水生态学杂志2025，Vol.46Issue(5)：1-9,9.DOI:10.15928/j.1674-3075.202506270005
中国近海溶解无机氮遥感监测及时空变化研究
Satellite-based Estimation of Spatiotemporal Variation of Dissolved Inorganic Nitrogen in the Coastal Waters of China
摘要
Abstract
Dissolved inorganic nitrogen(DIN)is a crucial nutrient source for marine primary production and plays a significant role in regulating biological geochemical processes in marine ecosystems.Howev-er,driven by climate change and anthropogenic activities such as rapid urbanization and industrialization,DIN concentrations in coastal waters of China have exhibited pronounced changes in spatiotemporal dis-tribution.Therefore,systematically identifying the spatiotemporal variation and influencing factors of DIN is crucial for health assessment and scientific management of coastal ecosystems.In this study,a DIN concentration inversion model suitable for China's coastal waters was developed by integrating satel-lite remote sensing imagery with machine learning algorithms.The parameters of the random forest(RF)model were optimized using Recursive Feature Elimination(RFE)and Grid Search with Cross-Validation(GridSearchCV)to improve model performance.Based on the optimized model,we estimated DIN con-centrations in typical coastal areas within 50 nautical miles of the shorelines of the Bohai Sea,Yellow Sea,East China Sea,and South China Sea using MODIS image data during the period 2003-2021.Additional-ly,the Spearman rank correlation coefficient was used to assess the correlation between DIN concentra-tion and human activities.On the test set,the coefficient of determination(R2)of the model was as high as 0.836,with a mean absolute error(MAE)of 0.047 mg/L.From 2003 to 2021,DIN in the coastal waters of China presented significant spatial heterogeneity,with higher concentrations observed nearshore and in semi-enclosed bays.During this period,the average annual DIN concentration in the coastal water of Bo-hai Sea was highest(0.315±0.045)mg/L,and with greater annual fluctuations than the East China Sea(0.200±0.006)mg/L and Yellow Sea(0.193±0.007)mg/L.The annual average DIN concentration in the South China Sea was the lowest and most stable(0.118±0.017)mg/L.DIN concentrations presented pro-nounced seasonal variations,with the highest levels observed in winter(0.221±0.007)mg/L and the low-est in summer(0.155±0.005)mg/L,and followed a unimodal annual pattern,initially decreasing and then increasing.The impacts of human activities on DIN concentration varied across regions:DIN concentra-tions were positively correlated with wastewater discharge and GDP in East China;In South China,DIN concentrations were influenced by agricultural expansion and urban pollution;In North China,DIN con-centrations exhibited a negative correlation with GDP and marine aquaculture;while in Northeast China,no significant correlation was observed between DIN concentrations and human activities.This study pro-vides an effective technical path for remotely sensing DIN concentration in China's coastal seas,and a sci-entific basis for evaluating and managing coastal water quality.关键词
溶解无机氮/机器学习/遥感反演/中国近海/时空动态Key words
dissolved inorganic nitrogen/machine learning/remote sensing inversion/coastal waters of China/spatial and temporal dynamics分类
资源环境引用本文复制引用
张昕玥,徐志豪,范文杰,陈凯恒,杨志峰..中国近海溶解无机氮遥感监测及时空变化研究[J].水生态学杂志,2025,46(5):1-9,9.基金项目
国家自然科学基金重点项目(52239005). （52239005）
