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Nitrogen Fixation Occurring in Sediments: Contribution to the Nitrogen Budget of Lake Taihu, China
Author(s) -
Yao Xiaolong,
Zhang Lu,
Zhang Yunlin,
Zhang Bo,
Zhao Zhonghua,
Zhang Yibo,
Li Min,
Jiang Xingyu
Publication year - 2018
Publication title -
journal of geophysical research: biogeosciences
Language(s) - English
Resource type - Journals
eISSN - 2169-8961
pISSN - 2169-8953
DOI - 10.1029/2018jg004466
Subject(s) - bay , sediment , nitrogen fixation , benthic zone , environmental science , nitrogen , denitrification , fixation (population genetics) , hydrology (agriculture) , environmental chemistry , geology , oceanography , biology , chemistry , geomorphology , geotechnical engineering , organic chemistry , biochemistry , gene
Nitrogen fixation (N 2 fixation) in benthic sediment contributes a certain amount of bioavailable nitrogen (N) to aquatic systems. However, data on sediment N 2 fixation have been poorly documented and the contribution of sediment N 2 fixation to the N budget in lakes has rarely been studied. In this study, N 2 fixation rates in sediments of Lake Taihu were measured periodically using the traditional acetylene reduction assay. Results showed that the highest sediment N 2 fixation rate occurred in winter in Meiliang Bay, with a value of 258 nmol N·kg −1 ·hr −1 , and the lowest rates occurred in all seasons at some sites, with values near zero. East Taihu Bay, Meiliang Bay, the southwestern coastal area, and Zhushan Bay were found to be hotspots for sediment N 2 fixation activity. The annual N 2 fixation rate and volume in sediments of Lake Taihu were 0.083 g N·m −2 ·year −1 and 195 t N, respectively. The N inputs via fixation were much lower than those from river inflow, sediment release, and atmospheric deposition. This study reveals that N 2 fixation in sediments contributes only a minor part to the overall N budget, while it compensates for about 1.8% of sediment N 2 loss via denitrification. The minor contribution of sediment N 2 fixation to the overall N budget in Lake Taihu may be closely linked to sediment characteristics.