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Contaminated Sediment Risk Assessment

Contaminated sediments in rivers and streams, lakes, coastal harbors, and estuaries have the potential to pose ecological and human health risks. The goals of risk assessment applied to contaminated sediments are to characterize the nature and magnitude of the current and potential threats to human health, wildlife and ecosystem functioning posed by contamination; identify the key factors contributing to the potential health and ecological risks; evaluate how implementation of one or more remedy actions will mitigate the risks in the short and long term; and evaluate the risks and impacts from sediment management, both during and after any dredging or other remedy construction activities.

Related Article(s):

Contributor(s):

  • Richard J. Wenning
  • Sabine E. Apitz

Key Resource(s):

  • Contaminated Sediment Remediation Guidance for Hazardous Waste Sites[1]
  • Principles for Environmental Risk Assessment of the Sediment Compartment[2]
  • Assessing and managing contaminated sediments:
Part I, Developing an Effective Investigation and Risk Evaluation Strategy[3]
Part II, Evaluating Risk and Monitoring Sediment Remedy Effectiveness[4]

Introduction

Improving the management of contaminated sediments is of growing concern globally. Sediment processes in both marine and freshwater environments are important to the function of aquatic ecosystems[5], and many organisms rely on certain sediment quality and quantity characteristics for their life cycle[6]. Human health can also be affected by sediment conditions, either via direct contact, as a result of sediment impacts on water quality, or because of the strong influence sediments can have on the quality of fish and shellfish consumed by people[7]. A common approach to achieving the explicit management goals inherent in different sediment assessment frameworks in North America and elsewhere is the use of the ecological risk assessment (ERA)[8]. An ERA “evaluates the likelihood and magnitude of adverse effects from exposure to a chemical for organisms, such as animals, plants, or microbes, in the environment”[9]. An ERA provides information relevant to the management decision-making process[10]. It should be performed in a scientifically based, defensible manner that is cost-effective and protective of human health and the environment[11]. Therefore, science-based methods for assessing sediment quality and use of risk-based decision-making in sediment management are important for identifying conditions suspected to adversely affect ecological and human services provided by sediments, and predicting the likely consequences of different sediment management actions[12][13].

Sediment risk assessment is increasingly used by governmental agencies to support sediment management in freshwater, estuarine, and marine environments. Strategies for sediment management encompass a wide variety of actions, from removal, capping or treatment of contaminated sediment to the monitoring of natural processes, including sedimentation, binding, and bio- and photo-degradation that serve to reduce the potential threat to aquatic life over time. It is not uncommon to revisit a sediment risk assessment periodically to check how changed environmental conditions reflected in sediment and biotic sampling work has either reduced or exacerbated the threats identified in the initial assessment.

At present, several countries lack common recommendations specific to conducting risk assessment of contaminated sediments[14]. In the European Union, sediment has played a secondary role in the Water Framework Directive (WFD), with most quality standards being focused on water with the option for the development of national standards for sediment and biota for bioaccumulative compounds. The Common Implementation Strategy (CIS) in 2010 provided guidance on the monitoring of contaminants in sediments and biota, but not on risk-based decision-making[15]. There are efforts underway to incorporate guidance for management of contaminated sediment in the Common Implementation Strategy in 2021[16]. Sediment risk assessment guidance from Norway, Canada, the Netherlands, and the US are most often referenced when assessing the risks from contaminated sediments[14][17][18]. Some European countries, such as Norway, have focused their risk assessment guidance on the assessment of sediment conditions relative to general chemical thresholds, while in North America, risk assessment guidance focuses on site- or region-specific conditions[19].

There is general consensus from a regulatory perspective, globally, on the importance of sediment risk assessment. Technical guidance documents prepared by Canada[20][21] , the European Union[2], and the United States Environmental Protection Agency (USEPA)[1] advise a flexible, tiered approach for sediment risk assessment. Sediment quality guidelines in many countries reflect the scientific importance of including certain sediment-specific measurement and biotic assessment endpoints, as well as certain physical sediment processes and chemical transformation processes potentially affecting biotic responses to contaminant exposure in the sediment[22]. New risk assessment methods continue to emerge in the scientific literature[23][24][25]. These new methods, however, are likely to be considered supplemental to the more generalized framework shared globally.

Fundamentals of Sediment Risk Assessment

Figure 1. Schematic of the sediment risk assessment process

Whereas there is strong evidence of anthropogenic impacts on the benthic community at many sediment sites, the degree of toxicity (or even its presence or absence) cannot be predicted with absolute certainty using contaminant concentrations alone[13]. A sediment ERA should include lines of evidence (LOEs) derived from several different investigations[22]. One common approach to develop several of these LOEs in a decision framework is the triad approach. Triad-based assessment frameworks require evidence based on sediment chemistry, toxicity, and benthic community structure (possibly including evidence of bioaccumulation) to designate sediment as toxic and requiring management or control[26]. In some decision frameworks, particularly those used to establish and rank risks in national or regional programs, all components of the triad are carried out simultaneously, with the various LOEs combined to support weight of evidence (WOE) decision making. In other frameworks, LOEs are tiered to minimize costs by collecting only the data required to make a decision and leaving some potential consequences and uncertainties unresolved.

Figure 1 provides an overview of a sediment risk assessment process. The first step, and a fundamental requirement, in sediment risk assessment, involves scoping and planning prior to undertaking work. This is important for optimizing the available assessment resource and conducting an assessment at the appropriate level of detail that is transparent and free, to the extent possible, of any bias or preconceived beliefs concerning the outcome[27].

Screening-Level Risk Assessment (SLRA)

Technical guidance in many countries strongly encourages sediment risk assessment to begin with a Screening-Level Risk Assessment (SLRA)[1][2][20]. The SLRA is a simplified risk assessment conducted using limited data and often assuming certain, generally conservative and generic, sediment characteristics, sediment contaminant levels, and exposure parameters in the absence of sufficient readily available information[28][29][30][31].

The analysis is often semi-quantitative, and typically includes comparisons of various chemical and physical sediment conditions to threshold limits established in national or international regulations or by generally accepted scientific interpretations. US technical guidance encourages the comparison of contaminant measurements in water, sediment, or soil to National Oceanographic and Atmospheric Administration (NOAA) sediment screening quick reference tables, or SQuiRT cards, which list quality guidelines from a range of sources, based on differing narrative intent[32].

The screening level approach is intended to minimize the chances of concluding that there is no risk when, in fact, risk may exist. Thus, the results of an SLRA may indicate contaminants or sediments in certain locations in the original study area initially thought to be of concern are acceptable (i.e., contaminant levels are below threshold levels), or that contaminant levels are high enough to indicate immediate action without further assessment (e.g., contaminant levels are well above probable-effects guidelines). In other cases, or at other locations, SLRA may indicate the need for further examination. Further study may apply site-specific, rather than generic and conservative assumptions, to reduce uncertainty.

Detailed Risk Assessment

Detailed sediment risk assessment is conducted when SLRA results indicate one or more sediment contaminants exceed background conditions or regulatory threshold limits. For some contaminants, such as the dioxins and other persistent, bioaccumulative, and toxic substances (PBTs), technical guidance may mandate further examination, regardless of whether threshold levels are exceeded[33][34]. Detailed sediment risk assessment typically follows a three-step framework similar to that described for ecological risk assessment - problem formulation, exposure analysis, and risk characterization[35].

US sediment management guidance describes a detailed risk assessment process similar to that followed for US ecological risk assessment[1]. The first step is problem formulation. It involves defining chemical and physical conditions, delineating the spatial footprint of the sediment area to be examined, and identifying the human uses and ecological features of the sediment. Historical data are included in this initial step to better understand the results of biota, sediment, and water sampling as well as laboratory toxicity testing results. The SLRA is often included as a part of problem formulation.

The second step is exposure analysis. This step includes the identification of pathways by which human and aquatic organisms might directly or indirectly contact contaminants in the sediment. The exposure route (i.e., ingestion, dermal, or inhalation of particulates or gaseous emissions) and both the frequency and duration of contact (i.e., hourly, daily, or seasonally) are determined for each contaminant exposure pathway and human and ecological receptor. The environmental fate of the contaminant, factors affecting uptake, and the overall exposure dose are included in the calculation of the level of contaminant exposure. The exposure analysis also includes an effects assessment, whereby the biological response and associated level required to manifest different biological responses are determined for each contaminant.

The third step is risk-characterization. It involves calculating the risks for each human and ecological receptor posed by each sediment contaminant, as well as the cumulative risk associated with the combined exposure to all contaminants exerting similar biological effects. An uncertainty analysis is often included in this step of the risk assessment to convey where knowledge or data are lacking regarding the presence of the contaminant in the sediment, the biological response associated with exposure to the contaminant, or the behavior of the receptor with respect to contact with the sediment. A sensitivity analysis also may be conducted to convey the range of exposures (lowest, typical, and worst-case) and risks associated with changes in key assumptions and parameter values used in the exposure calculations and effects assessment.

Key Considerations

Cap Design and Materials for Habitat Restoration

In addition to providing chemical isolation and containment, a cap can also be used to provide improvements for organisms by enhancing the habitat characteristics of the bottom substrate[36][37][38]. Often, contaminated sediment environments are degraded for a variety of reasons in addition to the toxic constituents. One way to overcome this is to provide both a habitat layer and chemical isolation or contaminant capping layer. Figure 2 illustrates just such a design providing a more appropriate habitat enhancing substrate, in this case by incorporation additional organic material, vegetation and debris, which is often used by fish species for protection, into the surface layer. In a high energy environment, it should be recognized that it may not be possible to keep a suitable habitat layer in place during high flow events. This would be true of suitable habitat that had developed naturally as well as a constructed habitat layer and it is presumed that if such a habitat is the normal condition of the waterbody that it will recover over time between such high flow events.

Summary

Clean substrate can be placed at the sediment-water interface for the purposes of reducing exposure to and risk from contaminants in the sediments. The cap can consist of simple materials such as sand designed to physically stabilize contaminated sediments and separate the benthic community from those contaminants or may include other materials designed to sequester contaminants even under adverse conditions including strong groundwater upwelling or highly mobile contaminants. The surface of a cap may be designed of coarse material such as gravel or cobble to be stable under high flow events or designed to be more appropriate habitat for benthic and aquatic organisms. As a result of its flexibility, simplicity and low cost relative to its effectiveness, capping is one of the most prevalent remedial technologies for sediments.

References

  1. ^ 1.0 1.1 1.2 1.3 United States Environmental Protection Agency (USEPA), 2005. Contaminated Sediment Remediation Guidance for Hazardous Waste Sites. Office of Solid Waste and Emergency Response, Washington, D.C. EPA-540-R-05-012. OSWER 9355.0-85. Free download from: USEPA   Report.pdf
  2. ^ 2.0 2.1 2.2 Tarazona, J.V., Versonnen, B., Janssen, C., De Laender, F., Vangheluwe, M. and Knight, D., 2014. Principles for Environmental Risk Assessment of the Sediment Compartment: Proceedings of the Topical Scientific Workshop. 7-8 May 2013. European Chemicals Agency, Helsinki. Document ECHA-14-R-13-EN. Free download from: European Chemicals Agency   Report.pdf
  3. ^ Apitz, S.E., Davis, J.W., Finkelstein, K., Hohreiter, D.W., Hoke, R., Jensen, R.H., Jersak, J., Kirtay, V.J., Mack, E.E., Magar, V.S. and Moore, D., 2005. Assessing and Managing Contaminated Sediments: Part I, Developing an Effective Investigation and Risk Evaluation Strategy. Integrated Environmental Assessment and Management, 1(1), pp. 2-8. DOI: 10.1897/IEAM_2004a-002.1 Free access article from: Society of Environmental Toxicology and Chemistry   Report.pdf
  4. ^ Apitz, S.E., Davis, J.W., Finkelstein, K., Hohreiter, D.W., Hoke, R., Jensen, R.H., Jersak, J., Kirtay, V.J., Mack, E.E., Magar, V.S. and Moore, D., 2005b. Assessing and Managing Contaminated Sediments: Part II, Evaluating Risk and Monitoring Sediment Remedy Effectiveness. Integrated Environmental Assessment and Management, 1(1), pp.e1-e14. DOI: 10.1897/IEAM_2004a-002e.1
  5. ^ Apitz, S.E., 2012. Conceptualizing the role of sediment in sustaining ecosystem services: Sediment-Ecosystem Regional Assessment (SEcoRA), Science of the Total Environment, 415, pp. 9-30. DOI:10.1016/j.scitotenv.2011.05.060 Free download from: Academia.edu
  6. ^ Hauer, C., Leitner, P., Unfer, G., Pulg, U., Habersack, H. and Graf, W., 2018. The Role of Sediment and Sediment Dynamics in the Aquatic Environment. In: Schmutz S., Sendzimir J. (ed.s) Riverine Ecosystem Management. Aquatic Ecology Series, vol. 8, pp. 151-169. Springer. DOI: 10.1007/978-3-319-73250-3_8 Open access book from: SpringerOpen
  7. ^ Greenfield, B.K., Melwani, A.R. and Bay, S.M., 2015. A Tiered Assessment Framework to Evaluate Human Health Risk of Contaminated Sediment. Integrated Environmental Assessment and Management, 11(3), pp. 459-473. DOI: 10.1002/ieam.1610
  8. ^ US Environmental Protection Agency (USEPA), 1997. The Incidence and Severity of Sediment Contamination in Surface Waters of the United States: Volume 1, National Sediment Quality Survey. EPA-823R-97-006. Washington, DC. Report.pdf
  9. ^ Society of Environmental Toxicology and Chemistry (SETAC), 2018. Technical Issue Paper: Environmental Risk Assessment of Chemicals. SETAC, Pensacola, FL. 5 pp. Free download from: SETAC   Report.pdf
  10. ^ Stahl, R.G., Bachman, R., Barton, A., Clark, J., deFur, P., Ells, S., Pittinger, C., Slimak, M., Wentsel, R., 2001. Risk Management: Ecological Risk-Based Decision Making. SETAC Press, Pensacola, FL, 222 pp. ISBN: 978-1-880611-26-5
  11. ^ Chief of Naval Operations (CNO), 1999. Navy Policy for Conducting Ecological Risk Assessments, Letter 5090, Ser N453E/9U595355, dated 05 April 99. Department of the Navy, Washington, DC. Free download from: the US Navy   Report.pdf
  12. ^ Bridges, T.S., Apitz, S.E., Evison, L., Keckler, K., Logan, M., Nadeau, S. and Wenning, R.J., 2006. Risk‐Based Decision Making to Manage Contaminated Sediments. Integrated Environmental Assessment and Management, 2(1), pp. 51-58. DOI: 10.1002/ieam.5630020110 Free access article from: SETAC
  13. ^ 13.0 13.1 Apitz, S.E., 2011. Integrated Risk Assessments for the Management of Contaminated Sediments in Estuaries and Coastal Systems. In: Wolanski, E. and McLusky, D.S. (eds.) Treatise on Estuarine and Coastal Science, Vol 4, pp. 311–338. Waltham: Academic Press. ISBN: 9780123747112
  14. ^ 14.0 14.1 Bruce, P., Sobek, A., Ohlsson, Y. and Bradshaw, C., 2020. Risk assessments of contaminated sediments from the perspective of weight of evidence strategies – a Swedish case study. Human and Ecological Risk Assessment, 27(5), pp. 1366-1387. DOI: 10.1080/10807039.2020.1848414   Website
  15. ^ European Commission, 2010. Common Implementation Strategy For The Water Framework Directive (2000/60/EC), Technical Report - 2010 – 041; Guidance document No. 25 On Chemical Monitoring Of Sediment And Biota Under The Water Framework Directive. 82pp. ISBN 978-92-79-16224-4. Free download
  16. ^ Brils, J., 2020. Including sediment in European River Basin Management Plans: Twenty years of work by SedNet. Journal of Soils and Sediments, 20(12), pp.4229-4237. DOI: 10.1007/s11368-020-02782-1   Open Access Article
  17. ^ Birch, G.F., 2018. A review of chemical-based sediment quality assessment methodologies for the marine environment. Marine Pollution Bulletin, 133, pp.218-232. DOI: 10.1016/j.marpolbul.2018.05.039
  18. ^ Kwok, K.W., Batley, G.E., Wenning, R.J., Zhu, L., Vangheluwe, M. and Lee, S., 2014. Sediment quality guidelines: challenges and opportunities for improving sediment management. Environmental Science and Pollution Research, 21(1), pp. 17-27. DOI: 10.1007/s11356-013-1778-7 Free download from: ResearchGate
  19. ^ Apitz, S.E., 2008. Is risk-based, sustainable sediment management consistent with European policy?. Journal of Soils and Sediments, 8(6), p.461-466. DOI: 10.1007/s11368-008-0039-8   Free download from: Academia.edu
  20. ^ 20.0 20.1 Fletcher, R., Welsh, P. and Fletcher, T., 2008. Guidelines for Identifying, Assessing, and Managing Contaminated Sediments in Ontario. Ontario Ministry of the Environment. PIBS6658e. Website
  21. ^ Health Canada, 2017. Supplemental Guidance on Human Health Risk Assessment of Contaminated Sediments: Direct Contact Pathway, Federal Contaminated Site Risk Assessment in Canada. ISBN: 978-0-660-07989-9. Cat.: H144-41/2017E-PDF. Pub. 160382. Free download from: Health Canada   Report.pdf
  22. ^ 22.0 22.1 Wenning, R.J. Batley, G.E., Ingersoll, C.G., and Moore, D.W., (eds), 2005. Use Of Sediment Quality Guidelines And Related Tools For The Assessment Of Contaminated Sediments. SETAC, Pensacola, FL. 815 pp. ISBN 1-880611-71-6.
  23. ^ Benson, N.U., Adedapo, A.E., Fred-Ahmadu, O.H., Williams, A.B., Udosen, E.D., Ayejuyo, O.O. and Olajire, A.A., 2018. A new method for assessment of sediment-associated contamination risks using multivariate statistical approach. MethodsX, 5, pp. 268-276. DOI: 10.1016/j.mex.2018.03.005   Free Access Article   Report.pdf
  24. ^ Saeedi, M. and Jamshidi-Zanjani, A., 2015. Development of a new aggregative index to assess potential effect of metals pollution in aquatic sediments. Ecological Indicators, 58, pp. 235-243. DOI: 10.1016/j.ecolind.2015.05.047 Free download from: Academis.edu
  25. ^ Väänänen, K., Leppänen, M.T., Chen, X. and Akkanen, J., 2018. Metal bioavailability in ecological risk assessment of freshwater ecosystems: from science to environmental management. Ecotoxicology and Environmental Safety, 147, pp. 430-446. DOI: 10.1016/j.ecoenv.2017.08.064
  26. ^ Chapman, P.M., Paine, M.D., Arthur, A.D., Taylor, L.A., 1996. A triad study of sediment quality associated with a major, relatively untreated marine sewage discharge. Marine Pollution Bulletin 32(1), pp. 47–64. DOI: 10.1016/0025-326X(95)00108-Y
  27. ^ Hill, R.A., Chapman, P.M., Mann, G.S. and Lawrence, G.S., 2000. Level of Detail in Ecological Risk Assessments. Marine Pollution Bulletin, 40(6), pp. 471-477. DOI: 10.1016/S0025-326X(00)00036-9
  28. ^ Hope, B.K., 2006. An examination of ecological risk assessment and management practices. Environment International, 32(8), pp. 983-995. DOI: 10.1016/j.envint.2006.06.005
  29. ^ Weinstein, J.E., Crawford, K.D., Garner, T.R. and Flemming, A.J., 2010. Screening-level ecological and human health risk assessment of polycyclic aromatic hydrocarbons in stormwater detention pond sediments of Coastal South Carolina, USA. Journal of Hazardous Materials, 178(1-3), pp. 906-916. DOI: 10.1016/j.jhazmat.2010.02.024
  30. ^ Rak, A., Maly, M.E., Tracey, G., 2008. A Guide to Screening Level Ecological Risk Assessment, TG-090801. Tri-Services Ecological Risk Assessment Working Group (TSERAWG), U.S. Army Biological Technical Assistance Group (BTAG), Aberdeen Proving Ground, MD. 26 pp. Free Download   Report.pdf
  31. ^ US Environmental Protection Agency (USEPA), 2001. ECO Update. The Role of Screening-Level Risk Assessments and Refining Contaminants of Concern in Baseline Ecological Risk Assessments. EPA 540/F-01/014. Washington, D.C. Website   Report.pdf
  32. ^ Buchman, M.F., 2008. Screening Quick Reference Tables (SQuiRTs), NOAA OR&R Report 08-1. National Oceanographic and Atmospheric Administration (NOAA), Coastal Protection and Restoration Protection Division. 34 pp. website   Report.pdf
  33. ^ Solomon, K., Matthies, M., and Vighi, M., 2013. Assessment of PBTs in the European Union: a critical assessment of the proposed evaluation scheme with reference to plant protection products. Environmental Sciences Europe, 25(1), pp. 1-17. DOI: 10.1186/2190-4715-25-10   Open Access Article
  34. ^ Matthies, M., Solomon, K., Vighi, M., Gilman, A. and Tarazona, J.V., 2016. The origin and evolution of assessment criteria for persistent, bioaccumulative and toxic (PBT) chemicals and persistent organic pollutants (POPs). Environmental Science: Processes and Impacts, 18(9), pp. 1114-1128. DOI: 10.1039/C6EM00311G
  35. ^ Suter, G.W., 2008. Ecological Risk Assessment in the United States Environmental Protection Agency: A Historical Overview. Integrated Environmental Assessment And Management, 4(3), pp. 285-289. DOI: 10.1897/IEAM_2007-062.1   Free download from: BioOne
  36. ^ Yozzo, D.J., Wilber, P. and Will, R.J., 2004. Beneficial use of dredged material for habitat creation, enhancement, and restoration in New York–New Jersey Harbor. Journal of Environmental Management, 73(1), pp. 39-52. DOI: 10.1016/j.jenvman.2004.05.008
  37. ^ Zhang, C., Zhu, M.Y., Zeng, G.M., Yu, Z.G., Cui, F., Yang, Z.Z. and Shen, L.Q., 2016. Active capping technology: a new environmental remediation of contaminated sediment. Environmental Science and Pollution Research, 23(5), pp.4370-4386. DOI: 10.1007/s11356-016-6076-8
  38. ^ Cite error: Invalid <ref> tag; no text was provided for refs named Vlassopoulos2017

See Also

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