NIVA Open Access Archive
Not a member yet
8416 research outputs found
Sort by
Quantification of Riverbank Macroplastic Contamination in The Lower Citarum River
Get PDFPlastic waste generation has been increasing over the last decades. Rivers represent complex environments where plastics may be stored and remobilized. Studies on riverine plastic, including riverbank contamination, are still lacking. Riverbank surveys were carried out in the Citarum River, Indonesia, at three river sections in Purwakarta, Karawang, and Muara Gembong in March-April 2021. The aim was to quantify the abundance of plastic waste at different points in the riverbank zone. The sample 'monolith' was taken by digging a quadrat of 30x30x10 cm3. All material was then weighed. Three replicates along the length of the bank and three replicates across the bank were taken. The non-plastic fraction was weighed and its composition was estimated. Plastic fraction was classified into categories, counted, and weighed. The result show that plastic litter was found in all monolith ranging from 0.7-301 g of plastic litter per monolith. The largest proportion of plastic contaminant was found in Karawang with 2.85% of plastic in a single monolith and the largest average plastic contaminant was about 0.78% of the total monolith weight, showing that plastic contamination is prevalent. Enhancing waste management, reducing single-use plastics, and plastic recycling are recommended to tackle plastic contamination in the study area.publishedVersio
Gjenvekst av krypsiv etter tiltak, og effekter av kalking på krypsiv i Otra ved Rysstad
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 krypsiv vekst. Kartlegging av krypsiv i august 2021, det vil si cirka ett år etter at krypsiv ble fjernet i et utvalgt område og 4 mnd. etter at kalkingen startet, viser at (1) det kun var begrenset gjenvekst av krypsiv; dette tyder på at gjenveksten foregår sakte; og (2) kalkingen har hittil ikke hatt målbar effekt på krypsiv biomasse.publishedVersio
Tiltaksrettet overvåking av Glomma ved Borregaard 2021
Get PDFProsjektleder Maia Røst KileDenne rapporten presenterer årets resultater fra undersøkelser av biologiske og kjemiske forhold i Glomma ved Borregaard Fabrikker. Hensikten har vært å vurdere effekter av bedriftens utslipp på økologiske og kjemiske forhold i vassdraget fra 2015 til 2021, identifisere mulige tidstrender og undersøke rekruttering av laks. Prøver av bunnfauna, alger og heterotrof begroing tyder på at bedriftens utslipp påvirker nedre Glomma. Mens referansestasjonen oppstrøms Sarpsfossen varierer mellom god og moderat tilstand er samtlige stasjoner nedstrøms ett eller flere utslippspunkter i moderat eller dårlig økologisk tilstand. God kjemisk tilstand ble oppnådd på begge stasjoner som ble analysert for metaller. Estimert tetthet av laksunger (0+) på grusørene i 2021 var betydelig høyere enn tidligere år. Undersøkelse av fargemerking (settefisk) i et lite utvalg individer, antydet at naturlig reproduksjon i betydelig grad bidro til ungfiskpopulasjonen i 2021.publishedVersio
Towards improved waste management in Bago Region, Myanmar – An initial assessment - Baseline report
Get PDFProject Manager Hans Nicolai AdamThe baseline report draws on research carried out as part of the ‘Bago Waste’ project, led by NIVA, in the Bago Region of Myanmar. It provides an initial assessment of the waste management situation in Myanmar, with special reference to one of its administrative Regions (Bago). Findings are based on a literature review, field observations and interviews carried out since the start of the project in January 2020. We explore the waste governance system in Myanmar with respect to relevant national laws, policies and strategies, in addition to examining current waste management practices for collection, segregation, recycling and disposal. The report also delves into emerging trends in waste management on the global policy scene, as well as examining common policy approaches that drive the shift towards greater circularity. In conclusion, a was forward is sketched that ties together the reports findings.publishedVersio
Influence of dense macrophyte vegetation and total gas saturation on the performance of acoustic telemetry
Get PDFAcoustic telemetry is widely used as a method for high resolution monitoring of aquatic animal movement to investigate relationships between individual animals and their environment. In shallow freshwater ecosystem, aquatic macrophytes are common and their presence increases habitat complexity and baffles sound propagation. These properties may be likely to affect the performance of acoustic telemetry, however, to date this issue has received little attention, when studying the ecology of movements of fishes in and around the important macrophyte habitats. Here, we conducted a range-test study in a freshwater riverine ecosystem, with mass development of the aquatic macrophyte Juncus bulbosus (L.), to assess how dense macrophytes impact detection probability, detection range, and performance of a three-dimensional receiver positioning system. Supersaturation of gas frequently occurs at the study site as a by-product of upstream hydroelectric power generation and gave a unique opportunity to investigate how total gas saturation affects the performance of acoustic telemetry. We also investigated the influence of environmental conditions (i.e., day-of-year, time of day, average water level above J. bulbosus) on detection probability together with vertical position of transmitters and location inside or outside macrophytes. The detection probability and range were generally low for transmitters in and outside J. bulbosus stands, with mean hourly detection probabilities ranging from 1.18 to 5% and detection ranges between 17.26 m ± 0.74. The interaction between total macrophyte biomass and distance to receiver reduced the detection probability and detection range substantially. Detection probability further decreased with increasing total gas saturation, and transmitters positioned near the sediment and close to the surface also had lower detection probabilities compared to receivers in the middle of the water column. Finally, the low detection probability affected position estimates, where only 23% of the detections could be positioned using the average positioning estimation method and positional accuracy and precision were low ranging from 1.48 to 164.8 m and 0 to 50.1 m, respectively.publishedVersio
Vurdering av økologisk tilstand i Oslo-elvene 2021 - Undersøkelser av bunndyr i Alnavassdraget og Ljanselvavassdraget
Get PDFProsjektleder Tor Erik EriksenDenne rapporten omhandler bunndyrundersøkelser fra seks stasjoner i Alnavassdraget (Alnaelva og Fossumbekken/Tokerudbekken) og fem stasjoner i Ljanselvavassdraget (Ljanselva og Gjersrudbekken). Prøver av bunndyrsamfunn ble samlet inn vår og høst 2021, og økologisk tilstand vurdert på bakgrunn av Average Score Per Taxon indeks (ASPT). Tidstrender for økologisk tilstand på bakgrunn av ASPT er diskutert. Undersøkelsene viste at ingen av elvene som helhet oppfyller miljømålet om god økologisk tilstand. God økologisk tilstand (basert på vår- og høstprøver) ble kun oppnådd på den øverste stasjonen i Alna (ALN1). Øvrige stasjoner i Alnavassdraget viste moderat (ALN2) og svært dårlig tilstand (ALN3, ALN4, ALN5 og ALN6). I Ljanselvavassdraget ble det målt moderat tilstand på stasjon LJA1 og LJA2, dårlig på LJA3 og moderat på LJA4 og LJA5. De fallende ASPT-verdiene nedover i vassdragene ble reflektert gjennom redusert mangfold av EPT-taksa (døgnfluer, steinfluer og vårfluer) og økende dominans av tovinger, fåbørstemark og døgnfluer på bekostning av vårfluer og steinfluer. Endringer i bunndyrsamfunnene støttes av vannkjemiske målinger av næringssalter og bakterier (E. coli), som viser økende konsentrasjoner nedover i vassdragene. Langtidstrender for økologisk tilstand i vassdragene viser en svak bedring i siden slutten av 80-tallet. Det gjenstår fortsatt tiltaksarbeid i form av bedring av vannmiljøet før Ljanselva og spesielt Alna kan klassifiseres som elver med god økologisk tilstand.publishedVersio
Environmental impacts of the diver operated C disc to harvest sea urchins and for kelp restoration
Get PDFProject Manager Helena Kling MichelsenNIVA did a 2-day environmental evaluation of the diver operated suction device “C disc” constructed by C robotics. Because the C disc uses suction from a water pump to suck sea urchins from the seafloor, it will collect bycatch and may have some harmful effects on the seafloor. It can also be used for kelp restoration in northern-Norway. This survey tested the C disc at two sea urchin barren grounds around Tromsø (Ytre Kårvika, Kvalsundet and Berg, Balsfjord) in May 2021. Analysis of catch efficiency on target sea urchins, bycatch and effects on the sea floor using video transects and frame counts was done at both sites. About 81 – 89 % of the catch consisted of the target species sea urchins and the CPUE was on average 78 ind./min (61 – 96 ind./min). Of these 11 % were damaged by the C disc. Bycatch accounted for 11 and 19 % of the catch and reflected the local community consisting of mainly larger loose sitting organisms. There was little to no damage observed on bycatch organisms, except for barnacle and blue mussels. There was a reduction in loosely fastened organisms after using the C disc, and the most impacted organisms reflected the bycatch. If the bycatch is kept in sea water and returned to sea soon after capture, they are likely to survive. The survey is only representative for hardbottom sea urchin barrens in northern-Norway.publishedVersio
International Intercomparison of In Situ Chlorophyll-a Measurements for Data Quality Assurance of the Swedish Monitoring Program
Get PDFChlorophyll-a is an essential climate variable. Chlorophyll-a in situ measurements are usually used for the validation of satellite images. Previous intercomparisons have shown that there can be substantial differences between in situ laboratories. In order to shed light on these differences, we arranged international chlorophyll-a intercomparisons with eight participating laboratories during 1–2 July 2021. We performed two dedicated transects through Bråviken bay (NW Baltic proper) and sampled four stations in each transect along a chlorophyll-a gradient. We took three surface replicates per laboratory and per station, i.e., 24 samples per laboratory. The samples were filtered through Whatman GF/F filters, and filters were frozen in liquid nitrogen and distributed in dry ice to all laboratories together with chlorophyll-a standards. The results between labs compared quite well. The mean normalized bias (MNB) of the standard measurements ranged between −23% and +19% for all laboratories and −7% to +19% for the Baltic Sea laboratories compared to high-performance liquid chromatography. The MNB of the two Bråviken transects ranged between −23 and +17% for all laboratories (compared to the median of all spectrophotometric and fluorometric measurements) and between −2 and +17% for the Baltic Sea laboratories. On average, the chlorophyll-a concentrations measured by the fluorometric method were about 13% higher than those measured by spectrophotometry, and fluorometry samples tended to have more scatter. The largest uncertainties seem to be caused by variable storage and extraction methods and are not fully captured in this intercomparison. This is demonstrated by analyzing historical comparisons revealing very large uncertainties (root mean square difference (RMSD) up to 109% and bias up to 68%), possibly due to too low filtration volumes and due to different extraction and storage methods. Our recommendation is to flash-freeze samples in liquid nitrogen and store them at −80°C. After storage, they should be extracted and measured at room temperature within 6–24 h. Our results also indicate that ethanol is much more efficient in extracting Chl-a than acetone. Last but not least, we would like to point out that the uncertainties in measuring chlorophyll-a by satellite are now within the range of in situ data, as shown here by comparing the in situ results from this study with published remote sensing results from the literature.publishedVersio
Unified understanding of intrinsic and extrinsic controls of dissolved organic carbon reactivity in aquatic ecosystems
Get PDFDespite our growing understanding of the global carbon cycle, scientific consensus on the drivers and mechanisms that control dissolved organic carbon (DOC) turnover in aquatic systems is lacking, hampered by the mismatch between research that approaches DOC reactivity from either intrinsic (inherent chemical properties) or extrinsic (environmental context) perspectives. Here we propose a conceptual view of DOC reactivity in which the combination of intrinsic and extrinsic factors controls turnover rates and determines which reactions will occur. We review three major types of reactions (biological, photochemical, and flocculation) from an intrinsic chemical perspective and further define the environmental features that modulate the expression of chemically inherent reactivity potential. Finally, we propose hypotheses of how extrinsic and intrinsic factors together shape patterns in DOC turnover across the land-to-ocean continuum, underscoring that there is no intrinsic DOC reactivity without environmental context. By acknowledging the intrinsic–extrinsic control duality, our framework intends to foster improved modeling of DOC reactivity and its impact on ecosystem services.publishedVersio
Feltbasert kunnskap, metodikk og kriterier for økologisk kvalitet til et utvalg av marine naturtyper
Get PDFProsjektleder/Hovedforfatter Eli RindeVi kommer her med innspill til utvikling av metodikk og kriterier for kartlegging og fastsettelse av økologisk kvalitet til et utvalg av marine naturtyper basert på feltundersøkelser. De utvalgte naturtypene er ålegrasenger, sukkertareskog, muslingbunner (både blåskjellbunner og flatøstersbanker), helofytt-saltvannssumper og ruglbunner. Undersøkelsene av ålegrasenger og sukkertareskog hadde fokus på å identifisere eventuelle sesongvariasjoner i egenskaper knyttet til naturmangfold og tilstand. For alle naturtypene har vi basert på feltundersøkelsene og tidligere verdikriterier for naturmangfold, vurdert hvilke egenskaper som egner seg som primær- og sekundærvariabler for naturmangfold og tilstand. Ruglbunner ble undersøkt ved Vega (Nordland), og de øvrige naturtypene hovedsakelig i Oslofjorden. Blåskjellbanker ble undersøkte både i Oslofjorden, Sør-Norge og ved Vega.publishedVersio