The phosphorus release pathways and their mechanisms driven by organic carbon and nitrogen in sediments of eutrophic shallow lakes

Hui Li; Chun-Lei Song; Xiu-Yun Cao; Yi-Yong Zhou

doi:10.1016/j.scitotenv.2016.07.221

The phosphorus release pathways and their mechanisms driven by organic carbon and nitrogen in sediments of eutrophic shallow lakes

Sci Total Environ. 2016 Dec 1:572:280-288. doi: 10.1016/j.scitotenv.2016.07.221. Epub 2016 Aug 6.

Authors

Hui Li¹, Chun-Lei Song², Xiu-Yun Cao³, Yi-Yong Zhou³

Affiliations

¹ College of Biology and A&F Engineering, Tong Ren University, Tong Ren, Guizhou Province 554300, China.
² State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, 7# Donghu South Road, Wuhan 430072, China. Electronic address: clsong@ihb.ac.cn.
³ State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, 7# Donghu South Road, Wuhan 430072, China.

PMID: 27501427
DOI: 10.1016/j.scitotenv.2016.07.221

Abstract

To reveal phosphorus (P) release pathways from sediment and their mechanisms induced by organic matter enrichment, 116 sampling sites (including surface water and sediment) in 29 shallow lakes with different eutrophic degrees in Wuhan city, China, were investigated from July 2011 to November 2011. Empirical relationship and structural equation model indicated that the decomposition of total organic matter (TOM), including proteins (PRT), carbo-hydrates (CHO) and lipids (especially PRT) mediated by extracellular enzymes, accelerated the formation of anaerobic status. On the other hand, coupled nitrification-denitrification caused by ammonium (NH₄⁺-N) accumulation due to PRT decomposition further aggravated anaerobic status and nitrate removal in terms of the increase of dehydrogenase activity (DHA). As a consequence, ferric iron was reduced to ferrous iron and soluble reactive phosphorus (SRP) was released from iron-bound phosphorus (Fe(OOH)~P) in sediments. In addition, extracellular alkaline phosphatase can be induced by organic carbon and nitrogen on condition that the input of nitrogen (N) and carbon (C) exceeded by far that of P. Taken together, enrichment of N and C can result in P release through the formation of anaerobic status and alkaline phosphatase production. Hence, we indicated that a close coupling existed among C, N and P cycles.

Keywords: Eutrophic shallow lakes; Extracellular enzymes; Organic matter; Phosphorus release; Sediment.