Correspondence of biological condition models of California streams at statewide and regional scales

We used boosted regression trees (BRT) to model stream biological condition as measured by benthic macroinvertebrate taxonomic completeness, the ratio of observed to expected (O/E) taxa. Models were developed with and without exclusion of rare taxa at a site. BRT models are robust, requiring few assumptions compared with traditional modeling techniques such as multiple linear regression. The BRT models were constructed to provide baseline support to stressor delineation by identifying natural physiographic and human land use gradients affecting stream biological condition statewide and for eight ecological regions within the state, as part of the development of numerical biological objectives for California’s wadeable streams. Regions were defined on the basis of ecological, hydrologic, and jurisdictional factors and roughly corresponded with ecoregions. Physiographic and land use variables were derived from geographic information system coverages. The model for the entire state (n?=?1,386) identified a composite measure of anthropogenic disturbance (the sum of urban, agricultural, and unmanaged roadside vegetation land cover) within the local watershed as the most important variable, explaining 56 % of the variance in O/E values. Models for individual regions explained between 51 and 84 % of the variance in O/E values. Measures of human disturbance were important in the three coastal regions. In the South Coast and Coastal Chaparral, local watershed measures of urbanization were the most important variables related to biological condition, while in the North Coast the composite measure of human disturbance at the watershed scale was most important. In the two mountain regions, natural gradients were most important, including slope, precipitation, and temperature. The remaining three regions had relatively small sample sizes (n?≤?75 sites) and had models that gave mixed results. Understanding the spatial scale at which land use and land cover affect taxonomic completeness is imperative for sound management. Our results suggest that invertebrate taxonomic completeness is affected by human disturbance at the statewide and regional levels, with some differences among regions in the importance of natural gradients and types of human disturbance. The construction and application of models similar to the ones presented here could be useful in the planning and prioritization of actions for protection and conservation of biodiversity in California streams.     

Comparing impacts across climate models

In this paper we combine a climate-forecasting model, COSMIC, with a global impact model, GIM, to compare the market impacts of climate change projected by 14 general circulation models. Given a specific date (2100), carbon dioxide concentration (612 ppmv), and global temperature sensitivity (2.5°C), predicted impacts to economies are calculated using climate-response functions from Experimental and Cross-sectional evidence. The Cross-sectional impact model predicts small global benefits across all climate models, whereas the Experimental impact model predicts a range from small benefits to small damages. High-latitude countries are less sensitive to temperature increases than low-latitude countries because they are currently cool. Uniform global temperature changes overestimate global damages because they underestimate the benefits in polar regions and overestimate the damages in tropical regions compared to the GCM predictions.     

The Climate Impacts of Sulfate Aerosols

Sulfate aerosols (SO₄) from anthropogenic emissions of sulfur dioxide (SO₂) generally have a cooling effect. However, if SO₂ emissions fall over time, accounting for sulfate aerosols will increase the predicted warming from greenhouse gases. This paper integrates the four marker emission scenarios for CO₂ and SO₄ from the Special Report on Emissions Scenarios (SRES), the UIUC general circulation model (GCM), and a country-specific impact model (GIM) to calculate the impacts of sulfate aerosols. By 2100, lower SO₂ emissions slightly increase warming in the temperate and polar regions causing small damages in the former and small benefits in the latter. If SO₂ emissions are also lower in tropical regions, temperatures will rise causing small damages there as well. However, if SO₂ emissions rise in tropical regions, temperatures will fall leading to small benefits. This revised version was published online in July 2006 with corrections to the Cover Date.     

Applying physicochemical approaches to control phosphogypsum heavy metal releases in aquatic environment

One of the most important sources of solid waste in the Mediterranean Basin ecosystem originated from the phosphate fertilizer industries, which discharge phosphogypsum (PG) directly into aquatic environments or are stacked on stockpiles. The present study investigates metal release from PG under the influence of variable pH, increasing PG mass content, and complexing organic matter ligands. Major ions from PG leachates, grain size and charge, main functional groups along with metal leachability (Pb, Cd, Cr, Cu, and Zn) were determined using ion chromatography, laser diffraction, zetameter, Fourier transform infrared spectroscopy, and atomic absorption spectroscopy, respectively. The complete dissolution of PG recorded is at 2 g/L. Saturation and supersaturation with respect to PG may occur at concentrations of 3 and 4 g/L, respectively, revealing a clustering phenomenon leading to heavy metal encapsulation within the aggregates. Organic ligands such as citrate may trigger the cationic exchange within the PG suspension leading to ion release. As these factors are considered as specific process involving the release of contaminants from PG during storage under natural conditions, this study could set the foundations for PG remediation in aquatic environment. Organic ligands under controlled pH conditions could be utilized in treating fertilizer industrial wastes by taking into consideration the particularity of the receiving area, thus decreasing metal hazardous impact on natural media.     

Screening Approach for Principal Organic Hazardous Constituents and Products of Incomplete Combustion

The body of information presented in this paper is directed to those individuals concerned with developing or implementing screening strategies for characterizing organic emissions from incinerators and other combustion sources. The need to characterize hazardous waste incinerator emissions for multiple organic compounds has been steadily increasing for several years. The regulatory approach makes use of a type of indicator compound procedure that concentrates on principal organic hazardous constituents (POHCs). In addition to continuing interest in POHCs, interest has been growing in the types and concentrations of products of incomplete combustion (PICs). Sampling and analysis methods have been developed previously for approximately 225 of the more important POHCs and PICs. These methods may be used as components of a cost-effective screening protocol aimed at maximum characterization of emissions, whether the project budget is large or small. This paper contains a discussion of fundamental principles of several kinds of screening strategies and recommends an approach suitable for incinerators and other combustion sources. The concept of a risk-driven analysis strategy is introduced and illustrated with a simplified example.     

Identification and Quantitative Analysis of Particulate Air Contaminants by X-Ray Diffraction Spectrometry

Because of the synergistic effects which take place from the mixing of gases and particulates in ambient air, it is important that the determination of air contaminants be carried out on the sample in its native state without imposing any further chemical recombination during the analysis. Since x-ray diffraction provides a chemically passive method of analysis and yields molecular rather than elemental information, we have undertaken the siudy of, and have successfully employed crystal diffraction lines as a qualitative and quantitative means for determining such materials as lime, calcium carbonate, road salt, coke dust, and aerosol from sinter emissions as well as several other less common industrial particulates in samples obtained from dustfall as dispersed in a matrix of powdered amorphous glass. Correlative to the above investigation this method was also extended to the study of such gases as sulfur dioxide which may be selectively fixed to an active surface.     

EPA’S Federal Technology Transfer Act Program

In 1986, the Federal Technology Transfer Act (FTTA) was established to promote a closer, collaborative relationship between federal government agencies and the private sector. With the increasing need for new cost-effective technologies to prevent and control pollution, both the U.S. Environmental Protection Agency and private industry are encouraged to facilitate the transfer of knowledge and technology under this Act. The FTTA removed several of the legal and institutional barriers to cooperative research that existed before the Act's passage. Through the FTTA, the government strives to promote the movement of its products, processes, skills and knowledge into the private sector for further development and commercialization by encouraging the exchange of technical personnel and the sharing of facilities and other resources. Collaborative efforts among industry, federal agencies and academia are made possible through cooperative research and development agreements (CRDAs). Thirty-three CRDAs and four licensing agreements have been initiated with EPA under the program. This paper provides an overview of this new and innovative program.     

Estimating Remediation Costs at Contaminated Sites With Varying Amounts of Available Information

Environmental professionals are often tasked with projecting the cost to bring a contaminated site or portfolio of sites to regulatory closure. Fortunately, there are a number of useful guidance documents and industry publications available to assist in such cost projections. However, the usefulness of such tools is limited when adequate costing information is lacking, such as (a) the nature and extent of contamination; (b) regulatory requirements; (c) the remedial approach to be implemented; and/or (d) the duration of operation, maintenance, and monitoring activities. Despite the lack of such information, cost‐to‐closure estimates are nevertheless routinely needed and generated for internal assessments or audits, regulatory disclosures, property acquisitions, insurance claims, litigation, and other business transactions. Cost estimates are also often needed in bankruptcy proceedings where the trier of fact must estimate the total future costs associated with an environmental legacy portfolio to determine the overall value (or solvency in the case of evaluating the potential bankruptcy) of a company. This article presents a solution for developing cleanup costs for single sites or a portfolio of sites using a comprehensive, three‐tiered method that is effective over a wide range of site information. Real‐world examples of the successful application of this method are then provided, based on detailed environmental analyses that were completed for a recent bankruptcy proceeding and a case in which an estimated cleanup cost was needed in a legal proceeding. © 2013 Wiley Periodicals, Inc.     

Toxic effects of oral 2-amino-4,6-dinitrotoluene in the Western fence lizard (Sceloporus occidentalis)

The compound 2-amino-4,6-dinitrotoluene (2A-DNT) was evaluated under laboratory conditions in the Western fence lizard (Sceloporus occidentalis) to assess the potential for reptile toxicity. Oral LD₅₀ values were 1406 and 1867 mg/kg for male and female lizards, respectively. Based on responses from a 14-day subacute study, a 60-day subchronic experiment followed where lizards were orally dosed at 0, 5, 15, 20, 25, 30 mg/kg-d. At day 60, number of days and survivors, food consumption, and change in body weight were inversely related to dose. Signs of toxicity were characterized by anorexia and generalized cachexia. Significant adverse histopathology was observed in hepatic tissue at ≥15 mg/kg-d, consistent with hepatocellular transdifferentiation. Based on survival, loss of body weight, diminished food intake, changes in liver, kidney, and testes, and increased blood urea nitrogen, these data suggest a LOAEL of 15 mg/kg-d and a NOAEL of 5 mg/kg-d in S. occidentalis.