Effects of salinity changes on nitrogen fate in lakes and wetlands of arid regions

JIANG Xing-yu; HU Yang; SHAO Ke-qiang; TANG Xiang-ming; GAO Guang

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China Environmental Science ›› 2026, Vol. 46 ›› Issue (1) : 319-328.

Environmental Ecology

Effects of salinity changes on nitrogen fate in lakes and wetlands of arid regions

JIANG Xing-yu, HU Yang, SHAO Ke-qiang, TANG Xiang-ming, GAO Guang

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Abstract

To investigate the influence of changes in water salinity (composition and concentration) on key nitrate reduction processes in lake wetlands of arid regions, field surveys and salinity-controlled experiments were conducted in Bosten Lake and Xiangsi Lake wetlands located in the arid zone of northwestern China. Field surveys revealed that denitrification rates in Bosten Lake and the surrounding Xiangsi Lake wetland ranged from 7.2 to 131.4 μmol/(kg·h), and salinity was identified as a key environmental factor affecting denitrification. The rates of dissimilatory nitrate reduction to ammonium (DNRA) varied from 2.6 to 19.9 μmol/(kg·h), which were primarily influenced by the ratio of dissolved organic carbon to nitrate in the water. In the salinity-controlled experiments, increased salinity (0.2‰~6.6‰) significantly inhibited denitrification rates: with increasing sodium sulfate concentration, denitrification rates declined by 25.7% (Bosten Lake) and 21.0% (Xiangsi Lake), respectively; while increasing sodium chloride concentration led to respective decreases of 36.7% and 31.1% in the two wetlands. Changes in salinity also significantly impacted DNRA rates: DNRA rates first increased and then decreased with rising sodium sulfate concentration in both wetlands, whereas they decreased by 26.1% (Bosten Lake) and 27.8% (Xiangsi Lake) with increasing sodium chloride concentration. Increased salinity exerted a stronger inhibitory effect on denitrificationcompared to DNRA, resulting in an elevated proportion of DNRA in total dissimilatory nitrate reduction. Overall, increased salinity will elevate lake nitrogen concentrations by inhibiting denitrification, while enhancing nitrogen retention potential by increasing the proportion of DNRA, thereby exacerbating the risk of nitrogen pollution in these lakes.

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denitrification / dissimilatory nitrate reduction to ammonium (DNRA) / Lake Bosten / sulfate / nitrogen pollution

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JIANG Xing-yu, HU Yang, SHAO Ke-qiang, TANG Xiang-ming, GAO Guang. Effects of salinity changes on nitrogen fate in lakes and wetlands of arid regions[J]. China Environmental Science. 2026, 46(1): 319-328

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