Distribution, Drivers, and Threats of Aluminum in Groundwater in Nova Scotia, Canada

Abstract

Increased rates of acid deposition derived from the burning of fossil fuels over the last century have resulted in the acidification and increase in aluminum (Al) levels in freshwaters and soils in sensitive areas. While the acidification of surface waters such as lakes and rivers has been extensively studied, the acidification status and resulting Al concentrations in groundwater are poorly understood. Here we aim to describe the distribution of Al in groundwater across the province of Nova Scotia, Canada. We investigate the hydrogeological conditions that influence Al concentrations in groundwater and compare Al concentrations to legislated threshold levels for human and aquatic health. We found groundwater Al concentrations to be highest in areas underlain by plutonic and metamorphic bedrock types as well as surficial aquifers, with pH and organic carbon concentrations having the strongest correlation with groundwater Al concentrations. Few samples exceed the maximum acceptable concentration of 2900 µg/L released by Health Canada (2021), but these exceedances are important to highlight given the challenges with respect to Al treatment in private domestic wells and our evolving understanding of Al impacts to human health. High concentrations of Al in groundwater may also be exported to surface waters such as rivers and lakes, where they can be harmful to aquatic populations such as Atlantic salmon (Salmo salar). We recommend that private well owners test their water supplies for Al, and that further studies on Al export from groundwater to surface water be carried out in the most high-risk areas coincident with important Atlantic salmon river watersheds.

Natural background levels and driving factors of aluminum in shallow groundwater of an urbanized delta: Insight from eliminating anthropogenic‐impacted groundwaters

“…Therefore, we focus on driving factors controlling the high NBLs of Al in GUB and GUC in this study. In theory, after anthropogenic‐impacted groundwaters excluded by using the preselection method in this study, groundwater Al in residual datasets was generally resulted from natural sources including the atmospheric precipitation, the input of other Al‐rich water bodies, and the release of Al‐rich minerals in sediments (de Meyer et al, 2017; Hart et al, 2021; Huang et al, 2023).…”

“…In theory, after anthropogenic-impacted groundwaters excluded by using the preselection method in this study, groundwater Al in residual datasets was generally resulted from natural sources including the atmospheric precipitation, the input of other Al-rich water bodies, and the release of Al-rich minerals in sediments (de Meyer et al, 2017;Hart et al, 2021;. First, groundwater Al in the PRD resulted from the atmospheric precipitation should be a secondary source, because one publication has already reported that mean Al concentrations in total suspended particulate of the PRD were 2.8-3.4 ppb in recent years (Lee, 2007) and were less than one tenth of groundwater Al NBLs in the PRD (Figure 5).…”

The Integrated Use of Heavy-Metal Pollution Indices and the Assessment of Metallic Health Risks in the Phreatic Groundwater Aquifer—The Case of the Oued Souf Valley in Algeria

“…Strontium is less toxic than some other heavy metals, but excessive exposure can lead to bone problems, including changes in bone density [117]. Aluminum levels have been associated with neurological disorders such as Alzheimer's disease [118].…”

Title: Addition of Alkalinity to Rivers: a new CO2 Removal Strategy

“…Uncertainties. Further research is needed on the impacts of alkaline additions on nitrogen cycling, cyanobacterial blooms and dissolved humic substances in rivers, including possible increased mineralization of dissolved organic carbon 43 and effects of cation exchange processes during humic flocculation in estuaries. The ecological impacts of the addition of alkalinity to circumneutral rivers is yet unexplored.…”