黄河口、长江口及其邻近海域水体荧光溶解有机物特征与来源解析OA

Fluorescent dissolved organic matter(FDOM)indices,sources,and their relationships with nutrients in the Yellow River Estuary,the Changjiang River Estuary and their adjacent seas in July 2024 were investigated through field sampling and laboratory analysis.The fluorescence index ranged from 2.71 to 4.45 in the Yellow River Estuary and its adjacent sea and from 3.22 to 5.69 in the Changjiang River Estuary and its adjacent sea.The biological index values were 1.75～3.48 and 1.49～4.81,respectively,indicating that autochthonous sources contributed most to the organic matter.The humification index of the Yellow River Estuary,the Changjiang River Estuary and their adjacent seas ranged from 0.22 to 0.85 and 0.10 to 1.14,respectively,suggesting weak humification and strong autogenic processes.Spatially,the fluorescence index and biological index increased while the humification index decreased toward the sea,indicating that organic matter is primarily driven by autochthonous production with minimal humification.The FDOM and fluorescence index were significantly higher in the Changjiang River Estuary than in the Yellow River Estuary,suggesting greater concentrations of organic matter and more substantial autochthonous sources in the Changjiang River Estuary and its adjacent sea.The fluorescence index and biological index were significantly negatively correlated with nutrient concentrations,while the humification index was positively correlated with nutrients.These results indicate that nutrient inputs significantly influence FDOM,further altering the organic matter composition and water quality in estuaries.