Toward Safe Water for All: From Geochemistry to Equity in Accesson

Sufficient freshwater to meet the needs of humanity is increasingly lacking. A changing climate coupled with increased demand challenges our ability to provide a sufficient, safe, economically viable, and equitable water supply for domestic use, food production, and industrial processes. California is no exception and, in fact, epitomizes the stresses on water resources along with the inequities in access. Groundwater management will be the key to solving California’s, and much of the world’s, impending water crisis. Developing distributed water infiltration systems is our first hurdle, but arguably the bigger challenge is ensuring a safe groundwater supply. Every aquifer and infiltration pathway contains one or more naturally occurring metal contaminants, potentially jeopardizing the water system; the threat is realized when the contaminant transfers from the sediment solids into the water. Under present regulatory standards, arsenic exerts the greatest threat to groundwater on a state, national, and global basis. Widely distributed within sediments and released through a sequence of biogeochemical processes under oxygen-limited conditions, arsenic is released from the solids into groundwater. Despite the attention given to arsenic, a more widely distributed threat to groundwater quality may result from manganese. Released under similar conditions as arsenic, manganese resides in sediments of nearly every aquifer and at much higher concentrations than arsenic. Our work illustrates the dual threat of both arsenic and manganese in groundwater and the dangers of focusing on infiltration rates at the expense of water quality in managed aquifer recharge. Further, we show that thousands of domestic wells, many unmonitored, are contaminated with manganese. Manganese is also prevalent within community water systems (CWS), jeopardizing small CWSs even more extensively than large ones. Community-based organizations may be essential for ensuring freshwater access to the most vulnerable populations. By working in concert with and empowering CBOs to identify regions containing contaminants, developing robust testing measures, and devising means to limit exposure through policy or technology, we can provide safe domestic water for vulnerable communities.

Speaker: Sam Ying, UC Riverside