Simulation of 137Cs Migration over the Soil–Plant System of Peat Soils Contaminated after the Chernobyl Accident

A mathematical model was constructed to simulate the processes of ¹³⁷Cs migration in peat soils and its uptake by vegetation. Model parameters were assessed and the pattern of ¹³⁷Cs distribution over soil profile was predicted in case of peat soils, which are typical of the Russian regions contaminated after the Chernobyl accident. The ecological half-life of ¹³⁷Cs in the plant-root soil zone was calculated, and a long-term prognosis of the radionuclide uptake by plants was made.     

Characteristics of microorganisms isolated from technogenic soils of the Kama region

Microorganisms capable of degrading monocyclic and polycyclic aromatic hydrocarbons and several chlorinated aromatic compounds were isolated from soils polluted with industrial waste from chemical plants. They were identified as representatives of the genera Pseudomonas, Flavobacterium, Alcaligenes, Rhodococcus, Microbacterium, Cellulomonas, Arthrobacter, and Brevibacterium. Among them, bacteria capable of utilizing xenobiotics in a wide range of ambient temperatures and pH and in the presence of high sodium chloride concentrations were revealed.     

Evaluation of a multimedia monitoring system in Southeast Ohio

In order to estimate risk to human populations from environmental pollutants, it is necessary to have sound data on the concentrations of chemicals of concern in the affected media and knowledge of exposures of critical population subgroups to these chemicals. The Southeast Ohio Study is developing systematic and scientifically defensible methods for obtaining data on environmental concentrations in various media in the vicinity of critical receptors. This paper describes the study, discusses the technical approaches and gives some preliminary results.     

AN INEXPENSIVE WEIR AND PROPORTIONAL SAMPLER FOR MINIATURE WATERSHED ECOSYSTEMS1

ABSTRACT A weir system with a proportional sampler for use on miniature watershed ecosystems is described. Eight weir collection systems were evaluated for their ability to measure and sample inputs and outputs of soil-island ecosystems which occur on granite outcrops. The proportion of water actually collected by the weir systems was generally less than the proportion the systems were designed to sample, but adequate for supplying data needed for estimating elemental budgets. The weir systems were not able to account for 25 to 50 percent of the variation in total water passing over the cutoff wall. Several ways of improving overall performance of the weir systems are discussed.     

Coexistence: Symbiotic sharing of feeding territories and algal food by some coral reef fishes from the Western Indian Ocean

A symbiotic relationship between a damselfish (Stegastes fasciolatus) and 2 surgeonfishes (Acanthurus lineatus and A. leucosternon) is described. The damselfish, which is about 1/10 the size of the surgeonfishes, is concentrated in, and appears to prefer to be in, the feeding areas of the surgeonfishes. There is an average of one adult damselfish per adult surgeonfish feeding area. All 3 species defend their feeding areas against conspecifics and various other fishes that have similar diets, but there are few aggressive interactions between the cohabitants. Most of the interspecific defense of cohabited areas is provided by the surgeonfishes. The cohabitant species eat the same types of benthic microalgae, but only the damselfish eats microcrustaceans. It appears that the net cost to a surgeonfish of having a damselfish in its feeding area is very low because (1) biomass density of the damselfish is low, (2) it uses some food that the surgeonfishes do not use, and (3) it makes a small contribution to the defense of shared feeding areas. Even if there is a cost to the surgeonfish, the small size of the damselfish would allow it to take shelter from the surgeonfish, thus making it too costly for the surgeonfish to exclude it. Such cohabitation relationships, which may be quite common among reef fishes, represent a means by which the coexistence of species that use the same limiting resources is achieved.     

90-day oral toxicity of ziram: a thyrostatic and hepatotoxic study

Ziram, a dithiocarbamate fungicide, is extensively used in crop protection. Daily oral doses of ziram (5 and 25 mg kg(-1) day(-1)) for 30, 60 and 90 days produced significant mortality in male rats. The fungicide also caused a significant increase in the thyroid:body weight ratio, histological changes, and a reduced activity of thyroid (125)I uptake and protein bound (125)I. However, the animals did not show any change in the clinical enzyme profile of the liver, serum and brain. It is believed that ETU, the degradation product of ziram and a known antithyroid compound, is the causative agent for the high mortality, as well as for the pronounced thyrostatic and hepatotoxic effects found in the experimental animals.     

Prototype design for a closed marine system employing quarternary water processing

A small 2, 271-1 (600-gallon) prototype recirculating marine water system was designed and evaluated (26 months). The system employed a quaternary (mechanical, algal, bacterial and chemical) series of processing units with the aim of achieving long-term seawater quality and constancy without water replacement. Total ammonia (0.05±0.005 ppm), un-ionized ammonia (0.0036±0.0003 ppm), nitrite (0.10±0.014 ppm), nitrate (24.6±2.0 ppm), phosphate (14.0±2.1 ppm), dissolved oxygen (6.5–7.2 mg/l) and pH (7.80 to 8.25) were maintained at acceptable levels for the entire period. The biomass load (1.82 kg/397 l) consisted of 4 nurse sharks which were fed ad-lib twice a week. Further, low levels of total bacteria (1.5×102 bacteria/ml) and coliforms [most probable number (MPN) index 17/dl] were present in the seawater. The system design is suggested for use in laboratory and mariculture installations.     

Leaf litter breakdown in streams receiving treated and untreated metal mine drainage

Rates of alder leaf decomposition were used as an ecosystem-level measure of effects of untreated and treated acid mine drainage on two Colorado mountain streams. Untreated mine effluents had low pH and high concentrations of metals, particularly iron. Deposition of ferric hydroxide on leaf surfaces inhibited colonization by decomposers, such as fungi and aquatic insects, and thus little leaf breakdown occurred. Treated effluents had improved water quality (basic pH, low metal concentrations), but suspended flocs released by the treatment process buried leaves and reduced consumer activity. The rate of leaf breakdown was not significantly different from the rate with untreated effluents; thus improvement in water quality alone was insufficient to restore this important pathway of energy flow in headwater streams.