Ecosystem services consideration in the remediation process for contaminated sites.

In 2009, the U.S. Environmental Protection Agency's Science Advisory Board recommended activities to advance consideration of ecosystem services (ES) to enhance existing remediation and redevelopment processes in the U.S. This article examines advancements in the decade since, focusing on providing those involved in cleanup of contaminated sites a basic understanding of ES concepts and guidelines for considering ES at cleanup sites using a new, four-step transferable framework. Descriptions, including activities for site teams and case study applications of ES tools, are presented for each step: (1) identify site-specific ES; (2) quantify relevant ES; (3) examine how cleanup activities affect ES; and (4) identify, select, and implement solutions (e.g., Best Management Practices). The goal of this article is to provide site cleanup stakeholders, including project managers, contractors, and site responsible parties, with a stronger foundation and shared understanding to consider ES during the cleanup process for their given site. Anticipated outcomes include identifying ES benefits to inform management and tradeoff analyses, a reduction in unintended impacts on ES during site operations, and attention to developing a robust suite of ES relevant for site reuse.

On Assessing Risks to Fish Habitats and Populations Associated with a Transportation Corridor for Proposed Mine Operations in a Salmon-rich Watershed.

Natural resource extraction in large undeveloped areas-such as the Bristol Bay watershed in Southwest Alaska-often necessitates construction of roads that contribute substantial environmental risks. Herein, we attempt to address risks from a proposed mine transportation corridor in a virtually roadless watershed that crosses important salmon streams and rivers. The Bristol Bay watershed supports the largest sockeye salmon fishery in the world. A proposed 138 km permanent access road would connect a porphyry copper/gold deposit to a deep-water port. Of 64 potential stream crossings, salmonid spawning migrations may be impeded by culverts at 36 crossings, 32 of which contain restricted upstream habitat. After cessation of mine operations, assuming typical maintenance practices, 10 or more of the 32 streams with restricted upstream habitat would likely be entirely or partly blocked at any time. Consequently, salmon passage-and ultimately production-would be reduced in these streams, and they would likely not be able to support long-term populations of resident species. Additional long-term risks associated with operation of the road include filling or alteration of National Wetland Inventory aquatic habitats; spills of highly toxic xanthate or cyanide due to truck accidents; and reduced habitat quality due to dust production from traffic. We discuss our methodology, and information needs, in the context of Environmental Impact Statements that set the stage for decisions regarding future mining projects.

Evaluation of geochemical associations as a screening tool for identifying anthropogenic trace metal contamination.

Geochemical association plots are used as a screening tool for environmental site assessments and use empirical log-log relationships between total trace metal concentrations and concentrations of a major (i.e., reference) soil metal constituent, such as iron (Fe), to discern sites with naturally elevated trace metal levels from sites with anthropogenic contamination. Log-log relationships have been consistently observed between trace metal and reference metal concentrations and are often considered constant. Consequently, we used a regional geochemistry data set to evaluate background trace metal/Fe log-log associations across soils with highly diverse composition. Our results indicate that, although geochemical associations may be proportional, they significantly differ across predominant United States Department of Agriculture (USDA) soil orders. This suggests that highly complex interactions between soil-forming factors and variable secondary clay mineral composition affect the ratio of trace metals to Fe concentrations in soils. Also, intra-order variability in trace metal/Fe ratios generally ranged multiple orders of magnitude which suggest that the order level of the USDA soil taxonomic system is insufficient to reasonably classify background trace metal concentrations. Consequently, geochemical association plots are a useful screening tool for environmental site assessments, but ubiquitous application of generic background metal data sets could result in erroneous conclusions. Because significantly different ratios were observed across predominant USDA soil orders, an agglomerative clustering technique was used to elucidate hierarchical patterns of association. We present these results as a mechanism to aid environmental assessors in screening candidate background metal data sets for their applicability to site-specific soil composition; although site-specific background metal data should be utilized if ample pristine reference sites with similar (i.e., sub-order) soil composition can be identified and sampled.

Ecological risk assessment issues identified during the U.S. Environmental Protection Agency's examination of risk assessment practices.

Recently, the U.S. Environmental Protection Agency examined its current risk-assessment principles and practices. As part of the examination, aspects of ecological risk-assessment practices were reviewed. Several issues related to ecological risk assessment were identified, including the use of organism-level versus population-level attributes to characterize risk, the possible opportunities associated with the increased use of probabilistic approaches for ecological risk assessment, and the notion of conservatism in estimating risks. The agency examination provides an understanding of current practices and is intended to begin a dialogue in which the risk assessment community can engage in addressing the identified issues to improve and enhance ecological risk assessment.