The Application of the Mathematical Model for Predicting the Threshold Concentrations of the Influence of Pesticides on the Sanitary Status of Waters

Abstract

Introduction. The rapid growth in the production and use of pesticides poses a real risk of the possible contamination of water bodies, which determines the urgency of the improving the methods of hygienic rating of pesticide preparations in water bodies, as well as the search for screening methods for establishing threshold concentrations.The issues of the need to improve the methodological approaches to the hygienic regulation of pesticide products in water of water bodies are considered, the need for further scientific study of this issue is shown. Material and methods. There are presented results of ourselves laboratory studies on the effect of herbicides of the sulfonylurea class on the processes of self-purification of reservoirs according to the Biological Oxygen Demand (BOD) index. In the work there were used substances of the sulfonylureas derivatives with a multi-directional mechanism of action that exerts both a stimulating and inhibitory effect on the course of processes of the biochemical oxygen consumption. With the use of the formula (Gotovtsev A.V., 2016), the total biochemical oxygen consumption for sulfonylurea derivatives was calculated from the two experimentally measured BOD values. Results. The data of biochemical oxygen consumption for two substances, obtained as a result of experimental studies, are presented. Selected substances have a multi-directional effect on the course of biochemical processes: stimulation - deviation of BOD from the control (%); inhibition - deviation of BOD from the control (%). There was made an estimation of the possible use of the formula for calculating the total biochemical oxygen consumption obtained in the solution of the modified Streeter-Phelps equation system for pesticides of the sulfonylurea class. The formula was applied as a mathematical model for the predictive assessment of the establishment of threshold concentrations of pesticides on the effect on the sanitary regime of water bodies (accordingly to BOD index). Discussion. In the paper, experimental and calculated values of biochemical oxygen consumption were compared, which shows the possibility of using this mathematical method for predicting the effect of pesticidal preparations of this class on the processes of self-purification of water reservoirs. Conclusion. There was shown the possibility of using mathematical modeling methods, in particular, the modified Streeter-Phelps system of equations in the practice of sanitary and hygienic investigations.