贵州省某市土壤中有机氯残留及风险评价

运用气相色谱法和生态分析评价法对贵州某市三县区土壤样品中有机氯残留及可能存在的生态风险进行分析。结果显示:该地区土壤中有机氯农药残留以六六六和滴滴涕为主:六六六残留量为ND~4.907μg kg-1,均值为0.303μg kg-1;滴滴涕残留量为0.115~29.900μg kg-1,均值为3.360μg kg-1,滴滴涕均值较六六六高。土壤中有机氯浓度及代谢物表明,滴滴涕和六六六主要来自历史性输入,六氯苯来自大气沉降输入。利用RBCA健康风险评价模型对土壤中有机氯污染物进行评价,结果表明该地区土壤中有机氯对人体健康风险较低。     

有机氯农药在农业环境中残留现状分析

经对不同耕作土壤和农作物中有机氯 (六六六、滴滴涕 )残留调查、监测 ,阐述有机氯农药在停止使用十多年后 ,其有害物在土壤中的残留状况 ,并针对农业生产提出相应的防治途径。     

唐山市土壤中有机氯农药的初步研究

采用加速溶剂萃取技术——气相色谱法,初步研究了唐山市区不同类型土壤中有机氯农药的成分及其含量,并对有机氯农药进行了溯源分析。结果表明所测的4种类型的土壤中六六六(HCHs)和滴滴涕(DDTs)均有检出,HCHs的平均含量为15.015ng·g-1,DDTs的平均值含量为66.4ng·g-1,均大大高于20世纪70年代我国有机氯农药使用量最大的棉田土壤中的残留量11.68ng·g-1和0.80ng·g-1。土壤中有机氯农药的高残留应该与唐山地震后喷洒大量有机氯农药有密切关系。     

基于多元地统计和GIS的珠江三角洲典型区域土壤有机氯农药残留状况及其空间分布研究——以惠州市为例

选取位于珠江三角洲的惠州市为研究区域,对该市土壤进行了系统采样分析,测定了42个表层土壤样品中的17种有机氯农药的含量。利用多元地统计和GIS相结合的方法,研究了17种有机氯农药的残留状况及空间分布情况。结果表明,17种有机氯农药在42个土壤样品中均有不同程度的检出,其中p,p′-DDE检出率为100%,3种有机氯农药检出率在90%以上,6种有机氯农药的检出率在80%以上。其中六六六和滴滴涕残留较普遍,但并未达到污染水平。分析显示,近期可能仍有新的六六六输入土壤环境,而滴滴涕则主要来自过去施用农药的残留。与国内其他地区比较,惠州市土壤HCH和DDT含量处于较低水平。主成分分析显示上述17种有机氯农药可以由5个主成分反映,分别对应于工业HCH的使用、自然因素、林丹的使用以及七氯和艾氏剂等农药的使用。采用克里格插值法对有机氯农药在研究区的空间分布进行了研究,结果表明不同有机氯农药在研究区分布存在很大差异。     

珠三角典型区域土壤有机氯农药（OCPs）多元统计分析——以佛山市顺德区为例

选取位于珠江三角洲的佛山市顺德区作为研究对象,分析了26个代表性土壤样品中的17种有机氯农药(OCPs)的含量,并对其来源进行分析。结果显示,17种OCPs在26个土壤样品中均有不同程度的检出,个别有机氯农药的检出率达到100%。六六六异构体中β-HCH的残留量最高,可能与β-HCH的结构有关。另外,可能有新的γ-HCH进入土壤环境。六六六和滴滴涕残留较普遍,但残留量均未达到污染水平。根据分析,土壤中滴滴涕农药主要是过去施用农药的残留,近期没有新的滴滴涕农药进入土壤环境。通过主成分分析可以从除七氯环氧化物、硫丹?、p,p’-DDD和p,p’-DDT之外的13种有机氯农药中提取出两个主成分,总方差解释量达到了92.28%。第一主成分主要包括了α-HCH、七氯、艾氏剂、p,p’-DDE、δ-HCH、硫丹Ⅱ等6种农药,这6种农药之间有着明显的相关性;第二主成分主要包括狄氏剂。     

上海农田土壤中六六六和滴滴涕污染分布状况研究

土壤环境中的污染物积累及其在食物链中的迁移、富集、转化是影响食品安全的重大科学问题。有机氯农药,主要包括六六六和滴滴涕,因不易分解且具有一定挥发性和强脂溶性,能通过食物链传递污染整个生态环境,进而危害人类身体健康,其污染和治理的研究受到国内外广泛关注[1~6]。前人分别从不同的角度对土壤六六六和滴滴涕进行了研究,包括其迁移转化[2]、生物有效性[3]、残留特征与空间分布[4,5]及其对人类健康影响[6]等。国内外研究表明,无论是发达的工业国家还是农业国家均频繁地从土壤中检出六六六和滴滴涕的残留物[7];我国局部地区的土壤六六六和滴滴涕的残留量亦仍然较高[5,8]。因此六六六和滴滴涕残留仍是土壤     

基于三次样条插值法的土壤中有机氯污染研究

根据2003年、2007年以及2009年的北京官厅水库地区表层土壤中有机氯农药(OCPs)残留实验数据,应用三次样条插值法对缺失年份的数据进行了补充,并预测了2010年的数据。在此基础上,分析了各采样点OCPs浓度时间变化规律及原因,探讨了影响有机氯农药降解的因素,并且参照国家土壤环境质量评价标准,对区域表层土壤中有机氯的污染现状进行了评价。结果显示:部分样点OCPs含量随着时间的变化存在反弹,判断存在OCPs的外源性输入;土壤质地对OCPs降解速率有很大程度上的影响,立地植被的影响不显著;对比国家土壤质量一级标准来看,2003年至2009年均未检出总六六六(∑HCH)超标样点,采样点的总滴滴涕(∑DDT)浓度至2009年也均下降至国家土壤环境质量标准一级限值内;预计到2010年,采样点总六六六浓度基本保持恒定,总滴滴涕仍维持良好的降解趋势。     

油料作物和粮食作物种子中有机氯农药残留分析

为了调查作物种子中有机氯残留的现状和种子脂质含量与种子中有机氯残留的关系,本文通过GC-ECD对某农产品基地的油料作物花生、大豆、芝麻和粮食作物水稻、小麦、玉米种子中有机氯农药残留进行了分析.结果表明,对照WHO/FAO标准,6种作物种子中的滴滴涕(DDT)和六六六(HCH)残留均不超标;总DDT的残留范围是3.8～10.3 ng/g,残留顺序是花生>芝麻>大豆>玉米>小麦>水稻;总HCH的残留范围是4.3～10.7 ng/g,残留顺序是花生>玉米>芝麻>大豆>小麦>水稻.3种油料作物种子中的总DDT残留浓度显著高于3种粮食作物种子中的残留浓度,种子中的总DDT残留浓度与种子脂质含量的对数显著正相关.     

有机氯类农药在包气带及地下水中长期残留研究

采用现场采样及室内测试分析方法对吉林省西部松原地区农田－水田、旱田种植类型下的包气带及地下水中有机氯类农药的长期残留进行了研究。结果表明，在研究区包气带土壤的各个取样层位都检测到了有机氯类农药，均为六六六、滴滴涕，在地下水中检测到了β体六六六。同时解释了不同类型农田包带中六六六异构体含量差异的原因。     

海南省瓜菜田土壤中有机氯农药残留及生态风险分析

采用气相色谱法检测了海南瓜菜田的33个表层土壤样品中18种有机氯(OCPs)农药残留,并对其进行污染来源分析和初步生态风险评价。结果表明:(1)土壤中的OCPs检出率为90.9%,最高残留量为17.37 ng·g-1,平均值为2.30 ng·g-1;(2)18种OCPs均有检出,六六六(HCHs)、滴滴涕(DDTs)、硫丹类农药的检出率较高,分别为63.6%、57.6%、54.5%;(3)DDTs是主要残留物质,占总OCPs残留量的54.6%,18.2%的土样可能有DDTs新的输入,土壤中HCHs主要来源于过去使用的林丹;(4)与国内其他地区土壤和国家《土壤环境质量标准》(GB 15618—1995)一级标准相比,海南省瓜菜田土壤DDTs和HCHs残留量处于较低水平,生态风险也较低。     

Effect of insecticides on the availability of nutrients,nitrogen fixation,and phosphate solubility in the rhizosphere soil of rice

A field experiment was conducted to investigate the effects of 1,2,3,4,5,6-hexachlorocyclohexane (BHC), phorate, carbofuran, and fenvalerate, at their recommended doses, on some chemical and microbiological properties of the rhizosphere soil in relation to rice yields. In general, the insecticides had a beneficial effect on rhizosphere soil properties. Carbofuran strongly stimulated the mineralization of organic C. BHC and phorate led to the retention of less total N in the soil. BHC released more NH _inf4 ^sup+ -N than the other insecticides. Phorate, however, liberated the most NO _inf3 ^sup- -N. Phorate and fenvalerate released more available P than BHC and carbofuran did. All the insecticides stimulated the proliferation of aerobic non-symbiotic N₂-fixing and phosphate-solubilizing microorganisms, resulting in an overall increase in rice yield. BHC had the greatest effect on rice yields, followed by phorate.     

农药在土壤中的分布——DDT、BHC量与土粒粒径、有机质量之间的关系

本研究采用干筛法和重力干沉降法对5种表土进行土粒粒径分离,研究在北京地区的风沙季节,地表土的DDT、BHC量与土粒粒径、有机质量之间的关系。结果表明,土壤残留DDT、BHC农药主要分布在土粒粒径为<0.25mm组分中,其中容易被气流浮动的<0.05mm粒径组分的DDT和BHC量,分别占原来表土量的41-89%和30-81%。在一定粒径范围,粒径越小,DDT、BHC含量越高,且与有机质含量之间呈极显著正相关(P<0.01)。同时,土粒中DDT、BHC及其某些代谢产物和异构体的比例却随土粒粒径的不同而变化。     

DDT and HCH Residues in Basmati Rice (Oryza sativa) Cultivated in Dehradun (India)

Organochlorine pesticides were used earlier for agricultureproduction. Their residues may still be present in soil and mayaccumulate in food crops, posing potential health problems to consumers. DDT, HCH, their isomers and metabolites were analyzedin samples of soil and rice plants collected from ten differentvillages of a well-known Basmati rice growing area in Dehradun.Residues of both pesticides were found in all samples ofsoil and different parts of rice plants except for a few grainsamples. Maximum residue was observed in husk and minimum ingrains. The average concentration of DDT in soil ranged from0.013 to 0.238 ppm. p,p′-DDE was the major metabolite (>63%). Theaverage concentration of DDT in rice grain varied from 0.002 to 0.040 ppm. o,p′-DDT was the main isomer (>93%). Theaverage concentration of HCH in soil ranged from 0.122 to 0.638 ppm. β-HCH was the predominant (43%) isomerfollowed by α-HCH (21%). The average HCH concentrationin rice grain ranged between 0.013 and 0.113 ppm. All four isomers were present in grains. The levels of DDT and CHCin grains were similar in magnitude as those from differentIndian states, but well below the maximum residue limit of 0.1 ppm for DDT and 0.05 ppm for HCH prescribed by the Government ofIndia and WHO/FAO. As such, the pesticide residue levels in thisexport commodity are not of hazardous nature.     

Community structure of microeukaryotes in a rice rhizosphere revealed by DNA-based PCR-DGGE

Rice roots provide a specific habitat for microorganisms in the rhizosphere of a submerged field through supply of oxygen and organic matter. Many studies have focused on the microbial community in the rice rhizosphere, but less is still known about the microeukaryotic community structure of rice rhizosphere. This study explored the microeukaryotic community structure of a rice rhizosphere through denaturing gradient gel electrophoresis (DGGE) targeting 18S rRNA gene. The rice roots and the rhizosphere soil samples, which were collected from a field under rice-wheat rotation system, were separately analyzed. To characterize the rice rhizosphere-specific community, the bulk soil of rice field and the wheat rhizosphere samples were also examined. DGGE fingerprints showed that the microeukaryotic community of rice roots were distinct from the community of the bulk soil and showed a temporal shift with the growth stage. The rhizosphere soil community was distinct from the root and bulk soil communities, but this could be explained by that the root and bulk soil communities were shared in the rhizosphere. The rice rhizosphere community was also distinct from those in the wheat rhizosphere. Microeukaryotes that characterized the rice rhizosphere (roots and the rhizosphere soil) community could be affiliated to Polymyxa, flagellates, and oomycetes, which suggested that microeukaryotes with various ecological roles, e.g., parasites, bacterial grazers, and decomposers, inhabit the rice rhizosphere. The results showed that the rice root and its growth stages are key factors shaping the microeukaryotic community structure in the rhizosphere.     

水稻对土壤中DDT及其系列降解物的吸收

在温室条件下,盆栽种植水稻(Oryza sativa,淹水土壤),设老化态DDT残留和新施入DDT两种处理,生长期126 d。研究结果显示:老化残留DDT在土壤中降解十分缓慢,而新施入DDT在土壤中降解相当迅速,GC/MS鉴定结果表明,降解物除DDD外,还有DDMS和DDMU。尽管土壤中老化残留的降解受到明显抑制,但水稻根系仍可吸收利用并向地上组织传输,因此不可低估老化残留的生物有效性。在新施入DDT的处理中,水稻根系对DDD的吸收量高达900 ng g-1,不过,根系向地上部组织传输DDX的能力极为有限。值得注意的是:水稻根系对土壤中DDMS和DDMU吸收的生物富集因子为DDD或DDE的3倍,表明DDMU和DDMS具有较母体化合物更为突出的作物可吸收利用性。DDX各组分从水稻根系向地上组织传输时,其分布状况发生了明显的变化,引起这种变化的主要原因是作物在吸收和传输DDX时具有一定的选择性,或者DDX在这种吸收和传输过程中发生了进一步的降解。     

Effects of rhizosphere and long-term fertilisation practices on the activity and community structure of ammonia oxidisers under double-cropping rice field

The potential nitrification activity (PNA), population size and composition of AOB and AOA communities in both rhizosphere and bulk soil from a long-term (32 year) fertiliser field experiment conducted during early rice and late rice seasons were investigated by using the shaken slurry method and quantitative real-time polymerase chain reaction. The experiment begins in 1986, and including five treatments: without fertiliser input, chemical fertiliser alone, rice straw residue and chemical fertiliser, low organic manure rate and chemical fertiliser and high organic manure rate and chemical fertiliser. The results showed that the application of chemical fertiliser greatly enhanced PNA and AOB abundance, while application of rice straw residue and organic manure increased AOA abundance. Moreover, the results showed that the PNA and population sizes of AOB and AOA were higher in the rhizosphere than in the bulk soil. Cluster and redundancy analyses further indicated that the rhizosphere effect play a more important role in shaping AOA community structure than long-term fertilization. In summary, the results indicated that AOB rather than AOA functionally dominate ammonia oxidation in the double-cropping rice paddy soils, and that rhizosphere effect and fertiliser regime play different roles in the activity and community structures of AOB and AOA.     

田间旱育条件下不同化感潜力水稻根际土壤酚酸类和萜类物质分析

酚酸类和萜类是水稻化感作用研究中研究较多、争议较大的2大类化感物质,但目前有关水稻根系分泌物的研究多在实验室条件下进行。本文以国际公认的强化感水稻‘PI312777’和弱化感水稻‘Lemont’为材料,以未种植水稻的土壤为对照,研究了其在田间旱育条件下,不同土壤水分状态(旱地和湿地)时,根际土壤酚酸类和萜类物质的差异。结果表明,不同水分条件下不同化感潜力水稻品种和对照根际土壤中酚酸类物质和萜类物质的组成较为相似,但各物质含量存在一定差异。适度旱胁迫下,各处理根际土壤中所检测到的咖啡酸、对羟基苯甲酸、香草酸、阿魏酸和肉桂酸5种酚酸类物质及总量均有提高,其中强化感水稻‘PI312777’根际土壤中5种酚酸类物质提高最显著,比CK湿地处理提高2.84倍;在各处理根际土壤共检测到的27种萜类物质中,17种是含氧单萜;干旱胁迫导致各处理根际土壤单萜烯、含氧单萜、含氧倍半萜和总萜变化程度和变化趋势不同,单萜烯相对含量在强化感水稻‘PI312777’根际土壤中明显提高,而在弱化感水稻‘Lemont’和对照根际土壤中则降低。本文在此基础上讨论了由此导致2种水稻田间化感抑草效果差异的原因与机制。     

多菌灵在水稻及土壤中的消解动态和残留规律研究

采用田间试验方法,研究了多菌灵在稻田水、土壤和稻秆中的消解动态,测定了多菌灵在水稻和土壤中的最终残留量。样品采用甲醇和稀盐酸的混合溶液提取,经液-液分配净化,HPLC紫外分析测定。结果表明,田水、土壤、稻秆、谷壳、糙米中多菌灵添加浓度为0.05~1.0mg·kg-1时,平均回收率为83.16%~95.44%,变异系数在1.23%~5.32%之间,方法的最低检测浓度为：田水0.005mg·L-1,土壤0.005mg·kg-1,稻秆0.050mg·kg-1,谷壳0.050mg·kg-1,糙米0.025mg·kg-1。多菌灵在田水、土壤和稻秆中的消解动态均符合一级动力学方程,半衰期分别为2.53~3.41d、6.20~7.27d、3.27~3.91d,原始沉积量与施药量、施药次数密切相关。以231g·hm-2和346.5g·hm-2间隔7d施用多菌灵2次和3次,末次施药21d后多菌灵的最高残留量为：土壤未检出（≤0.005mg·kg-1）,稻秆0.524mg·kg-1,谷壳0.528mg·kg-1,糙米未检出（≤0.025mg·kg-1）。多菌灵在稻秆和谷壳中的残留量相对较高,以该稻秆和谷壳作为饲料有一定的风险;多菌灵在糙米中的残留量低于我国和食品法典委员会（CAC）及日本的最大残留限量（MRL）标准。     

Effect of Potassium Nutrition of Different Varieties of Rice on the Redox Status in Microzone Rhizosphere Soils

Being divided into three groups-strong,moderate and weak-according to the different kinetic parameters (Fmax,km,Cmin) of potassium uptake by crops,21 cultivars of rice have been studied to find out the relationships between their potassium nutrition and the oxidation-reduction status in the rhizosphere soils. Results show that,with no application of K fertilizer,there were higher contents of active reducing substances and ferrous iron in rhizosphere soils planted with cultivars,such as Zhongguo 91,week in absorbing potassium than in soils cropped with cultivars,Shanyou 64,stronger in absorbing potassium.As a result of K application,however,these toxic substances were decreased appreciably in the soil,particularly in the root zone where weakly K-absorbing sultivars were growing,and the parameter of soil redox (pH pE) was increased,the most striking example of this being found in the rhizosphere soil where the more strongly K-absorbing sultivars were growing.On and close to the root surface in soils where rice plants were supplied with potassium fertilizer,rather more iron oxide had been accumulated compared with rice receiving no potash,and even greater amounts of red iron oxide precipitated on the rice root in neutral paddy soils.As shown by the concentration distribution of active reducing substances and ferrous iron in a microzone of the profile,the redox range of rice roots supplied with potassium may extend as far as several centimeters from the root surface.It can thus be seen that potassium nutrition exerts its effect first on the morphological properties of rice roots and their exudation of oxygen,then on the content of soluble oxygen and the count and species of oxygen-consuming microbes in the rhizosphere soil,and finally on the redox status of the soil.     

水稻根际氮素状况及其利用

A greenhouse pot experiment was conducted with hybrid rice(Oryza Sativa L.) in order to study N Status and utilization in the rhizosphere of rice,The experiment was composed of three treatments:without N,15NH4-N and 15NO3-N .Plant roots were separated from the soil by a nylon cloth,and 1 mm increments of soil,moving laterally away from the roots,were taken and analyzed for various N froms.The labelled N in the plants ranged from 67\51%to 69.24% of the total amount of N absorbed by the rice seedlings with the labelled fertilizer N treatments.This shows that the N in the Plants came mainly from the fertilizers.However,the N absorbed by the rice seedlings accounted for less than 35% of the total amount of the N depletion in the soil near the rice roots,indicating an important N loss in the rhizosphere of rice.The soil redox potential(all treatments)and the concentration of the labelled NO3-N(the labelled NH4-N treatment only) decreased as the distance from the rice roots increased in the rhizosphere of rice.In contrast,the concentration of the labelled NH4-N increased as the distance uincreased in the same soil zone.These results suggested that nifrification occurred in the soil around the rice roots.Therefore,the reason for the N loss in the rhizosphere of rice might be the NO3 movement into the reductive non-rhizosphere soil(submerged) where denitrification can take place.