Characterization of nematode colonization and succession in disturbed soil using the Maturity Index

Nematode colonization and succession were studied over 60 weeks in field plots which had been disturbed by combinations of fumigation and manuring. It was expected that the Maturity Index, which is based on the composition of the nematode fauna, would decrease after disturbance, and subsequently increase with recovery and succession. The results showed that in all treatments, the initial colonization and growth were due to taxa scaled in colonizer-persister (c-p) group 1, resulting in a low Maturity Index. An increase in this index followed when these taxa were gradually replaced by c-p group 2 which thereafter remained the dominant group. C-p groups 3–5 developed only in the non-fumigated treatment. Manuring caused characteristic changes in the nematode fauna which could be described as a cycle, starting with an increase in enrichment opportunists (c-p 1), which were succeeded by general opportunists (c-p 2) which, in turn, were supplemented with persisters (c-p 3–5). It is expected that the same cycle will be observed as a result of other disturbances that cause temporary increase in food supply.     

Hierarchical tree classifiers to find suitable sites for sandplain grasslands and heathlands on Martha’s Vineyard Island, Massachusetts

The grasslands and heathlands of Martha’s Vineyard Island, Massachusetts provide habitat for unusual, rare, and endangered species. Currently, these globally rare ecosystems exist as fragments on the southern coast of the island within a matrix of wooded, agricultural, and developed land. We used existing land cover patterns to train a hierarchical tree classifier model according to 10 biogeoclimatic and positional variables. This model was then used to predict suitable sites where grasslands and heathlands do not presently occur but could be efficiently established. The tree classifier model indicates that many sites compatible with sandplain grasslands currently contain agricultural lands, residential development, mowed grassland, and commercial development. Efficient establishment could be undertaken at locations buffering existing grasslands to increase their extent by 67% relative to current conditions and join isolated fragments. Sites compatible with heathlands also currently contain agriculture and residential development as well as later successional vegetation including maritime forests and pitch pine. Conversion of these sites to heathlands, as indicated by the model, would increase the current extent by 25% and increase average patch size. An adaptive management approach to grassland and heathland supplementation could be employed to validate the causal mechanisms between the predictor variables and the vegetative communities. Testing of the predictive accuracy of the Martha’s Vineyard Island tree classifier models at other coastal sites would also provide information on the true mechanisms responsible for distribution patterns.     

Input of Atmospheric Particles into Forest Stands by Dry Deposition

In this study the dry input of atmospheric particles into a forest stand is quantified. A wash-off-method using the natural leaf surfaces as collectors of the dry deposition was chosen. The direct on-site-measurement on living branches were achieved in a spruce stand (Picea abies (L.) Karst) at Solling, Germany. The ion exchange processes occurring on natural branches can reliably be quantified through immediate sequential washings. In order to calculate also the gas dry deposition of those trace elements which occur in both particle and gas phases, a resistance model was used. From these results the deposition velocity of particulate aerosol components into the forest stand was calculated. Dry particle deposition constitutes an important part of the total matter input into the forest ecosystem. Just the nitrogen input into Solling only by dry deposition (from particle-, mist-, and gas-deposition) with about 30 kg N ha^?1 a^?1 already exceeds the critical load of 20 kg N ha^?1 a^?1 by far, and this is without even considering the additional load by wet deposition which amounts to 15 kg ha^?1 a^?1. These findings are of greatest ecological importance, as the damage to the stability of the forest ecosystem caused by increased nitrogen input is considerable. Only a quick and drastic reduction of sulphur and nitrogen emissions could stop the further increase of the nutritient imbalance and the progressing acidification of this ecosystem.     

Free radical generation assays: new methodology for accelerated oxidation studies at low temperature in complex food matrices

A novel method for the rapid screening of antioxidant efficacy and oxidative stability in food and feed matrices has been developed. The analyses are described as free radical generation (FRG) assays. The new procedure combines the use of azo-initiators with analytical equipment that is widely used for antioxidant research such as the oxidative stability instrument and the oxygen bomb. The use of initiators instead of high temperatures as a driving force to increase the rate of oxidation improves the correlation between the accelerated screening of foodstuffs and real shelf life. The improved correlation can be mainly explained by the fact that food products are analyzed in their original status, maintaining all interfacial phenomena of the food matrix. Furthermore, the lower temperature of analysis reduces differences between the reaction kinetics of the assay and those of the oxidation during actual shelf life. Consequently, the correlation between the accelerated analysis and shelf life is improved, particularly when compared to accelerated oxidation at high temperatures. The FRG assays could be used successfully to evaluate the efficacy of natural antioxidants in heat-sensitive food products such as emulsions and meat products. A good correlation was observed between the accelerated tests and the oxidation parameters obtained from standard shelf-life evaluation. It was possible to successfully compare the efficacy of several antioxidants and to predict shelf life for these heat-sensitive food matrices.     

Lead dietary intake in a Spanish population (Canary Islands)

For most people diet is the main route of exposure to trace metals, so information about dietary intake is also important to assess risks to human health for these elements. The purpose of this study was to determine the levels of Pb in the foods and drinks of highest consumption in the authors' our community to estimate daily intakes of Pb for each of the seven Canary Islands. Four hundred and twenty samples were analyzed using GFAAS. The total Pb intake of the Canarian population is 72.8 microg/day, 29.12% (for a person of 70 kg body weight) of the provisional tolerable weekly intake limit of 25 microg/kg fixed by the FAO/WHO. The island that presents the highest lead intake is La Gomera, followed by Lanzarote, Tenerife, and Gran Canaria islands. These four islands present a lead dietary intake over the mean Pb intake for the whole archipelago. The islands with lower Pb intakes are La Palma and Fuerteventura, with intakes under 70 microg/day. These results have also been compared with the values found for other national and international communities.     

Effects of treatment and flow on the deoxygenation rate constant

The laboratory bench-scale experiments were conducted to investigate the effects of varying degrees of waste treatment and the flow conditions in the receiving waters on the deoxygenation rate constant (k), and ultimate biochemical oxygen demand (L), and the total O₂ utilisation of the receiving waters. Industrial wastewaters were collected from 10 major industrial plants located along the Houston Ship Channel in Texas. Two different degrees of treatment for industrial wastewaters were studied. Three different flow conditions studied were the high, the average and the low flow in the Houston Ship Channel. The k values increased for both further treatment and decreased flow in the reactor runs. The L values were higher for the average flow conditions than for the low flow conditions. The total O₂ utilization was found to increase with a decrease in the flow of the receiving waters.     

Identification of urolithin a as a metabolite produced by human colon microflora from ellagic acid and related compounds

Dietary ellagic acid and related polyphenols are metabolized in humans to dibenzopyran-6-one derivatives, and the microbial origin of these metabolites has been suggested. However, this has not been demonstrated so far. Fecal samples donated by six volunteers were incubated under anaerobic conditions, and aliquots were used to evaluate the fecal metabolism of ellagic acid, the ellagitannin punicalagin, and an ellagitannin rich extract from walnuts. The isoflavone daidzein was also incubated with the same fecal samples to follow the production of the microbial metabolites previously reported (dihydrogenistein, O-demethylangolensin, and equol) as a positive control of the system and to evaluate similarities between isoflavone and ellagic acid fecal flora metabolism. After fermentation the metabolite "urolithin A" (3,8-dihydroxy-6H-dibenzo[b,d]pyran-6-one) was produced from ellagic acid, punicalagin, and the ellagitannin extract in all the fecal cultures from different volunteers, but with very different production rates and concentrations. This large variability in the concentration of metabolite and kinetics of metabolite production is consistent with the large variability found in the excretion of these metabolites in urine in vivo after human consumption of ellagitannins, and with differences in the composition of the fecal microflora. No correlation between isoflavone and ellagic acid metabolism by fecal microflora was observed. The present study confirms the microbial origin of the recently reported in vivo generated hydroxy-6H-dibenzo[b,d]pyran-6-one derivatives in humans and is a further step in the study of the bioavailability and metabolism of ellagic acid and ellagitannins.     

Countercurrent supercritical fluid extraction and fractionation of high-added-value compounds from a hexane extract of olive leaves

Countercurrent supercritical fluid extraction (CC-SFE) at a pilot scale plant was used for fractionation of high-added-value products from a raw extract of olive leaves in hexane. Compounds found in the raw extract were waxes, hydrocarbons, squalene, beta-carotene, triglycerides, alpha-tocopherol, beta-sitosterol, and alcohols. The CC-SFE extraction process was investigated according to a 2(3) full factorial experimental design using the following variables and ranges: extraction pressure, 75-200 bar; extraction temperature, 35-50 degrees C; and ethanol as modifier, 0-10%. Data were analyzed in terms of extraction yield, enrichment, recovery, and selectivity. Higher extraction yields were attained at 200 bar. For most of the compounds analyzed enrichment was attained at the same conditions, that is, 75 bar, 35 degrees C, and 10% ethanol. Hydrocarbons were usually recovered in the separators, whereas waxes and alpha-tocopherol remain in the raffinate. Selectivity data reveal that alpha-tocopherol is the most easily separable compound. The influence of the experimental factors on the recovery of all the compounds was studied by means of regression models. The best fitted model was attained for beta-sitosterol, with R2 = 99.25%.     

Determination of Plant-Available Nutrients in Two Wood Ashes: The Influence of Combustion Conditions

Wood ashes were traditionally used as a fertilizing agent from the very beginning of working land but the fertilizing quality varies according to the combusted biomass and also the industrial burning equipment. The differences between wood ash originated from fluid and classic boiler were investigated by X-ray powder diffraction (XRD), X-ray fluorescence spectrometry (XRF), differential thermal analysis (DTA), thermo-gravimetric analysis (TGA), scanning electron microscopy (SEM), and Mehlich 3 and deionized water extraction procedures in relation to extraction time. The results, especially of the SEM and chemical extractions, have demonstrated that the type of burning boiler determines the portions of the leachable nutrient elements. The silica and alumina ash content conducted by the elevated temperature transforms the main proportion of calcium and potassium into the insoluble feldspars. Due to this effect only a small amount of nutrients could be released and served as a fertilizing matter.     

Decrease in Acid Deposition - Recovery in Norwegian Waters

Concentrations of sulphate in precipitation in southern Norway have decreased by 50–60% from 1980–1999. This has caused a decrease in sulphate concentrations in lakes of 30–40% from 1986–1999. Nitrogen in precipitation has decreased slightly over the last 10-years. In lakewater there has also been a significant but slight decrease. Concentrations of non-marine base cations in precipitation have decreased by 40% from 1980–1999. In lakewater, non-marine base cation concentrations have been at about the same level the last 10 years. This indicates that acid deposition has decreased sufficiently such that the pool of exchangeable base cations in the soil is now being replenished. The acidification situation in lakes in Norway has thus shown a clear improvement over the last 8–10 years. pH, alkalinity and ANC (acid neutralising capacity) have all increased. Concentrations of inorganic (toxic) aluminium species have decreased. The trends in H⁺ and Alⁿ⁺ do not follow the relation expected if Alⁿ⁺ concentrations were governed solely by a single solid phase of Al(OH)₃.