单甲脒农药对模型池塘生态系统群落结构的影响

在３ｍ×１ｍ×１ｍ（Ｖ＝３ｍ３）含有底泥的模型池塘生态系统中研究单脒农药对水生生物群落结构的影晌。规定实验浓度力０、１．５、３．０、６．０和１２．０ｍｇ／Ｌ，每１５ｄ加入１次２５％单甲脒农药水剂，连续加入４次，实验进行２个多月。在实验浓度范围内，童甲脒农药对水生生物群落产生不同程度的影响。浮游生物比较敏感：加药后头几天内，种类、数量及多样性指数下降，浓度越大，影响越明显；大约１周以后，各处理组浮游生物群落逐步得到恢复，实验后期其数量甚至可超过对照水平，但群落结构发生改变，敏感种类少或消失，耐污种类增加，生物多样性降低。底栖生物比较耐污：处理槽大型水生植物的叶绿素含量有所减少，但其种类和生物量未见明显差异；底栖动物种类、数量也未见明显变化。微生物最耐污，在处理槽水层及沉积物中好氧异养菌数量有所增加，沉积物中厌气菌数量也有增加的趋势。青鱼对单甲脒农药较敏感，在１．５ｍｇ／Ｌ以下浓度尚能正常存活和繁殖。单甲脒农药水剂明显增加水体氮、磷含量，尤其磷酸盐含量高，使水体氮、磷比例失调，可能导致水体富营养化。根据综合指标分析，在规定单甲脒盆酸盐浓度＜１．５ｍｇ／Ｌ的实验条件下，水生生物群落结构未见明显改变．

EFFECTS OF N'-(2,4-DIMETHYLPHENYL)-N-METHYLFORMAMIDINE HYROCHLORIDE ON COMMUNITY STRUCTURE IN POND MESOCOSMS

Effect of Monoformamidine insecticide,N'-(2,4-dimethylphenyl)-N-methylformamidinehydrochloride(DMAH),on the aquatic community structure were experimentallyinvestigated through glass fibre glass fibre tanks with a dimension of 3m×1m×1m(V=3m)under outdoor conditions in Beijing,1993. The nominal concentration of 0,1.5, 3. 0, 6.0 and 12.0mg· L-1 were dosed to test tanks,respectively, once two weeks. The experiment ran for 2months. The results indicate that the DMAH was toxic to aquatic community. Plankton comun...