Effects of a simulated agricultural runoff event on sediment toxicity in a managed backwater wetland

We examined the effects of an amended mixture of three pesticides, atrazine (72.7 g), S-metolachlor (54.5 g), and permethrin (both cis and trans isomers; 11.4 g), on 10-day sediment toxicity to Hyalella azteca in a managed natural backwater wetland after a simulated agricultural runoff event. Sediment samples were collected at 10, 40, 100, 300, and 500 m from inflow 13 days prior to amendment and 1, 5, 12, 22, and 36 days post-amendment. Background pesticide concentrations ranged from