Reduction of decomposition rates of scots pine needle litter due to heavy-metal pollution

Decomposition of unpolluted Scots pine needle litter was studied in two heavy-metal-pollution gradients in Sweden; one near a brass mill and the other around a primary smelter. In the latter area locally collected polluted Scots pine needle litter was also incubated. Decomposition rates were strongly influenced by the metal pollution and a decrease in the rate of mass-loss occurred. In the brass-mill gradient this occurred until about 1 km from the pollution source which corresponded to about 500 µg Cu and 1 000 µg Zn g^?1 soil. Data are presented to indicate that lignin decomposition was more sensitive to pollution than decomposition of whole litter and affected further away from the pollution sources. At the smelter sites, the metal-polluted needle litter decomposed more slowly than the unpolluted needle litter, and this difference was enhanced close to the smelter. The results indicate that heavy metals accumulated in needles prior to shedding have a long-term impact on the subsequent decomposition of the litter. Both litter quality and soil factors thus contribute to the reduced litter decomposition rate in metal-polluted forests. A new non-linear model with decreasing decay rate was used in the statistical evaluation. The model can be used to characterize the effects of pollution on decomposition rate.     

Optothermistor as a breakthrough in the quantification of lycopene content of thermally processed tomato-based foods: verification versus absorption spectrophotometry and high-performance liquid chromatography

This study reports on the first use of the "optothermistor" as a novel, precise, fast, and low-cost detector of lycopene in a wide range of commercially available processed-tomato products. The quantitative performance of the new device was evaluated by comparing data obtained to that acquired by conventional methods, namely, absorption spectrophotometry and high-performance liquid chromatography (HPLC); the linear correlation was high (R = 0.98). The variation of data obtained with the optothermistor in a series of consecutive measurements performed with the same loading of the sample was better than 1%. However, the repeatability (RSD 0.5-9.0%, n = 3-5) achieved with the optothermistor by independent analyses (multiple loading) is comparable to that of HPLC and spectrophotometry. Results of the studies performed on the 19 products derived from tomatoes demonstrated that the optothermistor is suitable for selective, accurate, precise, and simple determination of lycopene (range = 7-75 mg/100 g of product weight) without the need for a sample pretreatment step. The estimated sensitivity of the present optothermistor is 2 mg of lycopene/100 g of product.     

Relationships between Acid Ions and Carbonaceous Fly-Ash Particles in Deposition at European Mountain Lakes

The concentrations of major ions and spheroidal carbonaceous fly-ash particles (SCPs) in bulk deposition were determined in weekly samples from six European mountain lakes during 1997/98. SCPs are produced only from high temperature combustion of fossil-fuels and therefore provide an unambiguous indicator of atmospheric deposition from this source. Positive correlations were observed between SCPs and SO₄ ^2?, NO₃ ^? and NH₄ ⁺ at all sites except for some determinands at Jorisee (Switzerland) and Starolesnienske (Slovakia). Correlations between SCPs and SO₄ ^2? + NO₃ ^? were always more positive than for SCPs with 'total acid ions' (SO₄ ^2? + NO₃ ^? + NH₄ ⁺). This is in agreement with the expectation that the contribution to NH₄ ⁺ deposition made by fossil-fuels is negligible. Good positive correlations between SCPs and all acid anions were observed at Estany Redo (Pyrenees); lower but still positive correlations were observed for all acid ions with SCPs at Gossenköllesee (Austria), Lochnagar and Kårvatn (central Norway), whilst little trend in correlation was observed for Jorisee and Starolesnienske. It is suggested that this gradient reflects the influence of fossil-fuels on acid deposition in these areas. A high positive correlation was observed between SCP and Cl^? at Gossenkollesee possibly as a result of HCl from coal combustion.     

Testing the Aluminium Toxicity Hypothesis: A Field Manipulation Experiment in Mature Spruce Forest in Norway

Aluminium (Al) has been considered to be a central element for risk evaluation of forest damage due to acidification. It has been hypothesized that Al reduces root growth, nutrient uptake and forest vitality. However, forest monitoring studies fail to show correlations between soil acidification and forest health. In general, no direct relation between Al concentration and forest health has been established. Here, Al concentrations in soil solution were manipulated by weekly additions of dilute AlCl₃ to levels that are believed to be unfavorable for plant growth. Four treatments (in triplicate), including a reference and three Al addition levels, were established. Effects of enhanced Al concentrations on fine root growth, nutrient uptake and crown condition in a mature Norway spruce forest in Norway were tested (1996–1999). After three years of manipulation, crown condition, tree growth and fine root growth were not affected by potentially toxic Al concentrations. However, the Mg content in current year's needles decreased at the highest Al addition treatment. The Mg/Al ratio of fine roots of the same treatment had declined too, which suggests that Al blocked Mg uptake at the root surface. The manipulation will be continued for two more years.     

Modelling ”clean rain” treatments in acidified soils-EXMAN project results

The SAFE dynamic model was applied to a ”clean rain” roof experiment performed within the EXMAN project. In the experiment ambient throughfall was removed and replaced with artificial ”clean throughfall”. Input of S, N and H to the forest ecosystem was reduced by 75–100%. The results of the modelling show, that the time scales of model predictions and experiments are the same. The change in base cation flux was well reproduced, while the simulation of changes in aluminum flux was less successful. pH stayed constant in the experiment as well as in the calculations.     

EFFECT OF REGION OF INTEREST SELECTION AND UPTAKE MEASUREMENT ON GLOMERULAR FILTRATION RATE MEASURED BY 99mTc-DTPA SCINTIGRAPHY IN DOGS

Determinations of different methods of measurement of uptake of 99mTc-DTPA using scintigraphy of glomerular filtration rate (GFR) were made from 29 studies on 10 healthy beagle dogs. GFR was measured by calculating the percentage dose uptake (integral method) and rate of uptake (slope method) of 99mTc-DTPA using manual kidney regions of interest (ROI) and automatic kidney and background ROIs at different time periods of the uptake phase. These results were compared using linear regression analysis to the GFR obtained from 99mTc-DTPA plasma clearance using multiple blood samples. The best correlation coefficient between percentage DTPA uptake and GFR by DTPA clearance (r = 0.84, P < 0.001) was derived from time intervals between 30s-120s with a perirenal background ROI at 1 or 2 pixels out from the kidney ROI using automatic kidney ROI at 20% threshold. With the slope method, the best correlation coefficient (r = 0.85, P < 0.001) was obtained from time intervals between 30s-peak with the background ROI at 2 pixels out from the kidney ROI using automatic ROI at 35% threshold. The offset was higher, and the correlation varied more with different ROIs and the method was unreliable at time intervals extending beyond the peak radioactivity. Manual kidney ROIs with automatic background ROIs had slightly lower correlations. With DTPA renography both integral and slope uptake method with automatic kidney and background ROIs are accurate methods to estimate the GFR, but that the integral method is much more stable to variations in ROI size and the duration of the uptake phase of the renogram.     

Einsatz bakterieller Antagonisten zur Bekämpfung von Krankheiten verursacht durch Rhizoctonia solani

Rhizoctonia solani is an important soil-borne pathogen causing diseases in numerous economically important crops. The pathogen R. solani can be responsible for relevant yield losses as well as on lettuce and potato. To develop a biocontrol strategy, two bacterial strains, Pseudomonas fluorescens L13–6-12 and Serratia plymuthica 3Re4–18 were evaluated against R. solani causing black scurf in potato and bottom rot in lettuce. The disease suppression effect of the two antagonists was tested as well as in a climate chamber and in the field during two vegetation periods. The results of the climate chamber experiments showed, that R. solani can significantly reduced the lettuce growth. The dry mass losses on lettuce and the disease severity on potato sprouts were significantly limited through bacterization. The antagonist L13–6-12 showed best disease suppression effect in climate chamber experiments on both crops. A significant lower disease severity was to observed in treatments with bacterial antagonists as well as on lettuce plants and harvested potato tubers during both vegetation periods. Also the dry mass losses on lettuce were clear reduced in treatments with bacterial antagonists, whereas only a partly limitation of yield losses on potato was to achieved. In summary, the results supported that the use of bacterial antagonists can be part of a control strategy against R. solani.     

Sandwich enzyme-linked immunosorbent assay (ELISA) for measuring the concentration of, and detection of antibodies to, Aujeszky's disease virus

A double antibody sandwich enzyme-linked immunosorbent assay (ELISA) was developed for measuring Aujeszky's disease virus (ADV) antigen concentration and an inhibition technique based on the former was developed for detection of antibodies to ADV. The results were checked by determining the cytopathic and serum neutralization titres. The correlation was satisfactory in both cases, with correlation coefficients above 0.8. When measuring ADV antigen concentration, the lower limit of detection was 10(3) TCID 50/0.2 ml. The sensitivity of ELISA in detecting antibodies to ADV was found to be superior to that of the serum neutralization test and, thus, enabled the testing of rabbit and guinea-pig sera.     

Fusobacterium necrophorum and Bacteroides melaninogenicus as etiologic agents of foot rot in cattle.

Fusobacterium necrophorum (Sphaerophorus necrophorus) and Bacteroides melaninogenicus were the predominant bacteria isolated from biopsy specimens of lesions in cattle affected with foot rot. Mixed inoculums of the 2 bacteria, applied to the scarified interdigital skin or inoculated intradermally into the interdigital skin of test cattle, induced typical lesions of foot rot. Both bacteria were reisolated in large numbers from the induced lesions.