S13 Mercury in the marine environment and transboundary indicators

Thursday, 28 July, 2011

RS13-O1 — 8:30-8:45
Authors: HUBER, Michael.E1, KERSHAW, Peter1, KEENAN, Helen.E1, BOWMER, Tim1
(1)GESAMP, mhuber@bigpond.net.au

The Joint Group of Experts on the Scientific Aspects of Marine Environmental Protection (GESAMP) is an advisory body, established in 1969, that advises the United Nations (UN) system on the scientific aspects of marine environmental protection.

At present GESAMP is jointly sponsored by nine UN organizations with responsibilities relating to the marine environment, and they utilize GESAMP as a mechanism for coordination and collaboration among them. GESAMP functions are to conduct and support marine environmental assessments, to undertake in-depth studies, analyses, and reviews of specific topics, and to identify emerging issues regarding the state of the marine environment. Studies and assessments are usually carried out by dedicated working groups, most of whose members are not sitting members of GESAMP but part of the broader GESAMP network. This presentation will describe and review the current role of GESAMP with particular reference to the UNEP/GEF TWAP (Trans boundary Waters Assessment Programme) Among the constraints to effective management of transboundary waters is the lack of a systematic and scientifically-robust methodology for assessing the changing conditions of the five different types of trans boundary water systems resulting from human and natural causes, which would allow the policy makers, Global Environment Facility and international organisations to set science-based priorities for financial resource allocation. Such a methodology also would facilitate identification and assessment of positive changes in the environmental and resources situations in the trans boundary water systems resulting from interventions by national authorities and international/regional communities. Such a global, comprehensive assessment has not yet been undertaken. However GESAMP is actively involved in the development of an improved, ecosystem-based methodology in Large Marine Ecosystems (LMEs) through pollutant indicators such as mercury and its compounds, POPs and other pollutants that cross trans boundary water systems. The efforts of the GESAMP initiative to this programme will be fully discussed.

RS13-O2 — 8:45-9:00
Authors: KEENAN, Helen.1, BANGKEDPHOL, Sornnarin2, ALO, Babajide3, DAVIDSON, Christine.M3, GUIMERAES, Jean3, HORVAT, Milena3, HURLEY, James 3, LEANER, Joy3, MASON, Robert3, SONGSASEN, Apisit3, TAKASHI, Tomiyasu3, VASILEVA-VELEVA, Emelia3, BOOTH, Peter.H4
(1) Chair GESAMP WG 37, University of Strathclyde, h.e.keenan@strath.ac.uk; (2) ; (3) GESAMP WG 37; (4) DLCS, University of Strathclyde, Glasgow, UK.

GESAMP (Joint Group of Experts on the Scientific Aspects of Marine Environmental Protection) continues to play a leading role in the assessment of global marine pollution. The regular sessions of GESAMP over more than 30 years have produced a large number of reports and studies relating to marine pollution problems, covering a wide range of topics of the greatest relevance to marine environmental policy. The work of the GESAMP is accomplished through working groups with participation of a large number of experts selected by the organizations sponsoring GESAMP. The co-ordination of GESAMP is provided by a joint secretariat of the sponsoring organizations. WG 37 was formed at the request of UNEP with a particular remit for mercury in the aquatic environment. The remit was to target an assessment of the main contributions to the global mercury budget with particular reference to the aquatic environment, possible control options, transformations, pathways and toxicity and how these parameters can be measured or evaluated. A compilation of fate and transport models and current measuring techniques was also assessed. Monitoring efforts were evaluated and showed disparity between the northern and southern hemisphere and it was concluded that developing countries are severley hindered by lack of environmental protection regulations and a need for capacity building. A list of all participants and the main areas covered by the assessment will be presented in full.

RS13-O3 — 9:00-9:15
Authors: KOCMAN, David1, HORVAT, Milena1
(1) Jožef Stefan Institute, Slovenia, david.kocman@ijs.si

In the last decade, considerable progress has been made in better understanding of sources, transport routes and behaviour of mercury in global environment. A lot of effort including modelling was made to assess global mercury releases from variety of sources and policy makers have also taken the advantage of improved information on emissions to assess the effectiveness of measures aimed to reduce the impact of this highly toxic contaminant on human health and ecosystems. However, in these assessments, primarily anthropogenic mercury releases to the atmosphere are covered, while releases to the hydrosphere are usually not taken into account or neglected, especially those associated with contaminated sites. Therefore, here we attempt to estimate for the first time the contribution of mercury releases from mercury contaminated sites to global mercury hydrologic budget. In the assessment, two types of hydrologic releases were considered: (a) riverine flow as a result of erosion of mercury wastes, contaminated soils and sediments, and (b) remobilization and dispersion of mercury from coastal areas previously contaminated by mercury either by river inflows or point sources located in the coastal sites. Globally, we identified over 4000 contaminated sites associated with mercury mining, precious metal processing, non-ferrous metal production and various polluted industrial (e.g. chlor-alkali industry) and urban sites. Hg releases to aquatic environments from these sites were then estimated based on the data available for selected case studies, their number, extent of contamination and geographic location (e.g. in the arid climate fluxes are less significant compared to those in more humid climate with the relief more prone to erosion). Summing up the contributions from all contaminates sites categories, at least 150 tons of Hg are released annually to the estuaries, with precious metal processing and Hg mining being the most important. Of that, ~15 tonnes Hg yr-1 reaches the open ocean. Apart from this, amount of Hg accumulated in coastal environments, based on the published data of historic and present Hg releases to the estuaries, is estimated at a few thousand tonnes (5-10). Overall, our current understanding of mercury releases to hydrosphere from contaminated sites indicates that these releases can be of paramount importance. Compared to atmospheric emissions, within the individual contaminated site category, mercury releases to aquatic environments from contaminated sites can be similar or even up to an order of magnitude higher.

RS13-O4 — 9:15-9:30
Authors: COELHO, João Pedro1, MIEIRO, Cláudia L1, PEREIRA, Maria E1, DUARTE, Armando C1, PARDAL, Miguel A2
(1) CESAM & University of Aveiro, jpcoelho@ua.pt; (2) CEF & University of Coimbra.

The main aim of this study was to ascertain the biomagnification processes in a mercury- contaminated estuary, The Ria de Aveiro, which for decades received mercury rich effluents from a chlor-alkali industry. Clarification of the trophic web structure was performed by means of stable isotope analyses (d15N and d13C), and trophic magnification factors (TMF) calculated for the area. For this purpose, primary producers (seagrass Zostera noltii and macroalgae Fucus vesiculosus, Gracilaria verrucosa, and Ulva sp.), invertebrates (detritivores Scrobicularia plana and Hediste diversicolor and predator Carcinus maenas) and fish (Liza aurata and Dicentrarchus labrax) where analysed for total and organic mercury, stable carbon and nitrogen isotopic signatures. Trophic structure was accurately described by d15N, while d13C reflected the carbon source for each species. Trophic levels calculations in the Ria de Aveiro food web were consistent with previous reports on the studied species, and allowed to discriminate between species that while occupying similar ecological niches, have distinct feeding tactics.

Mercury levels tended to increase with trophic level, confirming the magnification of mercury along the estuarine food web. This trend was observed especially for organic mercury forms, both in absolute concentrations and fraction of total mercury load. The slopes obtained for organic mercury data and trophic level (0.88) are considerably higher than usually reported in literature, suggesting elevated risk to top predators and humans, given the high magnification rates.

Time of exposure emerges as an important variable in metal magnification studies. The adjustment of mercury data to reflect the annual bioaccumulation instead of lifespan bioaccumulation provided considerable improvement in the regression coefficients found, while not influencing the slope. Time adjusted data will therefore provide a view of trophic magnification processes on an annual basis, as opposed to comparing species with completely different life cycles and exposure time to contaminants.

In addition, organic mercury concentrations seemed to follow a linear, rather than an exponential accumulation curve, reflected in the inferior regression coefficients observed for log-transformed data. Organic mercury fraction also displayed a significant linear regression with trophic level, which may justify, if confirmed as a general trend, an adaptation of trophic magnification methodologies to better describe organic mercury magnification processes.

RS13-O5 — 9:30-9:45
Authors: DAVIDSON, Christine. M1, KEENAN, Helen.E2, , GESAMP WG 373
(1) WestCHEM, Department of Pure and Applied Chemistry, University of Strathclyde, Glasgow, Scotland, UK, c.m.davidson@strath.ac.uk; (2) DLCS, University of Strathclyde, Glasgow, Scotland, UK; (3) GESAMP.

Improved understanding of the role of mercury as a global pollutant relies on the availability of accurate, reliable analytical methods to determine both total mercury concentration and, often more importantly, specific mercury species in environmental samples such as seawater, marine biota and sediment. Several instrumental analytical techniques are well established for measuring total mercury in aquatic samples and solid sample extracts, notably cold vapour atomic absorption spectrometry, atomic fluorescence spectrometry and inductively-coupled plasma mass spectrometry. However, there is less agreement on the best methods to use to extract analyte from solid samples prior to quantification, especially where the goal is to obtain not total, but species-specific information in order to estimate risk of mercury mobilisation or bioavailability. Numerous approaches are reported in literature [1, 2]. This lack of harmonised methodology means that different analysts may generate different results from the same samples, rendering impossible the comparison of data produced in different laboratories or countries and thus undermining attempts to implement a global strategy for the management of mercury. A further analytical challenge is the lack of suitable certified reference materials (CRMs) for use in validation of analytical methods, especially methods of speciation analysis. Although some are available, a wider range needs to be produced so that workers have available CRMs that closely match the samples studied in terms of their matrix composition and approximate pollutant concentrations. Finally, given the probably increase in numbers of samples to be analysed for their mercury content in the next decade, especially in developing countries where complex laboratory facilities may be limited or non-existent, there is a need for the development of simple, field-deployable methods of analysis. These can be used as screening test to gain rapid information on approximate mercury levels in samples. More complex and costly laboratory-based analyses can then be restricted to only those samples identified as of particular interest due, for example, to the presence of high analyte concentrations.

RS13-O6 — 9:45-10:00
Authors: CAVOURA, Olga1, KEENAN, Helen.E1, DAVIDSON, Christine.M1, KATSIRIS, Nicholas2
(1) University of Strathclyde, Glasgow, Scotland, olga.cavoura@strath.ac.uk; (2) Department of Sanitary Engineering and Environmental Health, National School of Public Health, Athens, Greece.

Implementation of a screening method for mercury in the marine environment for the identification of contaminated sediment followed by classification of mobility has been carried out in the Bay of Elefsis, one of the most industrialized areas in the Attica Region of Greece. With releases of mercury being both natural and anthropogenic, and sediment contamination resulting from surface water run off, discharge of industrial effluent, atmospheric deposition and from the aquatic environment itself, the extent of sediment mercury pollution is difficult to assess. Screening involving sample digestion, reduction of inorganic mercury to elemental mercury, and the trapping of elemental mercury on detecting papers with a copper iodide coating, to produce a colour the intensity of which is related to the mercury concentration in the sample has been implemented previously in soil and fresh water sediment [1]. This method was implemented in the marine environment. Marine sediment samples were obtained from the Gulf of Elefsis, both coastal and from the centre of the bay. Industrial discharges in the bay arise mainly from shipyards, steelworks and oil refineries. Coastal sampling points were selected in the region of two shipyards, two in the region of refineries, one from a ship disassembly unit, and one sampling point from an outlet that receives effluent from several industries such as asphalt and paper production. Three samples were also collected from the centre of the bay. Previous determinations of metal concentrations have indicated higher results for coastal regions, consistent with pollution directly as a result of main land industrial activity. Screening results indicate that total mercury concentrations in the majority of the samples exceed 0.1 mg/kg, the method detection limit. There is no agreed international limit value for mercury in sediment. However, subsequent quantification of the mercury concentration in the samples indicated that some exceed the Canadian sediment quality guideline value of 0.13 mg/kg for marine sediment. Determination of the mobility of mercury in the samples was carried out using sequential extraction, identifying mobile, semi mobile and non mobile species concentrations. The mobile fraction was further separated into organic and inorganic forms of mercury using solid phase extraction with sulphydryl cotton fibres [2].

RS13-O7 — 10:00-10:15
Authors: KEENAN, Helen.1, ŽAGAR, Dušan 2, SIRNIK, Nataša2, HORVAT, Milena3, KOCMAN, David3
(1) University of Strathclyde, h.e.keenan@strath.ac.uk; (2) University of Ljubljana; (3) Jožef Stefan Institute, Ljubljana;

Existing modelling techniques in contaminated coastal areas are being significantly improved in the framework of the EU FP7 project “Hydronet “. These techniques are used to (1) access and use the available data on hydrodynamics and oceanographic, meteorological and environmental parameters obtained with other models; (2) apply data on environmental parameters and pollutants measured in high spatial and temporal resolution by sensor-equipped autonomous floating buoys and robots. The model PCFLOW3D has been improved in order to (1) forecast water circulation in the areas under study in adequate spatial and temporal resolution, (2) simulate transport and fate of pollutants on the basis of measured and modelled input parameters and (3) perform nearly real-time short-term simulations.

PCFLOW3D is used for simulations of pollutant transport and transformations. It was improved by introducing several additional variables. With these, it is now possible to simulate more environmental parameters and to account for the impact of several new variables on mercury transformations. The Fasham’s nitrogen-based model for plankton dynamics (Fasham et al., 1990) will help determine nutrients and oxygen content in the water column. PCFLOW3D is currently set in different spatial resolutions for the two Hg-contaminated areas under study. In the Gulf of Trieste, the resolution in the horizontal plane is approx. 150x150 m and the layer thickness is 1 m, while in the Livorno coastal sea the horizontal resolution is 500x500 m with layers of various thickness (1 – 40 m).

In order to transform results of other models into input data for PCFLOW3D, several new interfaces had to be developed. Measured data from buoys and robots is transferred via web-interfaces from the AmI database to PCFLOW3D and the modelling results are fed back to the database. GIS models are applied to simulate conditions in the background areas and to determine river inputs.

Using all the described improvements and the significantly larger quantity and better quality of input data, we expect to increase the accuracy of mercury transport and transformations simulated with the PCFLOW3D model.

The research has received funding from the European Community’s Seventh Framework Programme FP7/2007-2013 (grant agreement n° 212790 – HYDRONET).

Fasham, M. J. R.; Ducklow, H. W.; McKelvie, S. M. (1990). "A nitrogen-based model of plankton dynamics in the oceanic mixed layer". Journal of Marine Research 48: 591-639.

RS13-O8 — 10:15-10:30
Authors: ALO, Babajide1, KEENAN, Helen. E1, , GESAMP WG 372
(1) , balo@unilag.edu.ng; (2) GESAMP.

This presentation is based on the summary of the GESAMP report to UNEP on mercury in the aquatic environment. The summary is divided into three main sections: Sources and releases, aquatic and oceanic transport and assessment of monitoring and evaluation. Sources can be natural or anthropogenic in origin with both diffuse and point sources being considered. While point sources are the most direct entry into an aquatic system, atmospheric deposition is the dominant input component to the world oceans. Consequently, reduction of mercury emissions must be the dominant mechanism of control. Wet deposition is a primary mechanism for transporting mercury from the atmosphere to surface water and land. Once in aquatic systems, it can exist in dissolved or particulate forms and can undergo a number of chemical transformations. Contaminated sediments at the bottom of surface waters serves as a mercury reservoir with sediment-bound mercury, recycling back into the aquatic ecosystem for decades or longer. Mercury has a long retention time in soils, so mercury that has accumulated in soils may continue to be released to surface waters and other media for long periods. Methylmercury (CH3Hg+)is the most common form of organic mercury in the environment and is more toxic than elemental or inorganic mercury with the potential for bioconcentration and bioaccumulation via the aquatic food web. This places people, all over the world, who consume predatory fish (or where fish is a dietary staple) at risk. The methylation of mercury occurs by biotic and abiotic processes, and transformation processes are influenced by several environmental factors such as pH, temperature, sulphate deposition, and availability of biodegradable organic carbon. Currently there are 2 main ways to evaluate concentrations of mercury in the environment based on principles of modelling or measuring techniques. Modelling programs have been studied to better understand the behaviour of substances in environmental media and used to estimate for mercury and its compounds in various environmental compartments. The advantages and disadvantages of modelling versus measuring techniques will be presented in full.

Thursday, 28 July, 2011