Acetochlor sorption and degradation in limestone subsurface and aquifers     

Gry S Janniche  Christophe Mouvet  Hans‐Jørgen Albrechtsen 《Pest management science》2010,66(12):1287-1297

BACKGROUND: Acetochlor, introduced on the market in 1994, is used extensively worldwide, but sorption and degradation studies, including subsurface, are scarce, and there appear to be no such studies with aquifer sediment according to the present mini‐review. Sorption, degradation and mineralisation of acetochlor were investigated in heterogeneous limestone down to 43 m below surface (mbs) in four European aquifers (1.7–59 mbs), both aerobic and anaerobic. RESULTS: Sorption revealed K_d values of 3.39–4.96 L kg^?1 in topsoil, < 0.01–2.02 L kg^?1 in heterogeneous limestone, 0.06–0.72 L kg^?1 in aerobic aquifers and 1.03–4.60 L kg^?1 in microaerobic or anaerobic aquifers. The mineralisation half‐lives in the samples from 0.0–0.6 mbs were 0.8–2.1 years and 4.7–95 years in the unsaturated limestone samples from 1–43 mbs. Out of 22 samples from four different European aquifers, acetochlor was mineralised in five samples (half‐lives of 9–19 years), all from the same aquifer and core section (19.25–19.53 mbs). CONCLUSION: Sorption was weak in limestone and aerobic sandy aquifers, and strong in topsoils and in reduced sandy aquifers. Redox conditions controlled the extent of acetochlor sorption in aquifers, as reduced conditions induced increased sorption. Acetochlor was mineralised in deep subsurface, though slowly, and, as mineralisation is the only true removal mechanism in natural attenuation, even slow mineralisation in aquifers with long residence times can have a significant impact. Copyright © 2010 Society of Chemical Industry  相似文献   

An abattoir-based case-control study of risk factors for mycobacteriosis in Norwegian swine     

Staal Alfredsen  Eystein Skjerve 《Preventive veterinary medicine》1993,15(4):253-259

An outbreak of mycobacteriosis in swine herds in southwestern Norway from autumn 1986 to 1990 is described. The prevalence of generalised infection in the pigs was higher than usual during the outbreak resulting in the condemnation of 0.3% of the swine carcasses in 1987. A case-control study involving 35 herds (17 herds with more than two tuberculous pigs at slaughter and 18 herds with no evidence of infection at slaughter) showed that an increased risk of infection was linked to combined production with sows and slaughter pigs in the same herd. The presence of birds in the pig house was another contributing risk factor. The standard of the ventilation system, covering of the feed tank, cleaning of the house less frequently than once a year and use of litter were not associated with tuberculous lesions.  相似文献