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Biomedical subjects

J N Beck

Publications and source records attributed to J N Beck.

14 recordsLinked to original sources
PubMed2001

Manganese species migration in soil at the Sabine National Wildlife Refuge, Louisiana.

A modified sequential extraction procedure was employed to speciate the chemical forms of Mn in sediment using flame atomic absorption spectrophotometry. Concentrations were determined in five different fractions for each sample (Mn in the exchangeable form, bound to carbonates, bound to Mn/Fe oxides, bound to organic matter and in the residual form). The determinations were made for sediments obtained from the Sabine National Wildlife Refuge while a marshland reclamation project was being conducted. Sediment samples were taken from Ship Channel dredge spoils (thought to be contaminated), an old reclamation site, a new reclamation site and a reference site. The results indicated that the Ship Channel sediments were not contaminated, but revealed an Mn "pumping" model, which proposes that additional Mn added to a similar site is concentrated near the surface soil layers by environmental conditions, which may be a cause of the observed slow recovery of vegetation at one of the more recently developed sites.

Conservation of Natural Resources↗
PubMed1995

Evaluation of soil radioactivities using pedologically based sampling techniques.

A new type of soil sampling protocol is suggested which has applicability to surveys of environmental radioactivity. Often there is a higher concentration of radionuclides in the lower B horizon than in the upper A horizon of well-drained, well-developed soils. It is recommended that soils be sampled pedologically, i.e., by soil horizon, rather than incrementally in depth. An example is given from a site in northern Louisiana where surface and/or the classical 15 cm ("six-inch") deep sampling could lead to erroneous conclusions regarding anthropogenic contamination.

Soil Pollutants, Radioactive↗
PubMed1990

Concentrations of Synthetic organic chemicals in leachate from a municipal landfill.

A study on the concentrations of synthetic organic chemicals in leachate from the municipal landfill of Lake Charles, Louisiana, was conducted from June 1987 through March 1989. The primary objective of this study was to provide information on the concentrations of synthetic organics in leachate from a typical municipal landfill. Leachate analyses yielded the presence of a variety of synthetic organic compounds at wide ranges in concentration. These compounds are potentially dangerous to human health.

Journal Article↗
PubMed1989

Variations of heavy metals and arsenic in fish and other organisms from the Calcasieu River and Lake, Louisiana.

The edible parts of several species of fish and other marine organisms inhabiting the Calcasieu River/Lake, Louisiana were analyzed for Cd, Cr, Cu, Pb, Hg, Ag, Zn and As. Concentrations of all metals measured in both intra and interspecies showed no significant variation with sample location. Differences in elemental concentrations were related to organism mobility and not to site-specific variations in metal loadings. Different species of finfish contained only trace amounts of Cd (0.02-0.08), Ag (less than 0.01-0.3), Pb (less than 0.2-0.5), and As (less than 0.1-0.3) mg kg(-1). Concentrations of Cu and Cr were highly variable, in contrast to Zn, which was present in relatively constant amounts across all species (28 +/- mg kg(-1). Sessile organisms such as oysters had the highest concentrations of heavy metals, including Cd. Periphyton and zooplankton were the only groups that showed differences in metal concentrations with sampling location.

Animals↗
PubMed1987

Periphyton as monitors for heavy metal pollution in the Calcasieu River estuary.

The levels of copper, lead, chromium, zinc, cadmium, arsenic and silver were determined in periphyton specimens obtained with a diatometer collector. Stations selected were along three important bayous of the Calcasieu River system. Distributions of some metals in the organisms were similar to those found in sediment from the same locations, while other metals appeared to be similar to water concentrations. Concentration ratios of periphyton over sediment greatly exceeded one for the metals chromium, zinc, cadmium, arsenic and silver. The concentrations of heavy metals in the periphyton appeared to yield more information about pollutants than either water or sediment samples collected at the periphyton stations.

Journal Article↗
PubMedDate not supplied

[Left caudal vena cava: report of a case].

The infrarenal part of the vena cava inferior running at the left side of the abdominal aorta has been observed in a 70 years old caucasian man without any other anomaly in the position of the abdominal viscera. This atypical vascular pattern was associated with the persistence of a rudimentary right inferior vena cava corresponding to the right supracardinal vein. The embryonic origin of this anatomical variation and its clinical importance are discussed.

Aged↗