NIVA Open Access Archive
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Inferring heavy tails of flood distributions through hydrograph recession analysis
Get PDFFloods are often disastrous due to underestimation of the magnitude of rare events. Underestimation commonly happens when the magnitudes of floods follow a heavy-tailed distribution, but this behavior is not recognized and thus neglected for flood hazard assessment. In fact, identifying heavy-tailed flood behavior is challenging because of limited data records and the lack of physical support for currently used indices. We address these issues by deriving a new index of heavy-tailed flood behavior from a physically based description of streamflow dynamics. The proposed index, which is embodied by the hydrograph recession exponent, enables inferring heavy-tailed flood behavior from daily flow records, even of short length. We test the index in a large set of case studies across Germany encompassing a variety of climatic and physiographic settings. Our findings demonstrate that the new index enables reliable identification of cases with either heavy- or non-heavy-tailed flood behavior from daily flow records. Additionally, the index suitably estimates the severity of tail heaviness and ranks it across cases, achieving robust results even with short data records. The new index addresses the main limitations of currently used metrics, which lack physical support and require long data records to correctly identify tail behaviors, and provides valuable information on the tail behavior of flood distributions and the related flood hazard in river basins using commonly available discharge data.publishedVersio
Using a Bayesian Network Model to Predict Risk of Pesticides on Aquatic Community Endpoints in a Rice Field—A Southern European Case Study
Get PDFBayesian network (BN) models are increasingly used as tools to support probabilistic environmental risk assessments (ERAs), because they can better account for uncertainty compared with the simpler approaches commonly used in traditional ERA. We used BNs as metamodels to link various sources of information in a probabilistic framework, to predict the risk of pesticides to aquatic communities under given scenarios. The research focused on rice fields surrounding the Albufera Natural Park (Valencia, Spain), and considered three selected pesticides: acetamiprid (an insecticide), 2-methyl-4-chlorophenoxyacetic acid (MCPA; a herbicide), and azoxystrobin (a fungicide). The developed BN linked the inputs and outputs of two pesticide models: a process-based exposure model (Rice Water Quality [RICEWQ]), and a probabilistic effects model (Predicts the Ecological Risk of Pesticides [PERPEST]) using case-based reasoning with data from microcosm and mesocosm experiments. The model characterized risk at three levels in a hierarchy: biological endpoints (e.g., molluscs, zooplankton, insects, etc.), endpoint groups (plants, invertebrates, vertebrates, and community processes), and community. The pesticide risk to a biological endpoint was characterized as the probability of an effect for a given pesticide concentration interval. The risk to an endpoint group was calculated as the joint probability of effect on any of the endpoints in the group. Likewise, community-level risk was calculated as the joint probability of any of the endpoint groups being affected. This approach enabled comparison of risk to endpoint groups across different pesticide types. For example, in a scenario for the year 2050, the predicted risk of the insecticide to the community (40% probability of effect) was dominated by the risk to invertebrates (36% risk). In contrast, herbicide-related risk to the community (63%) resulted from risk to both plants (35%) and invertebrates (38%); the latter might represent (in the present study) indirect effects of toxicity through the food chain. This novel approach combines the quantification of spatial variability of exposure with probabilistic risk prediction for different components of aquatic ecosystems.publishedVersio
Sikringstiltak i Stokkbekken – effekter på vannkvalitet, bunndyr og fisk
Get PDFProsjektleder: Asle ØkelsrudNorges vassdrags- og energidirektorat (NVE) utførte sikringstiltak mot erosjon i ravinedaler med bekkeløp i kvikkleiresoner på Rødde i 2021 og 2022. Sikringsarbeidet inkluderte erosjonssikring av to bekker, Stokkbekken og Hørsdalsbekken. Sprengsteinen ble hentet fra et lokalt pukkverk på Sjøla, og besto i all hovedsak av lokal grønnstein. NIVA utførte, i 2022, en undersøkelse med formål om å kvantifisere mengden partikler, beskrive partikkelmorfologi, utlekking av nitrogen (nitrat/ammonium) og metaller, samt undersøke endringer i bunndyrsamfunnet og mulige fysiologiske skader på fisk. Resultatet indikerer at innslaget av sprengsteinpartikler utgjør en liten andel av den totale partikkelmengden på stasjon nedstrøms sikringsarbeid. Resultater både fra bekken og et forsøk på utlekking av nitrogen og metaller fra sprengstein, viser at konsentrasjonene avtar raskt nedstrøms, og utgjør liten risiko for toksiske effekter på fisk og bunndyr. Det var ingen tydelige effekter på fisk målt som hemoglobinverdier (proxy for oksygenopptak), avsetning av partikler på gjeller eller histopatologiske endringer på gjeller (mekaniske skader) på stasjon nedstrøms sikringsarbeid. Arbeidene med erosjonssikring i vassdragene vil trolig ha en forbigående effekt på bunndyrsamfunnene, hvor tidligere sikrede deler av bekken raskt koloniseres fra oppstrøms upåvirkede bekkestrekninger. Med bakgrunn i de innsamlede data, framstår effektene på bunndyr og fisk som følge av erosjonssikringen av Stokkbekken/Hørsdalsbekken som marginale og forbigående.Norges vassdrags- og energidirektorat (NVE)publishedVersio
Interlaboratory Comparison of Extractable Organofluorine Measurements in Groundwater and Eel (Anguilla rostrata): Recommendations for Methods Standardization
Get PDFResearch on per- and polyfluoroalkyl substances (PFAS) frequently incorporates organofluorine measurements, particularly because they could support a class-based approach to regulation. However, standardized methods for organofluorine analysis in a broad suite of matrices are currently unavailable, including a method for extractable organofluorine (EOF) measured using combustion ion chromatography (CIC). Here, we report the results of an international interlaboratory comparison. Seven laboratories representing academia, government, and the private sector measured paired EOF and PFAS concentrations in groundwater and eel (Anguilla rostrata) from a site contaminated by aqueous film-forming foam. Among all laboratories, targeted PFAS could not explain all EOF in groundwater but accounted for most EOF in eel. EOF results from all laboratories for at least one replicate extract fell within one standard deviation of the interlaboratory mean for groundwater and five out of seven laboratories for eel. PFAS spike mixture recoveries for EOF measurements in groundwater and eel were close to the criterion (±30%) for standardized targeted PFAS methods. Instrumental operation of the CIC such as replicate sample injections was a major source of measurement uncertainty. Blank contamination and incomplete inorganic fluorine removal may introduce additional uncertainties. To elucidate the presence of unknown organofluorine using paired EOF and PFAS measurements, we recommend that analysts carefully consider confounding methodological uncertainties such as differences in precision between measurements, data processing steps such as blank subtraction and replicate analyses, and the relative recoveries of PFAS and other fluorine compounds.publishedVersio
Effects of acidification on nitrification and associated nitrous oxide emission in estuarine and coastal waters
Get PDFIn the context of an increasing atmospheric carbon dioxide (CO2) level, acidification of estuarine and coastal waters is greatly exacerbated by land-derived nutrient inputs, coastal upwelling, and complex biogeochemical processes. A deeper understanding of how nitrifiers respond to intensifying acidification is thus crucial to predict the response of estuarine and coastal ecosystems and their contribution to global climate change. Here, we show that acidification can significantly decrease nitrification rate but stimulate generation of byproduct nitrous oxide (N2O) in estuarine and coastal waters. By varying CO2 concentration and pH independently, an expected beneficial effect of elevated CO2 on activity of nitrifiers (“CO2-fertilization” effect) is excluded under acidification. Metatranscriptome data further demonstrate that nitrifiers could significantly up-regulate gene expressions associated with intracellular pH homeostasis to cope with acidification stress. This study highlights the molecular underpinnings of acidification effects on nitrification and associated greenhouse gas N2O emission, and helps predict the response and evolution of estuarine and coastal ecosystems under climate change and human activities.publishedVersio
Tiltaksrettet overvåking av Glomfjorden i henhold til vannforskriften. Overvåking for Yara Norge AS Glomfjord
Get PDFProsjektleder: Camilla With FagerliNIVA har gjennomført tiltaksrettet overvåking i Glomfjorden for Yara Norge AS Glomfjord. Planteplankton, næringssalter og siktdyp ble undersøkt ved syv hydrografistasjoner. Betydelige algeoppblomstringer fant sted gjennom vår- og sommerperioden ved stasjonene nærmest industriutslippene fra Yara Glomfjord og MOWI og basert på konsentrasjon av klorofyll a viste stasjonenene nærmest utslippene «moderat» eller «dårlig» tilstand, mens tilstanden var «god» ved de to ytterste hydrografistasjonene med størst avstand til utslipp. For kvalitetselementet makroalger, er tilstanden «dårlig» til «moderat» for fem av åtte undersøkte stasjoner. Isskuring kan ha bidratt til lavere artsmangfold på stasjonene mens forhøyet andel med grønnalger ble registrert ved stasjoner nært utslippene kobles til høye næringsalttilførsler. Måleverdiene for nivåer av de radioaktive elementene U-nat, Th-nat og K-40 i sediment, blåskjell og sjøvann befinner seg innenfor det normale.Yara Norge ASpublishedVersio
Finding the Balance between Research and Monitoring: When Are Methods Good Enough to Understand Plastic Pollution?
Get PDFPlastic pollution is an international environmental problem. Desire to act is shared from the public to policymakers, yet motivation and approaches are diverging. Public attention is directed to reducing plastic consumption, cleaning local environments, and engaging in citizen science initiatives. Policymakers and regulators are working on prevention and mitigation measures, while international, regional, and national bodies are defining monitoring recommendations. Research activities are focused on validating approaches to address goals and comparing methods. Policy and regulation are eager to act on plastic pollution, often asking questions researchers cannot answer with available methods. The purpose of monitoring will define which method is implemented. A clear and open dialogue between all actors is essential to facilitate communication on what is feasible with current methods, further research, and development needs. For example, some methods can already be used for international monitoring, yet limitations including target plastic types and sizes, sampling strategy, available infrastructure and analytical capacity, and harmonization of generated data remain. Time and resources to advance scientific understanding must be balanced against the need to answer pressing policy issues.publishedVersio
Gjenvekst av krypsiv etter tiltak, og effekter av kalking på krypsiv i Otra ved Rysstad – oppdatert status 2022
Get PDFProsjektleder: Susanne C. SchneiderOtra ved Rysstad har i lang tid hatt utfordringer med massevekst av krypsiv. Mekanisk fjerning av krypsiv i utvalgte områder der plantene er til særlig sjenanse for fiske og bading blir sett på som det mest praktiske tiltaket, men det er ukjent hvor raskt krypsivet kommer tilbake etter tiltak. I tillegg er Otra ved Rysstad blitt kalket siden april 2021, og det er blitt uttrykt bekymring for at kalkingen kan føre til ytterlige vekst av krypsiv. Kartlegging av krypsiv i august 2022, det vil si cirka to år etter at krypsiv ble fjernet i et utvalgt område og ett år og 4 mnd. etter at kalkingen startet, viser at (1) to år etter tiltaket var krypsivbiomassen tilbake på omtrent samme nivå som før; og (2) kalkingen har hittil ikke hatt målbar effekt på dekningsgrad eller plantelengde av krypsiv, men førte til en markant økning i forekomst av flotgras, tjønnaks og tusenblad i Rysstadbassenget.Krypsiv på SørlandetpublishedVersio
Marine invasive alien species in Europe: 9 years after the IAS Regulation
Get PDFBiological invasions, resulting from human activities, exert substantial impacts on ecosystems worldwide. This review focuses on marine invasive alien species (IAS) in Europe, examining the current state, proposing strategies to address the problem, and offering recommendations for enhanced management. Effective management of biological invasions relies on accessible, accurate data to inform decision-making. Information systems such as the European Alien Species Information Network (EASIN), Aquatic Non-Indigenous and Cryptogenic Species (AquaNIS), and World Register of Introduced Marine Species (WriMS) provide comprehensive databases on IAS, but their sustainability requires long-term maintenance, continuous updates, and support. Most countries lack specific monitoring programs for marine IAS, and standardization and improvement of monitoring methods are needed. Port monitoring plays a vital role in the early detection of new arrivals, and recent advancements in molecular techniques show promise for effective IAS monitoring. Risk screening tools are commonly employed to rank taxa based on their invasiveness potential in European regions, but variations in protocols can yield inconsistent results. European impact assessments highlight resource competition, novel habitat creation, and predation as primary mechanisms for negative impacts on biodiversity, while the creation of novel habitats represents a key mechanism for positive impacts. Preventing IAS introductions is critical, and measures such as ballast water treatment systems are implemented to reduce the likelihood of marine introductions. However, understanding introduction pathways remains uncertain for many IAS. Eradication and control efforts for marine IAS have limited success, emphasizing the need for enhanced biosecurity measures. Climate change, especially ocean warming, can intensify IAS impacts on native species and ecosystems. In climate change hotspots, some tropical aliens may, however, compensate for the loss of thermally sensitive natives with similar traits. Therefore, it is imperative to consider the interactions between climate change and IAS in developing effective management and conservation strategies. Enhancing IAS management in Europe entails i) securing adequate funding, ii) expanding the list of IAS of Union Concern to adequately cover marine invasions, iii) learning from countries with successful biosecurity practices, iv) sustaining information systems, v) improving monitoring and early warning systems with innovative technologies, vi) enhancing prediction models, vii) conducting integrated impact assessments and mapping cumulative IAS impacts, and vii) considering the potential benefits of IAS in ecosystem functioning and services.publishedVersio
Tiltaksorientert overvåking av sjøområdet utenfor Stena Recycling avd. Skien i 2022.
Get PDFProsjektleder: Sigurd ØxnevadNIVA har i 2022 gjennomført tiltaksorientert overvåking av sjøområdet utenfor Stena Recycling avd. Skien. I overvåkingen er det gjort undersøkelser av miljøgifter i sediment på fire stasjoner og i utplasserte blåskjell på fire stasjoner. Det ble gjort analyser for miljøgiftene tungmetaller (arsen, bly, kadmium, kobber, krom, kvikksølv, nikkel og sink), polysykliske aromatiske hydrokarboner (PAH), polyklorte bifenyler (PCB), tetrabrombisfenol A, samt total mengde hydrokarboner (THC). Sedimentene utenfor Stena Recycling avd. Skien hadde i 2022 høyere konsentrasjoner av tungmetaller og organiske miljøgifter enn ved forrige undersøkelse (i 2007). Det var konsentrasjoner av kvikksølv, bly og kadmium som oversteg grenseverdiene for disse prioriterte stoffene. De fire sedimentstasjonene hadde også forhøyede konsentrasjoner av flere PAH-forbindelser. På grunn av overskridelser av grenseverdier for prioriterte stoffer blir kjemisk tilstand for sedimentstasjonene klassifisert som «ikke god». Det var generelt lave konsentrasjoner av både tungmetaller og organiske miljøgifter i blåskjellprøvene. Det var ingen konsentrasjoner i blåskjellene som oversteg grenseverdiene for kvikksølv og de fire PAH-forbindelsene som hører til de prioriterte stoffene i vannforskriften. Kjemisk tilstand for de fire blåskjellstasjonene klassifiseres derfor som «god». Det ser dermed ut til at miljøgiftene som finnes i ganske høye konsentrasjoner i sedimentene ikke er på en slik form at de tas opp i blåskjell.Stena Recycling avd. SkienpublishedVersio