Showing papers by "United States Environmental Protection Agency published in 1986"

Regional reference sites: a method for assessing stream potentials

Abstract: Field assessments of impacted streams require a control or at least an unbiased estimate of attainable conditions. Control sites, such as upstream/downstream or wilderness sites, have proven inadequate for assessing attainable ecological conditions where the control streams differ naturally from the impacted streams to a considerable degree or where different disturbances exist than those being studied. Relatively undisturbed reference sites with watersheds in areas having the same land-surface form, soil, potential natural vegetation, and land use as are predominant in large, relatively homogeneous regions are suggested as alternative control sites. These areas are considered typical of the region and therefore the sites also are considered typical of the region because their watersheds exhibit all the terrestrial variables that make that region a region. The logical basis for developing regional reference sites lies in the ability to group watersheds and common stream types into regions by integrating available maps of terrestrial variables that influence streams. Relatively undisturbed reference sites can be selected from typical areas of the regions and from transition zones where one or two of the terrestrial variables are not the predominant one(s) of the region. These reference sites are useful for estimating attainable conditions, for evaluating temporal and spatial changes in ecological integrity, for classifying attainable uses of streams, and for setting biological and environmental criteria.

The Salmonella typhimurium/mammalian microsomal assay. A report of the U.S. Environmental Protection Agency Gene-Tox Program.

Abstract: The Salmonella assay has been in use for almost 15 years and can be defined as a routine test for mutagenicity and for predicting potential carcinogenicity It detects the majority of animal carcinogens and consequently plays an important role in safety assessment The test is also routinely used as the frontline screen for environmental samples (complex mixtures) isolated from air, water and food This role will continue to remain an area of growth as or because sample volumes associated with these testing areas are generally very limited and more extensive testing is generally impossible While this test, like all others, has some limitations, it is recommended that it be regularly included in all genetic testing batteries

Aerobic metabolism of trichloroethylene by a bacterial isolate.

Abstract: A number of soil and water samples were screened for the biological capacity to metabolize trichloroethylene. One water sample was found to contain this capacity, and a gram-negative, rod-shaped bacterium which appeared to be responsible for the metabolic activity was isolated from this sample. The isolate degraded trichloroethylene to CO2 and unidentified, nonvolatile products. Oxygen and water from the original site of isolation were required for degradation.

Acute and chronic effects of water quality criteria‐based metal mixtures on three aquatic species

Abstract: Acute and chronic toxicity tests were conducted with three aquatic species to determine the effects of metals combined as mixtures at proposed water quality criteria concentrations and at multiples of the LC50 and maximum acceptable toxicant concentration (MATC) obtained from tests on six metals. These studies were the first part of a larger research effort to derive water quality criteria for combined pollutants by the U.S. Environmental Protection Agency. Arsenic, cadmium, chromium, copper, mercury and lead combined at criterion maximum concentrations caused nearly 100% mortality in rainbow trout and daphnids (Ceriodaphnia dubia) during acute exposures. Fathead minnows were not adversely affected at this or two times this concentration, although a mixture of four to eight times the maximum value caused 15 to 60% mortality. Metals combined at the criterion average concentrations significantly reduced production of daphnid young and growth of fathead minnows after 7 and 32 d, respectively. Embryo hatchability and survival of rainbow trout were reduced at four times this criterion but not at the criterion average concentration. Acute tests with metals mixed at multiples of the LC50 indicated that the joint action of the metals was more than additive for fathead minnows and nearly strictly additive for daphnids, based on toxic units calculated from the individual components of the mixture. Chronic tests showed that the joint action was less than additive for fathead minnows but nearly strictly additive for daphnids, indicating that long-term metal interactions may be different in fish than in lower invertebrates. Adverse effects were observed at mixture concentrations of one-half to one-third the MATC for fathead minnows and daphnids, respectively, suggesting that components of mixtures at or below no effect concentrations may contribute significantly to the toxicity of a mixture on a chronic basis. These results point out the need for additional studies to determine the type and degree of interaction of toxicants because single-chemical water quality criteria may not sufficiently protect some species when other toxicants are also present.

Effect of specific surface area on the reactivity of CaO with SO2

Abstract: The paper discusses results of measuring the rate of reaction of calcined limestone (CaCO/sub 3/) with sulfur dioxide (SO/sub 2/) and oxygen (O/sub 2/) at conditions that eliminate all resistances not associated with the lime (CaO) grain surface. Reactivity increased with the square of the Brunauer, Emmett, and Teller (B.E.T.) surface area when grain size was varied as an experimental parameter. The observed effects of surface area and temperature account for the SO/sub 2/ capture reported for boiler tests of the limestone-injection process.

Uptake and depuration of organic contaminants by blue mussels ( Mytilus edulis ) exposed to environmentally contaminated sediment

Abstract: Experiments were designed to expose blue mussels (Mytilus edulis) to contaminated sediment collected from Narragansett Bay, Rhode Island, USA in 1982. Measurements were taken to allow comparisons of the uptake and depuration of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs). In addition, concentration factors in the mussels were calculated separately against the dissolved and particulate phase concentrations and the results from the exposure and control systems were compared. Both PAHs and PCBs were rapidly accumulated by the mussels exposed to the contaminated sediment. After the mussels were transferred to control seawater, individual PAHs were depurated with half-lives ranging from 12 to 30 d. Individual PCBs showed depuration half-lives which ranged from 16 to 46 d. Concentration factors in the mussels calculated against the particulate phase concentrations were very different in the exposure and control systems. Concentration factors calculated using only the dissolved phase concentrations (bioconcentration factors) showed excellent agreement in the two systems, possibly an indication that the dissolved phase was the direct source of the contaminants accumulated by the mussels. The bioconcentration factors for PCBs were higher than those of PAHs when compounds with similar n-octanol/water partition coefficients were compared.

Evaluation of the genetic activity profiles of 65 pesticides

Abstract: We have previously reported the qualitative results of a major study on 65 pesticides (Waters et al., 1982). Dose information from this investigation (either lowest effective or highest ineffective dose tested) has now been incorporated into a computerized data management system. This report focuses on the qualitative profiles of genetic activity produced by these pesticides and our efforts to classify them according to their genotoxic effects and chemical structures. Three main categories may be distinguished based on the qualitative results: Category 1 pesticides were active in most of the in vitro and in vivo assays employed. These 9 compounds include the structurally similar organophosphate insecticides, acephate, demeton, monocrotophos and trichlorfon; the phthalimide fungicide analogues, captan and folpet; and the thiocarbamate herbicide analogues, diallate, sulfallate and triallate. The 26 Category 2 compounds demonstrated fewer positive results and may be subdivided into two parts, one of which contains 12 halogenated aromatic or heterocyclic ring compounds, including the phenoxy herbicides, 2,4-D, 2,4-DB and 2,4,5-T. The remaining part of Category 2 (14 compounds) consists of structurally similar organophosphate insecticides, azinphos-methyl, crotoxyphos, disulfoton, methyl parathion; three similar ethylenebisdithiocarbamate fungicides, maneb, mancozeb, and zineb; three similar pyrethroid insecticides, allethrin, chrysanthemic acid, and ethyl chrysanthemate; and four structurally diverse compounds, cacodylic acid, dinoseb, sec. -butylamine and benomyl. The third category of 30 pesticides gave negative results in all tests and represents structurally diverse compounds. Using the computerized profile matching methodology, from 2080 possible pairwise chemical combinations of the 65 pesticides, 20 statistically significant pairs were selected. 6 groups of pesticides were identified which were substantially similar to groups of pesticides we had formed previously (Waters et al., 1982) based on genetic activity and chemical structure. The matches showed excellent qualitative and, in most cases, excellent quantitative agreement. Hence it appears that specific patterns of test results present in the genetic activity profiles are related directly to chemical structure. Conversely, the data suggests that certain groups of compounds may be recognized by a well defined series of concordant tests results. As additional data is added, comparison of test results for new chemicals with existing data for known genotoxicants should aid in the evaluation of potential genetic health hazards.

A Comparison of Direct and Indirect Methods for Estimating Environmental Benefits

Abstract: Two classes of methods are currently available to estimate consumers' valuations of improvements in environmental resources-direct and indirect. This paper reports the results of a detailed comparison of the estimated recreational benefits associated with water quality improvements using one member of each class. The findings indicate that while the estimates are quite comparable, analyst judgment played a very important role in the development of both methods.

Simulation of Aerosol Dynamics: A Comparative Review of Mathematical Models

Abstract: A comparative review of mathematical models of aerosol dynamics is presented. Three approaches are considered that are based on continuous, discrete (sectional), and parametrized (lognormal) representations of the aerosol size distribution. Simulations of coagulation and diffusion-limited condensation are performed with these modeling approaches for three case studies typical of clear, hazy, and urban atmospheric aerosol concentrations. The relative accuracies and computational costs of models based on these approaches are compared. The models based on a continuous size distribution provide an accurate solution for both coagulation and condensation. Sectional approaches simulate coagulation very well but require a fine size resolution to minimize numerical diffusion in the simulation of condensation. The parametrized model based on log-normal modal size distributions is computationally efficient but tends to overestimate the rate of coagulation and the peak aerosol concentration resulting from condensatio...

The Travel Cost Model for Lake Recreation: A Comparison of Two Methods for Incorporating Site Quality and Substitution Effects

Abstract: This paper empirically illustrates how different assumptions regarding recreationists' decision-making behavior affect the predicted changes in recreational activity given a water quality improvement. A multinomial logit model, which reallocates visits away from other sites to the improved site, predicts a smaller outward shift of the recreationist's demand curve than the more traditional travel cost model, which does not assume any reallocation of visits among sites.

In Situ Biorestoration as a Ground Water Remediation Technique

Abstract: In situ biorestoration, where applicable, is indicated as a potentially very cost-effective and environmentally acceptable remediation technology. Many contaminants in solution in ground water as well as vapors in the unsaturated zone can be completely degraded or transformed into new compounds by naturally occurring indigenous microbial populations. Undoubtedly, thousands of contamination events are remediated naturally before the contamination reaches a point of detection. The need is for methodology to determine when natural biorestoration is occurring, the stage the restoration process is in, whether enhancement of the process is possible or desirable, and what will happen if natural processes are allowed to run their course. In addition to the nature of the contaminant, several environmental factors are known to influence the capacity of indigenous microbial populations to degrade contaminants. These factors include dissolved oxygen, pH, temperature, oxidation-reduction potential, availability of mineral nutrients, salinity, soil moisture, the concentration of specific pollutants, and the nutritional quality of dissolved organic carbon in the ground water. Most enhanced in situ bioreclamation techniques available today are variations of hydrocarbon degradation procedures pioneered and patented by Raymond and coworkers at Suntech during the period 1974 to 1978. Nutrients and oxygen are introduced through injection wells and circulated through the contaminated zone by pumping one or more producing wells. The limiting factor in remediation technology is getting the contaminated subsurface material to the treatment unit or units, or in the case of in situ processes, getting the treatment process to the contaminated material. The key to successful remediation is a thorough understanding of the hydrogeologic and geochemical characteristics of the contaminated area.

Comparative evaluation of three rapid marine toxicity tests: Sea urchin early embryo growth test, sea urchin sperm cell toxicity test and microtox

Abstract: Three rapid marine toxicity tests were evaluated to determine their potential usefulness in a toxicity testing program: early embryo growth test and sperm cell toxicity test, both using the sea urchin Arbacia punctulata, and Microtox. Toxicity values (EC50s) were derived for eight organic chemicals and five metals using each system. Results were compared with LC50 values for the same chemicals from standard aquatic tests with Pimephales romelas and Daphnia magna and for the metals with Menidia menidia and Mysidopsis bahia. The EC50 values for the sea urchin early embryo growth test for organics and the LC50 values for fish and crustaceans for organics and metals with which the rapid tests were compared were from the literature. For organic chemicals, EC50s from rapid tests closely approximated LC50s and toxicity rankings, except that the sperm cell test was particularly sensitive to 2,4-pentanedione and 2-methyl-2,4-pentanediol. EC50s for metals were generally comparable with each other and with other tests using embryo and sperm of other sea urchins and oysters but not with LC50s for Mysidopsis and Menidia. These results indicate the potential value of rapid tests to screen and rank substances for toxicity. Additional information on the usefulness of these tests will be gained through continuing comparisons using a broad spectrum of single substances and complex mixtures with varying modes of action.

Lidar Observation of Elevated Pollution Layers over Los Angeles

Abstract: Elevated pollution layers are observed over Los Angeles with an aircraft equipped with a downward-looking lidar. For the first time, detailed ancillary upper-air kinematic and thermodynamic data were collected simultaneously to aid in the interpretation of these elevated layers. It is concluded that upper-level winds within the inversion, orographic effects, and thermally induced changes in the depth of the mixed layer control the evolution of these layers.

Nutrient limitation and adaptation of microbial populations to chemical transformations.

Abstract: Using field-collected periphyton and bacterial isolates, we determined adaptation lag periods for microbial transformation of p-cresol Lag periods were longer for periphyton samples collected from field sites that were low in dissolved inorganic nitrogen and phosphorus Moreover, lag periods decreased in samples amended with N or P Our data suggest that adaptation lag periods for microbial transformation of low concentrations of chemicals may correlate with limiting nutrient concentrations, and this correlation may provide a basis for predictive mathematical modeling of lag periods

Characterization of chemical waste site contamination and determination of its extent using bioassays

Abstract: Bioassays were used in a three-phase research project to (a) assess the comparative sensitivity of test organisms to known classes of chemicals, (b) determine if the chemical components in field soil and water samples of unknown chemical composition could be inferred from laboratory studies using pure chemicals and (c) investigate kriging (a relatively new statistical “mapping” technique) and bioassays as methods to define the areal extent of chemical contamination. The algal assay generally was most sensitive to samples of pure chemicals, soil elutriates and water from eight sites with known chemical contamination. Bioassays of nine samples of unknown chemical composition from the Rocky Mountain Arsenal site showed that a lettuce seed soil contact phytoassay was most sensitive. Preliminary evidence suggests that bioassays might be a useful tool in broadly identifying classes of toxic components of contaminated soil. Nearly pure formulations of insecticides and herbicides were less toxic than were their counterpart commercial formulations. This finding indicates that chemical analysis alone may fail to correctly rate the severity of possible environmental toxicity. Finally, we demonstrate that the lettuce seed phytoassay and kriging techniques can be used to map contamination in a portion of the Rocky Mountain Arsenal site and aid in cleanup decisions.

Microbial transformation rates of AZO and triphenylmethane dyes

Abstract: Using field-collected and laboratory cultures, bacterial transformation rates for one azo and two triphenylmethane dyes were studied as a means of assessing the potential degradation of these compounds in aquatic environments. Transformation was measured as loss of color by spectrophotometry, and first- and second-order transformation rate coefficients were determined. Second- order coefficients (kb) were based on total colony-forming units (CFU) of bacteria in batch cultures. Percentages of total bacteria that transformed the dyes were determined by isolating bacterial colonies from field-collected samples and testing the isolates for the capacity to transform the dyes in dilute nutrient medium. The azo dye, Acid Orange 6, was not transformed under the aerobic conditions of these studies. Basic Violet 1 was transformed and k1 values ranged from -0.003 to -0.023 h−1, with a mean (kb) of 3.5 × 10−14L CFU−1 h−1. Basic Violet 3 also was transformed and k1 values ranged from -0.002 to -0.012 h−1, with a mean kb of 2.8 × 10−14 L CFU−1 h−1. The percentage of transformer bacteria for Basic Violet 1 ranged from 6 to 28%, with a mean of 13.5%, and the range for Basic Violet 3 was 0 to 24%, with a mean of 8.32%. Therefore, the triphenylmethane dyes were transformed at similar rates, and similar fractions of the total bacterial populations were involved in the transformation.

Comparisons of single‐species, microcosm and experimental pond responses to atrazine exposure

Abstract: Results from single-species toxicity tests form the basis for guidance about concentrations of chemicals that are likely to be environmentally hazardous. Microcosm bioassays have been proposed as better tools for this purpose under some circumstances. Rarely have comparisons been made among the responses in the various test systems and those seen in natural communities. We compared the responses among single-species algal assays, a synthetic microcosm (the Taub microcosm) and experimental ponds exposed to similar concentrations of atrazine by comparing concentrations of atrazine that reduced algal activity or biomass to 50% of control values (EC50). Eight algal species were examined; mean species EC50 values for 14C uptake ranged from 37 to 308 μg/L. For the Taub microcosm, EC50 values were 103 to 159 μg/L for 14C uptake, 126 to 165 μg/L for dissolved oxygen production and 106 to 164 μg/L for dissolved oxygen consumption. Values were dependent on the time intervals selected for calculations. In the ponds, EC50 values for 14C uptake were 100 μg/L and for chlorophyll a, 82 μg/L. The basic similarity among EC50 values across test systems suggests that results from a combination of single-species assays, or the Taub microcosm, provided a reasonable estimate of the concentration of atrazine that produced similar direct effects on more natural communities.

Correspondence between spatial patterns in fish assemblages in ohio streams and aquatic ecoregions

Abstract: Land classification systems can be useful for assessing aquatic ecosystems if relationships among them exist. Because the character of an aquatic ecosystem depends to a large extent upon the character of the landscape it drains, spatial patterns in aquatic ecosystems should correspond to patterns in the landscape. To test this hypothesis, the US state of Ohio was divided into four aquatic ecoregions based on an analysis of spatial patterns in the combination of land-surface form, land use, potential natural vegetation, and soil parent material. During the period July–October 1983, fish assemblages were sampled in 46 streams that were representative of the ecoregions, and that had watersheds relatively undisturbed by human activities. Spatial patterns of the fish assemblages were examined relative to the ecoregions; distinct regional differences were identified. The assemblages differed most between the Huron/Erie Lake Plain region and the Western Allegheny Plateau region; assemblages in the Eastern Corn Belt Plains and the Erie/Ontario Lake Plain-Interior Plateau regions were intermediate. This pattern also reflects the gradient in landscape character as one moves from the northwest to the southeast of Ohio.

Experimental acidification of Little Rock Lake, Wisconsin

Abstract: The controlled acidification of a two-basin lake is described. The lake was divided by a vinyl curtain in 1984; acidification of one basin began in 1985. Target pH values of 5.5, 5.0 and 4.5 are planned for 2-yr increments. Biotic and chemical responses and internal alkalinity generation are being studied. Baseline studies, initial results at pH 5.5, and predictions of lake responses to acidification are described.

Contaminant trends in lake trout (Salvelinus namaycush) from the Upper Great Lakes

Abstract: Contaminant body burdens in lake trout (Salvelinus namaycush) from the Upper Great Lakes have been monitored since 1970 on Lake Michigan and since 1977 and 1978 on Lakes Superior and Huron by United States Environmental Protection Agency (USEPA), Great Lakes National Program Office and U.S. Fish and Wildlife Service (USFWS), Great Lakes Fishery Laboratory. Analysis of the Lake Michigan data shows that mean polychlorobiphenyl (PCB) concentrations declined from a maximum of 22.91 mg/kg in 1974 to 5.63 mg/kg in 1982. Mean total DDT concentrations declined from 19.19 mg/kg in 1970 to 2.74 mg/kg in 1982. The decline in both contaminants closely followed first order loss kinetics. If the current declines continue, PCB concentrations will decline to the U.S. Food and Drug Administration (USFDA) tolerance of 2.0 mg/kg in 1988. Mean total DDT concentrations will fall to the International Joint Commission (IJC) objective of 1.0 mg/kg by 1991. Mean dieldrin concentrations increased significantly from 0.20 mg/kg in 1971 to 0.58 mg/kg in 1979 before declining to 0.21 mg/kg in 1982. The decline from 1979–1982 followed first order loss kinetics. As this decline is not reflected in other species (bloater chubs, smelt) it will require additional years of monitoring to determine if dieldrin concentrations between 1979 and 1982 truly represents a declining trend. The only statistically significant trend other than in Lake Michigan was for total DDT which declined significantly in Lake Superior lake trout. Large data variance and the short time frame covered (1977–1982) interfered with detection of trends on Lakes Superior and Huron.

Greenhouse effect, sea level rise, and coastal zone management

Abstract: Increasing concentrations of carbon dioxide and other gases are expected to warm the earth several degrees in the next century by a mechanism known as the greenhouse effect. Such a warming could cause sea level to rise two to five feet by expanding ocean water, melting mountain glaciers, and perhaps eventually causing polar glaciers to melt and slide into the oceans. A rise in sea level of even three feet could cause substantial erosion of beaches and coastal wetlands, increased flooding, and intrusion of saltwater into rivers, bays, and aquifers. Fortunately, many of the adverse consequences can be avoided by taking timely measures in anticipation of sea level rise. Nevertheless, many coastal zone managers are reluctant to take these measures until the prospect of sea level rise becomes more certain. This article examines the implications of future sea level rise and identifies anticipatory measures that may be appropriate today in spite of current uncertainties.

Reproductive toxicity associated with acrylamide treatment in male and female rats

Abstract: The present study was designed to evaluate the influence of acrylamide (ACR) on male and female reproductive function. Male rats received ACR in drinking water (50, 100, or 200 ppm) for up to 10 wk. Copulatory behavior, semen, and (for controls and 100 ppm only) fertility and fetal outcomes were evaluated. Females received ACR (25, 50, 100 ppm) for 2 wk prior to initiation of breeding and then throughout gestation and lactation. Hindlimb splaying was apparent in the 200‐ppm males by wk 4; less severe splaying appeared in the 100‐ppm group at wk 8. Disruptions in copulatory behavior preceded the appearance of this ataxia. These disruptions in mating performance interfered with ejaculatory processes and subsequent transport of sperm, since semen was found in the uterus of only 1 of the 15 females mated with the 100‐ppm males at wk 9. Moreover, only 33% of the females mated (wk 10) to the 100‐ppm males were pregnant. Postimplantation loss was also significantly increased in this group. Hindlimb splaying appe...