速灭菊酯在水稻-水-鱼系统中的动态

采用同位素示踪技术和模拟生态系统试验法,对水田施用速灭菊酯后对邻近水域的污染、水域中鱼类对速灭菊酯残留物的浓缩和排除等进行了研究,结果表明,在田表水中,残留物浓度随处理后时间而迅速降低。水系中淤泥对水中残留物有明显的吸附净化作用,鱼对水中速灭菊酯残留物的摄取和排除均很迅速。 用二室模型对速灭菊酯残留物在田表水中的消失、用一级输入和输出的单室模型对鱼体中残留物浓度随时间的变化动态研究表明,在田表水中,土壤对水中残留物起着强烈的吸附净化作用;在水系中,鱼体中残留物浓度的消长主要取决于残留物自身在水中的消失速率,只是在前期同时依赖于鱼体对残留物的排除效应,鱼体的摄入常数只对鱼体累积浓度最大值及到达最大值的时间T_m产生影响。     

Photodegradation mechanism of deltamethrin and fenvalerate

To understand the degradation and environmental fate of pyrethroids, the process of their photodegradation under simulated natural conditions was investigated. The results showed that the degradation process follows first-order kinetics. The degradation intermediates were identified with gas chromatography-mass spectrometry. A plausible mechanism was discussed to explain the process. Several influences on degradation process were investigated and reported such as the e ects of initial concentration of pyrethroids, total time of light irradiation, solvents, and light source, as well as the e ect of a few substances that exist in the environment. This study could be a good reference for the degradation of pyrethroids in practical circumstances.     

利用N-乙酰-β-D-氨基葡萄糖苷酶含量评价农药对花翅摇蚊种群发育的影响

为了进一步探索种群水平的生态风险评估方法,本文利用β-N-Acetyl-D-glucosaminidase(NAGase)的变化量来监测农药对摇蚊种群发育的影响。从花翅摇蚊Chironomus kiiensis体内分离纯化得到电泳纯的NAGase,并通过免疫大白兔制得NAGase的多克隆抗体。运用间接非竞争ELISA法检测抗体特异性,结果表明其与共同存在于水体的一些生物的NAGase的交叉反应率为隆线溞4.41%、老年低额溞3.12%、多刺裸腹溞3.40%、中华薄壳介4.17%、日本沼虾3.23%、白纹伊蚊7.50%、小球藻0.5%。运用抗体测得毒死蜱、氰戊菊酯和阿维菌素3种杀虫剂对于摇蚊NAGase释放量的12 d-EC50分别为1.2012、0.0043和0.6281μg·L-1,以NAGase活力作为测试终点,测得相应的12 d-EC50:1.4765、0.0051和0.6756μg·L-1,两者差异不显著,但均显著低于以死亡作为测试终点的12 d-LC50:4.8171、0.0954和2.1340μg·L-1,且毒力大小均为氰戊菊酯阿维菌素毒死蜱。上述结果表明,利用NAGase多克隆抗体可以特异性地检测农药对花翅摇蚊种群发育的影响。     

氰戊菊酯对河川沙塘鳢幼鱼的毒性效应

采用静水生物测试法,研究了氰戊菊酯(fenvalerate,FEN)对河川沙塘鳢(Odontobutis potamophila)幼鱼的毒性效应.结果显示,FEN对河川沙塘鳢幼鱼的24、48、72和96 h(t)的半数致死质量浓度ρ(LC50)(95％置信区间)分别为(3.19±1.38)、(1.66±1.02)、(0.98±0.69)和(0.70±0.49) μg·L-1,变化规律符合指数衰减模型ρ(LC50) =0.915 1 +15.012 3 ×exp(-0.075 8 ×t)(r=0.996 2),安全浓度为(0.13±0.97) μg·L-1.半数致死时间t(LT50)表现出显著的剂量[ρ(FEN)]效应,可用方程t(LT50) =2 653.467 6 ×exp[-5.590 4 ×ρ(FEN)]+56.378 7 ×exp[-0.209 5×ρ(FEN)](r=0.999 4)对其进行拟合.双因素方差分析显示,肝脏过氧化氢酶(CAT)、超氧化物歧化酶(SOD)活性及丙二醛(MDA)含量随FEN浓度的增加和暴露时间的延长而均呈显著变化(P＜0.05),但两个因素的交叉影响不显著(P＞0.05).暴露24 h时,4μg· L-1浓度组SOD和CAT活性达到峰值,随后开始下降,而此时各浓度组MDA含量无显著变化(P＞0.05),48和96 h时,4、6和10 μg·L-1浓度组MDA含量则表现为显著上升.暴露时间和FEN浓度的交互作用对鳃Na+ /K+-ATP酶活性影响显著(P＜0.05),暴露24、48和96 h时,高浓度(6和10 μg·L-1)组Na +/K+-ATP酶活性均呈现显著下降;上述指标可较好地用于评价FEN的毒性效应.组织病理观察发现,FEN污染对河川沙塘鳢幼鱼的鳃、肝脏均造成严重损伤:鳃丝紊乱,上皮细胞增生,柱状细胞破裂;肝细胞实质空泡化,胆管内皮细胞肥大、融合.     

Acute toxicity of the synthetic pyrethroid pesticide fenvalerate to some air breathing fishes

Lethal concentrations (LC₅₀) of a synthetic pyrethroid pesticide, fenvalerate, for three species of air breathing fish Clarias batrachus, Channa punctatus and Heteropneustes fossilis were determined under water and acetone soluble condition in the laboratory using the static bioassay procedure of the American Public Health Association (APHA,1995). Acetone soluble fenvalerate was found more toxic than the water-soluble fenvalerate irrespective of species and exposure periods. The LC₅₀ value upon 96 days exposure to acetone soluble fenvalerate for C. batrachus, Channa C. punctatus and Heteropneustes H. fossilis were 1.35, 1.0 and 0.65?µg?L^?1, respectively. It is concluded from the present study that fenvalerate is highly toxic even to the hardy air breathing fishes and the pesticide, when dissolved in water, remains photostable and active to render toxicity for long duration.     

Alterations in Carbohydrate Metabolism in Selected Tissues of Crab, Oziotelphusa Senex Senex (Fabricius) Under Fenvalerate-Induced Stress

Changes in carbohydrate metabolism in hepatopancreas and muscle of the crab, Oziotelphusa senex senex exposed to a sublethal concentration (0.2 ppm) of fenvalerate, a pyrethroid insecticide, were studied. the glycogen and total carbohydrate levels decreased significantly in the tissues of crab exposed to fenvalerate. an increase in phosphorylase 'a' and decrease in aldolase activity levels suggested increased glycogenolysis, and decreased glycolysis during fenvalerate toxicity. Krebs cycle enzymes such as NAD-isocitrate dehydrogenase, succinate dehydrogenase and malate dehydrogenase were decreased, suggesting reduced mitochondrial oxidative metabolism. Glucose-6-phosphate dehydrogenase activity was increased significantly, indicating enhanced oxidation of glucose through the hexose monophosphate shunt pathway. Lactate dehydrogenase activity was elevated indicating the development of anaerobic conditions at tissue level in the stressed crab. Cytochrome C oxidase and Mg2+ ATPase activity levels were also decreased, indicating the impaired energy synthesis and prevalence of energy crisis. These results suggest that fenvalerate has a profound effect on the glucose metabolism of crab.     

Toxicity of the pyrethroid pesticide fenvalerate to freshwater catfish clarias gariepinus: Lethality,biochemical effects and role of dietary ascorbic acid

Static bioassays were made in the laboratory to determine lethal concentration of the pyrethroid pesticide fenvalerate [(RS)-alpha-cyano-3-phenoxybenzyl (RS)-2-(4-chlorophenyl)-3-methylbutyrate] for the freshwater catfish Clarias gariepinus and effects of sublethal concentrations of the pesticide on some biochemical parameters of the fish. For exposure periods of 24 to 96 h, LC₅₀ values of fenvalerate ranged from 5.83–4.76 μ g/L and 4.24–2.94 μ g/L, respectively for water and acetone soluble fenvalerate. Two sublethal concentrations of fenvalerate were used in the bioassays for biochemical parameters: 2.1 μ g/L for 24 h and 1.4 μ g/L for 96 h exposure, both concentrations representing 50% of LC₅₀ value of acetone soluble fenvalerate for the respective exposure period. Hepatosomatic index, liver glycogen, alkaline phosphatase of liver and ascorbic acid of blood, liver, and kidney decreased while haemoglobin (Hb) %, plasma glucose levels and acid phosphatase level of liver increased after 24 h exposure to 2.1 μ g/L fenvalerate. Longer exposure (96 h) to even a lower concentration (1.4 μ g/L) of fenvalerate resulted in reduction of all the parameters (except Hb %) tested as compared with control. Fish previously fed for 60 days with a diet supplemented by a high level of ascorbic acid (100 mg/100 g diet) could reverse most of the effects caused by 24 h exposure to 2.1 μ g/L fenvalerate. A lower level of ascorbic acid (50 mg/ 100 g diet) supplement could not influence these effects of fenvalerate. Even the higher dose of ascorbic acid supplementation (100 mg/100 g diet) could not relieve the stress parameters, except for Hb% and HSI, when the pesticide was applied at 1.4 μ g/L for a longer time period (96 h).     

氰戊菊酯和锐劲特对原生动物群落的联合毒性试验研究

氰戊菊酯和锐劲特两种农药被广泛用于茶树、果树、水稻、蔬菜等的病虫害防治,它们同时出现在同一环境中的机会非常多,但有关两种农药对生态系统的复合毒性效应却未见有研究报道.与单种生物毒性试验相比,群落级生物毒性试验对毒物胁迫的反映更具环境真实性.以PFU在天然淡水中采集到的原生动物群落为靶生物,研究了氰戊菊酯和锐劲特2种农药对淡水原生动物群落的毒性效应,对于水生生态环境的保护有特殊的意义.研究结果表明,2种农药单独存在时对原生动物群落的48h半数致死浓度分别为15 93mg·L-1和35 83mg·L-1;2种物质以等毒性比(单一LC50的比值)混和,进行联合毒性试验研究,用Marking相加指数法进行评价,其AI值为0 9,表现为协同作用.氰戊菊酯和锐劲特进入水环境后,将使水环境中原生动物群落的结构和组成发生变化,原生动物种类数减少,群落结构变得简单.在所有种类中,纤毛虫受损最大,水生生态系统的物质循环和能量流动将会受到一定程度的影响.     

毒死蜱、马拉硫磷和氰戊菊酯对赤子爱胜蚓（Eisenia foetida）的急性毒性

采用滤纸接触法和土壤培养法研究了毒死蜱(Chlorpyrifos)、马拉硫磷(Malathion)和氰戊菊酯(Fenvalerate)对赤子爱胜蚓(Eisenia foetida)的急性毒性效应.滤纸接触法试验浓度分别设置为,毒死蜱:3.14、6.28、9.42、12.56、15.70、18.84μg·cm-2;马拉硫磷:3.10、6.20、12.40、18.60、24.80、31.40μg·cm-2;氰戊菊酯:0.31、0.62、1.24、1.86、2.48、3.14μg·cm-2.土壤培养法试验浓度分别设置为,毒死蜱:100、125、150、175、200、225、250mg·kg-1;马拉硫磷:350、400、450、500、550、600mg·kg-1;氰戊菊酯:20、30、40、50、60、70、80mg·kg-1.结果表明:采用滤纸接触法测得的各农药对蚯蚓48h的半数致死浓度(LC50)分别为毒死蜱12.26μg·cm-2、马拉硫磷19.61μg·cm-2、氰戊菊酯1.03μg·cm-2;采用土壤培养法测得的各农药对蚯蚓7d的LC50分别为毒死蜱427.67mg·kg-1、马拉硫磷742.53mg·kg-1、氰戊菊酯81.81mg·kg-1,14d的LC50分别为毒死蜱182.21mg·kg-1、马拉硫磷497.29mg·kg-1、氰戊菊酯37.46mg·kg-1.根据《化学农药环境安全评价试验准则》,这3种农药对蚯蚓的毒性均为低毒级.     

一株能同时降解邻苯二甲酸二丁酯(DBP)和氰戊菊酯真菌的分离、鉴定及降解特性的初步研究

采用富集培养法从农田土壤中筛选出1株可同时降解邻苯二甲酸二丁酯(DBP)和氰戊菊酯的真菌DY4,经形态、生理生化特征及26S r DNA序列分析,初步鉴定为地霉属(Geotrichum sp.)霉菌,并在纯培养条件下研究了该菌株的最优降解条件和降解特性.结果表明,菌株DY4可利用DBP或氰戊菊酯作为唯一碳源,DBP、氰戊菊酯单一存在时,7 d对50 mg·L-1DBP的降解率(84.13%)高于氰戊菊酯(37.07%)的;DBP、氰戊菊酯共存时,对DBP的降解率明显降低,可能是农药对微生物的毒害作用所致.正交试验得到菌株DY4的最优降解条件为无外加碳源、DBP和氰戊菊酯的初始浓度25 mg·L-1、p H 7.5,在此条件下,7 d对DBP和氰戊菊酯的降解率达到65.36%和55.77%,降解反应符合一级动力学方程模型,两者的半衰期为4.46和6.88 d.