Pesticide residues in boreal arable soils: Countrywide study of occurrence and risks.

Large volumes of pesticides are applied every year to support agricultural production. The intensive use of pesticides affects soil quality and health, but soil surveys on pesticide residues are scarce, especially for northern Europe. We investigated the occurrence of 198 pesticide residues, including both banned and currently used substances in 148 field sites in Finland. Results highlight that pesticide residues are common in the agricultural soils of Finland. A least one residue was found in 82% of the soils, and of those 32% contained five or more residues. Maximum total residue concentration among the conventionally farmed soils was 3043 µg/kg, of which AMPA and glyphosate contributed the most. Pesticide residues were also found from organically farmed soils, although at 75-90% lower concentrations than in the conventionally farmed fields. Thus, despite the application rates of pesticides in Finland being generally much lower than in most parts of central and southern Europe, the total residue concentrations in the soils occurred at similar or at higher levels. We also established that AMPA and glyphosate residues in soil are significantly higher in fields with cereal dominated rotations than in grass dominated or cereal-grass rotations. However, risk analyses for individual substances indicated low ecological risk for most of the fields. Furthermore, the total ecological risk associated with the mixtures of residues was mostly low except for 21% of cereal dominated fields with medium risk. The results showed that the presence of mixtures of pesticide residues in soils is a rule rather than an exception also in boreal soils. In highly chemicalized modern agriculture, the follow-up of the residues of currently used pesticides in national and international soil monitoring programs is imperative to maintain soil quality and support sustainable environment policies.

Ultraviolet absorbance of Sphagnum magellanicum, S. fallax and S. fuscum extracts with seasonal and species-specific variation.

Bryophytes, including Sphagnum, are common species in alpine and boreal regions especially on mires, where full sunlight exposes the plants to the damaging effects of UV radiation. Sphagnum species containing UV-protecting compounds might offer a biomass source for nature-based sunscreens to replace the synthetic ones. In this study, potential compounds and those linked in cell wall structures were obtained by using methanol and alkali extractions and the UV absorption of these extracts from three common Sphagnum moss species Sphagnum magellanicum, Sphagnum fuscum and Sphagnum fallax collected in spring and autumn from western Finland are described. Absorption spectrum screening (200-900 nm) and luminescent biosensor (Escherichia coli DPD2794) methodology were used to examine and compare the protection against UV radiation. Additionally, the antioxidant potential was evaluated using hydrogen peroxide scavenging (SCAV), oxygen radical absorbance capacity (ORAC) and ferric reducing absorbance capacity (FRAP). Total phenolic content was also determined using the Folin-Ciocalteu method. The results showed that methanol extractable compounds gave higher UV absorption with the used methods. Sphagnum fallax appeared to give the highest absorption in UV-B and UV-A wavelengths. In all assays except the SCAV test, the methanol extracts of Sphagnum samples collected in autumn indicated the highest antioxidant capacity and polyphenol content. Sphagnum fuscum implied the highest antioxidant capacity and phenolic content. There was low antioxidant and UV absorption provided by the alkali extracts of these three species.

Root discoloration and shoot symptoms in silver birch after Phytophthora infection in vitro.

There are no records of established plant pathogenic Phytophthora species in Finnish forests, but they are likely in the future. Therefore, the effects of Phytophthora inoculations on young, ca. 2-month-old silver birch (Betula pendula) seedling roots and shoots were investigated. Visual inspection of dark discoloration, direct PCR and re-isolation, and detailed root morphology analyses were used to evaluate the effects of Phytophthora inoculation on roots. Symptoms in leaves and stems were also recorded. Phytophthora was successfully re-isolated from 67% of the surface-sterilized roots of inoculated seedlings, but not from the non-inoculated control seedlings. Dark discolorations were found more often in the root segments of inoculated seedlings than in control seedlings. In the Phytophthora-treated seedlings, discoloured root segments were usually linked and found primarily in the main root or lateral roots attached to it, whereas in the control seedlings a few single discoloured root segments were scattered throughout the root systems. The number of root segments was lower in the inoculated than in the control seedlings, indicating root loss after Phytophthora inoculation. In the shoots of inoculated birches, leaf and shoot wilting was observed. The appearance of wilting in shoots without visible dark discoloration in the base of stems indicated that symptoms originated from roots inoculated with Phytophthora.