Risk-Cost Trade Off Considerations for Contaminated Sediment Disposal

Delays in dredging and inability to dredge the nation's harbors, due to the presence of contaminated sediments and the lack of environmentally acceptable disposal sites are interfering with shipping activities and hampering trade growth. The United States Government is committed to provide continuing support to the port industry's goals for enhancing economic growth while protecting, conserving and restoring natural resources within coastal aquatic lands. The government's commitment has resulted in the articulation of a national dredging policy in the Action Plan for Improvement of the Dredging Process in the United States. This national challenge calls for a systematic and consistent decision making approach to dredging and disposal including contaminated sediment management. In building an effective decision mak ing framework for costs, risk reduction and potential beneficial uses of the disposal material must be considered in identifying and evaluating environmentally acceptable and cost-effective disposal alternatives. A conceptual framework for applying a risk-cost trade off approach in making decisions regarding contaminated sediment disposal is presented and applied to a hypothetical disposal scenario involving three alternatives: deepwater confined disposal, nearshore fill or capping and, upland disposal. The approach entails the performance of sequential evaluations consisting of risk analysis, estimation of costs, integration of the results into a computational framework for trade-off analysis, and the application of decision analytical tools to build consensus among stakeholders and the general public in selecting a preferred alternative.     

United States legislation and the polar oceans

The United States has important national interests vested in both the Arctic and Antarctic Oceans. Thus, in recent decades the United States has progressively codified its national commitment to conserve and manage both these marine regions and their resources and to protect them from activities that might produce adverse impacts. The U.S. legislation passed since the 1960s selectively affects both polar regions and supports major American policy objectives there: to maintain the Arctic and Antarctic as areas of international cooperation for peaceful purposes; to satisfy economic needs, especially hydrocarbon, mineral, and living resources; to protect opportunities for scientific research; to protect the marine environment; and to conserve living resources in the circumpolar seas. Future trends suggest a shift in U.S. policy attention to the Arctic. Accordingly, new U.S. legislation will be needed to regulate increased activities in the polar north.     

Estimation of Sediment Ingestion Rates Based on Hand-to-Mouth Contact and Incidental Surface Water Ingestion

There is a lack of scientifically justified approaches for assessing sediment ingestion rates of people exposed to contaminated sediments. Consequently, a method was developed to estimate sediment ingestion rates from: (1) hand-to-mouth contact with sediments and (2) incidental ingestion of surface water containing suspended sediments. In the case of hand-to-mouth contact, a mechanistic approach was used based on established principles and assumptions previously used for estimation of soil and dust ingestion rates. A key modification of the approach was to account for greater adherence of sediments to hands as compared to soil and dusts. For estimation of sediment ingestion from surface water contact, a method was developed that considered the unique aspects of suspended sediments. The analysis indicated that hand-to-mouth contact is the dominant pathway for ingestion of sediment. When people use aquatic areas for recreational purposes, the analysis has indicated that mean sediment ingestion rates may range from 18 to 72 mg/h for various receptor age groups. For sites where people spend more than 1 h per day on a consistent basis in direct contact with sediments, the results indicate that sediment ingestion rates may be greater than those typically assumed in Canadian human health risk assessment guidance for soils.     

The Management of Contaminated Sediment in Hong Kong

Many years of uncontrolled discharge of sewage and industrial effluent have resulted in serious contamination of much of the sediments underlying inland and nearshore coastal waters in Hong Kong by potentially toxic heavy metal and trace organic pollutants. Much has been achieved to improve control of this pollution at the source and prevent further deterioration. Nevertheless, comprehensive environmental assessment and management measures are required to ensure that any unacceptably contaminated sediment that must be dredged to facilitate infrastructural development is safely handled and disposed of. It is estimated that some 50?Mm³ of sediment classified as unacceptably contaminated may require dredging and special management elsewhere over the coming 10-year period. To facilitate improved decision making about the most appropriate disposal options for dredged sediment Hong Kong has recently implemented a new sediment quality assessment framework under which information on the biological activity of contaminated material is considered in addition to data on chemical composition. Dredged sediment classified as unacceptably contaminated has been disposed of at a contained disposal facility at East Sha Chau since 1992. To date over 20?Mm³ of sediment has been placed into seabed pits that are subsequently capped with clay. The site is subject to a rigorous monitoring programme that has clearly demonstrated its environmental acceptability.     

The Origin of the USDA Regional Biomass Research Centers

The U.S. Department of Agriculture (USDA) Regional Biomass Research Centers (RBRC) were created to contribute to the planning, research, and development of entire long-term sustainable biofuel production supply chains based on agricultural and forest-based feedstocks. The intent of the centers is to provide a catalyst that links feedstock genetic development, sustainable production and management, logistics, conversion, co-product production, distribution, and market demand suited to the available economic, social, and natural resources within different regions. The centers provide a coordinated, region-based research focus designed with relatively short-term deliverables to help accelerate the commercial production of biomass and other biofuel feedstocks. The centers provide a leadership structure for coordinating biomass research across the country, providing a national perspective that complements other USDA agency efforts designed to help US rural communities participate in the emerging biofuels and biobased products economy. Through coordination with the RBRC, USDA research and service agency programs and resources have been leveraged with the U.S. Department of Energy (DOE) and other federal department, university, and private industry efforts to help accelerate commercial advancement of advanced biofuel production to promote rural economic opportunities and achieve transportation biofuel policy goals.     

Influences on copper bioaccumulation,growth, and survival of the midge,Chironomus tentans,in metal-contaminated sediments

Sediment bioassays with larvae of the midge, Chironomus tentans, were used to evaluate influences on the bioavailability and toxicity of copper (Cu) in sediments with a wide range of concentrations of metals, acid-volatile sulfide (AVS), and other physicochemical characteristics. Sediments were collected from sixteen lakes in Michigan, USA, and from twelve sites in the Clark Fork River drainage of Montana, USA, which are contaminated with metals from mining activities and from other anthropogenic sources. Bioassays with C. tentans larvae were conducted for ten days in a static-renewal test system, with endpoints of survival, growth, and metal bioaccumulation. Bioaccumulation of copper (Cu) was strongly correlated with Cu concentrations in porewater, and was increased significantly at Cu concentrations less than those affecting growth or survival. Midge survival and growth were not significantly correlated with concentrations of Cu in sediment or porewater, and were poorly predicted by ratios of acid-extractable metals to AVS in sediments. Principal components analysis indicated that Cu concentrations in porewater and bioaccumulation of Cu by midge larvae were influenced by AVS, sediment organic carbon, and porewater pH, and that toxicity was associated with high concentrations of Cu, high concentrations of zinc (Zn) and ammonia. No toxicity was observed in several sediments which contained low concentrations of AVS and high concentrations of Cu and Zn. In sediments which contain little AVS, bioavailability of metals may be controlled by constituents other than sulfides, such as organic matter and metal hydrous oxides. These results indicate that assessments of toxicity in metal-contaminated sediments should evaluate the importance of metal-binding phases other than sulfides, and the possible contributions of ammonia or other toxicants to toxicity in sediment bioassays.The U.S. Government right to retain a non-exclusive, royalty-free licence in and to any copyright is acknowledged.     

Ocean acidification increases the toxicity of contaminated sediments

Ocean acidification (OA) may alter the behaviour of sediment‐bound metals, modifying their bioavailability and thus toxicity. We provide the first experimental test of this hypothesis with the amphipod Corophium volutator. Amphipods were exposed to two test sediments, one with relatively high metals concentrations (Σ_metals 239 mg kg^?1) and a reference sediment with lower contamination (Σ_metals 82 mg kg^?1) under conditions that mimic current and projected conditions of OA (390–1140 μatm pCO₂). Survival and DNA damage was measured in the amphipods, whereas the flux of labile metals was measured in the sediment and water column (WC) using Diffusive Gradients in Thin‐films. The contaminated sediments became more acutely toxic to C. volutator under elevated pCO₂ (1140 μatm). There was also a 2.7‐fold increase in DNA damage in amphipods exposed to the contaminated sediment at 750 μatm pCO₂, as well as increased DNA damage in organisms exposed to the reference sediment, but only at 1140 μatm pCO₂. The projected pCO₂ concentrations increased the flux of nickel and zinc to labile states in the WC and pore water. However, the increase in metal flux at elevated pCO₂ was equal between the reference and contaminated sediments or, occasionally, greater from reference sediments. Hence, the toxicological interaction between OA and contaminants could not be explained by e ffects of pH on metal speciation. We propose that the additive physiological effects of OA and contaminants will be more important than changes in metal speciation in determining the responses of benthos to contaminated sediments under OA. Our data demonstrate clear potential for near‐future OA to increase the susceptibility of benthic ecosystems to contaminants. Environmental policy should consider contaminants within the context of changing environmental conditions. Specifically, sediment metals guidelines may need to be reevaluated to afford appropriate environmental protection under future conditions of OA.     

Global versus Local Conservation Focus of U.S. State Agency Endangered Bird Species Lists

The development of species priorities for conservation at local or regional scales (for example, within a state or province) poses an interesting paradox. One the one hand, locally or regionally-derived species priorities may lead to greater interest in and resources directed to biodiversity conservation by local or regional institutions. On the other hand, locally or regionally-derived species priorities could overlook national or global priorities. We assessed U.S. state government agency endangered-threatened bird lists to determine the comparative representation of species of global versus local conservation significance on them. State lists tended to be represented primarily by species of low global risk-low global responsibility (range: 15–100%; mean 51%) and high global risk-high global responsibility (range: 0–73%; mean 35%). In 25 states, more than half of the species on the state lists were in the low global risk-low global responsibility category. Most U.S. state agency lists represent a combined strategy of highlighting species of both local and global conservation significance. Even with this combined local-global strategy, most state lists were predominated by species that represent local but not global conservation significance. Such a strategy could have profound negative consequences for many species that are not formally recognized under national endangered species protections but that are also left off of state-level endangered species lists.     

Health-Based Criteria for Sediment Disposal Options: A Case Study of the Port of New York/New Jersey

Approximately 4 million cubic yards of sediment are dredged annually from the Port of New York and New Jersey in order to maintain navigable channels. In many cases, the sediments contain elevated levels of numerous contaminants. The New York District of the U.S. Army Corps of Engineers and U.S. Environmental Protection Agency Region II employ a framework of sediment quality evaluation to determine whether contaminated sediments are suitable for open ocean disposal (i.e., do not pose a health risk from bioaccumulation in human food chain) or whether more extensive and costly disposal methods are required. The degree to which chemicals can bioaccumulate from sediments into benthic invertebrates is a key determinant in the permitting decision. The maximally “acceptable” levels of bioaccumulation (bioaccumulation criteria) have been developed over a period of several years, using a variety of different methods. We reviewed the technical bases of these criteria and found that, while some values can be considered “risk-based,” others are based on historical background concentrations, Food and Drug Administration Action Levels, limits of detection, and other non-“risk-based” methodologies. Hence, the degree of uncertainty and health protection (or lack thereof) in the criteria varies considerably among the chemicals. We also reviewed the outcomes of several permit applications and found that the bioaccumulation criteria were not applied consistently. We propose the following refinements to the decision-making process: (1) bioaccumulation screening values based only upon risk-based criteria, using a single method that is applied for all chemicals; (2) increased consistency in decision-making and considerations of site-specific information where appropriate; and (3) assured availability of testing results for review and analysis by interested parties.     

Heavy metal contamination of sediments in the Upper Connecting Channels of the Great Lakes

In 1985, sampling at 250 stations throughout the St. Marys, St. Clair, and Detroit rivers and Lake St. Clair — the connecting channels of the upper Great Lakes — revealed widespread metal contamination of the sediments. Concentrations of cadmium, chromium, copper, lead, mercury, nickel, and zinc each exceeded U.S. Environmental Protection Agency sediment pollution guidelines at one or more stations throughout the study area. Sediments were polluted more frequently by copper, nickel, zinc, and lead than by cadmium, chromium, or mercury. Sediments with the highest concentrations of metals were found (in descending order) in the Detroit River, the St. Marys River, the St. Clair River, and Lake St. Clair. Although metal contamination of sediments was most common and sediment concentrations of metals were generally highest near industrial areas, substantial contamination of sediments by metals was present in sediment deposition areas up to 60 km from any known source of pollution.Contribution 735 of the National Fisheries Research Center-Great Lakes, U.S. Fish and Wildlife Service, 1451 Green Road, Ann Arbor, MI 48105.     

A Comparative Screening-Level Ecological and Human Health Risk Assessment for Dredged Material Management Alternatives in New York/New Jersey Harbor

Managers of New York and New Jersey Harbor dredging projects are developing strategies to dispose and manage the large volumes of sediment that must be dredged to maintain passable waterways. The various management alternatives include aquatic containment facilities, upland containment, and treatment with beneficial reuse. An important consideration in the selection of an appropriate alternative is the evaluation of potential risks to ecological and human receptors. This study presents a framework for a screening-level ecological and human health risk assessment that compares risks associated with management alternatives for contaminated dredged materials. The major objectives of the work were to identify exposure routes that show the potential for risk and develop a framework that can be used to compare relative potential risks among eight management alternatives. Managers can use this framework to: ? identify characteristics of the placement/treatment alternatives that contribute to potential risk, ? choose one alternative over another for sediments with high concentrations of contaminants, ? implement controls that mitigate risk, or ? identify the need for a more comprehensive site-specific risk assessment.     

Development of a sediment bioassay to determine bioavailability of PAHs to fish

Recent work has shown that MFO induction and loss of control of steroid hormone production occurs in fish after exposure to pulp mill effluents, PCBs, PAHs, and some pesticides. We had recently developed laboratory assays to evaluate the effluents on these responses, but were lacking a protocol for a sediment assay. This paper describes the development of a sediment test capable of demonstrating MFO induction in fish. MFO responses were evident in rainbow trout within 4 days of exposure to contaminated sediments. Further testing showed that fish were responding to chemicals from the sediments, but not from bottom water, and a survey of sediment from thirteen contaminated areas showed that MFO induction more closely paralleled PAH levels in the sediments than the observed PCB concentrations. The sites showing MFO induction were also the sites where sediment toxicity was demonstrated with laboratory bioassays using Daphnia magna and Hyalella azteca. The protocol has been further refined to describe the quantity of sediment required and duration of testing. This test will enable us to study the biochemical effects of exposure to contaminated sediments. The protocol could also be used to prioritize areas of contamination and to evaluate dredging impacts and remediation success.     

Assessment of possible sediment toxicity of contaminated sediments in Port Jackson, Sydney, Australia

A considerable amount of chemical data is available for surficial sediments in Port Jackson. Some of the highest concentrations of heavy metals, organochlorines and polycyclic aromatic hydrocarbons of any capital port occur in sediments mantling shallow tributaries and embayments close to central Sydney. However, these data have limited ability to predict adverse effects on living resources and in the absence of toxicological data, sediment quality guidelines (SQG) have been used to assess the possible adverse biological effects of sedimentary contaminants in this estuary. Several SQGs are currently available for both fresh and marine environments, but the scheme used in the current study is based on empirical analysis of matching chemical and biological data compiled by the National Oceanographic and Atmospheric Administration (NOAA) in the U.S. The NOAA SQG can be used to assess individual chemicals, or to estimate the probability of acute sediment toxicity by calculating `mean quotients' for a large range of contaminants. Although many individual chemicals in sediment exceed SQG over extensive parts of Port Jackson, `mean quotient' results suggest that only a small proportion (1%) of the harbour may be highly toxic (74% probability of toxicity). However, sediment in a considerably larger proportion of the port (almost 25%) is estimated to have a 49% probability of being toxic using the `mean quotient' approach. These results are indicative at best and contemporaneous chemical/biological/ecotoxicological studies are needed to verify the applicability of SQG developed in the U.S. for use outside North America and site specific studies of this type are still required to determine the toxicity of sediments in Port Jackson.     

面向管理目标的国家公园生态监测指标体系构建与应用

国家公园具有生态系统保护、自然资源可持续利用等管理目标,这些管理目标的实现需要大量监测数据和信息的支持。对国家公园开展生态监测有助于了解国家公园内生态系统的动态变化并揭示管理活动的影响,从而为管理决策的规划和实施提供有用信息。为推动我国国家公园生态监测体系的建立,提出了面向管理目标的国家公园生态监测指标构建方法。该方法由确定国家公园生态监测目标、识别国家公园管理目标、识别国家公园关键生态过程、确定需要监测的生态过程并制定初始监测指标清单、确定最终监测指标清单5个部分组成。该方法在三江源国家公园进行了应用。三江源国家公园的管理目标包括生态系统保育、维持江河径流量持续稳定等13项,在区域、景观、生态系统和种群尺度上共识别出16个关键生态过程。通过匹配三江源国家公园的关键生态过程与管理目标,构建了一个由两级共93个指标组成的三江源国家公园生态监测指标体系,为三江源国家公园生态监测体系的构建奠定了基础。     

Critical issues in sediment bioassays and toxicity testing

During the past few years there has been a tremendous increase in sediment bioassay and toxicity testing and research. The increased activity has paralleled the development of regulatory interest and realization of the role of contaminated sediments in ecosystem degradation. Many critical issues which affect test responses, data interpretation, and extrapolation to in situ conditions, have not been adequately addressed or recognized by the scientific community. Some of these issues may significantly affect contaminant fate and effects and thereby affect the accuracy of data interpretations. Examples of these interferences are disruptive sample collection, extended sample storage, designs which alter exposure routes, improper spiking conditions and sediment dilution, and inadequate validation of laboratory responses against in situ conditions. Over-simplification of complex sediment interactions may lead to erroneous conclusions concerning the significance of moderate to low levels of contamination.     

The United States and the new law of the sea

Abstract

The official U.S. statement on the 32nd meeting of the International Whaling Commission (IWC termed the outcome a “modest success.”; However, from the point of view of conservationists—i.e., governments and private groups seeking greater protection for the world's endangered whales—the results of the 1980 IWC session can be described at best as satisfactory. The disappointing U.S. performance at this and other recent Commission proceedings strongly suggests the need for a reassessment of American cetacean policy and the way in which we pursue this policy in the IWC.

The discussion will begin with a review of U.S. objectives in the IWC in relation to national and international law governing cetaceans. The focus will then turn to the role played by the United States in the Commission's deliberations on selected issues in 1980. The conclusion will set forth recommendations for improvements in American policy and strategy in the IWC.     

Elevated nitrate enriches microbial functional genes for potential bioremediation of complexly contaminated sediments

Nitrate is an important nutrient and electron acceptor for microorganisms, having a key role in nitrogen (N) cycling and electron transfer in anoxic sediments. High-nitrate inputs into sediments could have a significant effect on N cycling and its associated microbial processes. However, few studies have been focused on the effect of nitrate addition on the functional diversity, composition, structure and dynamics of sediment microbial communities in contaminated aquatic ecosystems with persistent organic pollutants (POPs). Here we analyzed sediment microbial communities from a field-scale in situ bioremediation site, a creek in Pearl River Delta containing a variety of contaminants including polybrominated diphenyl ethers (PBDEs) and polycyclic aromatic hydrocarbons (PAHs), before and after nitrate injection using a comprehensive functional gene array (GeoChip 4.0). Our results showed that the sediment microbial community functional composition and structure were markedly altered, and that functional genes involved in N-, carbon (C)-, sulfur (S)-and phosphorus (P)- cycling processes were highly enriched after nitrate injection, especially those microorganisms with diverse metabolic capabilities, leading to potential in situ bioremediation of the contaminated sediment, such as PBDE and PAH reduction/degradation. This study provides new insights into our understanding of sediment microbial community responses to nitrate addition, suggesting that indigenous microorganisms could be successfully stimulated for in situ bioremediation of POPs in contaminated sediments with nitrate addition.     

湖泊底质与水生植物相互作用综述

简要阐述了湖泊生态系统中底质和水生植物的概念及重要性,综述了底质理化性质对水生植物生长的影响,以及水生植物对底质营养盐的释放和底质再悬浮的作用。通过大量的研究综述回顾论述了不同的湖泊底质类型在一定程度上决定了水生植物的生长状态,适合的底质营养盐范围能促进水生植物生长,不同水生植物对底质营养盐的耐受性有差异。水生植物能促进底质沉降并减少再悬浮,水生植物的存在对沉积物中磷的活性有显著的影响。污染底泥的修复能为水生植物的立地与生长提供了良好的底质条件,有利于富营养化湖泊水生植被的恢复与重建。     

Production of Hexagenia limbata nymphs in contaminated sediments in the Upper Great Lakes Connecting Channels

In April through October 1986, we sampled sediments and populations of nymphs of the burrowing mayfly, Hexagenia limbata (Serville), at 11 locations throughout the connecting channels of the upper Great Lakes, to determine if sediment contaminants adversely affected nymph production. Production over this period was high (980 to 9231 mg dry wt m^-2) at the five locations where measured sediment levels of oil, cyanide, and six metals were below the threshold criteria of the U.S. Environmental Protection Agency and the Ontario Ministry of Environment for contaminated or polluted sediments, and also where the criterion for visible oil given in the Water Quality Agreement between the U.S.A. and Canada for connecting waters of the Great Lakes was not exceeded. At the other six locations where sediments were polluted, production was markedly lower (359 to 872 mg dry wt m^-2). This finding is significant because it indicates that existing sediment quality criteria can be applied to protect H. limbata from oil, cyanide, and metals in the Great Lakes and connecting channels where the species fulfills a major role in secondary production and trophic transfer of energy.Contribution 733, of the National Fisheries Research Center-Great Lakes, U.S. Fish and Wildlife Service, 1451 Green Road, Ann Arbor, MI 48105.     

Entrapment of pollutants in Mediterranean sediments and biogeochemical indicators of their impact

The transit and fate of certain pollutants (Cd, Pb, Zn and P) transported to the western Mediterranean sea-floor and a method to assess their impact are described. The spatial distribution of pollutant concentrations in the Rhône prodelta shows that their decline with distance from their source is due both to mixing with unpolluted sediments, release from contaminated particles during transit and release from sediments after deposition. Beyond the continental shelf, metals of anthropogenic origin, mainly incorporated in faecal pellets, sink and become entrapped in deep sea sediments. Because subsaturating concentrations of trace metals are often found in surface pore waters and storage, therefore, still occurs, co-precipitation with other metal ions existing in slightly supersaturated states has also to be considered. Although phosphate tends to precipitate as apatite after entering sea water, its `definitive' storage in sediments is hindered by certain forms of pollution. Low pH and reducing conditions in sediments enhance phosphate release to the overlying water . Eutrophication may then occur in localised areas. The effects of urban waste water contamination on biogeochemical processes in sediments are examined, in particular processes responsible for the transformation of organic nitrogen. Sediment quality appears to be better defined by the effectiveness of diagenetic processes than by pollutant concentration per se. In general, polluted sediments possess weak capacities to transform organic nitrogen relative to the quantities of organic matter that are available. Such sediment characteristics are indicated by the preferential growth of Caulerpa taxifolia over that of Posidonia oceanica.