【作者】 肖红；

【导师】 周启星；

【作者基本信息】 中国科学院研究生院（沈阳应用生态研究所） ， 生态学， 2004， 博士

【摘要】 作为常用的除草剂和氮肥,乙草胺、尿素在黑土区广泛应用。本文就乙草胺和尿素单一及复合污染对黑土农田的生态毒理效应及机理进行研究,为黑土区农业持续发展提供理论参考。乙草胺和较高浓度的尿素均对蚯蚓有毒害作用,可导致蚯蚓体重下降及死亡;污染胁迫引起生物体生内产生大量O2-等自由基,抗氧化酶系中两种关键酶SOD和POD活性受活性氧自由基诱导而应激性升高,可溶性蛋白含量下降,过高浓度则将导致酶系崩溃,生物死亡。乙草胺和较高浓度的尿素均对小麦和白菜的发芽、根伸长及幼苗生长有毒害作用,可降低发芽率,抑制其根、芽的伸长;乙草胺导致小麦叶片叶绿素和可溶性蛋白含量降低,对SOD和POD活性则表现为先诱导后抑制;低浓度尿素能增加小麦叶绿素及蛋白质含量,提高SOD和POD活性,但高浓度导致小麦叶片叶绿素、可溶性蛋白含量及SOD活性降低,POD活性进一步升高,影响生物膜的生物合成及完整性,使植株生长受阻,甚至枯死。乙草胺对黑土土壤微生物有不同程度的抑制作用,低浓度下可较快恢复,高浓度与此相反。乙草胺、尿素均为低浓度促进黑土呼吸作用,浓度升高则促进作用减弱。二者的联合作用多呈现为低浓度尿素可部分拮抗乙草胺的毒性作用,高浓度尿素则强化乙草胺的毒害作用,表现为协同作用。更多还原

【Abstract】 As staple herbicide and nitrogenous fertilizer, acetochlor and urea have been widely used in phaeozem. Single and joint effects and mechanism of excessive acetochlor and urea on eco-system in phaeozem thus were investigated, aimed to provide theory references for continuable agriculture in the area.Acetochlor and high concentration urea were toxic to earthworms,leading their mortality and weight decreasing. Pollutions result in soluble protein content decreased. The activities of SOD and POD rise first reducing by pollutions, and decreased afterward with the higher concentrations. Then, non-reversible damage was induced and deadness happened.Acetochlor and high concentration urea had bad effects on germination, shoot and root elongation and seedling. Soluble protein and chlorophyll contents decreased with the increasing concentration of acetochlor. The activities of SOD and POD rise first reducing by pollutions, and decreased afterward with the higher concentrations. Low concentration of urea could increase soluble protein and chlorophyll contents and activity of SOD and POD, while urea of high concentration would induce the decrease of soluble protein and chlorophyll contents and activity of SOD, increase POD activity. That would destroy cellular membrane, stunt seedling and even wither away.Acetochlor showed various degrees of damage to microorganisms in soil. Effect of low concentration acetochlor could resume in a relative short time, it was contrary when concentrations were high. Soil respiration increased when concentrations of acetochlor and urea were low and decrease with high concentrations.Combined effects were antagonism when concentration of urea was low, while synergism when concentration of urea was high.更多还原