有机络合强化植物修复的环境风险研究I. EDTA对复合污染土壤中TOC和重金属动态变化的影响

采用盆栽试验研究了EDTA存在条件下的土壤溶液总有机碳(TOC)和重金属浓度的动态变化。结果表明,施用3 mmol/kg EDTA极显著地增加了土壤溶液中TOC的含量。土壤溶液TOC随培养时间呈指数曲线下降。在加入EDTA 52天后土壤溶液TOC仍然高于对照处理。施用EDTA大幅度地提高了土壤溶液Cu、Zn、Cd和Pb的浓度,这些重金属的浓度在一个月内迅速下降,以后趋向稳定。EDTA活化土壤重金属存在淋溶迁移的潜在环境风险。     

有机络合强化植物修复的环境风险研究：—Ⅰ．EDTA对复合污染土壤中TOC和重金属动态变化的影响

采用盆栽试验研究了EDTA存在条件下的土壤溶液总有机碳（TOC）和重金属浓度的动态变化。结果表明，施用3mmol/kg EDTA极显地增加了土壤溶液中TOC的含量。土壤溶液TOC随培养时间呈指数曲线下降，在加入EDTA52天后土壤溶液TOC仍然高于对照处理，施用EDTA大幅度地提高了土壤溶液Cu,Zn,Cd和Pb的浓度，这些重金属的浓度在一个月内迅速下降，以后趋向稳定。EDTA活化土壤重金属存在淋溶迁移的潜在环境风险。     

EDTA与EDDS螯合诱导印度芥菜吸取修复重金属复合污染土壤研究

盆栽试验比较研究了EDTA和易降解的EDDS对复合污染土壤中Cu、Zn、Pb、Cd的活化能力及印度芥菜对4种重金属的吸收与转运特征。结果表明:施用量相同的条件下,EDDS活化土壤Cu的能力与EDTA相当;而EDDS活化土壤Zn、Pb、Cd,尤其是活化土壤Pb、Cd的能力小于EDTA,这与两种螯合剂与不同重金属形成螯合物的稳定常数相一致。向复合污染土壤中施入3mmol/kg和6mmol/kgEDDS均可诱导印度芥菜叶中超量积累Cu。本研究中3mmol/kgEDDS的不同施用方式(单次施,分2次和4次施)对印度芥菜叶片Cu含量的影响差异不显著。各处理印度芥菜叶中的重金属浓度要远高于茎中的浓度,茎中的Cu浓度随土壤溶液Cu浓度线性增加,而叶中Cu的浓度随土壤溶液Cu浓度先增加后下降。     

乙二胺四乙酸在重金属污染土壤修复过程的降解及残留

为分析乙二胺四乙酸(ethylenediaminetetraacetic acid,EDTA)在修复重金属污染土壤中的环境风险,通过田间调查和培养试验研究EDTA在不同重金属污染土壤中的降解及其残留。田间调查结果表明,乐昌试验田EDTA施用6 a后,表层土壤及深层土壤中均没有检出EDTA残留。佛冈试验田在施用EDTA4个月后,表层土壤EDTA残留量为0.039~0.056 mmol/kg,仅为施入量的2%~5%,施用1a后土壤中未检测到EDTA。翁源试验田在EDTA施用45 d后,表层土壤中EDTA残留量约为施用量的一半,1 a后残留量为施入量的2,6%,深层土壤监测到EDTA残留,但地下水中并没有检测到EDTA,另外地下水中重金属含量并没有升高。因此,深层土壤对离子态和螯合态重金属具有较强的固定能力,可保护地下水免遭重金属的污染。培养试验结果表明,EDTA在土壤中降解遵循一级动力学方程,EDTA在赤红壤、褐土和重金属污染土壤中的降解速率常数分别为4.6×10~(-3)、1.4×10~(-2)和5.8×10~(-3),其降解的半衰期分别为71、25和53 d。EDTA在土壤中降解半衰期与土壤有机质含量和土壤阳离子交换量(cation exchange capacity)之间表现较好的相关性。微生物对EDTA在土壤中的降解具有显著的影响。总之,EDTA可在土壤中降解,建议在中国重金属污染土壤修复过程中可采用EDTA强化修复技术,EDTA的环境风险是可控的。     

不同种类有机物对污染农田土壤重金属活性的影响

为了解施用不同种类有机物对污染农田土壤重金属行为的影响,布设了田间小区试验,观察研究施用6种不同类型有机物对土壤水溶性重金属和农作物对重金属吸收等的影响。试验设7个处理,分别为对照(不施有机肥)、施新鲜水稻秸秆、新鲜鸡粪、鸡粪堆肥、新鲜猪粪、猪粪堆肥和商品有机肥,动态检测土壤中水溶性重金属含量、田面水中重金属浓度及收获水稻籽粒中重金属含量的变化。结果表明,与不施有机物的对照处理比较,施用各类有机物在试验前期均可明显提高土壤中水溶性重金属和田面水中重金属的含量,总体上以施用新鲜猪粪的最高,其次为新鲜鸡粪,施用商品有机肥的最低。土壤中水溶性重金属含量随试验时间增长逐渐下降。施用各类有机物对水稻籽粒中重金属的积累影响不明显。土壤中水溶性重金属及田面水中重金属含量均与相应的水溶性碳(DOC)浓度呈显著相关性,表明因有机物施用增加土壤中DOC浓度可能是土壤中水溶性重金属含量增加的主要原因;而不同有机物对土壤重金属活性影响的差异可能与有机物本身的分解程度及可释放DOC大小有关。但施用有机物引起的农田土壤水溶性重金属含量的增加是暂时的,对水稻生长后期籽粒中重金属积累的影响不明显。     

铜污染土壤修复的有机调控研究Ⅲ.EDTA和低分子量有机酸的效应

通过盆栽试验研究了EDTA和低分子量有机酸对土壤溶液性质、土壤铜形态变化和印度芥菜生长及铜吸收的影响。结果表明 ,施用pH6.3的EDTA溶液 ( 3mmolkg- 1 )显著地增加了土壤溶液铜 ,特别是难解离态铜的含量 ,其消长规律与土壤溶液TOC的变化相一致 ,也显著地增加土壤NH4NO3提取态和NH4OAc提取态铜量 ,但对芥菜生长没有显著影响。EDTA的加入显著地增加芥菜各组织铜浓度和铜吸收量 ,从而增加了芥菜的铜总吸收量 ,提高了植物修复效率。施用 3mmolkg- 1 pH6.3的草酸、柠檬酸或苹果酸对土壤铜含量及其形态分配和芥菜生长及铜吸收均无明显影响     

施用碳酸钙对土壤铅、镉、锌交换态含量及在大豆中累积分布的影响

在重金属复合污染的土壤中,通过施用不同水平的碳酸钙对土壤进行改良,研究土壤中Pb、Cd、Zn交换态含量的变化以及在大豆植株中的累积分布.结果表明:(1)在污染土壤中施用碳酸钙,能够降低土壤中Pb、Cd、Zn交换态含量,且随着碳酸钙施用量的增加,土壤中这3种重金属交换态含量呈明显降低趋势.在土壤中施用碳酸钙改善了大豆植株的生长状况,有效地抑制大豆植株对土壤Pb、Cd、Zn的吸收.从而减缓了重金属对大豆植株的毒害作用.(2)2.0 g/kg为碳酸钙的最佳施用量,能使大豆籽粒增产47.5%.籽粒中Pb含量降低73.0%,Cd含量降低53.8%,但在这个重金属污染矿区土壤中施用碳酸钙仍无法使籽粒中的重金属含量达到国家粮食卫生标准中Pb、Cd低于0.2 mg/kg的标准.     

可生物降解螯合剂GLDA和磷素活化剂促进东南景天提取土壤重金属的潜力

植物提取是重金属污染土壤的植物修复技术中去除重金属最具前途的方式之一。为了进一步提高植物对重金属的提取效率,向土壤施加螯合剂增加土壤重金属的可溶性,促进植物对重金属的吸收和积累,该技术被称为螯合诱导植物提取技术。EDTA（乙二胺四乙酸）由于其较强的络合能力,是目前常用和研究较多的螫合剂。但EDTA在环境中不易被生物降解,施入土壤的EDTA有着较长的残留效应,因此施用EDTA存在潜在的环境风险。     

长江三角洲地区污水污泥与健康安全风险研究 Ⅲ. 苏、杭二城市污水污泥所施土壤中Cu和Zn的释放动态及其环境风险

未经处理的污泥农业利用后,不仅会增加土壤中污染物的含量,而且会威胁人类和其他生物的健康。室内培养试验结果表明,污泥中的重金属进入土壤后,表现出先释放,后固定的变化趋势,而且随培养时间的增加,施污泥土壤中EDTA和CaCl2提取态Cu和Zn含量逐渐增加,150d时其含量达到最高。与对照处理相比,施污泥土壤中EDTA提取态Cu和Zn含量分别增加了21.4mgkg-1和26.1mgkg-1,而CaCl2提取态Cu和Zn含量分别增加了0.10mgkg-1和3.37mgkg-1。重金属不合格的污泥农业利用存在一定程度的重金属污染风险,且其风险大小与土壤类型、污泥种类和培养时间及污泥的土壤施用量等因素密切相关。选择适宜的土壤类型、污泥种类、施用时间及控制污泥施用量等,能够在一定程度上降低污泥中重金属农业利用的环境风险。     

淮南煤矿复垦区土壤腐殖质特征及其与重金属的关系

选择淮南典型煤矿复垦区不同土地利用方式下(菜地、玉米—小麦地、林地和荒地)的土壤作为研究对象,运用单因素方差分析和内梅罗综合污染指数调查了其腐殖质组成特征与重金属污染状况并探究两者间关系,为修复矿区复垦土壤提供依据。结果表明:土壤腐殖质含量、腐殖化程度和稳定性依菜地玉米—小麦地林地荒地的次序从最佳向最差过渡。不同土地利用方式下土壤胡敏素(HM)的组成不同,HM各组分有机碳含量为HMrHMiHMc;且施用有机肥土壤较不施肥土壤中HM各组分的含量明显增加。复垦区土壤中Cu和Cd含量均高于土壤背景值,Zn含量低于土壤背景值,土壤处于轻度污染状态。施用有机肥提高复垦土壤肥力的同时,需控制有机肥中重金属含量,以降低土壤重金属污染风险。     

The Effects of Short-Term Compost Application On Soil Chemical Properties and on Nutritional Status of Maize Plant

Compost may improve the soil quality and contribute to C sequestration. The short-term effects of compost application on soil properties of soil cropped with maize are reported here. Soil plots to which mature compost was added (at 50 Mg ha^?1 and 85 Mg ha^?1) were analyzed for total organic carbon (TOC), nutrients, heavy metals and other soil properties. In addition, maize plants were weighed at the end of the trial and analyzed for carbon (C), nitrogen (N), phosphorus (P) and heavy metals. The results demonstrate that soil amended with compost has an increased TOC content. The increase was proportional to the amount of compost used. At the highest dose used, compost also increased soil N and P content and the pH. Moreover, after compost application, the total heavy metal contents in soils did not increase. There was no difference between the maize yield from compost treated plots and the control plots. However, maize grains were found to be C, N and P enriched due to the increased nutrient status of the amended soil. In conclusion, the addition of mature compost improves soil properties by increasing the soil TOC content and this depends on the characteristics and the amount of compost used.     

重金属污染土壤清洗导致几种营养元素流失的研究

通过HCl、柠檬酸、EDTA这3种提取剂对Pb、Cd、Cu、Zn污染土壤的漫提试验，研究了土壤清洗洗脱重金属的效果，并探讨了土壤清洗导致K、Ca、Mg、Fe、Mn这几种营养元素的流失和有效性的改变。试验结果表明，土壤清洗能有效地洗脱土壤中的Ph、Cd、Cu、Zn，伺时也造成了土壤中K、Ca、Mg、Fe、Mn的流失，降低了其中部分营养元素的有效性。EDTA对重金属的洗脱能力大于HCl和柠檬酸。HCl漫提造成的K、Ca、Mg的流失量大于柠檬酸和EDTA，柠檬酸浸提造成的Fe流失量大于HCl和EDTA，EDTA漫提造成的Mn流失量大于HCl和柠檬酸。HCl和柠檬酸浸提降低了土壤K、Ca、Mg的有效性EDTA浸提提高了土壤K的有效性。降低了土壤Ca的有效性。在高浓度时（50mmol／L），EDTA显著地降低了土壤Mg的有效性。HCl漫提导致土壤K的有效性下降比柠檬酸严重，高浓度的EDTA浸提导致土壤Ca的有效性下降比HCl和柠檬酸严重。HCl、柠檬酸、EDTA浸提都能提高土壤中Fe的有效性．且EDTA的效应大于其它2种萃取剂；在低浓度时，3种提取剂都能提高土壤中Mn的有效性，且以柠檬酸的作用最为明显，当提取剂浓度增加时，Mn的有效性有所回落。     

重金属高污染农田土壤EDTA淋洗条件初探

通过室内振荡淋洗试验研究了乙二胺四乙酸二钠(EDTA)浓度、淋洗时间、液固比、淋洗次数对甘肃省白银市某高污染农田土壤中重金属去除效果的影响,并测定了EDTA淋洗前后土壤中重金属形态的变化。结果表明：淋洗剂浓度和液固比越高、淋洗时间越长、淋洗次数越多,对重金属的去除效果越好。在EDTA浓度为5 mmol/L、液固比为2.5、连续振荡淋洗3次、每次1 h时,对土壤中Cd、Cu、Pb、Zn 4种重金属的总去除率分别为 55.2%、21.9%、19.3% 和20.9%,其中Cd 淋洗效率最高。EDTA对土壤中交换态、碳酸盐结合态和铁锰氧化物结合态重金属的去除效果明显,但不能有效去除有机及硫化物态和残余态土壤重金属。     

添加螯合剂诱导－栽培红叶菾菜（Beta vulgaris var. cicla L.）修复铅和镉污染土壤效果的研究

以雄安新区安新县重金属污染农田土壤为供试土壤,以Cd超积累植物红叶菾菜（Beta vulgaris var. cicla L.）为供试植物,设置不同浓度EDTA和柠檬酸（0,2.5,5,7.5,10 mmol kg?1）处理进行盆栽试验,探究螯合诱导－红叶菾菜修复Cd、Pb污染土壤的可行性。结果表明:（1）与对照相比,添加EDTA螯合剂使红叶菾菜生长及生物量均受到抑制,一定浓度柠檬酸处理能显著促进植物生长,5 mmol kg?1柠檬酸处理对植物株高、茎粗及生物量与对照相比的上升比例分别为4.52%、44.07%和50%;（2）添加EDTA螯合剂后土壤中Cd、Pb有效态含量相比对照分别提高了108.61% ~ 235.39%、67.98% ~ 224.16%,柠檬酸处理后土壤Cd、Pb有效态含量最大提高了180.07%、186.01%,EDTA对土壤重金属的活化效率显著高于柠檬酸;（3）通过对红叶菾菜地上部Cd、Pb含量及富集系数比较发现,EDTA更能促进红叶菾菜对Pb的吸收,柠檬酸更能促进红叶菾菜对Cd的吸收;（4）螯合剂处理后土壤中铵态氮、有效磷、速效钾含量显著增加。就本文试验条件、供试材料而言,螯合诱导－红叶菾菜修复铅镉复合污染土壤是可行的。     

间作条件下螯合剂对龙葵和大叶井口边草吸收重金属的影响

用室内土培试验方法,在采自田间的Pb、Cd和As复合污染土壤中单作或间作龙葵和大叶井口边草条件下,筛选出修复Pb-Cd-As复合污染土壤较好的种植方式为间作。进一步在间作方式下,研究了外源添加不同浓度EDDS（乙二胺二琥珀酸）、NTA（氨三乙酸）和EDTA（乙二胺四乙酸）对植物吸收Pb、Cd和As的影响。结果表明,间作显著促进了龙葵地上部对Cd的吸收量和大叶井口边草地上部对As的吸收量,间作龙葵地上部吸收Cd和大叶井口边草地上部吸收As含量分别是单作龙葵和大叶井口边草的1.3倍和1.4倍,说明间作龙葵和大叶井口边草比单作更有利于修复Pb-Cd-As复合污染土壤。间作条件下,大叶井口边草对螯合剂的耐性比龙葵更强。3、6、12mmol.kg-1EDTA能极显著增加土壤中Pb、Cd有效态含量,从而促进龙葵地上部对Pb吸收和大叶井口边草地上部对Pb、Cd吸收。EDTA比NTA具有更强的提高土壤Pb、Cd有效态的能力,但对土壤As有效态促进作用与EDTA相比,NTA效果极显著,1.5、3mmol.kg-1NTA处理极显著提高土壤As有效态含量及促进龙葵和大叶井口边草地上部对As吸收。     

污泥混配土淋溶液中pH、氮磷及重金属含量的动态变化

以北京市大兴区庞各庄镇污水处理厂的堆肥污泥、生污泥和通州区的熟土为对象,探讨污泥混配土淋溶液中相关指标的动态变化.结果表明,生污泥、堆肥污泥和熟土混配后可降低土壤pH值,增加土壤全氮、全磷含量,同时也增加了土壤中重金属As、Cd、Ni、Cu、Ph的含量,生污泥系列淋滤液中Pb对地下水造成污染的可能性最大;堆肥污泥系列淋滤液中给地下水带来污染可能性最大的因子是As.但各处理中重金属的污染程度都很低,基本符合国家第II类地下水水质标准,因此淋滤液中的重金属基本不会对地下水造成污染.     

Soil microorganisms and the growth of Lupinus albus on a high metal soil in the presence of EDTA

A pot experiment was designed with the objective of determining whether the presence of ethylenediaminetetraacetic acid (EDTA) and the resulting mobilization of heavy metals have any affect on: (i) soil microorganisms, (ii) growth of L. albus, and (iii) microbial colonization of roots. There was no effect of the different treatments on the contents of soil microbial biomass C and microbial biomass N. Increasing addition of EDTA to soil led to proportionate increases in extractable C and N, being roughly equivalent to the added amount. Increasing EDTA addition to soil led also to a proportionate increase in mobile heavy metals. Plant height, total amount of shoot and root C were not affected by EDTA addition. Fungal ergosterol in the lupine roots showed a 5- to 8-fold increase in the 0.1 and 0.2% EDTA treatments in comparison with the control. In contrast, EDTA addition did not affect fungal glucosamine or bacterial muramic acid concentrations in the lupine roots. Increasing EDTA addition to soil led also to a proportionate increase in the metal concentrations in the lupine shoots. The concentrations of heavy metals in the lupine shoots and in the NH₄NO₃ soil extracts were all highly significantly correlated.     

Influence of inorganic and organic fertilization on soil microbial biomass, metabolic quotient and heavy metal bioavailability

 We studied the long-term effects (12 years) of municipal refuse compost addition on the total organic carbon (TOC), the amount and activity of the microbial biomass (soil microbial biomass C, B_C and metabolic quotient qCO₂) and heavy metal bioavaiability in soils as compared to manuring with mineral fertilizers (NPK) and farmyard manure (FYM). In addition, we studied the relationships between among the available fraction [Diethylenetriaminopentacetic acid (DTPA) extractable] of heavy metals and their total content, TOC and B_C. After 12 years of repeated treatments, the TOC and B_C of control and mineral fertilized plots did not differ. Soils treated with FYM and composts showed a significant increase in TOC and B_C in response to the increasing amounts of organic C added. Values of the B_C/TOC ratio ranged from 1.4 to 2, without any significative differences among soil treatments. The qCO₂ increased in the organic-amended soil and may have indicated microbial stress. The total amounts of metals in treated soils were lower than the levels permitted by the European Union in agricultural soils. DTPA-extractable metals increased in amended soils in response to organic C. A multiple regression analysis with stepwise selection of variables was carried out in order to discriminate between the influence exerted on DTPA-extractable metals by their total content, TOC and B_C. Results showed that each metal behaved quite differently, suggesting that different mechanisms might be involved in metal bioavailability Received: 31 October 1997     

Water-soluble organic materials in paddy soil ecosystem

Abstract

A column experiment was conducted to analyse the composition of organic materials in the leachate from the plow layer and their fate in the subsoil. Water-soluble organic materials in the leachate were fractionated by insoluble polyvinylpyrrolidone (PVP) and ion exchange resins. The content of total organic carbon (TOC) in the leachate increased by the addition of rice straw (RS) to the plow layer soil sample. The leachate contained a constant amount of PVP-adsorbed Fraction, while that of the PVP-non-adsorbed Fraction changed during the 45 day incubation period. In the fractionation using ion exchange resins, the fraction adsorbed onto the anion exchange resin was the major one.

By the connection of a subsoil column to the plow layer soil column with RS, the TOC content in the leachate decreased by percolation into the subsoil sample. In the Anjo soil sample (Yellow Soil), the decrease occurred throughout the incubation period, and about 90% of the PVP-adsorbed Fraction in the leachate decreased by percolation into the subsoil sample. In the Fukushima soil sample (Gray Lowland Soil), the TOC content decreased in the early and middle periods of incubation, while in the late period the decrease was negligible. This decrease of the TOC content by percolation into the subsoil sample was mainly due to retention in the subsoil sample of the Anjo soil, while in the Fukushima soil sample it was due to decomposition and retention. It was considered that easily decomposable organic materials like organic acids were decomposed in the early to middle periods of incubation, while in the late period the contents of such substances in the leachate from the plow layer soil sample with RS were small and the decrease of TOC was negligible.