Ecological footprint model of heavy metal pollution in water environment based on the potential ecological risk index

Social heavy metal pollution poses a significant threat to aquatic ecosystems. Heavy metals are easily adsorbed by sediments and have cumulative effects on aquatic organisms, which is different with the hypothesis of the conventional ecological footprint model that the pollutants are independently degraded by water bodies. To solve this problem, an ecological footprint for heavy metal pollution (EFHM) is constructed based on the potential ecological risk index (PERI). EFHM is defined as the sediment area to control the cumulative ecological risk of heavy metals within the allowable limit. And then, EFHM uses ecological footprint index (EFI) and ecological footprint contribution rate (EFCR) to quantify the hazard of social heavy metal load and recognize the key risk factor. EFHM is applied for assessing the heavy metal pollution of Central China. The results show that (i) the EFHM model can effectively evaluate the cumulative ecological hazards of heavy metals in sediment. (ii) The EFHM values of Central China in 2015 and 2020 are 20,764.56 and 17,358.59 km², respectively. (iii) Compared with 2015, the EFI values of Hunan Province and Jiangxi Province in 2020 decrease from 1.53 to 0.87 to 1.23 and 0.39, respectively, both of which are improved by one grade. The EFI values of Hubei Province increases from 0.42 to 1.34, which is deteriorated by one grade. (iv) In 2020, both of the key risk factors of Hunan Province and Hubei Province are Hg, and the crucial hazard source of Jiangxi Province is Cd. (v) The mine pollution control in Central China should be further consolidated, and the wastewater treatment of electronics and machinery industries should be strengthened.