S13 Mercury in the marine environment and transboundary indicators

Thursday, 28 July, 2011

RS13-P1 — 11:00-12:00 and 17:30-18:30
Authors: DUNCAN, Derek1, KEENAN, Helen. E1, WG37, GESAMP2
(1) University of Strathclyde, derek.duncan@strath.ac.uk; (2) GESAMP.

A wide range of predictive models have been developed to better understand the fate and transport of mercury throughout the environment. This work collates some of the most accepted forms that are openly available for research purposes. Many of these have been developed and updated through progressive adaptation. While predictive models often analyse the intrinsic chemical and physical properties of mercury species in individual environmental compartments and matrices, such as those documented for atmosphere, water, land and biota, others have been developed for multimedia application.

The study of environmental mercury is highly complex and requires different approaches and technologies to further enhance understanding of processes and pathways. Models therefore play an essential role in comprehending mercury behaviour and cycling, uptake, bioaccumulation and biomagnification. Effective modelling enhances human and ecosystem risk assessments by anticipating transformations and exposures to the various forms of mercury that can influence such parameters as bioavailability and toxicity. However, since there are always margins of uncertainty inherently associated with estimated data, model outputs should be interpreted as representative rather than empirical. A compilation of models will be presented.

RS13-P2 — 11:00-12:00 and 17:30-18:30
Authors: RAGONE, Alba1, KEENAN, Helen. E1
(1) University of Strathclyde, alba.ragone@strath.ac.uk

Can Mercury be used as global indicators for the Trans-boundary Waters Assessment Programme ? (TWAP)

The basis of this project was to collect research data for Mercury, from the sixty-four Large Marine Ecosystems (LMEs), as well as from Open Oceans; the data for integration can be found in global database archives-environment monitoring programmes, such as government organisations, non-government organization, scientific reports and articles. The need to collect data on Mercury Pollution from Anthropogenic and Natural sources is required for establishing baselines and global trends in Large Marine Ecosystems and Open Oceans. Research indicates that Pollution is often trans-boundary as hydrological inter-linkages between River basins, Marine Ecosystems, and the Atmosphere have resulted in effects far away from the sources of emission. Pollution caused by Anthropogenic sources is of global concern and it is believed that population growth, mobility and an increasing need for goods and services, exacerbated Mercury pollution effects in a global scale. Mercury has the potential as a global indicator in the Trans-boundary Assessment Programme, however, further developments in data are necessary.

RS13-P3 — 11:00-12:00 and 17:30-18:30
Authors: TORRANCE, Keith1, KEENAN, Helen. E2, MUNK, LeeAnn3, HAGEDORN, Birgit4
(1) DLCS, University of Strathclyde, keith.torrance@strath.ac.uk; (2) University of Strathclyde; (3) University of Anchorage, Alaska; (4) University of Achorage, Alaska.

The Black Butte mercury mine near Cottage Grove, Oregon has recently been added to the Federal Clean Up List (2010). Water samples were collected from streams within the site and analysed for trace metals. Water samples were separated in the field into As(III) and As(IV) species for subsequent measurement using ICP-MS. Tailing piles on the mine site originating from the retort furnace contain cinnabar (HgS) up to 20mg kg-1, as measured using XRF, which has previously been established as the source of mercury polluting the adjacent Coast Fork Willamette River and Cottage Grove reservoir. Mercury methylation is largely confined to lake sediments with fish consumption advisories in effect.

The andesitic lavas hosting the mercury ores at Black Butte are naturally elevated in arsenic, with groundwater from wells in the region reported above the EPA MCL level of 10µg L-1.Arsenic levels in streams within the study area ranged from 0.3 – 9.6µg L-1. The highest levels were found in water flowing from the main mine adit. Over 80% of soluble arsenic is in the form of As(III), rather than As(V); this reflects the greater mobility of As(III) species. Dissolved mercury concentrations from site run-off are below detection limits; most of the mercury transportation is as sediment. Relationships between arsenic speciation and the mercury content of sediments are discussed.

RS13-P4 — 11:00-12:00 and 17:30-18:30
Authors: LEANER, Joy 1, KEENAN, Helen. E2, , GESAMP WG 373
(1)GESAMP Working Group 37, jleaner@pgwc.gov.za; (2) GESAMP Chair Working Group 37; (3) GESAMP.

It has been widely reported that methylation of mercury (Hg) into its toxic methylmercury (MeHg) form occurs by biotic and abiotic processes, and that the transformation processes are influenced by several factors such as pH, temperature, sulphate deposition, and availability of biodegradable organic carbon. Although the marine environment acts as a sink for Hg and its compounds, it is probably one of the least understood in terms of Hg transformation processes and its bioavailability and bioaccumulation in biota. This paper reviewed the pathways of Hg in terms of its speciation, uptake and transport in the marine environment and associated biota. The review indicates a paucity of data on Hg in the marine environment. As can be expected piscivorous predators in the marine environment have relatively higher MeHg concentrations in blood than non-piscivorous animals in the terrestrial environment. A comparison of Hg exposure and impacts in New Zealand, Seychelles and the Faroe Island is also made, and recommendations for further research in the marine environment are presented.

RS13-P5 — 11:00-12:00 and 17:30-18:30
Authors: CAVOURA, Olga 1, CAMPBELL, Erin 2, DAVIDSON, Christine.M2, KEENAN, Helen.E1
(1) David Livingston Centre for Sustainability, Department of Civil Engineering, University of Strathclyde, Glasgow, Scotland, UK, olga.cavoura@strath.ac.uk; (2) WestCHEM, Department of Pure and Applied Chemistry, University of Strathclyde, Glasgow, Scotland, UK;

There is considerable current interest in the development of simple, cheap analytical approaches for measuring potentially toxic metals and organometallics in the environment, especially methods that are field-deployable and that can be used by individuals with no scientific training. Amongst the simplest of these are paper-based sensors [1]. These test strips are analogous to litmus paper in that they are impregnated with reagent(s) that change colour on exposure to a specific pollutant, the intensity of which can be estimated ‘by-eye’ or read out by an electronic device, and relates to the pollutant concentration present. Key analytical challenges in the development of such sensors include ensuring that they are selective, sensitive and stable. Such a method has recently been reported for mercury involving reduction of inorganic mercury to elemental mercury and trapping on detecting papers with a copper iodide coating [2]. A preliminary sample digestion procedure is added for the determination of analyte in solid samples. The approach – which has been implemented previously in soil and fresh water sediment – is here evaluated for its applicability in the marine environment. Sensitivity and reproducibility were tested in distilled water, artificial seawater of different salinities, and in real environmental samples. Distinctions could be observed between the responses of solutions whose concentrations differed by at least 20 mg L-1 over a range from 15 – 100 mg L-1, and whose concentrations differed by at least 50 mg L-1 in the range from 100 – 250 mg L-1. The effective detection limit was ~ 15 mg L-1. Salinity ranging from 0-40 psu did not appear to affect significantly the response of the method. The procedure was applied as a screening analysis to provide a preliminary estimate of levels of mercury in contaminated marine sediment obtained from the Gulf of Elefsina, Greece. Sediment samples containing > 100 ng/g mercury were successfully identified, as confirmed by cold vapour atomic absorption spectroscopy.

RS13-P6 — 11:00-12:00 and 17:30-18:30
Authors: WITT, Melanie1, SKOV, Henrik2, BROOKS, Steve3, HENDERSON, Gideon1, MATHER, Tamsin1, CORNS, Warren4, PYLE, David 1
(1) University of Oxford, melaniew@earth.ox.ac.uk; (2) Arhus University; (3) NOAA/ARL; (4) PSAnalytical;

Despite the importance of the global biogeochemical Hg cycle, only sparse data are available regarding the distribution of mercury in the remote atmosphere in the southern hemisphere and there is currently extremely limited data for Hg levels in the Southern Atlantic open ocean and water columns in the open ocean. Studies on Hg levels in the open ocean suggest Hg is present at very low concentrations (fM-pM) and is subject to a complex biogeochemical cycling. In order to better understand the distribution of mercury in and over remote oceans, measurements were carried out during October/November 2010 in the South-eastern Atlantic Ocean on board the RRS Discovery as part of the GEOTRACES project. Atmospheric measurements were also carried out for several days while in port in Cape Town, South Africa.

Semi-continuous measurements were made of atmospheric Hg, speciated as elemental and reactive gaseous Hg (RGM), to investigate how the environment is responding to changing emissions of Hg from anthropogenic processes. The inclusion of RGM in the atmospheric measurements along with surface measurements of Hg give a better insight into how Hg cycles between the ocean and atmosphere.

Atmospheric mercury showed a decrease with increasing distance from South Africa. Full depth profiles have been collected to look for the distribution of Hg in the different water masses through the S Atlantic. Comparison of our measurements of Hg in the ocean with other measurements in the water column (e.g., organic biomarkers) and known sources of chemical species to the oceans across the transect (e.g. sediments at the continental margins) will allow us to build up a greater understanding of Hg behaviour in the water column.

Thursday, 28 July, 2011