Publications

American kestrels (Falco sparverius) were fed diets containing methylmercury chloride (MeHg) at 0, 0.6, 1.7, 2.8, 3.9, or 5.0 µg/g (dry wt) starting approximately eight weeks before the onset of egg laying. Dietary treatment was terminated after 12 to 14 weeks, and unhatched eggs were collected for Hg analysis. Blood samples were collected after four weeks of treatment and the termination of the s

A capillary separation method that incorporates pH-mediated stacking is employed for the simultaneous determination of circulating steroid hormones in plasma from Perca flavescens (yellow perch) collected from natural aquatic environments. The method can be applied to separate eight steroid standards: progesterone, 17α,20β-dihydroxypregn-4-en-3-one, 17α-hydroxyprogesterone, testosterone, estrone,

Two toxic-unit models that estimate the toxicity of trace-metal mixtures to benthic communities were compared. The chronic criterion accumulation ratio (CCAR), a modification of biotic ligand model (BLM) outputs for use as a toxic-unit model, accounts for the modifying and competitive influences of major cations (Ca2+, Mg2+, Na+, K+, H+), anions (HCO3−, CO32−,SO42−, Cl−, S2−) and dissolved organic

Acute 96-h ammonia toxicity to three-month-old juvenile mussels (Lampsilis siliquoidea) was evaluated in four treatments (water-only, water-only with feeding, water and soil, and water and sand) using an exposure unit designed to maintain consistent pH and ammonia concentrations in overlying water and in pore water surrounding the substrates. Median effect concentrations (EC50s) for total ammonia

This is the second part of a study that evaluates the influence of nonpoint sources on the sediment quality of five adjacent streams within the metropolitan Kansas City area, central United States. Physical, chemical, and toxicity data (Hyalella azteca 28-day whole-sediment toxicity test) for 29 samples collected in 2003 were used for this evaluation, and the potential causes for the toxic effects

A new ion chromatography electrospray tandem mass spectrometry (IC-ESI/MS/MS) method has been developed for quantification and confirmation of chlorate (ClO3−) in environmental samples. The method involves the electro-chemical generation of isotopically labeled chlorate internal standard (Cl18O3−) using 18O water (H218O). The standard was added to all samples prior to analysis thereby minimizing t

This is the first part of a study that evaluates the influence of nonpoint-source contaminants on the sediment quality of five streams within the metropolitan Kansas City area, central United States. Surficial sediment was collected in 2003 from 29 sites along five streams with watersheds that extend from the core of the metropolitan area to its development fringe. Sediment was analyzed for 16 pol

Historical mining has left complex problems in catchments throughout the world. Land managers are faced with making cost-effective plans to remediate mine influences. Remediation plans are facilitated by spatial mass-loading profiles that indicate the locations of metal mass-loading, seasonal changes, and the extent of biogeochemical processes. Field-scale experiments during both low- and high-flo

Tracer tests were performed in distinct biogeochemical zones of a sand and gravel aquifer in Cape Cod, MA, to study the redox chemistry (I) and transport (Cs, I) of cesium and iodine in a field setting. Injection of iodide (I -) into an oxic zone of the aquifer resulted in oxidation of I - to molecular iodine (I2) and iodate (IO3-) over transport distances of several meters. Oxidation is attribute

We examined the prevalence of embryo malpositions and deformities in relation to total mercury (THg) and selenium (Se) concentrations in American avocet (Recurvirostra americana), black‐necked stilt (Himantopus mexicanus), and Forster's tern (Sterna forsteri) eggs in San Francisco Bay (CA, USA) during 2005 to 2007. Overall, 11% of embryos were malpositioned in eggs ≥18 d of age (n = 282) and 2% of

Atrazine, the widely used herbicide, has shown to affect the hypothalamus–pituitary–gonad axis in certain vertebrate species, but few studies have examined reproductive effects of this chemical on fish. Our study was designed to evaluate a population endpoint (egg production) in conjunction with histological (e.g., gonad development) and biochemical (e.g., hormone production) phenotypes associated

A physiologically based toxicokinetic (PBTK) model was developed to describe the uptake, distribution, and elimination of methylmercury (CH 3Hg) in female American kestrels. The model consists of six tissue compartments corresponding to the brain, liver, kidney, gut, red blood cells, and remaining carcass. Additional compartments describe the elimination of CH3Hg to eggs and growing feathers. Diet