PAL and at times, the ES. Deethylatrazine appeared to be the most mobile compound.
It was detected sooner, showed up in more samples, stayed around longer and was at
higher concentrations than parent atrazine. The other 2 metabolites (diamino and
deisopropylatrazine) were not detected until at least 3 years after initial application of
atrazine. However these 2 metabolites are also breakdown products of 2 other
frequently used triazine herbicides, namely Cyanazine (Bladex) and Simazine (Pricep).
The State Lab of Hygiene does not differentiate the source of these metabolites. This
potentially affects the results of this study as these herbidices were used on the study site
in 1993 and 1995. This suggests that the concentrations of diamino and
deisopropylatrazine may not be attibuted to atrazine alone. However approximately 1.5
years after the initial application of atrazine, 4 of the 6 wells exceeded the ES. This
occurred prior to the application of the other triazine products.
Four years after the last application of atrazine (but which also includes the
applications from cyanazine (Bladex) and simazine (Princep)) total atrazine
concentrations (parent atrazine plus 3 metabolites) were over 2 ppb in 4 of the 6 wells
(wells 1, 3, 4, and 5). Only one well (well 6) had no detectable level of parent atrazine
or any metabolites. There seems to be a relationship to application, rates"of atrazine
over time however this may be questionable if the use of these other triazine products
affect the metabolite concentrations. Regardless of use of other triazine products, this
study does suggests that atrazine stays in the soil and is released slowly over time. How
long it stays and is available for leaching has yet to be determined.