Simulation of the persistence of atrazine in soil at different sites in Portugal

Abstract

Summary The effects of soil temperature and soil moisture content on the rates of degradation of atrazine, were measured in the laboratory in soils from different sites in Portugal. Persistence of atrazine was measured in the same soils in the field during the spring and summer of 1984, 1985, 1986 and 1987. Weather records from the different sites, measured during the periods of the field experi ments, were used in conjunction with appropriate constants derived from the laboratory data in a computer program to simulate persistence in the field. The model generally overestimated the ob served soil residues, particularly during the first 7–14 days after application. The fit from the model was good from day 14 to the end of the experiments.

Evaluation of soil temperature effect on herbicide leaching potential into groundwater in the Brazilian Cerrado

“…where T r ( ¼ 20 or 25°C) is the reference temperature, E a (kJ mol À1 ) is the pesticide degradation activation energy and R ¼ 8:314 Â 10 À3 kJ mol À1 K À1 is the gas constant (Keen and Spain, 1992;Rocha and Walker, 1995).…”

The Geochemistry of Pesticides

“…This dependence has been described through the use of an empirical equation, introduced by Walker (1974), that expresses transformation half-life as an inverse exponential function of soil moisture content (up to field capacity). The Walker equation has been used to quantify the effects of soil moisture on the rates of transformation of atrazine (Rocha and Walker, 1995), propyzamide, napropamide (Walker, 1974), and at least 25 other pesticide compounds (Gottesbü ren, 1991). Similarly, Parker and Doxtader (1983) found that the rate of transformation of 2,4-D in a sandy loam increased with decreasing soil moisture tension, but observed an exponential relation between the two variables that was different from that implied by the Walker equation.…”

“…In a comprehensive review of 178 studies that compared observed pesticide concentrations in soils with those predicted using a pesticide persistence model, Beulke et al (2000) demonstrated the importance of accounting for spatial and temporal variations in temperature and moisture in estimating the rates of pesticide transformation. Interactions between abiotic and biological factors are likely to be responsible for the observation that the nature of the relation between soil moisture and the rates of pesticide transformation may, in turn, depend upon soil texture (e.g., Gan et al, 1999;Rocha and Walker, 1995). Rocha and Walker (1995) also observed that the effect of temperature on atrazine transformation could be a function of soil texture, as well.…”

“…Interactions between abiotic and biological factors are likely to be responsible for the observation that the nature of the relation between soil moisture and the rates of pesticide transformation may, in turn, depend upon soil texture (e.g., Gan et al, 1999;Rocha and Walker, 1995). Rocha and Walker (1995) also observed that the effect of temperature on atrazine transformation could be a function of soil texture, as well. However, while the nonlinear regression model of Fenner et al (2007) for atrazine (mentioned earlier) included temperature, pH, sand content, organic carbon content, and two depthrelated parameters as explanatory variables, volumetric water content was not retained as a predictor variable in the final equation.…”

Sequential Remediation Processes for a Low Level Pesticide Wastewater

“…A number of mechanisms have been reported for the degradation process including mineralization, biotransformation, humificaiton and volatilization [20,[41][42][43]. Biodegradation is accelerated by high temperature, optimum moisture content and presence of sufficient organic matter [20,42,44].…”