Wind induced algal migration manipulates sediment denitrification N-loss patterns in shallow Taihu Lake, China. (1st February 2022)

• Record Type: Journal Article
• Authors: Shi, Wenqing; Zhu, Lin; Van Dam, Bryce; Smyth, Ashley R.; Deng, Jianming; Zhou, Jian; Pan, Gang; Yi, Qitao; Yu, Jianghua; Qin, Boqiang
• Is Part Of: Water research. Volume 209(2022)
• Publication Date: 2022-02-01
• Subjects: Denitrification -- Algal migration -- Nitrogen loss -- Sediment -- Shallow lake; Water -- Pollution -- Research -- Periodicals; 363.7394
• DOI: 10.1016/j.watres.2021.117887
• Languages: English
• ISSNs: 0043-1354

Abstract

Highlights: Algal migration in water column manipulates DNF in bed sediments. DNF rate is low but positively correlated with C hl-a in algae left zone. DNF rate is high but negatively correlated with C hl-a in algae concentrated zone. Abstract: Driven by winds, the distribution of algae is often noticeably patchy at kilometer scales in shallow lakes. The decomposition of the settled algal biomass may affect nitrogen (N) biogeochemical cycles and thereby N loss in sediments. In this study, we investigated sediment denitrification N-loss patterns along algal migration pathway in Taihu Lake, a shallow and eutrophic lake in China, and found that wind-induced algal migration in the overlying water manipulated the temporal and spatial patterns of denitrification N-loss in sediments. A N loss hotspot in sediments was created in the algae concentrated zone, where N loss was, however, temporarily inhibited during algal bloom seasons and generally exhibited a negative relationship with algal biomass. In the zone where algae have left, sediment N loss rate was relatively low and positively correlated with algal biomass. The decay of algal biomass generated organic carbon and created anoxia, favoring denitrification, while excessive algal biomass could deplete oxygen and inhibit nitrification, causing nitrate limitation for denitrification. Piecewise linear regression analysis indicated that algal biomass of Chl-a > 73.0 μg/L in the overlying water could inhibit denitrification N-loss in sediments. This study adds to our understanding of N biogeochemical cycles in shallow eutrophic lakes. Graphical abstract: Image, graphical abstract