柠檬酸、草酸和乙酸对污泥中镉、铅、铜和锌的去除效果

研究了柠檬酸、草酸和乙酸对污泥中Cd、Pb、Cu和Zn等重金属的去除效果,并分析了污泥中重金属的形态变化和生物有效性.结果表明,随着反应时间和酸浓度的增加,污泥中重金属（Cu除外）的去除率也相应增加.污泥加入柠檬酸溶液反应7h即可去除污泥中52.0%的Pb和74.2%的Zn,24h后可去除76.0%的Pb和92.5%的Zn,草酸和乙酸对重金属的去除率较低.柠檬酸去除的Pb和Zn主要以稳定态存在,并导致污泥中不稳定态重金属的比例上升,其中可交换态重金属浓度有不同程度的增加.虽然有机酸对Cd和Cu的去除率较低,但反应后可交换态Cd和Cu的浓度仍有小幅增加.     

柠檬酸、草酸和乙酸对污泥中镉、铅、铜和锌的去除效果

研究了柠檬酸、草酸和乙酸对污泥中Cd、Pb、Cu和Zn等重金属的去除效果,并分析了污泥中重金属的形态变化和生物有效性.结果表明,随着反应时间和酸浓度的增加,污泥中重金属（Cu除外）的去除率也相应增加.污泥加入柠檬酸溶液反应7 h即可去除污泥中52.0%的Pb和74.2％的Zn, 24 h后可去除76.0%的Pb和92.5%的Zn,草酸和乙酸对重金属的去除率较低.柠檬酸去除的Pb和Zn主要以稳定态存在,并导致污泥中不稳定态重金属的比例上升,其中可交换态重金属浓度有不同程度的增加.虽然有机酸对Cd和Cu的去除率较低,但反应后可交换态Cd和Cu的浓度仍有小幅增加.     

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2.6～5.8 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809.30～1 395.54 mg·kg^-1 ,Cd含量达3.25～6.35 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.     

淋洗法修复化工厂遗留地重金属污染土壤的可行性

通过室内模拟试验,采用振荡淋洗的方法研究了蒸馏水、HCl、H₃PO₄、草酸、CaCl₂等淋洗剂对化工厂遗留地污染土壤中重金属的淋洗效果,探讨了淋洗剂浓度、淋洗时间、淋洗次数等对淋洗效果的影响,并研究了HCl处理前后土壤中重金属形态的变化.结果表明：蒸馏水、H₃PO₄、CaCl₂等对Cr、Pb、Zn、Cu、Cd的去除率较低,大多数条件下重金属去除率均在1%以下,最大去除率仅为3.58%.2 mol·L^-1 HCl在土水比为1∶3、反应时间为1 h、2次淋洗的条件下可以达到最佳淋洗效果,Cr、Pb、Zn、Cu、Cd的去除率分别达到80.75％、88.69％、98.00％、79.33％和95.52％.形态分析结果表明,HCl能有效去除土壤中各种结合形态的重金属.     

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31.81%、39.83%、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.     

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.     

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。     

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．     

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.     

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.     

Chemical Extraction of Arsenic and Heavy Metals from Contaminated Soils Under High Temperature and Pressure Conditions in Abandoned Mines in South Korea

The chemical extraction of As and heavy metals from contaminated soils, sampled from the Geopoong and Keumpoong mines in South Korea, was investigated under subcritical conditions. Soil samples from the abandoned mines were heavily contaminated with As, Cd, Cu, Pb, and Zn. The extent of metal removed from the contaminated soils by extractants varied according to the chemical forms of the metals in the soils. When temperature increased, the extraction of As increased accordingly, showing 92-100% removal with 100 mM of NaOH at 300°C. In contrast, the extraction of cationic metals by citric acid and ethylenediaminetetraacetic acid (EDTA) decreased markedly at 200–300°C because their chelating ability was decreased via decarboxylation and dehydration at high temperatures. Furthermore, the extraction of cationic metals was significantly affected by solution pH. Our results suggest that chemical extraction of cationic metals under subcritical conditions may be affected by several factors, including character of metal, type of extracting reagent, existing forms of metal in the soil, temperature, and soil pH.     

Leaching Behavior of Heavy Metals and Transformation of Their Speciation in Polluted Soil Receiving Simulated Acid Rain

Heavy metals that leach from contaminated soils under acid rain are of increasing concern. In this study, simulated acid rain (SAR) was pumped through columns of artificially contaminated purple soil. Column leaching tests and sequential extraction were conducted for the heavy metals Cu, Pb, Cd, and Zn to determine the extent of their leaching as well as to examine the transformation of their speciation in the artificially contaminated soil columns. Results showed that the maximum leachate concentrations of Cu, Pb, Cd, and Zn were less than those specified in the Chinese Quality Standards for Groundwater (Grade IV), thereby suggesting that the heavy metals that leached from the polluted purple soil receiving acid rain may not pose as risks to water quality. Most of the Pb and Cd leachate concentrations were below their detection limits. By contrast, higher Cu and Zn leachate concentrations were found because they were released by the soil in larger amounts as compared with those of Pb and Cd. The differences in the Cu and Zn leachate concentrations between the controls (SAR at pH 5.6) and the treatments (SAR at pH 3.0 and 4.5) were significant. Similar trends were observed in the total leached amounts of Cu and Zn. The proportions of Cu, Pb, Cd, and Zn in the EXC and OX fractions were generally increased after the leaching experiment at three pH levels, whereas those of the RES, OM, and CAR fractions were slightly decreased. Acid rain favors the leaching of heavy metals from the contaminated purple soil and makes the heavy metal fractions become more labile. Moreover, a pH decrease from 5.6 to 3.0 significantly enhanced such effects.     

Heavy metal contamination and health risk assessment in soil-rice system near Xinqiao mine in Tongling city,Anhui province,China

In this study, paddy soil and rice grain samples were collected from the vicinity around the Xinqiao mine in Tongling, China to test for the presence of heavy metals (Cd, Ni, Cr, Cu, Zn, and Pb) in soil-rice system. Results indicated that the soil samples were primarily contaminated with Cd and Cu and followed with Zn and Pb. In rice grains, Cd, Cu, and Cr concentrations exceeded recommended guidelines. However, the regional distribution of heavy metals in rice grains and soil was inconsistent. The bioaccumulation factor of heavy metals in rice grains decreased in the order of Cd > Zn > Cu > Ni > Cr > Pb. The BAF was significantly positively correlated with TCLP-extractable metals and significantly negatively correlated with soil pH. However, the relationship between soil organic matter and the BAF in rice grains was complex. Health risk assessment through rice intake showed that hazard quotients of Cu and Cd were greater than 1 and could pose a considerable non-cancer health risk to adults and children; meanwhile, Cr, Ni, and Cd could pose an unacceptable cancer risk. The results indicated that the government must take measures to reduce heavy metal contents in paddy soil and rice.     

Effects of Adding Alkaline Material on the Heavy Metal Chemical Fractions in Soil under Flooded and Non-Flooded Conditions

We investigated the effect of adding an alkaline material (containing calcium carbonate and gypsum) on the immobilization of heavy metals (Cd, Cu, Pb, and Zn) in a paddy soil slightly contaminated with Cd and Zn under flooded and non-flooded conditions in the laboratory. Adding the alkaline material increased the soil pH and significantly decreased the exchangeable fraction of all of the metals, especially for Cd (>75% decrease) and Zn (ca. 90% decrease), under both flooded and non-flooded conditions. Drying the flooded soil samples increased the ratio of exchangeable fraction to the total fraction, particularly for Cd. The exchangeable fraction ratio was lower in the dried, previously flooded samples that contained the alkaline material than in the samples that did not contain the alkaline material, indicating that adding the alkaline material would be an effective way of immobilizing heavy metals during the oxidation of anoxic soils. These results show that the alkaline material can be used to immobilize heavy metals under both anoxic and oxic conditions, and that the effects of flooding and amending a paddy soil with alkaline material on the chemical forms will be different between heavy metals.     

Phytoremediation of Heavy Metals in Contaminated Water and Soil Using Miscanthus sp. Goedae-Uksae 1

The aim of this study is to characterize the heavy metal phytoremediation potential of Miscanthus sp. Goedae-Uksae 1, a hybrid, perennial, bio-energy crop developed in South Korea. Six different metals (As, Cu, Pb, Ni, Cd, and Zn) were used for the study. The hybrid grass effectively absorbed all the metals from contaminated soil. The maximum removal was observed for As (97.7%), and minimum removal was observed for Zn (42.9%). Similarly, Goedae-Uksae 1 absorbed all the metals from contaminated water except As. Cd, Pb, and Zn were completely (100%) removed from contaminated water samples. Generally, the concentration of metals in roots was several folds higher than in shoots. Initial concentration of metals highly influenced the phytoremediation rate. The results of the bioconcentration factor, translocation factor, and enrichment coefficient tests indicate that Goedae-Uksae 1 could be used for phytoremediation in a marginally contaminated ecosystem.     

表面活性剂对长柔毛委陵菜(Potentilla griffithii var. velutina)修复重金属污染的促进作用

研究了十二烷基苯磺酸钠(SDBS)、十六烷基三甲基溴化铵(CTAB)、聚乙二醇辛基苯基醚(TritonX-100)等不同离子类型的表面活性剂对水稻土中重金属的解吸效果,并采用盆栽实验研究了上述3种表面活性剂对Zn超富集植物长柔毛委陵菜(Potentilla griffithii var. velutina)的生物量、吸收和富集重金属的影响.结果表明:CTAB对水稻土中Zn、Pb、Cd和Cu的解吸效果好于SDBS和TritonX-100,而且3种表面活性剂对各重金属的解吸率大小都为Cd>Zn>Cu>Pb.3种表面活性剂促进长柔毛委陵菜叶、柄和根的生物量增加了0.2～2.5倍,并且长柔毛委陵菜各部位的生物量大小为叶>柄>根.3种表面活性剂都增加了长柔毛委陵菜各部位对Zn、Cd吸收及其叶和柄对Pb、Cu的吸收,同时显著促进Zn、Pb、Cd和Cu从植物根部向地上部转运,从而增加了Zn、Pb、Cd和Cu在长柔毛委陵菜地上部的提取量和分布以及长柔毛委陵菜对Zn、Pb、Cd和Cu的富集能力;因此3种表面活性剂都提高了长柔毛委陵菜修复重金属污染土壤的效率.