The Use of Natural Taraxacum officinale Wigg. Populations for Assessing the State of Technogenically Disturbed Areas

Russian Journal of Ecology -     

Winter-spring essential reorganization of cell proliferation in the digestive tract epithelia in the mussel Crenomytilus grayanus

A study of the seasonal dynamics of cell proliferation in the digestive tract epithelia of the mussel Crenomytilus grayanus (Bivalvia) collected in the Sea of Japan between 1971 and 1984 revealed two opposite states so far unknown for marine molluscan tissues: proliferative resting in winter and a following outburst of cell division in spring. In winter and early spring (at water temperatures below or near 0°C), mitotic figures in the lining epithelia of labial palps and intestine strongly reduced in number and later almost disappeared (February-March); DNA-synthesizing cells in these epithelia on thymidine radioautographs became sparse and only a restricted number of new cells entered the cell cycle. A proliferation block was relieved at the beginning of April (at a temperature of 2 to 4°C): an initiation of a many-fold increase in the mitotic index and some increase in the ³H-T-labelled nuclei index and their advance to the maximum in late April to May (up to more than 0.2 and 5 to 6%, accordingly) were found. In late spring (at temperatures of 5 to 10°C), a striking rise in the number of cells entering the cell cycle was observed with a probable acceleration of the cycle proper. Both seasonal states of cell proliferation — a deep depression and outburst, established in the winter-spring period are interpreted as essential events in the life cycle of the mussel studied.     

Nitrogen concentrations in mosses indicate the spatial distribution of atmospheric nitrogen deposition in Europe

In 2005/6, nearly 3000 moss samples from (semi-)natural location across 16 European countries were collected for nitrogen analysis. The lowest total nitrogen concentrations in mosses (<0.8%) were observed in northern Finland and northern UK. The highest concentrations (≥1.6%) were found in parts of Belgium, France, Germany, Slovakia, Slovenia and Bulgaria. The asymptotic relationship between the nitrogen concentrations in mosses and EMEP modelled nitrogen deposition (averaged per 50 km × 50 km grid) across Europe showed less scatter when there were at least five moss sampling sites per grid. Factors potentially contributing to the scatter are discussed. In Switzerland, a strong (r² = 0.91) linear relationship was found between the total nitrogen concentration in mosses and measured site-specific bulk nitrogen deposition rates. The total nitrogen concentrations in mosses complement deposition measurements, helping to identify areas in Europe at risk from high nitrogen deposition at a high spatial resolution.     

Runoff fluctuations in the Selenga River Basin

Regional Environmental Change - The Selenga River has historically provided 50% of the total freshwater water input to the Lake Baikal, transporting substances and pollutants that can considerably...     

First Europe-wide correlation analysis identifying factors best explaining the total nitrogen concentration in mosses

In this study, the indicative value of mosses as biomonitors of atmospheric nitrogen (N) depositions and air concentrations on the one hand and site-specific and regional factors which explain best the total N concentration in mosses on the other hand were investigated for the first time at a European scale using correlation analyses. The analyses included data from mosses collected from 2781 sites across Europe within the framework of the European moss survey 2005/6, which was coordinated by the International Cooperative Programme on Effects of Air Pollution on Natural Vegetation and Crops (ICP Vegetation). Modelled atmospheric N deposition and air concentration data were calculated using the Unified EMEP Model of the European Monitoring and Evaluation Programme (EMEP) of the Convention on Long-range Transboundary Air Pollution (CLRTAP). The modelled deposition and concentration data encompass various N compounds. In order to assess the correlations between moss tissue total N concentrations and the chosen predictors, Spearman rank correlation analysis and Classification and Regression Trees (CART) were applied. The Spearman rank correlation analysis showed that the total N concentration in mosses and modelled N depositions and air concentrations are significantly correlated (0.53 ≤ r_s ≤ 0.68, p < 0.001). Correlations with other predictors were lower than 0.55. The CART analysis indicated that the variation in the total N concentration in mosses was best explained by the variation in NH₄⁺ concentrations in air, followed by NO₂ concentrations in air, sampled moss species and total dry N deposition. The total N concentrations in mosses mirror land use-related atmospheric concentrations and depositions of N across Europe. In addition to already proven associations to measured N deposition on a local scale the study at hand gives a scientific prove on the association of N concentration in mosses and modelled deposition at the European scale.