Release of atrazine (C-14) from two undisturbed submerged sediments over atwo-year period

Through water erosion and runoff, sediment-adsorbed atrazine can undergo se dimentation and accumulation at the bottom of water bodies and become poten tial sources of atrazine to the water column. The purpose of this study is to determine the fate and release of atrazine (C-14) to the water column fr om two simulated undisturbed submerged sediments at two temperature treatme nts (5 and 24 degrees C) over a 2-year period. Atrazine residue (C-14) was released from the two sediments and was, primarily, diffusing from the sedi ment pore water to the water columns. The amount released was affected by s ediment type and is related to the sediment's adsorption/desorption capacit y. Larger amounts of residue (C-14) Were released to the water columns at 5 degrees C than at 24 degrees C. Atrazine degraded in the shallow submerged anaerobic sediment's water columns over the 2-year period. Less than 2% (p ercent of applied in atrazine equivalent) of extractable atrazine and metab olites remained in the sediment after 2 years. The amount of nonextractable atrazine residue (C-14) was significantly higher in sediments at 24 degree s C than at 5 degrees C. In conclusion, atrazine accumulating in shallow un disturbed submerged sediments from nonpoint sources would most likely degra de and/or become nonextractable over time and would have a low probability of becoming a significant source to the water body. The conditions where ac cumulation and future release of atrazine have a greater potential to occur are under very cold temperatures with low adsorption capacity sediments.