Repeated environmental baseline survey at AF Miljøbase Vats in conjugation with the Ekofisk cessation EPRD project

In this study, the environmental contamination by AF Environmental Base Vats (AFEBV) was assessed before and after the facilities demolition activities in the Ekofisk cessation EPRD project. Seafloor debris and contaminant concentrations in soil, groundwater and fjord sediments were measured in 2015 and compared with similar data from the 2009 baseline study. ROV inspections found generally normal biological conditions of the algae and benthic animals but also much anthropogenic scrap at the seabed, although the amount has decreased by 2015 in comparison to 2009 as a result of clean-up operations. The survey revealed that soil in the ultimate vicinity of the base has become more contaminated with PAHs, metals and mercury in particular. The annual monitoring programme revealed peak concentrations in moss and soil samples in 2010, but subsequent actions to reduce spreading of dust from the working area have resulted in decreasing contaminant levels in both types of samples. Assessment of groundwater samples showed low levels of all contaminants, indicating that the impermeable deck at the base prevents contaminant transfer. Sediments collected in the fjord adjacent to the demolition plant showed PAH levels largely in class II, but one PAH component and TBT was in class IV. Similar findings of TBT and PAH have been reported before 2009 and no evidence was found for a consistent change in the level of these contaminant between 2009 and 2015. Levels of PCB7, mercury and other metals were generally low (class I) in sediment samples from all fjord stations.AF Offshore Deco

Utslipp til sjø – kan enkle modeller gi tilstrekkelig grunnlag for vurdering av spredning, fortynning og surhetsgrad?

Det forelå i 2016 ca. 2500 utslippstillatelser for utslipp til kystvann i Norge. Til tross for mange bestrebelser på å redusere utslippene må en forvente at en også i fremtiden må leve med betydelige utslipp til sjø. For at dette skal være akseptabelt må det bestrebes å redusere innholdet av forurensende stoffer i utslippsvannet og benytte utslippsarrangement som gir minst mulig skadelige effekter. For å få til det er det nødvendig å få kartlagt i hvilke dyp et utslipp vil innlagres og den videre fortynningen. Modeller er viktige verktøy for optimalisering av utslippsarrangementet for å minimalisere risikoen for skadelige effekter. 3D-modeller er kompliserte og mer tidkrevende å bruke enn 2D modeller og ikke alltid hensiktsmessige når det er behov for enklere vurderinger. Vi vil her gi eksempler på hvordan enkle 2D modeller og sporstoff-forsøket med et fargestoff har vært brukt som grunnlag for å bestemme spredning og fortynning av et utslipp. Vi vil også vise hvordan utslipp av syre og base kan påvirke pH i en resipient.publishedVersio

Response of marine benthic fauna to thin-layer capping with activated carbon in a large-scale field experiment in the Grenland fjords, Norway

A field experiment with thin-layer capping was conducted in the Grenland fjords, Norway, for remediation in situ of mercury and dioxin-contaminated sediments. Experimental fields at 30 and 95 m depth were capped with (i) powdered activated carbon (AC) mixed with clay (AC+cla`y), (ii) clay, and (iii) crushed limestone. Ecological effects on the benthic community and species-feeding guilds were studied 1 and 14 months after capping, and a total of 158 species were included in the analyses. The results show that clay and limestone had only minor effects on the benthic community, while AC+clay caused severe perturbations. AC+clay reduced the abundance, biomass, and number of species by up to 90% at both 30 and 95 m depth, and few indications of recovery were found during the period of this investigation. The negative effects of AC+clay were observed on a wide range of species with different feeding strategies, although the suspension feeding brittle star Amphiura filiformis was particularly affected. Even though activated carbon is effective in reducing sediment-to-water fluxes of dioxins and other organic pollutants, this study shows that capping with powdered AC can lead to substantial disturbances to the benthic community.publishedVersio

In vivo bioaccumulation of contaminants from historically polluted sediments - Relation to bioavailability estimates

Many contaminants are recalcitrant against degradation. Therefore, when primary sources have been discontinued, contaminated sediments often function as important secondary pollution sources. Since the management and potential remediation of contaminated marine sediments may be very costly, it is important that the environmental risks of contaminants present in these sediments and benefits of remediation are evaluated as accurately as possible. The objective of this study was to evaluate the bioavailability of common organochlorine contaminants and polycyclic aromatic hydrocarbons (PAHs) in selected polluted sediments from Norway by simple generic sorption models (free energy relationships), as well as by pore water concentration measurements. Furthermore, the aim was to predict bioaccumulation from these bioavailability estimates for comparison with in vivo bioaccumulation assessments using ragworm (Nereis virens) and netted dogwhelk (Hinia reticulata). Predicted biota-to-sediment accumulation factors (BSAFs) derived from pore water concentration estimates were in better agreement with the bioaccumulation observed in the test organisms, than the generic BSAFs expected based on linear sorption models. The results therefore support that site-specific evaluations of bioaccumulation provide useful information for more accurate risk assessments. A need for increased knowledge of the specific characteristics of benthic organisms, which may influence the exposure, uptake and elimination of contaminants, is however emphasized.acceptedVersio

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

Long-term response of marine benthic fauna to thin-layer capping with powdered activated carbon in the Grenland fjords, Norway

The Grenland fjords in Norway have a long history of contamination by large emissions of dioxins and mercury. As a possible sediment remediation method in situ, thin-layer capping with powdered activated carbon (AC) mixed with clay was applied at two test sites at 30 m and 95 m depth in the Grenland fjords. This study presents long-term effects of the AC treatment on the benthic community structure, i.e. nine years after capping. Capping with AC significantly reduced the number of species, their abundance and biomass at the two test sites, compared to uncapped reference sites. At the more shallow site, the dominant brittle star species Amphiura filiformis disappeared shortly after capping and did not re-establish nine years after capping. At the deeper site, the AC treatment also caused long-lasting negative effects on the benthic community, but some recovery was observed after nine years. Ecological indices used to assess environmental status did not capture the impaired benthic communities caused by the capping. The present study is the first documentation of negative effects of powdered AC on marine benthic communities on a decadal scale. Our results show that the benefits of reduced contaminant bioavailability from capping with AC should be carefully weighed against the cost of long-term detrimental effects on the benthic community. More research is needed to develop a thin-layer capping material that is efficient at sequestering contaminants without being harmful to benthic species.publishedVersio

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

Beslutningsgrunnlag og tiltaksplan for forurensede sedimenter i Gunneklevfjorden. Delrapport fra Aktivitet 4.Biotilgjengelighet av kvikksølv og dioksiner i sedimenter og effekter av behandling med aktivt kull

Denne rapporten beskriver 1)sedimentmiljøet i Gunneklevfjorden målt med elektroder, 2) målinger av utlekking og bioakkumulering av kvikksølv, metylkvikksølv og klororganiske forbindelser (HCB, OCS og PCDD/F) og 3)effekter av behandlinger med pulverisert og granulert aktivt karbon (AC). Elektrodemålingene viste betydelige antropogene effekter med uvanlig høy pH i flere av sedimentprøvene og uvanlig høye redokspotensialer på en stasjon lengst nord i fjorden. Elektrodemålingene indikerte også gode forhold for dannelse av metylkvikksølv i et område med vannplanter nær sydenden av fjorden. Det ble målt generelt høye arealspesifikke flukser av miljøgifter fra fjordens sedimenter. Sammenlignet med total utlekking fra sedimentene i østre, midtre og vestre deler av Grenlandsfjordene viste Gunneklevfjorden størst arealspesifikk utlekking av HCB og OCS, mens dypområdene i Frierfjorden (vestre fjordområde) ga høyest utlekking av dioksiner. Total utlekking fra sedimentene i Gunneklefjorden ble estimert til størrelsesorden 5-10% av total utlekking fra hele Grenlandsfjordområdet. Utlekkingen av kvikksølv, metylkvikksølv og klororganiske forbindelser ble redusert ved behandling både med pulverisert og granulert aktivt kull, men pulver ga klart bedre effekt enn granulat. Bioakkumuleringsforsøket ga sprikende resultater, mest sannsynlig på grunn av lite gunstige miljøforhold for forsøksorganismene

Vurdering av miljøeffekter av sjøvannsutslipp fra SO2 renseanlegg ved Hydro Karmøy

Hydro Aluminium planlegger en to-trinns utvidelse av aluminiumsverket på Karmøy. Bedriften slipper ut sjøvann med sulfitt (SO2) som tas opp fra røykgassene i en sjøvannsvasker (scrubber). Sulfitten løses i vann og danner svovelsyrling (H2SO3) som oksideres videre til svovelsyre (H2SO4). I denne prosessen reduseres pH og det forbrukes oksygen som tilføres fra luft eller sjøvann. Prosessen medfører også at sjøvannet som slippes ut i resipienten har høyere temperatur enn inntaksvannet. Det finnes ikke norske etablerte grenseverdier for effekter av pH, oksygen eller overtemperatur i sjøvann. I rapporten argumenteres det for at pH er styrende faktor og at en lokal endring på inntil 0,5 pH-enheter er akseptabelt kriterium for å oppnå tilstrekkelig sikkerhet mot uønskede effekter i resipienten. For å imøtekomme dette kriteriet må utslippet fra scrubberen fortynnes opp til 25x i resipienten. Fortynningsberegninger viste at en slik fortynning normalt oppnås i relativt kort avstand fra utslippspunktet. Alternative lokaliseringer av utslippene etter produksjonsutvidelsen er vurdert på grunnlag av disse vurderingene og etter prinsippene skissert i Miljødirektoratets utkast til veileder for innblandingssoner

Sedimentoppvirvling under reketråling i Eidangerfjorden juni 2008

Bunnsedimentene i Grenlandsfjordene inneholder miljøgifter og særlig da dioksiner. I Eidangerfjorden ble det i juni 2008 utført en studie av hvordan bunntråling etter reker virvler opp sedimenter og medfører spredning av forurensede partikler. Prosjektet var et samarbeid mellom NIVA, Stockholms Universitet og Sveriges Fiskeriverk Havsfiskelaboratoriet i Lysekil, og omfattet målinger av strømforhold ved bunnen, turbiditet, partikkelkonsentrasjon og partikkelstørrelse under bunntråling i to dager. Resultatene viste markert partikkelspredning til 15-18 m over bunnen og i en bredde på ca. 150 m. Mengde oppvirvlet dioksin kan beregnes til størrelsesorden 5-50 mg toksisitetsekvivalenter (TE) fra et tråltrekk som her ble studert. På årsbasis i størrelsesorden 300-2500 mgTE. Det meste vil resedimentere i Eidangerfjorden mens en mindre andel som er knyttet til små partikler kan spres til Langesundsfjorden. Det vil skje en desorpsjon av dioksin fra de oppvirvlede partiklene som kan føre til en økt konsentrasjon av løst dioksin til de bunn-nære vannmassene