Modeling of convective-diffusion substance transfer and proposals as for development of an automatic system for monitoring and prevention of pollution of groundwater

Abstract

At the enterprise being studied, due to losses, compounds of chromium accumulated on the soil floor of the workshop and gradually migrated in the zone of aeration of groundwater (aquifer). The level of groundwater in the area of the electric workshop is in the depth of around 10 m (as measured by the Pravoberezhna Expedition), that is, the ways of migration of chromium compounds in the area of aeration was about 10 m). The aquifer layer is located in flood-fed glacial deposits represented by sands of heter-ogenous grains. The sands are overlayed by loamy sand and loam with inclusion of gravel of basement crystalline rock. The filtration coefficient of sands varies from 1 m to 5 m per day, and of loams, from 0.1 m to 1 m per day. For this reason, the loam can only cautiously considered as low-permeable soil overlaying the aquafer. Therefore, it was more sound to consider a scheme of two-layer aquifer, in which the upper layer (loam) is about 1.5-m-thick, and the thickness of the lower layer (sand) is 5 to 15 m. Hexavalent chromium pollution using a model of convective-diffusive flow in an aquifer at a given research location was studied. The flow was defined as linear. The model is formu-lated as a differential equation and comprises the following variables: (C) – concentration of chromium compounds; (t) – time of observation; (Д) – coefficient of filtering (convective) dif-fusion; (Vn) – actual speed of filtration of the flow; (V) – existing speed of filtration of the flow; (na ) – active porosity of the soils forming the aquifer; (K) – filtering coefficient of the aquifer; (I) – hydraulic slope of the flow in the natural environment. Real input data and values of variables were used. Function С (х, t) was calculated and plotted, with its envelope curves determining the maximum concentration of the substance. Proposals are given as for development of an automated monitoring system and avoid-ance of the pollutant.