| Autor: |
Janssen SE; US Geological Survey Upper Midwest Water Science Center, One Gifford Pinchot Drive,, Madison, Wisconsin 53726, United States., Kotalik CJ; US Geological Survey Columbia Environmental Research Center, 4200 New Haven Rd, Columbia, Missouri 65201, United States., Willacker JJ; U.S. Geological Survey, Forest and Rangeland Ecosystem Science Center, 3200SW Jefferson Way, Corvallis, Oregon 97331, United States., Tate MT; US Geological Survey Upper Midwest Water Science Center, One Gifford Pinchot Drive,, Madison, Wisconsin 53726, United States., Pritz CMF; National Park Service, Air Resources Division, P.O. Box 25287, Denver, Colorado 80225, United States., Nelson SJ; Appalachian Mountain Club, 361 Route 16, Gorham, New Hampshire 03581, United States., Krabbenhoft DP; US Geological Survey Upper Midwest Water Science Center, One Gifford Pinchot Drive,, Madison, Wisconsin 53726, United States., Walters DM; US Geological Survey Columbia Environmental Research Center, 4200 New Haven Rd, Columbia, Missouri 65201, United States., Eagles-Smith CA; U.S. Geological Survey, Forest and Rangeland Ecosystem Science Center, 3200SW Jefferson Way, Corvallis, Oregon 97331, United States. |
| Abstrakt: |
Atmospheric mercury (Hg) emissions and subsequent transport and deposition are major concerns within protected lands, including national parks, where Hg can bioaccumulate to levels detrimental to human and wildlife health. Despite this risk to biological resources, there is limited understanding of the relative importance of different Hg sources and delivery pathways within the protected regions. Here, we used Hg stable isotope measurements within a single aquatic bioindicator, dragonfly larvae, to determine if these tracers can resolve spatial patterns in Hg sources, delivery mechanisms, and aquatic cycling at a national scale. Mercury isotope values in dragonfly tissues varied among habitat types (e.g., lentic, lotic, and wetland) and geographic location. Photochemical-derived isotope fractionation was habitat-dependent and influenced by factors that impact light penetration directly or indirectly, including dissolved organic matter, canopy cover, and total phosphorus. Strong patterns for Δ 200 Hg emerged in the western United States, highlighting the relative importance of wet deposition sources in arid regions in contrast to dry deposition delivery in forested regions. This work demonstrates the efficacy of dragonfly larvae as biosentinels for Hg isotope studies due to their ubiquity across freshwater ecosystems and ability to track variation in Hg sources and processing attributed to small-scale habitat and large-scale regional patterns. |
