水平；河南农田土壤中Cr含量较高的土壤主要是粗骨土与石质土，其天然本底值较高。     

四川东部沱江乡茎瘤芥产地的地球化学特征

通过对四川省东部沱江乡茎瘤芥产区土壤的地球化学特征研究和茎瘤芥产区的土壤测试分析，并将其与全国土壤背景值比较，摸清了茎瘤芥产区土壤的元素本底特征。沱江乡茎瘤芥产区土壤Zn、Fe、Mn、Mg、K、B、P元素含量高于全国土壤平均含量，有益元素Mo、Ca、Si、Se均比全国平均值低，重金属Cr、Hg、Cd、Pb含量比全国平均值高，As元素含量则低于全国平均值水平，产区土壤中存在的Cd元素超出国家环境质量一级标准，但符合二级土壤质量标准，其他元素符合绿色蔬菜产地环境标准。     

Long-term biosolids application effects on metal concentrations in soil and bermudagrass forage

The long-term application of biosolids that periodically contained elevated metal concentrations has raised questions about potential effects on animal health. To address these concerns, we determined metal concentrations (As, Cd, Cu, Pb, Hg, Mo, Ni, Se, and Zn) in both soil and bermudagrass [Cynodon dactylon (L.) Pers.] forage from 10 fields in the following categories of biosolids application: six or more years (>6YR), less than six years (<6YR), and no applications (NS). Soil metal concentrations in all groups were similar to values reported for mineral soils in Georgia, and well below USEPA cumulative limits. Average metal concentrations in the forage were below the maximum tolerable level (MTL) for beef cattle, although two biosolids-amended fields in the >6YR group produced forage that was at or near the MTL for Cd and Mo, and one field in the <6YR group produced forage above the MTL for Cd. The Cu to Mo ratios in forage decreased with increasing time of sludge application, with the average in the >6YR group at a proposed 5:1 Cu to Mo ratio limit to protect ruminant health. Sulfur concentrations in the forage from all three groups was near the MTL of 4 g kg(-1). The study indicated that toxic levels of metals have not accumulated in the soils due to long-term biosolids application. Overall forage quality from the biosolids-amended fields was similar to that of commercially fertilized fields; however, due to the relatively high S and potential for a low Cu to Mo ratio, Cu supplements should be used to ensure ruminant health.     

密云水库上游土壤重金属污染调查评价

文章对密云水库周边及上游地区（北京境内）的污染状况作了初步评价。研究结果发现密云水库周边及上游地区重金属污染以Cr和Hg为主，丰亡牛河上游为污染最严重地区，清水河上游、潮河下游放马峪地区、德田沟-崎峰茶地区受Cr元素轻度污染。这些地区土壤重金属污染的主要原因是由于金属矿山不合理堆放的尾砂及废矿石等人为因素所致。     

九寨沟白水河污染特征研究

通过对2012年4月～2013年3月九寨沟白水河不同断面水样分析,研究了《地表水环境质量标准》（GB3838—2002）中表1“地表水环境质量标准基本项目”的含量变化,并对铬、镉、硒、铜、汞、锌、铅、砷、氨氮、高锰酸盐指数进行污染状况评价。结果显示：镉、铜、汞、锌、铅均未检出;对铬、砷、硒、氨氮、高锰酸盐指数等有检出项目进行单项污染指数和内梅罗综合污染指数评价,水样中铬、砷、硒、氨氮、高锰酸盐指数全年监测平均浓度分别为0．294μg／L、0．024μg／L、0．084μg／L、0．187mg／L、0．695mg／L,用国家水质环境标准的一级标准,所有监测点位（PN〈1）未超标。从单因子污染指数来看,高锰酸盐指数在4月、7月、10月P,〉1,属于轻度污染,初步推断人为活动所致。通过本文的研究发现九寨沟水质依然较好,未受到污染。     

Fate of biosolids trace metals in a dryland wheat agroecosystem

Biosolids land application for beneficial reuse applies varying amounts of trace metals to soils. Measuring plant-available or total soil metals is typically performed to ensure environmental protection, but these techniques do not quantify which soil phases play important roles in terms of metal release or attenuation. This study assessed the distribution of Cd, Cr, Cu, Mo, Ni, Pb, and Zn associated with soluble/exchangeable, specifically adsorbed/carbonate-bound, amorphous Mn hydroxyoxide-bound, amorphous Fe hydroxyoxide-bound, organically complexed, and residual inorganic phases. Biosolids were applied every 2 yr from 1982 to 2002 (except in 1998) at rates of 0, 6.7, 13.4, 26.8, and 40.3 dry Mg biosolids ha(-)(1) to 3.6- by 17.1-m plots. In 2003, 0- to 20-cm and 20- to 60-cm soil depths were collected and subjected to 4 mol L(-1) HNO(3) digestion and sequential extraction. Trace metals were concentrated in the 0- to 20-cm depth, with no significant observable downward movement using 4 mol L(-1) HNO(3) or sequential extraction. The sequential extraction showed nearly all measurable Cd present in relatively mobile forms and Cr, Cu, Mo, Ni, Pb, and Zn present in more resistant phases. Biosolids application did not affect Cd or Cr fractionation but did increase relatively immobile Cu, Mo, and Zn phases and relatively mobile Cu, Ni, and Pb pools. The mobile phases have not contributed to significant downward metal movement. Long-term, repeated biosolids applications at rates considered several times greater than agronomic levels should not significantly contribute to downward metal transport and ground water contamination for soils under similar climatic conditions, agronomic practices, and histories.     

Plant growth and uptake of mineral elements at an oily sludge landfarming site in Kuwait

Oily sludge landfarmed in Kuwait soil contains higher concentrations of certain elements than that of the untreated of, soil, e.g. S, Cu, Cr, Zn, Pb, Ni, Mo and V. The growth and elemental content of three different plants grown on a sandy soil previously treated with different concentrations of oily sludge were studied. Tested plants differed in their response to landfarmed oily sludge; ryegrass was the least affected followed by oats, then barley. Uptake of elements differed both qualitatively and quantitatively between test plants. In barley, Zn increased in plants cultivated in soil treated with oily sludge, whereas other metal concentrations were reduced or not affected, namely, Cu, Pb, Ni, V. The uptake of P was greater in plants grown on treated soil compared with those on untreated soil, whereas Na, Ca, K, were either reduced or unaffected. In oats, Zn, Ni, Cu, Pb, V, were not significantly changed. Uptakes of K, Ca, P, and Na in plants from treated soil were higher than that of the control. In ryegrass, heavy metal concentrations were either reduced or remained the same as that of the control. In all cases, concentrations of essential heavy metals and other true elements under investigation were still lower than the levels considered to be sufficient for micronutrients. Thus, the oily sludge was a source of certain micro-nutrients which were deficient in the sandy soil. Further, it appears that uptake and distribution of elements in plant tissues were both highly variable according to the plant, species, and the soil characteristics.     

重庆市城区饮用水源健康风险评价

通过对重庆市8个饮用水源地枯水期水体中NH3-N、CN、As、Hg、Cr^＋6、Pb、Cd、Cu、F和挥发酚的浓度进行了调查研究，应用美国环保局推荐的健康风险评价模型对重庆市饮用水源水中污染物引起的健康风险作了评价。结果表明，污染物平均浓度范围分别为NH3-N：0．119—0.740mg／L，CN：0．002—0．004mg／L，As：0．001—0．007mg／L，Hg：0．000001—0．00005mg／L，Cr^＋6：0．004—0.023mg／L．Pb：0．004—0．053mg／L．Cd：0．00035—0．005mg／L．Cu：0．0005—0．0254mg/L，F：0．140—0．335mg／L，挥发酚：0．001—0．0027mg／L。重庆市通过饮水途径引起的非致癌健康风险中Pb的风险最大，F次之，两者风险水平在10^-8～10^-9／a；Cr^＋6引起的致癌风险最大达到10^-4／a；以长江为饮用水源的人群总健康风险大于嘉陵江，其健康风险达到EPA要求，但高于国际辐射防护委员会（ICRP）的最大可接受风险水平。     

河流底泥重金属污染及潜在生态风险评价——以湘江株洲段为例

通过对湘江株洲段6个监测断面左右两岸共32个底泥样品重金属Pb,Zn,Cd,As,Hg和Cr质量比进行分析研究,并进行潜在生态风险评价。结果表明：霞湾断面是重金属富集最严重的断面;Cd,Hg和As的含量均超过GB15618—1995三级标准和长沙-湘潭-株洲3市土壤背景值;重金属含量大部分分布特征为右岸高于左岸;从重金属污染的潜在生态风险看,湘江株洲段各监测断面潜在生态风险都很高;各重金属元素对生态风险影响程度从大到小的顺序为：Hg〉Cd〉As〉Pb〉Zn〉Cr。