Widespread diminishing anthropogenic effects on calcium in freshwaters.

ABSTRACT: Calcium (Ca) is an essential element for almost all living organisms. Here, we examined global variation and controls of freshwater Ca concentrations, using 440 599 water samples from 43 184 inland water sites in 57 countries. We found that the global median Ca concentration was 4.0 mg L^-1 with 20.7% of the water samples showing Ca concentrations ≤ 1.5 mg L^-1, a threshold considered critical for the survival of many Ca-demanding organisms. Spatially, freshwater Ca concentrations were strongly and proportionally linked to carbonate alkalinity, with the highest Ca and carbonate alkalinity in waters with a pH around 8.0 and decreasing in concentrations towards lower pH. However, on a temporal scale, by analyzing decadal trends in >200 water bodies since the 1980s, we obs

SUBMITTER: Weyhenmeyer GA 

PROVIDER: S-EPMC6639332 | biostudies-literature | 2019 Jul

REPOSITORIES: biostudies-literature