Discussion of an environmental depletion assessment method-A case study in Xinjiang, China

Environmental process assessment based on the environmental depletion index (EDI) is an important part of the long-term monitoring and early warning mechanism of China's resources and environmental carrying capacity. The EDI aims to realize the unified environmental impact assessment of economic and environmental systems through the ratio relationship between economic growth and pollutant emission growth. However, in terms of pollutant emissions, the EDI ignores the environmental capacity (EC), which means that the effectiveness and objectivity of environmental impact assessment must be verified. In this study, with Xinjiang as an example and based on the EDI, Sulfur dioxide (SO2), Nitrogen oxide (NOx), Chemical oxygen demand (COD) and Ammonia nitrogen (NH3-N) were selected for calculation and assessment both without and with consideration of EC and for discussion of the suitability of the environmental depletion method for resources and environmental carrying capacity. The results indicated that (1) the percentages of SO2, NOx, COD, NH3-N and C-EDI in counties and cities that tend to be poor and lack EC were 32.98%, 29.79%, 30.85%, 28.72% and 38.30%, respectively, while the percentages in counties and cities with EC were 10.64%, 3.19%, 13.83%, 8.51% and 10.64%, respectively. (2) When EC was included, the number of counties and cities where changes in SO2, NOx, COD, NH3-N and C-EDI tended to be "poor -> good" were 23, 26, 17, 21 and 28, respectively, and the number of counties and cities where such changes tended to be "good -> poor" were 2, 1, 1, 2 and 2, respectively. (3) EC inclusion corrected overestimated or underestimated EDI results, making the evaluation results more objective and reasonable. This understanding provides a scientific reference for the coordinated development of the regional economy and environment in Xinjiang and worldwide.