Atrazine persistence and toxicity in two irrigated soils of Australia

Abstract

The persistence of atrazine in two contrasting irrigated soils from the Riverine Plain of south-eastern Australia was measured in the laboratory at three constant temperatures. Particularly at lower temperatures atrazine was more persistent, by an order of magnitude, than reported for soils overseas; but in two successive field experiments, encompassing both surface and incorporated applications of atrazine in the heavier soil, residues measured after about 7 months were within the range expected from the literature. The measured residues were 2-6 times smaller than predicted using a simulation model, probably reflecting volatilization and other losses which are not included in the model, but which are expected to be substantial at the extremely high soil surface temperatures observed in the field. Comparative measurements of aged residues in the heavy clay soil showed higher results from chemical analysis of acetonitrile-water soil extracts than by in situ glasshouse bioassay using oats and turnips, demonstrating that only one third of the extractable residue was available to crops. Comparison of soil-based and hydroponic assay using soybeans showed that this soil reduced the effective atrazine concentration in solution by at least 16-fold, but sensitive crops could still be damaged when grown in rotation after tolerant crops, or if irrigated with contaminated water.

Effects of Spherosomes on Degradation of Pretilachlor and Esprocarb in Soil

“…Environmental factors can greatly influence the degradation rate of chemical compounds in soil, the most important being moisture, pH, organic carbon content, and pesticide formulation. Garcia-Valcarcel and Tadeo 9) reported that degradation rates increased with soil moisture content for hexazinone and simazine, which is in agreement with the results of Walker and Blacklow 10) for atrazine and simazine and those of Bowmer 11) for atrazine; therefore, we maintained constant soil moisture. Pfaender and Alexander 12) reported that the numbers of microorganisms potentially able to cometabolize Dichloro Diphenyl Trichloro ethane (DDT) were high in raw sewage as a result of the addition of glucose and diphenylmethane.…”

Atrazine Transport in Irrigated Heavy- and Coarse-Textured Soils, Part I: Field Studies

“…However, in a non-irrigated alluvial soil Persicani et al (1996) reported that almost 60% of the atrazine remained in the soil 1 month after application. As reported by Bowmer (1991), the convective movement of evaporating water is expected to increase the accumulation of herbicides at the soil surface, and to enhance the volatilization of the compounds. Other processes that can contribute to the rapid degradation of surface-applied chemicals include photochemical degradation.…”

“…Volatilization of atrazine might have played an important role for this rapid decrease of atrazine in the soil because no irrigation or rain occurred during this initial period. Kearney et al (1964) (cited by Bowmer, 1991) reported substantial volatilization from most soil surfaces, up to 35% loss occurring in 72 h at 353C. Also, Tasli et al (1996) indicated that volatilization reached 15% of the a.i.…”

“…Considering the pooled data for both years in the entire (1996 and 1997) soil pro"le (0}60 cm depth) the measured half-life, according to a "rst-order rate equation was 23 days. In a study conducted in a heavy soil (60% clay), under irrigated conditions (furrow irrigation), Bowmer (1991) reported that more than 50% of the atrazine residues disappeared in 11 days. However, in a non-irrigated alluvial soil Persicani et al (1996) reported that almost 60% of the atrazine remained in the soil 1 month after application.…”

Properties of an aged phenanthrene-contaminated soil and its response to bioremediation processes

“…This sequestration results in a reduced bioavailability of contaminants to bacteria (Nam et al 1998) and higher organisms such as plants (Bowmer 1991). From a microbial perspective, soils containing an aged contamination can be considered oligotrophic (Wick et al 2003) and harsh environments for microbes to proliferate.…”