溶解有机碳
环境化学
生物地球化学
化学
土壤碳
固碳
作文(语言)
总有机碳
氮气
有机质
沉积(地质)
土壤有机质
土壤水分
环境科学
土壤科学
沉积物
地质学
有机化学
古生物学
语言学
哲学
作者
Guoxiang Niu,Gege Yin,Xiaohan Mo,Qigui Mao,Jiangming Mo,Junjian Wang,Xiankai Lu
标识
DOI:10.1088/1748-9326/ac8e87
摘要
Abstract Dissolved organic matter (DOM) plays a key role in forest carbon biogeochemistry by linking soil organic carbon (SOC) sequestration and water fluxes, which is further shaped by elevated atmospheric nitrogen (N) deposition. Although enhanced SOC sequestration was evidenced in tropical forests due to rising N deposition, it remains unclear how long-term N inputs affect soil DOM composition, which regulates SOC sequestration capability due to its mobility and biological instability. Here, the quantity, optical properties, and molecular-level characteristics of soil DOM based on a simulative N deposition experiment with four N addition levels (0, 5, 10, and 15 g m −2 yr −1 ) were studied in a primary tropical forest in south China. Results showed that 18 year N additions significantly altered soil DOM composition, with an increasing trend in soil dissolved organic carbon content. Medium- (10 g m −2 yr −1 ) and high-N addition (15 g m −2 yr −1 ) markedly elevated DOM average molecular weight by 12% and aromaticity, with specific ultraviolet absorbance at 254 nm increasing by 17%, modified aromatic index by 35%, and condensed aromatics by 67%. Medium- and high-N addition also increased recalcitrant DOM components but decreased other DOM components, with increasing percentages of lignin-like, tannin-like, and carboxylic-rich alicyclic molecule-like compounds, and decreasing percentage of more bioavailable contributions with H/C ratio >1.5. Importantly, significant correlations of the SOC content of the heavy fraction with optical properties and with recalcitrant DOM components were observed. These findings suggest that long-term N additions may alter soil DOM composition in a way to benefit soil OC storage in the primary tropical forests. It merits focusing on the mechanisms to association of soil DOM dynamics with SOC sequestration.
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