Seasonal variation in release characteristics and mechanisms of sediment phosphorus to the overlying water in a free water surface wetland, southwest China

Qibin Liang; Ting Chen; Yanxia Wang; Lei Gao; Lei Hou

doi:10.1016/j.envpol.2022.119612

Seasonal variation in release characteristics and mechanisms of sediment phosphorus to the overlying water in a free water surface wetland, southwest China

Environ Pollut. 2022 Sep 1:308:119612. doi: 10.1016/j.envpol.2022.119612. Epub 2022 Jun 11.

Authors

Qibin Liang¹, Ting Chen², Yanxia Wang², Lei Gao³, Lei Hou⁴

Affiliations

¹ College of Ecology and Environment, Southwest Forestry University, Kunming, 650224, China; Yunnan Key Laboratory of Plateau Wetland Conservation, Restoration and Ecological Services, Southwest Forestry University, Kunming, 650224, China.
² College of Ecology and Environment, Southwest Forestry University, Kunming, 650224, China.
³ Guangdong Provincial Key Laboratory of Applied Botany, Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China.
⁴ College of Ecology and Environment, Southwest Forestry University, Kunming, 650224, China; Yunnan Key Laboratory of Plateau Wetland Conservation, Restoration and Ecological Services, Southwest Forestry University, Kunming, 650224, China. Electronic address: leihou@swfu.edu.cn.

PMID: 35700881
DOI: 10.1016/j.envpol.2022.119612

Abstract

Geochemical cycling of iron (Fe) mediated by sediment microbes drives the remobilization of phosphorus (P). Understanding the underlying mechanism is essential for the evaluation of P retention by wetlands. The diffusive gradients in thin film (DGT) and 16S rDNA sequencing techniques were combined to explore seasonal variations in the remobilization mechanism of sediment P in a free water surface wetland in southwest China. A significantly positive correlation between labile P and Fe concentrations was found from the sediment profiles, indicating coupled remobilization of Fe and P in the sediment. Fe-reducing bacterial genera, particularly Sphingomonas and Geothermobacter, were responsible for the reductive dissolution of Fe oxides and subsequent P release in sediment. The efflux of sediment P was higher in the rainy season (95 ± 87 ng cm^-2 d^-1) than in the dry season (39 ± 29 ng cm^-2 d^-1). Based on the significantly positive relationship between the efflux and total concentration of sediment P, we propose a promising regression equation for quantifying the release risk of sediment P. The Luoshijiang Wetland exhibited a higher release potential as indicated by a greater regression slope (0.558) compared to the other water bodies (0.055), which was mainly attributed to the lower labile Fe:P molar ratio in the sediment. Based on estimations of the diffusive flux of P at the sediment-water interface, sediment contributed more than 172 and 413 g of P per day to the water column in the dry and rainy seasons, respectively, accounting for 14.0% and 1.9% of the P mass in the surface water of the wetland.

Keywords: Free water surface wetland; Iron-reducing bacteria; P legacy; Release flux; Sediment-water interface.

MeSH terms

China
Environmental Monitoring / methods
Geologic Sediments
Phosphorus* / analysis
Seasons
Water
Water Pollutants, Chemical* / analysis
Wetlands

Substances

Water Pollutants, Chemical
Water
Phosphorus