Concentrations of long-lived artificial radionuclides in the moss-lichen cover of mountain plant communities

Specific features of⁹⁰Sr and¹³⁷Cs accumulation in individual lichen species and in the moss-lichen cover of plant communities were studied in some mountain ranges of the Polar and Northern Urals. The results showed that the amounts of radionuclides in lichens and mosses of mountain plant communities are at the level characteristic of the moss-lichen cover of flat ecosystems, and their accumulation depends on⁹⁰Sr and¹³⁷Cs input with the global radioactive fallout. The radionuclide contents in lichens and mosses sampled from different mountain rocks, slopes, and elevations fluctuate around this level. The differences depend both on the structural and functional properties of plants and on the climatic and ecological features of their environment.     

Current Contents of 90Sr and 137Cs in the Moss–Lichen Cover of Piedmont and Mountain Landscapes of the Northern Urals

The contents of long-lived artificial radionuclides, ⁹⁰Sr and ¹³⁷Cs, were determined in lichens and mosses of different taxa and in the samples of moss–lichen cover taken from the mountain and lowland plant communities of the Northern Urals. The effects of Chernobyl fallout and the dynamics of radionuclide contents in lichens and mosses were analyzed. The concentration of ¹³⁷Cs in the moss–lichen cover was higher in the mountain ecosystems than in the lowland plant communities.     

Effect of cooking on radionuclide concentrations in waterfowl tissues

Twenty-four commercially raised mallard ducks (Anas platyrhynchos) were released at reactor radioactive leaching ponds in southeastern Idaho and subsequently collected 56 to 188 days later. Liver, gizzard and carcass were analyzed for radionuclide concentrations before and after cooking. Significant decreases (P < 0·05) in ¹³⁷Cs, ¹³⁴Cs, ⁶⁰Co and ^110mAg concentrations in carcass and liver samples occurred after cooking. Radionuclide concentrations in gizzard showed no significant change in radionuclide concentrations after cooking. Cesium-134 and ¹³⁷Cs concentrations decreased by 27% in carcass after cooking and reduced the dose commitment to man by that amount if only the carcass was consumed. No reduction in dose is expected if the carcass and juice were consumed.     

Effect of Extractive Compounds from Lichens and Mosses on the Development of Basidiospores and Mycelium of Tinder Fungus

It has been shown that extracts from the thalli of lichens and mosses have an adverse effect on the viability and germination of spores and suppress the asexual reproduction of the haploid mycelium. The dikaryotic mycelium and its conidial spores are more resistant to the action of extractive compounds from lichens and mosses.     

Natural radionuclide concentrations in two phosphate ores of east Algeria

Ore is considered as an important source of many elements such as the iron, phosphorus, and uranium. Concerning the natural radionuclides, their concentrations vary from an ore to other depending on the chemical composition of each site.In this work, two phosphate ores found in East of Algeria have been chosen to assess the activity concentration of natural radionuclides represented mainly by three natural radioactive series ²³⁸U, ²³⁵U and ²³²Th, and the primordial radionuclide ⁴⁰K where they were determined using ultra-low background, high-resolution gamma-ray spectroscopy.The measured activity concentrations of radioactive series ranged from 6.2 ± 0.4 to 733 ± 33 Bq.kg⁻¹ for the ²³²Th series, from 249 ± 16 to 547 ± 39 Bq.kg⁻¹ for the ²³⁸U series, around 24.2 ± 2.5 Bq.kg⁻¹ for the ²³⁵U series, and from 1.4 ± 0.2 to 6.7 ± 0.7 Bq.kg⁻¹ for ⁴⁰K.To assess exposure to gamma radiation in the two ores, from specific activities of ²³²Th, ⁴⁰K and ²²⁶Ra, three indexes were determined: Radium equivalent (Ra_eq), external and internal hazard indexes (H_ex and H_in), their values ranged from 831 ± 8 to 1298 ± 14 Bq.kg⁻¹ for Ra_eq, from 2.2 ± 0.4 to 3.5 ± 0.7 Bq.kg⁻¹ for H_ex, and from 4.2 ± 0.7 to 4.5 ± 0.7 Bq.kg⁻¹ for H_in.     

The role of floods in the Long-term dynamics of geobiont and chortobiont communities on islands of the Kuibyshev Reservoir

Interannual changes in geobiont and chortobiont abundance on the islands of Kuibyshev Reservoir are largely determined by flood conditions, because the seasonal average abundance of many taxa is negatively correlated to the water level in May and June. Floods influence the abundance of these animals both directly and indirectly, through biocenotic connections and some aspects of behavior. Long-term positive trends are observed in the abundance of many species. The hypothesis is proposed that this increase in the abundance of geobionts and chortobionts is a consequence of adaptation processes in these communities, which are stimulated by the flood regime of the reservoir.     

The influence of a coal-fired power plant operation on radionuclide concentrations in soil

Fifty-two soil samples in the vicinity of a coal-fired power plant (CFPP) in Figueira (Brazil) were analyzed. The radionuclide concentration for the uranium and thorium series in soils ranged from <9 to 282 Bq kg(-1). The range of 40K concentration in soils varied from <59 to 412 Bq kg(-1). The CFPP (10 MWe) has been operating for 35 years and caused a small increment in natural radionuclide concentration in the surroundings. This technologically enhanced natural radioactivity (TENR) was mainly due to the uranium series (234Th, 226Ra and 210Pb) and was observable within the first kilometer from the power plant. The CFPP influence was only observed in the 0-25 cm soil horizon. The soil properties prevent the radionuclides of the 238U-series from reaching deeper soil profiles. The same behavior was observed for 40K as well. No influence was observed for 232Th, which was found in low concentrations in the coal.     

Dynamics of heavy metal accumulation in thalli of the epiphytic lichen Hypogymnia physodes

A sequential extraction procedure was used to study localization of heavy metals in thalli of the lichen Hypogymnia physodes (L.) Nyl. growing under conditions of chronic aerotechnogenic pollution in the Middle Urals. Trends in the seasonal dynamics of metal contents in the thalli were revealed. The dynamics of metal accumulation was also studied in the thalli brought to the polluted zone from the background environment. After one year, the extra-and intercellular contents of most metals in these transplants approached those in the aboriginal thalli and in some cases (intracellular content of cadmium) exceeded them.     

Long-term variations of folic acid concentrations in the Northern Adriatic

Folic acid (FA), which belongs to B-group vitamins has recently been recognized as possible nutrient for some phytoplankton species (a diatom Phaeodactylum tricornutum). The beneficial role of FA in human health is widely documented. In some countries food fortification with FA has already become mandatory. FA is also used under commercial name of Dosfolat for the treatment of industrial and domestic wastewaters. This is an exploratory study on seasonal and depth variability of FA concentrations in the Northern Adriatic Sea (station 101-max depth 30 m, under the Po River influence). Seawater samples were analysed in the period from February 1998 to February 2003 based on monthly determinations. Those preliminary findings showed that in the upper layer (10 m) FA concentrations were in the range from 0.1 to 28 nM. In the lower layer (20-30 m) FA concentrations were in the range from 0.1 to 12 nM. It was found that phytoplankton and microorganisms which are responsible for the production of FA in the Northern Adriatic (Station 101) were situated at the depth from 5 to 10 m. The observed water column and seasonal distributions depended on a sensitive balance between the production and the consumption of FA.     

Multi-scale land cover dynamics of semiarid scrubland in Baja California,Mexico

Land use and cover changes trigger multi-factorial responses with tangible and intangible effects. Driving forces governing changes are scale-, place- and time-dependent; because of their complexity, a multi-scalar analysis is required to determine conjoint causation. Studies using multi-scalar approach in semiarid scrubland ecosystems are scanty. This paper investigates land use changes on the largest semiarid scrubland ecosystem of Mexico, the Baja California Peninsula, using a multi-scalar analysis approach. It further provides insight into the likely underlying causes for land use trends. Multi-temporal databases were compiled for 1978, 1990, 2000 and 2003 from various sources; population was projected for the same years. Land cover processes were validated through intensive fieldwork. Map overlapping with the aid of geographic information systems allowed computation of land cover transformation rates. New algorithms were developed to better understand land cover trends. Multi-variate analysis was also performed to provide a synthetic statistical overview. Results showed that land cover change occurred at different times, at variable scales, due to distinct drivers. As a consequence, the current regional scenario has been shaped by distinguishable socio-economic changes. The semiarid scrubland ecosystems in the Baja California Peninsula experienced contrasting trends detectable only at site and local scales. Regionally, the replacement of original vegetation (scrubland) for other land cover category is following trends similar to those in the rest of Mexico and most semiarid ecosystems worldwide. These findings support the hypothesis that land use and cover changes must be analyzed at different times and scales to deeply understand underlying forces.     

Long-term dynamics of summer bird communities in the Arkaim reserve

Nesting bird communities of individual habitat types in the Arkaim reserve are formed every year under the influence of nonrandom factors. Their qualitative and quantitative composition may gradually shift in a certain direction, but more often it remains relatively stable over several years and then makes an abrupt transition into a different state. The strongest effect on the dynamics of these communities has been exerted by progressive succession following the assignment of special protection status to the Arkaim area. The effects of fires and other elemental factors are also significant.     

Long-term abundance dynamics of coastal zooplankton in the Gulf of Riga

The dynamics of three most abundant mesozooplankton species in the coastal zone of the Gulf of Riga--Bosmina longispina, Synchaeta baltica, Keratella quadrata--is analyzed to detect the regulating environmental factors. The only significant downward trend of species abundance was found for S. baltica in autumn. Statistically significant correlation was estimated only between the summer salinity and the abundance of B. longispina. K. quadrata though showed a negative correlation with summer salinity. The abundance of S. baltica had only nonsignificant correlations with the environmental factors. The abundance of coastal mesozooplankton species is determined by the combination of hydrological regime, predation pressure, benthic conditions and the success of living strategy. The change of fresh- and saline water masses at the coastal areas supplies sufficient food amount but can cause decline in hatching abilities.     

Mass balance approach to estimating radionuclide loads and concentrations in edible fish tissues using stable analogues

Humans can consume a number of types of biota tissues, which have varying propensities to accumulate radionuclides. As a result, depending upon the biota species, the radionuclide and the tissue under consideration, it may be necessary to estimate the percent radionuclide load in specific edible tissues, and in cases where whole organisms are consumed, to estimate the radionuclide load in the whole body of an organism, based on data that have been collected for individual tissues. To accomplish this, data were compiled that can be used to estimate the partitioning patterns and percent loads of various groups of elements in edible tissues of freshwater fishes. General trends in partitioning, such as those provided in this paper, can be used to predict radionuclide transfer to humans and the corresponding potential radiological dose to humans via dietary pathways, in this case following the consumption of fish.     

Long-term population dynamics of ixodid ticks and development of tick-borne encephalitis foci under conditions of the middle taiga subzone

Long-term (1995–2003) population dynamics of ixodid ticks and their main hosts (small mammals) and conditions providing for the formation of tick-borne encephalitis (TBE) foci were studies in the middle taiga subzone (Karelia). The results show that the bank vole (Clethrionomys glareolus Schr.) is the main host for the larvae and nymphs of Ixodes persulcatus Schulze, 1930 and for the larvae, nymphs, and adult individuals of I. trianguliceps Birula, 1895. The proportion of ticks feeding on this species (relative to their total number) reaches 63.3% (64.0% of I. persulcatus and 61.1% of I. trianguliceps). Activity of a TBE focus is determined primarily by the abundance of bank voles of older age groups.