某生物质电厂周边农田土壤中多环芳烃污染特征及生态安全评价

为了解与评价某生物质电厂周边农田土壤多环芳烃的污染状况,按照点源扇形布点原则,在电厂周边4个方位不同距离布点,在远离电厂区域设置对照点.参照《土壤环境监测技术规范》(HJ/T 166—2004)采样,共采集25个农田土壤样品.取经过处理的样品5.00 g,用乙腈超声提取、浓缩后,HPLC法测定15种PAHs的含量.描述其空间分布特征,采用特征污染物分析、环数分析、异构体比值分析及聚类分析等方法解析污染来源,运用荷兰分级标准评价法进行生态安全评价.结果显示生物质电厂周边农田土壤中15种PAHs总量为311μg·kg~(-1)(204～576μg·kg~(-1)),TEQ(BaP)为21.9μg·kg~(-1)(4.39～58.1μg·kg~(-1)),明显高于对照区的193μg·kg~(-1)(76.1～329μg·kg~(-1))和12.7μg·kg~(-1)(0.499～31.9μg·kg~(-1)).在常年主导风向下风向,BaP、PAHs总量和TEQ(BaP)随烟囱距离的增加呈抛物线趋势分布,最大值在距电厂1000 m处.生物质电厂周边农田土壤中高环PAHs组分高于对照区和燃煤电厂周边,生物质燃烧是该区域PAHs的主要来源.生物质电厂周边农田土壤中BaP、∑PAHs和TEQ(BaP)高于燃煤电厂和医疗垃圾焚烧厂,存在不容忽视的生态风险.     

江西典型钨矿开采对周边环境稀土元素含量的影响

研究了江西省典型钨矿区开采和冶炼对周边农田土壤、水体和白菜中稀土元素含量的影响.结果表明:钨矿区周边农田土壤中稀土元素含量范围在256~459 mg·kg~(-1)之间,平均值为373 mg·kg~(-1),土壤中稀土含量均高于江西省和全国土壤稀土元素含量的背景值,分别是它们的1.77倍和1.99倍.矿区河水中稀土元素浓度达3086μg·L~(-1),为对照区河水稀土元素浓度的497倍.矿区15个样地白菜稀土元素含量范围为773~5992μg·kg~(-1),平均值为3007μg·kg~(-1),为非矿区白菜稀土元素含量的5.22倍,矿区白菜稀土元素含量远超过我国蔬菜卫生标准稀土元素含量的限值(0.70 mg·kg~(-1)),说明钨矿开采冶炼已造成周边环境的污染,并对矿区居民身体健康构成潜在威胁.     

盐渍化条件下污灌区土壤重金属的释放特征

以受盐渍化和重金属双重胁迫的天津污灌区土壤为研究对象,通过径流实验和淋溶实验,探讨盐渍化土壤重金属的释放特征及对水质安全的影响.研究的盐分种类为污灌区土壤盐渍化进程中的主要盐分Na Cl,设置的盐度梯度为7个,添加质量分数为0(CK)~5%,污染土壤中Cd、Pb和Hg含量分别为2.21、234.1和0.601 mg·kg~(-1).结果表明,(1)不同盐度处理下产流所需时间为(51'25″±15″),盐度对径流产流时间影响不显著;(2)随着Na Cl盐度梯度的提高,土壤径流和淋溶液中Cd、Pb和Hg的累计释放量均显著上升.Cd累计释放量从CK的53.40μg·kg~(-1)(径流)和55.63μg·kg~(-1)(淋溶)分别提高到5%Na Cl盐度处理的122.56μg·kg~(-1)(径流)和135.79μg·kg~(-1)(淋溶),Pb的累计释放量从CK的168.30μg·kg~(-1)(径流)和94.44μg·kg~(-1)(淋溶)分别提高到5%Na Cl盐度处理的340.68μg·kg~(-1)(径流)和201.93μg·kg~(-1)(淋溶),Hg的累计释放量从CK的39.66μg·kg~(-1)(径流)和9.60μg·kg~(-1)(淋溶)分别提高到5%Na Cl处理的89.37μg·kg~(-1)(径流)和11.97μg·kg~(-1)(淋溶).同时,径流及淋溶液中可溶态重金属含量显著上升,颗粒态含量有所下降,其所占比例也显著下降.Cl-含量与重金属累计释放量之间关系可以用线性或对数模型拟合.(3)高盐度处理下径流和淋出液中Cd浓度超过地下水水质Ⅲ类标准,对环境及地下水存在一定威胁;径流和淋溶前期Pb浓度超过Ⅲ类标准;径流和淋溶过程中Hg浓度均超过Ⅲ类标准,风险较高.本研究结果表明高强度降雨强度下污染农田土壤重金属释放风险不可忽视.     

铅锌冶炼区农田土壤中多环芳烃污染特征、源解析和风险评价

采用快速溶剂萃取(ASE)、凝胶渗透色谱净化(GPC)协同高效液相色谱(HPLC)检测方法,分析贵州省典型铅锌冶炼区赫章县41个表层农田土壤样品中16种优控多环芳烃(PAHs)的含量水平,并对其污染特征、来源和生态风险进行了分析.结果表明:典型铅锌冶炼区妈姑镇农田土壤∑PAHs的含量范围为196~11592μg·kg~(-1),算术均值和中位值分别为1500μg·kg~(-1)和780μg·kg~(-1),妈姑镇高含量的∑PAHs积累可能与当地长时间的铅锌冶炼活动有关.PAHs组分特征表现出以2~3环和4环多环芳烃为主.根据荷兰土壤干预值,妈姑镇农田土壤96.6%受到了不同程度的污染,其中,轻微污染、中度污染和重度污染所占比例分别为31.0%、24.1%和41.5%.研究区域PAHs的主要来源为煤和生物质的不完全燃烧及石油源.妈姑镇的新厂村、何家冲村、平桥组、拱桥村及赫章县的达依乡采样点土壤中PAHs的TEQBap10超过了荷兰土壤干预值规定的TEQBap10限值33.0μg·kg~(-1),说明赫章县、尤其是赫章县典型铅锌冶炼区妈姑镇农田土壤已受到PAHs的污染,存在潜在的生态风险.     

东新开河小流域土壤汞空间分布特征及风险评价研究

研究选择松花江三级支流东新开河小流域,在其干流及支流选定了13个河流断面,测定并讨论了断面两侧岸带土壤总汞的空间分布、污染现状和生态风险。结果表明,小流域内土壤汞含量为14μg·kg~(-1)～499μg·kg~(-1),均值为(78±11.87)μg·kg~(-1),其中超过长春市土壤背景值(40μg·kg~(-1))的采样点占比为63.8%。流域总体表现为无汞污染(污染指数为-0.11),最高处汞污染为强(污染指数为3.06)。流域总体中有中度潜在生态风险(78),潜在生态风险最高处为极强(499)。     

养殖场周边土壤-蔬菜系统磺胺类药物残留及风险评价

采集了新乡市周边不同种类、规模的养殖场施用粪便的土壤以及蔬菜样品,并采用高效液相-荧光分析法测定了样品中磺胺嘧啶、磺胺间甲氧嘧啶和磺胺甲恶唑这3种主要磺胺类药物的残留情况.结果表明,3种磺胺类药物在土壤和蔬菜中的总含量范围分别为7.60~176.26μg·kg~(-1)和ND~32.70μg·kg~(-1),平均含量分别为70.73μg·kg~(-1)和7.08μg·kg-1.土壤中药物平均残留量均低于兽药国际协调委员会规定的生态毒害效应触发值(100μg·kg~(-1)).不同种类蔬菜中药物的残留量不同,青菜、油麦菜、白菜和大葱这4种蔬菜中3种磺胺类药物的平均残留量最高.所有蔬菜样品中3种药物的残留水平未超过磺胺类药物的日允许摄入量,但仍不能忽略人类长期食用所导致人体抗药细菌或基因的形成.     

不同土地利用类型的土壤中多环芳烃的纵向迁移特征

为研究城镇化过程中不同土地利用类型土壤中多环芳烃(PAHs)的纵向迁移特征,在快速进行城镇化建设的沈阳东部地区选择了3种不同土地利用类型(城市用地、耕地及林地)的5个土壤剖面(0～1 m),分析了土壤剖面层中PAHs的残留特征,讨论了影响PAHs纵向分布和迁移的因素以及土壤PAHs的来源.结果表明,5个采样点土壤表层ΣPAHs的含量为:城市1号点513. 19～12 689. 04μg·kg~(-1)、旱田点36. 18～7 196. 10μg·kg~(-1)、水田点70. 92～747. 53μg·kg~(-1)、城市2号点19. 39～636. 47μg·kg~(-1)和林地点4. 79～349. 24μg·kg~(-1). PAHs在城市用地和林地中主要被截留在0～30 cm浅层土壤中,在耕地可以迁移至较深的土壤层;高环数PAHs在浅层土壤层中所占比例较大,深层土壤低环数占比较高;土壤有机质与PAHs分布呈显著正相关,PAHs的理化属性对其迁移能力有一定影响;源解析表明,研究区域的PAHs主要来源于工业活动和交通等燃烧,部分低环数PAHs来自于石油产品输入.     

长三角典型城郊不同土地利用土壤抗生素组成及分布特征

阐明不同土地利用条件下土壤抗生素的组成及其分布特征对于正确客观认识抗生素的空间扩散迁移过程具有重要意义.本研究选取长三角典型城郊地区宁波樟溪流域,在流域内根据土地利用、地形特征等布设样点采集0~40 cm深度土壤样品,利用固相萃取和HPLC-MS/MS测定土壤中抗生素含量,研究不同土地利用类型中土壤抗生素的组成及其含量,以及土壤抗生素在城郊地区的空间分布特征,并对其来源和影响因素进行了初步探讨.研究结果表明,流域内土壤抗生素分布具有较大的空间差异性,抗生素含量范围为0.05~395.55μg·kg~(-1).不同土地利用类型土壤中抗生素含量与组成差异较大,农田土壤抗生素含量范围0.35~395.55μg·kg~(-1),主要成分为四环素类(TCs),约占81.45%;林地土壤抗生素含量显著低于农田,含量范围为0.07~3.65μg·kg~(-1),主要成分为喹诺酮类(QNs),约占70.04%;园地土壤抗生素含量与组成介于两者之间,主要包括TCs(67.63%)和QNs(29.55%),含量范围为0.05~26.43μg·kg~(-1),显著低于农田,但与林地之间没有显著差异.本研究选用距城镇距离、距道路距离、海拔以及土壤C/N来表征人类活动的影响,数据分析表明土壤抗生素含量随4个指标的增加而降低,同时Spearman相关分析表明选取的4个指标均对土壤抗生素总含量具有显著的负影响(P0.01).研究结果表明典型城郊土壤抗生素污染主要受土地利用的影响,其含量则随人类活动强度的减弱而降低.     

大兴安岭南瓮河湿地类型对土壤中甲基汞分布的影响

甲基汞(methylmercury,MeHg)是所有汞(Hg)的化合物中毒性最强的有机物,其毒性远远大于无机Hg. MeHg可能通过食物链的传递进入人体,威胁人类健康.本研究以大兴安岭南瓮河国家自然保护区为研究对象,分析了中位沼泽、低位沼泽、岛状林、森林土4种湿地类型土壤样品MeHg含量分布差异以及土壤性质对MeHg含量的影响.结果表明:(1)总汞(THg)与MeHg含量变化趋势不一致,THg含量的高低顺序为:岛状林[(138. 76±101. 97) mg·kg~(-1)]森林土[(117. 57±32. 44) mg·kg~(-1)]低位沼泽[(71. 8±1. 42) mg·kg~(-1)]中位沼泽[(65. 11±26. 69) mg·kg~(-1)],而MeHg含量高低顺序为:岛状林[(1. 14±1. 15)μg·kg~(-1)]中位沼泽[(0. 87±1. 06)μg·kg~(-1)]低位沼泽[(0. 28±0. 06)μg·kg~(-1)]森林土[(0. 1±0. 05)μg·kg~(-1)];(2)岛状林和中位沼泽中MeHg的含量较高且随采样位点波动较大,低位沼泽和森林土中MeHg的含量较低,每个取样点之间变化较小;(3)沼泽湿地形成的时间越长,MeHg的含量越多,即中位沼泽[(0. 87±1. 06)μg·kg~(-1)]低位沼泽[(0. 28±0. 06)μg·kg~(-1)];土壤p H与MeHg的含量呈显著正相关(P 0. 05);含水率(WC)、有机质(OM%)、总碳(C%)、总汞(THg)含量在中位沼泽地区与MeHg含量呈显著的线性关系(P 0. 05);土壤p H、铵态氮(NH+4-N)含量在岛状林地区与MeHg含量呈显著的线性关系(P 0. 05).本研究阐明了不同湿地生态系统MeHg的分布特点及其影响因素,为全面评价湿地生态系统中MeHg积累及其环境风险提供了数据支撑.     

水泥粉尘对农田土壤污染的环境磁学响应

为了探索水泥工业生产与厂周围农田土壤环境变迁之间的关系,在安徽省凤阳县水泥工业区周围农田内采集了麦地土壤和3条测线(EW、N-W、N-S)上稻田土壤,对土壤样品及水泥粉尘的磁学参数和金属元素(Al、Fe、K、Ca、Mg、Na、Cr、Ba、Mn、Zn)含量进行了测量.结果显示,两类土壤样品的磁学性质主要由磁铁矿控制,磁性矿物含量高于土壤母质参考值、低于水泥粉尘,磁性矿物粒径介于土壤母质和水泥粉尘之间.麦地土壤样品中Ca、Zn含量的平均值(85.4 g·kg~(-1)、101.0 mg·kg~(-1))高于3条测线上稻田土壤的平均值(10.6 g·kg~(-1)、51.0 mg·kg~(-1)(E-W);11.0g·kg~(-1)、68.0 mg·kg~(-1)(N-S);8.9 g·kg~(-1)、55.6 mg·kg~(-1)(N-W)),且大幅高于土壤母质参考值(5.9 g·kg~(-1)、29.9 mg·kg~(-1)),但低于水泥粉尘的值(344.0 g·kg~(-1)、110.3 mg·kg~(-1)).内梅罗指数PN结果显示,麦地土壤样品呈现出重度污染(5PN20),3条测线上稻田土壤样品呈现出轻度污染到中度污染的特征(1PN3),离水泥厂越近污染越严重.所有土壤样品的磁学参数χ、SIRM、χARM与PN存在显著正相关关系(r=0.918、0.944、0.968).因此,磁学参数χ、SIRM、χARM可以作为农田土壤被水泥粉尘污染程度的指示.     

Toxic effects of acetochlor, methamidophos and their combination on nifH gene in soil

Toxic effects of two agrochemicals on nifH gene in agricultural black soil were investigated using denaturing gradient gel electrophoresis （DGGE） and sequencing approaches in a microcosm experiment. Changes of soil nifH gene diversity and composition were examined following the application of acetochlor, methamidophos and their combination. Acetochlor reduced the nifH gene diversity （both in gene richness and diversity index values） and caused changes in the nifH gene composition. The effects of acetochlor on nifH gene were strengthened as the concentration of acetochlor increased. Cluster analysis of DGGE banding patterns showed that nifH gene composition which had been affected by low concentration of acetochlor （50 mg/kg） recovered firstly. Methamidophos reduced nifH gene richness that except at 4 weeks. The medium concentration of methamidophos （150 mg/kg） caused the most apparent changes in nifH gene diversity at the first week while the high concentration of methamidophos （250 mg/kg） produced prominent effects on nifH gene diversity in the following weeks. Cluster analysis showed that minimal changes of nifH gene composition were found at 1 week and maximal changes at 4 weeks. Toxic effects of acetochlor and methamidophos combination on nifH gene were also apparent. Different nifH genes （bands） responded differently to the impact of agrochemicals： four individual bands were eliminated by the application of the agrochemicals, five bands became predominant by the stimulation of the agrochemicals, and four bands showed strong resistance to the influence of the agrochemicals. Fifteen prominent bands were partially sequenced, yielding 15 different nifH sequences, which were used for phylogenetic reconstructions. All sequences were affiliated with the alpha- and beta-proteobacteria, showing higher similarity to eight different diazotrophic genera.     

Arsenic uptake by arbuscular mycorrhizal maize （Zea mays L.） grown in an arsenic-contaminated soil with added phosphorus

The effects of arbuscular mycorrhizal (AM) fungus (Glomus mosseae) and phosphorus (P) addition (100 mg/kg soil) on arsenic (As) uptake by maize plants (Zea mays L.) from an As-contaminated soil were examined in a glasshouse experiment.Non-mycorrhizal and zero-P addition controls were included.Plant biomass and concentrations and uptake of As,P,and other nutrients,AM colonization,root lengths,and hyphal length densities were determined.The results indicated that addition of P significantly inhibited root colonization and development of extraradical mycelium.Root length and dry weight both increased markedly with mycorrhizal colonization under the zero-P treatments,but shoot and root biomass of AM plants was depressed by P application.AM fungal inoculation decreased shoot As concentrations when no P was added,and shoot and root As concentrations of AM plants increased 2.6 and 1.4 times with P addition,respectively.Shoot and root uptake of P,Mn,Cu,and Zn increased,but shoot Fe uptake decreased by 44.6%,with inoculation, when P was added.P addition reduced shoot P,Fe,Mn,Cu,and Zn uptake of AM plants,but increased root Fe and Mn uptake of the nonmycorrhizal ones.AM colonization therefore appeared to enhance plant tolerance to As in low P soil,and have some potential for the phytostabilization of As-contaminated soil,however,P application may introduce additional environmental risk by increasing soil As mobility.     

Distribution and ecological effect of mercury in Laogang landfill, Shanghai, China

Laogang landfill near Shanghai is the largest landfill in China, and receives about 10000 t of daily garbage per day, Samples of topsoil and plants were analyzed to evaluate mercury pollution from the landfill. For topsoil samples, there were significant correlations among total mercury （HgT）, combinative mercury （Hgc） and gaseous mercury （HgG）, and content of total organic carbon （TOC）, but, no significantly relationship was found between Hg content and filling time. Hg content changes in vertical profiles with time showed that the average Hgv of profiles 1992, 1996, and 2000 was similar, but their average HgG was quite different. HgT was significantly correlated with Hgc in profile 1992 and 2000, and Hgv was significantly correlated with Hg6 in profile 1996. HgG/Hgv ratio in profile samples decreased in the order of （HgG,/HgT）1992〉（HgG/HgT）1996〉〉（HgG/HgT）2000. A simple outline of Hg release in landfill could be drawn： with increasing of filling time, degradation undergoes different biodegradation, accordingly, gaseous mercury goes through small, more, and small proportion to total mercury. Distribution of Hg in plants was inhomogeneous, following the order of leaf〉root〉stem. The highest value of leaf may be associated with higher atmospheric Hg from landfill. Ligneous plants （e.g. Phyllostachys glanca, Prunus salicina and Ligustrum lucidum） are capable of enriching more Hg than herbaceous plants.     

EDTA-enhanced phytoremediation of lead contaminated soil by Bidens maximowicziana

Phytoremediation is a potential cleanup technology for the removal of heavy metals from contaminated soils.Bidens maximowicziana is a new Pb hyperaccumulator,which not only has remarkable tolerance to Pb but also extraordinary accumulation capacity for Pb.The maximum Pb concentration was 1509.3 mg/kg in roots and 2164.7 mg/kg in overground tissues.The Pb distribution order in the B. maximowicziana was:leaf>stem>root.The effect of amendments on phytoremediation was also studied.The mobility of soil Pb and the Pb concentrations in plants were both increased by EDTA application.Compared with CK(control check),EDTA application promoted translocation of Pb to overground parts of the plant.The Pb concentrations in overground parts of plants was increased from 24.23-680.56 mg/kg to 29.07-1905.57 mg/kg.This research demonstrated that B.maximowicziana appeared to be suitable for phytoremediation of Pb contaminated soil,especially,combination with EDTA.     

Potential of plant polyphenol oxidases in the decolorization and removal of textile and non-textile dyes

In this study an effort has been made to use plant polyphenol oxidases; potato （Solanum tuberosum） and brinjal （Solanum melongena）, for the treatment of various important dyes used in textile and other industries. The ammonium sulphate fractionated enzyme preparations were used to treat a number of dyes under various experimental conditions. Majority of the treated dyes were maximally decolorized at pH 3.0. Some of the dyes were quickly decolorized whereas others were marginally decolorized. The initial first hour was sufficient for the maximum decolorization of dyes. The rate of decolorization was quite slow on long treatment of dyes. Enhancement in the dye decolorization was noticed on increasing the concentration of enzymes. The complex mixtures of dyes were treated with both preparations of polyphenol oxidases in the buffers of varying pH values. Potato polyphenol oxidase was significantly more effective in decolorizing the dyes to higher extent as compared to the enzyme obtained from brinjal polyphenol oxidase. Decolorization of dyes and their mixtures, followed by the formation of an insoluble precipitate, which could be easily removed simply by centrifugation.     

Decomposition of alachlor by ozonation and its mechanism

Decomposition and corresponding mechanism of alachlor, an endocrine disruptor in water by ozonation were investigated. Results showed that alachlor could not be completely mineralized by ozone alone. Many intermediates and final products were formed during the process, including aromatic compounds, aliphatic carboxylic acids, and inorganic ions. In evoluting these products, some of them with weak polarity were qualitatively identified by GC-MS. The information of inorganic ions suggested that the dechlorination was the first and the fastest step in the ozonation of alachlor.     

Enzymatic oxidation of aqueous pentachlorophenol

The influence of the nonionic surfactant Tween 80 on pentachlorophenol （PCP） oxidation catalyzed by horseradish peroxidase was studied. The surfactant was tested at concentrations below and above its critical micelle concentration （CMC）. Enhancement of PCP removal was observed at sub-CMCs. The presence of Tween 80 in the reaction mixture reduced enzyme inactivation which occurred through a combination of free radical attack and sorption by precipitated products. A simple first-order model was able to simulate time profiles for enzyme inactivation in the presence or absence of Tween 80. At supra-CMCs, the surfactant caused noticeable reductions in PCP removal, presumably through micelle partitioning of PCP which precluded the hydrophobic PCP molecule from interacting with the enzyme.     

Removal of heavy metals from sewage sludge by low costing chemical method and recycling in agriculture

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Organochlorine pesticides in soils under different land usage in the Taihu Lake region, China

A field study was conducted in the Taihu Lake region, China in 2004 to reveal the organochlorine pesticide concentrations in soils after the ban of these substances in the year 1983. Thirteen organochlorine pesticides (OCPs) were analyzed in soils from paddy field, tree land and fallow land. Total organochlorine pesticide residues were higher in agricultural soils than in uncultivated fallow land soils. Among all the pesticides, ΣDDX (DDD, DDE and DDT) had the highest concentration for all the soil samples, ranging from 3.10 ng/g to 166.55 ng/g with a mean value of 57.04 ng/g and followed by ΣHCH, ranging from 0.73 ng/g to 60.97 ng/g with a mean value of 24.06 ng/g. Dieldrin, endrin, HCB and α-endosulfan were also found in soils with less than 15 ng/g. Ratios of p,p'-(DDD DDE)/DDT in soils under three land usages were: paddy field ＞ tree land ＞ fallow land, indicating that land usage inlfuenced the degradation of DDT in soils. Ratios of p,p'-(DDD DDE)/DDT ＞1, showing aged residues of DDTs in soils of the Taihu Lake region. The results were discussed with data from a former study that showed very low actual concentrations of HCH and DDT in soils in the Taihu Lake region, but according to the chemical half-lives and their concentrations in soils in 1980s, the concentration of DDT in soils seemed to be underestimated. In any case our data show that the ban on the use of HCH and DDT resulted in a tremendous reduction of these pesticide residues in soils, but there are still high amounts of pesticide residues in soils, which need more remediation processes.     

Single and joint effects of pesticides and mercury on soil urease

The influence of two pesticides including chlorimuron-ethyl and furadan and mercury （Hg） on urease activity in 4 soils （meadow burozem and phaeozem） was investigated. The soils were exposed to various concentrations of the two pesticides and Hg individually and simultaneously. Results showed that there was a close relationship between urease activity and organic matter content in soil. Chlorimuron-ethyl and furadan could both activate urease in the 4 soils. The maximum increment of urease activity by chlorimuronethyl was up to 14%-18%. There was almost an equal increase （up to 13%-21%） in the urease activity by furadan. On the contrary, Hg markedly inhibited soil urease activity. A logarithmic equation was used to describe the relationship （P〈0.05） between the concentration of Hg and the activity of soil urease in the 4 tested soils. Semi-effect dose （ED50） values by the stress of Hg based on the inhibition of soil urease in the 4 soils were 88, 5.5, 24 and 20 mg/kg, respectively, according to the calculation of the corresponding equations. The interactive effect of chlorimuron-ethyl or furadan with metal Hg on soil urease was mainly synergic at the highest tested concentrations.