a-flow-through-exposure-system-for-evaluating-suspended-sediments

A Flow-through Exposure System for Evaluating Suspended Sediments Effects on Aquatic Life

This paper describes the Fish Larvae and Egg Exposure System (FLEES). The flow-through exposure system is used to investigate the effects of suspended ...

U.S. Army Corps of Engineers

When evaluating the risk chemicals may pose to mammals and birds in ecological risk assessments (ERAs), it is common practice to conservatively assume that all (100%) of a chemical in an environmental medium is bioavailable to receptors. This assumption often leads to overestimating ecological risk and may ultimately result in costly and unnecessary risk management actions. While effects of bioavailability and speciation of metals such as arsenic (As) and lead (Pb) have been considered in human health risk assessment, these effects are rarely taken into consideration when assessing risks to mammals and birds. An ERA was conducted at the former Col-Tex refinery site in Colorado City, Texas, USA, to characterize risks to select wildlife species from exposure to chromium (Cr) and Pb found in soils. The focus on these metals was based on results of a screening-level ERA that found that Cr and Pb were posing ecological risks at the site. Soils were analyzed for total Cr and Pb, trivalent Cr (CrIII), hexavalent Cr (CrVI), organic Pb, and the bioavailability and speciation of Pb. Results for Pb and Cr indicated that >94% of the Cr was present as the less toxic and immobile Cr(III) and that >99% of the Pb in soils was present as inorganic Pb. Lead bioaccessibility measured by in vitro testing ranged from 8% to 77.8%, depending on location of individual soil samples. Results demonstrated that Pb and Cr bioavailability and speciation information can raise soil cleanup concentrations while being protective of ecological receptors. The costs of performing the ERA were de minimus compared to the reduction in remediation costs at the site. The refined hazard estimates allowed informed decision making in the management and segregation of soils, allowing for effective risk management at the site.

The value of metals bioavailability and speciation information for ecological risk assessment in arid soils.

The spread of nonindigenous (nonnative) species introduced into the United States is a significant and growing national problem and results in lost agricultural productivity, increased health problems, native species extinctions, and expensive prevention and eradication efforts. Thousands of nonindigenous species have either become established or spread, and introduction of aquatic nuisance species (ANS) into freshwater lakes threaten aquatic biodiversity. Expanding global trade is likely to increase the number of species that are spread across the globe, so the need to develop an approach to predict potential ANS invasions is great. Risk assessments currently being used to assess ANS risk rely on qualitative or semiquantitative information and expert opinion; thus, such approaches lack transparency and repeatability. A more quantitative approach is needed to augment the qualitative approaches currently in use. A quantitative approach with the use of the traditional ecological risk assessment (traditional ERA) framework combined with decision analysis tools was developed for assessing ANS risks in which the causative ecological risk agent is an organism rather than a chemical. This paper presents a systematic risk assessment framework that includes structured decision analysis to help organize and analyze pertinent data, state assumptions, address uncertainties in estimating the probability of an undesired ANS introduction, or spread and integrate these outputs with stakeholder values. This paper also describes when and how decision analysis tools can be used in such assessments for ANS. This framework and methodology will enable risk managers to systematically evaluate and compare alternatives and actions supporting ANS risk management and thus credibly prioritize resources.

Application of risk assessment and decision analysis to aquatic nuisance species.

The U.S. Army Engineer Research and Development Center Environmental Laboratory, Vicksburg, MS, conducted a study to determine the extent to which Hurricane Katrina floodwaters in the New Orleans, Louisiana area may have had impacts on wildlife habitat and other biological resources in surrounding areas. These studies were conducted as part of the Interagency Performance Evaluation Taskforce, an investigation of environmental impacts originating from the failure of the hurricane protection system during Hurricane Katrina. This paper presents data regarding the effects of pumped floodwaters on sediment chemistry, toxicity, and benthic invertebrate assemblages near pumping stations that discharged floodwaters into marshes near Chalmette and Violet, Louisiana. Chemical contamination of sediments was observed and varied among sample locations (e.g., outfall locations, wastewater treatment plant, canals, and wetlands); however, trends in the chemistry data were not always consistent with bioassay results. A comparison of the sediment chemistry data from this study with three other studies reporting concentrations of chemicals in sediments within the city of New Orleans suggested that sediments and associated contaminants present within the levees were not pumped into the marsh in appreciable quantities.

Environmental consequences of water pumped from greater New Orleans following Hurricane Katrina: chemical, toxicological, and infaunal analysis.

Sediment dredging is necessary to sustain navigation infrastructure in ports and harbor areas. In the United States alone between 250 and 300 million cubic yards of sediment are dredged annually. Dredging activities may cause stress on aquatic biota by locally increasing turbidity and suspended sediment concentrations, physically disturbing habitat by elevated sedimentation rates, interfering in migratory behaviors, and hydraulically entraining bottom dwelling organisms. Environmental windows are a management practice used to alleviate such stresses on resident and transient biota by placing temporal restrictions on the conduct of dredging operations. Adherence to environmental windows can significantly inflate costs for project sponsors and local stakeholders. Since their inception following passage of NEPA in 1969 the process for setting environmental windows has not followed structured procedures and represents an example of the difficulty inherent in achieving a balance between biological resource protection and cost-effective construction and maintenance of navigation infrastructure. Recent developments in the fields of risk assessment for non-chemical stressors as well as experience in implementing structured risk-informed decision-making tools for sediment and natural resource management are summarized in this paper in relation to setting environmental windows. Combining risk assessment and multi-criteria decision analysis allows development of a framework for an objective process consistent with recommendations by the National Academy of Sciences for setting environmental windows. A hypothetical application of the framework for protection of Pacific herring (Clupea pallasii) in San Francisco Bay is discussed.

A risk-informed decision framework for setting environmental windows for dredging projects.

During the last four years, significant effort has been devoted to understanding the effects that Hurricanes Katrina and Rita had on contaminant distribution and redistribution in New Orleans, Louisiana, USA, and the surrounding Gulf Coast area. Elevated concentrations were found for inorganic contaminants (including As, Fe, Pb, and V), several organic pollutants (polycyclic aromatic hydrocarbons, pesticides, and volatiles) and high concentration of bioaerosols, particularly Aeromonas and Vibrio. Data from different research groups confirm that some contaminant concentrations are elevated, that existing concentrations are similar to historical data, and that contaminants such as Pb and As may pose human health risks. Two data sets have been compiled in this article to serve as the foundation for preliminary risk assessments within greater New Orleans. Research from the present study suggests that children in highly contaminated areas of New Orleans may experience Pb exposure from soil ranging from 1.37 microg/d to 102 microg/d. These data are critical in the evaluation of children's health.

Lead distributions and risks in New Orleans following Hurricanes Katrina and Rita.

Many years of untreated effluent discharge from residential areas, a shipyard, a marina, and a large fish market resulted in substantial contamination of bottom sediment in Southern Busan Harbor, South Korea. Contaminants in these sediments include heavy metals and organic compounds. Newly introduced regulations for ocean disposal of dredged material in South Korea pose significant challenges, because the previous practice of offshore disposal of contaminated dredged material was no longer possible after August 2008. The South Korean government has mandated that such sediments be assessed in a way that identifies the most appropriate dredged material management alternative, addressing environmental, social, and cost objectives. An approach using multicriteria decision analysis (MCDA) in combination with comparative risk assessment was used as a systematic and transparent framework for prioritizing several dredged sediment management alternatives. We illustrate how MCDA can recognize the multiple goals of contaminated sediment management. Values used in weighting decision criteria were derived from surveys of stakeholders who were sediment management professionals, business owners, or government decision makers. The results of the analysis showed that land reclamation was the preferred alternative among cement-lock, sediment washing, 3 contained aquatic disposal alternatives (one in combination with a hopper dredge), geotextile tubes, solidification, and land reclamation after solidification treatment. Land reclamation was the preferred alternative, which performed well across all MCDA objectives, because of the availability of a near-shore confined disposal facility within a reasonable distance from the dredging area.

Multicriteria decision analysis to assess options for managing contaminated sediments: Application to Southern Busan Harbor, South Korea.

To meet London Protocol requirements, South Korea is preparing to reduce the need for disposal of dredged material at sea. The new requirements controlling ocean disposal of dredged material pose significant challenges to the South Korean government, because the previous practice of offshore disposal of contaminated dredged material is no longer permitted. Hence, other alternatives for treating and disposing of contaminated dredged material are being evaluated and selected for implementation. A new management and decision approach is therefore needed for regulators and implementers to show what information and what decision-making processes were used to make the decision, to increase administrative transparency for such projects in the public domain. To address this need, an iterative approach was developed for dredged material management that includes the essential elements of process, people, and tools needed for successful environmental decision making. The approach has 6 steps: problem definition, developing objectives and criteria, identifying alternatives, performing the evaluation, comparing alternatives, and selecting the preferred alternative. The primary objective of the approach is to provide a systematic means of exploring contaminated dredged material management alternatives in South Korea using criteria that integrate risk with economic and stakeholder value information. The approach incorporates the desired decision-making attributes of transparency, comparative analysis, and inclusion of public input. Although it was developed for South Korea, the approach can be applied in any situation in which dredged material management alternatives are being considered to manage contaminated sediment risks.

A decision-analysis approach for contaminated dredged material management in South Korea.

Navigation infrastructure such as channels, jetties, river training structures, and lock-and-dam facilities are primary components of a safe and efficient water transportation system. Planning for such infrastructure has until recently involved efforts to minimize impacts on the environment through a standardized environmental assessment process. More recently, consistent with environmental sustainability concepts, planners have begun to consider how such projects can also be constructed with environmental enhancements. This study examined the existing institutional conditions within the US Army Corps of Engineers and cooperating federal agencies relative to incorporating environmental enhancements into navigation infrastructure projects. The study sought to (1) investigate institutional attitudes towards the environmental enhancement of navigation infrastructure (EENI) concept, (2) identify potential impediments to implementation and solutions to such impediments, (3) identify existing navigation projects designed with the express intent of enhancing environmental benefit in addition to the primary project purpose, (4) identify innovative ideas for increasing environmental benefits for navigation projects, (5) identify needs for additional technical information or research, and (6) identify laws, regulations, and policies that both support and hinder such design features. The principal investigation tool was an Internet-based survey with 53 questions. The survey captured a wide range of perspectives on the EENI concept including ideas, concerns, research needs, and relevant laws and policies. Study recommendations included further promotion of the concept of EENI to planners and designers, documentation of existing projects, initiation of pilot studies on some of the innovative ideas provided through the survey, and development of national goals and interagency agreements to facilitate implementation.

Environmental engineering of navigation infrastructure: a survey of existing practices, challenges, and potential opportunities.

Chemical bioavailability is an important dose metric in environmental risk assessment. Although many approaches have been used to evaluate bioavailability, not a single approach is free from limitations. Previously, we developed a new genomics-based approach that integrated microarray technology and regression modeling for predicting bioavailability (tissue residue) of explosives compounds in exposed earthworms. In the present study, we further compared 18 different regression models and performed variable selection simultaneously with parameter estimation.

Predicting chemical bioavailability using microarray gene expression data and regression modeling: A tale of three explosive compounds.

The resuspension of sediments caused by activities, such as dredging operations, is a concern in Great Lakes harbors where multiple fish species spawn. To address such concerns, smallmouth bass (Micropterus dolomieu) were exposed to uncontaminated suspended sediment (nominally 0, 100, 250, and 500 mg/L) continuously for 72 h to determine the effects on egg-hatching success and swim-up fry survival and growth. The test sediments were collected from two harbors: (1) fine-grained sediment in Grand Haven Harbor, Lake Michigan, and (2) coarser-grained sediment in Fairport Harbor, Lake Erie. Eggs exposed to total suspended solids (TSS) concentrations >100 mg/L resulted in decreased survival of post-hatch larval fish. Fry survival was >90 % at the highest exposure concentration (500 mg/L), but growth was decreased when the exposure concentration was >100 mg/L. Growth and survival of swim-up fry held for a 7- and 26-day post-exposure the grow-out period was variable suggesting that the sediment grain size and strain of fish may influence lingering effects after the cessation of exposure. The results suggest that exposed eggs hatched normally; however, newly hatched larvae, which are temporarily immobile, are more vulnerable to the effects of suspended sediment. The swim-up fry were found to be more sensitive to high TSS concentrations in sandy relative to silty sediment. These data represent a conservative exposure scenario that can be extrapolated to high-energy systems in the field to inform management decisions regarding the necessity for dredging windows or need to implement controls to protect M. dolomieu.

Burton C. Suedel

Environmental Laboratory,
Engineer Research and Development Center,
Environmental Laboratory, Engineer Research and Development Center

U.S. Army Corps of Engineers

A Flow-through Exposure System for Evaluating Suspended Sediments Effects on Aquatic Life

Burton C. Suedel

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Environmental Laboratory,Engineer Research and Development Center,Environmental Laboratory, Engineer Research and Development Center

U.S. Army Corps of Engineers

A Flow-through Exposure System for Evaluating Suspended Sediments Effects on Aquatic Life

Environmental Laboratory,
Engineer Research and Development Center,
Environmental Laboratory, Engineer Research and Development Center