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ARS Home » Southeast Area » Oxford, Mississippi » National Sedimentation Laboratory » Water Quality and Ecology Research » Research » Publications at this Location » Publication #152126

Title: ATRAZINE IN WATER AND BIODEGRADATION IN A RECHARGE AREA OF GUARANY AQUIFER IN BRAZIL

Author
item CERDEIRA, ANTONIO - BRAZILIAN MINISTRY OF AGR
item SANTOS, N - SAO PAULO UNIVERSITY
item PESSOA, M - BRAZILIAN MINISTRY OF AGR
item Smith Jr, Sammie
item LANCHOTE, V - SAO PAULO UNIVERSITY

Submitted to: Bulletin of Environmental Contamination and Toxicology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/21/2004
Publication Date: 7/1/2004
Citation: Cerdeira, A.L., Santos, N.A., Pessoa, M.C., Smith Jr., S., Lanchote, V.L. 2004. Atrazine in water and biodegradation in a recharge area of Guarany Aquifer in Brazil. Bulletin of Environmental Contamination and Toxicology. 73:117-124.

Interpretive Summary: The region of Ribeirão Preto city located in São Paulo State, Southeastern Brazil, is an important sugarcane producing area. This region is also an important recharge area for the groundwater supply of the Guarani aquifer, the source of drinking water supply of the city and region. Intensive cultivation in this area has demanded the constant and sometimes abusive use of fertilizers and pre-emergent herbicides. The risk of groundwater contamination by those chemicals, which are normally applied annually, has been a major concern. Due to the high permeability of some soils in this region, the high mobility of the herbicides and fertilizers applied, and the fact that the area is a recharge area, it is important to investigate the potential transport of the applied herbicides to the underlying aquifer. The cultivation of sugarcane in this area demands the constant use of the herbicide atrazine to control broadleaf and grassy weeds. Recent law from the Brazilian Health Ministry has set the maximum concentrations in drinking water to 2.0 ug/L (ppb) of atrazine. Although there has been some research on groundwater contamination with atrazine in Brazil, none of the studies have been conducted to determine the precise concentrations present in this aquifer. Atrazine has shown no potential to reach groundwater when evaluated by simulation models. This result agrees with the information obtained by means of monitoring wells located in the study area, where that atrazine was not detected in the groundwater. Laboratory biodegradation studies have also shown the presence of microorganisms capable of degrading atrazine.

Technical Abstract: This paper reports research has been conducted to determine atrazine concentrations in the Guarany Aquifer as well as atrazine biodegradation in soils of the area. The results obtained with the microbial populations present in the soil samples incubated in the laboratory with atrazine have shown the presence of atrazine biodegraders. The initial incubation of soil samples with atrazine is not a decisive factor on the selection of metabolizing strains. The assay conditions to demonstrate the disappearance of the atrazine from the minimal or even rich medium are highly relevant. It can be concluded that microbial species involved in the biodegradation are different, not necessarily demanding the presence of a nitrogen source. The detection of the presence of atrazine biodegrading microorganisms may explain the absence atrazine residues in groundwater at the edge of the watershed as shown in the laboratory residue analysis and in the simulation model.