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A new investigation conducted by the Hong Kong University of Science and Technology (HKUST) has uncovered a significant public health concern: roughly 17 million individuals are in danger of gastrointestinal complications stemming from high sulfate levels present in groundwater. This concerning discovery arises from the introduction of the first-ever high-resolution global map detailing groundwater sulfate distribution, initiated by the university’s School of Engineering.
Groundwater plays a crucial role as a drinking water source for billions, yet consuming groundwater with elevated sulfate concentrations can lead to serious issues like diarrhea and dehydration, particularly affecting infants, elderly individuals, and other at-risk groups. Additionally, sulfate heightens arsenic contamination in water and promotes the leaching of heavy metals due to pipeline corrosion, thus indirectly contributing to various health problems and financial burdens. For instance, the United States faces an estimated annual cost of USD 22 billion related to corrosion in its water supply systems.
“Regrettably, sulfate levels in groundwater frequently go unmonitored. This crucial yet often ignored issue has significant implications for public health and water infrastructure,” stated Prof. CHEN Guanghao, Chair Professor of Civil and Environmental Engineering and co-leading author of the study.
To explore the extent of this issue, Prof. Chen and his research team created a detailed map utilizing modern data-driven techniques. Analyzing over 17,000 sulfate concentration readings along with a variety of global geospatial data, they produced a groundbreaking map with a resolution of 1 km.
This pioneering map functions as a valuable resource for evaluating water quality. It identifies areas with high sulfate levels and highlights the key factors contributing to these issues, which include natural influences like precipitation and geology, as well as human activities such as the use of fertilizers and mining operations.
Using this map, researchers found that around 194 million individuals worldwide encounter water containing sulfate concentrations surpassing 250 mg/L, the limit advised by the World Health Organization (WHO). Water at this concentration may have an unpleasant taste.
Even more concerning, approximately 17 million individuals are at significant health risk due to their residence in areas where sulfate levels exceed 500 mg/L — a concentration linked to gastrointestinal health problems.
The findings were published in the journal Environmental Science & Technology, in an article titled “Understanding the Global Distribution of Groundwater Sulfate and Assessing Population at Risk.”
“Our findings provide a much-needed global perspective, enabling policymakers to better prioritize strategies for intervention and enhance water quality in at-risk areas,” remarked postdoctoral researcher Dr. ZHANG Zi, another co-leading author of the research.
The map identifies regions with prevalent sulfate issues, especially in South Asia and North Africa, where millions depend on untreated groundwater for their drinking needs. While geological factors are predominant contributors in certain locations, human activities such as industrial waste and farming methods greatly influence sulfate levels in others. This variability highlights the necessity for tailored sulfate management strategies.
XIAO Chengyu, the first author and a PhD student, emphasized that sulfate contamination poses risks not just to human health, but also to the environment at large.
“Elevated sulfate levels can cause ecological harm by fostering eutrophication in aquatic environments, releasing detrimental nutrients like phosphorus. Given the exacerbating effects of climate change and urban expansion, sulfate problems are likely to intensify, posing further risks to global water quality and availability,” she explained.
This study, carried out in partnership with Princeton University, City University of Hong Kong, and Beijing Institute of Technology, underscores the urgent need to include sulfate considerations in global water safety measures. It offers an essential framework for policymakers, water resource management professionals, and researchers to develop effective and sustainable strategies in the face of escalating environmental and public health challenges.
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