Herbicides in Kansas Waters - Evaluations of the Effects of Agricultural Runoff and Aquatic Weed Control on Aquatic Food Chains

摘要

Experimental ponds were used for studying the effects of an agricultural herbicide on aquatic food chains. Atrazine, one of the most heavily used herbicides in Midwest agriculture, was added to ponds and the ensuing responses were followed through four months. With single 20 mu g/liter additions to the ponds, effects were recorded throughout the food chain. After one day of exposure rates of phytoplankton photosynthesis declined at both levels, with the higher level causing an almost complete inhibition. Phytoplankton succession was altered within a few days at both levels, with resistant species increasing in abundance. Some members of the aquatic food chain were unaffected, particularly the benthic insects, although effects were recorded at the highest level of these food chains, the fish.