Response relationships between carbon and nitrogen characteristics of coastal wetlands and socioeconomic development： a case study of Dongtai City， Jiangsu Province， China

Coastal wetland ecosystems are intrinsically linked to regional socioeconomic development. However， the internal response relationship between these two systems remains unclear. This study took Dongtai City as a study case and used systematic field sampling and multi-source data integration. Partial least squares structural equation modeling （PLS-SEM） was employed to analyze the coupled relationships among socioeconomic development， river surface water quality， and sediment carbon and nitrogen characteristics. The results indicated that over the past five years， both the socioeconomic level and urbanization rate of Dongtai City have increased steadily. Water quality exhibited significant seasonal fluctuations， while a marked declining trend in total nitrogen （TN） was observed. Meanwhile， total organic carbon （TOC） and TN contents in coastal wetland sediments showed minor fluctuations. The PLS-SEM analysis revealed that socioeconomic development indirectly regulated TOC and TN contents in coastal wetlands （path coefficient = 0.1， P P < 0.001）. This study elucidated the internal nexus between macro-socioeconomic drivers and micro-nutrient characteristics in coastal wetlands， providing a scientific foundation for the synergistic advancement of ecological conservation and the marine economy.