Publikasjoner
NIBIOs ansatte publiserer flere hundre vitenskapelige artikler og forskningsrapporter hvert år. Her finner du referanser og lenker til publikasjoner og andre forsknings- og formidlingsaktiviteter. Samlingen oppdateres løpende med både nytt og historisk materiale. For mer informasjon om NIBIOs publikasjoner, besøk NIBIOs bibliotek.
2007
Forfattere
Arne GrønlundSammendrag
Ikke tilgjengelig
Forfattere
Arne GrønlundSammendrag
Ikke tilgjengelig
Forfattere
Arne GrønlundSammendrag
Ikke tilgjengelig
Forfattere
Arne GrønlundSammendrag
Ikke tilgjengelig
Forfattere
Arne GrønlundSammendrag
Ikke tilgjengelig
Sammendrag
Rapporten er trykket på russisk
Sammendrag
Leakage of tributyltin (TBT) to coastal environment is documented globally and represents environmental hazards because of long half lives in anaerobic environment and accumulation in biota. Concentrations below 1 ng/l influence marine organisms. Hence, pollution control authorities request abatements to mitigate toxic concentration levels. Dredging of contaminated sediments is one abatement strategy, but this approach requires safe landfill repositories. An alternative strategy is to cover contaminated sea bottom areas by cap layers of favourable composition and thereby reduce TBT exposure to the environment. Both abatement strategies require understanding of chemical and physical processes involved at the pore scale and at the field scale. In the present study pore scale processes are investigated by laboratory experiments on dredged sediments from contaminated sea bottom and integrated to field scale by numerical simulations. The distribution of TBT between solid and water phase is a function of several parameters viz texture; composition of clay minerals; content of organic matter; pH; and salinity in the pore water. The influences of these parameters on the mobility of TBT in sediments are studied with emphasize on variable salinity flux through the porous media. In our data the mobility of TBT increases as a function of decreasing salinity. Long term leakage of TBT is simulated in a typified near shore landfill with initial marine salt water concentration in the pore water. Initial TBT concentration in pore water is estimated to 30 ng/l, which is corresponding to a chemical equilibrium of 1 mg/kg of TBT in the sediments. Because sorption of TBT varies as a function of salinity, the transport of TBT has to be coupled to concentration of NaCl in the pore water. The pore water flow depends not only on the relation between infiltration of meteoric water and permeability of the sediments, but also on the concentration of NaCl, thus Darcy law has to be coupled to transport of NaCl. In this way transport of TBT require a coupling of three types of physics. First is Darcy pore water flow coupled to concentration of NaCl, and then concentration of NaCl is coupled to desorption of TBT.
Forfattere
Nils-Otto KitterødSammendrag
Normal snøsmelting om våren skjer ved delvis smelting om dagen med påfølgende innfrysing om natten. Slike gjentagende smelte- og fryseprosesser kan resultere i mer eller mindre sammenhengende islag under snødekket. Et slikt islag reduserer infiltrasjonskapasiteten i jorda og er årsaken til dannelsen av overflatedammer i forsenkninger i åpent terreng eller på dyrka mark. Når telen går, kan det oppstå situasjoner med svært høye infiltrasjonshastigheter. Dette representerer en forurensningsrisiko dersom vannet i dammene er kontaminert. Med normale infiltrasjonshastigheter vil som regel fysiske, kjemiske og biologiske prosesser i jorda holde forurensningen tilbake og bryte ned mesteparten før det når grunnvannet. Lave temperaturer i infiltrasjonsvannet gjør at nedbrytningsprosesser i jorda går langsommere enn normalt. Kombinert med høye infiltrasjonshastigheter, vil risikoen øke for at grunnvann og nærliggende vassdrag blir forurenset.
Forfattere
M.B. Farmani H. Keers Nils-Otto KitterødSammendrag
Cross-well ground penetrating radar (GPR) data sets were collected in the vadose zone of an ice-contact delta near Oslo"s Gardermoen Airport (Norway) before, during, and after snowmelt in 2005. The observed travel times were inverted using curved-ray travel time tomography. The tomograms are in good agreement with the local geologic structure of the delta. The tomographic results were confirmed independently by surface GPR reflection data and x-ray images of core samples. In addition to structure, the GPR tomograms also show a strong time dependency due to the snowmelt. The time-lapse tomograms were used to estimate volumetric soil water content using Topp"s equation. The volumetric soil water content was also observed independently by using a neutron meter. Comparison of these two methods revealed a strong irregular wetting process during the snowmelt. This was interpreted to be due to soil heterogeneity as well as a heterogeneous infiltration rate. The geologic structure and water content estimates obtained from the GPR tomography can be used in forward and inverse flow modeling. Finally, the water balance in the vadose zone was calculated using snow accumulation data, precipitation data, porosity estimates, and observed changes in the groundwater table. The amount of water stored in the vadose zone obtained from the water balance is consistent with the amount estimated using GPR tomography. Alternatively, the change in water storage in the vadose zone can be estimated using GPR tomography. This may then permit estimates of evapotranspiration to be made, provided other components of the water balance are known.
Forfattere
Anne-Grete Buseth BlankenbergSammendrag
Gis i avrenning er et verktøy som beregner næringsavrenning og erosjon fra landbruksområder. Våtmarker/fangdammer og vegetasjonssoner er eksempler på to tiltak som reduserer N, P og erosjon fra landbruksområder til resipienten.