Do long-term high nitrogen inputs change the composition of soil dissolved organic matter in a primary tropical forest?

Niu, Guoxiang1; Yin, Gege2; Mo, Xiaohan3; Mao, Qinggong1; Mo, Jiangming1; Wang, Junjian2; Lu, Xiankai1

2022-09-01

10.1088/1748-9326/ac8e87

Environmental Research Letters   Impact Factor & Quartile

1748-9326

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.

soil carbon sequestration nitrogen addition water-extractable organic matter FT-ICR MS tropical forest dissolved organic carbon

SCI

English

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National Natural Science Foundation of China["41922056","42192513","42122054"] ; Youth Innovation Promotion Association CAS[Y201965]

Environmental Sciences & Ecology ; Meteorology & Atmospheric Sciences

Environmental Sciences ; Meteorology & Atmospheric Sciences

WOS:000853751300001

IOP Publishing Ltd

Web of Science

1.Chinese Acad Sci, Key Lab Vegetat Restorat & Management Degraded Ec, South China Bot Garden, Guangzhou 510650, Peoples R China
2.Southern Univ Sci & Technol, Sch Environm Sci & Engn, State Environm Protect Key Lab Integrated Surface, Shenzhen 518055, Peoples R China
3.Peking Univ, Peking Univ Shenzhen Grad Sch, Sch Urban Planning & Design, Shenzhen 518055, Guangdong, Peoples R China

Niu, Guoxiang,Yin, Gege,Mo, Xiaohan,et al. Do long-term high nitrogen inputs change the composition of soil dissolved organic matter in a primary tropical forest?[J]. Environmental Research Letters,2022,17(9).

Niu, Guoxiang.,Yin, Gege.,Mo, Xiaohan.,Mao, Qinggong.,Mo, Jiangming.,...&Lu, Xiankai.(2022).Do long-term high nitrogen inputs change the composition of soil dissolved organic matter in a primary tropical forest?.Environmental Research Letters,17(9).

Niu, Guoxiang,et al."Do long-term high nitrogen inputs change the composition of soil dissolved organic matter in a primary tropical forest?".Environmental Research Letters 17.9(2022).