Potential health impacts of heavy-metal exposure at the Tar Creek Superfund site,Ottawa County,Oklahoma

The potential impact of exposure to heavy metals and health problems was evaluated at the Tar Creek Superfund site, Ottawa County, Oklahoma, USA. Observed versus expected mortality was calculated for selected conditions in the County and exposed cities. Excess mortality was found for stroke and heart disease when comparing the exposed County to the state but not when comparing the exposed cities to the nonexposed rest of the County. However, sample sizes in the exposed area were small, population emigration has been ongoing, and geographic coding of mortality data was incomplete. In an exposed community, 62.5% of children under the age of 6 years had blood lead levels exceeding 10 μg/dl. The relationships between heavy-metal exposure and children’s health and chronic disease in adults are suggestive that a more thorough investigation might be warranted. A number of possible environmental and health studies are suggested, including those focusing on possible central nervous system impacts. Unfortunately, the exposed population is dispersing. One lesson learned at this site is that health studies need to be conducted as soon as possible after an environmental problem is identified to both study the impact of the most acute exposures and to maximize study sample size—including those exposed to higher doses—and minimize the loss of individuals to follow-up.     

Sequence and atomic-force microscopy analysis of a matrix protein from the shell of the oyster Crassostrea virginica

Atomic-force microscopy of the major class of soluble matrix protein from the oyster Crassostrea virginica revealed that this protein forms a ring structure, perhaps rendering the NH₂-terminus unavailable to Edman degradation. Cleavage of these proteins using mild acid hydrolysis and hydroxylamine produced linear peptides that were able to be sequenced. Peptides consisted of a domain of polyserine-phosphoserine and runs of aspartic acid of 4 to 7 residues, with several other amino acids present. Hydrophobic domains were also isolated. Although phylogenetically distant, oyster shell-matrix protein is similar to the phosphophoryn isolated from dentin and, to a lesser extent, proteins isolated from verteorate bone.     

Using wind to power a groundwater circulation well—preliminary results

In areas of the country where the U.S. Department of Energy has classified the available wind resources as Class 3 or greater, the use of wind turbines to provide power to relatively small remediation systems such as groundwater circulation wells may be technically and economically feasible. Groundwater circulation wells are a good candidate technology to couple with renewable energy, because the remediation system removes contamination from the subject aquifer with no net loss of the groundwater resource, while the wind turbine does not create potentially harmful air emissions. Wind data collected in the vicinity of the former Nebraska Ordnance Plant Superfund site were used to select a wind turbine system to provide a portion of the energy necessary to power a groundwater circulation well located in an area of high trichloroethylene groundwater contamination. Because utility power was already installed at the remediation system, a 10 kW grid inter‐tie wind turbine system supplements the utility system without requiring batteries for energy storage. The historical data from the site indicate that the quantity of energy purchased correlates poorly with the quantity of groundwater treated. Preliminary data from the wind turbine system indicate that the wind turbine provides more energy than the remediation system treatment components and the well submersible pump require on a monthly average. The preliminary results indicate that the coupling of wind turbines and groundwater circulation wells may be an attractive alternative in terms of the system operation time, cost savings, and contaminant mass removal. © 2004 Wiley Periodicals, Inc.     

Survival and growth of conservation shrubs and trees,with thin-cover reclamation on acid substrate,Iowa, USA

Many abandoned strip-mine sites in midwestern USA are highly acidic and require a separate layer of low-acidity cover materials for successful revegetation. Economics and logistics often constrain this reclamation to a very thin cover. Twenty-two species of shrubs and trees were tested for 6 years of survival and growth on a thin wedge of silt loess (up to 0.75m thick) emplaced over highly acid spoils, in south-central Iowa. No weed control or maintenance was provided. The performance of 21 of the species could be categorized into 3 groups: Group 1-consistent survival (10 species); Group 2-irregular survival and growth (6 species); Group 3-little suitability for survival (5 species). Mouldy nursery stock precluded evaluation of 1 species. For most species, the most favourable survival and growth was not on the thickest loess cover (0.75 meters) because weeds became too well established. In general, the shrubs survived severe weed competition in dwarfed form until they could break through the weed canopy. But the tree species had to penetrate the weed canopy within their first few years of growth or perish. There is evidence that if weed competition were reduced or eliminated, the species in Group 2 would probably have survival and growth equivalent to those in Group 1. The use of “tubelings” for establishing shrubs and trees on thincover reclamation sites is suggested.     

Symport transport of ferrichrome-type siderophores

The energetics of ferrichrome transport by bacterial membranes are explained by a unique structural feature of the metal-laden form of the siderophore which enables complexing of alkaline-earth cations.