Inhibitory effect of low partial pressures of acetylene on nitrification

The inhibiting effect of C₂H₂ on nitrification was investigated in two agricultural soils. Nitrification was totally inhibited at 10 Pa partial pressure of C₂H₂ which is lower than previously reported for soils. There were no differences in rates of nitrate production between flasks without C₂H₂ and flasks with C₂H₂ at 0.01 Pa, while there was an effect on nitrification at 0.1 PaC₂H₂. At 0.1 Pa no inhibition was noted during the first 3 days; after this period nitrification was partially inhibited. The inhibiting effect did not cease until 7 days after removal of C₂H₂. The sensitivity of nitrification to low concentrations of C₂H₂ should be noted when denitrification rates are determined by the use of the acetylene inhibition method (usually C₂H₂ at 10kPa).     

Technological solutions and operational measures to prevent escapes of Atlantic cod (Gadus morhua) from sea cages

Escapes of cod (Gadus morhua) from sea cages represent an economic problem for farmers and a potential environmental problem. We estimate that 0–6% of cod held in sea‐cage farms in Norway were reported to have escaped each year from 2000 to 2005, which is a high proportion compared with salmon. We interviewed employees at 19 coastal sea‐cage cod farms in Norway to investigate both how and why cultured cod escape and to document cage handling and management strategies that were effective in minimizing escapes. Based on the interviews, we describe five working hypotheses that may explain why a greater proportion of cod than salmon escape: (1) cod are more willing to escape than salmon; (2) cod bite the net cage and create wear and tear; (3) net cages have insufficient technical standards for cod culture; (4) cod are placed in sea cages at considerably smaller sizes than salmon; and (5) cod are more popular feed for predators. Preliminary testing of the hypothesis that cod bite netting and create holes was done by placing pre‐damaged net panels with cut twines and control panels inside sea cages. Holes in the pre‐damaged net panels increased in size over a period of 3 months. The type of damage indicated that biting of netting twines was the likely cause.     

Retention of aspen (Populus tremulae) at final cuttings - The effect of dead wood characteristics on saproxylic beetles

To preserve biodiversity in managed forest landscapes dead and living trees are retained at final cuttings. In the present study we evaluated the effect of these practices for saproxylic (wood-dependent) beetles inhabiting dead aspen trees (Populus tremulae). For saproxylic beetles, tree retention at final cuttings can be expected to be especially valuable for species adapted to sun-exposed dead wood, a substrate that only rarely occurs in well managed forest stands. Therefore, the current evaluation was conducted as a comparison of species richness, species density (number of species per sample), assemblage composition and occurrence of individual species between clear-cuts, where aspen trees were retained, and closed forest stands with aspen trees. The study was conducted in central Sweden and the beetles were sampled by sieving of bark from CWD (coarse woody debris) of aspen. There was no significant difference in rarefied species richness between forest and clear-cut sites. Species composition differed significantly between the two stand types. Generalized linear mixed-effects models predicted the species density to be 34% lower in CWD objects in forest sites than on clear-cuts. This pattern could partly be explained by differences in CWD diameter, decay class and bark types between the two stand types (clear-cut/forest). Stand type was a significant predictor of occurrence in individual CWD objects for 30% of analysed individual beetle species. For all species except one, the variable stand type predicted higher occurrence on clear-cuts than in forest stands. To conclude, our results demonstrate that retention of aspen on clear-cuts contributes to population recruitment of a different assemblage of species than CWD within stands.     

Changes in soil ph over a 50-year period under different forest canopies in SW Sweden

Reinvestigation of soil profiles, down to 70 cm depth in mineral soil, sampled for measurements in 1927 revealed a general decrease in pH for spruce and hardwood stands with 0.3 to 0.9 units. The pH-changes in the top soil can partly be explained by biological acidification, increasing with stand age. Stand age and species composition have less influence in deeper soil horizons and much of the acidification there is ascribed to acid deposition.     

Antioxidant properties of carnosine re-evaluated in a ferrylmyoglobin model system and in cooked pork patties

The antioxidative effect of purified carnosine (i.e., separated from the common contaminant hydrazine) has been evaluated in two systems: (i) Carnosine was found to possess poor reducing properties toward the prooxidant ferrylmyoglobin; at pH approximately 5 the presence of carnosine did not increase the rate of reduction of MbFe(IV)=O compared to autoreduction, whereas at pH 7.4 the rate constant for reduction by carnosine was 0.010 +/- 0.002 M(-1).s(-1) (I = 0.16; 25.0 degrees C). (ii) In cooked pork patties prepared from meat (longissimus dorsi and masseter) with purified or nonpurified carnosine added, the effect of purified carnosine was insignificant when compared to control patties, whereas patties with carnosine contaminated with hydrazine had a lower oxidation level than patties with purified carnosine. Carnosine is concluded not to deactivate the prooxidant ferrylmyoglobin and not to have any antioxidative effect in cooked pork.     

Antioxidant properties of green tea extract protect reduced fat soft cheese against oxidation induced by light exposure

The effect of two different antioxidants, EDTA and green tea extract (GTE), used individually or in combination, on the light-induced oxidation of reduced fat soft cheeses (0.2 and 6% fat) was investigated. In samples with 0.2% fat, lipid hydroperoxides as primary lipid oxidation products were not detected, but their interference was suggested from the formation of secondary lipid oxidation products such as hexanal and heptanal. The occurrence of these oxidation markers was inhibited by spiking with 50 ppm EDTA or 750 ppm GTE, or a combination of the two prior to irradiation. In contrast, addition of 50 ppm EDTA to samples with 6% fat was ineffective, but 750 ppm GTE (alone or in combination with EDTA) strongly reduced levels of hexanal and heptanal. Accumulation of primary lipid hydroperoxides was not affected by GTE, hence antioxidative activity was ascribed to scavenging of hexanal and heptanal precursors. These radical intermediates result from hydroperoxide disintegration, and subsequent scavenging by GTE, which acts as a radical sink, corroborates the intense signal observed by electron paramagnetic resonance (EPR) spectroscopy.     

Plant-derived CO2 flux from cultivated peat soils

Abstract

Methods used to estimate the CO₂ emission from soil commonly measure the total CO₂ flux. To be able to quantify the net CO₂ emission from cultivated peat soils there is a need to distinguish between soil organic matter-derived CO₂ respiration and plant-derived respiration. In this investigation we used the root exclusion method to separate the plant-derived respiration from total CO₂ emission. The plant-derived contribution was estimated to be between 27 and 63% of total CO₂ emission depending on soil type and season. We also found a relationship between soil temperature, biomass growth and CO₂ efflux, which can be used to estimate plant-derived respiration. Due to the priming effect the root exclusion method is less reliable late in the season.     

Effects of Family Housing on Behaviour,Plasma Cortisol and Performance in Adult Female Mink (Mustela vison)

Various behavioural, physiological and production-related parameters were examined in 200 adult female pastel and pearl mink either family housed in three-room cages with no weaning or housed singly in one-room cages after normal weaning procedures. Scanning observations of behaviour and use of the cages were performed in the nursing period and several parameters related to reproduction were registered. The adult female mink were weighed when kits were 16 weeks old (September) and again at pelting time (November). Blood samples were collected from all adult female mink in September at which time the teat condition and fur damage were evaluated. After pelting, bite marks on the leather side of the skin were counted, fur damage was graded after severity and the fur size was measured. Some positive consequences of being family housed were revealed. The familyhoused adult female mink showed a lower level of stereotypes and a higher level of defensiveness and curiosity than the adult female mink in one-room cages during the nursing period. In September and November, family-housed adult females were heavier than singly housed adult females. However, most of the physiological or production-related parameters pointed in a negative direction for familyhoused adult female mink. Reproductive success was somewhat reduced, although not significantly. Plasma cortisol levels were elevated in September, indicating higher levels of stress in these females. They showed a generally poor teat condition in September, with a high proportion of swollen or bitten teats. A high proportion of these adult females showed fur damage in both September and November, and a high number of bite marks was found on the leather side of the skins of these females, indicating that family housing had a high cost for the adult female mink. In conclusion, there seem to be some benefits, at least on the behavioural level, in keeping adult female mink in three-room cages during the nursing period, but both physiological and production-related parameters indicated that the welfare of the adult female mink was threatened if she was continuously cohoused with her litter past the normal age of weaning.     

A New Shift‐Share Method

Shift‐share analysis is a decomposition technique widely used in regional studies to quantify an industry‐mix effect and a competitive effect on the growth of regional employment (or any other relevant variable) relative to the national average. This technique has always been subject to criticism for its lack of theoretical basis. This paper presents a critical assessment of the methods suggested by Dunn and Esteban‐Marquillas and proposes a new shift‐share method, which separates out the two effects unambiguously. By way of illustration, we provide an application to manufacturing employment in the Belgian provinces between 1995 and 2007.