Tidal driven nutrient exchange between mangroves and estuary reveals a dynamic source-sink pattern

Fenfang Wang; Peng Cheng; Nengwang Chen; Yi-Ming Kuo

doi:10.1016/j.chemosphere.2020.128665

Tidal driven nutrient exchange between mangroves and estuary reveals a dynamic source-sink pattern

Chemosphere. 2021 May:270:128665. doi: 10.1016/j.chemosphere.2020.128665. Epub 2020 Oct 21.

Authors

Fenfang Wang¹, Peng Cheng², Nengwang Chen³, Yi-Ming Kuo⁴

Affiliations

¹ Key Laboratory of the Coastal and Wetland Ecosystems, College of the Environment and Ecology, Xiamen University, Xiamen, 361102, China.
² State Key Laboratory of Marine Environment Science, Xiamen University, Xiamen, 361102, China.
³ Key Laboratory of the Coastal and Wetland Ecosystems, College of the Environment and Ecology, Xiamen University, Xiamen, 361102, China; State Key Laboratory of Marine Environment Science, Xiamen University, Xiamen, 361102, China. Electronic address: nwchen@xmu.edu.cn.
⁴ School of Environmental Studies, China University of Geosciences, Wuhan, 430074, China.

PMID: 33121808
DOI: 10.1016/j.chemosphere.2020.128665

Abstract

Nitrogen (N) and phosphorus (P) are vital nutrients regulating mangrove productivity and coastal ecosystems. Understanding of the nutrient cycling and interaction between mangroves and estuary is limited. Here we show tidal-driven nutrient exchange and a dynamic source-sink pattern across the mangrove-estuary interface. Lateral nutrient fluxes were quantified based on hourly concentrations observed at a tidal creek outlet during 2016-2018 and water mass estimated by a hydrodynamic model (FVCOM). The results of nutrient fluxes suggested that mangroves always serve as a source of ammonium (NH₄-N) and dissolved reactive P (DRP) to estuary, but as a strong nitrate sink (NO₃-N). Dissolved organic components (DON and DOP) shifted from net efflux (source) in spring to net influx (sink) in summer, likely due to the changing balance of P input and biological and physicochemical processes. Mangroves decreased the overall loading of dissolved inorganic N (DIN), dissolved total N (DTN) and total P (TP) to the estuary. Nevertheless, the effluents (aquaculture wastewater and domestic sewage) discharged from the upstream area during ebb tide increased the export of nutrients, especially NH₄-N and DRP, offsetting the role of mangrove on mitigating coastal eutrophication.

Keywords: Eutrophication; Nutrient fluxes; Wetlands; Zhangjiang estuary.

MeSH terms

Ecosystem*
Environmental Monitoring
Estuaries*
Nitrogen / analysis
Nutrients
Phosphorus / analysis

Substances

Phosphorus
Nitrogen