Sustainable futures
Tackling nitrate pollution in Vietnam’s Red River Delta
International collaboration and data insights could protect southeast Asia’s giant freshwater ecosystems
Dr Virginia Panizzo’s research explores the impact of humans and climate change on freshwater ecosystems, with a focus on the lake and river deltas of southeast Asia, which are under increasing threat from urbanisation, changes in agricultural practices and climate change.
Dr Panizzo is part of an international study that worked with colleagues in Vietnam to assess the impact of such anthropogenic activities on the Red River Delta (RRD) and the environment surrounding the country’s capital, Hanoi.
Among the most pressing concerns is nitrate pollution – linked to manure from livestock, septic waste from human settlements, and chemical fertilisers used in rice paddy-dominated agriculture – which together threaten the delta’s water quality, ecosystem health, and the livelihoods of communities.
Dr Panizzo is collaborating with scientists at the Nuclear Training Center, Vietnam, to monitor the environmental impact of these stressors on the RRD system, which includes Hanoi city’s Day River.
The researchers employ Material Flow Analysis (MFA), which is an effective tool to visualise and quantify nutrient pathways from nonpoint source pollution, through the RRD. MFA findings quantified nitrogen flows and identified hotspots of pollution entering the freshwater ecosystem across the delta, including pig, cattle and poultry waste, and human sanitation systems. This permitted policy recommendations to be made on localised nutrient management strategies.
Dr Panizzo’s research, which is closely aligned with United Nations Sustainable Development Goal 14 (SDG 14) and its focus on sustainable use of aquatic ecosystems, is providing policymakers in Vietnam with evidence-informed insights into how to mitigate the impact of rapid population and intensive agricultural practices, which are overwhelming the RRD’s natural capacity to manage waste.
MFA revealed, for example, that rice fields and fishponds are the primary nitrogen inputs to the delta’s surface waters, accounting for 53–74% and 21–32% respectively. Simulations suggest that approximately 63% of nitrogen is retained within the delta, underscoring the need for internal mitigation due to the delta’s high capacity to accumulate such nutrients rather than export them downstream.
"Through our collaboration, we have been able to provide tangible policy recommendations to mitigate against these impacts, which will ultimately enhance the resilience to climate change of millions of people who live within the Red River Delta."
Dr Panizzo said: “Our eight-year, monthly dataset has highlighted the importance of changing land use practices and population expansion in driving regional water quality deterioration. Through our collaboration, we have been able to provide tangible policy recommendations to mitigate against these impacts, which will ultimately enhance the resilience to climate change of millions of people who live within the Red River Delta.”
Based on its findings, the research team proposes:
- Seasonal water redistribution: Pumping cleaner water from the Red River into the Day River during dry periods can dilute nitrate concentrations and support irrigation for spring rice crops.
- Reestablishing natural hydrological links: Enhancing connectivity between the Red and Day Rivers can improve water availability and ecosystem resilience.
- Targeted agricultural reforms: A 10% reduction in chemical fertilizer use and improved drainage practices in fishponds could significantly lower nitrogen inputs.
- Wastewater management: Increasing domestic wastewater collection to 50–70% and improving livestock manure treatment efficiency to 50% could reduce total nitrogen loads to the delta by 13–58%.
This research on the RRD exemplifies the challenges faced by large subtropical river systems, under pressure from human activity. Through international collaboration, advanced analytical tools like MFA, and evidence-based policy recommendations, there is a pathway toward restoring water quality and building climate resilience for the region’s inhabitants.
Dr Panizzo’s research was supported by the Newton Fund and the Global Challenges Research Fund, as part of its Living Deltas project.
Dr Virginia Panizzo
Dr Virginia Panizzo is an Associate Professor in Environmental Change in the School of Geography.