Atrazine concentrations

Wu et al. [388] carried out measurements of the enrichment of Atrazine on the micro surface water of an estuary. These authors used a micro surface water sampling technique with a 16 mesh stainless steel screen collecting bulk sampled from the top 100-150 pm of the surface. Atrazine concentration in the actual micro surface was estimated to vary in the range 150-8850 pg/1. 

Although annual use of atrazine in the United States is about 35 million kg (Alvord and Kadlec 1996 Carder and Hoagland 1998), atrazine concentrations in human foods are negligible. Monitoring of domestic and imported foods in the human diet by the U.S. Food and Drug Administration between 1978 and 1982 showed that only 3 of 4500 samples analyzed had detectable atrazine residues. Two samples in 1980 contained 0.01 and 0.08 mg atrazine/kg and one in 1978, following a known contamination incident, contained 47 mg/kg (Reed 1982). 

Table 11.2 (continued) Atrazine Concentrations in Selected Watersheds... 

Banded tilapia, Tilapia sparrmanii 310-6700 Sublethal effects after 72 h include decreased activity, color changes, coughing, and maximum blood atrazine concentrations of about 3 mg/L 20... 

Biomarkers of atrazine exposure is a developing field (Lu et al. 1998) that merits additional research. For example, concentrations of atrazine in saliva of rats was significantly correlated with rat free atrazine plasma concentrations. About 26% of the atrazine in rats is bound to plasma proteins (and is unavailable for transport from blood to saliva) and is independent of plasma levels of atrazine. Salivary concentrations of atrazine reflect total plasma free atrazine concentration — in the 50 to 250 pg/L range — which may be of toxicological significance (Lu et al. 1998). 

FIGURE 4.3 Exceedence curve for annual maximum atrazine concentrations in Tennessee pond water, based on exposure simulation using Monte Carlo analysis. 

FIGURE 4.5 Risk curves based on exposure distribution for annual maximum atrazine concentrations in Tennessee ponds and chronic species sensitivity distributions for aquatic plants and animals. 

Note that in Table E6.12.1, the concentrations at 1 hr and 1 day are above the initial atrazine concentration (1,000 g/m ). This is one problem with Dirac delta boundary conditions because they initially have no volume, only mass. At greater elapsed time, however, the inaccuracies of the Dirac delta solution have a minimal impact on the resulting concentration. 

Decreased oxygen production immediately on exposure significant recovery within 2 weeks despite constant atrazine concentrations (Cunningham etal. 1984)... 

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