NIVA Open Access Archive
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Marine primary producers in a darker future: a meta-analysis of light effects on pelagic and benthic autotrophs
Get PDFThe availability of underwater light, as primary energy source for all aquatic photoautotrophs, is (and will further be) altered by changing precipitation, water turbidity, mixing depth, and terrestrial input of chromophoric dissolved organic matter (CDOM). While experimental manipulations of CDOM input and turbidity are frequent, they often involve multiple interdependent changes (light, nutrients, C-supply). To create a baseline for the expected effects of light reduction alone, we performed a weighted meta-analysis on 240 published experiments (from 108 studies yielding 2500 effect sizes) that directly reduced light availability and measured marine autotroph responses. Across all organisms, habitats, and response variables, reduced light led to an average 23% reduction in biomass-related performance, whereas the effect sizes on physiological performance did not significantly differ from zero. Especially, pigment content increased with reduced light, which indicated a strong physiological plasticity in response to diminished light. This acclimation potential was also indicated by light reduction effects minimized if the experiments lasted longer. Nevertheless, the performance (especially biomass accrual) was reduced the more the less light intensity remained available. Light reduction effects were also more negative at higher temperatures if ambient light conditions were poor. Macrophytes or benthic systems were more negatively affected by light reduction than microalgae or plankton systems, especially in physiological responses were microalgae and plankton showed slightly positive responses. Otherwise, the effect magnitudes remained surprisingly consistent across habitats and aspects of experimental design. Therefore, the strong observed log–linear relationship between remaining light and autotrophic performance can be used as a baseline to predict marine primary production in future light climate.publishedVersio
Shifts in flood generation processes exacerbate regional flood anomalies in Europe
Get PDFAnomalies in the frequency of river floods, i.e., flood-rich or -poor periods, cause biases in flood risk estimates and thus make climate adaptation measures less efficient. While observations have recently confirmed the presence of flood anomalies in Europe, their exact causes are not clear. Here we analyse streamflow and climate observations during 1960-2010 to show that shifts in flood generation processes contribute more to the occurrence of regional flood anomalies than changes in extreme rainfall. A shift from rain on dry soil to rain on wet soil events by 5% increased the frequency of flood-rich periods in the Atlantic region, and an opposite shift in the Mediterranean region increased the frequency of flood-poor periods, but will likely make singular extreme floods occur more often. Flood anomalies driven by changing flood generation processes in Europe may further intensify in a warming climate and should be considered in flood estimation and management.publishedVersio
Bacterial bioindicators enable biological status classification along the continental Danube river
Get PDFDespite the importance of bacteria in aquatic ecosystems and their predictable diversity patterns across space and time, biomonitoring tools for status assessment relying on these organisms are widely lacking. This is partly due to insufficient data and models to identify reliable microbial predictors. Here, we show metabarcoding in combination with multivariate statistics and machine learning allows to identify bacterial bioindicators for existing biological status classification systems. Bacterial beta-diversity dynamics follow environmental gradients and the observed associations highlight potential bioindicators for ecological outcomes. Spatio-temporal links spanning the microbial communities along the river allow accurate prediction of downstream biological status from upstream information. Network analysis on amplicon sequence veariants identify as good indicators genera Fluviicola, Acinetobacter, Flavobacterium, and Rhodoluna, and reveal informational redundancy among taxa, which coincides with taxonomic relatedness. The redundancy among bacterial bioindicators reveals mutually exclusive taxa, which allow accurate biological status modeling using as few as 2–3 amplicon sequence variants. As such our models show that using a few bacterial amplicon sequence variants from globally distributed genera allows for biological status assessment along river systems.publishedVersio
Vurdering av utslippspunkt for nytt renseanlegg i Drammensfjorden
Get PDFProsjektleder: André StaalstrømDet planlegges å bygge et nytt sentralt renseanlegg i Drammen, og i denne rapporten har virkningen av utslippsdyp fra 30 til 90 m blitt vurdert. På grunn av økt vertikal blanding så vil oksygenforholdene i vannmassene bli bedre. Virkningen er best om utslippet slippes ut på 90 m dyp, men dette vil kreve at det bygges en 1,7-km lang avløpsledning. Det vil også være god effekt på oksygenforholdene om utslippet legges på 70-80 m som vil krev en betydelig kortere avløpsledning. Effekten av økte oksygenkonsentrasjoner over bunn vil virke positivt inn på miljøgifter i sedimentene ved at organiske stoffer brytes ned raskere og tungmetaller vil sedimentere raskere.Drammen, Asker og Lier kommunepublishedVersio
Sammenlignende laboratorieprøvninger (SLP) – Analyse av ferskvann. SLP 2331
Get PDFProsjektleder: Tina BryntesenUnder en sammenliknende laboratorieprøving (SLP) gjennomført i perioden februar – mai 2023 bestemte 35 laboratorier pH, konduktivitet, turbiditet, farge, UV-absorpsjon, natrium, kalium, kalsium, magnesium, hardhet, alkalitet, klorid, sulfat, fluorid, totalt organisk karbon, kjemisk oksygenforbruk (CODMn), fosfat, totalfosfor, ammonium, nitrat, totalnitrogen, aluminium, bly, jern, kadmium, kobber, krom, mangan, nikkel, sink, antimon og arsen. Prøvene ble laget ved å tilsette kjente stoffmengder til vann fra utløp av Krøderen (Krødsherad kommune) og utløp av Kråkefjorden (Sigdal kommune). Vannet var på forhånd filtrert gjennom membranfilter med porevidde 0,45 μm. Totalt ble 78 % av resultatene vurdert som akseptable, en andel som er noe lavere enn de seneste årene. Best resultater viser farge, aluminium (Al), kadmium (Cd), nikkel (Ni), sink (Zn) og antimon (Sb), med ≥ 90 % akseptert. De svakeste resultatene observeres for fluorid, nitrat og ammonium, med 50-57 % akseptert. Enkelte av parameterne opptrådte i lave konsentrasjoner eller hadde få deltakere som rapporterte resultater, og laboratoriene må ta hensyn til usikkerheten i "sann verdi" ved evalueringen av sine resultater.Norsk institutt for vannforskning (NIVA)publishedVersio
Sammenlignende laboratorieprøving (SLP) – Industriavløpsvann SLP 2363
Get PDFProsjektleder: Tina BryntesenVed en sammenlignende laboratorieprøving (SLP) arrangert i februar – mars 2023 deltok 68 laboratorier i bestemmelse av pH, suspendert stoff (tørrstoff og gløderest), sum organisk stoff (biokjemisk oksygenforbruk, kjemisk oksygenforbruk, totalt organisk karbon), totalfosfor, totalnitrogen og tolv metaller i syntetiske vannprøver. Ved denne SLPen, som har sitt utgangspunkt i Miljødirektoratets og fylkesmennenes kontroll med industriutslipp, er 83 % av resultatene ansett som akseptable. Kvalitetsnivået har over flere år holdt seg stabilt, med rundt 83-85 % akseptable resultater. De fleste parameterne viste en kvalitet som var sammenlignbar med de seneste SLPerNorsk institutt for vannforskning (NIVA)publishedVersio
Microfiber Hotspots’ Association with Ships in a Remote Port before and during Covid-19
Get PDFEmbargoed until 3. May 2024.During monthly water quality monitoring of Norwegian coastal waters, the sea surface waters off Brønnøysund, a remote port in Norway, exhibited an unexpectedly high abundance of microfibers. We further conducted monitoring of microplastics and microfibers from the surface waters off the city before and during the Covid-19 pandemic. Analysis of the microfiber characteristics, which were primarily comprised of cellulosic and polyester fibers, revealed similarities with those found in the global ocean, but at concentrations that were 1–4 orders of magnitude higher, with the maximum concentration reaching 491 n/L (0.34 mg/L). Source apportionment of microfibers using multivariate analyses based on simultaneous water chemistry data showed positive correlations with ships. Contrary to previous assumptions that marine microfibers were derived from land-based sources, our findings revealed that gray water discharge from ships significantly contributed to microfibers in the oceans. The demonstrated causations using path modeling between microfibers, gray water, shipping, and noncargo shipping activities call for urgent research and regulatory actions toward addressing plastic pollution in the UN Decade of Ocean Science.acceptedVersio
Removal of a cyanotoxins mixture by loose nanofiltration membranes applied in drinking water production
Get PDFCyanobacterial toxins may threaten human health if their levels in drinking water exceed certain thresholds. Therefore, it is important for water works that use raw water sources prone to cyanobacterial blooms to have efficient barriers against such toxins. Nanofiltration (NF) is one potential barrier. The efficacy and mechanism of removing four cyanotoxins, namely microcystins (MCs), cylindrospermopsin (CYN), saxitoxins (STXs), and anatoxin (ATX), were studied at bench-scale using NF membranes commonly applied in Norwegian drinking water facilities. The average removal of the different cyanotoxins under the tested operating conditions ranged from 15 % to 96 %. The membrane with the lowest molecular weight cut-off (MWCO) of 0.3 kDa made of polyamide (PA) was deemed the most suitable for the removal of all studied cyanotoxins. A gradual improvement of rejection observed with the 2 kDa cellulose acetate (CA) membrane was linked to the formation of fouling on the membrane surface. Sulfonated polyethersulfone (SPES) membranes with MWCO of 1 and 3 kDa could not efficiently and consistently remove cyanotoxins, except for MCs. The rejection of MCs over time was over 80 % by the SPES membranes during two days of filtration. The influence of pressure and pH as relevant operating parameters was evaluated. However, the analysis of the cyanotoxin concentrations in the permeate indicated that the investigated NF membranes alone would generally not be able to meet the WHO guidelines for drinking water during a severe cyanobacterial bloom. Thus, incorporating other water treatment technologies should be considered to effectively remove cyanotoxins.publishedVersio
The sensitivity of primary productivity in Disko Bay, a coastal Arctic ecosystem, to changes in freshwater discharge and sea ice cover
Get PDFThe Greenland ice sheet is melting, and the rate of ice loss has increased 6-fold since the 1980s. At the same time, the Arctic sea ice extent is decreasing. Meltwater runoff and sea ice reduction both influence light and nutrient availability in the coastal ocean, with implications for the timing, distribution, and magnitude of phytoplankton production. However, the integrated effect of both glacial and sea ice melt is highly variable in time and space, making it challenging to quantify. In this study, we evaluate the relative importance of these processes for the primary productivity of Disko Bay, west Greenland, one of the most important areas for biodiversity and fisheries around Greenland. We use a high-resolution 3D coupled hydrodynamic–biogeochemical model for 2004–2018 validated against in situ observations and remote sensing products. The model-estimated net primary production (NPP) varied between 90–147 gC m−2 yr−1 during 2004–2018, a period with variable freshwater discharges and sea ice cover. NPP correlated negatively with sea ice cover and positively with freshwater discharge. Freshwater discharge had a strong local effect within ∼ 25 km of the source-sustaining productive hot spots during summer. When considering the annual NPP at bay scale, sea ice cover was the most important controlling factor. In scenarios with no sea ice in spring, the model predicted a ∼ 30 % increase in annual production compared to a situation with high sea ice cover. Our study indicates that decreasing ice cover and more freshwater discharge can work synergistically and will likely increase primary productivity of the coastal ocean around Greenland.publishedVersio
Considerations for application of benchmark dose modeling in radiation research: workshop highlights
Get PDFExposure to different forms of ionizing radiation occurs in diverse occupational, medical, and environmental settings. Improving the accuracy of the estimated health risks associated with exposure is therefore, essential for protecting the public, particularly as it relates to chronic low dose exposures. A key aspect to understanding health risks is precise and accurate modeling of the dose-response relationship. Toward this vision, benchmark dose (BMD) modeling may be a suitable approach for consideration in the radiation field. BMD modeling is already extensively used for chemical hazard assessments and is considered statistically preferable to identifying low and no observed adverse effects levels. BMD modeling involves fitting mathematical models to dose-response data for a relevant biological endpoint and identifying a point of departure (the BMD, or its lower bound). Recent examples in chemical toxicology show that when applied to molecular endpoints (e.g. genotoxic and transcriptional endpoints), BMDs correlate to points of departure for more apical endpoints such as phenotypic changes (e.g. adverse effects) of interest to regulatory decisions. This use of BMD modeling may be valuable to explore in the radiation field, specifically in combination with adverse outcome pathways, and may facilitate better interpretation of relevant in vivo and in vitro dose-response data. To advance this application, a workshop was organized on June 3rd, 2022, in Ottawa, Ontario that brought together BMD experts in chemical toxicology and the radiation scientific community of researchers, regulators, and policy-makers. The workshop’s objective was to introduce radiation scientists to BMD modeling and its practical application using case examples from the chemical toxicity field and demonstrate the BMDExpress software using a radiation dataset. Discussions focused on the BMD approach, the importance of experimental design, regulatory applications, its use in supporting the development of adverse outcome pathways, and specific radiation-relevant examples.publishedVersio