Aggregate risk of reactive nitrogen under anthropogenic disturbance in the Pearl River Delta urban agglomeration

Abstract

Social production and consumption in highly urbanized agglomerations dramatically aggravate the creation of reactive nitrogen (Nr). Excess Nr increases the aggregate risk of air and water quality deterioration, biodiversity loss and human health impairment. The aim of this study is to assess the aggregate risk of Nr under anthropogenic disturbance based on an exposure-effect model reconciling the Nr behavior in urban environment and corresponding integrated damage impacts. In a case study of Pearl River Delta (PRD) urban agglomeration, the Nr creation and distribution were quantitatively estimated in different subsystems. The various ecosystem service and human benefit losses related to Nr accumulation pressure were classified and quantified though damage costs obtained from literature. The results showed that anthropogenic disturbance dramatically changed the Nr creation and accumulation in this urban agglomeration compared with the average level for all of China. Anthropogenic Nr creation in the PRD urban agglomeration was 355.70 Gg, and total Nr accumulation in all subsystems was 607.05 Gg in 2010. With high industrialization and urbanization, Nr tended to flow into the atmosphere and water to generate risk rather than into the land. The damage impacts of Nr in the PRD urban agglomeration centered on human health impairment (40.97%), fuel and fiber production loss (23.55%), climate and air quality decline (22.41%). To harmonize the relationship between risk management and human economic drivers, sustainable human activity changes in vehicle use, denitrification engineering and nitrogen use efficiency are suggested.