Publications
Dive into our publications and explore the science from the Environmental Health Program (Toxic Substances Hydrology and Contaminant Biology).
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Mercury cycling in stream ecosystems. 3. Trophic dynamics and methylmercury bioaccumulation
Trophic dynamics (community composition and feeding relationships) have been identified as important drivers of methylmercury (MeHg) bioaccumulation in lakes, reservoirs, and marine ecosystems. The relative importance of trophic dynamics and geochemical controls on MeHg bioaccumulation in streams, however, remains poorly characterized. MeHg bioaccumulation was evaluated in eight stream ecosystems
Authors
L.C. Chasar, B. C. Scudder, A.R. Stewart, A.H. Bell, G. R. Aiken
Quality assurance and quality control in light stable isotope laboratories: A case study of Rio Grande, Texas, water samples
New isotope laboratories can achieve the goal of reporting the same isotopic composition within analytical uncertainty for the same material analysed decades apart by (1) writing their own acceptance testing procedures and putting them into their mass spectrometric or laser-based isotope-ratio equipment procurement contract, (2) requiring a manufacturer to demonstrate acceptable performance using
Authors
T. B. Coplen, H. Qi
The kinetics of iodide oxidation by the manganese oxide mineral birnessite
The kinetics of iodide (I−) and molecular iodine (I2) oxidation by the manganese oxide mineral birnessite (δ-MnO2) was investigated over the pH range 4.5–6.25. I− oxidation to iodate (IO3-) proceeded as a two-step reaction through an I2 intermediate. The rate of the reaction varied with both pH and birnessite concentration, with faster oxidation occurring at lower pH and higher birnessite concentr
Authors
P.M. Fox, J.A. Davis, G. W. Luther
Sources and transformations of nitrate from streams draining varying land uses: Evidence from dual isotope analysis
Knowledge of key sources and biogeochemical processes that affect the transport of nitrate (NO3-) in streams can inform watershed management strategies for controlling downstream eutrophication. We applied dual isotope analysis of NO3- to determine the dominant sources and processes that affect NO3- concentrations in six stream/river watersheds of different land uses. Samples were collected monthl
Authors
Douglas A. Burns, E. W. Boyer, E.M. Elliott, C. Kendall
The use of fluoride as a natural tracer in water and the relationship to geological features: Examples from the Animas River Watershed, San Juan Mountains, Silverton, Colorado
Investigations within the Silverton caldera, in southwestern Colorado, used a combination of traditional geological mapping, alteration-assemblage mapping, and aqueous geochemical sampling that showed a relationship between geological and hydrologic features that may be used to better understand the provenance and evolution of the water. Veins containing fluorite, huebnerite, and elevated molybden
Authors
Dana J. Bove, Katherine Walton-Day, Briant A. Kimball
Methylmercury enters an aquatic food web through acidophilic microbial mats in Yellowstone National Park, Wyoming
Microbial mats are a visible and abundant life form inhabiting the extreme environments in Yellowstone National Park (YNP), WY, USA. Little is known of their role in food webs that exist in the Park's geothermal habitats. Eukaryotic green algae associated with a phototrophic green/purple Zygogonium microbial mat community that inhabits low-temperature regions of acidic (pH ∼ 3.0) thermal springs w
Authors
Eric S. Boyd, S. King, J.K. Tomberlin, D. Kirk Nordstrom, D. P. Krabbenhoft, T. Barkay, G. G. Geesey
Using oxygen isotopes of phosphate to trace phosphorus sources and cycling in lake Erie
Water samples collected during three sampling trips to Lake Erie displayed oxygen isotopic values of dissolved phosphate (δ18Op) that were largely out of equilibrium with ambient conditions, indicating that source signatures may be discerned. δ18Op values in the Lake ranged from +10‰ to +17‰, whereas the equilibrium value was expected to be around +14‰. The riverine weighted average δ18Op value wa
Authors
K.E. Elsbury, A. Paytan, N.E. Ostrom, C. Kendall, M.B. Young, K. McLaughlin, M.E. Rollog, S. Watson
Temporal response of hydraulic head, temperature, and chloride concentrations to sea-level changes, Floridan aquifer system, USA
Three-dimensional density-dependent flow and transport modeling of the Floridan aquifer system, USA shows that current chloride concentrations are not in equilibrium with current sea level and, second, that the geometric configuration of the aquifer has a significant effect on system responses. The modeling shows that hydraulic head equilibrates first, followed by temperatures, and then by chlorid
Authors
J.D. Hughes, H. Leonard Vacher, W. E. Sanford
Aroclor 1248 exposure leads to immunomodulation, decreased disease resistance and endocrine disruption in the brown bullhead, Ameiurus nebulosus
The brown bullhead Ameiurus nebulosus is a species of the family Ictaluridae commonly used as a sentinel of environmental contamination. While these fish have been utilized for this purpose in areas contaminated with polychlorinated biphenyls (PCBs), few controlled, laboratory-based studies have been designed to document the effects of PCB mixtures in this species. Here, brown bullhead were expose
Authors
L. R. Iwanowicz, V. S. Blazer, S. D. McCormick, P.A. Van Veld, C. A. Ottinger
An ecological risk assessment of the acute and chronic toxicity of the herbicide picloram to the threatened bull trout (salvelinus confluentus) and the rainbow trout (onchorhyncus mykiss)
We conducted acute and chronic toxicity studies of the effects of picloram acid on the threatened bull trout (Salvelinus confluentus) and the standard coldwater surrogate rainbow trout (Oncorhynchus mykiss). Juvenile fish were chronically exposed for 30 days in a proportional flow-through diluter to measured concentrations of 0, 0.30, 0.60, 1.18, 2.37, and 4.75 mg/L picloram. No mortality of eithe
Authors
J.F. Fairchild, K.P. Feltz, L.C. Sappington, A.L. Allert, K.J. Nelson, J. Valle
Monitoring the removal of phosphate from ground water discharging through a pond-bottom permeable reactive barrier
Installation of a permeable reactive barrier to intercept a phosphate (PO4) plume where it discharges to a pond provided an opportunity to develop and test methods for monitoring the barrier’s performance in the shallow pond‐bottom sediments. The barrier is composed of zero‐valent‐iron mixed with the native sediments to a 0.6‐m depth over a 1100‐m2 area. Permanent suction, diffusion, and seepage s
Authors
T.D. McCobb, D.R. LeBlanc, A.J. Massey
Metal contamination and post-remediation recovery in the Boulder River watershed, Jefferson County, Montana
The legacy of acid mine drainage and toxic trace metals left in streams by historical mining is being addressed by many important yet costly remediation efforts. Monitoring of environmental conditions frequently is not performed but is essential to evaluate remediation effectiveness, determine whether clean-up goals have been met, and assess which remediation strategies are most effective. Extensi
Authors
Daniel M. Unruh, Stanley E Church, David A. Nimick, David L. Fey