Monitoring of atrazine treatment on soil bacterial,fungal and atrazine-degrading communities by quantitative competitive PCR

We report the development of quantitative competitive (QC) PCR assays for quantifying the 16S, 18S ribosomal and atzC genes in nucleic acids directly extracted from soil. QC-PCR assays were standardised, calibrated and evaluated with an experimental study aiming to evaluate the impact of atrazine application on soil microflora. Comparison of QC-PCR 16S and 18S results with those of soil microbial biomass showed that, following atrazine application, the microbial biomass was not affected and that the amount of 16S rDNA gene representing 'bacteria' increased transitorily, while the amount of 18S rDNA gene representing fungi decreased in soil. In addition, comparison of atzC QC-PCR results with those of atrazine mineralisation revealed that, in response to atrazine treatment, the amount of atzC gene increased transitorily in soil pre-treated with atrazine, suggesting that accelerated atrazine biodegradation in soil could be due to a transient increase in the size of the atrazine mineralising community.     

阿特拉津对土壤过氧化氢酶活性的影响

采用室内培养方法,研究了阿特拉津胁迫对土壤中过氧化氢酶的活性的影响。结果发现:在培养期间,阿特拉津对土壤过氧化氢酶表现为明显的抑制作用。3种模型拟合阿特拉津浓度与酶活性关系均达到显著相关关系。土壤阿特拉津对过氧化氢酶的生态阈值的平均值为103mg/kg。     

除草剂阿特拉津影响大鼠脏器功能的毒理学研究

试验研究了除草剂阿特拉津对大鼠脏器功能的影响。选用SD大鼠120只．雌雄各半，随机分成4组．分别按每千克体重200mg，100mg，10mg，0mg，设置高、中、低剂量3个处理组和1个对照组，药物配成乳浊液灌胃．并于喂药15d和30d采样测定甲状腺、胸腺、心脏、肺脏、肝脏、脾脏、肾脏、生殖腺等脏器与体重的相对比值。实验结果表明：阿特拉津对动物的代谢器官(肝脏、肾脏)具有损伤作用，使其发生退行性病变，中、高剂量组损伤作用尤为明显；阿特拉津使大鼠的免疫器官——胸腺、脾脏发生退行性病变，高剂量组损伤作用最为明显；雄性大鼠睾丸发生退行性病变，雌性大鼠卵巢则出现增生性病变，进而可能影响到大鼠的生殖功能。     

藤黄微球菌AD3的阿特拉津降解基因检测与分析

为了获得高效稳定的阿特拉津基因,分离出更多的阿特拉津降解菌,试验采用PCR基因扩增和氮源利用方法,对AD3菌株的阿特拉津降解基因进行了检测和测序,并与其他菌株阿特拉津降解基因的序列进行了比较。结果表明：Micrococcus luteus AD3菌株含有阿特拉津降解基因trzN,atzB,atzC和atzDEF。其中trzN基因中心区的序列与Arthrobacter sp.TC1的trzN完全相同,atzB和atzC基因中心区的序列与Pseudomonas sp.ADP的atzB和atzC完全相同。AD3菌株能以氰脲酸为唯一氮源生长,Micrococcus luteus AD3菌株能将阿特拉津彻底降解成CO2和NH3。     

土壤表面阿特拉津的紫外光解动力学研究

采用田间土壤，在人工光解装置箱中研究了在紫外光照射下土壤表面阿特拉津的光解行为以及影响其光解行为的因素。实验测得阿特拉津的光解速率常数为0．0953～0．1864min，光解深度为0．10～0．23mm，半衰期为3．7～7.3min。研究结果表明，土壤粒度、pH值、有机物含量、土壤湿度、腐植酸含量及表面活性剂含量均会对阿特拉津在土壤表面的光解产生影响。     

固定在颗粒活性炭中的TiO_2光催化降解阿特拉津

利用30W低压汞灯作光源,采用固定颗粒活性炭中的TiO2(TiO2/GAC)作光催化剂,在浅盘反应器中考察了阿特拉津溶液的光催化降解。结果表明,在平均光强为4.38mW·cm-2,光催化剂投加量为7.0g·L-1,阿特拉津初始浓度为21.9mg·L-1,3wt%H2O2用量为30μL·15mL-1,投加方式为1次·2h-1,光照时间为6～10h时,去除率可达92.7%～94.7%,TOC去除率可达67.1%～78.3%。光催化剂增至10g·L-1,H2O2用量一次性加60μL,光照时间为3～4h时,去除率可达91.6%～93.7%,TOC去除率可达65.9%～73.9%。通过组合实验和紫外光谱图分析,估计了体系中影响去除率的光催化、吸附、光降解、H2O2的作用性质和大小,并估计了降解途径,认为同时存在侧链脱烷基反应和OH取代Cl的反应,在有H2O2存在时,使前反应较强。TOC值测定表明阿特拉津已从8个碳降至含2～3个碳的物质。     

添加莠去津的土壤中微生物生物量碳、氮、磷对外源有机无机物质的动态响应

研究了添加有机、无机营养物质对外加除草剂莠去津土壤(每1g土中含莠去津10mg/)中微生物生物量碳、氮和磷的动态变化过程。研究结果表明,在整个培养过程中,仅加莠去津的土壤中微生物生物量碳、氮、磷的含量均显著降低,与对照相比,分别平均降低了13.5%,10.1%,20.0%。但是,施用有机、无机营养物质的处理,土壤微生物生物量碳、氮、磷的含量均显著增加。不同处理对微生物生物量碳、氮的含量影响程度依次为:腐熟猪粪>紫云英>水稻秸秆腐熟猪粪>N、P肥配施>单施N肥>单施P肥。而对微生物生物量磷含量的影响则为:腐熟猪粪>N、P肥配施>紫云英>单施N肥>单施P肥>水稻秸秆。     

Prediction of field atrazine persistence in an allophanic soil with Opus2

A modified version of the model Opus was applied to measurements of soil water dynamics and atrazine (6-chloro-N2-ethyl-N4-isopropyl-1,3,5-triazine-2,4-diamine) persistence in a Bruntwood silt loam soil (Haplic Andosol, FAO system) in Hamilton, New Zealand. The modified model, Opus2, is briefly described and parameter estimation for the simulations is discussed. Soil water dynamics were more accurately described by applying measured soil hydraulic properties than by estimating them using pedotransfer functions. A parameter sensitivity analysis revealed that degradation was the most relevant process in simulating pesticide behaviour by Opus2. The Arrhenius equation incorporated in Opus2 did not correctly describe the effect of temperature on degradation rates obtained at 10, 20 and 30 degrees C. However, as the Arrhenius coefficient is a very sensitive parameter and soil temperature variation was relatively narrow in the field, the Arrhenius coefficient was approximated from the laboratory study. The simulation results obtained were superior to modelling at constant temperature. Field measured persistence of atrazine in the topsoil was underpredicted using the half-life determined in the laboratory at 10 degrees C. Modelling with a lag phase followed by accelerated degradation by use of a sigmoidal degradation equation in Opus2 significantly improved the modelling results. Nevertheless, degradation processes in the laboratory under controlled conditions did not accurately represent field dissipation, however well the laboratory degradation data could be described by simple kinetic equations. The study indicates the importance of improving field techniques for measuring degradation, and developing laboratory protocols that yield degradation data that are more representative of pesticide dynamics in field soils.     

小麦植株和麦田土壤莠去津残留气相色谱分析方法研究

本研究确立了乙腈振荡提取、弗罗里硅土SPE小柱净化小麦植株和麦田土壤中莠去津残留样本的前处理方法,建立了柱程序升温、GC-NPD残留样品检测方法.结果表明,优化色谱条件下,莠去津的色谱保留时间为5.97 min,在0.105～54.0 mg/L浓度范围内,莠去津浓度与其色谱峰面积在GC-NPD上线性响应良好,回归方程为Y=38.79X-120.34(R2=0.998 8).莠去津在小麦植株和麦田土壤中0.05～1mg/kg的3个水平的加标回收率均大于75％,各添加水平3次平行测定值的RSD均小于7％.其准确度和精密度均符合农药残留分析的要求.该色谱条件下仪器的最低检出量为0.38 ng,方法的最低检出浓度为0.018 mg/kg(植株)和0.021 mg/kg(麦田土壤),此检测灵敏度可以满足该农药在小麦植株和麦田土壤中残留的定量检测要求.     

多功能净化柱和固相萃取双重净化-液相色谱质谱法检测青贮饲料中莠去津及其代谢物的残留

采用多功能净化柱和MCX柱双重为样品的前处理方法,建立了青贮玉米中莠去津及其6种主要代谢产物的高效液相色谱质谱联用分析方法。试样经乙腈水提取,C18色谱柱梯度分离,并以基质匹配曲线外标法定量。结果表明:莠去津及其代谢物在2～100μg/kg范围内线性良好,标准曲线相关系数r均大于0.99。在2～50μg/kg浓度范围内,平均添加回收率在71.01%～113.34%,相对标准偏差为2.58%～15.46%,各目标物检出限(LOD)为1μg/kg,定量检出想(LOQ)为2μg/kg。本方法重现性好,准确度高,能够满足青贮玉米中残留检测的需要。