渭河陕西段浮游植物群落结构时空变化与影响因子分析

浮游植物是水生态系统的初级生产者,其群落结构与水环境密切相关.为了解渭河陕西段浮游植物群落结构时空格局及其与环境因子的关系,更好地进行水资源和水生态保护,于2017年9月—2018年4月在丰水期和枯水期对该河段设定的9个研究断面,27个采样点位进行浮游植物群落结构和水环境因子调查监测,共检出浮游植物8门69种,群落结构分析表明,枯水期浮游植物种类数高于丰水期.浮游植物细胞密度和生物量变化分别为84.9×10⁴~3868.3×10⁴ cells·L^-1、0.268~20.978 mg·L^-1,丰水期平均密度（1490.0×10⁴ cells·L^-1）和平均生物量（7.864 mg·L^-1）显著大于枯水期（354.8×10⁴ cells·L^-1、1.152 mg·L^-1）.优势种分别为6种和8种,主要以绿藻门和硅藻门为主.浮游植物Shannon-Wiener指数（H''）、Pielou均匀度指数（J）、Margalef丰富度指数（d）均表明丰水期浮游植物多样性高于枯水期,9个采样断面的水质总体评价呈现出无污染或轻度污染至中轻污染状态.典范对应分析（CCA）排序结果表明,影响枯水期浮游植物群落结构的主要环境因子为总磷（TP）、pH和总溶解性固体（TDS）,TP和高锰酸盐指数（COD_Mn）是影响丰水期浮游植物群落结构的主要环境因子.     

城市闸控河流浮游植物群落结构特征及影响因素

以典型城市闸控河流—南京市西北护城河为研究对象,通过开展2019—2020年4个不同季度的水环境及浮游植物采样调查,综合分析了城市闸控河流浮游植物群落结构的时空变化特征,探讨了环境因子、水位调控和护岸类型等对浮游植物群落结构的影响.结果显示,南京市西北护城河四季共采集到浮游植物7门90种,主要隶属于硅藻门（Bacillariophyta）和绿藻门（Chlorophyta）,夏季和春季物种数多,冬季和秋季物种数少.浮游植物密度为2.1×10³~5.47×10⁶ cells·L^-1,生物量为2×10^-3~6.28 mg·L^-1;浮游植物Shannon-Wiener多样性指数为0.60~2.35,Pielou均匀度指数为0.17~0.59,处于中度污染状态.西北护城河浮游植物群落结构不仅受水温及营养盐等环境因子影响,还与水位调控及河流护岸类型密切相关.高频率水位调控能有效减少有害藻类的聚集爆发,生态护岸保留了自然河流中的生态循环系统,可为浮游植物提供更有利的生境条件.     

苏州平原河网区浅水湖泊冬夏季浮游植物群落与环境因子的典范对应分析

2005年12月和2006年6月对苏州平原河网区57个浅水湖泊的浮游植物群落进行了调查,共检出浮游植物8门62属73种,浮游植物主要由绿藻、硅藻和蓝藻组成.冬季浮游植物平均丰度为254.88×10⁴cells·L^-1,硅藻门丰度占总丰度的62.3％;夏季浮游植物平均丰度为2 704.28×10⁴cells·L^-1,蓝藻门丰度达93.5％.运用典范对应分析(canonical correspondence analysis, CCA)对调查范围内的57个样点62属浮游植物与11个环境因子关系进行研究.结果表明,水温、高锰酸盐指数、NO^-₃-N和TN是影响苏州平原河网区浅水湖泊浮游植物群落分布的主要环境因子,在冬季,pH、NH⁺₄-N及TP也是主要的影响因子;浮游植物中硅藻对环境变化具有较强的适应性,绿藻能耐受较高的高锰酸盐指数、氮磷营养盐和TOC浓度,而蓝藻对环境因子的响应有待进一步的研究.     

珠海市磨刀门水道输水水源水库群浮游植物群落特征及其环境驱动因子

磨刀门水道是珠江水系的主要出海口,也是粤港澳大湾区珠海和澳门等多个城市的重要水源地.于2021年丰、枯两季（8月和10月）对珠海市磨刀门水道13个采样点的水质和受其供水的4个饮用水水源水库群21个采样点水质状况和浮游植物开展了调查,并探究了相关驱动机制.4个水库浮游植物群落结构的解析结果显示,浮游植物共有8门73属150种,种类和相对丰度均以蓝藻、绿藻和硅藻为主,其中大镜山水库（DJS）和杨寮水库（YL）蓝藻在丰、枯两季的相对丰度均超过90%,竹仙洞（ZXD）和竹银水库（ZY）的蓝藻、绿藻和硅藻在不同时期分别占优,且分布较均衡.Shanno-Wiener指数（H）、Pielous均匀度指数（J）和Margalef丰富度指数（D）说明竹银水库的浮游植物生物多样性最丰富,指示水体最优,竹仙洞水库次之,大镜山水库是4个水库中浮游植物多样性最少的水库.PCoA分析表明大镜山水库和杨寮水库浮游植物群落结构具有相似性（P>0.05）,且该2个水库和竹仙洞水库、竹银水库均具有显著差异性（P<0.05）.冗余分析（RDA）结果显示,硝酸盐氮（NO₃^-）、总溶解性有机碳（TOC）、总磷（TP）、氯化物（Cl^-）和氨氮（NH₄⁺-N）是影响浮游植物群落分布的主要环境因子.研究结果揭示了4个水库浮游植物群落受磨刀门水道输水带来的营养盐外源影响较大,提示应着重改善磨刀门水道水质,以达到改善和预防水库水体富营养化,确保饮用水水源安全的目的.     

不同水源补给河流浮游植物群落结构特征及其与环境因子的关系

为探究不同水源补给河流浮游植物群落结构的差异,于2019年5~11月对北京市北运河水系和永定河水系7条河流进行逐月采样调查,分析不同水源补给河流浮游植物群落结构特征,并采用相关性分析和冗余分析（RDA）探究浮游植物群落与环境因子之间的关系.结果表明,7条河流共监测到9门127种浮游植物,硅藻、绿藻和蓝藻为优势种群,分别占种类总数的40.94%、34.65%和10.24%.浮游植物密度介于（0.24~169.14）×10⁶ cell·L^-1之间,均值为38.20×10⁶ cell·L^-1,生物量介于0.21~78.50 mg·L^-1之间,均值为16.49 mg·L^-1.浮游植物种类、密度和生物量均表现为：混合水源补给组>完全再生水补给组>无再生水补给组.浮游植物生物多样性指数H''均值介于1.56~2.18之间,均匀度指数J均值介于0.47~0.67之间,H''和J均表现为：无再生水补给组>混合水源补给组>完全再生水补给组.RDA排序结果表明,影响混合水源补给组浮游植物优势种的主要环境因子为DOC、pH、Chla、DO和TP,影响无再生水补给组和完全再生水补给组优势种的主要环境因子为TN、NH₄⁺-N、N/P和ORP.     

溪源宫水源保护区浮游植物群落结构分析研究

文章主要对2011年8月至12月溪源宫水源保护区浮游植物群落结构进行调查分析。溪源宫水体共鉴定出浮游植物6门51属137种,主要都是以绿藻门、硅藻门、蓝藻门为主。通过采用浮游植物生物量以及多样性指数对研究区域水体进行了评价,结果表明溪源宫水源保护区水质状况较好。同时还将溪源宫水源保护区、闽江、山仔水库等不同水源地的浮游植物群落结构进行对比分析,发现不同营养状态下,水体中浮游植物群落结构有显著的不同。     

丹江口水库早春真核浮游植物群落结构特征及其与环境因子的关系

采用高通量测序技术研究了2019年早春（2月）丹江口水库浮游植物群落结构特征及其与环境因子的关系.结果显示：①本次调查共检测到浮游植物6门57属,主要包括绿藻门、硅藻门、金藻门、甲藻门、隐藻门等,其中,绿藻种类（47种）>硅藻（24种）>金藻（17种）,硅藻相对丰度（58.8%）>绿藻（27.2%）>金藻（11.8%）,各采样点浮游植物群落结构总体相似;②浮游植物优势种为硅藻门的冠盘藻（Stephanodiscus suzukii）、变异直链藻（Melosira varians）,绿藻门的葡萄藻（Botryococcus braunii）、索囊藻（Choricystis sp.）,以及金藻类的近囊胞藻一种（Paraphysomonas sp.）;③Shannon-Wiener多样性指数为1.76~2.52,Pielou均匀度为0.28~0.38,依据多样性指数水质评判标准判断水质整体处于β-中污带;水质符合Ⅱ类标准,但总氮（TN）除外,浓度为0.93~1.21 mg·L^-1;④相关性分析表明,香农-威纳指数（H''）与Pielou均匀度指数（J）、Simpson多样性指数显著相关（p<0.01）;冗余分析表明,pH、NH₄⁺-N和NO₂^--N是影响丹江口水库早春季节浮游植物群落结构最主要的环境因子.总体而言,丹江口水库水质较好,但早春季节冠盘藻（Stephanodiscus suzukii）的大量繁殖使丹江口水库发生水华的风险增加,因此,要加强对丹江口水库水质的检测和防范意识.     

“稀释置换”对海河浮游植物群落结构的影响

该研究于2015年夏季蓝藻暴发期对海河干流浮游植物群落结构特征进行调查分析,并以此为基础评价海河干流水域的营养水平及水质污染类型。研究结果表明:4次调查共鉴定浮游植物6门56种(属),其中绿藻门29种(属),蓝藻门13种(属),硅藻门8种(属),甲藻门、裸藻门、隐藻门各2种(属),主要优势种为蓝藻门的微囊藻、巨颤藻、小席藻和色球藻。浮游植物的平均丰度为15 319.4×104个/L,蓝藻门种类对总平均丰度的贡献为95.67%;浮游植物平均生物量为17.87 mg/L,蓝藻门占总平均生物量的53.31%;海河浮游植物丰度和生物量的分布呈现一致性,从上游至下游呈先升高后降低的趋势。依据浮游植物丰度及3种浮游植物群落指数评价结果表明,海河干流水域的水体均为重度富营养化状态,污染状态为中污型。比较分析结果表明:采用不定期、小水体地稀释置换已暴发蓝藻水华的海河干流水体这一应急处置蓝藻水华方式,未对海河浮游植物群落结构、营养状态及污染水平产生本质上的影响。     

不同水期澜沧江梯级水库浮游植物群落结构空间分布特征

建坝造成了河流水环境的差异,会导致浮游植物群落具有明显的空间异质性.为探究梯级水库河流的浮游植物分布,本研究选择澜沧江为研究区域,于2018年3月—2019年5月在上游河道、苗尾、功果桥、小湾、漫湾、糯扎渡、景洪、景洪坝下开展了浮游植物的调查.对比了丰、枯水期浮游植物群落结构、Shannon-Wiener多样性指数、Pielou均匀度指数的变化特征,采用Spearman相关性分析确定丰、枯水期浮游植物密度与环境因子间的关系.重点讨论了浮游植物密度较高的小湾和糯扎渡库区浮游植物的年内变化特征.研究结果表明：澜沧江干流丰、枯水期各库区浮游植物种类均以河流型硅藻为主,绿藻门次之;浮游植物密度分别为0.02×10⁶ ~ 16.74×10⁶ cells?L^-1和0.26×10⁶ ~ 9.41×10⁶ cells?L^-1;丰水期藻密度、生物量、浮游植物多样性、均匀度指数均高于枯水期;小湾和糯扎渡的浮游植物密度及生物量均高于其他库区,全年平均值分别为9.35×10⁶ cells?L^-1和2.19×10⁶ cells?L^-1;两库的浮游植物群落具有明显差异,浮游植物密度分别在2019年5月和4月达到最高,相关性分析表明氮素是影响浮游植物群落结构变化的关键因子.本研究可为梯级水库河流的水生态环境保护提供一定的支撑和参考.     

不同黑臭程度下城市河道浮游植物群落结构、多样性和功能群

浮游植物群落特征、多样性和功能群分析可以反映水体环境质量状态.为探究城市河道黑臭对浮游植物群落的影响,2020年11月至2021年3月,以四川盆地内16条城市河道,38个采样点水环境质量调查数据为基础,基于改进的模糊综合评价模型法和k-均值主颜色提取法评价城市河道黑臭程度,将河道划分为不黑不臭型、只黑不臭型、只臭不黑型和又黑又臭型这4种河道类型,在此基础上对不同黑臭类型河道的浮游植物群落结构、多样性和功能群进行分析.结果表明,城市河道从不黑不臭型至又黑又臭型,浮游植物丰度从1.329×10⁵ cells ·L^-1升至6.627×10⁵ cells ·L^-1,组成由蓝藻-绿藻-硅藻型变化为蓝藻型;浮游植物生物量从64.056 μg ·L^-1升至120.465 μg ·L^-1,组成由适应营养盐环境的绿藻-硅藻型转变为适宜有机物环境的甲藻-硅藻-裸藻型;Shannon-Weaver多样性指数从2.45下降到1.98,Simpson指数从0.84下降到0.73.研究区域浮游植物共29个功能群,随着水质黑臭化,生长策略由S、R、C、CR和CS型组成,减少为以R型为主.综上,浮游植物指标能较好地反映河道黑臭状态,在城市河道黑臭管理中,浮游植物监测是具有前景的手段和方法.     

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.     

Impact of atrazine and nitrogen fertilizers on the sorption of chlorotoluron in soil and model sorbents

Sorption of chlorotoluron in ammonium sulfate, urea and atrazine multi-solutes system was investigated by batch experiments. The results showed application of nitrogen fertilizers to the soil could affect the behavior of chlorotoluron. At the same concentration of N, sorption of chlorotoluron decreased as the concentration of atrazine increased on the day 0 and 6 in soil, respectively. The sorption of chlorotoluron increased from 0 to 6 d when soils were preincubated with deionized water, ammonium sulfate and urea solution for 6 d. That indicated incubation time was one of the most important factors for the sorption of chlorotoluron in nitrogen fertilizers treatments. The individual sorption isotherms of chlorotoluron in rubbery polymer and silica were strictly linear in single solute system, but there were competition sorption between pesticides or between pesticides and nitrogen fertilizers. That indicated the sorption taken place by concurrent solid-phase dissolution mechanism and sorption on the interface of water-organic matter or water-mineral matter.     

Degradation of metabolites accumulated of benzo[a]pyrene by coupling Penicillium Chrysogenum with KMnO4

Several main metabolites of benzo[a]pyrene （BaP） formed by Penicillium chrysogenum, Benzo[a]pyrene-1,6-quinone （BP 1,6- quinone）, trans-7,8-dihydroxy-7,8-dihydrobenzo[a]pyrene （BP 7,8-diol）, 3-hydroxybenzo[a]pyrene （3-OHBP）, were identified by high-performance liquid chromatography （HPLC）. The three metabolites were liable to be accumulated and were hardly further metabolized because of their toxicity to microorganisms. However, their further degradation was essential for the complete degradation of BaP. To enhance their degradation, two methods, degradation by coupling Penicillium chrysogenum with KMnO4 and degradation only by Penicillium chrysogenum, were compared; Meanwhile, the parameters of degradation in the superior method were optimized. The results showed that （1） the method of coupling Penicillium chrysogenum with KMnO4 was better and was the first method to be used in the degradation of BaP and its metabolites; （2） the metabolite, BP 1,6-quinone was the most liable to be accumulated in pure cultures; （3） the effect of degradation was the best when the concentration of KMnO4 in the cultures was 0.01% （w/v）, concentration of the three compounds was 5 mg/L and pH was 6.2. Based on the experimental results, a novel concept with regard to the bioremediation of BaP-contaminated environment was discussed, considering the influence on environmental toxicity of the accumulated metabolites.     

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.     

Effects of two sludge application on fractionation and phytotoxicity of zinc and copper in the soil

The potential harm of heavy metals is a primary concern in application of sludge to the agricultural land. A pot experiment was conducted to evaluate the effect of two sludges on fractionation of Zn and Cu in soil and their phytotoxicity to pakchoi. The loamy soil was mixed with 0%, 20%, 40%, 60% and 80% (by weight) of digested sewage sludge (SS) and composted sludge (SC). The additions of both sludges caused a significant raise in all fractions, resulting in that exchangeable (EXCH) and organic bound (OM) became predominance of Zn and organic bound Cu occupied the largest portion. There was more available amount of Zn and Cu in SS treatments than SC treatments. During the pot experiment, the concentration of Zn in EXCH, carbonate (CAR) and OM and Cu in EXCH and OM fractions decreased in all treatments, so their bioavailability reduced. Germination rate and plant biomass decreased when the addition rate was high and the best yield appeared in 20% mixtures at the harvest of pakchoi. The two sludges increased tissue contents of Zn and Cu especially in the SS treatments. Zn in pakchoi was not only in relationship to ΔEXCH and ΔCAR forms but also in ΔOM forms in the sludge-soil mixtures. Tissue content of Cu in pakchoi grown on SC-soils could not be predicted by ΔEXCH. These correlation rates between Zn and Cu accumulation in pakchoi and variation of different fractions increased with time, which might indicate that sludges represented stronger impacts on the plant in long-term land application.     

Intraspecific differences in effects of co-contamination of cadmium and

A hydroponic experiment was carried out to study intraspecific differences in the effects of different concentrations of cadmium (Cd)(0-10 mg/L) and arsenate (As(V)) (0-8 mg/L) on the growth parameters and accumulation of Cd and As in six wheat varieties Jing-9428, Duokang-1, Jingdong-11, Jing-411, Jingdong-8 and Zhongmai-8. The endpoints of wheat seedlings, including seed germination,biomass, root length and shoot height, decreased with increasing the Cd and As concentrations. Significant differences in seed germination, biomass, root length, shoot height and the accumulation of Cd and As were observed between the treatments and among the varieties (p ＜ 0.05). The lethal dosage 50% were about 20, 80, 60, 60, 80 and 20 mg As/L for Jing-9428, Duokang-1, Jingdong-11,Jing-411, Jingdong-8 and Zhongmai-8, respectively, and the corresponding values for Cd were about 30, 80, 20, 40, 60 and 10 mg Cd/L, respectively. Among the six varieties, Duokang-1 was found to be the most resistant to Cd and As toxicity, and Zhongmai-8 was the most sensitive to Cd and As co-contamination. The resistance of the six varieties was found dependant on the seedling uptake of Cd and As. Duokang-1 was the most suitable for cultivation in Cd and As co-contaminated soils.     

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

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Isolation and preliminary characterization of a 3-chlorobenzoate degrading bacteria

A study was conducted to compare the diversity of 2-, 3-, and 4-chlorobenzoate degraders in two pristine soils and one contaminated sewage sludge. These samples contained strikingly different populations of mono-chlorobenzoate degraders. Although fewer cultures were isolated in the uncontaminated soils than contaminated one, the ability of microbial populations to mineralize chlorobenzoate was widespread. The 3- and 4-chlorobenzoate degraders were more diverse than the 2-chlorobenzoate degraders. One of the strains isolated from the sewage sludge was obtained. Based on its phenotype, chemotaxonomic properties and 16S rRNA gene, the organism S-7 was classified as Rhodococcus erythropolis. The strain can grow at temperature from 4 to 37℃. It can utilize several （halo）aromatic compounds. Moreover, strain S-7 can grow and use 3-chlorobenzoate as sole carbon source in a temperatures range of 10-30℃ with stoichiometric release of chloride ions. The psychrotolerant ability was significant for bioremediation in low temperature regions. Catechol and chlorocatechol 1,2-dioxygenase activities were present in cell free extracts of the strain, but no （chloro）catechol 2,3- dioxygenase activities was detected. Spectral conversion assays with extracts from R. erythropolis S-7 showed accumulation of a compound with a similar UV spectrum as chloro-cis,cis-muconate from 3-chlorobenzoate. On the basis of these results, we proposed that S-7 degraded 3-chlorobenzoate through the modified ortho-cleave pathway.     

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.