Due to the presence of multiple pollutants including metals in natural environments , studies on joint - action toxicity are becoming increasingly popular . these studies are indispensable to measuring and predicting impacts of chemical pollutants on organism . however , studies of the joint toxicity of pesticides and metals in the aquatic ecosystem were few 因此，有关预测和治理化学污染物对生物产生毒性的联合作用研究，已越来越受到大家的关注，特别是对农田水系农药和重金属等主要污染物共存时的生物效应与机理方面的研究。
The population distribution of physiological groups of bacteria ， including ammonifying bacteria , denitrifying bacteria , nitrobacteria and nitroso bacteria , organic phosphate dissolving bacteria and inorganic phosphate dissolving bacteria in water body and sediment of suzhou creek are studied with mpn and flat account method from jan . 2002 to mar . 2003 . the role of these physiological groups of bacteria in suzhou creek aquatic ecosystem is discussed 用最大可能数( mpn )法和平板计数法，于2002年1月2003年3月对苏州河水体和底泥中的主要微生物功能菌群? ?包括有机磷分解菌、无机磷分解菌、氨化菌、亚硝化菌、硝化菌和反硝化菌等进行了生态调查，并分析探讨了它们在苏州河水生态系统中的作用。
