Humus status of different soils affected by pollution with fluorides from aluminum production in the Baikal region

The effect of pollution by fluorides from aluminum production on the humus status in different types of arable soils was studied in field experiments. They included modeling of a high pollution level by addition of NaF prevailing in industrial air emissions. The negative effect of fluorides on the humus status, related to an increase in the mobility of humic substances, was more pronounced in gray forest soil than in sod-meadow soil. This depended on the soil physicochemical properties determining the buffer capacity toward NaF and the content of water-soluble fluorides.     

Fires and pyrogenic successions in the forests of the south Baikal region

The southern coast of Baikal is characterized by the most humid climate in the Baikal region. Precipitation falls mainly on summer, thus reducing the actual of fire occurrence in mountain forests of the region. However, since 1989 the fire occurrence has been increased and disastrous crown fires have become more frequent, especially in the west. It is shown that fire occurrence is a function of the number, duration of rainless periods and monthly sums of rain precipitation, which have large amplitude of changes from year to year. Progressive pyrogenic successions in dark coniferous forests take place mostly without usual replacement by small-leaved tree species at the expense of successful regeneration of Pinus sibirica (in the western Khamar-Daban mountains) and Abies sibirica (in the central part) on the burnt areas during 15–25 years.     

Perspectives in chronobiology of air pollution

In a series of experiments, male and female Sprague Dawley rats, kept in light (L) from 06(00) to 18(00) alternating with darkness (LD 12:12) inhaled different concentrations of carbon monoxide (50-1,700 ppm) at each of two test times, 12 h apart. A decrease in flow of CO2 (VCO2) resulting from CO inhalation was greater in the active dark (D) than resting light (L) span. Experimental hypoxic mortality of male and female mice also shows circadian variations, being greater in the D than in the L span. Moreover, a difference of mortality was observed betwen hypoxic exposures performed at 12(00) (in LD or DL) and hypoxic exposures performed at 00(00) (in LD or DL). Such results await tests of any extent to which they model responses of human beings to air pollution. In human beings any external environmental circadian, circaseptan and circannual variations in air pollution as such may serve to variable extent as socioeconomic synchronizers of innate rhythms with a corresponding frequency, rather than as solely generators of time patterns in any physiopathologic response to air pollution.     

Post-logging organic matter recovery in forest ecosystems of eastern Baikal region

The dynamics of organic matter accumulated in the soil and main vegetation elements was analyzed for post-logging forest ecosystem succession series in eastern Baikal region. The phytomass was found to allocate up 63 and 50% of carbon in undisturbed Scots pine and fir stands, respectively. The post-logging phytomass contribution to the total carbon pool appeared to decrease down to 16% in Scots pine and 6% in fir stands. In Scots pine stands, carbon storage was determined to account for almost 70% of the initial carbon 60 years after logging. In 50- to 55-year-old fir stands, carbon recovered its initial pool only by 10%. Soil carbon recorded in recently logged Scots pine and fir sites appeared to be 5 and 16 times that accumulated in the phytomass, respectively. The ratio between phytomass carbon and soil organic matter recovered back to the prelogging level in Scots pine stands by the age of 50–60 years. While phytomass carbon also increased in fir stand of the same age, it did not reach the level of the control stand.     

Phytomonitoring of pulverized fuel ash leachates by the duckweed Lemna minor

The duckweed Lemna minor is one of the smallest vascular plants with a known strong capacity for metal accumulation. L. minor is proposed as a phytomonitor for coal ash drainage systems and for bio-assay studies directed to complexation and speciation. The duration of the experiment can be restricted to fourteen days; it is then possible to determine accurate data of differences in growth of the clone forming plant by using image processing techniques. Leaching of pulverized fuel ash (PFA) with acetic acid according to EPA instruction resulted in effects attributed to the acetic acid itself rather than to the metals in solution. Toxic effects of both leachates, natural and artificial, are discussed. The order of toxicity of metals studied so far in separate metal experiments is Cd > Cu > Zn > As(Arsenite) > Se(Selenite) > Ge > B > Mo.     

Isolation of a novel rickettsia from the tick Dermacentor silvarum in Baikal lake region

A new species of rickettsiae with unknown pathogenicity has been detected in ticks Dermacentor silvarum in the region of Baikal Lake. As revealed by the analysis of the primary structure of the gene fragment coding surface membrane protein of 190 kD (rOmpA), the nucleotide sequence of the rickettsiae under study is mostly similar to the sequences of R. sp. MOAa isolate (96%), R. sp. WB-8-2 (96%), R. massiliae strain GS (94%), Rickettsia BAR-29 (94%), R. rhipicephali (94%). Similarity with the sequence of R. sibirica has proved to be 91%. The data thus obtained indicate that the detected rickettsiae represent a new rickettsial species in the territory of East Siberia.     

Biotechniques for air pollution control

This paper gives an overview of present biological techniques for the treatment of off-gases and the techniques that are being developed at the moment. The characteristics, advantages, disadvantages, costs and application area are discussed and compared. Biological off-gas treatment is based on the absorption of volatile contaminants in an aqueous phase or biofilm followed by oxidation by the action of microorganisms. Biofilters, bioscrubbers and biotrickling filters are used for elimination of odour and bioconvertable volatile organic and inorganic compounds and are enjoying increasing popularity. This popularity is a result of the low investment and operational costs involved compared to physico-chemical techniques and the elimination efficiencies that can be obtained. The operational envelop is still extending to higher concentrations and gas flow rates (exceeding 200,000 m³ h^–1) and a broader spectrum of degradable compounds. Research and development on the use of membranes and the addition of activated carbon or a second liquid phase to the biological systems may lead to a more efficient elimination of hydrophobic compounds and buffering of fluctuating loads. Shorter adaptation periods can be obtained by inoculation with specialized microorganisms. Improved design and operation are made possible by the growing insights in the kinetics and microbiology and supported by the development of models describing biological off-gas treatment. In conclusion, biotechniques are efficient and cost effective in treating off-gases with concentrations of biodegradable contaminants up to 1–5 g/m³. They could play a justified and important role in air pollution control in the coming years.Abbreviations VOC volatile organic compound - NO _x gaseous oxides of nitrogen     

Epidemiological studies regarding the effects of air pollution

Studies on large samples of the population are an indispensable prerequisite for investigations into the validity and reliability of threshold levels stipulated for atmospheric pollutants purity under real conditions. Children represent suitable groups for such studies, also in the context of meaningful and effective prophylaxis. Epidemiological studies conducted over several years show that there are differences between the anthropometric, hematological and immunological parameters of subjects living in regions with major pollution loads and in so-called "clean air" regions. Conclusions are drawn regarding the work performed by national hygiene authorities, and a method is proposed for the continuation of epidemiological studies in qualitatively and quantitatively differently loaded regions as a contribution to establishing a uniform register of effects.