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Thomas W. May

Publications and source records attributed to Thomas W. May.

45 records · Page 3Linked to original sources
USGS2004

Summary of total mercury concentrations in fillets of selected sport fishes collected during 2000-2003 from Lake Natoma, Sacramento County, California

This report summarizes results of total mercury measurements in skinless fillets of sport fishes collected during August 2000, September?October 2002, and July 2003 from Lake Natoma, a small (8,760 acre-feet) afterbay for Folsom Dam on the lower American River. The primary objective of the study was to determine if mercury concentrations in fillets approached or exceeded guidelines for human consumption. The Food and Drug Administration (FDA) human-health action level for methylmercury in commercially caught fish is 1.0 ?g/g (microgram per gram); the U.S. Environmental Protection Agency (USEPA) human-health criterion for methylmercury residue in fish tissue is 0.30 ?g/g. Wet weight concentrations of total mercury in skinless fillets were as high as 0.19 ?g/g in bluegill (Lepomis macrochirus), 0.39 ?g/g in redear sunfish (L. microlophus), 1.02 ?g/g in largemouth bass (Micropterus salmoides), and 1.89 ?g/g in channel catfish (Ictalurus punctatus). Maximum concentrations of mercury in other fish species varied from 0.10 ?g/g in rainbow trout (Oncorhynchus mykiss) to 0.56 ?g/g in white catfish (A-meiurus catus). Altogether, 1 of 86 largemouth bass and 11 of 11 channel catfish exceeded the FDA human-health action level. In addition, 1 of 20 redear sunfish, 26 of 86 largemouth bass, 2 of 3 spotted bass (M. punctulatus), 1 of 1 brown bullhead (A. nebulosus), and 1 of 1 white catfish exceeded the USEPA human-health criterion. These results indicate that some fish species inhabiting Lake Natoma contain undesirably high concentrations of mercury in their skinless fillets.

Data Series↗
USGS2001

Toxicity and bioavailability of metals in the Missouri River adjacent to a lead refinery

This study is an evaluation of the potential environmental impacts of contaminated groundwater from the ASARCO metals refining facility adjacent to the Missouri River in Omaha, Nebraska. Surface waters, sediments, and sediment pore waters were collected from the Burt-Izard drain, which transects the facility, and from the Missouri River adjacent to the facility. Groundwater was also collected from the facility. Waters and sediments were analyzed for inorganic contaminants, and the toxicity of the waters was evaluated with the Ceriodaphnia dubia 7-day test. Concentrations of several elemental contaminants were highly elevated in the groundwater, but not in river sediment pore waters. Lead concentrations were moderately elevated in whole sediment at one site, but lead concentrations in pore waters were low due to apparent sequestration by acid-volatile sulfides. The groundwater sample was highly toxic to C. dubia , causing 100% mortality. Even at the lowest groundwater concentration tested (6.25%) C. dubia survival was reduced; however, at that concentration, reproduction was not significantly different from upstream porewater reference samples. Sediment pore waters were not toxic, except reproduction in pore water collected from one downstream site was somewhat reduced. The decrease in reproduction could not be attributed to measured elemental contaminants.

Nebraska↗
USGS1999

A lead isotope distribution study in swine tissue using ICP-MS

In the United States lead is an ubiquitous environmental pollutant that is a serious human health hazard, especially for women of childbearing age, developing fetuses, and young children. Information concerning the uptake and distribution of lead to maternal and fetal tissues during pregnancy is poorly documented. A study was designed using domestic swine and lead isotope enrichment methodology to focus on maternal absorption and distribution of lead into bone and soft tissues, including the fetal compartment, under varying conditions of oral lead exposure and during altered physiological states (pregnant vs unbred). Total lead levels and Pb207/Pb206 ratios in bone (femur and vertebra), blood, and soft tissues (liver, kidney, brain) were determined by ICP-MS. Lead in fetal tissues derived from maternal bone could be differentiated from that derived from exogenous dosing. Unbred swine absorbed much less lead than pregnant females receiving the same dose. The accuracy and precision of ICP-MS at the instrumental level and for the entire method (sample collection, digestion, and analysis) were evaluated for both Pb207/Pb206 ratios and total lead. Several changes were suggested in method design to improve both instrumental and total method precision.

Atomic Spectroscopy↗
USGS1998

A table of polyatomic interferences in ICP-MS

Spectroscopic interferences are probably the largest class of interferences in ICP-MS and are caused by atomic or molecular ions that have the same mass-to-charge as analytes of interest. Current ICP-MS instrumental software corrects for all known atomic “isobaric” interferences, or those caused by overlapping isotopes of different elements, but does not correct for most polyatomic interferences. Such interferences are caused by polyatomic ions that are formed from precursors having numerous sources, such as the sample matrix, reagents used for preparation, plasma gases, and entrained atmospheric gases.

Atomic Spectroscopy↗
USGS1997

The determination of Metals in sediment pore waters and in 1N HCl-extracted sediments by ICP-MS

Concentrations of metals in sediment interstitial water (pore water) and those extractable from sediment with weak acids can provide important information about the bioavailability and toxicological effects of such contaminants. The highly variable nature of metal concentrations in these matrices requires instrumentation with the detection limit capability of graphite furnace atomic absorption and the wide dynamic linear range capability of ICP-OES. These criteria are satisfied with ICP-MS instrumentation. We investigated the performance of ICP-MS in the determination of certain metals from these matrices. The results for three metals were compared to those determined by graphite furnace atomic absorption spectroscopy. It was concluded that ICP-MS was an excellent instrumental approach for the determination of metals in these matrices.

Atomic Spectroscopy↗
USGS1994

Evaluation of effects caused by high copper concentrations in Torch Lake, Michigan, on reproduction of yellow perch

Elevated concentrations of copper are present in Torch Lake, Michigan, an Environmental Protection Agency Superfund site. The sauger ( Stizostedion canadense ) population in Torch Lake has been extirpated and walleye ( Stizostedion vitreum ) populations are maintained by stocking. We used yellow perch ( Perca flavescens ) to determine if chronic exposure to elevated copper concentrations has reduced the reproductive success of percids. Ripe yellow perch from Torch Lake and Gratiot Lake, a reference site, were captured between 6 May and 6 June 1990. Crosses were made within each lake and between lakes (both combinations); five pairs of each type were attempted. Portions of each egg mass were reared in Torch Lake water (34 ng/mL copper) and reference site water (Rice Lake) until 4 days posthatch (20-d to 28-d). Copper concentrations were found to be over two times as high as in reference samples both in Torch Lake water and in gonads of perch from Torch Lake. The percentages of eggs hatched in Torch Lake and reference lake water were not significantly different, although a trend of reduced hatch in Torch Lake water was apparent. Likewise, no significant differences were indicated in hatching success among crosses. However, duration of hatching was significantly longer for Torch Lake egg masses than for reference lake egg masses, indicating that copper may affect reproductive success through disruption of hatch coordination with food availability or reduction of larval fitness.

Michigan↗
USGS1992

Selenium and other elements in freshwater fishes from the irrigated San Joaquin valley, California

Arsenic (As), chromium (Cr), mercury (Hg), and selenium (Se) were measured in composite whole-body samples of five fishes — bluegill ( Lepomis macrochirus ), common carp ( Cyprinus carpio ), mosquitofish ( Gambusia affinis ), largemouth bass ( Micropterus salmoides ), and Sacramento blackfish ( Orthodon microlepidotus ) — from the San Joaquin River system to determine if concentrations were elevated from exposure to agricultural subsurface (tile) drainage. Except for Cr, the concentrations of these elements in fishes from one or more sites were elevated; however, only Se approached concentrations that may adversely affect survival, growth, or reproduction in warm water fishes. Moreover, only Se among the four measured elements exhibited a geographic (spatial) pattern that coincided with known inflows of tile drainage to the San Joaquin River and its tributaries. Historical data from the Grassland Water District (Grasslands; a region exposed to concentrated tile drainage) suggested that concentrations of Se in fishes were at maximum during or shortly after 1984 and have been slightly lower since then. The recent decline of Se concentrations in fishes from the Grasslands could be temporary if additional acreages of irrigated lands in this portion of the San Joaquin Valley must be tile-drained to protect agricultural crops from rising groundwater tables

California↗
USGS1988

Trace element residues in bluegills and common carp from the lower San Joaquin River, California, and its tributaries

Whole-body samples of bluegills (Lepomis macrochirus) and common carp (Cyprinus carpio) from the San Joaquin River and two tributaries (Merced River and Salt Slough) were analyzed to determine if the concentrations of any of nine elements were elevated as a result of exposure of the fish to agricultural subsurface (tile) drainage water. Highest concentrations (μg/g dry weight) detected were as follows (first number in each pair applies to bluegills and the second to carp): arsenic (As), 0.97 and 1.5; boron (B), 14 and 20; cadmium (Cd), 0.14 and 0.27; chromium (Cr), 2.7 and 2.2; mercury (hg), 3.3 and 2.9; molybdenum (Mo), 2.8 and 3.6; nickel (Ni), 0.87 and 2.2; lead (Pb), 0.26 and 2.3; and selenium (Se), 3.2 and 5.5. The lowest concentrations were below the levels of detection, except for Hg (0.15 in bluegills and 0.12 in carp) and Se (0.43 and 0.56). As judged by comparisons with data from the National Contaminant Biomonitoring Program and other published surveys, the concentrations of B, Hg, Mo, and Se were moderately elevated in fish from several sites in the San Joaquin Valley. However, only the Se concentrations were positively correlated with water quality variables (e.g., total alkalinity, conductivity, and turbidity) known to be influenced by irrigation return flows. Historical data from one site (Salt Slough), where trace elements in whole fish have been measured since 1969, indicated that Se concentrations increased more than twofold between 1973 and 1977, but thereafter remained near 3.0 μg g−1 (dry weight basis), presumably due to the continuing practice of disposing seleniferous tile drainage water into the most convenient stream channel.

California↗