Total airborne Hg as well as black particles (soot) were monitored in a number of clean air areas in Sweden. For some of the sampling sites, back trajectories for air movements at 850 mb were provided by the Norwegian Meteorological Institute. It is shown that the total Hg in air may be divided into two fractions. The most important one may be considered to be a background and is probably the result of re-emission of Hg by the ground and by natural water. The other fraction is highly dependent on wind direction in the same way as black particles. This fraction seems to be of anthropogenic origin.

Chrome tannery sludge applied to agricultural land may have benefits in terms of added N for crop growth. An experiment was designed to compare tannery waste with commercial N fertilizer and investigate the potential of the waste as an alternative or supplement to commercial fertilizer. Soils with 38% and 7% orggganic C and N content of 1.3% and 0.2% respectively, were amended with lime, commercial N fertilizer, or tannery sludge containing 1.6% Cr. A portion of the tannery waste was supplemented with additional Cr('3+) salt before adding to the soils. The amended soils were analyzed for total Cr, ammonium acetate extractable Cr, selected nutrient and trace element concentrations. The tannery sludge increased soil pH, total Cr and N, S, Ca, P, Mg, and Na concentrations. DTPA extractable Cr increased only when Cr('3+) salt was added, but soil pH decreased markedly. Electroconductivity of the soils increased with the waste application rate and, at the highest rate of Cr('3+) salt addition, far exceeded values recommended for successful crop production. The acidic, high salt conditions complicated interpretation of the Cr('3+) salt addition results. Tannery sludge may be applied to agricultural land as a fertilizer amendment without adversely affecting soil chemical properties. The amount and frequency of application should be determined by (1) total and available N, (2) total salt content, (3) total and available Cr, and (4) soil organic matter.

Soil samples were collected to a depth of 0 to 10 cm from several sites near a secondary Pb smelter during the summer of 1976 in order to determine heavy metal concentrations of soil and enumerate soil microorganisms and earthworms. Chemical analyses indicated that abnormally high concentrations of Pb, As, Cd, and Cu decreased with increasing distance from the source and population counts of bacteria, actinomyces, fungi, nematodes and earthworms increased with increasing distance from the smelter. The negative correlation coefficients between bacteria, actinomyces, fungi, and nematodes and the level of Pb, As, Cd, and Cu in the soil were statistically significant. The microflora of the contaminated soil was altered and the marked quantitative reduction or elimination of organisms were attributable to heavy metal pollution emission from the secondary Pb smelter.

An important consequence of acidification is the mobilization of Al from the edaphic to the aquatic environment. Elevated Al levels in acidic waters may be toxic to fish. Eggs, larvae, and postlarvae of white suckers (Catostomus commersoni) and brook trout (Salvelinus fontinalis) were exposed in laboratory bioassays to pH levels 4.2 to 5.6 and inorganic Al concentrations of 0 to 0.5 mg/l. Aluminium toxicity varied with both pH and life history stage. At low pH levels (4.2 to 4.8), the presence of Al (up to 0.2 mg/l for white suckers; 0.5 mg/l for brook trout) was beneficial to egg survival through the eyed stage. In contrast, Al concentrations of 0.1 mg/l (for white suckers) or 0.2 mg/l (for brook trout) and greater resulted in measurable reductions in survival and growth of larvae and postlarvae at all pH levels (4.2 to 5.6). Aluminium was most toxic in over-saturated solutions at pH levels 5.2 to 5.4. The simultaneous increase in Al concentration with elevated acidity must be considered to accurately assess the potential effect of acidification of surface waters on survival of fish populations.

Long range transport of episodic concentrationns of 0(,3) into the Appalachian Mountains of Virginia was recorded in the summer season of 1979 and 1980. Continuous monitoring of 0(,3) indicated monthly averages of 0.05 ppm 0(,3) and several periods averaged approx. 0.08 ppm 0(,3). Open-top chambers were used to test the effect of ambient doses of the pollutant on the growth of 8 planted forest tree species native to the area. Height growth was suppressed for all species at the end of the second growing season when grown in open plots (no chamber) and ambient chambers compared to those grown in charcoal-filtered air supplies chambers. Height growth trends of open ambient chamber filtered air chamber were consistent. Virginia pine and green ash were significantly taller (p

Equations describing particle transport to surfaces by diffusion, interception, impaction, and sedimentation have been used to preduct dry deposition onto five wild grass canopies. Detailed measurements of plant height and spacing, width of stems, leaves, and inflorescences, and wind data collected within and above each canopy have been applied as model input data. The resulting curves of deposition velocity versus particle diameter have then been used with size distribution data from the literature for Pb and sulfate to predict overall dry deposition. Results of these calculations suggest a wide range of dry deposition velocities of 0.05 to 1 cm/s for these species, the variation resulting from differences in surface structure and size distribution characteristics. At least 40% of the mass deposition of lead and sulfate results from the largest 10% of the airborne material.

This study presents data concerning long-term trends after neutralization of four acidified lakes in two regions on the Swedish west coast. Neutralization was achieved by a di-Ca-silicate with 52% CaO and about 11.5% MgO. Between 61 and 74% of the spread lime product dissolved during a 5 to 7 yr period. The liming increased pH, from a range of 4.5 to 5.2 to near neutral and restored alkalinity in the range of 0.2 to 0.3 meq/l and the Ca-content became 3 to 4 times higher than before liming. In two lakes transparency decreased significantly presumably due to changed phytoplankton composition. These changes successively declined due to dilution and continuous acid loading. The changes in water chemistry and development of stocked brown trout (Salmo trutta) populations initiated biotic changes. Phyto- and zooplankton communities reacted both instantly and later with successions in species composition. Changes of benthic macroinvertebrate species occurred over several years, but some pelagic species, e.g. corixids were rapidly reduced due to predation of fish. Observed changes were predominantly due to expanding populations of species present at very low abundances even during acid state of the lakes. Some organisms found during preacid state of the lakes did not establish new populations and this process may need a prolonged time with favourable conditions. Reacidification towards the end of the study period significantly stressed the brown trout population and also favoured expansion of the filamentous alga Mougeotia sp. and Sphagnum sp. that almost vanished during the first year after liming. Decreasing concentration of total P was not influenced by neutralization and may be mostly dependent on negative changes in the soils surrounding the lakes. If generally valid, this process may be an important factor for the oligotrophication of lakes in areas where acid deposition is high.

Effects of soil acidity on microbial decomposition of organic matter and transformation of N in an acid forest soil were investigated. In the oak-leaf-amended pH-adjusted acid soils, CO(,2) production in 14- and 150-day preincubated samples decreased by about 6 and 37%, respectively. In the control (unamended) acidified soils, reductions in CO(,2) production of 14% in 14-day preincubated samples and of 52% in 150-day samples were observed. Ammonia formation in the pH-adjusted acid soil was about 50% less than in the naturally acid soil. Increased rates of ammonification and nitrification were observed in the pH-adjusted neutral soil. Little autotrophic and heterotrophic nitrifying activity was detected in naturally acid and acidified forest soils. The rate of denitrification was rather slow in acid soils, and at greater acidities N(,2)O was the predominant end product. The abundance of N-fixing free-living bacteria was very low in acidic and acidified forest soils, and N gains by asymbiotic bacterial fixation in an acid forest ecosystem may be insignificant. These results suggest that further acidification of acid forest soils by addition of H(,2)SO(,4) or by acid precipitation may lead to significant reductions in the leaf litter decomposition, ammonification, nitrification, and denitrification and thus reduce nutrient recycling in the forest ecosystem.