A Systems Approach to Remediating Human Exposure to Arsenic and Fluoride From Overexploited Aquifers.
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In semiarid agricultural regions, aquifers have watered widespread economic development. Falling water tables, however, drive up energy costs and can make the water toxic for human consumption. The study area is located in central Mexico, where arsenic and fluoride are widely present at toxic concentrations in well water. We simulated the holistic outcomes from three pumping scenarios over 100years (2020-2120); (S1) pumping rates increase at a similar rate to the past 40years, (S2) remain constant, or (S3) decrease. Under scenario S1, by 2120, the depth to water table increased to 426m and energy consumption for irrigation increased to 4109 kWh/yr. Arsenic and fluoride concentrations increased from 14 to 46g/L and 1.0 to 3.6mg/L, respectively. The combined estimated IQ point decrements from drinking untreated well water lowered expected incomes in 2120 by 27% compared to what they would be with negligible exposure levels. We calculated the 100-year Net Present Value (NPV) of each scenario assuming the 2020 average crop value to water footprint ratio of 0.12 USD/m3. Without drinking water mitigation, S1 and S3 yielded relative NPVs of -5.96109 and 1.51109 USD, respectively, compared to the base case (S2). The relative NPV of providing blanket reverse osmosis treatment, while keeping pumping constant (S2), was 11.55109 USD and this gain increased when combined with decreased pumping (S3). If a high value, low water footprint crop was substituted (broccoli, 1.51 USD/m3), the net gains from increasing pumping were similar in size to those of implementing blanket drinking water treatment.
author list (cited authors)
Knappett, P., Farias, P., Miller, G. R., Hoogesteger, J., Li, Y., Mendoza-Sanchez, I., ... Terrell, D.
complete list of authors
Knappett, PSK||Farias, P||Miller, GR||Hoogesteger, J||Li, Y||Mendoza-Sanchez, I||Woodward, RT||Hernandez, H||Loza-Aguirre, I||Datta, S||Huang, Y||Carrillo, G||Roh, T||Terrell, D