Fujian Key Laboratory of Coastal Pollution Prevention and Control, Xiamen University, Xiamen 361102, China; Institute of Oceanography, Minjiang University, Fuzhou 350108, China.
Fujian Key Laboratory of Coastal Pollution Prevention and Control, Xiamen University, Xiamen 361102, China.
Mar Pollut Bull. 2020 Mar;152:110884. doi: 10.1016/j.marpolbul.2020.110884. Epub 2020 Jan 25.
It remains challenging to identify nitrate sources in streams due to complications associated with anthropogenic inputs and in-stream biogeochemical processes. We used dual isotopic analysis of nitrate and a Bayesian isotope mixing model to explore the dynamics of nitrate sources and their associated transformations among three types of headwater watershed with different dominant land use types during four seasons in Jiulong River Watershed, a coastal China watershed. Nitrogen sources were the primary determinant of the δN-NO and seasonal differences in biogeochemical processes exhibited among watersheds. Nitrate was mostly derived from nitrification in spring and summer, whereas atmospheric deposition greatly influenced the isotopic composition in autumn and winter. Chemical fertilizer contributed the largest to the riverine nitrate, accounting for 36.9 ± 12.3%, followed by soil N (27.2 ± 4.4%), atmospheric deposition (23.9 ± 11.8%) and manure & sewage (12.0 ± 5.9%). This study reveals the seasonality of riverine nitrate sources under changing watershed land use patterns.
由于人为输入和河流内生物地球化学过程的复杂性，鉴定河流中的硝酸盐来源仍然具有挑战性。本研究采用硝酸盐双同位素分析和贝叶斯同位素混合模型，探讨了不同主导土地利用类型的三种类型的河源流域在四个季节中的硝酸盐来源动态及其相关转化。氮源是δN-NO 的主要决定因素，流域之间的生物地球化学过程也表现出季节性差异。硝酸盐主要来源于春夏季的硝化作用，而大气沉降在秋冬季极大地影响了同位素组成。化肥对河流水硝酸盐的贡献最大，占 36.9 ± 12.3%，其次是土壤 N（27.2 ± 4.4%）、大气沉降（23.9 ± 11.8%）和粪肥/污水（12.0 ± 5.9%）。本研究揭示了在变化的流域土地利用模式下，河流水硝酸盐来源的季节性。
