Abstract. Cationic aluminium species are toxic to terrestrial and aquatic life. Despite decades of acid emission reductions, accumulating evidence shows that freshwater acidification recovery is delayed in locations such as Nova Scotia, Canada. Further, spatial and temporal patterns of labile cationic forms of aluminium (Ali) remain poorly understood. Here we increase our understanding of Ali spatial and temporal patterns by measuring Ali concentrations in ten streams in acid-sensitive areas of Nova Scotia over a four-year time period. We observe widespread and frequent occurrences of Ali concentrations that exceed toxic thresholds (> 15 μg L−1). Ali patterns appear to be driven by known Ali drivers – pH, dissolved organic carbon, dissolved aluminium, and calcium – but the dominant driver and temporal patterns vary by catchment. Our results demonstrate that elevated Ali remains a threat to aquatic ecosystems. For example, our observed Ali concentrations are potentially harmful to the biologically, economically, and culturally significant Atlantic salmon (Salmo salar).
Abstract. Acid deposition released large amounts of aluminium into streams and lakes during the last century in northern Europe and eastern North America. Elevated aluminium concentrations caused major environmental concern due to aluminium's toxicity to terrestrial and aquatic organisms and led to the extirpation of wild Atlantic salmon populations. Air pollution reduction legislation that began in the 1990s in North America and Europe successfully reduced acid deposition, and the aluminium problem was widely considered solved. However, accumulating evidence indicates that freshwater systems still show delays in recovery from acidification, with poorly understood implications for aluminium concentrations. Here, we investigate spatial and temporal patterns of labile cationic forms of aluminium (Ali) from 2015 to 2018 in 10 catchments in Nova Scotia, Canada; this region was one of the hardest hit by acid deposition, although it was not considered to have an aluminium problem due to its high dissolved organic carbon (DOC) concentrations that were expected to reduce Ali concentrations. Surprisingly, our results show the widespread and frequent occurrences of Ali concentrations that exceed toxic thresholds in all sampled rivers despite high DOC concentrations. Generalized linear mixed model results reveal that DOC, instead of being inversely related to Ali, is the strongest predictor (positive) of Ali concentrations, suggesting that the recruitment properties of DOC in soils outweigh its protective properties in streams. Lastly, we find that, contrary to the common conceptualization that high Ali levels are associated with storm flow, high Ali concentrations are found during base flow. Our results demonstrate that elevated Ali concentrations in Nova Scotia continue to pose a threat to aquatic organisms, such as the biologically, economically, and culturally significant Atlantic salmon (Salmo salar).
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.
Addition of alkalinity to rivers is a previously unexplored but promising new tool to aid our global mission to reduce serious risks from climate change while restoring aquatic habitats.
<p>Effective&#160;carbon dioxide removal (CDR) strategies are urgently needed to reduce risks of climate change. Here we propose a new strategy for Ocean Alkalinity Enhancement that targets the land-to-ocean component of the inorganic carbon cycle: river-based alkalinity and weathering enhancement (RAWE). RAWE adapts freshwater acidification mitigation technology to capture CO<sub>2</sub>&#160;through mineral weathering and by increasing rivers&#8217; capacity to retain and transport bicarbonate to long-term storage in the ocean. Field experiments in Nova Scotia rivers demonstrate the proof of concept, and global-scale modelling of RAWE indicates a potential millions of tonnes of CDR per year. Results suggest that RAWE meets CDR criteria, such as scalability, permanence, safety, and ability to simply quantify the CO<sub>2</sub> removed, whilst delivering ecological co-benefits.&#160;</p>
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Copyright © 2025 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.