Mercury and selenium accumulation in the Colorado River food web, Grand Canyon, USA
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Abstract
Mercury (Hg) and selenium (Se) biomagnify in aquatic food webs and are toxic to fish and wildlife. The authors measured Hg and Se in organic matter, invertebrates, and fishes in the Colorado River food web at sites spanning 387 river km downstream of Glen Canyon Dam (AZ, USA). Concentrations were relatively high among sites compared with other large rivers (mean wet wt for 6 fishes was 0.17–1.59 μg g–1 Hg and 1.35–2.65 μg g–1 Se), but consistent longitudinal patterns in Hg or Se concentrations relative to the dam were lacking. Mercury increased (slope = 0.147) with δ15N, a metric of trophic position, indicating biomagnification similar to that observed in other freshwater systems. Organisms regularly exceeded exposure risk thresholds for wildlife and humans (6–100% and 56–100% of samples for Hg and Se, respectfully, among risk thresholds). In the Colorado River, Grand Canyon, Hg and Se concentrations pose exposure risks for fish, wildlife, and humans, and the findings of the present study add to a growing body of evidence showing that remote ecosystems are vulnerable to long-range transport and subsequent bioaccumulation of contaminants. Management of exposure risks in Grand Canyon will remain a challenge, as sources and transport mechanisms of Hg and Se extend far beyond park boundaries. Environ Toxicol Chem2015;9999:1–10
Study Area
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Mercury and selenium accumulation in the Colorado River food web, Grand Canyon, USA |
| Series title | Environmental Toxicology and Chemistry |
| DOI | 10.1002/etc.3077 |
| Volume | 34 |
| Issue | 10 |
| Year Published | 2015 |
| Language | English |
| Publisher | Society of Environmental Toxicology and Chemistry |
| Contributing office(s) | Fort Collins Science Center |
| Description | 10 p. |
| First page | 2385 |
| Last page | 2394 |
| Country | United States |
| State | Arizona |
| Other Geospatial | Colorado River, Grand Canyon |
| Online Only (Y/N) | N |
| Additional Online Files (Y/N) | N |
| Google Analytic Metrics | Metrics page |