Spatial evaluation of groundwater quality based on toxicological indexes and their effects on ecology and human health

Abstract

Groundwater quality is affected by numerous uncertain factors, and the evaluation process is liable to randomness and fuzziness. In order to evaluate the groundwater quality effectively and know its potential risks to ecology and human health. Taking 87 wells and 174 groundwater samples during wet and dry seasons in Mihe-Weihe River Basin as the research object, samples were collected randomly in the field and sent to the laboratory for instrument testing. Four toxicological indexes (NO2−, NO3−, F−, As) were selected, and a multi-attribute decision-making model was proposed with three dimensions. First, a subjective method based on T-spherical fuzzy theory coupling with TOPSIS and an objective method based on rough set theory were adopted to calculate weights, both of which are recombined by game theory. On this basis, the single-index unascertained measurement function was adopted to classify water quality in two dimensions. Moreover, for the vertical direction, a model based on the VIKOR method was built. Consequently, a three-dimensional water quality index (TWQI) was used to assess the water quality level in three dimensions. The results show that the groundwater quality is classified as medium (classification Ⅲ) in the Mihe-Weihe River Basin, and samples with poor water quality (classification Ⅳ) are mainly distributed downstream of the Mihe River, with groundwater depth ranging from 0 to 15 m, near Laizhou Bay. Ecological and health risk assessment (EHRA) shows that the potential risks to ecology and human health are classified as high, with nitrates and nitrites being the major contributors. Moreover, the risk in the wet season is greater than that in the dry season. This highlights an urgent need to improve groundwater quality in the Mihe-Weihe River Basin, to reduce the potential risks to ecology and human health caused by groundwater pollution.