An ecological significance framework is used to assess the ecological condition of Prince William Sound (PWS), Alaska, USA, in order to address the current management question: 17 y following the Exxon Valdez oil spill (EVOS), are there any remaining and continuing ecologically significant exposures or effects on the PWS ecosystem caused by EVOS? We examined the extensive scientific literature funded by the Exxon Valdez Trustees or by ExxonMobil to assess exposures and effects from EVOS. Criteria to assess ecological significance include whether a change in a valued ecosystem component (VEC) is sufficient to affect the structure, function, and/or health of the system and whether such a change exceeds natural variability. The EVOS occurred on 24 March 1989, releasing over 250,000 barrels of crude oil into PWS. Because PWS is highly dynamic, the residual oil was largely eliminated in the first few years, and now only widely dispersed, highly weathered, or isolated small pockets of residual contamination remain. Many other sources of polycyclic aromatic hydrocarbons (PAHs) exist in PWS from past or present human activities or natural oil seeps. Multiple-lines-of-evidence analyses indicate that residual PAHs from EVOS no longer represent an ecologically significant exposure risk to PWS. To assess the ecological significance of any residual effects from EVOS, we examined the literature on more than 20 VECs, including primary producers, filter feeders, fish and bird primary consumers, fish and bird top predators, a bird scavenger, mammalian primary consumers and top predators, biotic communities, ecosystem-level properties of trophodynamics and biogeochemical processes, and landscape-level properties of habitat mosaic and wilderness quality. None of these has any ecologically significant effects that are detectable at present, with the exception of 1 pod of orcas and possibly 1 subpopulation of sea otters; however, in both those cases, PWS-wide populations appear to have fully recovered. Many other stressors continue to affect PWS adversely, including climate and oceanographic variability, increased tourism and shipping, invasive species, the 1964 earthquake, and overexploitation of marine resources, with associated cascading effects on populations of PWS fish and predators. We conclude that the PWS ecosystem has now effectively recovered from EVOS.

Residence times are defined classically by the physical and chemical aspects of water bodies rather than by their ecological implications. Therefore, a more clear and direct connection between the residence times and ecological effects is necessary to relate these timescales quantitatively to ecology. The concept of local effect time (LET) is proposed in this paper as a timescale with spatial resolution that relates to ecological components and their spatial distribution within an embayment. The LET can predict the susceptibility of real-world ecological components to change from one condition to another. It can provide an efficient way to allow managers and agencies to evaluate the degree of stress or relief from current or projected changes in the loading of contaminants or nutrients. The steps for calculating LETs and defining their correlation with the existing ecological components in an embayment are presented along with illustrative applications to loading from riverine inflow and a wastewater treatment plant. The LET successfully identified the areas within the water body that could be prone to ecological changes due to perturbations in the loading rate of riverine water and its constituents. An example is given that shows how the LET method can be used to delineate the distribution and duration of high levels of coliform bacteria due to a pulsed effluent from the treatment plant.

Redevelopment of landfill sites in the New Jersey–New York metropolitan area for recreational (golf courses), commercial, and even residential purposes seems to be gaining acceptance among municipal planners and developers. Landfill gas generation, which includes methane and potentially toxic nonmethane compounds usually continues long after closure of the landfill exercise phase. It is therefore prudent to evaluate potential health risks associated with exposure to gas emissions before redevelopment of the landfill sites as recreational, commercial, and, especially, residential properties. Unacceptably high health risks would call for risk management measures such as limiting the development to commercial/recreational rather than residential uses, stringent gas control mechanisms, interior air filtration, etc. A methodology is presented for applying existing models to estimate residual landfill hazardous compounds emissions and to quantify associated health risks. Besides the toxic gas constituents of landfill emissions, other risk-related issues concerning buried waste, landfill leachate, and explosive gases were qualitatively evaluated. Five contiguously located landfill sites in New Jersey intended for residential and recreational redevelopment were used to exemplify the approach.

Sediment trend analysis (STA) is a technique that determines the net patterns of sediment movement and their dynamic behavior or stability. The data required are the complete particle size distributions obtained from bottom grab samples collected in a regular grid over the area of interest.  Appendix 1 provides the particular details of how STA is undertaken. Because many contaminants are known to associate with the natural particles contained in sedimentary deposits, STA can provide additional weight-of-evidence in ecological risk assessment, remedial investigation, remediation itself, and litigation issues. The STA was applied to 242 sediment samples collected from the Hylebos Waterway, Tacoma, Washington, USA, in support of remedial action planning, contaminant source identification, and ultimately allocation of legal liability for contamination. The Waterway itself comprises a narrow shipping channel extending 3 miles from Commencement Bay (Puget Sound) where it ends in a dredged turning basin (Upper Turning Basin). A 2nd dredged turning basin (Lower Turning Basin) is located about three-quarters of the distance down its length. Both sides of the channel are home to an extensive industrial complex associated with significant contaminant releases into the water. The area was declared a Superfund Site in the early 1980s.The results of the STA showed a consistent pattern of sediment transport directed from the mouth of the Waterway to the turning basin at its head. Divided into 5 separate transport environments (TEs), the sediments within the Waterway progress from transport in Dynamic Equilibrium near the mouth, to Total Deposition (type 1) in the vicinity of the Lower Turning Basin, followed by Total Deposition (type 2) in the Upper Turning Basin. Assuming that contaminants associate preferentially with the finer, rather than the coarser, components of the grain size distributions, a probable behavior of contaminants that can be contained in the sediments is proposed for each TE. Maps showing the spatial distributions of existing contaminant data appear to conform very well to the patterns that might be expected from the STA results. This evidence was primarily used to demonstrate that potentially responsible parties (PRPs) located at the head of the Waterway could not be responsible for contaminated sediments toward its mouth. The findings, for example, effectively dismissed the assumption by the Natural Resource Damage Trustee agencies that contaminated sediments from a particular source would be as likely to migrate down the Waterway as up the Waterway. As a result, major documented sources of contamination near the mouth should be expected to bear a larger share of the total cleanup compared with sources farther toward the head. Furthermore, the STA provided explanations for apparent anomalies such as how hot spots of polychlorinated biphenyls (PCBs) could be located near a property where PCBs had never been released into the environment. If sediment gradient pattern analysis alone were used to allocate liability among PRPs, those located near such hot spots would receive a disproportionate share of liability.

A methodology for selecting remediation technologies is presented as part of a decision support system for the rehabilitation of contaminated sites. It includes 2 steps: In the 1st step, a pool of suitable technologies is selected within a technologies database according to their applicability to site-specific conditions; in the 2nd step, the selected technologies are ranked according to a multicriteria decision analysis (MCDA) approach. The MCDA was applied to allow for a transparent procedure and for the integration of expert analyses. The methodology was implemented in a previously developed georeferenced information system–based decision support system for the rehabilitation of contaminated sites and then applied to a case study (Porto Marghera, Venice, Italy). On the basis of the obtained results, the proposed methodology appeared suitable to select remediation technologies according to both technical features and requirements of available technologies, as well as site-specific environmental conditions of the site of concern, such as chemical contamination levels and remediation objectives.

This study examined the possibility of using striped field mice as a biological dosimeter or indicator for surveillance of the ecological effects of boundary radiation emitted by nuclear power plants. For this study, the external morphological characteristics and isoenzymic electrophoretypes of Korean domestic dark-striped field mice were studied after they were captured, controlled for reproduction, and their exact species were identified. In terms of morphological external characteristics, the dark-brown coat, dark back stripe, head-to-tail length, tail length, and ear length matched the taxonomical characteristics of dark-striped field mice. In terms of isoenzymic electrophoretypes, the analyses on l-lactate dehydrogenase, aspartate aminotransferase, and malate dehydrogenase revealed that one species of dark-striped field mice, called Apodemus agrarius coreae, was scattered throughout a wide range of habitats. On the other hand, after irradiating the A. a. coreae (0, 0.5, 1, 3, 5, and 7 gray [Gy]) to analyze their survival rate and frequency of micronuclei in peripheral polychromatic erythrocytes, their LD50/30 was approximately 5 Gy. Also, the mice that contained 1 or 3 Gy gained weight compared with those that contained 0.5 Gy. Moreover, those with 0.5 Gy and higher showed an increase in white blood cells and platelets as well as in sodium and creatinine. However, decreased concentrations of alkaline phosphatase, alanine animotransferase, calcium, phosphorus, and globulin were observed in the A. a. coreae after irradiation. The results of the study reveal that wild A. a. coreae mice have high potential as a biological monitoring system to determine radiation effects in human environments such as those within the vicinity of nuclear power plants.

The term “nanomaterial” describes a preparation in which the particle size is on the order of 10 to 100 nm in diameter. Such particles have the ability to form suspensions in fluid media such as air and water that can dramatically increase the environmental transport potential in comparision with like materials of larger particle sizes. Quantifying such transport requires an ability to predict the stability of such suspensions as to their tendency to aggregate or interact with other environmental constituents. In this paper, we present a method for predicting the magnitude and uncertainty associated with nanoparticle suspension stability. The critical buoyancy properties are predicted using the Boltzmann equation. The rates of aggregation are then predicted on the basis of molecular collision and adhesion coefficients. The progress of particle growth is simulated across all potential pathways probabalistically using the Gillespie model to characterize the uncertainty. Discussion is provided regarding potential environmental applications and further potential development in predicting particle behavior and effects on the environment.