Abstract
Glaciers in most parts of the world are retreating, releasing water and sediments to downstream rivers. Studies have found elevated levels of fallout radionuclides (FRNs) and other contaminants in glacial sediments, especially cryoconite, in European glaciers and Greenland. However, there are no equivalent studies for glaciers in North America. We report concentrations of FRNs (i.e. 137Cs, 210Pbun and 241Am) and other contaminants (i.e. metal(loids), phosphorus) in cryoconite and proglacial sediments from a glacier in British Columbia, Canada, and compare values to suspended sediments from the downstream river. The mean concentrations of 137Cs, 210Pbun and 241Am in cryoconite were 2,123 ± 74, 7,535 ± 224 and 11.5 ± 3.0 Bq kg−1, respectively, which are an order of magnitude greater than those for most soils and surficial materials. FRNs were much lower in suspended sediments and decreased with distance away from the glacier. Geochemical elements were enriched in cryoconite relative to local clastic materials and upper continental crust. Concentrations of FRNs in cryoconite were correlated with organic matter, which suggests this is important in controlling the scavenging of hydrophobic contaminants in glacial meltwater. Low concentrations of FRNs and contaminants in suspended sediments suggest that glacial meltwater and the delivery of cryoconite have limited impact on downstream aquatic ecosystems.
Highlights
It is well documented that glaciers in most parts of the world are retreating at a rapid rate due to global warming
We report the activities of 137Cs, 210Pb was measured and its unsupported component (210Pbun) and 241Am and the concentrations of other contaminants, such as trace elements, metal(loids) and phosphorus, in cryoconite and proglacial sediments from a glacier in British Columbia, Canada (Fig. 1)
The activity concentrations for the subglacial sample were below minimum detectable activity (MDA;
Summary
It is well documented that glaciers in most parts of the world are retreating at a rapid rate due to global warming. Few studies have compared FRN concentrations in cryoconite to concentrations in fluvial sediments being actively transported in downstream proglacial rivers, to assess the broader environmental and ecological significance. In this context, we report the activities of 137Cs, 210Pbun and 241Am and the concentrations of other contaminants, such as trace elements, metal(loids) and phosphorus, in cryoconite and proglacial sediments from a glacier in British Columbia, Canada (Fig. 1). Specific objectives were: 1) to determine whether the FRNs and geochemical elements in cryoconite had elevated concentrations relative to local non-glacial sources; and 2) to assess if the fluvial sediments in the receiving proglacial river had elevated concentrations of contaminants and posed a risk to aquatic ecosystems
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