有机磷农药对锯齿新米虾的毒性及敏感性分析

以锯齿新米虾为受试生物,研究了敌敌畏、马拉硫磷、对硫磷、甲基对硫磷和乐果5种有机磷农药对锯齿新米虾(Neocaridina denticulate)暴露时间为4d的急性毒性和28d的慢性毒性.结果表明,敌敌畏、马拉硫磷、对硫磷、甲基对硫磷和乐果对锯齿新米虾的96h半数致死浓度(96h-LC_(50))分别为34.100,846.408,7.736,4.132,1606.875ng/L.28d无可观测效应浓度(NOEC)分别为0.991,7.755,0.269,0.222,100ng/L.28d最低可见效应浓度(LOEC)分别为1.388,15.200,0.404,0.333,200ng/L.锯齿新米虾对乐果和对硫磷相对不敏感,对马拉硫磷和甲基对硫磷不敏感,对敌敌畏较敏感.研究结果可为5种有机磷农药的水生生物基准的制定及环境风险评估提供科学依据.     

粤桂琼区域水源地有机磷农药的生态风险评价

利用气相色谱-质谱检测粤桂琼(广东、广西、海南三省区)区域水源地9个采样点水样中的有机磷农药浓度,构建了淡水生物对有机磷农药的物种敏感性分布,并计算出各类水生生物的HC₅(hazardous concentration for 5% the species)值;采用基于浓度加和模型的混合物风险商值法和商值概率分布法,评价了粤桂琼区域水源地中敌敌畏、内吸磷、阿特拉津、甲基对硫磷、乐果、马拉硫磷和对硫磷7种有机磷农药的的生态风险,同时利用聚类分析法对9个采样点进行了生态风险评价. 结果表明:粤桂琼区域水源地7种有机磷农药的总质量浓度在nd~1 260.95 ng/L之间,平均值为184.68 ng/L,主要以马拉硫磷、甲基对硫磷、对硫磷和乐果为主. 东莞东江南支流、玉林苏烟水库和柳州柳江水源地的生态风险级别相对较高. 敌敌畏、对硫磷、甲基对硫磷的HC₅值均低于0.1 μg/L,这3种物质对生态系统毒性效应较大. 根据风险商结果排序可知,粤桂琼区域水源地预防的重点为甲基对硫磷、对硫磷和马拉硫磷对水生生物的危害,其中甲基对硫磷是对混合风险商贡献最高的污染物,其危害指数达21.313;在95%的置信区间内,甲基对硫磷、对硫磷和马拉硫磷的生态风险较大,风险商超过1的概率为5%,应作为最优先控制的污染物.      

气相色谱法测定海洋生物体中有机磷农药残留

建立了气相色谱法测定海洋生物体中乐果、甲基对硫磷和马拉硫磷残留量的方法.海洋生物体中有机磷农药残留用丙酮经超声波提取、弗罗里硅土净化后,用DB-1701毛细管色谱柱分离,火焰光度检测器(FPD)直接测定.在鱼、虾、贝类等样品中添加浓度为0.008×10-6、0.08 ×10-6和0.8×10-6的回收率(n=11)范围为72.6%～112%,相对标准偏差(RSD)为5.7%～9.0%,乐果、甲基对硫磷和马拉硫磷的检出限分别为0.002×10-6、0.002×10-6和0.004×10-6.本方法具有灵敏、快速、简便等特点,能满足海洋生物体中有机磷农残的监测要求.     

马拉硫磷农药污水处理

马拉硫磷的用处马拉硫磷是一种高效低毒的有机磷农药,在农业、卫生方面用途十分广泛。用50％的马拉硫磷乳油,兑水500倍,作喷雾用,可以防治稻飞(?)、棉蚜虫、黄守瓜、红蜘蛛、斜纹夜蛾和蔬菜蚜虫。兑水1000倍,可以防治蓟马,金龟(?)、潜叶蝇、果树食心虫等。它是水稻、棉花、蔬菜、高粱、果树、森林的重要杀虫剂。马拉硫磷以低毒为特点,毒性比敌敌畏低     

敌敌畏的臭氧氧化处理

在12 L的反应器中,观察了臭氧浓度分别为4.9、6.7和7.6 mg/L,溶液温度10.50℃,pH值为3.1、5.3、7.2、9.4和11.2条件下,臭氧氧化浓度为30 mg/L的有机磷杀虫剂敌敌畏的处理效果,并计算了臭氧氧化敌敌畏的反应动力学.结果表明,臭氧氧化法是处理敌敌畏的高效方法.不同浓度臭氧处理5 min时敌敌畏的去除率均在96%以上,6.7 mg/L的臭氧氧化处理敌敌畏4 min时矿化度(以TOC 计)可达34.8%.臭氧浓度越高,敌敌畏的降解速率越快.随着敌敌畏初始浓度的升高,敌敌畏的氧化去除率下降,但绝对去除量升高.试验范围内的pH值和温度对敌敌畏的臭氧氧化去除效果影响不大.在臭氧浓度6.7 mg/L,pH 7.2和室温20℃的条件下,臭氧氧化敌敌畏的反应级数为0.11,反应速率常数k为7.72 mg·(L·min)-1.     

水体中多种有机磷农药残留量气相色谱分析方法

本文参阅有关文献,建立了水体中七种有机磷农药(敌敌畏、3911、地亚农、稻瘟净、马拉硫磷、对硫磷、乙硫磷)的GC-FPD分析方法.水样经有机溶剂萃取,浓缩到小体积,即可进行色谱分析,本法简易、快速、灵敏.为     

关于气相色谱法测定水中有机磷农药的不确定度评定

在中性条件下,二氯甲烷作为萃取剂,萃取水中的有机磷农药,用带火焰光度检测器(FPD)的毛细管柱气相色谱仪对其测量不确定度进行评定。不确定度的来源主要包括:前处理过程,标准溶液及其配制过程,校准曲线拟合,样品重复测定等。评定结果为有机磷农药(以马拉硫磷为例)的不确定度(44.5±5.32)μg/L,k=2。     

不同标准溶液测定定值样品中钒和锶

由于标准溶液的介质及介质浓度不用,所配制的标准系列存在体系间的差异.测定定值样品(水中)钒和锶,选用不同的标准溶液对样品的测定结果有着不同程度的影响.     

5种海鱼脑AChE对2种有机磷农药的敏感性比较

以鲈鱼、黄鱼、美国红鱼、真鲷和黑鲷为实验材料,采用半抑制浓度(IC_(50))和双分子速率常数(K_i)为指标,通过体外抑制作用比较了5种海鱼脑乙酰胆碱酯酶[AChE(EC 3.1.1.7)]对马拉硫磷和甲基对硫磷的敏感性。结果表明:(1)5种海鱼脑AChE基础活性为10.18～22.64[μmol/(min·g)],黄鱼的酶活性最高,鲈鱼的酶活性最低。(2)对马拉硫磷,由IC_(50)所得到的AChE敏感性为:黄鱼、鲈鱼、真鲷>黑鲷>美国红鱼;由K_i所得到的AChE敏感性为:鲈鱼、黄鱼、真鲷>黑鲷>美国红鱼。对甲基对硫磷,由IC_(50)所得到的AChE敏感性为:鲈鱼>黄鱼、真鲷、黑鲷>美国红鱼;由K_i所得到的AChE敏感性为:鲈鱼、黄鱼、黑鲷>真鲷>美国红鱼。鲈鱼和黄鱼对2种有机磷农药都较为敏感。(3)鱼脑AChE活力抑制作用与水体中的有机磷农药具有良好的剂量—效应关系。在1～100mg/L浓度范围内,两者间呈现较好的线性相关性,其相关系数基本上都在0.98以上。根据AChE的敏感性及其对有机磷农药的线性响应程度,黄鱼和鲈鱼脑AChE分别适于作为监测马拉硫磷和甲基对硫磷的指示酶。     

敌敌畏降解真菌的分离及其特性研究

从受过有机磷农药污染的污泥中分离到一株降解敌敌畏的真菌。经初步鉴定为木霉属,并命名为木霉FM10。该菌对敌敌畏的降解是同葡萄糖以共代谢方式进行的。葡萄糖浓度在1000μg/mL时,木霉FM10降解低地畏作用最强;敌敌畏初浓度越大降解率越低;菌株生长的最适pH为8.0,而pH9.0时,菌株降解率更高;37℃是菌株生长和降解敌敌畏的最适温度;增加接种量可以提高降解率;金属离子对所分离菌株一般表现为抑制作用。经分析,木霉FM10降解敌敌畏的酶多分布于胞外,属于分泌性酶。     

Evaluation of phytoextracting cadmium and lead by sunflower, ricinus, alfalfa and mustard in hydroponic culture

Soil contaminated with heavy metals cadmium(Cd)and lead(Pb)is hard to be remediated.Phytoremediation may be a feasible method to remove toxic metals from soil,but there are few suitable plants which can hyperaccumulate metals.In this study,Cd and Pb accumulation by four plants including sunflower(Helianthus annuus L.),mustard(Brassica juncea L.),alfalfa(Medicago sativa L.), ricinus(Ricinus communis L.)in hydroponic cultures was compared.Results showed that these plants could phytocxtract heavy metals, the ability of accumulation differed with species,concentrations and categories of heavy metals.Values of BCF(bioconcentration factor)and TF(translocation factor)indicated that four species had dissimilar abilities of phytoextraction and transportation of heavy metals.Changes on the biomass of plants,pH and Eh at different treatments revealed that these four plants had distinct responses to Cd and Pb in cultures.Measurements should be taken to improve the phytoremediation of sites contaminated with heavy metals,such as pH and Eh regulations,and so forth.     

Oxidation of As(Ⅲ) by potassium permanganate

The oxidation of As(Ⅲ) with potassium permanganate was studied under conditions including pH, initial As(Ⅲ) concentration and dosage of Mn(Ⅶ). The results have shown that potassium permanganate was an effective agent for oxidizing of As(Ⅲ) in a wide pH range. The pH value of tested water was not a significant factor affecting the oxidation of As(Ⅲ) by Mn(Ⅶ). Although theoretical redox analyses suggest that Mn(Ⅶ) should have better performance in oxidization of As(Ⅲ) within lower pH ranges, the experimental results show that the oxidation efficiencies of As(Ⅲ) under basic and acidic conditions were similar, which may be due to the adsorption of As(Ⅲ) on the Mn(OH)2 and MnO2 resulting from the oxidation of As(Ⅲ).     

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.     

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.     

Chlorobenzenes in waterweeds from the Xijiang River （Guangdong section） of the Pearl River

The Xijiang River is the major source of water for about 4.5 millions of urban population and 28.7 millions of rural population. The water quality is very important for the health of the rural population. The concentration and distribution of chlorobenzenes (CBs) in both water and waterweeds collected from 4 stations in the Xijiang River (Gangdong section) of the Pearl River in April and November were determined. The result showed that nearly every congener of CBs was detected. The total contents of CBs (∑CBs) in the river water ranged from 111.1 to 360.0 ng/L in April and from 151.9 to 481.7 ng/L in November, respectively. The pollution level of CBs in the water in April was higher than that in November. The contents of ∑ CBs in waterweeds ranged from 13.53×102 μg/g to 38.27×102μg/g dry weight (dw). There was no significant difference between April and November in waterweeds. The distribution of CBs in roots, caulis, and leaves of Vallisneria spiralis L. showed different patterns. The leaves mainly contained low-molecular-weight CBs(DCBs), whereas the roots accumulated more PCBs and HCBs. The average lgBCFlip (bioconcentration factor) of CBs ranged from 0.64 to 3.57 in the waterweeds. The spatial distribution character of CBs in the Xijiang River was: Fengkai County ＜ Yunan County ＜Yun'an County ＜ Gaoyao County according to the ∑CBs, and the pollution deteriorated from the upstream to the downstream of the Xijiang River. Further analysis demonstrated that the discharge of waste containing CBs may be the main source of CBs pollution in the Xijiang River.     

Degradation of 2,4-dichlorophenol with a novel TiO2/Ti-Fe-graphite felt photoelectrocatalytic oxidation process

Degradation of 2,4-dichlorophenol(2,4-DCP)was studied in a novel three-electrode photoelectrocatalytic(PEC)integrative oxidation process,and the factors influencing the degradation rate,such as applied current,flow speed of O_2,pH,adscititious voltage and initial 2,4-DCP concentration were investigated and optimized.H_2O_2 was produced nearby cathode and Fe~(2 )continuously generated from Fe anode in solution when current and O_2 were applied,so,main reactions,H_2O_2-assisted TiO_2 PEC oxidation and E-Fenton reaction,occurred during degradation of 2,4-DCP in this integrative system.The degradation ratio of 2,4-DCP was 93% in this integrative oxidation process,while it was only 31% in E-Fenton process and 46% in H_2O_2-assisted TiO_2 PEC process.So,it revealed that the degradation of 2,4-DCP was improved greatly by photoelectrical cooperation effect.By the investigation of pH,it showed that this integrative process could work well in a wide pH range from pH 3 to pH 9.     

Effect of copper on the degradation of pesticides cypermethrin and cyhalothrin

The influence of coexisting copper (Cu) ion on the degradation of pesticides pyrethroid cypermethrin and cyhalothrin in soil and photodegradation in water system were studied.Serial concentrations of the pesticides with the addition of copper ion were spiked in the soil and incubated for a regular period of time,the analysis of the extracts from the soil was carried out using gas chromatography (GC).The photodegradation of pyrethroids in water system was conducted under UV irradiation.The effect of Cu~(2 ) on the pesticides degradation was measured with half life (t_(0.5)) of degradation.It was found that a negative correlation between the degradation of the pyrethroid pesticides in soil and Cu addition was observed.But Cu~(2 ) could accelerate photodegradation of the pyrethroids in water.The t_(0.5) for cyhalothrin extended from 6.7 to 6.8 d while for cypermethrin extended from 8.1 to 10.9 d with the presence of copper ion in soil.As for photodegradation,t_(0.5) for cyhalothrin reduced from 173.3 to 115.5 rain and for cypermethrin from 115.5 to 99.0 min.The results suggested that copper influenced the degradation of the pesticides in soil by affecting the activity of microorganisms.However, it had catalyst tendency for photodegradation in water system.The difference for the degradation efficiency of pyrethroid isomers in soil was also observed.Copper could obviously accelerate the degradation of some special isomers.     

基于综合水质标识指数和对应分析法的校园河道水质评价

以三峡大学的校园河道求索溪为研究对象,利用综合水质标识指数法确定求索溪水质类别,分析其水质时空变化规律,并利用对应分析法得出求索溪中不同监测点的主要污染因子.研究结果表明:求索溪整体的综合水质标识指数为7.423,整体水质为劣V类(地表水环境质量标准GB 3838-2002)且黑臭.从时间变化来看,求索溪4月份的水质最差,5月份次之,4、5月份所有监测点的水质都劣于V类且黑臭;8月份水质最好,水质为Ⅳ类;从空间分布来看,8个监测点综合水质标识指数均超过6.0,水质为劣V类,其中6号监测点的水质相对最好,监测点3号的水质相对最差;对应分析法得出求索溪的整体水体污染程度受总氮因子的影响最大,其次为总磷.该研究拟为求索溪及类似校园河道的水环境治理研究提供基础依据和参考.