Spatio-temporal variation of groundwater contamination using IEA-UEF in urban areas of Jilin City, North-eastern China

Groundwater monitoring wells located in urban areas of Jilin City were sampled from 1980 to 2009 for eight groundwater quality parameters: pH, SO₄²⁻, Cl⁻, NO₃⁻-N, NO₂⁻ -N, NH₄⁺-N, F⁻, and total hardness (TH). The data were analysed by a universal exponential formula based on an immune evolutionary algorithm, and later mapped with the Kriging interpolation method. The primary objectives were to assess the main parameters that influenced groundwater quality and the spatio-temporal variability of groundwater contamination over several years. The results showed that NO₃⁻, NH₄⁺, and TH were the main parameters that influenced groundwater quality. Spatially, groundwater was polluted in all urban areas to varying degrees, and the Jiangbei district was the most heavily polluted location. Temporally, the groundwater contamination status could generally be classified into four stages and showed the following pattern during 1980–2009: heavy – light – heavy – light.