Localized recharge processes in the NE Mekong Delta and implications for groundwater quality

A synthesis of hydroclimatic, ecological, and socioeconomic data for transdisciplinary research in the Mekong

The Mekong River basin (MRB) is a transboundary basin that supports livelihoods of over 70 million inhabitants and diverse terrestrial-aquatic ecosystems. This critical lifeline for people and ecosystems is under transformation due to climatic stressors and human activities (e.g., land use change and dam construction). Thus, there is an urgent need to better understand the changing hydrological and ecological systems in the MRB and develop improved adaptation strategies. This, however, is hampered partly by lack of sufficient, reliable, and accessible observational data across the basin. Here, we fill this long-standing gap for MRB by synthesizing climate, hydrological, ecological, and socioeconomic data from various disparate sources. The data- including groundwater records digitized from the literature-provide crucial insights into surface water systems, groundwater dynamics, land use patterns, and socioeconomic changes. The analyses presented also shed light on uncertainties associated with various datasets and the most appropriate choices. These datasets are expected to advance socio-hydrological research and inform science-based management decisions and policymaking for sustainable food-energy-water, livelihood, and ecological systems in the MRB.

Influence of pH on bioclogging in porous media during managed aquifer recharge (MAR): Effectiveness and mechanism

To investigate the effect of pH on bioclogging process during managed aquifer recharge, three laboratory-scale column experiments were conducted and the relative hydraulic conductivity, bacterial cell number and the concentrations of polysaccharide, protein and EPS were measured under pH 5, 7, and 9, respectively. High-throughput sequencing was also used to determine the characteristics of bacterial community under different pH conditions. The development of bioclogging was rather different for the case of pH 5. 7, and 9; i.e., the growth process and number of bacteria differed with pH. The shortest growth period and lowest number of bacteria were observed at pH 5. In addition, the difference in bacterial EPS concentration was mainly associated with the polysaccharides. The variation in pH led to different bacterial community composition and diversity. The acid-resistant Elizabethkingia and Bacillus were abundant at pH 5, while Chryseobacterium and Klebsiella had relatively high abundances at pH 7. In contrast, the basophilic Exiguobacterium accounted for >80% of the total bacterial abundance at pH 9. This work is of great significance to explore bioclogging mechanism during MAR process, and provides insights and guidances for field-based managed aquifer recharge.