Uranium-238 and radium-226 concentrations and partitioning in river sediments as indicators of shale-gas-related environmental impacts: The Kennebecasis River (New Brunswick, Canada).

内容摘要

Uranium-238 (238U) and radium-226 (226Ra) were investigated in river sediments to assess the environmental impact of low-intensity shale gas exploitation in New Brunswick, Canada. Surface sediments collected downstream of producing gas wells exhibited low but systematic radionuclide enrichment. Enrichment factors of 1.74 for 238U and 1.08 for 226Ra indicate limited impact on the Kennebecasis River in terms of contamination intensity. In contrast, radionuclide dispersion was pronounced, with elevated concentrations persisting up to 30 km downstream from the exploitation area. Sequential extraction revealed marked changes in radionuclide partitioning downstream of gas wells, with both radionuclides enriched in the more labile BCR (Community Bureau of Reference) fractions. This shift enhances radionuclide mobility and promotes long-range transport within the river system. The combined use of total concentrations and geochemical partitioning proves effective for identifying subtle but spatially extensive impacts of shale gas activities.