Ion Leaching Before and After Clear-Cutting in a Norway Spruce Stand - Effects of Long-Term Application of Ammonium Nitrate and Superphosphate

Soil solution chemistry was measured in a Haplic Podzol in a Norway spruce (Picea abies, L.Karst) site in central Sweden that had received frequent low-dose applications of nitrogen (N) asammonium nitrate (30-120 kg N/ha yr) and phosphorus (P) as superphosphate (20-40 kg P/haabout every third year) over a long period (22 yr). The aim was to investigate effects of added Non the ion leaching before and after clear-cutting. The N load corresponded well with actual loadsin central Europe. Prior to clear-cutting, fertilization increased concentrations of several ions inthe soil solution. Total losses of NO ₃ ^- , Al andH⁺ increased with the intensity of fertilization. However, since fertilization enhanced tree growthand nutrient uptake, differences between the total losses of several other ions tended to beequalized. After clear-cutting, the pH in the soil solution decreased, and the losses of Mn and Alincreased with fertilizer load, probably because of increased N mineralization and nitrification. Inthe N treatments the concentration of SO ₄ ^2- in the soil solution decreased, probably owing toincreased adsorption in the B horizon in response to the pH decrease. The effects ofanthropogenic N deposition are discussed in the light of our findings and possible causes oftemporal and spatial variation in soil solution chemistry and ion fluxes are suggested.     

Fluxes of CO2, CH4 and N2O from drained organic soils in deciduous forests

We examined net greenhouse gas exchange at the soil surface in deciduous forests on soils with high organic contents. Fluxes of CO₂, CH₄ and N₂O were measured using dark static chambers for two consecutive years in three different forest types; (i) a drained and medium productivity site dominated by birch, (ii) a drained and highly productive site dominated by alder and (iii) an undrained and highly productive site dominated by alder. Although the drained sites had shallow mean groundwater tables (15 and 18 cm, respectively) their average annual rates of forest floor CO₂ release were almost twice as high compared to the undrained site (1.9±0.4 and 1.7±0.3, compared to 1.0±0.2 kg CO₂ m⁻² yr⁻¹). The average annual CH₄ emission was almost 10 times larger at the undrained site (7.6±3.1 compared to 0.9±0.5 g CH₄ m⁻² yr⁻¹ for the two drained sites). The average annual N₂O emissions at the undrained site (0.1±0.05 g N₂O m⁻² yr⁻¹) were lower than at the drained sites, and the emissions were almost five times higher at the drained alder site than at the drained birch site (0.9±0.35 compared to 0.2±0.11 g N₂O m⁻² yr⁻¹). The temporal variation in forest floor CO₂ release could be explained to a large extent by differences in groundwater table and air temperature, but little of the variation in the CH₄ and N₂O fluxes could be explained by these variables. The measured soil variables were only significant to explain for the within-site spatial variation in CH₄ and N₂O fluxes at the undrained swamp, and dark forest floor CO₂ release was not explained by these variables at any site. The between-site spatial variation was attributed to variations in drainage, groundwater level position, productivity and tree species for all three gases. The results indicate that N₂O emissions are of greater importance for the net greenhouse gas exchange at deciduous drained forest sites than at coniferous drained forest sites.     

High-resolution NMR and diffusion-ordered spectroscopy of port wine

The use of high-resolution NMR and high-resolution diffusion-ordered spectroscopy (DOSY) for the characterization of selected Port wine samples of different ages with the aim of identifying changes in composition is described. Conventional 1D and 2D NMR methods enabled the identification of about 35 compounds, including minor components such as some medium-chain alcohols, amino acids, and organic acids. High-resolution (HR) DOSY extended sample characterization, increasing the number of compounds identified and NMR assignments made, by providing information on the relative molecular sizes of the metabolites present. Port wines of different ages were found to differ mainly in their content of (a) organic acids and some amino acids, (b) an unidentified possible disaccharide, and (c) large aromatic species. The relative amount of these last high Mw aromatics is seen to decrease significantly in the oldest wine, as expected from the known formation and precipitation of anthocyanin-based polymers during red wine aging.     

Inhibition of cancer cell proliferation in vitro by fruit and berry extracts and correlations with antioxidant levels

The effects of 10 different extracts of fruits and berries on cell proliferation of colon cancer cells HT29 and breast cancer cells MCF-7 were investigated. The fruits and berries used were rosehips, blueberries, black currant, black chokeberries, apple, sea buckthorn, plum, lingonberries, cherries, and raspberries. The extracts decreased the proliferation of both colon cancer cells HT29 and breast cancer cells MCF-7, and the effect was concentration dependent. The inhibition effect for the highest concentration of the extracts varied 2-3-fold among the species, and it was in the ranges of 46-74% (average = 62%) for the HT29 cells and 24-68% (average = 52%) for the MCF-7 cells. There were great differences in the content of the analyzed antioxidants in the extracts. The level of the vitamin C content varied almost 100-fold, and the content of total carotenoids varied almost 150-fold among the species. Also in the composition and content of flavonols, hydroxycinnamic acids, anthocyanins, and phenolics were found great differences among the 10 species. The inhibition of cancer cell proliferation seen in these experiments correlated with levels of some carotenoids and with vitamin C levels, present at levels that can be found in human tissues. The same inhibition of cell proliferation could not be found by ascorbate standard alone. This correlation might indicate a synergistic effect of vitamin C and other substances. In MCF-7 cells, the anthocyanins may contribute to the inhibition of proliferation.     

Mercury in the Swedish mor layer — linkages to mercury deposition and sources of emission

The report deals with data from 363 Swedish mor samples. The following parameters are discussed: Hg-, organic and Se-concentrations and Hg-quantity in mor, Hg- and S-deposition from Swedish and continental emissions (point sources and diffuse emissions) and precipitation. The results are focused on mean, geographical variations, statistical correlations and calculations to get first insights and order of magnitude data on the linkages between the Hg-contamination of the Swedish mor layer and the various sources of Hg-emissions. Southern Sweden is significantly influenced by continental Hg-emissions. Several previously unknown domestic discharge sources of Hg have been identified. The total amount of Hg in the Swedish mor layer has been estimated to be about 615 t. East. Germany, United Kingdom, West Germany and Poland seem to have contributed with the largest continental emissions of Hg entering the Swedish mor layers. The countries which early started to build up their industry probably are responsible for greater Hg-contamination than indicated by our figures, and vice versa. If no measures are taken to reduce the emissions, the present contamination will continue. Then, the ‘burden of guilt’ ought to be redistributed so that a higher proportion of the Swedish Hg-contamination would be linked to continental discharges since considerable reductions have already occurred as regards Hg-discharges from large Swedish sources. The problems with elevated Hg-levels in the mor layer and, at the end point, the high concentrations of Hg in lake fish in Sweden, will remain far into the next century.     

Critical loads for nitrogen deposition on forest ecosystems

Critical loads for N deposition are derived from an ecosystem's anion and cation balance assuming that the processes determining ecosystem stability are soil acidification and nitrate leaching. Depending on the deposition of S, the parent soil material, and the site quality critical N deposition rates will range between 20 to 200 mmol m^?2 yr^?1 (3 to 14 kg ha^?1 yr^?1) on silicate soils and reach 20 to 390 mmol m^?2 yr^?1 (3 to 48 kg ha^?1) on calcareous soils.     

Possibilities for Increased Carbon Sequestration through the Implementation of Rational Forest Management in Russia

Huge areas of the Russian forests suffer from insufficient forest management. A scenario has been developed for an improved management program that would be implemented over the next 40 years. Possible options have been aggregated into three interlinked groups: increase in forest productivity through improvement of the forest conditions and the structure of the Forest Fund, decrease of carbon release by mitigation of disturbance regimes, and improvement of landscape management. One prerequisite in developing this scenario was that the cost of sequestering one ton of carbon should not exceed US$3 (1992 dollar value). In this article a simple model is described to illustrate the following possibilities for increased carbon fixation by improved forest management: large-scale reforestation and afforestation, replacement of stands with low productivity and replacement of so called soft deciduous species and “climax” stands, and implementation of rational silviculture (thinning). The results indicate a potential for an increase in carbon fixation in Russian forest ecosystems of 24.4 Pg over 100 years, after the first year that the actions discussed are implemented. The net sink of carbon was determined to be 16.5 Pg in the “low” estimate and 42.5 Pg in the “high” estimate. There are, however, many uncertainties in the data and there are difficulties in adequately modeling the possibilities for implementation under current conditions in Russia. In spite of these uncertainties, we conclude that there is great potential for economically justified increased carbon fixation through improved forest management in Russia.     

Effects on soils and leaching after application of dolomite to an acidified forested catchment in the Lake Gårdsjön watershed,south-west Sweden

The dry forest soils (80%) of a 3.3 ha catchment in Gårdsjön, were treated with 1.5 ton/ha dolomite in 1984. In half the catchment an additional dose of 4.5 ton/ha was added in 1986 (i.e. totaly 6 ton/ha). By 1991 the concentrations of exchangeable calcium and magnesium had increased by 450% to 800% in the humus layer and upper 0–5 cm of the mineral soils and by 500% and 300%, respectively, in the 5–10 cm and 10–20 cm soil depth in the 6 ton/ha part. By 1.5 ton, Ca and Mg increased in humus and 0–5 cm in the mineral soil. Potassium decreased in the humus and the mineral soil with both 1.5 ton and 6 ton per ha. The accumulated output of K by runoff was however only 1 kg during the 6 years until 1992, which indicates that the losses from the soil also may have resulted in increased uptake by the forest. Tree growth and nutrient content in current needles was, however, unchanged. Increased contents of Mg, Ca and Zn was observed in some species of ground vegetation. Nitrate and ammonium concentrations and fluxes in runoff were identical to the reference catchment, while inorganic Al and Mn decreased by 40–50% and H⁺ by 30%. The accumulated extra output by runoff of Mg was about 7% and of Ca 0.6% of the amounts applied by the two treatments in 1984 and 1986.     

Antioxidants, low molecular weight carbohydrates, and total antioxidant capacity in strawberries (Fragaria x ananassa): effects of cultivar, ripening, and storage

Four cultivars of strawberries (Senga Sengana, BFr77111, Elsanta, and Honeoye) were studied for their content of antioxidants, total antioxidant capacity, and low molecular weight carbohydrates in relation to harvest year, ripening stage, and cold storage. For ascorbic acid, chlorogenic acid, ellagic acid, and total antioxidative capacity, measured in both water-soluble and water-insoluble extracts, there was a 2-5-fold variation among cultivars. Unripe berries contained lower concentrations of chlorogenic acid and p-coumaric acid and also quercetin and kaempferol compared with riper berries. During cold storage for up to 3 days, relatively few changes in the concentration of the different antioxidants occurred. The concentrations of several investigated parameters were interrelated, for example, for ascorbic acid and water-soluble antioxidant capacity and for ellagic acid and water-insoluble antioxidant capacity. The dominating sugars in strawberries were fructose and glucose, but considerable amounts of sucrose were also present, and their contents varied among cultivars, giving a predicted glycemic index of approximately 81. Verbascose, raffinose, and stachyose were found in only minor amounts. The study shows that the concentration of a number of bioactive compounds in strawberries varied according to cultivar, ripening stage, and storage. This information should make it possible to select strawberries with an optimal content of bioactive compounds.