Soil acts as a major sink for bulk of the pesticides used in agriculture and public health programs. Leaching is a major transportation process responsible for ground water contamination, which is a major concern worldwide as ground water is a source of drinking and irrigation water in many countries. An Indian study demonstrates high mobility of imidacloprid in soil and high potential for leaching. Thiamethoxam also has a potential to leach down under heavy rainfall conditions.
Imidacloprid has relatively high water solubility (0.51 g/L) and low octanol-water partitioning coefficient [Log (Pow) = 0.57] which makes it an ideal case for studying its leaching potential in soil. The California EPA identified imidacloprid as a potential ground water contaminant based on its high water solubility (514 ppm), low Koc (262 cm3/kg), long hydrolysis half-life (30 days), long aerobic soil metabolism (half-life = 997 days) and long anaerobic soil metabolism (half-life = 27 days), see attached report. An Indian study demonstrates high mobility of imidacloprid in soil and high potential for leaching.
Bron: S Gupta et al. Bull Environ Contam Toxicol (2002) 68: 502-508
http://www.springerlink.com/content/9dmefx2wqum4bf4k/fulltext.pdf
Persistence and leaching of thiamethoxam in soil were studied under laboratory conditions. Thiamethoxam persisted beyond 90 days in all the treatments with half-life varying from 46 to 301 days. Thiamethoxam has a potential to leach down under heavy rainfall conditions.
Bron: S Gupta et al. Bull Environ Contam Toxicol (2008) 80: 431-437
http://www.springerlink.com/content/71x2x5h32466230r/fulltext.pdf
- Log in to post comments