Nitrate reductase activity of needles of Norway spruce fumigated with different mixtures of ozone, sulfur dioxide, and nitrogen dioxide

Four-year-old spruce clones (Picea abies (L.) Karst.) cultivated in sand and provided with a complete nutrient solution, or a solution deficient in magnesium and calcium, were exposed to the pollutant mixtures SO(2)/NO(2), O(3)/NO(2), and O(3)/SO(2)/NO(2), at realistic concentrations for 32 weeks. Fumigation caused a slight increase of total N contents in current year needles, whereas in one-year-old needles N concentrations did not change. The response of nitrate reductase activity to pollutant stress depended on needle age and nutrient supply, respectively. In one-year-old needles fumigation resulted in a significant inhibition of enzyme activity, particularly in Mg and Ca deficient trees. The combination of all three components proved to be most effective in causing a decrease by 60% compared to the control. In contrast, nitrate reductase activity was stimulated in current year needles, especially by O(3)/NO(2) and O(3)/SO(2)/NO(2). Changes in the activity of nitrate and nitrite reductases are considered as a factor contributing to the high phytotoxic potential of pollutant combinations with NO(2).     

Energy and redox status, and carbon allocation in one- to three-year-old spruce needles

Metabolite pools were determined in lyophilized homogenates of one- to three-year-old needles from 13-year-old spruce trees. These were exposed in open-chambers for five consecutive years to SO(2) (30 microg m(-3)) and O(3) (50 to 180 microg m(-3)), singly and in combination. The samples were taken shortly before bud break (mid-March). The energy (ATP/ADP) and redox status (NAD(P)H/NAD(P)) increased with needle age. This increase was most pronounced in needles exposed to both pollutant gases. To evaluate carbohydrate metabolism, levels of starch, sugars (sucrose, fructose, glucose), sugar phosphates (dihydroxyacetone phosphate, glyceraldehyde 3-phosphate (triose phosphates, TP), fructose 6-phosphate, fructose 2,6-bisphosphate: F2,6BP) and 3-phosphoglyceric acid (PGA) were measured. The concentrations of starch, glucose, fructose and TP on a dry weight basis increased with needle age, while those of sucrose and F2,6BP decreased. Interestingly, the total amount of soluble sugars remained constant in needles from control chambers and large fluctuations mainly occurred after a single application of the pollutants. Needles from fumigated trees generally showed somewhat lower starch and sugar, and fructose 6-phosphate levels. The content of TP increased with needle age while that of sucrose and F2,6BP decreased. This inverse behavior was even more prominent in the presence of both pollutants and is discussed in the context of recent knowledge on the regulation of carbon partitioning. There was a significant increase in the ratio of TP/PGA in samples from the combined exposure treatments. This also indicates an increase in the redox charge and corroborates the data on both the redox status of the pyridine nucleotide system and the significantly increased ATP/ADP ratio. The results are indicative of a switch in metabolism, from anabolic to predominantly catabolic reactions, which is most pronounced in the samples fumigated with both O(3) and SO(2). The data are compared to those obtained from naturally exposed trees in the southern Black Forest (K?lbelescheuer/Haldenhof, near Freiburg, Germany).     

Exposure to chlorinated acetic acids: Responses of peroxidase and glutathione S-transferase activity in pine needles

During long-term exposure of pine (Pinus sylvestris L.) seedlings to trichloro- and monochloroacetic acids via root uptake or acid mist treatments, both substances were removed from the plant tissues by metabolic activity. None of the treated plants exhibited visible stress symptoms at the concentrations used. In addition, the exposure to both substances led to dramatic changes in the activity of xenobiotic detoxification enzymes (peroxidase and gluthatione S-transferase) in the needles of the plants.     

Influence of soil substrate and ozone plus acid mist on the pigment content and composition of needles from young Norway spruce trees

The influence of an ozone + acid mist treatment on photosynthetic pigments has been examined with the needles of the (Picea abies) clones 11, 14, 16, and 133 by spectrophotometric analysis of the total pigment extract and of single components upon HPLC separation (Part A), and in terms of a detailed pigment analysis of the 1987 and 1986 needles of clone 14 by TLC (Part B). Clone 14 had been already analysed prior to the onset of the experiment. At the end of the 14-month experiment, which incorporated frost events during a simulated winter period, neither symptoms corresponding to those of spruce Type I or IV decline, nor those of ozone damage could be observed. However, the 1986 needles of the trees on soil 1, which exhibit an adequate nutrient content, showed zonal chlorosis independently of the ozone + acid mist treatment. Analysis of variance of chlorophyll contents and needle ages showed a clear reduction to nearly 50% in the 1986 needles of clone 11, soil 1, and clone 16, soil 2. In contrast, clones 14 and 16 (soil 1) formed significantly more chlorophylls during the shorter exposure time in the 1987 flush. The detailed analysis of the individual pigment components of clone 14 needles provided no evidence for a destructive influence of the treatment on the chlorophylls, xanthophylls and beta-carotene in the two needle generations which had developed during the experiment, in spite of the distinct K deficiency of the 1986 needles of the trees on soil 2 and the common chlorosis of the needles of the trees on soil 1. The observed increase in violaxanthin content upon O(3)-treatment observed in clone 14 can be considered as an expression of the protective function of the xanthophylls against photooxidative processes. In conclusion, the observed differences in the chlorophyll and carotenoid contents are better correlated with the individual clone and soil character than with the ozone + acid mist treatment. Comparing the results of the pigment analyses of the needles the differences in the pigment concentrations reflect the N and K contents (Pfirrmann et al., 1990), which differ significantly between the clones. Thus it is not possible to pool the pigment data of all clones without considering the different nutrient levels.     

Alteration of physiological parameters in needles of cloned spruce trees (Picea abies (L.) Karst.) by ozone and acid mist

Three-year-old clonal spruce trees, kept in growth chambers, were treated with ozone and acid mist during a period of 14 months. One half of the trees were grown on an acidic sandy soil, the other half on a calcareous soil rich in carbonate. At the end of the fumigation period, carbohydrates (glucose, fructose, sucrose, raffinose, starch, glucose-1-phosphate and fructose-6-phosphate) and parameters of the energy status (ATP-, AdN-(ATP + ADP + AMP)- levels, ATP/ADP-ratios and adenylate-energy-charge-(AEC)-values) were determined in the current-year's needles. The results indicate that the metabolic status of a plant tissue is not only influenced by the nature of the air pollutants. Soil factors play an important role in metabolic changes within the plant and are thus of relevance in the manifestation of damage symptoms.     

Canopy leaching of nutrients and metals in a mountain spruce forest

Precipitation and throughfall fluxes of major ions, nutrients (C, N, P), and metals (Al, Fe, Mn), and the chemical composition of litter fall and living plant tissue in Norway spruce stands (the Bohemian Forest; Czech Republic), were used to evaluate how microbial processes and decay of plant tissue in canopies influence canopy leaching (CL) of elements. Proton exchange for Mg²⁺, Ca²⁺, and K⁺ in decaying biomass and co-transport of Ca²⁺ and K⁺ out of plant cells with organic acid anions were the most likely processes contributing to CL of base cations. The CL of total P and N (and also NO₃^?) was minor. Important proportions of the N and P mineral forms were transformed to organic forms by microbial processes (primary and bacterial production), with the respective CL of ?13.9 and 16.4 mmol m^?2 yr^?1 for NH₄⁺ and organic N, and ?0.33 and 0.22 mmol m^?2 yr^?1 for dissolved reactive P (DRP) and organic P. Most of particulate P and N in throughfall (～90%) originated from microbial DRP and NH₄⁺ transformations, but particulate C mostly came from the fragmentation of plant tissue (58%). Among metals, CL was not observed for Al, was small for Fe (0.3 mmol m^?2 yr^?1), and greatest for Mn (0.9 mmol m^?2 yr^?1) due to leaching from decaying tissue by acidic precipitation.     

Evaluating the size distribution characteristics and sources of atmospheric trace elements at two mountain sites: comparison of the clean and polluted regions in China

Size-resolved trace metal concentrations at two background sites were assessed during a 1-year observation campaign, with the measurements performed in parallel at two mountain sites, where Mt. Dinghu (DHS) located in the rural region of Pearl River Delta (PRD) and Mt. Gongga (GGS) located in the Tibetan Plateau region. In total, 15 selected trace elements (Mg, Al, K, V, Mn, Fe, Cu, Zn, As, Mo, Ag, Cd, Ba, Tl, and Pb) in aerosol samples were determined using inductively coupled plasma mass spectrometry (ICPMS). The major metals in these two mountain sites were Fe, K, Mg, and Ca with concentrations ranging between 241 and 1452 ng/m³, 428 and 1351 ng/m³, 334 and 875 ng/m³, and 376 and 870 ng/m³, respectively, while the trace metals with the lowest concentrations were Mo, Ag, Cd, and Tl with concentrations lower than 4 ng/m³ in DHS and 2 ng/m³ in GGS. The pronounced seasonal variability in the trace elements was observed in DHS, with lower concentrations in spring and summer and relatively high in winter and autumn, whereas seasonal variance of trace elements is hardly observed in Mt. Gongga. The size distribution pattern of crustal elements of Al, Mg, K, Ba, and Fe was quite similar in DHS and GGS, which were mainly found in coarse particles peaked at 4.7–5.8 μm. In addition, V, Mo, Ag, and Tl were also concentrated in coarse particles, although the high enrichment factor (EF?>?100) of which suggested anthropogenic origin, whereas trace metals of Cd, Mn, Zn, As, Cu, and Pb concentrated in fine mode particles. Specifically, these trace metals peak at approximately 1.5 μm in DHS, while those in GGS peaked at diameter smaller than 0.3 μm, indicating the responsible for long-range transport from the far urban and industrialized areas. Multivariate receptor model combined with the enrichment factor results demonstrated that the trace elemental components at these two background sites were largely contributed from the fossil fuel combustion (55.4% in DHS and 44.0% in GGS) and industrial emissions factors (20.1% vs. 26.5%), which are associated with long distance transport from the coastal area of Southeast China and the Northwestern India, respectively, as suggested by the backward air mass trajectory analysis. Local sources from soil dust contributed a minor variance for trace elements in DHS (9.7%) and GGS (13.8%), respectively.

     

Glutathione, glutathione S-transferase, and glutathione conjugates, complementary markers of oxidative stress in aquatic biota

Contaminants are ubiquitous in the environment and their impacts are of increasing concern due to human population expansion and the generation of deleterious effects in aquatic species. Oxidative stress can result from the presence of persistent organic pollutants, metals, pesticides, toxins, pharmaceuticals, and nanomaterials, as well as changes in temperature or oxygen in water, the examined species, with differences in age, sex, or reproductive cycle of an individual. The antioxidant role of glutathione (GSH), accompanied by the formation of its disulfide dimer, GSSG, and metabolites in response to chemical stress, are highlighted in this review along with, to some extent, that of glutathione S-transferase (GST). The available literature concerning the use and analysis of these markers will be discussed, focusing on studies of aquatic organisms. The inclusion of GST within the suite of biomarkers used to assess the effects of xenobiotics is recommended to complement that of lipid peroxidation and mixed function oxygenation. Combining the analysis of GSH, GSSG, and conjugates would be beneficial in pinpointing the role of contaminants within the plethora of causes that could lead to the toxic effects of reactive oxygen species.     

Phytoscreening and phytoextraction of heavy metals at Danish polluted sites using willow and poplar trees

The main purpose of this study was to determine typical concentrations of heavy metals (HM) in wood from willows and poplars, in order to test the feasibility of phytoscreening and phytoextraction of HM. Samples were taken from one strongly, one moderately, and one slightly polluted site and from three reference sites. Wood from both tree species had similar background concentrations at 0.5 mg kg^?1 for cadmium (Cd), 1.6 mg kg^?1 for copper (Cu), 0.3 mg kg^?1 for nickel (Ni), and 25 mg kg^?1 for zinc (Zn). Concentrations of chromium (Cr) and lead (Pb) were below or close to detection limit. Concentrations in wood from the highly polluted site were significantly elevated, compared to references, in particular for willow. The conclusion from these results is that tree coring could be used successfully to identify strongly heavy metal-polluted soil for Cd, Cu, Ni, Zn, and that willow trees were superior to poplars, except when screening for Ni. Phytoextraction of HMs was quantified from measured concentration in wood at the most polluted site. Extraction efficiencies were best for willows and Cd, but below 0.5 % over 10 years, and below 1?‰ in 10 years for all other HMs.     

Regional variation in surface properties of Norway spruce and scots pine needles in relation to forest decline

Measurements of leaf wettability (contact angle), amounts of epicuticular wax and of surface dust are reported for Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L) Karst) trees growing at 12 sites in Europe from SW Germany to NE Scotland. At each site, three year classes (current year, 1 and 2-year-old) of needles were sampled from the mid-crown of up to 12 trees. Trees were selected at random from two strata, those showing visible decline symptoms (i.e. loss of needles or discoloration) and those apparently healthy. Needles for analysis were taken from apparently healthy (green) shoots in both cases. There were no significant differences between 'declining' and 'healthy' trees within sites, suggesting that leaf surface properties reflect environmental exposure rather than plant response. There were significant differences between sites, particularly for Norway spruce, which may be related to environmental factors including air pollution. Contact angles were consistently smaller at low-altitude sites in Britain and The Netherlands than at high-altitude sites in Germany where forests show decline symptoms. Leaf wettability decreased (contact angles increased) with wax amount and increased with dust amount. Leaf surface properties integrate environmental influences over long periods, and may be useful in identifying sites 'at risk' of developing decline symptoms, but causal relationships cannot be deduced without further direct experimentation.     

Altitude profiles of total chlorinated paraffins in humus and spruce needles from the Alps (MONARPOP)

Chlorinated paraffins (CPs) are toxic, bioaccumulative, persistent, and ubiquitously present in the environment. CPs were analyzed in humus and needle samples, which were taken within the Monitoring Network in the Alpine Region for Persistent and other Organic Pollutants (MONARPOP) at sampling sites of 7 different altitude profiles in the Alps. Gas chromatography combined with electron ionization tandem mass spectrometry (EI-MS/MS) was used for the determination of total CPs (sum of short, medium and long chain CPs). CPs were found in all samples; the concentrations varied between 7 and 199 ng g⁻¹ dry weight (dw) and within 26 and 460 ng g⁻¹ dw in humus and needle samples, respectively. A clear vertical tendency within the individual altitude profiles could not be ascertained. Within all altitude profiles, elevated concentrations were observed in humus samples taken between 700 and 900 m and between 1300 and 1500 m. In the needle samples no similar correlation could be observed due to higher variation of the data.     

Comparisons of coarse-mode aerosol nitrate and ammonium at two polluted coastal sites

Direct atmospheric fixed-nitrogen deposition can contribute to eutrophication in coastal and estuarine waters and can be enhanced by heterogeneous reactions between gaseous atmospheric nitrogen species and aerosol sea salt, which increase deposition rates. Size-segregated aerosol samples were collected from two coastal sites: Weybourne, England and Mace Head, Ireland. Major-ion aerosol concentrations were determined and temporal patterns were interpreted with the use of air-mass back trajectories. Low levels of terrestrially derived material were seen during periods of clean, onshore flow, with respective concentration ranges for nitrate and ammonium of 0.47–220 and below detection limit to 340 nmol m⁻³. Corresponding levels of marine derived material during these periods were high, with sodium concentrations ranging from 39 to 1400 nmol m⁻³. Highest levels of terrestrially derived material were seen during polluted, offshore flow, where the air had passed recently over strong source regions of the UK and northern Europe, with concentration ranges of nitrate and ammonium of 5.6–790 and 9.7–1000 nmol m⁻³, respectively. During polluted flow ∼40–60% of the nitrate was found in the coarse mode (>1 μm diameter) and under clean marine conditions almost 100% conversion was seen. In addition, our data suggests strong evidence for dissolution/coagulation processes that also shift nitrate to the coarse mode. Furthermore, such processes are thought also to give rise to the size-shifting of aerosol ammonium, since significant coarse-mode fractions of this species (∼19–45%) were seen at both sites. A comparison of the relative importance of nitrate and ammonium in the overall dry deposition of inorganic fixed-nitrogen at each site indicates that at Weybourne the mass-weighted dry deposition velocity of the latter is around double that seen at Mace Head with its resultant contribution to the overall inorganic nitrogen dry flux exceeding that of nitrate.     

Fine particle measurements at two background sites in Korea between 1996 and 1997

Five intensive field measurements were carried out at two background sites in Korea; Kosan and Kangwha during spring, fall, and winters of 1996 and 1997 to investigate the characteristics of long-range transport of air pollutants in northeastern Asia. Fine particles (PM_2.5) were collected by low-volume samplers and the concentrations of major ions, organic and elemental carbons, and nitric acid were quantified. The concentrations of anthropogenic species in PM_2.5 measured at both sites were generally higher than those at other background areas, Nagano, Japan and San Nicolas Is., USA due to continental outflow of air pollutants, but lower than those at an urban background site, Qingdao, China. The major components of PM_2.5 were sulfate, organic carbon (OC), and ammonium for Kosan and sulfate, OC, ammonium, and nitrate for Kangwha. The major fractions of sulfate at both sites are non-sea-salts (nss) sulfate. Based on the relationship among major anthropogenic species, analysis of the nss sulfate to total nitrate molar ratios, and backward air parcel trajectories, it was found that fine particles measured at both sites during the measurement periods are mainly coming from China. At Kosan, the concentrations of anthropogenic species were higher when air parcels were coming from southern China than when air parcels were from northern China. At Kangwha, however, the differences of the concentrations were not statistically significant since most air parcels were from northern China and local effects are prominent.     

Simultaneous monitoring of profiles of polycyclic aromatic hydrocarbons in contaminated air with semipermeable membrane devices and spruce needles

Gaseous emissions of combusted electronic scrap, PVC, carpet and wood were monitored for polycyclic aromatic hydrocarbons (PAHs) by simultaneous use of semipermeable membrane devices (SPMDs) and shoots of spruce needles (Picea abies). It was found that phenanthrene, acenaphthylene and fluorene were the dominating PAHs in all samples. SPMDs and needles mainly sequestered PAH associated with the vapor phase. Particle-bound PAHs were only detected in small amounts, at which the needles tended to uptake more of these compounds in comparison to the SPMDs. Nevertheless, the logarithm of the concentrations of PAHs analyzed in both passive samplers after the same sampling period exhibited a significant linear correlation with correlation coefficients larger than 0.8073. SPMDs and spruce needles can complement each other in passive air sampling for compounds with a preference to the gas phase rather than aerosols.     

Simultaneous monitoring of PCDD/Fs and PCBs in contaminated air with semipermeable membrane devices and fresh spruce needles

The contaminated air with burning plastic floor and electronic scrap was monitored with semipermeable membrane devices (SPMDs) and fresh unpolluted spruce needles at the same time for polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) and polychlorinated biphenyls (PCBs). It was found that there were more polychlorinated dibenzofurans (PCDFs) than polychlorinated dibenzo-p-dioxins (PCDDs) collected from contaminated air. The total amounts of PCBs were much higher than that of PCDD/Fs, but the contribution of them to the WHO-TEQ was less than that of PCDD/Fs. Triolein-containing SPMDs can absorb much more PCDD/Fs and PCBs than spruce needles when they were exposed in contaminated air simultaneously. The logarithm of the concentrations of PCDD/Fs and PCBs in SPMDs and in spruce needles at the same sampling time exhibited a significant linear correlation, the correlation coefficients were larger than 0.86 for PCDD/Fs and 0.92 for PCBs. SPMDs and spruce needles are effective passive air sampler for PCDD/Fs and PCBs. SPMDs and spruce needles can complement each other in passive air sampling.     

Quantifying ozone uptake at the canopy level of spruce,pine and larch trees at the alpine timberline: an approach based on sap flow measurement

Micro-climatic and ambient ozone data were combined with measurements of sap flow through tree trunks in order to estimate whole-tree ozone uptake of adult Norway spruce (Picea abies), cembran pine (Pinus cembra), and European larch (Larix decidua) trees. Sap flow was monitored by means of the heat balance approach in two trees of each species during the growing season of 1998. In trees making up the stand canopy, the ozone uptake by evergreen foliages was significantly higher than by deciduous ones, when scaled to the ground area. However, if expressed per unit of whole-tree foliage area, ozone flux through the stomata into the needle mesophyll was 1.09, 1.18 and 1.40 nmol m(-2) s(-1) in Picea abies, Pinus cembra and Larix decidua, respectively. These fluxes are consistent with findings from measurements of needle gas exchange, published from the same species at the study site. It is concluded that the sap flow-based approach offers an inexpensive, spatially and temporally integrating way for estimating ozone uptake at the whole-tree and stand level, intrinsicly covering the effect of boundary layers on ozone flux.     

Evidence for potential impacts of ozone on Pinus cembra L. at mountain sites in Europe: an overview

We summarize what is known about the impact of ozone (O(3)) on Pinus cembra in the timberline ecotone of the central European Alps and the Carpathian Mountains. In the central European Alps exposure to ambient and two-fold ambient O(3) throughout one growing season did neither cause any visible injury nor affect the photosynthetic machinery and biochemical parameters in current to 1-year-old needles. By contrast, in the southern French Alps and in the Carpathians 1-year-old needles of Pinus cembra trees showed visual symptoms similar to those observed in O(3) stressed pine stands in southern California. For the southern French Alps the observed symptoms could clearly be attributed O(3) and differences in O(3) uptake seems to be the likely key factor for explaining the observed decline. For the Carpathians however, other reasons such as drought may not be excluded in eliciting the observed symptoms. Thus, the action of O(3) has always to be evaluated in concert with other environmental impacts, determining the tree's sensitivity to stress.     

Effect of tracer dyes on initial deposits and persistence of bacillus thuringiensis subsp. kurstaki toxin after application of two commercial formulations onto spruce trees

Abstract

The effect of two tracer dyes [Erio Acid Red (EAR) and Acid Black 48 (AB‐48)] on initial deposits and persistence of Bacillus thuringiensis subsp. kurstaki (Btk) toxin (delta‐endotoxin) was studied after spraying two commercial formulations, Foray® 48B and Foray® 76B, over potted white spruce [Picea glauca (Moench) Voss] seedlings, at a dosage rate of 30 billion international units (BIU) per ha. Spray was applied using a spinning disc atomizer calibrated to deliver droplet sizes similar to those utilized in ultra‐low‐volume (ULV) treatments in operational insect control programs. The sprayed seedlings were left outdoors at the Sault Ste. Marie laboratory for 18 days under natural conditions of sunlight, wind and rainfall. Initial deposits and persistence of delta‐endotoxin protein in spruce foliage were determined by immunoassay [enzyme linked immunosorbent assay (ELISA)] quantification of the delta‐endotoxin. The total protein (inactive plus active) and delta‐endotoxin (active protein) concentrations in the two formulations were determined by a gravimetric procedure and by ELISA respectively.

The initial deposit levels of the toxin on foliage were not markedly affected by the addition of either of the two tracer dyes, and showed only a narrow range of 1521 to 1625 ng/g foliage (fresh weight) for Foray 48B, and 1789 to 2056 ng/g for Foray 76B. However, the persistence of the toxin was significantly influenced by the presence of the dyes. The toxin persisted in foliage only for 7 d post‐spray When the EAR dye was added to Foray 48B, compared to 10 d when no dye was added. The average half‐life (DT₅₀) of disappearance was 17.4 h for Foray 48B with EAR, and 20.9 h when no dye was present. In contrast, the situation was reversed in Foray 76B, since the duration of persistence was 10 d when EAR was added to Foray 76B, compared to 7 d when no dye was added. The average DT₅₀ was 27.9 h for Foray 76B with EAR, and 22.2 h without the dye. Persistence was the longest (14 d) when the AB‐48 dye was added to Foray 76B, and the DT₅₀ was 44.9 h.     

Environmental impact and recovery at two dumping sites for dredged material in the North Sea

The environmental impact and recovery associated with the long and uninterrupted disposal of large volumes of moderately contaminated dredged material from the port of Rotterdam was studied at nearby dumping sites in the North Sea. Observations were made on sediment contamination, ecotoxicity, biomarker responses and benthic community changes shortly after dumping at the 'North' site had ceased and at the start of disposal at the new dumping site 'Northwest'. During the period of dumping, very few benthic invertebrates were found at the North site. Concentrations of cadmium, mercury, polychlorinated biphenyls (PCBs), polyaromatic hydrocarbons (PAHs) and tributyltin (TBT) in the fine sediment fraction (<63 microm) from this site were 2-3 times higher than at the reference site. In four different bioassays with marine invertebrates the sediments showed no acute toxic effects. In tissue (pyloric caeca) of resident starfish Asterias rubens, residual levels of mercury, zinc, PCBs and dioxin-like activity were never more than twice those at the reference site. Four different biomarkers (DNA integrity, cytochrome P450 content, benzo[a]pyrene hydroxylase activity and acetylcholinesterase inhibition) were used on the starfish tissues, but no significant differences were found between North and the reference site. Minor pathological effects were observed in resident dab Limanda limanda. One year after dumping had ceased at the North site, a significant increase in the species richness and abundance of benthic invertebrates and a concomitant decrease in the fine sediment fraction of the seabed were observed. After 8.2 million m3 of moderately contaminated dredged material had been dumped at the new dumping site Northwest, the species richness and abundance of benthic invertebrates declined over an area extending about 1-2 km eastwards. This correlated with a shift in sediment texture from sand to silt. The contamination of the fine sediment fraction at the Northwest location doubled. It is concluded that marine benthic resources at and around the dumping sites have been adversely affected by physical disturbance (burial, smothering). However, no causal link could be established with sediment-associated contaminants from the dredged spoils.     

Impact of atmospheric deposition on the status of planted Norway spruce stands: A comparative study between sites in southern Sweden and the northeastern Czech Republic

Six Norway spruce stands (Picea abies L.) in southern Sweden and six in the northeastern Czech Republic, 12 stands in total, were selected for short-term investigations during the summer and autumn of 1991. In each of the plots, an assessment of foliar damage and dendrometric measurement of the trees was made. Soil and leaf samples were collected and analyzed for their chemical composition. After statistical evaluation of the most important correlations, it was concluded that the main cause of tree damage in both countries was through the acidification of the soils. In both countries, but especially in the Czech Republic, heavy metal accumulation in the humus layer was observed. The main results of the study were the discovery of the similarity of damage processes in the two countries, despite the differences in their geographic location and ambient air pollution levels