根瘤菌对土壤铜、锌和镉形态分配的影响

以湖南郴州红壤和河北巩义褐土为供试土壤。制备Cu、Zn、Cd污染土壤。接种大豆根瘤菌(Rhi-zobium fredii)HN01,用连续提取法浸提土壤中不同形态的重金属．结果表明。褐土接种根瘤菌后固相结合态Zn总量降低10％。专性吸附态、氧化锰结合态和有机结合态Zn减少达9％～26％．红壤中结合态Zn的总量变化不显著,但专性吸附态和氧化锰结合态Zn含量显著减少。交换态Zn含量显著增加．褐土中接种根瘤菌抑制了Cu向土壤溶液的释放,固相结合态Cu总量增加18％,可交换态、专性吸附态、氧化锰结合态和有机结合态的Cu增加20％～54％．接种根瘤菌对土壤中Cd的溶解没有明显的抑制或促进作用,但改变了红壤中各形态Cd的含量高低顺序．Cd污染红壤中可交换态和有机结合态Cd含量分别增加22％和11％,专性吸附态和氧化锰结合态Cd分别减少14％和29％．根瘤菌对不同类型重金属及不同土壤中重金属形态影响的差异主要与土壤pH降低有关．     

外源水溶性有机物及温度对红壤铜形态的影响

利用模拟培养试验研究了外源水溶性有机物（DOM）添加量和培养温度对红壤中Cu形态的影响. 结果表明: 与不添加DOM比较, 添加不同量的DOM均可提高土壤中交换态Cu的含量、降低铁锰结合态Cu含量; 随着培养时间的延长,不同DOM添加量下土壤交换态Cu含量呈逐渐下降趋势;至试验结束时,DOM添加量为250 mg·L^-1时土壤交换态和碳酸盐结合态Cu含量最高, 添加量为500 mg·L^-1时铁锰结合态Cu含量最高;不同DOM添加量下, 土壤中有机结合态Cu含量较CK增加10.67%～23.66%. 在25 ℃和45 ℃温度条件下, 添加DOM后土壤交换态和铁锰结合态Cu含量均随培养时间的延长呈下降趋势, 但在5 ℃下变化趋势相反; 3种温度下添加DOM后土壤碳酸盐结合态Cu含量有随培养时间延长而增加的趋势. 随着培养温度的升高,土壤有机结合态Cu含量增加, 但在温度较低(5 ℃)时土壤残渣态Cu含量下降.     

Solid-phase distribution of heavy metals as affected by single reagent extraction in dredged sediment derived surface soils

ABSTRACT

EDTA is useful to assess mobile metal pools in polluted soils and sediments. There is a need to enhance our understanding of the significance of metal fractions released. The impact of single reagent extraction with 0.05 mol L^?1 EDTA on the solid phase distribution of trace metals in surface soils sampled from confined dredged sediment disposal sites was investigated. Not extracted and EDTA extracted soils were subjected to sequential extraction to fractionate the total contents into: (1) easily exchangeable and carbonate bound fraction; (2) reducible fraction; (3) oxidisable fraction; and (4) residual fraction. With EDTA, significant portions of metals associated with the acid extractable and reducible fractions were released. The oxidisable and residual fractions remained unaffected for most of the investigated metals except for the organic matter associated metals (Cu and Pb). A decrease in the residual fraction after EDTA-extraction for Cu and Pb was attributed to artifacts of the sequential extraction procedure.     

Status of copper in some calcareous and non-calcareous soils of Egypt

Summary To assess the status of copper in Egyptian soils, surface and subsurface soil samples were collected from various geographical regions of Egypt and of various genesis. The samples were analyzed for the total Cu, water-soluble plus exchangeable as well as the acid-extractable and EDTA-extractable Cu. The total Cu varied between 3.5 and 72.3 ppm. Less than 2% of this copper was in the soluble plus exchangeable form. The highest values of total and soluble plus exchangeable copper were found in the alluvial soils while the sandy soils had the least amounts. This was attributed to the high clay and organic matter content of the alluvial soils in addition to the dominance of montmorillonitic clay minerals in their fine fraction. The calcareous soils showed intermediate values of total and soluble plus exchangeable Cu due to their lower organic matter and clay mineral content. The clay mineralogy of these soils revealed the dominance of illitic and kaolinitic minerals which are relatively poor in Cu and other trace elements.Because of their relatively higher organic matter content, the alluvial soils had a large percentage (up to 43%) of their total Cu in the EDTA extractable form. The calcareous soils, on the other hand, had a large percentage (up to 52%) of their Cu in the acid-extractable form. The EDTA extractable Cu was correlated with the organic matter content of the soils. Since the pH of the EDTA extract was found to be dependent on the CaCO₃ content of the soils, it was suggested that the method be modified so that the final pH of the extract is constant for all soils.     

稻草和紫云英对土壤外源铜的形态及生态效应的影响

研究稻草和紫云英对红壤和潮土中外源铜的形态及其对水稻有效性的影响,结果表明稻草和紫云英均显著降低了交换铜的含量,提高了紧有机结合态和无定形氧化铁结合态铜的含量,交换态铜含量与土壤ｐＨ值及有机态铜含量呈显著负相关,稻草和紫云英显著地抑制了水稻根对铜的吸收,但在一定程度上促进了根铜向茎叶及茎叶铜向谷粒迁移,稻草显著降低了低糙米中铜的含量,紫云英降低潮土处理糙米中铜的含量但对红壤处理的糙米的铜含量则没有     

Phytotoxicity and distribution of copper in tropical soil amended with sewage sludge and copper sulfate

Abstract

A greenhouse experiment was conducted to evaluate phytotoxicity and distribution of Cu in a tropical soil amended with sewage sludge (Sw) and copper sulfate (CuSO₄.5H₂O). Samples of a clay soil from the State of Paraná, Brazil were collected at depth of 0–20; 20–40 and 40–60 cm, and brought to the laboratory to be properly accommodated in experimental units (PVC tubes). The Cu treatments were performed by the application of Sw (10 t ha-¹) amended with Cu (SB-T), and by CuSO₄. H₂O (WB-T). Lettuce plants were cultivated in the amended soil in order to predict the toxicity of the Cu. The experiment was conducted for 70 days, and then the lettuce plants and soil samples were collected for analysis. A sequential method was used to separate soil Cu into following fractions: exchangeable, amorphous iron oxide bound, crystalline iron oxide bound, organic matter bound and residual bound. The experimental results showed that Fe, Zn, K, P, Cu and organic matter amounts of the soil increased with the treatment SB-T. The toxic phyto-available Cu content in the soil for the lettuce plants was 80.00 mg kg^-1. A percolation study showed that the Cu contents were larger for the first 20 cm of depth, indicating that the metal was not transported down the soil profile. The Cu content of different fractions declined in an order residual > amorphous iron oxide > crystalline iron oxide > organic matter > exchangeable, regardless of treatment performed. Additionally, the Cu contents added from treatments were determined mainly in amorphous iron oxide fraction.     

Assessment of a heavy metals‐contaminated site using sequential extraction,TCLP, and risk assessment techniques

The mobility of selected heavy metals in contaminated soil at a previous industrial site in Brisbane, Australia, was assessed using a sequential extraction technique. Copper, Pb, Zn, Cr, Fe, and Mn were extracted from the soil solution/exchangeable, carbonate, Fe and Mn oxides, and organic matter fractions. The amounts of metals adsorbed by these fractions were used as an indicator of each metal's mobility in the soil. Copper and Pb were largely adsorbed by the organic and oxide fractions, while a significant amount of Zn was extracted from the carbonate fraction. The potential mobility and biological availability of the metals in these soils is Zn > Cr = Cu ≈ Pb. Soils were also analyzed using the toxicity characteristic leaching procedure (TCLP) to determine whether the contaminated soil could be disposed of by landfilling. The leachability of all metals from the soils was very low, with metal concentrations below the allowable limits. The TCLP also showed that Zn was the most mobile metal in these soils. An environmental and health risk assessment was undertaken, and it was concluded that the site did not represent a risk despite the “total”; concentrations of some metals being up to 40 times the investigation threshold value adopted in Australia.     

EDTA and industrial waste water improving the bioavailability of different Cu forms in contaminated soil

It is common to find that low bioavailability can prevent the phytoremediation process of heavy metal-contaminated soils. Heavy metals in soil are associated with various forms having different bioavailability. In this study, the bioavailability of various Cu forms in contaminated soils was investigated using ion-exchange resins, a sequential extraction procedure, and combined with methods including partial dissolution procedure, simulated Cu forms, seedling culture, pot experiment when treated with EDTA, or waste water from monosodium glutamate and citric acid production. Results showed that the bioavailability, in decreasing order of different Cu forms to tall fescue (Festuca arundinacea Schreb.) is: exchangeable Cu (EX-Cu) and organic matter bound Cu (OM-Cu)> Cu bound to carbonate (CAB-Cu)> Fe/Mn oxide bound Cu (OX-Cu)> residual Cu (RES-Cu). Effect of EDTA on the activation of Cu contaminated soil or simulated Cu and the uptake and translocation of tall fescue was better than that of monosodium glutamate waste water (MGW) and citric acid waste water (CAW). EDTA, CAW and MGW all improved the plant availability of different Cu forms in contaminated soil, which could be used in chelate-assisted phytoremediation of heavy metal polluted soil.     

贵州万山汞矿区污染土壤中汞的形态分布特征

利用优化Tessier连续化学浸提法对贵州万山汞矿区污染土壤中汞的形态分布进行研究.结果表明,稻田土壤中汞主要以残渣态形式存在(79.65%),其次为有机结合态(19.97%)、氧化态(0.31%)、特殊吸附态(0.04%)和溶解态与可交换态(0.03%);除特殊吸附态外,其他各形态汞含量均随距污染源距离增加而降低,特殊吸附态汞在分析土壤中含量变化不明显;生物可利用性(溶解态与可交换态和特殊吸附态)汞占总汞比例较低,但在污染土壤中其含量明显高于未受污染地区.     

Preliminary study on heavy metals contamination of soil using solid phase speciation and the influence on groundwater in Bozanta–Baia Mare Area,Romania

Abstract

A preliminary study on soil contamination with heavy metals and As based on solid phase speciation according to the Tessier scheme and the influence on groundwater in an area under anthropogenic influence (Bozanta-Baia Mare, Romania) was conducted. The partitioning of Al, As, Cd, Cu, Fe, Mn, Pb and Zn in five fractions is discussed in relation to soil characteristics, pH, organic matter content, mineralogical composition and distribution of the same elements in airborne particulate matter. The airborne particulate matter contains high quantities of As, Cd, Cu, Pb and Zn as exchangeable fraction. The sequential extraction carried out on soil samples revealed the main role of Fe-Mn oxides surface in the immobilization of metals. Organic matter has a specific role in complexation of Cu, Pb, As and Al, since high contents of these metals were recovered in the oxidizable fraction. Cadmium has a high selectivity for carbonate minerals. The amendment of soil with natural fertilizer increases the exchangeable fraction of metals with the highest toxicity. The available fraction for plants (exchangeable + carbonate-bound species) exceeded the alert values in soil, therefore the continuous monitoring of the area is necessary. The soil is unsuitable for agricultural use due to high contamination on surface with toxic elements resulted from anthropogenic activities. Groundwater is contaminated with very toxic elements (As, Cd and Pb) but also with Cu, Mn and Zn and is unsuitable as supply for drinking water.     

Removal of Heavy Metals from Contaminated Soil and Sediments Using the Biosurfactant Surfactin

The feasibility of using a biodegradable surfactant, surfactin from Bacillus subtilis, for the removal of heavy metals from a contaminated soil (890?mg/kg zinc, 420?mg/kg copper, 12.6% oil and grease) and sediments (110?mg/kg copper, 3300?mg/kg zinc) was evaluated. Results showed that after one and five batch washings of the soil, 25 and 70% of the copper, 6 and 25% of the zinc, and 5 and 15% of the cadmium could be removed by 0.1% surfactin with 1% NaOH, respectively. From the sediment, 15% of the copper and 6% of the zinc could be removed after a single washing with 0.25% surfactin/1% NaOH. The geochemical speciation of the heavy metals among the exchangeable, oxide, carbonate, organic, and residual fractions was determined by selective sequential extraction procedure. For both matrices, the exchangeable fractions were minimal, while the carbonate and the oxide fractions accounted for over 90% of the zinc present and the organic fraction constituted over 70% of the copper. Results after washing indicated that surfactin with NaOH could remove copper from the organic fraction, zinc from the oxide, and cadmium from the carbonate fractions. The residual fraction remained untouched. These experiments indicate that the sequential extraction studies could be useful in designing soil-washing procedures.     

Chemical fractionation of heavy metals in soils around oil installations,Assam

Abstract

The chemical fractionation of lead, cobalt, chromium, nickel, zinc, cadmium and copper in soils around Lakwa oil field, Assam, India was studied using a sequential extraction method. It is evident from the study that the residual fraction is the most important phase for the seven heavy metals under study. Among non-residual fractions metals are mostly associated with the Fe–Mn oxides fraction. The association of heavy metals with organic matter was observed in the following order: copper> cadmium> zinc> lead. The concentration of Pb in the carbonate fraction for both the seasons is higher compared with other metals, which may pose environmental problems due to its highly toxic nature. The comparatively low concentration of metals in the exchangeable fraction indicates low bioavailability. Correlations between physicochemical parameters and metal fractions of soil do not show consistent behaviour. The local mean values of metals when compared with the accepted values of normal abundance and geochemical background, indicates two to four fold increases in this area. However, the values are within the range of normal abundance. As well as from natural soil geochemical behaviour, anthropogenic influence might have a close bearing on the association of metals with the soil system in the studied area.     

Sludge-Derived Cu and Zn in a Humic-Gley Soil: Effect of Dissolved Metal-Organic Matter Complexes on Sorption and Partitioning

A sequential extraction scheme was combined with sorption isotherm analysis in order to investigate sorption of sewage sludge-derived Cu and Zn to the A-horizon of a humic-gley soil as a whole, and to the operationally defined exchangeable (1?M MgCl₂), carbonate (1?M NaOAc), Fe/Mn oxide (0.04?M NH₂OH.HCl), and organic (0.02?M HNO₃+30% H₂O₂) soil fractions. Sorption parameters were compared for a sample of sludge leachate (with 97.4% of Cu and 63.2% of Zn present as dissolved metal-organic matter complexes, as calculated by geochemical modeling involving MINTEQA2 and verified using an ion exchange resin method) with that of a reference solution exhibiting the same chemical characteristics as the leachate, except for the presence of dissolved organic material. Dissolved metal-organic matter complexes were found to significantly (P<0.05) depress sorption to the bulk soil and each fraction. The greatest depression of Cu and Zn sorption was observed for the exchangeable, carbonate, and Fe/Mn oxide fractions, while the organic fraction of the soil was the least affected. This reflects a greater affinity for the exchangeable, carbonate, and Fe/Mn oxide fractions by the free divalent metal (Cu²⁺, Zn²⁺), with sorption by these fractions attributed to cation exchange, chemisorption, and co-precipitation processes. The sorption characteristics of the organic fraction indicated that Cu and Zn sorption by soil organic matter mostly involved dissolved metal-organic matter complexes. This may be attributed to hydrophobic interactions between nonpolar regions of the dissolved metal-organic matter complexes and solid-phase soil organic matter.     

Phyto-availability and speciation change of heavy metals in soils amended with lignin as micro-fertilizer

Lignin is a primary byproduct from the black liquor treatment in paper making industries, its application as micro-fertilizer in agricultural land might provide a promising alternative to sewage discharge. However, application of such a micro-fertilizer might affect the soil properties and result in soil pollution. In this study, the effects of lignin application on phytoavailability and speciation change of heavy metals in soils were investigated. Greenhouse experiments showed that lignin application improved the growth of winter wheat (Triticum aestivum L.) in all three soils investigated. The increase of the biomass for wheat shoot was 59.7%, 39.8% and 12.3% for Beijing soil, Jiangxi soil and Dongbei soil, respectively. In contrast, lignin amendment decreased the concentrations of heavy metals in wheat shoots from 2.2% to 61.0%. Sequential extraction procedure of a three-step BCR was used to investigate the fraction distribution. The extractable fractions were specified as fraction B1: water soluble, exchangeable and carbonate bound or weakly specifically adsorbed; B2: Fe-Mn oxide bound; B3: organic matter and sulfide bound. The results showed that lignin application led to the redistribution of heavy metals in each fraction. Generally, heavy metals decreased in B1 and B2 fractions and increased in B3 fraction. Upon the results short-term application of lignin in agricultural land not only improves the growth of wheat but also reduces the phyto-abailability of heavy metal in wheat.     

The Adsorption Properties of Agricultural and Forest Soils Towards Heavy Metal Ions (Ni,Cu, Zn,and Cd)

Adsorption of Cu, Cd, Ni, and Zn in single and multi-metal solutions by agricultural and forest soils was investigated in batch sorption experiments. The results showed significant differences in sorption capacities of the studied soils. The selectivity order was as follows: agricultural soil? top forest soil > bottom forest soil. The adsorption sequence Cu > Zn > Ni > Cd was established for the agricultural and bottom forest soil, while the order for the top forest soil was Cu > Ni > Zn > Cd. The experimental isotherms for the metal sorption were described satisfactorily by the Freundlich and Langmuir models. The competitive adsorption experiment indicated a reduction in the amount of metals adsorbed by the soils from the multi-metal solution compared to the single metal solution. Properties of the soils, such as pH, content of clay and organic matter, exchangeable bases and hydrolytic acidity, showed a significant influence on adsorption capacities of the studied soils.     

模拟酸雨对污染土壤中Cd、Cu和Zn释放及其形态转化的影响

研究了模拟酸雨连续浸泡下污染红壤和黄红壤中重金属释放及形态转化．结果表明。随着模拟酸雨pH值下降,污染土壤中重金属释放强度明显增大;Cd、Zn释放量与酸雨pH值呈线性极显著负相关．Cu与酸雨pH值呈线性显著负相关．模拟酸雨作用下,污染红壤和黄红壤中Cd均以交换态为主;Cu则以有机结合态和氧化锰结合态为主;Zn在污染红壤中以残留态和交换态为主．在污染黄红壤中以残留态和有机结合态为主．土壤有机质含量和阳离子交换量对Cd、Cu、Zn的释放产生一定的影响并影响Cd、Zn的形态转化,但对Cu形态转化影响不明显,随着模拟酸雨酸度增大,污染红壤和黄红壤中重金属Cd、Cu的生物可利用态明显增多,但难解吸态Zn向生物有效态转化效应不明显．     

Quantitative speciation of heavy metals in soil and crops of agricultural fields of Islamabad,Pakistan

Abstract

Two root crops: carrot (Daucus carota) and spring onion (Allium fistulosum) and soil samples were selected from the agricultural fields located near Islamabad, Pakistan to determine their elemental content. Field soil speciation of the two crops was also carried out to analyse the correlation of the elements in field crop and soil. Concentrations of selected elements were evaluated in the leaf, stem, root and flowering part of the crops using flame atomic absorption spectrophotometry. The results showed that elements are mostly concentrated in soil rather than crop parts following the sequence Zn>Cu>Pb>Ni>Cr>Cd. Furthermore, soil speciation showed that Ni and Cr are more prevalent in the Fe–Mn oxide fraction, Zn and Cd as the carbonate bound fraction and Cu is found in the organic bound form. However, concentrations of Pb are similar across the carbonate, Fe–Mn oxide and organic bound fractions. The highest average concentration of Zn is found as the carbonate bound fraction (2.09 ± 0.005 mg kg^?1) and Cu as the organic bound (1.51 ± 0.029 mg kg^?1) in soil samples taken from the agricultural field of Daucus carota.     

干湿交替条件下三峡水库消落带土壤汞形态变化

对三峡水库消落带干湿交替条件下土壤汞赋存形态变化、影响因素和生物可利用性进行了模拟研究.结果表明: 干湿交替条件下土壤汞会发生形态转化和释放,总汞含量逐渐降低,两次“淹水-落干”后总汞含量降低了28.9%.土壤中不同汞形态所占比例分别为:水溶态汞(Hg-w)6.1%～16.8%;交换态汞(Hg-e)5.8%～12.9%;碳酸盐结合态汞(Hg-c)4.5%～17.7%;腐植酸结合态汞(Hg-h)12.5%～29.9%;有机质结合态汞(Hg-o)5.3%～12.8%,残渣态汞(Hg-r)34.5%～51.6%.土壤中汞形态以残渣态(Hg-r)为主,干湿交替条件下其所占比例有降低的趋势,腐植酸结合态汞(Hg-h)则逐渐增加,生物可利用态汞(Hg-w、Hg-e、Hg-c和Hg-h之和)总体呈增加趋势,易被水生生物利用并进入食物链,可能会增加水库生态系统的汞生态风险.     

Risk Element (As,Cd, Cu,Pb, and Zn) Contamination of Soils and Edible Vegetables in the Vicinity of Guixi Smelter,South China

Risk element (As, Cd, Cu, Pb, and Zn) contamination in soils and in two edible vegetables (Solanum melongena L. and Capsicum annum L.) was investigated in the vicinity of Guixi Smelter, South China. Soil As concentrations averaged 23.9 mg/kg. Sites near the smelter tailings recorded the highest levels of As and heavy metals in soils. The concentration order of heavy metals in soils was Cd < Pb < Zn < Cu. Cu and Cd in soils were abundant in the exchangeable and bound to carbonate fraction, while Pb and Zn were in the residual fraction, limiting their potential toxicity as pollutants. The proportions of the metals in the mobile fraction followed the order Pb < Zn < Cu < Cd. In Solanum melongena L. and Capsicum annum L., Zn concentration was the highest, followed by Cu, Cd, and Pb, different from that in soils and in the mobile fraction. Concentrations of heavy metals in the labile fractions in soils and in vegetables presented significant correlation (p < 0.05). Both of the two vegetables are not the Cu and Zn accumulators. As for Cd and As, Capsicum annum L. poses a higher risk to animal and human health than Solanum melongena L., with soil-plant transfer coefficients more than three. Root-stem is the main barrier for most of the heavy metals and As in the two vegetables, resulting in higher metal concentrations in roots relative to other plant tissues. The low stem-fruit transfer coefficients for Zn in Solanum melongena L. and for Pb in Capsicum annum L. suggested that very few of them could reach the fruits.     

The effect of physico-chemical parameters on speciation of trace metals insediments from inland and coastal waters of Ghana

The speciation of cadmium, lead, copper, zinc, manganese and iron into exchangeable, carbonate, reducible and organic bound fractions was studied in sediments from coastal and freshwater environments in Ghana. This was relevant as the species in which metals are stored within specific sediment components is important in determining their impact on the environment. For both coastal and inland sediments, a higher percentage of cadmium was associated with the more available exchangeable and carbonate fractions, while iron, zinc and manganese were mainly associated with the reducible and organic fractions. Lead and copper were found to have the greatest ability to form different species in the samples examined and were more evenly associated with all the fractions. The metals generally showed more ability to form different species in inland freshwaters than in coastal relatively saline waters. However, differences between inland and coastal waters were based more on whether the environments were oxidising or reducing than on whether they were fresh or saline. The metals may be divided into three groups of high mobility consisting of lead and copper; moderate mobility made up of cadmium, manganese and zinc; and low mobility, represented by iron.