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Lotcheris RA, Schreyers LJ, Bui TKL, Thi KVL, Nguyen HQ, Vermeulen B, van Emmerik THM. Plastic does not simply flow into the sea: River transport dynamics affected by tides and floating plants. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2024; 345:123524. [PMID: 38355090 DOI: 10.1016/j.envpol.2024.123524] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Revised: 12/20/2023] [Accepted: 02/06/2024] [Indexed: 02/16/2024]
Abstract
Plastic pollution is ubiquitous in aquatic environments worldwide. Rivers connect terrestrial and marine ecosystems, playing a key role in the transport of land-based plastic waste towards the sea. Emerging research suggests that in estuaries and tidal rivers, tidal dynamics play a significant role in plastic transport and retention dynamics. To date, observations in these systems have been limited, and plastic transport dynamics during single tidal cycles remain poorly understood. Here, we investigated plastic transport, trapping, and re-mobilization of macroplastics (> 0.5 cm) in the Saigon River, focusing on short-term dynamics of individual tidal cycles. We used GPS trackers, released at different stages of the tidal cycle (ebb, flood, neap, spring). Plastic items demonstrated dynamic and intermittent transport behavior. Items spent almost half of the time (49%) temporarily stopped, mainly due to their entrapment in vegetation, infrastructure, or deposition on riverbanks. Items were almost always re-mobilized within 10 h (85%), leading to successive phases of stopping and transport. Tidal dynamics also resulted in bidirectional transport of plastic items, with median daily total transport distance within the 40 km study reach (8.9 km day-1) over four times larger than the median daily net distance (2.0 km day-1). The median retention time of plastic items within the reach was 21 days (mean = 202 days). In total, 81% of the retrieved items were trapped within water hyacinths, emphasizing the important role of floating vegetation on river plastic transport dynamics. With this paper, we aim to provide data-driven insights into macroplastic transport and retention dynamics in a tropical tidal river. These are crucial in the design of effective intervention and monitoring strategies, and estimating net plastic emission from rivers into the sea.
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Affiliation(s)
- R A Lotcheris
- Stockholm Resilience Centre, Stockholm University, Stockholm, Sweden; Hydrology and Environmental Hydraulics, Wageningen University, Wageningen, the Netherlands.
| | - L J Schreyers
- Hydrology and Environmental Hydraulics, Wageningen University, Wageningen, the Netherlands
| | - T K L Bui
- Institute for Circular Economy Development, Vietnam National University, Ho Chi Minh City, Viet Nam
| | - K V L Thi
- Hydrology and Environmental Hydraulics, Wageningen University, Wageningen, the Netherlands; Faculty of Water Resources, Hanoi University of Natural Resources and Environment, Hanoi, Viet Nam
| | - H-Q Nguyen
- Institute for Circular Economy Development, Vietnam National University, Ho Chi Minh City, Viet Nam
| | - B Vermeulen
- Hydrology and Environmental Hydraulics, Wageningen University, Wageningen, the Netherlands
| | - T H M van Emmerik
- Hydrology and Environmental Hydraulics, Wageningen University, Wageningen, the Netherlands
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Chen Z, Li Q, Yan S, Xu J, Lin Q, Zhao Z, He Z. Development of a two-dimensional model to assess carbon dynamics and anthropogenic effects on CO 2 emissions in the Tan river, southern China. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2024; 349:119490. [PMID: 37984268 DOI: 10.1016/j.jenvman.2023.119490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Revised: 10/12/2023] [Accepted: 10/28/2023] [Indexed: 11/22/2023]
Abstract
Tidal rivers are key biochemical reaction channels along the land-ocean aquatic continuum, receiving carbon from wastewater and agricultural drains, which can considerably affect CO2 emissions. We developed a two-dimensional hydrodynamic and ecological model coupled with an inorganic carbon module along the Tan River in southern China. The simulations of and observations regarding discharge, temperature, total organic carbon (TOC), total inorganic carbon (TIC), and other common water quality variables were generally in good agreement. Based on the validated model, we employed statistical and scenario analyses to evaluate the carbon distribution, TOC and TIC budgets, and the imbalances induced by climatic and anthropogenic changes, providing insights into their potential greenhouse effect. The Tan River was consistently supersaturated with CO2 with an annual mean air-water CO2 emission flux (FCO2) of 226.1 ± 84.9 mmol m-2 d-1, and significant temporal and spatial variations of FCO2, TOC, and TIC were observed. Urban small streams tended to emit additional CO2 during wet seasons, and rural tributaries usually had an increase in TOC concentrations during the dry season. FCO2 was significantly positively correlated with air temperature and negatively correlated with total nitrogen, total phosphorus, and TOC. The annual riverine input of carbon to the urban river network was 17.37 Gg C yr-1, with 59.82% of TOC, and carbon output was 15.31 Gg C yr-1, with 66.87% of TOC. The retention rates for TOC and total carbon were 50.7% and 11.8% in the urban branch, respectively. Furthermore, warming and wastewater treatment could prevent urban river networks and downstream rivers from becoming carbon sources. Therefore, our findings suggest that riverine management strategies change the global CO2 release from tidal rivers and estuarine systems under climate change.
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Affiliation(s)
- Zhonghan Chen
- State Environmental Protection Key Laboratory of Water Environmental Simulation and Pollution Control, South China Institute of Environmental Sciences, Ministry of Ecology and Environment, Guangzhou, 510655, China.
| | - Qiuyan Li
- State Environmental Protection Key Laboratory of Water Environmental Simulation and Pollution Control, South China Institute of Environmental Sciences, Ministry of Ecology and Environment, Guangzhou, 510655, China
| | - Shibo Yan
- State Environmental Protection Key Laboratory of Water Environmental Simulation and Pollution Control, South China Institute of Environmental Sciences, Ministry of Ecology and Environment, Guangzhou, 510655, China
| | - Juan Xu
- State Environmental Protection Key Laboratory of Water Environmental Simulation and Pollution Control, South China Institute of Environmental Sciences, Ministry of Ecology and Environment, Guangzhou, 510655, China
| | - Qiaoyun Lin
- State Environmental Protection Key Laboratory of Water Environmental Simulation and Pollution Control, South China Institute of Environmental Sciences, Ministry of Ecology and Environment, Guangzhou, 510655, China
| | - Zhuangming Zhao
- State Environmental Protection Key Laboratory of Water Environmental Simulation and Pollution Control, South China Institute of Environmental Sciences, Ministry of Ecology and Environment, Guangzhou, 510655, China; Southern Marine Science and Engineering Guangdong Laboratory, Zhuhai, 519085, China.
| | - Ziying He
- Guangdong Forestry Survey and Planning Institute, Guangzhou, 510520, China; School of Marine Science, Guangdong Provincial Key Laboratory of Marine Resources and Coastal Engineering, Sun Yat-sen University, Guangzhou, 510275, China.
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Nguyen AT, Némery J, Gratiot N, Dao TS, Le TTM, Baduel C, Garnier J. Does eutrophication enhance greenhouse gas emissions in urbanized tropical estuaries? ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2022; 303:119105. [PMID: 35276252 DOI: 10.1016/j.envpol.2022.119105] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 01/24/2022] [Accepted: 03/03/2022] [Indexed: 06/14/2023]
Abstract
Estuaries are considered as important sources of the global emission of greenhouse gases (GHGs). Urbanized estuaries often experience eutrophication under strong anthropogenic activities. Eutrophication can enhance phytoplankton abundance, leading to carbon dioxide (CO2) consumption in the water column. Only a few studies have evaluated the relationship between GHGs and eutrophication in estuaries. In this study, we assessed the concentrations and fluxes of CO2, methane (CH4) and nitrous oxide (N2O) in combination with a suite of biogeochemical variables in four sampling campaigns over two years in a highly urbanized tropical estuary in Southeast Asia (the Saigon River Estuary, Vietnam). The impact of eutrophication on GHGs was evaluated through several statistical methods and interpreted by biological processes. The average concentrations of CO2, CH4 and N2O at the Saigon River in 2019-2020 were 3174 ± 1725 μgC-CO2 L-1, 5.9 ± 16.8 μgC-CH4 L-1 and 3.0 ± 4.8 μgN-N2O L-1, respectively. Their concentrations were 13-18 times, 52-332 times, and 9-37 times higher than the global mean concentrations of GHGs, respectively. While CO2 concentration had no clear seasonal pattern, N2O and CH4 concentrations significantly differed between the dry and the rainy seasons. The increase in eutrophication status along the dense urban area was linearly correlated with the increase in GHGs concentrations. The presence of both nitrification and denitrification resulted in elevated N2O concentrations in this urban area of the estuary. The high concentration of CO2 was contributed by the high concentration of organic carbon and mineralization process. GHGs fluxes at the Saigon River Estuary were comparable to other urbanized estuaries regardless of climatic condition. Control of eutrophication in urbanized estuaries through the implantation of efficient wastewater treatment facilities will be an effective solution in mitigating the global warming potential caused by estuarine emissions.
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Affiliation(s)
- An Truong Nguyen
- Univ. Grenoble Alpes, IRD, CNRS, Grenoble INP, IGE(1), F-38000, Grenoble, France; CARE, Ho Chi Minh City University of Technology (HCMUT), VNU-HCM, 268 Ly Thuong Kiet Street, District 10, Ho Chi Minh City, Viet Nam.
| | - Julien Némery
- Univ. Grenoble Alpes, IRD, CNRS, Grenoble INP, IGE(1), F-38000, Grenoble, France; CARE, Ho Chi Minh City University of Technology (HCMUT), VNU-HCM, 268 Ly Thuong Kiet Street, District 10, Ho Chi Minh City, Viet Nam
| | - Nicolas Gratiot
- Univ. Grenoble Alpes, IRD, CNRS, Grenoble INP, IGE(1), F-38000, Grenoble, France; CARE, Ho Chi Minh City University of Technology (HCMUT), VNU-HCM, 268 Ly Thuong Kiet Street, District 10, Ho Chi Minh City, Viet Nam
| | - Thanh-Son Dao
- CARE, Ho Chi Minh City University of Technology (HCMUT), VNU-HCM, 268 Ly Thuong Kiet Street, District 10, Ho Chi Minh City, Viet Nam; Vietnam National University, Ho Chi Minh City, Viet Nam
| | - Tam Thi Minh Le
- CARE, Ho Chi Minh City University of Technology (HCMUT), VNU-HCM, 268 Ly Thuong Kiet Street, District 10, Ho Chi Minh City, Viet Nam
| | - Christine Baduel
- Univ. Grenoble Alpes, IRD, CNRS, Grenoble INP, IGE(1), F-38000, Grenoble, France; CARE, Ho Chi Minh City University of Technology (HCMUT), VNU-HCM, 268 Ly Thuong Kiet Street, District 10, Ho Chi Minh City, Viet Nam
| | - Josette Garnier
- Sorbonne Université, CNRS, EPHE, UMR 7619 Metis, BP 123, Tour 56-55, Etage 4, 4 Place Jussieu, 7500, Paris, France
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Nguyen AT, Dao TS, Strady E, Nguyen TTN, Aimé J, Gratiot N, Némery J. Phytoplankton characterization in a tropical tidal river impacted by a megacity: the case of the Saigon River (Southern Vietnam). ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2022; 29:4076-4092. [PMID: 34402003 DOI: 10.1007/s11356-021-15850-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Accepted: 08/02/2021] [Indexed: 06/13/2023]
Abstract
The spatiotemporal variation of phytoplankton and their relationship with environmental variables were analyzed in the Saigon River-a tropical river in Southern Vietnam. Two longitudinal profiles were conducted during dry and rainy season at 18 sampling sites covering more than 60 km long in the river. Besides, a bi-weekly monitoring conducted in the upstream, urban area (Ho Chi Minh City-HCMC), and downstream of Saigon River was organized from December 2016 to November 2017. The major phytoplankton were diatoms (e.g., Cyclotella cf. meneghiniana, Leptocylindrus danicus, Aulacoseira granulata), cyanobacteria (Microcystis spp., Raphidiopsis raciborskii, Pseudanabaena sp.), and euglenoids (Trachelomonas volvocina). Commonly freshwater phytoplankton species and sometimes brackish water species were dominant during the monitoring. Phytoplankton abundances in dry season were much higher than in rainy season (>100 times) which was explained by a shorter riverine water residence time and higher flushing capacity during the dry season. There was a clear separation of phytoplankton abundance between the urban area and the remaining area of Saigon River because of polluted urban emissions of HCMC. Redundancy analysis shows that the environmental variables (TOC, nitrogen, pH, salinity, Mo, Mn) were the driving factors related to the dominance of L. danicus and Cyclotella cf. meneghiniana in the upstream river and urban section of Saigon River. The dominance of cyanobacterium Microcystis spp. in the downstream of Saigon River was related to higher salinity, Mg, Cu concentrations, and lower concentrations of nutrients, Mn, Co, and Mo. The dominance of potentially toxic cyanobacteria in Saigon River possesses health risk to local residents especially upon the increasing temperature context and nutrient loading into the river in the next decades.
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Affiliation(s)
- An Truong Nguyen
- Institute of Engineering, Univ. Grenoble Alpes, CNRS, IRD, Grenoble INP, IGE, F-38000, Grenoble, France.
- CARE, Ho Chi Minh City University of Technology (HCMUT), Ho Chi Minh City, Vietnam.
| | - Thanh-Son Dao
- CARE, Ho Chi Minh City University of Technology (HCMUT), Ho Chi Minh City, Vietnam
- Vietnam National University, Ho Chi Minh City, Vietnam
| | - Emilie Strady
- CARE, Ho Chi Minh City University of Technology (HCMUT), Ho Chi Minh City, Vietnam
- Aix Marseille Univ, Université de Toulon, CNRS, IRD, MIO, Marseille, France
| | - Tuyet T N Nguyen
- Institute of Engineering, Univ. Grenoble Alpes, CNRS, IRD, Grenoble INP, IGE, F-38000, Grenoble, France
- CARE, Ho Chi Minh City University of Technology (HCMUT), Ho Chi Minh City, Vietnam
| | - Joanne Aimé
- CARE, Ho Chi Minh City University of Technology (HCMUT), Ho Chi Minh City, Vietnam
| | - Nicolas Gratiot
- Institute of Engineering, Univ. Grenoble Alpes, CNRS, IRD, Grenoble INP, IGE, F-38000, Grenoble, France
- CARE, Ho Chi Minh City University of Technology (HCMUT), Ho Chi Minh City, Vietnam
| | - Julien Némery
- Institute of Engineering, Univ. Grenoble Alpes, CNRS, IRD, Grenoble INP, IGE, F-38000, Grenoble, France
- CARE, Ho Chi Minh City University of Technology (HCMUT), Ho Chi Minh City, Vietnam
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Traceability and Emission Reduction of Dissolved Inorganic Nitrogen in Minjiang Estuary, China. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 18:ijerph181910017. [PMID: 34639319 PMCID: PMC8507695 DOI: 10.3390/ijerph181910017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 09/03/2021] [Accepted: 09/12/2021] [Indexed: 11/17/2022]
Abstract
The accumulation of dissolved inorganic nitrogen (DIN) in estuaries has become a global environmental problem. A two-dimensional, hydrodynamic water quality model was constructed in this study to investigate the sources of DIN pollution in the Minjiang Estuary. The concentration response field between the stream input and DIN in the estuary was established by using the surveyed source data of the study area. A sharing coefficient method was used to calculate the contribution percentage of each outfall to derive and propose a reasonable nitrogen reduction plan. The results showed that the input of land-based nitrogen into the Minjiang River contributed more than half of the DIN in the near-shore sea; the middle and upper reaches of the Minjiang River largely influenced the estuary area (38.57%). Conversely, the estuary and the coastline accounted for a smaller proportion of only 5.24%, indicating that an integrated DIN reduction should be implemented in the estuary area of the whole river basin. The model calculations showed that the reduction results, after remediation according to the current national standards for wastewater discharge in rivers, were not satisfactory. Thus, a new scheme is proposed in this paper-the total nitrogen (TN) input from land-based sources into the Minjiang Estuary and from the Shuikou Dam to the Min'an section should be reduced to below 31.64%; simultaneously, the DIN concentration discharged from the Shuikou Dam should be controlled and maintained below 0.5 mg·L-1 (TN = 0.8 mg·L-1). These results will provide guidelines for developing strategies for the improvement of DIN and water quality in similar estuaries.
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