title / The Use Of Action Levels in The Assessment of Dredged Material Placement at Sea and in Estuarine Areas under FEPA (II)
/ DEFRA
project code / AE0258
Department for Environment, Food and Rural Affairs CSG 15
Research and Development
Final Project Report
(Not to be used for LINK projects)
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Project title / The Use Of Action Levels in The Assessment of Dredged Material Placement at Sea and in Estuarine Areas under FEPA (II)
DEFRA project code / AE0258
Contractor organisation and location / Cefas
Burnham -on-Crouch
Total DEFRA project costs / £
Project start date / 01/04/01 / Project end date / 31/03/03
Executive summary (maximum 2 sides A4)
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CSG 15 (Rev. 6/02) 2
Projecttitle / The Use Of Action Levels in The Assessment of Dredged Material Placement at Sea and in Estuarine Areas under FEPA (II)
/ DEFRA
project code / AE0258
1.0 Executive Summary
The focus of this project was to document the way in which Action Levels are used and to review the current Action Levels used internally by CEFAS to aid the assessment of disposal of dredged material at sea. This review takes account of the following important issues: regional differences in geology and sediment quality, application to individual samples or the mean of a group of samples, the sensitivity of disposal sites, beneficial placement in non-dispersive areas and the potential implications for any sampling strategy set. Action levels are used routinely within the FEPA (II) Assessment team, as an integral stage in the assessment of the suitability for the disposal of dredged material to sea. Current Action Levels were implemented during 1995, making it imperative to review these levels in the light of scientific advancements and greater emphasis on conservation issues and biological effects. Action Level derivation was also required for those determinants without current sediment quality criteria, such as Brominated Flame retardants and Booster biocides which have some potential for environmental concern in relation to dredged material disposal. These levels, however, could only be derived where it was deemed that sufficient scientific data existed pertaining to the presence of these chemicals in current sediments, or toxicological data was available.
The central aim of this project was to review and provide a robust set of Action Levels for contaminants in dredged material and make provisions for further revision of these levels, dependent on the findings of this project.
Previous use of such guidelines has concentrated heavily on the concentrations and load of contaminants within the sediments. Action Levels were previously derived from data on concentrations of contaminants in dredged material from England and Wales and used limited toxicological information. As part of this review it was felt that biological responses to contaminants should be integrated into the production of new Action Levels where sufficient scientific data existed to support this approach.
Initially literature reviews were provided for each individual contaminant of interest. These reviews provided background information on the natural occurrence, anthropogenic input, environmental fate, toxicological effects, sediment dynamics, bioavailability and current sediment concentration data for each individual contaminant. Our present data sets contain adequate data values for a large number of common contaminants in dredged material for which Action Levels can be derived, however further work was required to produce suitable data on bioavailability and bioaccumulation in some of the less well researched contaminants investigated.
In order to meet the objectives of the project, the information derived from the literature review was used to drive data interpretation from the DAS (Disposal at Sea) data system. A number of approaches towards setting sediment quality criteria, using some measure of biological effects, have been suggested in the literature. It is not the intention of this paper to review all these approaches, except to observe that perhaps the most developed of these have been produced by Long and McDonald (Long et al, 1995; Long and MacDonald, 1998) in the US. Their data sets, which took a statistical approach in matching biological and chemical data from modelling, laboratory and field studies in North America, have since been developed to set sediment quality guidelines in a number of countries, notably the US, Canada and Hong Kong. Chemical concentrations only were used to derive effects range-low (ERL) and effects range-median (ERM) sediment quality criteria. However, calculation of Threshold Effects Levels (TEL) and Probable Effects Levels (PEL) values incorporated concentrations associated with both effects and no observed effects (Long and MacDonald, 1998).
Some work has been reported assessing the “accuracy” of sediment quality guidelines. ERL and ERM values were used to define concentration ranges that were i) rarely (eg <10%) ii) occasionally (usually ~25%) or iii) frequently (usually ~70%) associated with adverse effects (Long and MacDonald, 1998). To assist in the management of prioritisation of sediments, these authors (ibid) reported results from studies where multiple exceedances of ERMs were observed. Their data showed, for example, that 40-60% of samples in which individual ERMs or PELs were exceeded proved to be highly toxic in amphipod survival tests. With respect to mixtures, where >10 ERMs (or >21 PELs) were exceeded, the probability of observing toxicity in amphipod survival tests was 74-88%. Where concentrations of substances were below the ERL or TEL, the incidence of effects was generally below 16% (Long and MacDonald, 1998). Such data provide confidence in effectiveness of the ERM and PEL approach.
The revised Action Levels derived here are proposed for use by CEFAS as part of a 'weight of evidence' approach to assessing dredged material and its suitability for disposal to sea. This CEFAS assessment will be used, by Defra, in conjunction with a range of other evidence (including social and economic factors) to make management decisions regarding the fate of dredged material. This integrated approach is in line with recent discussions regarding weight of evidence approaches to environmental management of sediments (Burton et al,2002, Chapman et al).
CSG 15 (Rev. 6/02) 2
Projecttitle / The Use Of Action Levels in The Assessment of Dredged Material Placement at Sea and in Estuarine Areas under FEPA (II)
/ DEFRA
project code / AE0258
Scientific report (maximum 20 sides A4)
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CSG 15 (Rev. 6/02) 2
Projecttitle / The Use Of Action Levels in The Assessment of Dredged Material Placement at Sea and in Estuarine Areas under FEPA (II)
/ DEFRA
project code / AE0258
1.1 The current use of Action Levels in the Assessment of the acceptability of dredged material for sea disposal under FEPA (II) 1985 in England and Wales.
Action Levels are used as part of the ‘weight of evidence’ approach used for the assessment of the acceptability of dredged material for sea disposal. Current assesment practices also rely on the interpretation of additional data such as the physical nature of the sdiment, the suitability and capacity of the disposal site, the patterns of sediment movement from the disposal site and the location of areas of conservation status or importance for fisheries resource of fisheries activity.
Currently within the UK two Action Levels are used, Action Level 1 and Action Level 2. Materials with contamination levels below Action Level 1 would be unlikely to be refused sea disposal licence, on the ground of contamination. Values below this ‘benchmark’ level are considered to have very low levels of anthropogenic contamination. Materials with contamination levels above Action Level 2 are likely to be deemed unacceptable for sea disposal.
Those samples which have contamination levels between Action Levels 1 and 2 requires further evaluation. For example this could involve additional sampling and/or further analysis or the use of bioassays to more effectively assess the risk to the environment.
1.2 International Guidance and ICES.
Several other countries have been setting Action Levels in the recent past, and others are in the process of so doing. ICES WGMS (Working Group on Marine Sediments) are currently drawing up an inventory of sediment quality criteria among member states for both environmental quality and dredge material assessment http://www.ices.dk/reports/MHC/2002/WGMS02.pdf. This activity is being co-ordinated by Caroline Whalley (CEFAS), and draft versions of that text are used to guide the current work.
Metals.
The approach taken to deriving metals action levels has been to:
i) To aim Action Level 1 values towards background estuarine concentrations, mainly using sediment chemistry;
ii) To allow Action Level 2 values to be guided by ecotoxicologically-derived data as well as sediment chemistry.
Note that since various initiatives are under way to derive further background values for sediments from the UK (e.g. A0257 lead by Dr Vivian, and work for NMMPAQC), it may be appropriate to review the Action Level 1 values for metals in 2004-5.
Data being used to assess the existing CEFAS Action Level guidelines fall into five groups:
· Frequency distributions of metal concentrations in individual samples from DAS applications over the years 1998-2001.
· A nominal “background” value, using the 50th percentile of a dataset made up of sediment metal concentrations from 22 estuaries from around England and Wales (Rowlatt et al, 1995) (these values should be reviewed in 2004-05).
· Ecotoxicologically-derived standards for metals in sediments, which are mostly based on data collected and compiled in North America.
· Action level data collected by OSPAR (1998) and ICES WGMS (in prep) for European countries – most of these values are derived from sediment chemistry.
· Historic DAS datasets for England and Wales considering mean metal concentrations in dredged material sent for disposal over the years 1985-2001.
Table 1 illustrates the Action Levels for metals exisitng in various states and the proposed values for England and Wales.
Table 1: Action Levels for metals existing in various states and proposed values for England and Wales.
mg kg-1 dwEcotoxicological standards / Chemistry (mainly)
Metal / NOAA guidelines / Canada / Hong Kong / ICES WGMS range of values / Estuaries ~50%ile (insert other relevant data as they become available) / England and Wales existing guidelines (approx value dry wt) / England and Wales proposed guidelines / proposed change in AL1n compared to AL1
ERL / TEL / ISQV-low / AL1 / AL1n
As / 8.2 / 7.24 / 8.2 / 20 - 80 / 17 / 20 / 20 / =
Cd / 1.2 / 0.676 / 1.5 / 0.5 - 2.5 / 0.4 / 0.4 / 0.4 / =
Cr / 81 / 52.3 / 80 / 60 - 300 / 60 / 40 / 50 /
Cu / 34 / 18.7 / 65 / 20 - 150 / 30 / 40 / 30 /
Hg / 0.15 / 0.13 / 0.28 / 0.1 - 1 / 0.25 / 0.3 / 0.25 /
Ni / 20.9 / 15.9 / 40 / 37 - 130 / 30 / 20 / 30 /
Pb / 46.7 / 30.2 / 75 / 30 - 120 / 60 / 50 / 50 / =
Zn / 150 / 124 / 200 / 160 - 700 / 175 / 130 / 130 / =
Metal / NOAA guidelines / Canada / Hong Kong / ICES WGMS range of values / Estuaries ~50%ile (insert other relevant data as they become available) / England and Wales existing guidelines (approx value dry wt) / England and Wales proposed guidelines / proposed change in AL2n compared to AL2
ERM / PEL / ISQV-high / AL2 / AL2n
As / 70 / 41.6 / 70 / 50 - 1000 / 17 / 50-100 / 70
Cd / 9.6 / 4.21 / 9.6 / 2.4 - 12.5 / 0.4 / 5 / 4 /
Cr / 370 / 160 / 370 / 180 - 5000 / 60 / 400 / 370 /
Cu / 270 / 108 / 270 / 90 - 1500 / 30 / 400 / 300 /
Hg / 0.71 / 0.7 / 1 / 0.8 - 5 / 0.25 / 3 / 1.5 /
Ni / 51.6 / 42.8 / * / 45 - 1500 / 30 / 200 / 150 /
Pb / 218 / 112 / 218 / 100 - 1500 / 60 / 500 / 400 /
Zn / 410 / 271 / 410 / 500 - 10000 / 175 / 800 / 600 /
Action levels for metals in dredge material disposal applications in England and Wales have been reviewed. A nominal “background” concentration, based on sediment chemistry, was used in derivation of Action Level 1. Ecotoxicological data, based largely on datasets from the US, was used to guide the setting of Action Level 2.
Changes in existing, internal guidelines for Action Level 1 have been proposed - a reduction in value for copper and mercury, and an increase in the value for chromium and nickel. Reductions in the guideline Action Level 2 have been proposed for all the metals under consideration
Management concerns over the potential for adverse effects caused by sediment associated chemicals, in this case trace metals, will be practically focused on those chemicals whose concentrations have been augmented above those that would be expected to occur naturally. This data has been derived from current DAS data sets, however should be reviewed in light of the findings of parallel report where nominal “background” values are to be established for sediments around the UK. This will also apply to other contaminants in future studies.