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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.

2010

Sammendrag

In Nordic countries organic farming started as bio-dynamic farms in the 1930s, and still in the 1970s only a small number of farms were organic. Since then the acreage of organic farming has increased and in 2007 Sweden had 222 268 ha (7.9%), Finland 147 557 ha (6.4 %), Denmark 147 482 ha (5.4%), Norway 43 033 ha (4.7%) and Iceland 4 684 ha (0.27%). In northern areas the short vegetation period combined with low temperatures reducing mineralisation causing nutritional deficit may restrict yields. As mineral fertilizers are prohibited in organic farming, plant nutrition and yield depend on proper microbial activity for nutrient cycling. Plant parasitic nematodes (PPN) reduce plant growth, while microbivorous nematodes (MBN) increase nutrient accessibility. Nitrogen fixating legumes, used to improve soil nitrogen levels, may increase densities of PPN to levels causing crop damage. Management of PPN in organic farming relies on knowledge of population dynamics, damaging thresholds and cultural methods like weed control, sanitation, mulching, crop rotation and resistant cultivars. Keeping PPN below damaging levels and supporting beneficial MBN to improve mineralisation would increase yields and improve quality of organics crops in northern areas. Management of MBN is less well understood, but may be of crucial importance for organic farming in northern areas.

Sammendrag

Currently, very little data exist on the exposure of soil biota to engineered nanoparticles (ENPs), in spite of soils being an important potential sink for ENPs. Though, data on exposure are essential to determine whether or not, or to which extent, a hazard constitutes a risk. This knowledge gap is mainly due to difficulties in tracing ENPs in soils where natural nanoparticles are abundant. We used neutron activated ENPs as tracers and examined the exposure (uptake, excretion and internal distribution) of nanoparticles of cobalt (Co NPs 3.9 ± 0.8 nm) and silver (Ag NPs 20.2 ± 2.5 nm) in the earthworm Eisenia fetida, and compared this to soluble cobalt and silver salts. Accumulation patterns were highly different for cobalt and silver. Concentrations of cobalt in worms after 4 weeks exposure reached 88% and 69% of the Co ions and Co NPs concentrations in food, respectively, while corresponding values for Ag ions and Ag NPs were 2.3% and 0.4%. Both Ag NPs and Ag ions in earthworms were excreted rapidly, while only 32% of the accumulated Co ions and Co NPs were excreted within a 4 months depuration period. High accumulation of cobalt was found in blood, and to a lesser extent in the digestive tract. Sequential extraction and centrifugal ultrafiltration provided useful information on metal speciation, dissolution and bioavailability of Co NPs and Ag NPs. Both Ag NPs and Ag ions were strongly bound to soil constituents, whereas Co NPs and Co ions were largely found as water soluble species, in good agreement with the results from the uptake study.