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  • Author: Victoria Mocanu x
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Abstract

In forests, edaphic microbial communities are involved in litter decomposition and soil forming processes, with major contribution to humification, especially bacteria and fungi being responsible for the main ecosystem services fulfilled by the soil. Research has been carried out aiming to characterize the structure and diversity of microbial communities in the Rendzic Leptosols (WRB) under natural deciduous forest from Visterna, Babadag Plateau and to assess their contribution to ecosystem services provided by soil. The paper presents the results of quantitative estimations and taxonomic composition of soil and litter communities of heterotrophic bacteria and fungi, identification of cellulolytic species, as well as the microbial biomass and global physiological activities expressed as soil respiration potential. More than a half of bacterial species were common in litter and soil (SI=57.14%) and were represented by dominant species of fluorescent or non-fluorescent pseudomonads and Bacillus subtilis but no similarity was found between the two fungal communities. Fungal populations included cosmopolitan species, such as antagonists and strong cellulolytic representatives of genera Penicillium, Trichoderma, Mortierella, Chaetomium, Epicoccum, Aspergillus. Microbial density and microbial biomass presented the highest values in the litter (684 mg C x kg-1 d.s.) and in surface horizon Am1 of soil profile than in the bottom layers. The highest diversity was found in Am1 horizon (0-5 cm) H’=1.983 bits and ε=0.869 for cellulolytic community. Soil respiration reflected the intense physiological activity of microbiome, with high values associated to numerous effectives of bacteria and fungi especially in surface horizon. Microorganisms identified contribute to formation of soil by recycling of nutrients, cellulose decomposition, the synthesis of stable organic matter (humic acids), aggregation of soil particles, biological control of pathogens by antagonistic activity. They improve plant uptake of water and nutrients by forming symbioses (ectomycorrhizae), thus modelling the structure of vegetation.

Abstract

The soil degraded and changed by the anthropic activity must be monitored and the awareness of the intrinsic processes will allow a pertinent analysis of the effects of the application of the new technologies on the management and the sustainability of the soil.

Two natural and anthropic Phaeozems were analyzed from the point of view of chemical, microbiological characteristics, quality and composition of organic compounds.

Total values of microbial biomass and bacterial and fungal counts were generally twice higher in Calcaric Phaeozems than in Verti-Stagnic Phaeozems.

The content of humic precursors in Calcaric Phaeozems was quantitatively higher than that determined in Verti-stagnic Phaeozems, with a total content of phenols of 14.6mgGAExg−1d.m., polysaccharides and proteins of 97mgxg−1, respectivelly 16.6mgxl−1.

The ascending chromatograms showed specific distribution and higher density of the organic compounds in the CAFT sub-fraction of the Verti-stagnic Phaeozems. Pfeiffer specific chromatograms revealed an enzyme activity much higher than average at the Verti-stagnic Phaeozems, with a well-characterized functional diversity. The nutritional reserve appeared increased but poorly diversified in the Calcaric Phaeozems. Humification processes are intense, colloidal substances are present, the mineral component is very well integrated in the organic material at the Verti-stagnic Phaeozems and complex protein content is well revealed especially in the Calcaric Phaeozems.

Capillary dynamolysis reflected a characteristic pattern of Phaeozems soils, with particularities for each soil type, represented by colors, contours and particular forms of the specific structures developed.

Both soils presented good conditions for sustaining vegetation either natural or cultivated but results indicated that anthropic intervention determined a more dynamic mineralization of organic matter. Further monitoring of soil organic matter dynamics is needed and adjusting management practices for conservation of biodiversity and global ecosystem protection against the effect of anthropic intervention.

Abstract

The study aims to analyze the health effects caused by chronic exposure to elevated levels of nitrates in the water in order to improve prevention of some diseases. We analyze water quality from two villages of Constanta County in the period 2006-2012 and we take data about chronic diseases from family doctors of these localities. Analyzes on water samples were made in the laboratory of the Public Health Department. We found a significant increase of prevalence for chronic diseases in locality exposed to nitrates.