Some aspects of the persistence and fate of acrolein herbicide in water

Abstract

Experimental data for the decay of acrolein approximated first order kinetics. The reaction continued to completion in local waters but in buffered solution (pH 5.1-8.6) an equilibrium was reached after reaction of about 92% of the acrolein. It is proposed that data presented on the effects of pH on decay of acrolein may be used as a conservative estimate of dissipation rates in water where non-target organisms are at risk. In flowing water in two channels the 8 to 10 fold discrepancy between observed and predicted rates of dissipation was attributed to major losses in volatilization and adsorption. A relatively non-volatile reaction product (which gave a positive reaction with dinitrophenylhydrazine) accumulated initially but dissipated rapidly, probably by microbiological processes, when acrolein concentrations fell below about 2 to 3 ppm.

Effect of Magnacide ® H Herbicide Residuals on Water Quality Within Wildlife Refuges of the Klamath Basin, CA

“…In other field experiments, the kinetics and half-life of acrolein concentrations in irrigation canals were similar to those observed in this study (O'Loughlin and Bowmer, 1975;Bowmer and Higgins, 1976;Bowmer and Sainty, 1977). The mean first order rate constant from eight canals was 0.163 hr -1 (SD = ±0.039) and varied between 0.104 and 0.211 hr -1 at pH 7.1 to 7.5 and water temperatures of 16 -24°C (Bowmer and Sainty, 1977).…”

“…The mean value corresponds to a half-life of 4.25 (SD = ±1.18) hours at a mean temperature of 21°C (SD = ±2.62). Similar kinetics for acrolein degradation have been shown previously in the laboratory where it was also demonstrated that the rate constants are independent of the initial acrolein concentrations but increase with decreasing pH (hydration) and increasing pH (condensation) (Pressman and Lucas, 1942;Hall and Stern, 1950;Bowmer and Higgins, 1976). The half-life of 46 hours (0.015 hr -1 ) calculated using dilute buffered solutions of acrolein in distilled water at 21 °C and pH 7.0 is considerably longer than the half-life observed in this and other field experiments.…”

“…In laboratory experiments, however, the half-life is influenced by the presence of the acrolein reaction products. Equilibrium is reached with 8 % of the original acrolein and 85 % of total aldehydes still present, but these do not persist in environmental waters where other methods of dissipation exist (Bowmer et al, 1974;Bowmer and Higgins, 1976). The results of field studies do not indicate such an equilibrium and are more consistent than the laboratory data with the results of bioassays with bacteria and fish which show the loss of biocidal activity of aged acrolein solutions after approximately 120 to 180 hours at a pH of 7.0 (Kissel et al, 1978).…”

“…It has been demonstrated that acrolein would be readily degraded by mixed microbial populations (Stover and Kincannon, 1983) while others have indicated that its toxicity to microorganisms may prevent biodegradation (Chou et al, 1978;Bridie et al, 1979). It has been suggested (Bowmer and Higgins, 1976) that the fall in pH observed during the decline of the acrolein reaction product in laboratory experiments is indicative of the formation of a carboxylic acid which is also produced during the microbial oxidation of aldehydes (Meikle, 1972).…”

“…The available data indicates that when acrolein is applied to agricultural canals at the recommended concentration, its presence is transient with a dissipation half-life of approximately 7.0 hours (O'Loughlin and Bowmer, 1975;Bowmer and Higgins, 1976;Bowmer and Sainty, 1977). During the summer irrigation months, Magnacide ® H is used routinely in the agricultural canals of the Tulelake Irrigation District (TID), California.…”