Aluminium speciation: Variations caused by the choice of analytical method and by sample storage

We have compared a new FIA method (M1) for aluminium speciation in natural waters and a manual one based on one of Driscoll's proposals (M2). In synthetic solutions, aluminium's fluoro complexes were measured as ‘labile monomeric AP (Al _i ) by M2, but not as ‘quickly reacting Al’ (Al _qr ) by M1. Aluminium's complexes with Nordic Reference Humic Acid were measured neither as Al _i nor as Al _qr , and the same result was obtained for Al's citrato complexes. After excluding aluminium's fluoro complexes from Al _i , the results of the two methods agreed well for soil leaching samples and fairly well for natural water samples. Detection limits: 10μg L^?1 (ca. 0.4 μM) for both methods. Sample throughputs: M1∶66 injections h^?1; M2∶5 samples h^?1. Repeatabilities (RSD) on natural water samples: M1∶0.6–5.8% and M2 0.7–4.6%. Sample storage studies on soil solutions (FIA method) indicated that storage effects were ‘sample type specific’. A sample with a low level of Al _qr and a high DOC level (P2A) was more sensitive to storage than one with a high [Al] _qr and a low [DOC] (P2B^*). The decrease in [Al] _qr was statistically significant after 10 h (P2A) and 24 h (P2B^*), respectively. After 3 days' storage, [Al] _qr had decreased by some 40% in P2A, while the decrease in P2B^* was less than 10% after 8 days. The results of this part of the study also emphasize the importance of careful method standardization in sample storage studies.     

History and forest biodiversity of woodland key habitats in south boreal Sweden

Forest exploitation has destructed forest habitats in Fennoscandia during last centuries. Vital components of existing forest biodiversity have been identified as small (a few ha) woodland key habitats (WKHs). Many WKHs in boreal forest landscapes are assumed to represent remnant near-natural forests from before the phase of industrial forest exploitation. Thus, WKHs are supposed to (i) exhibit a low degree of exploitation, (ii) have old-growth characteristics and (iii) host Red-list species. Yet, WKHs’ history and biodiversity have not been systematically investigated. Thus, their conservation values remain unclear. This study investigates history and biodiversity of 15 WKHs in central Sweden with retrospective methods and field studies. We analyze (1) forest structure before, during and after the forest exploitation period, (2) existing biodiversity, i.e. species and structural elements, and (3) to what extent human activities (forestry) have influenced current biodiversity. Our results indicate that forest structure within the areas that currently are classified as WKHs has changed dramatically since the mid-19th century, when forests were unaffected by logging. The results suggest that fire-suppression during last century, gradually increased logging until mid-20th century and abandonment by modern forestry during the late 20th century, are main causes behind this transformation. Less than 10% of studied WKHs had biological features that resembled those of pristine boreal forests. Thus, most studied WKHs cannot be classified as near-natural or remnants of pristine forest. We suggest that the program for WKHs give more focus to pre-industrial forest structure, local historical aspects being seriously regarded and ecological restoration efforts being introduced.     

Nutrient and persistent pollutant deposition on the Bothnian Bay ice and snow fields

A study of atmospheric deposited nutrients and some persistent pollutants has been carried out on the ice and snow fields of the subarctic Bothnian Bay, the northernmost basin of the Baltic Sea. Total amounts of 600, 500 and 400 tons NO₃-N, NH₄-N and N_org-N, respectively are deposited in the snow while the corresponding amounts for P_tot-P is 40 tons. The corresponding amount for PCB and lindane are 1.0 and 0.2 kg, respectively. The measurements were carried out on the snow-covered ice four to six weeks old. A part of the deposited snow has been incorporated -into the snow-ice and an attempt to estimate its mean thickness and its amount of nutrients has been made. The total amounts now reach 1700, 1300 and 1100 tons of NO₃-N and NH₄-N and N_org-N, respectively in the snow and ice together. The results obtained support the use of land-based stations in estimates of seasonal atmospheric nutrient deposition to the Bothnian Bay. The observed concentrations of chloroorganic compounds correspond to those land-based observations reported from the same latitude in the northern hemisphere and reported in literature.     

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.     

Mercury in the Swedish environment — Recent research on causes,consequences and corrective methods

During the last decade a new pattern of Hg pollution has been discerned, mostly in Scandinavia and North America. Fish from low productive lakes, even in remote areas, have been found to have a high Hg content. This pollution problem cannot be connected to single Hg discharges but is due to more widespread air pollution and long-range transport of pollutants. A large number of waters are affected and the problem is of a regional character. The national limits for Hg in fish are exceeded in a large number of lakes. In Sweden alone, it has been estimated that the total number of lakes exceeding the blacklisting limit of 1 mg Hg kg-1 in 1-kg pike is about 10 000. The content of Hg in fish has markedly increased in a large part of Sweden, exceeding the estimate background level by about a factor of 2 to 6. Only in the northernmost part of the country is the content in fish close to natural values. There is, however, a large variation of Hg content in fish within the same region, which is basically due to natural conditions such as the geological and hydrological properties of the drainage area. Higher concentrations in fish are mostly found in smaller lakes and in waters with a higher content of humic matter. Since only a small percentage of the total flow of Hg through a lake basin is transferred into the biological system, the bioavailability and the accumulation pattern of Hg in the food web is of importance for the Hg concentrations in top predators like pike. Especially, the transfer of Hg to low trophic levels seems to be a very important factor in determining the concentration in the food web. The fluxes of biomass through the fish community appear to be dominated by fluxes in the pelagic food web. The Hg in the lake water is therefore probably more important as a secondary source of Hg in pike than is the sediment via the benthic food chain. Different remedy actions to reduce Hg in fish have been tested. Improvements have been obtained by measures designed to reduce the transport of Hg to the lakes from the catchment area, eg. wetland liming and drainage area liming, to reduce the Hg flow via the pelagic nutrient chains, eg. intensive fishing, and to reduce the biologically available proportion of the total lake dose of Hg, eg. lake liming with different types of lime and additions of selenium. The length of time necessary before the remedy gives result is a central question, due to the long half-time of Hg in pike. In general it has been possible to reduce the Hg content in perch by 20 to 30% two years after treatments like lake liming, wetland liming, drainage area liming and intensive fishing. Selenium treatment is also effective, but before this method can be recommended, dosing problems and questions concerning the effects of selenium on other species must be evaluated. Regardless how essential these kind of remedial measures may be in a short-term perspective, the only satisfactory long-term alternative is to minimize the Hg contamination in air, soil and water. Internationally, the major sources of Hg emissions to the atmosphere are chlor-alkali factories, waste incineration plants, coal and peat combustion units and metal smelter industries. In the combustion processes without flue gas cleaning systems, probably about 20 to 60% of the Hg is emitted in divalent forms. In Sweden, large amounts of Hg were emitted to the atmosphere during the 50s and 60s, mainly from chlor-alkali plants and from metal production. In those years, the discharges from point sources were about 20 to 30 t yr 1. Since the end of the 60s, the emission of Hg has been reduced dramatically due to better emission control legislation, improved technology, and reduction of polluting industrial production. At present, the annual emissions of Hg to air are about 3.5 t from point sources in Sweden. In air, more than 95% of Hg is present as the elemental Hg form, HgO⁰. The remaining non-elemental (oxidized) form is partly associated to particles with a high wash-out ratio, and therefore more easily deposited to soils and surface waters by precipitation. The total Hg concentration in air is normally in the range 1 to 4 ng m-3. In oceanic regions in the southern hemisphere, the concentration is generally about 1 ng m^?3, while the corresponding figure for the northern hemisphere is about 2 ng m-3. In remote continental regions, the concentrations are mainly about 2 to 4 ng m^?3. In precipitation, Hg concentrations are generally found in the range 1 to 100 ng L^?1. In the Nordic countries, yearly mean values in rural areas are about 20 to 40 ng L^?1 in the southern and central parts, and about 10 ng L^?1 in the northern part. Accordingly, wet deposition is about 20 (10 to 35) g km^?2 yr^?1 in southern Scandinavia and 5 (2 to 7) in the northern part. Calculations of Hg deposition based on forest moss mapping techniques give similar values. The general pattern of atmospheric deposition of Hg with decreasing values from the southwest part of the country towards the north, strongly suggests that the deposition over Sweden is dominated by sources in other European countries. This conclusion is supported by analyses of air parcel back trajectories and findings of significant covariations between Hg and other long range transported pollutants in the precipitation. Apart from the long range transport of anthropogenic Hg, the deposition over Sweden may also be affected by an oxidation of elemental Hg in the atmosphere. Atmospheric Hg deposited on podzolic soils, the most common type of forest soil in Sweden, is effectively bound in the humus-rich upper parts of the forest soil. In the Tiveden area in southern Sweden, about 75 to 80% of the yearly deposition is retained in the humus layer, chemically bound to S or Se atoms in the humic structure. The amount of Hg found in the B horizon of the soils is probably only slightly influenced by anthropogenic emissions. In the deeper layers of the soil, hardly any accumulation of Hg takes place. The dominating horizontal flow in the soils takes place in the uppermost soil layers (0 to 20 cm) during periods of high precipitation and high groun water level in the soils. The yearly transport of Hg within the soils has been calculated to be about 5 to 6 g km^?2. The specific transport of total Hg from the soil system to running waters and lakes in Sweden is about 1 to 6 g km^?2 yr¹. The transport of Hg is closely related to the transport of humic matter in the water. The main factors influencing the Hg content and the transport of Hg in run-off waters from soils are therefore the Hg content in soils, the transport of humic matter from the soils and the humus content of the water. Other factors, for example acidification of soils and waters, are of secondary importance. Large peatlands and major lake basins in the catchment area reduce the out-transport of Hg from such areas. About 25 to 75% of the total load of Hg of lakes in southern and central Sweden originates from run-off from the catchment area. In lakes where the total load is high, the transport from run-off is the dominating pathway. The total Hg concentrations in soil solution are usually in the range 1 to 50, in ground water 0.5 to 15 and in run-off and lake water 2 to 12 ng L^?1, respectively. The variation is largely due to differences in the humus content of the waters. In deep ground water with a low content of humic substances, the Hg concentration is usually below 1 ng L^?1. The present amount and concentrations of Hg in the mor layer of forest soils are affected by the total anthropogenic emissions of Hg to the atmosphere, mainly during this century. Especially in the southern part of Sweden and in the central part along the Bothnian coast, the concentrations in the mor layer are markedly high. In southern areas the anthropogenic part of the total Hg content is about 70 to 90%. Here, the increased content in these soils is mainly caused by long-range transport and emissions from other European countries, while high level areas in the central parts are markedly affected by local historical emissions, mainly from the chlor-alkali industry. When comparing the input/output fluxes to watersheds it is evident that the present atmospheric deposition is much higher than the output via run-off waters, on average about 3 to 10 times higher, with the highest ration in the southern parts of Sweden. Obviously, Hg is accumulating in forest soils in Sweden at the present atmospheric deposition rate and, accordingly, the concentrations in forest soils are still increasing despite the fact that the emissions of Hg have drastically been reduced in Sweden during the last decades. The increased content of Hg in forest soils may have an effect on the organisms and the biological processes in the soils. Hg is by far the most toxic metal to microorganisms. In some regions in Sweden, the content of Hg in soils is already today at a level that has been proposed as a critical concentration. To obtain a general decrease in the Hg content in fish and in forest soils, the atmospheric deposition of Hg has to be reduced. The critical atmospheric load of Hg can be defined as the load where the input to the forest soils is less than the output and, consequently, where the Hg content in the top soil layers and the transport of Hg to the surface waters start to decrease. A reduction by about 80% of the present atmospheric wet deposition has to be obtained to reach the critical load for Scandinavia.     

In vitro antioxidant activities of edible artichoke (Cynara scolymus L.) and effect on biomarkers of antioxidants in rats

Artichoke (Cynara scolymus L.), an edible vegetable from the Mediterranean area, is a good source of natural antioxidants such as vitamin C, hydroxycinnamic acids, and flavones. The antioxidant activity of aqueous-organic extracts of artichoke were determined using three methods: (a) free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH(*)) scavenging, (b) ferric-reducing antioxidant power (FRAP), and (c) inhibition of copper(II)-catalyzed in vitro human low-density lipoprotein (LDL) oxidation. In addition, the present study was performed to investigate the ability of the edible portion of artichoke to alter in vivo antioxidative defense in male rats using selected biomarkers of antioxidant status. One gram (dry matter) had a DPPH(*) activity and a FRAP value in vitro equivalent to those of 29.2 and 62.6 mg of vitamin C and to those of 77.9 and 159 mg of vitamin E, respectively. Artichoke extracts showed good efficiency in the inhibition in vitro of LDL oxidation. Neither ferric-reducing ability nor 2,2'-azinobis(3-ethylbenzothiazolin-6-sulfonate) radical scavenging activity was modified in the plasma of the artichoke group with respect to the control group. Among different antioxidant enzymes measured (superoxide dismutase, gluthatione peroxidase, gluthatione reductase, and catalase) in erythrocytes, only gluthatione peroxidase activity was elevated in the artichoke group compared to the control group. 2-Aminoadipic semialdehyde, a protein oxidation biomarker, was decreased in plasma proteins and hemoglobin in the artichoke-fed group versus the control group. In conclusion, the in vitro protective activity of artichoke was confirmed in a rat model.     

The response of normal and iron anemic calves to nasal infection with an attenuated strain of parainfluenza-3 virus.

Calves with experimentally induced iron deficiency anemia and normal calves, both groups deprived of colostrum, were exposed to intranasal instillation of an attenuated parainfluenza-3 virus strain.The calves became infected, but there was no difference in the clinical picture between the 2 groups of calves. Neither was there a difference in the humoral or local immune response to parainfluenza-3 virus.     

Fumaric and citric acids as feed additives in starter pig diets: effect on performance and nutrient balance

The effect of dietary citric acid (CA) and fumaric acid (FA) on pig weight gain (ADG) and gain/feed (G/F) was studied in two trials using 192 crossbred, 4-wk-old weaning pigs. Three dietary levels (0, 1.5 or 3.0%) of either FA (Trial 1) or CA (Trial 2) with or without an antibiotic supplement (110 mg chlortetracycline, 110 mg sulfamethazine and 55 mg penicillin/kg diet) formed six treatment combinations in each trial. These six diets were fed to two replicate pens of eight pigs each for a 4-wk period. In Trial 1, ADG was improved (P less than .01) during wk 1, and G/F was improved during wk 1 (P less than .01) as well as during wk 1 to 2 (P less than .05) for pigs consuming FA-supplemented diets. In Trial 2, CA had no beneficial influence on ADG during the 4-wk trial. However, feed intake during wk 1 was depressed (P less than .05) by adding CA, as was G/F during wk 1 to 2 (P less than .05). Based on these results, FA was selected to be used in a nutrient balance study. Twelve 4-wk-old weanling pigs were fed one of three diets: control (C), C + 1.5% FA, or C + antibiotic supplement (A). Diet digestible energy (DE), ME and N-corrected ME (MEN) were not different among treatments. Nitrogen balance, percentage N retained and apparent N digestibility were not affected by dietary treatment. Calcium balance and percentage of Ca retained were unaffected by diet.(ABSTRACT TRUNCATED AT 250 WORDS)