An atmospheric—terrestrial heavy metal transport model. I. model theory

A general model TOHM was developed to predict the terrestrial fate of zinc, cadmium, chromium, lead and mercury emitted by the operation of a coal-fired electric generating facility. The general model consisted of interfacing submodels describing atmospheric dispersion, precipitation, soil chemistry, and soil erosion. The models were developed from input data from a semi-arid region of the southwest United States, and except for the climatic and topographic constraints, are not site specific. TOHM was found to predict no substantial increase in indigenous levels of zinc, chromium and lead in the impact (deposition) area. However, both mercury and cadmium were predicted to be emitted and eroded to the environmental sink (receiving lake) in concentrations exceeding that naturally present in the system. TOHM is currently unvalidated, though comparison of soil erosion predictions with erosion quantities measured in the impact area gives good agreement.     

The functional significance of infanticide in a population of California ground squirrels (Spermophilus beecheyi)

Naturally-occurring infanticide was observed in a population of California ground squirrels (Spermophilus beecheyi). In four seasons, 40 infanticides were observed. All victims were post-emergent pups. Of 37 killings in which the killer was sexed 36 were by females. All infanticidal females were mothers at the time they killed, but in no case was a mother seen to kill or harm her own young. The victim was cannibalized in 22 cases and taken immediately into the killer’s burrow in 16 others. In no case did killers gain access to the victimized mother’s burrow or territory and female pups were not killed preferentially over males. In light of evolutionary explanations, infanticide in this population may best fit the resource exploitation hypothesis, in which killers commit infanticide to gain a nutritional benefit. Resource competition is a possible auxiliary explanation, since any time a female kills unrelated young she is eliminating possible competitors to her own offspring. This behavior could confer a fitness advantage on killers or it could be an adaptively neutral, alternative feeding strategy. More data are necessary to distinguish between these hypotheses. Received: 26 January 1995/Accepted after revision: 9 September 1995     

Fertility of female mice fed coumestrol and diethylstilbestrol

Coumestrol, a compound produced by various legumes which exerts estrogen-like activity in animals, and diethylstilbestrol (DES) were studied as chemical agents for controlling reproduction in mice. Female mice were fed control diets or diets containing 100 ppm coumestrol for eight days. Female mice were exposed to males and reproductive tracts examined 14 days later. Litter size was not affected by 100 ppm dietary coumestrol but feed consumption was reduced 17%. Similar trials were conducted with mice fed 1 ppm DES. Vaginal plugs were present in 50% of the females fed 1 ppm DES, but no fetal pups were present. Feed intake was reduced 37% by the DES. Levels of 0, .1, .25, .50, .75 and 1.0 ppm DES were compared in two strains of mice, Swiss and ICR. Reproduction in both strains was totally inhibited by all DES treatments. The use of DES to control rodent populations warrants further investigation.     

Zearalenone metabolism and excretion in the rat: effect of different doses

Young female rats were orally dosed with either 1 or 100 mg zearalenone kg-1 body weight; zearalenone and metabolites were measured in a 96-h collection of urine and feces by HPLC analysis. Dose had little effect on metabolites formed, or excretion route. In both treatment groups, about 55% of the oral dose was excreted in the feces, while the urine was also a major route of excretion accounting for 15-20% of the administered dose. Zearalenone and metabolites were excreted mainly in the free form, with the production of alpha-zearalenol, the most potent estrogenic metabolite, being greater than 10% of the zearalenone dose.     

Acid mine drainage from inactive eastern coal operations

The most widely used technique for abatement of acid drainage from inactive surface mines and refuse disposal areas is revegetation of a soil cover applied to the waste material. Nonetheless, acid production often persists and in some cases, limits establishment of vegetation. This paper reports on several field studies intended to determine the location of pyrite oxidation zones and migration pathways of oxidation products at inactive spoil and refuse sites.Oxygen required for pyrite oxidation is believed to he provided in the gaseous state from the atmosphere. Therefore, the oxygen concentration in unsaturated mine waste should provide an estimate of the weathering tendency in the local environment. We are currently monitoring gas composition in refuse and spoil at six sites. Barren refuse appeared to be oxygenated (>2% 0₂) in a shallow zone extending less than 1 metre below the surface during most of the year. Preliminary data from coal spoil showed that oxygen can be available throughout the unsaturated thickness, even at a revegetated site. Gas composition varied vertically and laterally at a single site and also appeared to show seasonal dependence.Hydrologic factors are also important in acid production and transport. Discharge monitoring alone does not adequately describe the mass transport of acid products through the spoil. For example, at one reclaimed mine the mean sulfate content in six monitoring wells ranged from 24% to 240% of the mean concentration at the discharge point. Sources of recharge and relative flow rates determine the contribution of a particular zone to overall discharge quality.These basic studies of acid production and transport indicate some shortcomings of standard reclamation practices at certain sites. This information will he used to develop alternative abatement technology designed to mitigate acid production at the source.     

Detection of pentachlorophenol and its glucuronide and sulfate conjugates in fish bile and exposure water

The glucuronide and sulfate conjugates of pentachlorophenol (PCP) that were present in the bile and exposure water of goldfish (Carassius auratus) were used to develop methodology to quantify PCP and its metabolites. Reverse phase HPLC with radioactivity detection separated PCP and its metabolites, and was used to verify a method of quantification that used differential extraction and scintillation counting. Extractions of aqueous phase at pH 2 or 8, with butanol, ethyl acetate, or ether indicated that ether at pH 8 best separated PCP from its metabolites. The sulfate conjugate of PCP was the major metabolite produced when goldfish were exposed to 125 micrograms 14C-PCP/l. It was present primarily in the exposure water, but also appeared in the bile.     

Evaluation of polyurethane foam as a trapping medium for herbicide vapor in air monitoring and worker inhalation studies

Polyurethane foam was an efficient adsorbent for trapping vapors of butyl esters of 2,4-D (2,4-dichlorophenoxyacetic acid) and triallate (S-(2,3,3-trichloroallyl)diisopropylthiocarbamate) in high volume air monitoring studies and of butyl esters of 2,4-D, iso-octyl ester of 2,4-D, n-butyl ester of 2,4,5-T (2,4,5-trichlorophenoxyacetic acid), bromoxynil octanoate (2,5-dibromo-4-hydroxybenzonitrile), triallate, and trifluralin (alpha, alpha, alpha-trifluoro-2,6-dinitro-N-N-dipropyl-p-toluidine) in short-term, low volume, worker inhalation exposure studies. The collected herbicide vapor was readily desorbed under soxhlet extraction with n-hexane and subsequently analyzed with electron-capture GLC. The overall efficiencies, for both trapping and extraction, were over 90%, using a single plug, for all herbicides, except triallate. In the case of triallate, two plugs in series were required for efficient trapping under the high volume air monitoring situation.     

A mathematical model of competition and colonization in a community of marine benthic algae

A mathematical model has been constructed for the algal community on the rocky shores of a Norwegian fjord. We report here on the studies of competition and colonization along a vertical transect from the upper intertidal to the sublittoral habiats. Results on species abundance and distribution (patterns of zonation) and time to reach maturity have been compared to observations both in the fjord area and in other rocky shore areas.Competition coefficients for the algae were inferred from plant morphology and shown to be in agreement with observations of algal abundance and their zone-forming ability. Competition restricts the distribution of the species, especially at the lower elevations, but does not alter their relative position. However, increasing uniform competition prolongs the time in which zone-forming can occur, and it also decreases the overall biomass which an area can sustain. Colonization by a single species may create transient stages in community development of the same order of magnitude as algae longevity, and probably also alters the zonation pattern to some degree.The simulation results indicate that the large-scale algal distribution pattern in the Hardangerfjord area results from global stability of the rocky shore community.     

The behavioral component in the meaning of places

How do people think about the physical setting in the world around them? Part of the answer to this question may be in terms of the behaviors that occur there. To explore people's knowledge of behavior—place associations, twenty places (shown via color photographs) were assessed in five ways: (a) ratings of the place's suitability for each of eleven behaviors, (b) ratings of the expected frequency of occurrence of the eleven behaviors, (c) free listings of reasons for going to each place, (d) free listings of activities-while-there and (e) free listings of activities associated with the place. Results showed that people can distinguish places on the basis of behaviors, that the behavioral component of place meaning is composed of distinct aspects, and that knowledge of behavior is related to a global, overall representation of a place.     

Cadmium concentration and distribution in corn (Zea mays L.) grown on a calcareous soil for three years after three annual sludge applications.

The disposal of digested sewage sludge on crop-producing land appeals to municipalities as an option but may pose a hazard to human and animal health if the plant material contains elevated levels of some heavy metals. This paper reports the levels of cadmium in corn grain and stover for six years -- three years with sludge applied annually and for three years after sludge applications were terminated. The cadmium concentration in corn grain from the sixth year was similar to values found in corn grown on non-sludged plots. In corn stover from treated plots the cadmium concentration was greater than from untreated plots. Our study indicated that phytotoxic levels of cadmium did not exist even though elevated levels occurred in the corn stover.