绿洲土Cd、Pb、Zn、Ni复合污染下重金属的形态特征和生物有效性

通过模拟基于干旱区绿洲土壤Cd-Pb-Zn-Ni复合污染下的油菜盆栽试验,采用Tessier五步连续浸提法探究了重金属复合污染对油菜生长的影响及其各形态的转化归趋和生物有效性.结果显示,随着Cd-Pb-Zn-Ni复合胁迫水平的升高,油菜的干重先增加后减小,根系的生长由促进作用转变为抑制作用;对照土壤中4种重金属元素均以残渣态为主要赋存形态,可交换态的含量均很小;随着外源重金属的添加,油菜种植土壤中4种重金属元素的各形态含量随之增加,Cd、Pb、Zn的可交换态和Ni的碳酸盐结合态对外界胁迫响应强度最大,Cd、Pb、Zn、Ni的活性增加,且Cd、Pb的主要赋存形态迅速转变为碳酸盐结合态和铁锰氧化态,Zn的主要赋存形态由残渣态和碳酸盐结合态过渡到碳酸盐结合态和铁锰氧化态,Ni的主要赋存形态为碳酸盐结合态;Cd、Zn在茎叶中的含量大于根系,Pb、Ni反之,油菜能将Cd、Zn更多的运输至茎叶,Pb、Ni则主要积累在根系;油菜茎叶吸收Cd和油菜各部位吸收Zn的主要贡献形态为可交换态,根吸收Cd的主要贡献形态由可交换态转变为有机结合态,根吸收Pb和油菜各部位吸收Ni的主要贡献形态为碳酸盐结合态.     

稻麦轮作下水稻土重金属形态特征及其生物有效性

在成都平原稻麦轮作下86个土样中重金属全量和各形态含量分析的基础上,采集分析相应点位上种植的主要粮食作物小麦和水稻籽粒的重金属含量,通过描述性统计分析、相关性分析及线性回归方程的模拟,研究了土壤中重金属的形态分布特征及其生物有效性。统计分析结果表明：土壤中Cr、Cu、Pb、Zn各形态含量的分配顺序为：残渣态〉有机物结合态〉铁锰氧化物结合态〉碳酸盐结合态〉可交换态,而Cd各形态含量的分配顺序为：铁锰氧化物结合态〉残渣态〉碳酸盐结合态〉有机物结合态〉可交换态。若以活性态（非残渣态含量）而论,Cd的活性最高,Cr的活性最低。除Cr外,各元素全量与各活性形态之间的关系较为密切。土壤中全Cd含量与4种活性形态Cd含量间的相关性均达极显著水平;Cu、Zn全量分别与其铁锰氧化物和有机物结合态含量,Pb全量分别与其可交换态和铁锰氧化物含量间的相关系数达显著或极显著水平。用卫生部颁布的食品中重金属限量卫生标准评价稻麦籽粒重金属累积情况,其结果表明,小麦籽粒（旱作）中的Cd、Cr、Cu、Pb分别超标14.71%、8.70%、6.50%和17.40%,而水稻籽粒（水作）仅有Pb和Cd含量超标10.90%和8.70%。不同形态重金属对水稻和小麦籽粒中重金属累积的影响效应不同，从多元线性回归方程的回归系数来看：稻一麦籽粒中Cd含量受到土壤中各活性形态Cd含量的影响。除铁锰氧化态Cd和有机物结合态Cd含量分别对小麦和水稻籽粒中Cd的累积表现出负效应外，其余均为正效应。可交换态Cu含量对稻-麦籽粒Cu累积的效应最大，其次受碳酸盐结合态Cu含量的影响。稻一麦籽粒Pb含量的累积受土壤各活性态Pb含量影响效应的差异不甚明显。稻-麦籽粒Zn含量与土壤各活性态Zn含量间无显著线性关系。     

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．     

施用污泥对土壤重金属形态分布和生物有效性的影响

采用盆栽技术和BCR连续浸提法研究了污泥的添加对土壤Cd、Pb、Cu和Zn形态分布的影响及重金属在黑麦草-施污泥土壤中迁移转化规律.结果表明:污泥的添加使土壤中生物有效态的Cd和Zn含量显著增加,生物有效态Pb含量显著降低,残渣态Pb的比例较CK增加了33.3％～74.5％,而可交换态和可还原态Cu含量在污泥与土壤添加比为1∶1时,仅占总量的0.7％和0.2％.污泥的添加能促进黑麦草对Cd、Cu和Zn的吸收,抑制对Pb的吸收.多元线性回归分析结果表明,黑麦草体内Cd、Zn和Cu含量分别与土壤中可还原态Cd、Zn和可氧化态Cu含量存在正相关,草体中Pb的含量则受土壤中可交换态和可氧化态Pb含量共同影响.种植黑麦草后根际土中可氧化态Cd和Cu分别向可交换态Cd和残渣态Cu转化,可交换态和可还原态Zn向可氧化态Zn转化,Pb的生物有效性基本未受影响.     

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.     

强还原过程对设施菜地土壤重金属形态转化的影响

设施菜地由于污水灌溉、粪肥施用等导致重金属污染.本文通过土柱淹水同时添加玉米秸秆培养和后期通水淋洗,研究强还原法对设施土壤重金属(Cd、Cu、Pb和Zn)形态转化的影响.结果表明: 强还原处理使土壤pH显著降低,玉米秸秆处理变化更显著;土壤氧化还原电位(Eh)迅速下降至-280 mV左右.玉米秸秆处理可以促进土壤中Cd、Cu、Pb和Zn活化,第9天土壤中有机物及硫化物结合态和残渣态Cd、Cu、Pb和Zn含量比重下降;至15 d培养结束,土壤中4种重金属含量较对照分别减少18.1%、19.0%、16.1%和15.7%.玉米秸秆处理可以增加土壤中Cd和Zn的溶出量,但是Cu的溶出量减少;胶体结合态Cd和Pb含量较对照增加、Cu较对照显著减少、Zn没有显著变化.强还原可以引起设施土壤重金属活化,提高蔬菜积累重金属的风险,而且其随土壤水分的运移可能导致水体的污染.     

芜湖钢铁厂周边土壤及油菜籽中镉、铜、锌、铅含量和形态分布研究

研究了污染土壤、油菜籽中Cd、Cu、Zn、Pb含量、形态分布特征和重金属富集状况及可能存在的生物毒性.结果表明,土壤中Cd、Zn、Pb以铁锰氧化物结合态、Cu以残留态占5种形态最高比例,分别为31.1%、39.3%、53.79%、46.24%;Cd、Pb交换态比例较高,为23.47%、16.32%,Cu、Zn的交换态比例较小,为3.14%、0.54%;土壤中不同重金属与各重金属形态相关关系有差别,5种重金属形态转化为有效态重金属难易程度不同;油菜籽和油菜籽壳中不同重金属累积趋势有差异,Cu易在油菜籽壳中累积,Cd、Zn、Pb易在油菜籽中累积;油菜籽中不同重金属累积率不同,Cd累积率最高,为0.56.油菜籽中重金属累积率与土壤中重金属总量呈显著负相关关系(P＜0.05),土壤中重金属的形态、转化差异是此种负相关关系的主要原因;油菜籽中Cd、Cu、Pb以氯化钠态为主,分别为32.50%、22.94%、34.69%,Zn以EDTA态为主,为45.97%.油菜籽中重金属形态可能影响其毒性,但其毒性的人类膳食风险还需进一步研究证实.油菜籽中重金属形态与油菜中重金属总量相关性不好.     

利用乙二胺四乙酸淋洗修复重金属污染的土壤及其动力学

通过室内模拟试验,采用振荡淋洗的方法研究了乙二胺四乙酸(EDTA)浓度、pH、淋洗时间对重金属去除效果的影响.利用一级反应动力学模型对试验数据进行拟合,并测定了EDTA处理前后土壤中重金属形态的变化.结果表明,EDTA溶液在浓度为0.1 mol·L^-1、pH 7、淋洗时间1 d的条件下能达到对污染土壤重金属的最大去除率,去除率分别为Cd 89.14%、Pb 34.78%、Cu 14.96%、Zn 45.14%.模型拟合结果表明,Cd的质量转移系数最大,其次是Zn、Pb和Cu.说明在土壤淋洗过程中,Cd和Zn最先达到质量转移的平衡状态,然后是Pb和Cu.形态分级结果表明,EDTA能有效地去除交换态、碳酸盐结合态和氧化物结合态重金属,而对有机态和残余态部分重金属作用效果不明显.     

铜尾矿库区土壤与植物中重金属形态分析

对铜陵铜尾矿区土壤和植物中重金属形态进行了研究.结果表明,尾矿库区种植地极端贫瘠,有机质含量仅2.6～.8 g·kg^-1,而土壤Cu、Cd、Pb、Zn含量皆高于对照土壤,其中Cu含量达809.30～1 39.4 mg·kg^-1,Cd含量达3.2～6.3 mg·kg^-1,达到对照土壤30～60倍.结缕草和三叶草体内重金属含量与土壤重金属交换态及有机结合态含量成正相关,与碳酸盐结合态、铁锰氧化物结合态成显著或极显著负相关,与矿物态含量相关性不显著.在两种优势植物中,Cu、Zn、Pb均以活性较低的醋酸提取态、盐酸提取态和残渣态为主;Zn在根系和茎叶中,NaCl提取态占有较大比例,而Cd均以NaCl提取态为主.     

施污土壤重金属有效态分布及生物有效性

以城市污泥为研究对象,将城市污泥与土壤按照一定的质量比配成污泥混合土壤.采用6种不同性质提取剂(0.05mol/L EDTA、0.1 mol/L CH3 COOH、0.01 mol/L CaC12、1 mol/L CH3COONH4,0.05 mol/L NaHCO3和0.05 mol/L Tris-HCl)分别对污泥混合土壤中重金属(Cd、Pb、Cu和Zn)的螯合态、酸溶态、中性交换态、中性结合态、碱性交换态和蛋白质结合态进行提取,考察污泥的添加对土壤中不同形态重金属的消长规律.通过黑麦草盆栽试验,探究污泥混合土壤中不同形态重金属的植物可利用性.结果表明:污泥混合土壤中重金属螯合态比例较大,占总量的20.3％-40.0％;其次为酸溶态和中性结合态,而中性交换态、碱性交换态和蛋白质结合态的含量较低.污泥的添加促进了黑麦草对Cd、Cu和Zn的吸收,在污泥添加率为44.4％时根部对其吸收量达最大,分别较CK处理增加了0.3、2.3和6.5倍.抑制了对Pb的吸收,在污泥添加率为37.5％时,根部对Pb的吸收较CK处理下降0.4倍.Pearson相关系数分析结果表明:污泥混合土壤中以螯合态、酸溶态和中性结合态存在重金属可被黑麦草吸收利用.     

Effect of carbide sludge (lime) on bioavailability and leachability of heavy metals during rotary drum composting of water hyacinth

Abstract

The bioavailability and leachability of heavy metals play a major role in the toxicity of heavy metals in the compost applied for soil conditioning. A rotary drum composter was used for the study of heavy metal bioavailability and leachability during water hyacinth composting with a mixture of cattle manure, sawdust and lime. Lime was added in 1, 2 and 3% to the mixture of water hyacinth, cattle manure and sawdust at a ratio of 6:3:1 respectively. Influences of physico-chemical parameters on heavy metal bioavailability and leachability were studied during the process. The bioavailability of heavy metals solubility and diethylene triamine penta-acetic acid extractability was examined. The toxicity characteristics leaching procedure (TCLP) test was performed for assessing the hazardous properties of compost. The nutrients and the total concentration of heavy metals were increased during the composting process. The lime was very effective in reducing water solubility, plant availability and leachability of the selected heavy metals (Zn, Cu, Mn, Fe, Ni, Pb, Cd and Cr) during the process. The addition of lime provided a buffer against the decrease in pH and a sufficient amount of Ca that would improve the metabolic activity during composting. The addition of an excess amount of lime slowed the metabolic activity of the microbes due to its high alkalinity. The TCLP test confirms that the heavy metals concentrations in the control and in the lime-amended compost were below the threshold limits.     

Heavy metal fractionation during the co-composting of biosolids,deinking paper fibre and green waste

Due to the introduction of the European Union Landfill Directive, composting has become a potentially viable disposal route for some organic wastes. As waste-derived compost is frequently added to soil to improve soil quality, it is important to quantify the environmental risk posed by potentially toxic elements contained within it. Here we used a sequential chemical extraction procedure to investigate the temporal dynamics of heavy metals (Cu, Zn, Pb and Ni) during the co-composting of biosolids, deinking paper fibre and green waste. Overall, composting over 26 weeks reduced the availability of Ni, had no effect on Pb and slightly increased the availability of Cu and Zn. We conclude that although the total Cu and Ni concentrations in the compost exceed legislative guidelines for land application, due to their recalcitrant nature within the compost, this compost posed very little threat to soil or plant quality if used in agriculture or land restoration.     

有机物料对污染土壤上水稻生长和重金属吸收的影响

采用盆栽试验,研究了施用有机碳源、菜籽饼和猪粪对污染土壤上水稻生长和重金属吸收特性的影响.结果表明： 施用菜籽饼和猪粪均能缓解重金属对水稻的毒害作用,促进水稻生长,显著增加地上部生物量和籽粒产量,降低糙米中重金属浓度;而有机碳源抑制水稻生长.与施用化肥相比,施用菜籽饼和猪粪处理的水稻籽粒产量分别增加128.3%和67.9%;施用菜籽饼处理的糙米Cd、Cu和Zn浓度分别降低47.6%、35.2%和21.5%,施用猪粪处理分别降低9.5%、21.2%和9.3%.土壤中DTPA提取态重金属浓度与水稻地上部生物量和重金属积累总量呈显著负相关.     

Heavy metal contamination of a mixed waste compost: Metal speciation and fate

The aims of this study were to assess changes in heavy metal availability in two contrasting feedstocks during aerobic composting, and the availability of said metals in the finished composts. A high C-to-N ratio mixed biodegradable municipal solid waste (MSW) feedstock was successfully composted on its own and in combination with green waste. Changes in heavy metal speciation throughout the composting process were studied using the modified BCR sequential extraction protocol. It was found that total Cu, Pb and Zn concentrations increased over time due to the progressive mineralization of the compost feedstock. Metals were fractionated differently within the two feedstocks, although only Cu showed significant redistribution (mostly to the oxidisable fraction) over the 5 month composting period. The MSW-derived composts performed comparably with other commercially-available composts in a series of plant growth trials. Plant metal accumulation was not influenced by the heavy metals present in the MSW-derived compost implying that they are not plant available. It is recommended that these relatively low value/quality composts may be used for remediation of acidic heavy metal contaminated sites.     

堆肥对土壤重金属垂直分布的影响与污染评价

对不同畜禽粪便堆肥与土壤重金属垂直分布的关系进行了研究．结果表明,在畜禽粪便堆肥过程中,粪堆下土壤pH值和有机质显著增加,其pH和有机质含量的垂直分布表现为从表层到底层逐渐降低．各种畜禽粪便粪堆下土壤Zn、Cd含量明显增高,且从表层到底层呈逐渐减小的趋势．鸡粪和猪粪堆下土壤Cu含量随土层深度增加而降低;牛粪堆下土壤Cu含量随土层深度增加没有明显的变化．自然条件下Cd和Zn在土壤系统中的迁移能力大于Cu．各粪堆下的部分土层Cu、Zn、Cd含量超过我国土壤环境质量一级标准．应用地质积累指数法对各土层污染评价的结果表明,只有肉鸡粪堆下0～10cm土壤和蛋鸡粪堆下0～40cm土壤受到轻度Zn污染,其它粪堆下各土层均未受到Cu、Zn、Pb和Cd污染．     

Can compost improve Quercus pubescens Willd establishment in a Mediterranean post-fire shrubland?

The aim of the study was to evaluate the effects of sewage sludge compost (control, 20 kg m(-2), 40 kg m(-2)) supplied to Quercus pubescens Willd seedlings planted in a post-fire calcareous site in Provence (France). Changes in soil properties, seedling survival, growth and nutrition were monitored 7 months, 1.5 years and 2.5 years after amendment, and possible trace metal contamination of soil and seedlings by compost was also evaluated. Compost improved overall soil fertility by increasing organic matter, cation exchange capacity, total N and exchangeable P, K, Mg and B concentrations, but 40 kg m(-2) induced a more significant and more durable effect than 20 kg m(-2). However, the compost had no effect on seedling survival and growth, but increased foliar P and B concentrations at 40 kg m(-2). No foliar contamination of seedlings by trace metals occurred, although amendment increased exchangeable Cu and Zn concentrations in soil. Compost P and exchangeable Cu and Zn concentrations could induce eutrophication and water pollution, and limit rates that can be applied without environmental hazard.     

Bioavailability and extraction of heavy metals from contaminated soil by Atriplex halimus

Pot experiments were performed to evaluate the phytoremediation capacity of plants of Atriplex halimus grown in contaminated mine soils and to investigate the effects of organic amendments on the metal bioavailability and uptake of these metals by plants. Soil samples collected from abandoned mine sites north of Madrid (Spain) were mixed with 0, 30 and 60 Mg ha⁻¹ of two organic amendments, with different pH and nutrients content: pine-bark compost and horse- and sheep-manure compost. The increasing soil organic matter content and pH by the application of manure amendment reduced metal bioavailability in soil stabilising them. The proportion of Cu in the most bioavailable fractions (sum of the water-soluble, exchangeable, acid-soluble and Fe–Mn oxides fractions) decreased with the addition of 60 Mg ha⁻¹ of manure from 62% to 52% in one of the soils studied and from 50% to 30% in the other. This amendment also reduced Zn proportion in water-soluble and exchangeable fractions from 17% to 13% in one of the soils. Manure decreased metal concentrations in shoots of A. halimus, from 97 to 35 mg kg⁻¹ of Cu, from 211 to 98 mg kg⁻¹ of Zn and from 1.4 to 0.6 mg kg⁻¹ of Cd. In these treatments there was a higher plant growth due to the lower metal toxicity and the improvement of nutrients content in soil. This higher growth resulted in a higher total metal accumulation in plant biomass and therefore in a greater amount of metals removed from soil, so manure could be useful for phytoextraction purposes. This amendment increased metal accumulation in shoots from 37 to 138 mg pot⁻¹ of Cu, from 299 to 445 mg pot⁻¹ of Zn and from 1.8 to 3.7 mg pot⁻¹ of Cd. Pine bark amendment did not significantly alter metal availability and its uptake by plants. Plants of A. halimus managed to reduce total Zn concentration in one of the soils from 146 to 130 mg kg⁻¹, but its phytoextraction capacity was insufficient to remediate contaminated soils in the short-to-medium term. However, A. halimus could be, in combination with manure amendment, appropriate for the phytostabilization of metals in mine soils.     

施用污泥对油菜根际养分和不同种类重金属的影响

根际是控制植物养分动态的重要因素,养分动态也影响着根际土壤环境。当土壤被污水污泥改良后,根际土壤中的养分和重金属性质也会发生变化。目前很少有人研究施用污泥的土壤中植物根系对根际重金属有效性和分布的影响。采用根垫—冰冻薄层切片法对施用污泥后土壤中油菜根际的养分和重金属分布情况进行研究,以期探明污泥改良土壤中根际重金属的活化特征。当土壤施用污泥后,根际土壤中DTPA提取态Zn,Cd,Ni,Mn,有效磷,有效钾和铵态氮被显著消耗,而根际土壤中DTPA提取态Cu没有明显的消耗或积累。当土壤中施用大量污泥时,根际土壤的pH值随着离根表面距离的增加而增加。无论土壤是否用污泥处理,油菜根际土壤中可交换态Cu都显著减少。当土壤被50%污泥改良时,在距离根表面0—2 mm处的油菜根际土壤中碳酸盐结合态,铁锰氧化物结合态,有机物结合态,残渣态的Cu和Zn都被消耗较多。污泥的施用对油菜的生长有促进作用。随着污泥施用量的增加,油菜地上部分Cu和Zn的含量没有显著变化。施用污泥量小于25%的土壤中,污泥没有增加重金属的可利用性和移动性。除了Cu,油菜根际土壤中DTPA提取态Zn,Cd,Ni的减少表明施用污泥的土壤中重金属的活化是非常有限的。     

Heavy metal bioavailability in a soil affected by mineral sulphides contamination following the mine spillage at Aznalcóllar (Spain)

A field experiment, lasting 14 months, was carried out in order to assess the effect of organic amendment and lime addition on the bioavailability of heavy metals in contaminated soils. The experiment took place in a soil affected by acid, highly toxic pyritic waste from the Aznalcóllar mine (Seville, Spain) in April 1998. The following treatments were applied (3 plots per treatment): cow manure, a mature compost, lime (to plots having pH < 4), and control without amendment. During the study two crops of Brassica juncea were grown, with two additions of each organic amendment. Throughout the study, the evolution of soil pH, total and available (DTPA-extractable) heavy metals content (Zn, Cu, Mn, Fe, Pb and Cd), electrical conductivity (EC), soluble sulphates and plant growth and heavy metal uptake were followed. The study indicates that: (1) soil acidification, due to the oxidation of metallic sulphides in the soil, increased heavy metal bioavailability; (2) liming succeeded in controlling the soil acidification; and (3) the organic materials generally promoted fixation of heavy metals in non-available soil fractions, with Cu bioavailability being particularly affected by the organic treatments.