Sea level rise affects groundwater arsenic concentrations in four coastal divisions of the Ganges delta: Implications for water quality sustainability.
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In Bangladesh, and especially in the groundwater of the four coastal divisions of the Ganges delta, the arsenic concentrations are above the limits set by the WHO and Bangladesh, which causes the population to experience severe health effects. Bangladesh is also susceptible to climate change, as it is heavily affected by the sea level rise and the accompanied salt water intrusion. This will change the conditions in the groundwater of the Ganges delta and subsequently affect the arsenic concentrations, but it is still unknown how, since no link has yet been found between these factors. The research question therefore is: How will the effective sea level rise affect arsenic concentrations in the groundwater of the four coastal divisions of the Ganges delta from the year 2000 until the year 2100? To research this question, Excel and SPSS are used and a literature review is conducted. Excel models the change of arsenic concentrations over time by using formulas found through the literature review. These formulas are analysed in SPSS. The results show that the effective sea level rise in Bangladesh amounts to 0.35 m between 2000 and 2100 and that arsenic concentrations will additionally change due to their relation with the molarity of bicarbonate and CO2, pH, redox potential and ferrous iron. The molarity of bicarbonate and CO2 will increase from 2000 to 2100 by 2.5 mol/L and by 0.03 mol/L. This subsequently increases the pH by 0.4, which directly influences the arsenic concentrations. The pH also has an indirect influence on arsenic through the redox potential and ferrous iron. The redox potential will decrease by 55 mV and ferrous iron will increase by 4.5 mg/L from 2000 to 2100. Together, the indirect and direct effect increase the arsenic concentration by 317 µg/L with a value of 1017 µg/L by 2100. Implications from this research are that the knowledge gap between sea level rise and the hereby changing arsenic concentrations is closed and that long-term predictions about arsenic concentrations can be done. This leads to the recommendation of implementing more long term measures to reduce the arsenic concentrations in groundwater.