Occurrence of cyanazine compounds in groundwater: Degradates more prevalent than the parent compound

A recently developed analytical method using liquid chromatography/mass spe ctrometry was used to investigate the occurrence of cyanazine and its degra dates cyanazine acid (CAC), cyanazine amide (CAM), deethylcyanazine (DEC), and deethylcyanazine acid (DCAC) in groundwater. This research represents s ome of the earliest data on the occurrence of cyanazine degradates in groun dwater. Although cyanazine was infrequently detected in the 64 wells across Iowa sampled in 1999, cyanazine degradates were commonly found during this study. The most frequently detected cyanazine compound was DCAC (32.8%) fo llowed by CAC (29.7%), CAM (17.2%), DEC (3.1%), and cyanazine (3.1%). The f requency of detection for cyanazine or one or more of its degradates (CYTOT ) was more than 12-fold over that of cyanazine alone (39.1% for CYTOT Versu s 3.1% for cyanazine). Of the total measured concentration of cyanazine, on ly 0.2% was derived from its parent compound-with DCAC (74.1%) and CAC (18. 4%) comprising 92.5% of this total. Thus, although DCAC and CAC had similar frequencies of detection, DCAC was generally present in higher concentrati ons. No concentrations of cyanazine compounds for this study exceeded water -quality criteria for the protection of human health. Only cyanazine, howev er, has such a criteria established. Nevertheless, because these cyanazine degradates are still chlorinated, they may have similar toxicity as their p arent compound-similar to what has been found with the chlorinated degradat es of atrazine. Thus, the results of this study documented that data on the degradates for cyanazine are critical for understanding its fate and trans port in the hydrologic system. Furthermore, the prevalence of the chlorinat ed degradates of cyanazine found in groundwater suggests that to accurately determine the overall effect on human health and the environment from cyan azine its degradates should also be considered. In addition, because CYTOT was found in 57.6% of the samples collected from alluvia[ aquifers, about 2 -5 times more frequently than the other major aquifer types (glacial drift, bedrock/karst, bedrock/nonkarst) under investigation, this finding has lon g-term implications for the occurrence of CYTOT in streams. It is anticipat ed that low-level concentrations of CYTOT will continue to be detected in s treams for years after the use of cyanazine has terminated (scheduled for t he year 2000 in the United States), primarily through its movement from gro undwater into streams during base-flow conditions.