Distribution and Concentration of Pb and Cd in Two Adjacent Luvisols under Grassland and Forest in Denmark

The effect of land use (forest and grassland) on the deposition and mobility of Pb and Cd has been studied by extraction with 1M HCl, 1M NH₄Ac/HAc and 1M NH₄Ac. The soils were described pedologically and the main physical and chemical parameters were determined. The Pb concentration in the A horizon is higher in the profile under forest than in the profile under grassland. We assign this difference to the filter action of the forest. The Cd concentration is highest in the grassland profile because the forest soil is more degraded and Cd is leached to a higher degree in this soil. Both metals are more mobile (easier to extract) in the forest because the forest soil is most acidic, and because a greater part is bound to organic compounds (humic and fulvic acids) which are more abundant in the forest than in the grassland. The concentrations of Pb and Cd in the A horizons are 26 ppm and 0.1 ppm under the forest and 9 ppm and 0.2 ppm under grassland, respectively.     

Intranasal exposure of the Richardson''s ground squirrel to Western equine encephalomyelitis virus.

Adult Richardson's ground squirrels were infected with western equine encephalomyelitis virus by intranasal instillation. Mortality followed the instillation of a minimum threshold of 4.7 logs of virus while infection was produced by a dosage of 2.3 logs. The incubation period was from four to seven days, being preceded by a viremic phase. Signs were depression, ataxia and paralysis of the limbs. Highest titres of virus were recovered from the brain and histopathological changes involving the central nervous system included meningitis, vasculitis, perivascular cuffing, gliosis, neuronophagia and neuronal degeneration. The virus was also found in a variety of extraneural tissues. Lesions in extraneural tissues included necrosis of brown fat and an apparent increase in number of Kupffer's cells in the liver. The lymphoid tissue was involved indicating a possible source for viremia. The duration and magnitude of viremia were ample enough to provide virus source for arthropods. The potential for transmission of the virus independent of arthropods was discussed in view of the pathogenesis demonstrated in the experimental infections.     

Chemical and sensory quantification of geosmin and 2-methylisoborneol in rainbow trout (Oncorhynchus mykiss) from recirculated aquacultures in relation to concentrations in basin water

Globally, aquaculture systems with water recirculation experience increasing problems with microbial taste and odor compounds (TOCs) such as geosmin and 2-methylisoborneol (MIB). This study investigated the content of geosmin and MIB in water and the flesh of 200 rainbow trouts from eight recirculated aquaculture systems in Denmark. TOC content in the fish flesh was measured by a dynamic headspace extraction method and was evaluated by a sensory panel. The results showed significant correlations between TOC content in water and fish and between chemical analysis and sensory perception. When geosmin exceeded 20 ng/L in the water, 96% of the fish had an intense muddy flavor, but below 10 ng geosmin/L, 18% of the fish (only 3% in special depuration ponds) had an intense muddy flavor. The results indicate that TOC levels <10 ng/L will ensure that a negligible portion of the fish obtains an unpalatable taste and flavor due to TOCs.     

A method for identification and mapping potentially acid sulfate soils in Jutland, Denmark

A method for mapping potentially acid sulfate soils in Jutland, Denmark is described. First the wetlands were outlined, using already existing topographic maps. Then 7900 profiles, evenly distributed over the wetland areas, were examined to point out areas with potentially acid sulfate soils. The method used to identify potentially acid sulfate material was, for carbonate-free samples, a pH-measuring at the sampling time and after the samples were inoculated with soil water extract from an acid sulfate soil and 2, 8 or 16 weeks of incubation. For carbonate-containing samples the pyrite content was compared to the acid-neutralizing capacity. A map was constructed showing the ratio of profiles containing potentially acid sulfate soil samples to total number of profiles examined within natural geographical wetland regions.The investigation showed that 35% of the wetlands in Jutland have a high frequency of potentially acid sulfate soils.     

Production of yarrow (Achillea millefolium L.) in Norway: essential oil content and quality

In 1996, the production of Achillea millefolium L. at different locations in Norway was investigated with regard to the developmental stage. The oil content differed greatly between the vegetative stage (0.13%) and the stage of full bloom (0.34%). Changes in the composition of yarrow essential oil were found to be related to maturation of the plant, with increasing amounts of monoterpenes in relation to the sesquiterpene. However, a clear trend could be detected only for the monoterpenic compounds with increasing levels of alpha- and beta-pinene and alpha-thujone and decreasing levels of sabinene, borneol, and bornyl acetate. Previously reported as major compounds, chamazulene and germacrene D could be found only in insignificant amounts. A solid-phase microextraction (SPME) procedure was applied for screening of the terpenic composition. Sesquiterpenic compounds such as beta-bisabolene, alpha-bisabolol, and delta-cadinene were detected in substantial amounts by SPME in contrast to the steam-distilled samples.     

C and N Turnover and Lignocellulose Degradation During Composting of Miscanthus Straw And Liquid Pig Manure

To obtain a peat substitute for pot plants, Miscanthus straw and liquid pig manure were composted in two different systems (open box and closed reactor) and examined for changes in pH, water content and chemical composition (nitrogen, carbon, hemicellulose, cellulose and lignin). Temperature maxima of 65-70°C were achieved within a few days in both systems. Composting and sampling were continued for 190 days in the box system and 150 days in the reactor. Major loss of nitrogen was found in a period of eight days after temperature maximum followed by stabilization. Accumulation of nitrate was observed during final weeks of composting in both systems. A marked decrease in content of hemicellulose was seen just after temperature maximum followed by slow, constant decrease throughout remaining composting period. The same pattern was observed for degradation of cellulose, though degradation was initiated later in the experiment. Degradation of hemicellulose was nearly 100% in both systems, whereas the cellulose decrease was 64 and 70% in the box and reactor, respectively. Lignin was not degraded during the experiments. Though initial C/N ratio was different in the two systems (25 in box and 16 in reactor), final ratios were the same (C/N=13). In spite of the similarities, the more complicated closed system is preferred if removal of ammonia from exit gas is considered.