Abstract
Salinization is increasingly recognized as a global issue. However, the relative importance of different drivers across a broad range of ions and ecosystems is not well understood. This study examined spatial and temporal dynamics in riverine salinity (conductivity, Ca 2+ , Mg 2+ , Na + , K + , , Cl − and ) in the South Saskatchewan River Basin (SSRB), a semi‐arid, mixed land use watershed in Alberta, Canada. A significant temporal increase ( p − (≈ 1.4–3.0% yr −1 ). The observed increase in riverine Cl − loading downstream of a large urban center (≈ 1700 tonnes yr −1 ) was attributed to increasing inputs from road salt (≈ 1800 tonnes yr −1 ) and to a lesser extent municipal wastewater (≈ 400 tonnes yr −1 ). For most other salts, spatial variation was driven not by urbanization but by the proportion of salt affected soils and/or cropland. A distinct Na 2 SO 4 signal was observed at stations draining salt affected soils which strengthened over time at 7/12 sites indicating temporal trends in Na + and have been driven largely by soil processes. A strong relationship between cropland and salt chemistry across the basin suggests agricultural activities have also contributed to observed trends. Therefore, in regions with similar climatic and anthropogenic characteristics to the SSRB, multiple stressors are likely to be operating and as such, these systems may be at particular risk from salinization.