Salinization of inland waters as part of the anthropogenic salt cycle

Freshwater salinization is a key component of the anthropogenic salt cycle, in which human activities have altered the sources, fluxes, and flowpaths of salt ions across diverse earth systems causing a constellation of interrelated and interactive symptoms in freshwaters.  Consequences of an accelerated global salt cycle and freshwater salinization include  contaminant mobilization, loss of biodiversity, corrosion of infrastructure, and human health risks.  We show that enhanced salt inputs from road salt, wastewater, saltwater intrusion, and other disturbances are perturbing the cycles of salt and associated chemical cocktails across freshwater ecosystems.  We explore a few emerging human health implications linked to the anthropogenic salt cycle and salinization of inland waters such as: (1) saline dust from lake drying and respiratory diseases, (2) mobilization of radionuclides in groundwater and cancers, (3) arsenic and metals mobilization and saltwater intrusion, (4) hypertensive disorders and sodium restricted diets, and (5) mobilization of trace metals from soils and piped infrastructure.  We illustrate the formation and mobilization of harmful chemical cocktails of Cu, Pb, Cd, Zn, As, Ra, U, Mn, and other contaminants as driven by major ions in the anthropogenic salt cycle and a combination of geochemical processes such as: chlorocomplexation, ion exchange, changes in pH and adsorption and solubility of metals, sodium dispersion of organic matter in soils, shifting redox conditions with saltwater intrusion and complex biogeochemical interactions, and extensive changes in the abundance and forms of ligands in response to freshwater salinization.  Finally, we analyze, compare, and contrast the salt retention capacity of different strategies for stormwater management, stream restoration, riparian forest conservation, and other watershed management approaches.  If left unmanaged, salinization of inland waters can spread across progressive stages, perturb systems into alternative stable states, and contribute to losses in critical services and functions provided by natural and engineered water systems along its trajectory.

Impact/Purpose

This is an invited presentation to a special session at the American Geophysical Union meeting in Washington DC.  The presentation is based on a book chapter recently published was invited by the editors of reference book series, Treatise on Geochemistry by Elsevier.  We assembled a writing team of global experts on salinization to complete the chapter.  We described the global phenomenon of salinization across freshwater ecosystems including lakes, streams, wetlands, and groundwater, and the ways in which human activities contribute to the salinization.  We explain what alterations to the salt cycle mean for human health and the environment.  We describe and define Freshwater Salinization Syndrome and characterize the diversity of chemical cocktails formed by the direct and indirect effects of increased in dissolved salt ions in ground and surface waters.  We explore published literature about both human and environmental health impact of salinization.

Citation

Kaushal, S., P. Mayer, A. Mon, R. Shatkay, C. Maas, M. Cañedo-Argüelles, W. Hintz, B. Wessel, K. Tully, M. Rippy, AND S. Grant. Salinization of inland waters as part of the anthropogenic salt cycle. American Geophysical Union, Washington DC, DC, December 02 - 06, 2024.