title: The effect of the herbicide diuron on soil microbial activity.
abstract: The inhibitory effect of the herbicide diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea] on microbial activity in red Latosol soil was followed using microcalorimetry. The activity of the micro-organisms in 1.50 g of soil sample was stimulated by addition of 6.0 mg of glucose and 6.0 mg of ammonium sulfate under 35% controlled humidity at 298.15 (+/- 0.02) K. This activity was determined by power-time curves that were recorded for increasing amounts of diuron, varying from zero to 333.33 micrograms g-1 soil. An increase in the amount of diuron in soil caused a decrease of the original thermal effect, to reach a null value above 333.33 micrograms g-1 of herbicide. The power-time curve showed that the lag-phase period and peak time increased with added herbicide. The decrease of the thermal effect evolved by micro-organisms and the increase of the lag-phase period are associated with the death of microbial populations caused by diuron, which strongly affects soil microbial communities.
authors.affiliation: Instituto de Química, Universidade Estadual de Campinas, Caixa Postal 6154, 13083-970 Campinas, São Paulo, Brazil.
authors.forename: A G
authors.initials: AG
authors.lastname: Prado
authors.forename: C
authors.initials: C
authors.lastname: Airoldi
mesh_terms: D000645:Ammonium Sulfate / Q000494:pharmacology; D002151:Calorimetry / Q000379:methods; D004237:Diuron / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D017753:Ecosystem; D005947:Glucose / Q000494:pharmacology; D006540:Herbicides / Q000494:pharmacology*; D012987:Soil / Q000032:analysis; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000494:pharmacology*
chemical_list: D006540:Herbicides; D012987:Soil; D012989:Soil Pollutants; D004237:Diuron; D005947:Glucose; D000645:Ammonium Sulfate