Slimy microbes put pesticides on guard
Slimy microbes put pesticides on guard
PESTICIDE levels in water can be reduced by specialist microbial slimes, say scientists at the Scottish Agricultural College.
"Helpful microbes growing naturally as slime layers on the roots of marsh plants and on gravel help break down organic wastes in the water," explains Dr Rod McKinlay from the SAC crop science and technology department. Those could now be used to help remove pesticides from water.
"Unused, diluted pesticides are often disposed of by spraying onto an area of uncropped land or through a soakaway. The problem with both methods is the potential for run off into surface or ground waters. We need to develop suitable farm-centred methods to minimise the risk of such pollution," says Dr McKinlay.
Constructed wetlands such as reed beds are already being used by an increasing number of farmers to help clean up farm waste waters. Plants help filter out fine particles and the associated microbes help break down organic wastes, he says.
An initial SAC investigation to see if the same system can be used to remove pesticides from contaminated water found it took 32-53 days to reduce a known level of atrazine in water below detectable levels. But, as the system was repeatedly exposed to the pesticide, the clean-up accelerated.
"After the fifth application, no chemical was detectable after just seven days. Further research showed the decline was due to the increased presence of the microbes," says Dr McKinlay.
"We are now engaged in Scottish Office funded work to isolate the helpful microbes, with a view to the commercial development of microbial methods for pesticide detoxification.
Coupled with diagnostic kits to check residues, this development could lead to a complete on-farm pesticide detoxification package," says Dr McKinlay.n
PESTICIDE SLIME
• Microbes degrade pesticidesin water.
• Repeated use increases rateof reduction.
• Water cleaning package possible.