Statistisk analyse av volum av forurenset sediment i Borg 1 og Flyndregrunnen, basert på samlet kjemisk analysemateriale fram til 2017

Prosjektleder Dag Øystein HjermannDet er foretatt statistiske beregninger av volummengden av forurenset sediment i området Røsvikrenna (nordligste del av leden til Borg havn, tiltaksområde Borg 1) samt Flyndregrunnen (den nordligste grunna i tiltaksområde Borg 2). Beregningene er basert på 620 prøver (seksjon av kjerneprøve eller overflateprøve) fra Røsvikrenna og 95 prøver fra Flyndregrunnen som er analysert kjemisk. Volumberegningen er gjort for ulike konfidensnivåer, der konfidens er definert ut fra andelen av sediment klassifisert som ikke-forurenset som i realiteten kan være forurenset. For Borg 1 er mengden forurenset sediment teoretisk beregnet til ca. 573 000 m3 (dersom en velger et konfidensnivå på 80 %) eller 757 000 m3 (dersom en velger et konfidensnivå 95 %). Beregninger fra Van ‘t Hoff Consultancy viser at de tilsvarende praktiske volumene, dvs. de massene som i praksis må behandles som forurenset, er estimert til 699 000 m3 (for konfidensnivå 80 %) eller 917 000 m3 (for konfidensnivå 95 %). For Flyndregrunnen er mengdene forurenset sediment beregnet til et teoretisk volum på ca. 39 000 m3 (for konfidensnivå 80 %) eller 42 000 m3 (konfidensnivå 95 %). Volumene med forurenset sediment er kartlagt og vises som konturer i kart laget for hver 10 cm dybde for begge konfidensnivåer.Rambøll Norge ASpublishedVersio

Effect of pooled sampling in the MILFERSK program

Prosjektleder: Morten JartunThe MILFERSK monitoring program is studying the occurrence and biomagnification of contaminants in freshwater ecosystems, mainly Lake Mjøsa. For the last 10 years, individual samples of muscle and liver from brown trout have been analyzed for a wide range of environmental contaminants. In this report we are statistically evaluating the effect of converting to pooled samples, i.e., 5 individuals constituting one composite sample. Main results indicate that analyzing pooled samples could mask or hide extreme concentrations, limiting the possibility to detect early occurrence in the environment. The statistical power will be weaker when studying biomagnification potential and time series, as fewer data points are included in the statistical models.MiljødirektoratetpublishedVersio

Do benthic algae provide important information over and above that provided by macrophytes and phytoplankton in lake status assessment? – Results from a case study in Norway

To test if phytobenthic algae provide additional important information to macrophytes and phytoplankton for lake monitoring, we sampled two large lakes in Norway. In each lake, we analyzed water chemistry and phytoplankton above the deepest site, recorded macrophytes and non-diatom phytobenthic algae at 20 sites around the shoreline and estimated site-specific nutrient input from land cover. Since no ready-to-use phytobenthos index exists for lakes in Norway, we tested the PIT index developed for rivers, commonly perceived signs of disturbance such as high algal cover, and taxon richness as well as similarity patterns. Both lakes were nutrient poor, but had potential local nutrient inputs (villages, agriculture). In neither of the lakes did phytobenthos indicate a worse overall ecological status than macrophytes and phytoplankton. Our data therefore, did not suggest that it would be useful to add phytobenthos into surveillance monitoring of lakes in Norway. There was a loose correlation between macrophyte and phytobenthic site-specific taxon richness and similarities. This means that macrophytes and phytobenthos do indeed give partly redundant information. High algal cover was found at sites with both high and low phosphorus input. Using algal cover as indicator of site-specific nutrient input is therefore overly simplistic. Urban and cultivated areas were associated with a more eutrophic PIT. This indicates that the PIT, despite being developed for lotic waters, may be used to detect site specific nutrient input in lakes.publishedVersio

Environmental effects of offshore produced water discharges: A review focused on the Norwegian continental shelf

Produced water (PW), a large byproduct of offshore oil and gas extraction, is reinjected to formations or discharged to the sea after treatment. The discharges contain dispersed crude oil, polycyclic aromatic hydrocarbons (PAHs), alkylphenols (APs), metals, and many other constituents of environmental relevance. Risk-based regulation, greener offshore chemicals and improved cleaning systems have reduced environmental risks of PW discharges, but PW is still the largest operational source of oil pollution to the sea from the offshore petroleum industry. Monitoring surveys find detectable exposures in caged mussel and fish several km downstream from PW outfalls, but biomarkers indicate only mild acute effects in these sentinels. On the other hand, increased concentrations of DNA adducts are found repeatedly in benthic fish populations, especially in haddock. It is uncertain whether increased adducts could be a long-term effect of sediment contamination due to ongoing PW discharges, or earlier discharges of oil-containing drilling waste. Another concern is uncertainty regarding the possible effect of PW discharges in the sub-Arctic Southern Barents Sea. So far, research suggests that sub-arctic species are largely comparable to temperate species in their sensitivity to PW exposure. Larval deformities and cardiac toxicity in fish early life stages are among the biomarkers and adverse outcome pathways that currently receive much attention in PW effect research. Herein, we summarize the accumulated ecotoxicological knowledge of offshore PW discharges and highlight some key remaining knowledge needs.publishedVersio

Tiltaksorientert overvåking av Årdalsfjorden i 2023. Overvåking for Hydro Aluminium Årdal

Prosjektleder: Sigurd ØxnevadNIVA har utført tiltaksorientert overvåking av Årdalsfjorden i 2023 på oppdrag for Hydro Aluminium Årdal. I overvåkingen er det gjort analyser av polysykliske aromatiske hydrokarboner (PAH-forbindelser), fluorid og tungmetaller (arsen, bly, kadmium, kobber, krom, kvikksølv, nikkel og sink) i prøver av blåskjell fra fire stasjoner. Det var høye konsentrasjoner av PAH-forbindelser i blåskjellene fra Hundshammar. Dette er stasjonen som ligger nærmest utslippspunktene innerst i fjorden. Det var overskridelse av miljøkvalitetsstandardene (EQS) for benzo(a)pyren og fluoranten i blåskjellene fra Hundshammar. Kjemisk tilstand for stasjonen Hundshammar klassifiseres derfor som «ikke god». De andre stasjonene var i «god» kjemisk tilstand. Konsentrasjoner av benzo(a)pyren og fluoranten over grenseverdiene innebærer at det er en risiko for sekundær forgiftning i dyr som spiser blåskjell. Selv om det var forhøyede konsentrasjoner av benzo(a)pyren og fluoranten i blåskjellene fra Hundshammar, så er det likevel en god utvikling med nedadgående konsentrasjon av disse prioriterte stoffene siden 2017.Hydro Aluminium ÅrdalpublishedVersio

Tiltaksorientert overvåking av Husebybukta på Lista i 2023. Overvåking for Alcoa Norway AS avd. Lista

Prosjektleder: Sigurd ØxnevadNIVA har utført tiltaksorientert overvåking av Husebybukta på Lista i 2023 på oppdrag for Alcoa Norway AS avd. Lista. Overvåkingsprogrammet er utarbeidet i henhold til vannforskriften og godkjent av Miljødirektoratet. Programmet er utformet på bakgrunn av bedriftens utslippskomponenter til sjøen. I overvåkingen er det gjort bestemmelser av PAH-forbindelser, arsen, bly, kadmium, kobber, krom, kvikksølv, nikkel, sink og fluorid i prøver av albusnegl fra fem stasjoner og blåskjell fra to stasjoner. Overvåkingen i 2023 viser at albusnegl og blåskjell samlet inn i Husebybukta på Lista hadde konsentrasjoner av PAH-forbindelsene benzo(a)pyren og fluoranten som ga overskridelse av grenseverdi for disse prioriterte stoffene. Kjemisk tilstand for stasjonene Haugestranda, Tjuvholmen og Grønnodden klassifiseres derfor som «ikke god». Det var ingen konsentrasjoner av prioriterte stoffer i albusnegl på de tre andre stasjonene som ga overskridelse av grenseverdier. Kjemisk tilstand for stasjonene Einarsneset, Havik og Østhassel klassifiseres derfor som «god».Alcoa Norway AS avd. ListapublishedVersio

Optimal age- and gear-specific harvesting policies for North-East Arctic cod

We examine optimal harvest policies in a multi-cohort, multi-gear bioeconomic model of North-East Arctic cod (Gadus morhua) which includes cannibalism and contains broader ecosystem effects. By controlling the selectivity of the different fishing equipment, we can partially target different age cohorts. We show that current gear selectivity implies that the wrong fish are targeted. Optimization shifts the exploitation pattern towards older and heavier fish. This increases the harvested biomass while reducing the number of fish removed from the ocean. The result is a much more robust and abundant cod stock with an age/size distribution closer to the stocks natural state. We optimize the Net Present Value (NPV) generated by the fishery by letting effort and selectivity be the control variables and find that NPV may be more than doubled, even when only gear selectivity or harvest effort is allowed to vary. (141 words

ESPIAL - Data review and evaluation of historical data (WP1)

Prosjektleder Ailbhe MackenThe present report details the outcome of work package 1 of ESPIAL, with the aim of compiling the historical data from previous surveys at the aluminium sites in a common database and further to analyse the data. A graphical data displaying tool was developed as a custom interactive tool for data visualisations and was designed to be intuitive and user friendly. The main outcomes and findings of this work package can be summarized as follows: Polycyclic aromatic hydrocarbons (PAHs) constitute most data in the database; There is a decent amount of data on sediment samples in the data base, however these do not form time series; Most time series available in the data base are on blue mussel from Sunndal and northern horsemussel from Årdal; Most time series show a declining tendency; All statistically significant PAH time trends show declining concentrations; The database is likely not complete, and more data could be available; The graphical data displaying tool is a promising aid for instant insight in concentrations and time series of different analytes in environmental samples, historically collected in the vicinity of the smelters; The graphical data displaying tool makes it possible to view concentrations and trends in relation to the EQSs, giving insight in chemical status and sites of interest, in terms of possible need of remedial action or natural recovery.Aluminiumindustriens Miljøsekretariat (AMS)publishedVersio

Non-cooperative exploitation of multi-cohort fisheries — the role of gear selectivity in the North-East Arctic cod fishery

North-East Arctic cod is shared by Russia and Norway. Taking its multi-cohort structure into account, how would optimal management look like? How would non-cooperative exploitation limit the obtainable profits? To which extent could the strategic situation explain today’s over- harvesting? Simulation of a detailed bio-economic model reveals that the mesh size should be significantly increased, resulting not only in a doubling of economic gains, but also in a biologi- cally healthier age-structure of the stock. The Nash Equilibrium is close to the current regime. Even when effort is fixed to its optimal level, the non-cooperative choice of gear selectivity leads to a large dissipation of rents