Impact of Land Use on Microbial Transformations of Atrazine
- C. Marjorie Aelion * and
- Dana C. Cresci
Atrazine has been one of the most heavily applied preemergent herbicides in the USA, and with alachlor, represents more than 45% (4.082 × 106 kg) of total herbicide application in coastal U.S. counties. Several studies using bacterial isolates or mixed cultures have demonstrated that mineralization of atrazine [6-chloro-N-ethyl-N′-(1-methyl-ethyl)-1,3,5-triazine-2,4-diamine] is rapid, yet in soil microcosms mimicking in situ conditions, mineralization accounts for <1% of the applied compound. This study examined the impact of land use on atrazine biotransformation in sediments from three coastal sites, all in an historically agricultural area that has undergone extensive development in recent years. Production of 14CO2 was monitored in sediment incubated with [U-14C]-atrazine from a forested preserve, a suburban neighborhood and a golf course, all of which were previously impacted by agriculture. Solid phase extraction of both liquid and sediment fractions was carried out over time to determine whether metabolic transformation of atrazine occurred. Results indicated that mineralization represented <1% of the atrazine added, and ring carbons were not assimilated into cellular biomass. Production of 14C-transformation products was a significant portion of the total 14C-atrazine added at all sites, but was greatest in the golf course sediments. This may be attributed to several environmental conditions of land development such as the preexposure of the golf course bacteria to frequent pesticide applications, and 100% sand content of the golf course sediment vs. higher clay and organic C content at the other two sites, causing less sorption and more bioavailability of atrazine.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
Copyright © . .