Five Aluminum Seasonality Regimes Identified in Chronically Acidified Rivers of Nova Scotia

Rotteveel, Lobke; Sterling, Shannon

doi:10.1021/acs.est.9b04872

Cited by 11 publications

(10 citation statements)

References 73 publications

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“…2, Table S1.5). The positive relationship between Ca and Al i is the opposite of what was expected (following Rotteveel and Sterling, 2019). We hypothesize that this is due to the two study sites having very low Ca concentrations (mean concentrations below 1 mg L −1 ), below which soil water Ca concentrations are too low to retard Al release.…”

Section: Potential Al I Driversmentioning

confidence: 53%

Ionic aluminium concentrations exceed thresholds for aquatic health in Nova Scotian rivers, even during conditions of high dissolved organic carbon and low flow

Sterling

MacLeod²,

Rotteveel

et al. 2020

Hydrol. Earth Syst. Sci.

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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).

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Section: Potential Al I Driversmentioning

confidence: 53%

Ionic aluminium concentrations exceed thresholds for aquatic health in Nova Scotian rivers, even during conditions of high dissolved organic carbon and low flow

Sterling

MacLeod²,

Rotteveel

et al. 2020

Hydrol. Earth Syst. Sci.

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“…Acid anions (SO 4 , NO 3 , and NO 2 ). Acid anions are assigned to the third grouping because acid deposition is usually the primary driver of freshwater acidification (Galloway et al, 1983), but it may not be a good indicator of freshwater acidification in low-C B waters or in waters with high DOC concentrations (Rotteveel and Sterling, 2020). Natural Earth projection is used, and the scale is 1 : 550 000 000.…”

Section: Resultsmentioning

confidence: 99%

“…We identify potential outliers for each time series in SWatCh using a 4 times the median absolute deviation (MAD) cut-off value. The MAD is preferred to other methods of outlier removal when the data have a skewed distribution or large outliers are present (Leys et al, 2013;Rousseeuw and Hubert, 2011), as is common in water chemistry data (e.g., Rotteveel and Sterling, 2020). Water chemistry data in SWatCh have a skewed distribution for most variables; thus, the MAD is suitable outlier screening approach.…”

Section: Flagging Of Potential Outliersmentioning

confidence: 99%

“…Catchment-scale analyses make valuable contributions to our understanding of hydrochemical processes; however, variability in catchment response to perturbation, which is potentially indicative of variability in hydrochemical processes, is difficult to evaluate in a robust manner without an approach that assesses multiple catchments/regions in a harmonized way. In the case of freshwater acidification, the water chemistry response to acid deposition may be altered by geology and land use/land cover; thus, observations made in one watershed/region may not generalize to others (e.g., Clair et al, 2011;Rotteveel and Sterling, 2020). For example, the watershed response to acid deposition is influenced by weak acids in regions with slowweathering, base cation (C B ) poor bedrock but not in regions with higher C B geology (Clair et al, 2011;Stoddard et al, 1999), and watersheds with high-intensity forest harvesting may be more strongly affected by acid deposition than those with less disturbance (Aherne et al, 2008;Feller, 2005).…”

Section: Introductionmentioning

confidence: 99%

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The Surface Water Chemistry (SWatCh) database: a standardized global database of water chemistry to facilitate large-sample hydrological research

Rotteveel

Heubach²,

Sterling³

2022

Earth Syst. Sci. Data

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Abstract. Openly accessible global-scale surface water chemistry datasets are urgently needed to detect widespread trends and problems, to help identify their possible solutions, and to determine critical spatial data gaps where more monitoring is required. Existing datasets are limited with respect to availability, sample size and/or sampling frequency, and geographic scope. These limitations inhibit researchers from tackling emerging transboundary water chemistry issues – for example, the detection and understanding of delayed recovery from freshwater acidification. Here, we begin to address these limitations by compiling the global Surface Water Chemistry (SWatCh) database, available on Zenodo (https://doi.org/10.5281/zenodo.6484939; Rotteveel and Heubach, 2021). We collect, clean, standardize, and aggregate open-access data provided by six national and international programs and research groups (United Nations Environment Programme; Hartmann et al., 2019; Environment and Climate Change Canada; the United States of America National Water Quality Monitoring Council; the European Environment Agency; and the United States National Science Foundation McMurdo Dry Valleys Long-Term Ecological Research Network) in order to compile a database containing information on sites, methods, and samples, and a geospatial information system (GIS) shapefile of site locations. We remove poor-quality data (e.g., values flagged as “suspect” or “rejected”), standardize variable naming conventions and units, and perform other data cleaning steps required for statistical analysis. The database contains water chemistry data for streams, rivers, canals, ponds, lakes, and reservoirs across seven continents, 24 variables, 33 722 sites, and over 5 million samples collected between 1960 and 2022. Similar to prior research, we identify critical spatial data gaps on the African and Asian continents, highlighting the need for more data collection and sharing initiatives in these areas, especially considering that freshwater ecosystems in these environs are predicted to be among the most heavily impacted by climate change. We identify the main challenges associated with compiling global databases – limited data availability, dissimilar sample collection and analysis methodology, and reporting ambiguity – and provide recommended solutions. By addressing these challenges and consolidating data from various sources into one standardized, openly available, high-quality, and transboundary database, SWatCh allows users to conduct powerful and robust statistical analyses of global surface water chemistry.

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“…The well samples were collected most often in the summer (47% of samples), followed by 26% in the spring, 21% in the fall and only 6% in the winter. We recommend future study on seasonal trends of Al in wells, particularly in shallow dug wells, because seasonal patterns in Al concentrations have been identified in surface waters in Nova Scotia [54].…”

Section: Discussionmentioning

confidence: 99%

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

Hart

Kennedy

Sterling

2021

Water

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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.

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Five Aluminum Seasonality Regimes Identified in Chronically Acidified Rivers of Nova Scotia

Cited by 11 publications

References 73 publications

Ionic aluminium concentrations exceed thresholds for aquatic health in Nova Scotian rivers, even during conditions of high dissolved organic carbon and low flow

Ionic aluminium concentrations exceed thresholds for aquatic health in Nova Scotian rivers, even during conditions of high dissolved organic carbon and low flow

The Surface Water Chemistry (SWatCh) database: a standardized global database of water chemistry to facilitate large-sample hydrological research

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

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