快速城市化区域不同用地类型土壤重金属含量分布特征及生态风险

以上海市闵行区典型快速城市化区域为例,基于36个地块595个点位土壤样品数据,分析5种不同土地利用类型中8项土壤重金属的含量分布特征,通过内梅罗综合指数法和潜在生态风险指数法进行生态风险评价.结果表明,重金属锌和镉含量的变异系数较高,受人为活动影响特征明显.涉重工业用地、非涉重工业用地的重金属赋存相对较高,住宅用地和耕地重金属含量总体不高但具有其特异性组成特征,公共管理与公共服务用地相对最低.重金属锌和镉的内梅罗综合污染指数较高,分别处于重度和中度污染水平,其余重金属均为警戒或轻度污染水平.不同土地利用类型的土壤重金属潜在生态风险水平为：涉重工业用地 > 非涉重工业用地≈住宅用地 > 耕地≈公共管理与公共服务用地,工业用地由于行业类别多、历史生产复杂和管理水平差异大等原因,具有较大的土壤重金属污染风险,住宅用地和耕地等其他用地类型也呈现出一定的重金属累积趋势.不同土地利用的土壤重金属污染源头防控和地块再开发利用的安全性及风险管控,是快速城市化区域土壤污染防治的重点和难点.     

辽东湾北部河口区土壤重金属污染源识别及健康风险评价

选取我国北方典型河口区—辽东湾北部区为研究对象,共采集129个表层土样,测定了Cu、Cr、Cd、Ni、Zn和Pb等土壤重金属含量,利用地统计分析、地累积指数（I_geo）、内梅罗指数、潜在生态风险指数（RI）、多元统计分析及健康风险模型对研究区土壤重金属的空间分布特征、污染来源及健康风险进行系统分析,并对区域人居环境改善提出对策建议.结果表明：①研究区土壤中Cu、Cr、Cd、Ni、Zn和Pb的平均含量分别为17.87、148.97、1.31、40.91、102.86和12.42 mg·kg^-1,除Cu和Pb以外都超过了辽宁省土壤背景值;②6种重金属污染程度排序为Cd > Cr > Zn > Ni > Cu > Pb,其中Cd元素污染最严重;土壤重金属综合生态风险指数RI为325.689,处于重度生态风险水平,Cd是主要的生态风险因子;③多元统计分析表明,重金属Cu、Zn和Pb主要受自然因素影响,Cr和Ni主要源于生活及工业废水排放,Cd以磷肥的大量使用、石油化工生产及工业活动作为主要的人为来源;④健康风险评价结果表明,皮肤接触暴露途径中儿童的非致癌风险大于成人,呼吸暴露途径中成人的致癌风险大于儿童,元素Cr的总致癌风险R_all<10^-6,不存在致癌风险,Cd的总致癌风险10^-4 < R_all < 10^-6,存在可接受致癌风险;⑤河口海岸区对我国海湾及沿海区域经济发展意义重大,土壤重金属污染和人居健康问题已经不容忽视,希冀本研究可为当地政府及同类区域提供科学借鉴.     

青藏高原重要交通国道路侧土壤重金属分布特征及生态风险评价

为了阐明交通对青藏高原敏感脆弱生态系统和主要生态安全屏障功能的影响,在G214、 G213、 G345、 G109、 G316和G317等国道部分路段,采集路边0~25 m范围内土壤样品,分析6种土壤重金属含量及分布特征,运用单因子污染指数法（P_i）、内梅罗综合指数法（P_N）及潜在生态风险指数法（RI）对路侧土壤重金属的污染程度及潜在生态风险进行综合评价.结果表明,青藏高原重要交通国道路侧土壤重金属ω（As）、 ω（Cd）、 ω（Hg）、 ω（Ni）、 ω（Pb）和ω（Zn）分别介于5.65~176.00、 0.04~0.27、 0.01~0.14、 9.52~113.00、 9.16~54.50和24.70~109.00 mg·kg^-1,呈高度变异,部分采样路段存在As、 Cd和Hg元素高于当地土壤背景值.路侧土壤重金属单因子污染指数大小为：P_i （As） > P_i （Hg） > P_i（Cd） > P_i （Pb） > P_i （Ni） > P_i （Zn）,内梅罗综合污染指数在0.41~9.20,平均值为1.53,属于清洁或轻度污染,局部处于中度或重度污染.研究路段综合潜在生态风险指数平均值为106.2,土壤总体处于无污染和轻度污染,仅有两个路段的土壤重金属富集达到中等及强度生态危害,其G213a土壤综合潜在风险指数显示为中度至重度生态危害,主要受到Hg、 As和Cd的影响,G317土壤综合潜在风险指数显示为轻度至中度生态危害,主要受到Hg和Cd的影响.青藏高原路侧土壤重金属含量与路侧距离及土壤深度没有显著相关性,与年均气温呈显著正相关（P < 0.05）.青藏高原道路建设人为活动剧烈、交通流量较大的区域有土壤重金属富集趋势.     

白洋淀及周边土壤重金属的分布特征及生态风险评估

为了解白洋淀土壤重金属污染现状和潜在生态风险,采集白洋淀区域表层土壤样本55个并检测锰（Mn）、铬（Cr）、铜（Cu）、锌（Zn）、砷（As）、镉（Cd）、铅（Pb）和镍（Ni）等8种重金属的含量.采用地统计学方法（莫兰指数和半方差函数）分析其空间变异结构和分布格局,运用地累积指数（I_geo）和潜在生态风险指数（E_rⁱ和RI）评估了重金属污染的程度及其风险.结果表明,研究区土壤重金属ω（Mn）、ω（Cr）、ω（Cu）、ω（Zn）、ω（As）、ω（Cd）、ω（Pb）和ω（Ni）平均值分别为467.75、43.59、28.57、89.04、12.32、0.18、19.26和30.56 mg ·kg^-1,均低于农用地土壤污染风险筛选值,但Cu、Zn和Cd明显高于背景值,其中,Cu （48.65%）和Cd （37.52%）为高度变异元素.莫兰指数显示Mn、Cu、Cd和Pb空间自相关不显著,半方差函数模型拟合显示Cd和Pb的块金系数均为100%,说明其空间变异由随机变异主导,受人为因素影响较大.重金属高值区主要分布在白洋淀的西南部地区,并且元素之间均有显著的相关性,表现为复合污染.重金属污染程度I_geo从高到低依次为：Cd>Cu>Zn>Ni>As>Pb>Mn>Cr,其中,Cd污染最为普遍,67.27%的样本为轻度污染.风险评估（E_rⁱ）显示,Cd的E_rⁱ平均值为58.81,属于中等程度生态风险;其他重金属均为轻微生态风险.研究区土壤重金属污染RI为轻微生态风险（87.81）,其中,Cd对RI的贡献率最高（66.39%）.因此,未来需要加强对白洋淀西南部重点区域重金属Cd污染的监测和治理.     

石家庄市栾城区农田土壤重金属分布特征及作物风险评价

为探讨栾城区内农田土壤重金属的分布特征,对表层土壤As、Cd、Cr、Cu、Hg、Ni、Pb和Zn这8种重金属污染特征、空间分布和污染风险进行分析,并使用PMF模型进行污染源解析,探讨栾城区土壤管控方案.进一步检测作物中重金属含量,利用概率风险评价方法评价研究区农产品的非致癌健康风险,为栾城区内农田土壤重金属污染治理与防控提供理论基础.结果表明,表层土壤ω（Cd）、ω（Cr）、ω（Cu）、ω（Pb）和ω（Zn）分别为0.06~1.08、22.14~473.47、12.83~150.74、10.75~577.72和62.23~652.78 mg·kg^-1,点位超标率分别为1.83%、1.22%、0.61%、0.61%和1.22%.此外,部分区域土壤中的重金属有向作物中转移并积累的现象,小麦籽粒Cd和Pb含量超标率分别为2.13%和5.32%,玉米籽粒Cd含量超标率为1.20%.健康风险评价结果表明,栾城区玉米的复合非致癌健康风险（TTHQ）小于1,对人体没有明显的负面影响,食用研究区小麦的复合非致癌风险（TTHQ>1）,对人体产生负面影响的可能性较大.土壤中重金属的空间分布受工业区涉污企业分布的影响,8种重金属含量较高的区域均主要分布在工业企业较集中的中部、西部和南部.总体而言,研究区大部分表层耕地土壤未受到明显的重金属污染,存在中等强度（2级）的生态危害.Cd为无-中度污染（1级）,Cd和Hg存在中等强度潜在生态风险（2级）,其余重金属均为无污染,低潜在生态风险（1级）.根据PMF污染源解析结果和实地调查推测,土壤重金属主要来自土壤母质（52.05%）,历史污灌和工业生产的人为污染源（32.98%）和大气沉降（14.97%）.综上所述,研究区北部和东部土壤重金属含量较低,应划分为优先保护类,研究区西部、中部和南部部分点位重金属含量超标,其来源主要为化工、涂料、机械装备等企业,应划分为安全利用类,严控污染物的输入,采用农艺调控等措施,减少重金属向农作物的转移,降低食品安全健康风险.本研究将有助于栾城区土壤的分级治理和污染管控.     

基于蒙特卡罗模拟的煤矸山周边农用地土壤重金属健康风险评估

以重庆市煤矸山周边农用地土壤为研究对象,运用内梅罗指数、地累积指数和潜在生态风险指数分析土壤重金属污染水平,并采用蒙特卡罗模拟的健康风险模型,探析研究区土壤重金属对人体的健康风险.结果表明,研究区土壤Cd、Hg、As、Pb、Cr、Cu、Ni和Zn含量均值超重庆市土壤背景值,地累积指数（I_geo）表现为：Cd>Hg>Cu>As>Ni>Zn>Cr>Pb;内梅罗指数表明土壤以轻污染（1<P_N≤2）为主,各重金属污染指数（P_i）表现为：Cd>Cu>Ni>Cr>Zn>As>Pb>Hg;潜在生态风险指数表明土壤以中等生态风险（150≤RI<300）为主,各重金属生态风险指数（E_rⁱ）表现为：Cd>Hg>As>Cu>Ni>Pb>Cr>Zn.土壤健康风险表明,儿童和成人非致癌健康风险可忽略,但存在可耐受致癌健康风险,综合致癌风险指数（TCR）均值分别为1.04E-5和3.94E-6,主要致癌因子为As和Cd.敏感性分析表明非致癌健康风险土壤颗粒摄入速率（R_ingest）敏感性最高,其次是As含量,致癌健康风险土壤颗粒摄入速率As含量敏感性最高,其次是土壤颗粒摄入速率（R_ingest）.整体上儿童非致癌和致癌健康风险高于成人.     

三峡库区(重庆段)菜地土壤重金属污染特征、潜在生态风险评估及源解析

为探究三峡库区菜地土壤重金属的污染特征、潜在生态风险和污染物的来源,于2021年10月采集了库区（重庆段）14个蔬菜种植区（县）菜地的表层土壤样品,分析了样本中7种重金属元素（As、Cd、Cr、Cu、Ni、Pb和Zn）的含量,分别利用单因子指数法、内梅罗综合污染指数法和潜在生态风险评价法对土壤重金属的富集状况和潜在风险进行了评估,并分析了蔬菜种植年限和栽培方式（露天和大棚）对土壤重金属累积的影响.结果表明,库区菜地土壤中重金属的含量高于重庆市三峡库区土壤背景值,但均低于《农用地土壤污染风险管控标准（试行）》（GB 15618-2018）规定的土壤污染风险管制值;单因子污染评价结果表明,区域土壤Pb、Zn、Cu和Cd处于轻微污染水平;内梅罗综合污染指数法表明,研究区处于轻度污染水平,主要污染因子为Cd和Ni,有91.4%的土壤样品存在不同程度的污染（P_N>1）,其中9.19%的样品处于重度污染;潜在生态风险评估结果指出,研究区以轻度生态风险为主,Cd中度生态风险的土壤样本数占比为9.77%,存在一定的生态风险.聚类分析结果显示Cd-Cu-Pb-Zn和As-Cr-Ni分别具有相同的污染源.菜地土壤中重金属含量随着种植年限的增加均呈上升趋势;总体上大棚土壤中重金属含量均高于露天菜地土壤.     

乌梁素海表层沉积物中营养盐和重金属分布特征以及风险评价

为了解乌梁素海表层沉积物中营养盐和重金属污染情况,于2021年7月对乌梁素海16个采样点位表层沉积物中总氮、总磷和9种重金属的含量进行了测定分析.结果表明,表层沉积物中ω（TN）和ω（TP）均值为7.91 g·kg^-1和1.89 g·kg^-1,变异系数分别达到了27.96%和43.51%,具有一定的空间差异;营养盐污染指数表明,乌梁素海表层沉积物中TN和TP均处于严重污染程度.表层沉积物中Cr、Ni、Cu、Zn、Cd和Hg等重金属均已超过了背景值,其中Cd和Hg超标最严重,重金属地累积指数（I_geo）也显示Cd和Hg生态风险严重.乌梁素海表层沉积物中重金属潜在生态风险指数值RI值介于337.82~681.88之间,均值为504.39,处于强的潜在生态风险,其中Cd和Hg两种重金属对RI贡献最高,贡献率分别达到了47.83%和43.99%.     

江西省主要城市土壤重金属污染及风险评价

该研究分析了江西省8个主要城市（南昌、九江、上饶、景德镇、抚州、宜春、吉安、赣州）中农业用地、生活用地和工业用地的150个表层土壤样品中重金属的污染特征。采用主成分分析（PCA）和正定矩阵因子模型（PMF）分析土壤重金属的潜在污染来源,并运用综合污染指数法、地质累积指数法、潜在生态风险指数法和人体健康风险评估对土壤重金属暴露的生态风险和健康风险进行评价。结果表明：南昌市土壤中镉中值含量（Cd,0.74 mg/kg）是江西省背景值的6.7倍,九江市土壤中汞中值含量（Hg,2.4 mg/kg）是其背景值的30倍。PCA和PMF分析表明,农业用地土壤重金属的主要来源为施肥（磷肥、有机肥）等农业活动;南昌市和抚州市的生活用地和工业用地土壤重金属的主要来源是城市生活垃圾和交通运输等人为活动;而赣州市、九江市、景德镇市和上饶市的生活用地和工业用地土壤重金属主要来源是矿业开采、金属冶炼、煤炭燃烧等工业活动。综合各生态风险指数评价的结果,江西省主要城市表层土壤重金属的生态风险较低,属于轻微污染,其中以Cd和Hg为主要风险元素。对于人体健康风险,生活用地土壤重金属经口摄入的总危害商（∑HQ）为1.56,...     

长江中游典型湖泊沉积物重金属分布特征、生态风险评估及溯源

集中采集洞庭湖、洪湖和赤湖表层沉积物样品并检测其中10种重金属含量,使用地理信息系统表征空间分布,利用地累积污染指数法（I_geo）、富集因子法（EF）和潜在生态风险指数法（RI）协同评估重金属积累的潜在风险,并利用相关性分析（Pearson）和主成分分析（PCA）溯源.结果表明,Cd元素的污染状况和潜在生态风险最为严重,东洞庭湖、洪湖和赤湖中ω（Cd）的平均值分别为2.85、1.59和3.57 mg·kg^-1,分别是对应省份土壤背景值的25.87、11.36和37.58倍,均超出风险筛选值（0.6 mg·kg^-1）,其中赤湖超出风险管制值（3.0 mg·kg^-1）.除Cd外,洪湖中的As值得关注,赤湖中的Cu、As、Zn和Pb都不容忽视.三湖的潜在生态风险排序为：赤湖（RI=1 127）>东洞庭湖（RI=831）>洪湖（RI=421）.重金属来源主要是工矿业冶采、农业生产和水产养殖等,部分重金属（Mn和Cu）为自然源.研究对长江中游典型湖泊沉积物重金属防控具有重要意义.     

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.     

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.     

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.     

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.     

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.     

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.     

Alterations of organ histopathology and metallolhionein mRNA expression in silver barb, Puntius gonionotus during subchronic cadmium exposure

Common silver barb,Puntius gonionotus,exposed to the nominal concentration of 0.06 mg/L Cd for 60 d,were assessed for histopathological alterations(gills,liver and kidney),metal accumulation,and metallothionein(MT)mRNA expression.Fish exhibited pathological symptoms such as hypertrophy and hyperplasia of primary and secondary gill lamellae,vacuolization in hepatocytes,and prominent tubular and glomerular damage in the kidney.In addition,kidney accumulated the highest content of cadmium,more than gills and liver.Expression of MT mRNA was increased in both liver and kidney of treated fish.Hepatic MT levels remained high after fish were removed to Cd-free water.In contrast,MT expression in kidney was peaked after 28 d of treatment and drastically dropped when fish were removed to Cd-free water.The high concentrations of Cd in hepatic tissues indicated an accumulation site or permanent damage on this tissue.