Ihor Hlohowskyj

Toxicity Bioassays for Ecological Risk Assessment in Arid and Semiarid Ecosystems

Substantial tracts of land in the southwestern and western U.S. are undergoing or will require ERA. Toxicity bioassays employed in baseline ERAs are, for the most part. representative of mesic systems, and highly standardized test species (e.g., lettuce, earthworm) are generally not relevant to arid system toxicity testing. Conversely, relevant test species are often poorly characterized with regard to toxicant sensitivity and culture conditions. The applicability of toxicity bioassays to ecological risk assessment in arid and semiarid ecosystems was reviewed for bacteria and fungi, plants, terrestrial invertebrates, and terrestrial vertebrates. Bacteria and fungi are critical to soil processes, and understanding their ecology is important to understanding the ecological relevance of bioassays targeting either group. Terrestrial bacteria require a water film around soil particles to be active, while soil fungi can remain active in extremely dry soils. It is therefore expected that fungi will be of greater importance to arid and semiarid systems (Whitford 1989). If microbial processes are to be measured in soils of arid environments, it is recommended that bioassays target fungi. Regardless of the taxa studied, problems are associated with the standardization and interpretability of microbial tests, and regulatory acceptance may hinder widespread incorporation of microbial toxicity bioassays in arid system risk assessments. Plant toxicity bioassays are gaining recognition as sensitive indicators of soil conditions because they can provide a cost-effective and relatively rapid assessment of soil quality for both pre- and postremediation efforts. Phytotoxicity evaluations commonly target germination because environmental stressors have the greatest potential for exerting adverse effects in the early stages of growth. In arid systems, seeds respond rapidly to precipitation events, and it is typically after germination has occurred that plants must cope with water stress. Consequently, seedling emergence studies should be conducted under nonlimiting moisture conditions characteristic of mesic plant testing. Further ecological realism can be incorporated into advanced growth stages by creating moisture conditions representative of the arid system study site. Although the choices of suitable plant species for assessing mesic system soils are numerous, the choices for arid system soils are limited. Guidance is provided for evaluating plant species with regard to their suitability for serving as representative arid system flora. Terrestrial invertebrates can survive and flourish in extremely dry conditions. They play key roles in ecosystem functioning in arid environments. Perhaps the biggest drawback to using terrestrial invertebrates for toxicity bioassays involves uncertainties associated with choosing appropriate test species. Several examples of standard species exist for mesic soils (e.g., the earthworm Eisenia foetida and the collembolan Folsomia candida), whereas no analogous organisms are available for testing arid and semiarid soils. The aid of an expert taxonomist and some basic research are prerequisite to using ecologically relevant invertebrates. The use of birds for ecotoxicity testing in arid and semiarid environments is not recommended. On the other hand, mammals, especially rodents, are well represented in arid ecosystems. Much of the ecotoxicity testing performed on rodents is generally applicable to arid-adapted species; few demonstrations of rodent ecotoxicity testing for dry environments exist. Relative to other organisms discussed, such as soil invertebrates, the use of mammals in toxicity bioassays faces several obstacles. Terrestrial plants and soil invertebrates appear to be the most appropriate and feasible organisms for ecotoxicity testing in arid and semiarid environments. Potentially relevant test species for arid system testing are often poorly characterized with regard to toxicant sensitivity and culture conditions. Table 6 presents examples of standard and nonstandard species with these considerations in mind, and the best estimate of regulatory acceptance for each of the organisms is suggested. If currently accepted bioassays are not appropriate for evaluating risks in arid and semiarid ecosystems, their use in conducting ERAs in such environments may result in inadequate expenditure of time and money to develop data that accurately characterize risks. The inapplicability of this technical tool will thus hamper the risk management decision-making process and result in flawed decisions.

Reduction in tolerance to progressive hypoxia in the central stoneroller minnow following sublethal exposure to phenol

Acute exposure of the central stoneroller minnow to sublethal levels of phenol was found to decrease the ability of this species to tolerate hypoxic conditions as indicated by the dissolved oxygen (DO) concentration at which loss of equilibrium occurred. For fishes acclimated at 7.5 °C, loss of equilibrium occurred at progressively higher DO levels as the phenol exposure concentration was increased from 0 to 12 mg phenol L−1. Mean DO concentrations at which loss of equilibrium occurred ranged from 2.33 ± 0.10 mg O2 L−1. for the control group (0 mg phenol L−1. to 2.76 ± 0.14 mg O2 L−1. (at 12 mg phenol L−1. Loss of equilibrium also occurred at progressively higher DO levels in fish acclimated at 23 °C, but only after an initial decrease among the 6 mg phenol L−1. test fish in the loss of equilibrium DO concentration. At 23 °C, loss of equilibrium occurred at DO levels ranging from 1.3 ± 0.09 mg O2 L−1. (6 mg phenol L−1. to 2.33 ± 0.16 mg O2 L−1. (12 mg phenol L−1. These data indicate that acute exposures to sublethal levels of phenol can have significant effects on the ability of the stoneroller minnow to tolerate conditions of low DO, and the results agree with the previously reported relationship between phenol toxicity and DO levels.

Aquatic Nuisance Species in the Great Lakes and Mississippi River Basin—A Risk Assessment in Support of GLMRIS

The U.S. Army Corps of Engineers is conducting the Great Lakes and Mississippi River Interbasin Study to identify the highest risk aquatic nuisance species currently established in either the Mississippi River Basin or the Great Lakes Basin and prevent their movement into a new basin. The Great Lakes and Mississippi River Interbasin Study focuses specifically on aquatic nuisance species movement through the Chicago Area Waterway System, a multi-use waterway connecting the two basins. In support of Great Lakes and Mississippi River Interbasin Study, we conducted a qualitative risk assessment for 33 aquatic nuisance species over a 50-year period of analysis based on the probability of aquatic nuisance species establishing in a new basin and the environmental, economic, and sociopolitical consequences of their establishment. Probability of establishment and consequences of establishment were assigned qualitative ratings of high, medium, or low after considering the species’ current location, mobility, habitat suitability, and impacts in previously invaded systems. The establishment and consequence ratings were then combined into an overall risk rating. Seven species were characterized as posing a medium risk and two species as posing a high risk to the Mississippi River Basin. Three species were characterized as posing a medium risk to the Great Lakes Basin, but no high-risk species were identified for this basin. Risk increased over time for some aquatic nuisance species based on the time frame in which these species were considered likely to establish in the new basin. Both species traits and the need to balance multiple uses of the Chicago Area Waterway System must be considered when identifying control measures to prevent aquatic nuisance species movement between the two basins.

Remedial investigation report for J-Field, Aberdeen Proving Ground, Maryland. Volume 3: Ecological risk assessment

The Environmental Management Division of the U.S. Army Aberdeen Proving Ground (APG), Maryland, is conducting a remedial investigation (RI) and feasibility study (FS) of the J-Field area at APG, pursuant to the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), as amended. As part of that activity, Argonne National Laboratory (ANL) conducted an ecological risk assessment (ERA) of the J-Field site. This report presents the results of that assessment.

Ecological risk assessment of radiological exposure to depleted uranium in soils at a weapons testing facility.

The potential for unacceptable risks to biota from radiological exposure to depleted uranium (DU) in soils was evaluated at two sites where DU weapons testing had been conducted in the past. A screening risk assessment was conducted to determine if measured concentrations of DU-associated radionuclides in site soils exceed radionuclide levels considered protective of biota. While concentrations of individual radionuclides did not exceed acceptable levels, total radionuclide concentrations could result in potentially unacceptable doses to exposed biota. Thus, a receptor-specific assessment was conducted to estimate external and internal radiological doses to vegetation and wildlife known or expected to occur at the sites. Wildlife evaluated included herbivores, omnivores, and top-level predators. Internal dose estimates to wildlife considered exposure via fugitive dust inhalation and soil and food ingestion; root uptake was the primary exposure route evaluated for vegetation. Total doses were compared with acceptable dose levels of 1.0 and 0.1 rad/day for vegetation and wildlife, respectively, with potentially unacceptable risks indicated for doses exceeding these levels. All estimated doses were below or approximated acceptable levels, typically by an order of magnitude or more. These results indicate that current levels of DU in soils do not pose unacceptable radiological risks to biota at the sites evaluated.

Examining the Potential for Agricultural Benefits from Pollinator Habitat at Solar Facilities in the United States

Of the many roles insects serve for ecosystem function, pollination is possibly the most important service directly linked to human well-being. However, land use changes have contributed to the decline of pollinators and their habitats. In agricultural landscapes that also support renewable energy developments such as utility-scale solar energy [USSE] facilities, opportunities may exist to conserve insect pollinators and locally restore their ecosystem services through the implementation of vegetation management approaches that aim to provide and maintain pollinator habitat at USSE facilities. As a first step toward understanding the potential agricultural benefits of solar-pollinator habitat, we identified areas of overlap between USSE facilities and surrounding pollinator-dependent crop types in the United States (U.S.). Using spatial data on solar energy developments and crop types across the U.S., and assuming a pollinator foraging distance of 1.5 km, we identified over 3,500 km2 of agricultural land near existing and planned USSE facilities that may benefit from increased pollination services through the creation of pollinator habitat at the USSE facilities. The following five pollinator-dependent crop types accounted for over 90% of the agriculture near USSE facilities, and these could benefit most from the creation of pollinator habitat at existing and planned USSE facilities: soybeans, alfalfa, cotton, almonds, and citrus. We discuss how our results may be used to understand potential agro-economic implications of solar-pollinator habitat. Our results show that ecosystem service restoration through the creation of pollinator habitat could improve the sustainability of large-scale renewable energy developments in agricultural landscapes.

Methods for Vulnerability and Adaptation Assessment

The 55 countries participating in the U.S. Country Studies Program are using a variety of methods to assess their vulnerability to climate change and the potential for implementing adaptation options. Many of the countries are using models and methodologies provided by the U.S. Country Studies while others are using other methods and methodologies (Table 2.1). In all cases the countries are adapting the models and methodologies to their unique national circumstances. This chapter briefly describes those models and methodologies made available by the U.S. Country Studies Program. Readers will not find these models and methodologies described elsewhere in this report.

A survey of the wetlands and floodplains of the borrow area and wetland/shorebird complex for the remedial action at the chemical plant area of the Weldon Spring Site

The US Department of Energy is conducting cleanup operations at the Weldon Spring site, St. Charles, Missouri, that will include development of a 77-ha (191-acre) soil borrow area. Eight wetlands, including riverine and palustrine emergent wetland types and totaling 0.9 ha (2.2 acres), will be eliminated during excavation of the borrow area. A 23-ha (57-acre) wetland/shorebird complex will be created at the Busch Conservation Area. The complex will include 2 ha (5 acres) of palustrine emergent wetland as mitigation for wetland losses in the borrow area.