16/04/2026 4:21 PM GMT+7 TP HCM
On Thursday, April 16, 2026, CARE organized a research seminar presented by Dr. Nguyen Truong An (IGE/IRD).
The seminar, entitled “Contrasting agricultural and urban greenhouse gas signatures: The river-to-coast trajectory of the Mekong Delta and Saigon River” , focused on recent findings from the 2024 wet-season PLUME campaign in southern Vietnam.
Tropical river-dominated margins are globally significant sources of greenhouse gases (GHGs) to the atmosphere. However, the distinct metabolic trajectories of heavily urbanized versus diffuse agricultural catchments and their ultimate fate on the coastal shelf remain poorly resolved. Here, high-resolution, source-to-sea observations were presented to compare two contrasting systems discharging into a shared coastal ocean: the megacity-dominated Saigon River and the agricultural Mekong Delta.
By coupling approximately 96,000 continuous flow-through observations (pCO₂, CH₄, salinity) with a 101-station discrete grab network (organic carbon, nutrients, Chl-a), the study reveals clear biogeochemical contrasts. The Saigon River acts as an extreme “Urban Reactor”, driven by severe respiration of untreated organic loads, resulting in pronounced hypercapnia and spatial decoupling of greenhouse gases. In contrast, the Mekong Delta operates as a moderate “Diffuse Engine”, displaying steady, agriculture-driven baseline emissions with significantly lower respiration pressure.
Despite their vastly different inland signatures, both systems converge into a highly efficient carbon sink on the coastal shelf. Within the mid-salinity plume (15–25 PSU), the system shifts from net respiration to net primary production. Over 95% of daytime observations in this coastal zone act as a CO₂ sink, overlapping with the inner-plume Chlorophyll-a maximum.
These results highlight the role of the tropical coastal ocean as an active biological buffer, where riverine nutrients stimulate phytoplankton growth that mitigates estuarine emissions. Ongoing work integrates these observations into a coupled mechanistic model to simulate future carbon dynamics under changing anthropogenic pressures.
The seminar provided valuable insights into river–coast interactions and contributed to ongoing discussions on climate-relevant biogeochemical processes in tropical environments. CARE would like to thank Dr. Nguyen Truong An for his insightful presentation.
On 22/10/2015, CARE has organized the meeting of the Scientific Council with the chairmanship of Dr. Nicolas Gratiot - Director and Chairman of the Scientific Council, Assoc. Pro. Vo Le Phu (on behalf of Assoc. Pro. Nguyen Phuoc Dan - Deputy Chairman)
22/10/2015
Project description The availability of High Resolution Imagery (spatial, spectral, and radiometric) with an increased time revisit (Landsat-8 and now Sentinel-2) opens the way to a more detailed observation of coastal zones and inland waters (large rivers, lakes and reservoirs)
26/02/2016
On 08 September 2016, the delegation from Institute of Research for Development (IRD – France) led by Mr. Thierry Lebel - Director of the Promotion of Interdisciplinary and Intersectoriality and Mr. Frédéric Ménard
02/09/2016
The pretty work, a monography collection of 15 megacities in the world about "Water, megacities and Global Change”, has been published by UNESCO. The CARE Lab-HCMUT Researchers are honored to represent Ho Chi Minh City by contributing an article
11/10/2016
CARE Lab-HCMUT is pleased to present you our publication of the monography "Ho Chi Minh City growing with water-related challenges".
31/10/2016
CARE Lab-HCMUT and PADDI, a member of the Ho Chi Minh City delegation, participated in the 26th Environment exhibition POLLUTEC, Lyon (France), which took place from 30/11 to 02/12/2016.
22/12/2016
Tuteur: Dr. BUI Xuan ThanhAssociate Professor in Environmental Engineering,Head, Department of Water Science & Technology Faculty of Environment & Natural Resources
11/01/2017
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