A COMPARISON OF HAND- AND SPLINE-DRAWN PRECIPITATION MAPS FOR MOUNTAINOUS MONTANA1

ABSTRACT: Average annual precipitation for the period 1961–1990 was estimated for a mountainous region in Montana with a Laplacian thin-plate spline (ANUSPLIN) and compared to a hand-drawn map. Input data included latitude, longitude, and elevation from a three-arc-second U.S. Geological Survey Digital Elevation Model of the Bozeman and Billings 1 × 2 topographic quadrangles and precipitation data at 96 stations. The two maps are similar in appearance. Digital comparison of the two maps with ARC/INFO's Grid tools shows that mean annual precipitation for the hand-contoured map is 22.9 inches and for the ANUSPLIN map is 23.7 inches. Of the 5,760,000 cells, 53 percent showed no difference between ANUSPLIN and hand-drawn maps; 19 percent showed a two-inch difference, and 28 percent showed more than 2 inches difference. Input data and model output at the same location are not different (standard deviation 1.77, p-value 0.76). Hand-drawn maps show two inches more precipitation during the 1961–90 period than during the 1941–1970 period. Similarly, measured data at 73 sites for the period 1961–1990 are on average 2.4 inches higher than the same stations during the 1941–1970 period. The difference is significant (p-value > 0.0001).     

THE EFFECTS OF ARTIFICIAL CIRCULATION ON A SMALL NORTHEASTERN IMPOUNDMENT1

ABSTRACT: Artificial circulation was applied at East Sidney Lake, a small, eutrophic impoundment in New York, to improve the water quality of the reservoir and tailwater. Treatment was successful at both reducing the stability of the reservoir and maintaining higher mean oxygen concentrations in the bottom waters. Discharge waters had lower metals and phosphorus concentrations during treatment years. However, vertical temperature differences, although minimal, were still sufficient to permit chemical stratification and some phosphorus release from the sediments. Frequent mixing events during periods of low stability, and runoff from storm events, also appeared to increase transport of phosphorus into the epilimnion. Overall, treatment did not result in decreases in algal populations or improvements in water clarity.     

222RN IN THE WATER DISTRIBUTION SYSTEM OF TUCSON,ARIZONA1

ABSTRACT: A study of ²²²Rn concentrations in the water distribution system of Tucson, Arizona, revealed levels of 60 to 1260 pCi/L in domestic waters. These measurements are comparable to levels of between 80 and 1400 pCi/l for ²²²Rn found in ground water samples in the North-Central Tucson basin (Kahn et al., 1994). Estimated loss of ²²²Rn due to radioactive decay during travel from the well head to the home ranges from 8 to 50 percent.     

Underwater treatment of lead-contaminated sediment

The sediment associated with the reconstruction of a bridge pier was classifiable as hazardous by the Toxicity Characteristic Leaching Procedure (TCLP), due to elevated concentrations of lead. However, RCRA regulations do not classify the sediment as hazardous unless it is moved. RMT designed an in-situ, underwater treatment process to render the sediment nonhazardous, using phosphate-based chemistry before dredging. Subsequent sediment management was conducted without the additional regulatory requirements and costs associated with managing hazardous waste.     

Bioremediation of petroleum hydrocarbons: A flexible,variable speed technology

The bioremediation of petroleum hydrocarbons has evolved into a number of different processes. These processes include in-situ aquifer bioremediation, bioventing, biosparging, passive bioremediation with oxygen release compounds, and intrinsic bioremediation. Although often viewed as competing technologies, these processes actually form a continuum of biodegradation processes governed primarily by the interplay between oxygen or electron acceptor and carbon availability. Generally, as more carbon needs to be removed per unit time, more oxygen needs to be supplied. As the carbon availability or desired removal rate decreases, so does the electron acceptor requirement. By understanding this continuum approach, bioremediation can be applied as a flexible, variable-speed technology, where the effort can be increased or decreased through oxygen supply. This article discusses the carbon-oxygen demands of each process and the interplay between processes, and then provides operating guidelines for configuring bioremediation systems for maximum flexibility.     

Production, Purification and Activity of an Extracellular Depolymerase from Aspergillus fumigatus

A strain of Aspergillus fumigatus, which was observed to rapidly degrade poly-3-hydroxybutyrate (PHB) in a leaf compost, was found to secrete an extracellular hydrolase when grown on PHB as the sole carbon source. Isolation and characterization of the PHB hydrolase (depolymerase) from this fungus revealed that the enzyme had a molecular weight of 57 kDa, an isoelectric point of 7.2, and a PHB hydrolysis activity maxima which occurred at 70°C and pH 8.0. Affinity labeling experiments suggested that this fungal hydrolase is a type of serine esterase. The cyclic trimers of 3-hydroxybutyrate were found to reversibly inhibit the enzymes.     

A national critical loads framework for atmospheric deposition effects assessment: IV. Model selection,applications, and critical loads mapping

The critical loads approach is emerging as an attractive means for evaluating the effects of atmospheric deposition on sensitive terrestrial and aquatic ecosystems. Various approaches are available for modeling ecosystem responses to deposition and for estimating critical load values. These approaches include empirical and statistical relationships, steady-state and simple process models, and integrated-effects models. For any given ecosystem, the most technically sophisticated approach will not necessarily be the most appropriate for all applications; identification of the most useful approach depends upon the degree of accuracy needed and upon data and computational requirements, biogeochemical processes being modeled, approaches used for representing model results on regional bases, and desired degree of spatial and temporal resolution. Different approaches are characterized by different levels of uncertainty. If the limitations of individual approaches are known, the user can determine whether an approach provides a reasonable basis for decision making. Several options, including point maps, grid maps, and ecoregional maps, are available for presenting model results in a regional context. These are discussed using hypothetical examples for choosing populations and damage limits. The research described in this article has been funded by the US Environmental Protection Agency. This document has been prepared at the EPA Environmental Research Laboratory in Corvallis, Oregon, through contract #68-C8-0006 with ManTech Environmental Technology, Inc., and Interagency Agreement #1824-B014-A7 with the U.S. Department of Energy and at Oak Ridge National Laboratory managed by Martin Marietta Energy Systems, Inc., under Contract DE-AC05-84OR21400 with the US Department of Energy. Environmental Sciences Division Publication No. 3904. It has been subjected to the agency’s peer and administrative review and approved for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.     

A national critical loads framework for atmospheric deposition effects assessment: II. Defining assessment end points,indicators, and functional subregions

The United States Environmental Protection Agency, with support from the US Department of Energy and the National Oceanographic and Atmospheric Administration, has been evaluating the feasibility of an effects-based (critical loads) approach to atmospheric pollutant regulation and abatement. The rationale used to develop three of the six steps in a flexible assessment framework (Strickland and others, 1992) is presented along with a discussion of a variety of implementation approaches and their ramifications. The rationale proposes that it is necessary to provide an explicit statement of the condition of the resource that is considered valuable (assessment end point) because: (1) individual ecosystem components may be more or less sensitive to deposition, (2) it is necessary to select indicators of ecosystem condition that can be objectively measured and that reflect changes in the quality of the assessment end point, and (3) acceptable status (i.e., value of indicator and quality of assessment end point at critical load) must be defined. The rationale also stresses the importance of defining the assessment regions and subregions to improve the analysis and understanding of the indicator response to deposition. Subregional definition can be based on a variety of criteria, including informed judgment or quantitative procedures. It also depends on the geographic scale at which exposure and effects models are accurate and on data availability, resolution, and quality. The research described in this article has been funded by the US Environmental Protection Agency. This document has been prepared at the EPA Environmental Research Laboratory in Corvallis, Oregon, through contract #68-C8-0006 with ManTech Environmental Technology, Inc., and Interagency Agreement #1824-B014-A7 with the US Department of Energy and at Oak Ridge National Laboratory managed by Martin Marietta Energy Systems, Inc., under Contract DE-AC05-84OR21400 with the US Department of Energy. Environmental Sciences Division Publication No. 3903. It has been subjected to the agency’s peer and administrative review and approved for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.     

GEOGRAPHIC INFORMATION SYSTEM BASED NONPOINT POLLUTION MODELING1

ABSTRACT: The reauthorization of the Clean Water Act reemphasizes the need for regional scale monitoring and management of nonpoint pollution loads. The magnitude of the task will require that local governments and their consultants integrate information systems and modeling if they are to manage the massive data sets and conduct the array of simulations that will be needed to support the decision making processes. Interfacing geographic information systems (GIS) and nonpoint pollution modeling is a logical approach. The objective of the present study was to use the 37,000-acre area defined by the Kensington Quadrangle sheet in Montgomery County, Maryland, to show that GIS-supported nonpoint pollution modeling is practical and economically attractive. The purpose of the GIS is to estimate the spatial distribution of nonpoint nitrogen, phosphorous, zinc, lead, BOD, and sediment using a model developed by the Northern Virginia Planning District Commission. The system allows the user to change land uses in subareas to simulate the consequences of additional development or alternate management strategies. The tests show that in-house development of this type of special purpose GIS is a practical alternative to vendor supplied systems and that the required databases can be developed quite reasonably.