Nearshore Sedimentary Mercury Concentrations Reflect Legacy Point Sources and Variable Sedimentation Patterns Under a Natural Recovery Strategy
Autor: | Matthew J.S. Windle, Katherine E. Moir, Jeffrey J. Ridal, Brian F. Cumming |
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Rok vydání: | 2021 |
Předmět: |
Ontario
Hydrology Geologic Sediments 010504 meteorology & atmospheric sciences Environmental remediation Health Toxicology and Mutagenesis chemistry.chemical_element Sediment Mercury 010501 environmental sciences Sedimentation Contamination 01 natural sciences Paleolimnology Mercury (element) Current (stream) Rivers chemistry Environmental Chemistry Environmental science Sedimentary rock Ecosystem Water Pollutants Chemical Environmental Monitoring 0105 earth and related environmental sciences |
Zdroj: | Environmental Toxicology and Chemistry. 40:1788-1799 |
ISSN: | 1552-8618 0730-7268 |
Popis: | The St. Lawrence River at Cornwall, Ontario, Canada, received substantial inputs of mercury from local, shoreline-based industries through much of the 20th century. Although emission controls were implemented in the late 20th century to reduce the influx of mercury and other metals entering the river, legacy contamination of riverine sediments continues to be a concern. Monitored natural recovery was prescribed in 2005 to remediate contaminated sediments; however, few surveys have been undertaken to examine its effectiveness on shallow, nearshore sediments in contaminated areas. Surface sediments were collected at shallow, nearshore sites in contaminated zones and upstream reference areas to evaluate the current state of sedimentary contamination of mercury and other metals. A Getis-Ord Gi* "hot spot" analysis was employed to assess the spatial distribution of contaminants. In addition, 3 sediment cores were collected from contaminated zones and dated using radioisotopes (210 Pb) to assess sedimentation patterns over time. Results indicated that surface sediments from contaminated zones remained elevated in mercury relative to reference sites but spatial distribution of contaminants was highly heterogeneous. Dated sediment cores suggested that sedimentation was not occurring consistently across all areas; variable sedimentation and resuspension patterns over small spatial scales were likely factors driving heterogeneous sedimentary contamination. Such patterns complicate remediation strategies because unburied sediments may serve as continuing sources of contaminants to the ecosystem. Environ Toxicol Chem 2021;40:1788-1799. © 2021 SETAC. |
Databáze: | OpenAIRE |
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