Biogeochemical functioning of an urbanized tropical estuary: Implementing the generic C-GEM (reactive transport) model
| Autor: | Thanh-Son Dao, Julien Némery, Josette Garnier, Nicolas Gratiot, Vincent Thieu, Goulven Gildas Laruelle, An Truong Nguyen |
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| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
Biogeochemical cycle
Environmental Engineering 010504 meteorology & atmospheric sciences 010501 environmental sciences 01 natural sciences Environnement et pollution Dry season Phytoplankton Saigon River Estuary Environmental Chemistry Ecosystem Waste Management and Disposal 0105 earth and related environmental sciences geography geography.geographical_feature_category Ho Chi Minh megacity Self-purification Sediment Hypoxia (environmental) Estuary Pollution Technologie de l'environnement contrôle de la pollution Oceanography Vietnam Environmental science Traitement des déchets Water quality Biogeochemical modelling |
| Zdroj: | Science of the total environment, 784 |
| Popis: | Estuaries are amongst the most productive ecosystems of the land ocean continuum, but they are also under high anthropic pressures due to coastal urbanization. Too sparse observations have hindered the understanding of complex interactions between water quality and estuarine hydrodynamics and biogeochemical transformations. Until now, estuarine modelling studies have mainly focused on temperate estuarine systems in industrialized countries. This study investigates the responses of a tropical estuary to pollution load from a megacity (Ho Chi Minh City, Southern Vietnam) by applying a one-dimensional, biogeochemical estuarine model (C-GEM). The Saigon River Estuary flows through the megacity of Ho Chi Minh (HCMC) and is subject to episodic hypoxia events due to wastewater inputs from urban discharges. Good agreements are found between simulation outputs and observations for tidal propagation, salinity, total suspended sediment, and water quality variables in dry season in Saigon River Estuary. C-GEM reproduces the increases in ammonium, total organic carbon, phytoplankton and dissolved oxygen depletion in the urban section of the Saigon River as an impact of untreated wastewaters from HCMC. The steady-state version of C-GEM also reveals the formation of a pollutant cloud (30-km stretch) resulting from the combined effects of tidal fluctuation and low flushing capacity during the dry season. Furthermore, the quantification of the reaction fluxes simulated by the model demonstrates that nitrification is the main process removing NH4+ from the Saigon River. For the first time in such a type of environment, our study demonstrates the effectiveness of C-GEM at unraveling the complex interplay between biogeochemical reactions and transport in a tropical estuary with a minimized data requirement. This is significant for tropical estuaries in developing countries, where intensive monitoring programs are rare and have thus been rarely the object of modelling investigations. SCOPUS: ar.j info:eu-repo/semantics/published |
| Databáze: | OpenAIRE |
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