Risk assessment and optimization of domestic waste treatment in the Qinghai-Tibet Plateau ecological barrier zone: A case study of Qinghai Province

Abstract

Qinghai-Tibet Plateau is a significantly ecological security barrier in China and even Asia. However, the improper treatment of domestic waste has become a prominent threat to the ecological security of Qinghai-Tibet Plateau ecological barrier zone. Hence, the scientific risk assessment and management strategies for domestic waste treatment in urban and rural settlements are fundamental to improving the living environment and stability of the ecological barrier zone. Based on the quantitative measurement of the generation and treatment level of domestic waste in 4306 settlements of Qinghai Province, this study constructed a framework of eco-environmental risk assessment by considering the hazard, vulnerability, and exposure factors, from the perspective of the whole process of the collection, transportation, and disposal of domestic waste treatment system. The TOPSIS and obstacle degree model were applied to comprehensively assess the eco-environmental risk and control obstacles of waste treatment. The results show that the distribution of domestic waste was characterized by an overall pattern of "globally dispersed, locally agglomerated" in Qinghai Province, and the rate of the centralized domestic waste treatment was relatively low at 62.33%. The eco-environmental risk of domestic waste treatment in Qinghai Province was at a medium risk level in general, with 36.90% of the settlements at an upper medium or high level. Furthermore, the eco-environmental risk showed a pattern of increase from the valley of the Yellow River and Huangshui River to the Qaidam Basin, the Qinghai Lake region, the Qilian Mountains region, and the highland alpine in southern Qinghai. Moreover, the eco-environmental risk of waste transportation was the highest in the domestic waste treatment system, with the Qilian Mountains, the eastern section of the Kunlun Mountains, and the valley of the highland alpine in southern Qinghai being notable. The analysis of obstacle degrees indicated that the alpine natural environment and the lag in decentralized waste disposal technology were main obstacles to risk control in Qinghai Province. Aiming at the complete disposal of domestic waste and near-zero stress to the eco-environment in the Qinghai-Tibet Plateau ecological barrier zone, greater efforts are needed to bridge the gap between hardware and software infrastructures for domestic waste management, carry out the policy of giving rewards and subsidies for effective waste treatment, and reinforce the environmental ethics education for urban residents, farmers, and herdsmen. Taking into account the eco-environmental risk of the whole process of the domestic waste treatment system, it is wise to adjust the basic unit of the domestic waste treatment system from the county scale to the town scale and implement three models of treatment:urban-rural integration treatment, centralized treatment in the town, and decentralized treatment in the villages based on the dispersion of urban and rural settlements and domestic waste generation on Qinghai-Tibet Plateau.