Impacts of trade-driven outsourced nitrogen emissions on environment and environmental inequities in China

Rapid growing interregional and interprovincial trade in energy, industrial products, and agricultural goods, mainly from Northern to Southern China, helps the social-economic development of the nation but potentially causes environment inequity. The latter is, however, less known. This study examines the trade-driven transfer of nitrogen emissions and simulates subsequent total atmospheric inorganic nitrogen (TIN) deposition in China for 2017, focusing on potential ecological impacts and environmental disparities resulting from interprovincial trade, particularly the north-south transfer of virtual nitrogen emissions. TIN depositions exceeding critical load, indicating adverse effects on ecosystems across China related to trade activities, are quantified. Findings reveal significant environmental inequity in outsourcing goods and services through trade, demonstrating that trade-driven TIN deposition has negatively impacted the ecosystem in Northern China. In 2017, the southern and eastern coastal provinces experienced the highest net outflows of atmospheric nitrogen pollutants, transferring 462.85 and 411.34 kilotons of NO_x and 230.95 and 349.49 kilotons of NH₃, respectively, to less developed provinces that export energy and agricultural products to these well-developed regions. Interprovincial trade reduced the total atmospheric TIN deposition by 0.03, 0.14, and 0.16 Tg N·yr⁻¹ in Beijing-Tianjin, the eastern coastal region, and the southern coastal region, respectively, through the procurement of goods and services. Our results also indicate that interprovincial trade exacerbated environmental inequities to Northern and Western China. Notably, Inner Mongolia experienced the most severe environmental inequity through its trade with other provinces in China, resulting in a 4.38 % increase in areas where TIN deposition exceeded the critical load.