The influence of permanently submerged macrophytes on sediment mercury distribution, mobility and methylation potential in a brackish Norwegian fjord

Embargo until 30 August 2019.Macrophytes are shown to affect the microbial activity in different aqueous environments, with an altering of the sediment cycling of mercury (Hg) as a potential effect. Here, we investigated how a meadow with permanently submerged macrophytes in a contaminated brackish fjord in southern Norway influenced the conditions for sulfate reducing microbial activity, the methyl-Hg (MeHg) production and the availability of MeHg. Historically discharged Hg from a chlor-alkali plant (60–80 tons, 1947–1987) was evident through high Hg concentrations (491 mg Tot-Hg kg− 1, 268 μg MeHg kg− 1) in intermediate sediment depths (10–20 cm) outside of the meadow, with reduced concentrations within the meadow. Natural recovery of the fjord was revealed by lower sediment surface concentrations (1.9–15.5 mg Tot-Hg kg− 1, 1.3–3.2 μg MeHg kg− 1). Within the meadow, vertical gradients of sediment hydrogen sulfide (H2S) Eh and pH suggested microbial sulfate reduction in 2–5 cm depths, coinciding with peak values of relative MeHg levels (0.5% MeHg). We assume that MeHg production rates was stimulated by the supply and availability of organic carbon, microbial activity and a sulfide oxidizing agent (e.g. O2) within the rhizosphere. Following this, % MeHg in sediment (0–5 cm) within the meadow was approximately 10 × higher compared to outside the meadow. Further, enhanced availability of MeHg within the meadow was demonstrated by significantly higher fluxes (p < 0.01) from sediment to overlying water (0.1–0.6 ng m− 2 d− 1) compared to sediment without macrophytes (0.02–0.2 ng m− 2 d− 1). Considering the productivity and species richness typical for such habitats, submerged macrophyte meadows located within legacy Hg contaminated sediment sites may constitute important entry points for MeHg into food webs.acceptedVersio

Atmospheric deposition and lateral transport of mercury in Norwegian drainage basins: A mercury budget for Norway

Project manager Hans Fredrik Veiteberg BraatenReduced atmospheric loading of mercury (Hg) can improve the environmental status of freshwaters and coastal ecosystems. Sparse data limit impact assessments of changes in atmospheric Hg on aquatic ecosystems. Here, a Hg budget is calculated for Norway by estimating fluxes of Hg in the environment. Atmospheric inputs (ca. 3.3 tonnes annually) are a factor 10 higher than riverine export to coastal areas, indicating considerable retention in soils and lakes. Environmental loading of Hg to surface waters was separated into headwater (=catchment) export of Hg and atmospheric Hg loadings, which were of similar size (0.2 to 0.3 tonnes), where atmospheric loadings were considered of higher certainty than headwater fluxes. Robust methods for estimations of headwater Hg export at the regional scale are lacking. Hg budgets for small headwater catchments are more reliable and valuable to assess the fate of atmospheric Hg, and the role of aquatic Hg retention. Continued monitoring of Hg in deposition, catchments, and rivers are needed to reduce uncertainties in environmental assessments, in addition to international collaboration.Norwegian Environment AgencypublishedVersio

Integrated Water Resources Management in Myanmar Ecology of Rivers, Lakes, and Reservoirs

Prosjektleder: Ingrid NesheimThis is the final report from output 1 of the IWRM project 2015-2024. The goal of the project was to implement a classification system for the ecological status of rivers and lakes in Myanmar like the EU Water Framework Directive. As the project was ended in 2021 due to the military coup in Myanmar, planned activities could not be finished. This report presents a summary of the ecological surveys and ecological status assessments in selected water bodies in Myanmar achieved within the project. The report should be read in conjunction with the other comprehensive publications from the project. Although the current political situation in Myanmar put a halt to our activities, the reports and scientific papers comprised in this project, in addition to transferred knowledge about freshwater ecology to selected staff and to one PhD student from Myanmar, have led to a set of recommendations that hopefully will be an impetus for future river and lake biomonitoring in Myanmar. As knowledge about the ecology of most of the many water bodies in Myanmar is still poor a much bigger number of freshwater ecologists need to be educated to achieve the goal of classifying their status and to find solutions for their improvement.The Norwegian embassy in Yangon, Myanmar Norwegian Ministry of Foreign Affairs, NorwaypublishedVersio

Forest harvest effects on mercury in streams and biota in Norwegian boreal catchments

acceptedVersio

Petroleum oil and mercury pollution from shipwrecks in Norwegian coastal waters

Embargo until 28 March 2019Worldwide there are tens of thousands of sunken shipwrecks lying on the coastal seabed. These potentially polluting wrecks (PPW) are estimated to hold 3–25 million t of oil. Other hazardous cargo in PPW includes ordnance, chemicals and radioactive waste. Here, we present and discuss studies on mercury (Hg) and oil pollution in coastal marine sediment caused by two of the > 2100 documented PPW in Norwegian marine waters. The German World War II (WWII) submarine (U-864) lies at about 150 m below the sea surface, near the Norwegian North Sea island of Fedje. The submarine is estimated to have been carrying 67 t of elemental Hg, some of which has leaked on to surrounding sediment. The total Hg concentration in bottom surface sediment within a 200 m radius of the wreckage decreases from 100 g/kg d.w. at the wreckage hotspot to about 1 mg/kg d.w. at 100 m from the hotspot. The second wreck is a German WWII cargo ship (Nordvard), that lies at a depth of ca. 30 m near the Norwegian harbor of Moss. Oil leakage from Nordvard has contaminated the bottom coastal sediment with polycyclic aromatic hydrocarbons (PAH). The findings from this study provide useful insight to coastal administration authorities involved in assessing and remediating wreck-borne pollution from any of the tens of thousands of sunken shipwrecks.acceptedVersio

Mercury–Organic Matter Interactions in Soils and Sediments: Angel or Devil?

Embargo until 02 January 2020Many studies have suggested that organic matter (OM) substantially reduces the bioavailability and risks of mercury (Hg) in soils and sediments; however, recent reports have supported that OM greatly accelerates Hg methylation and increases the risks of Hg exposure. This study aims to summarize the interactions between Hg and OM in soils and sediments and improve our understanding of the effects of OM on Hg methylation. The results show that OM characteristics, promotion of the activity of Hg-methylating microbial communities, and the microbial availability of Hg accounted for the acceleration of Hg methylation which increases the risk of Hg exposure. These three key aspects were driven by multiple factors, including the types and content of OM, Hg speciation, desorption and dissolution kinetics and environmental conditions.acceptedVersio

Mercury in the Barents region – River fluxes, sources, and environmental concentrations

Arctic rivers are receiving increased attention for their contributing of mercury (Hg) to the Arctic Ocean. Despite this, the knowledge on both the terrestrial release sources and the levels of Hg in the rivers are limited. Within the Arctic, the Barents region has a high industrial development, including multiple potential Hg release sources. This study presents the first overview of potential Hg release sources on Norwegian and Russian mainland draining to the Barents Sea. Source categories cover mining and metallurgy industry; historical pulp and paper production; municipal and industrial solid waste handling; fossil fuel combustion; and past military activities. Available data on Hg in freshwater bodies near the identified potential release sources are reviewed. Levels of Hg were occasionally exceeding the national pollution control limits, thereby posing concern to the local human population and wildlife. However, the studies were sparse and often unsystematic. Finally, we present new data of Hg measured in five Barents rivers. These data reveal strong seasonality in the Hg levels, with a total annual flux constituting 2% of the panarctic total. With this new insight we aspire to contribute to the international efforts of reducing Hg pollution, such as through the effective implementation of the Minamata Convention. Future studies documenting Hg in exposed Barents freshwater bodies are warranted.publishedVersio

Spatial and temporal trends of mercury in freshwater fish in Fennoscandia (1965-2015)

Source at http://hdl.handle.net/11250/2467116Mercury (Hg) emissions to the atmosphere cause elevated Hg levels in fish, even in many remote regions of the world. Here we present an extensive database of more than 50 000 measurements of Hg in fish, including 2 775 individual water bodies in Fennoscandia (Norway, Sweden, Finland, Russian part of Kola Peninsula) sampled between 1965 and 2015. The data have been analysed for spatial patterns and temporal trends, on raw and weight-adjusted data. The database presents a useful reference for assessment of impacts of environmental policy on Hg in freshwater fish (i.e. Convention on Long-Range Transboundary Air Pollution and The Minamata Convention on Mercury)

Improved environmental status : 50 years of declining fish mercury levels in boreal and subarctic Fennoscandia

Temporally (1965–2015) and spatially (55°–70°N) extensive records of total mercury (Hg) in freshwater fish showed consistent declines in boreal and subarctic Fennoscandia. The database contains 54 560 fish entries (n: pike > perch ≫ brown trout > roach ≈ Arctic charr) from 3132 lakes across Sweden, Finland, Norway, and Russian Murmansk area. 74% of the lakes did not meet the 0.5 ppm limit to protect human health. However, after 2000 only 25% of the lakes exceeded this level, indicating improved environmental status. In lakes where local pollution sources were identified, pike and perch Hg concentrations were significantly higher between 1965 and 1990 compared to values after 1995, likely an effect of implemented reduction measures. In lakes where Hg originated from long-range transboundary air pollution (LRTAP), consistent Hg declines (3–7‰ per year) were found for perch and pike in both boreal and subarctic Fennoscandia, suggesting common environmental controls. Hg in perch and pike in LRTAP lakes showed minimal declines with latitude, suggesting that drivers affected by temperature, such as growth dilution, counteracted Hg loading and food web exposure. We recommend that future fish Hg monitoring sampling design should include repeated sampling and collection of pollution history, water chemistry, fish age, and stable isotopes to enable evaluation of emission reduction policies

Mercury in boreal freshwater fish – factors and processes governing increasing concentrations

Det er den organiske formen av kvikksølv, metylkvikksølv, som står i sentrum for kvikksølvforskningen. Metylkvikksølv anrikes opp gjennom næringskjedene, så selv om vannet ikke inneholder mye kvikksølv kan fisk allikevel ha høye konsentrasjoner. Denne bioakkumuleringen er grunnen til at Norge, i likhet med mange andre land, har måttet innføre kostholdsråd for fisk. Noe av årsaken til de økte konsentrasjonene av kvikksølv i ferskvannsfisk er knyttet til humus. Humus er nedbrutt organisk materiale som tilføres innsjøene fra jordsmonnet, og som gjør vannet brunt. Kvikksølv bindes lett til humus, og fisk fra mørke innsjøer inneholder ofte mye metylkvikksølv. Mindre sur nedbør over Nord-Europa har bidratt til mer humus i innsjøene og dette påvirker nivåene av kvikksølv i innsjøene på flere måter. Metylkvikksølv produseres av bakterier som lever av humus i oksygenfrie miljøer, og økt tilførsel av humus bidrar slik trolig til økt dannelse av metylkvikksølv. En annen mekanisme trekker i samme retning. Metylkvikksølv brytes også ned av sollys. Når innsjøene blir mørkere av humus trenger ikke lyset like dypt ned i vannet. Dette kan føre til at nedbrytingen av metylkvikksølv reduseres med omtrent en femtedel i årene som kommer. I tillegg til slike humus-relaterte prosesser bidrar også andre biologiske faktorer til økt tilgjengelighet av metylkvikksølv for næringskjedene i innsjøene våre. Dette inkluderer graden av predasjon i en innsjø, endring av trofisk nivå og ulik habitatutnyttelse. For eksempel kan innsjøer med relativt lite fisk se ut til å ha en raskere oppkonsentrering av metylkvikksølv gjennom næringskjeden. Dette kan skyldes at organismer på lavere trofiske nivåer utsettes for svakere beitepress fra fisk og dermed lever lenger. Og jo lenger organismen lever, jo mer kvikksølv kan den rekke å akkumulere. Selv om utslippene av kvikksølv er betydelig redusert både i Norge og Europa, øker konsentrasjonene i våre levende omgivelser og i fisk. Så langt er det få indikasjoner på at kurvene flater ut. I tillegg til nye utslipp, vil kvikksølv lagret i jordsmonnet kunne påvirke vann og vassdrag i flere hundre år fremover. På lang sikt vil reduserte utslipp globalt, særlig gjennom internasjonale avtaler som Minamatakonvensjonen, bidra til reduserte nivåer i naturen. Minamatakonvensjonens hovedmål er redusert bruk og utslipp av kvikksølv, og ble undertegnet av 93 land i 2013. Avtalen er viktig også for Norge, fordi kvikksølv lett transporteres over store avstander via atmosfæren. Men hvordan og hvilken form kvikksølvpåvirkningen i naturen vil få i fremtiden, er et spørsmål bare lengre tidsserier og fortsatt forskningsinnsats fra flere fagmiljøer kan gi svar på