Florian Statescu

QUANTIFICATION OF EFFECTS PRODUCED BY THE EXTRACTION OF MINERAL AGGREGATES TOWARDS WATER BODIES

This paper presents the research performed in view of emphasizing the effects of mineral aggregates extraction on the geomorphological and hydraulic features of Moldova body of water. The effect on the geomorphological features was assessed by overlapping the cross profiles (22 profiles) and long profiles (2 profiles) from the entire area studied. These profiles were obtained by topographical measurements on the starting date (July 2013) and on the research end date, respectively (March 2015). The cross section opening underwent modifications of the riverbank edges between +3.30 m in section 9 and +74.80 m in section 6 and the river bed also went through a process of sinking of 0.70 m (section 1) and elevation of maximum 0.28 m (section 9). The mineral aggregates regeneration volume was 114084 m3 and the scouring volume was 141657 m3. An annual mineral aggregates deficit of 228 m3/ha/year resulted. The lowest water level descent was recorded in section 1 namely by 0.18 m and the highest decrease of the flowing velocity was recorded in section 4, namely 0.33 m/s.

Influence of some properties concerning water stable aggregates of saline soils

According to literature, aggregate stability of soils is influenced by: particle size and soil texture, soil structure, content of Ca2+ and Mg2+, mineral clay type, soil content of organic matter, soil processing degree. This paper aims to investigate the influence of some physical, microbiological and chemical properties of saline soil concerning water-stable aggregate. The hydro system stability of the aggregates appears in the specialized studies as having a positive correlation with microorganisms activity and thus with their behaviour in the soil. Our data support this theory, since according to our research there is a positive correlation between the percentage of stable aggregates and the amount of microorganisms. In samples from cultivated soil (noted in this paper by S), where the amount of microorganisms is higher, the percentage of water-stable aggregate is higher as well. In samples from uncultivated soil (noted in this paper by M), where the amount of microorganisms is lower, the percentage of water-stable aggregate is lower too. According to research studies and to the specialty literature, sodium is an element with a disruptive role on the stability of the aggregates. Our experimental data has shown that in samples from uncultivated soil (M), where sodium values are much higher, compared to samples from the cultivated soil (S), the percentage of water-stable aggregate is lower than the percentage of water-stable aggregate in the samples from the cultivated soil. Also, our results concerning porosity values ranging between 42.27% (the minimal value) to 49.86% the maximal value, show that these soils can be characterized as having low and very low porosity according to specialized literature. However, it must be taken into account the fact that in clay soils the porosity is very variable, depending on how the soil contracts, swells, disperses, compacts or cracks. In addition, the values describing the water permeability of the soil show that this characteristic for the control soil is small, the permeability coefficient k having values between 1.73 10-8 -7.19 10-8. For the cultivated soil, the permeability is medium, k having values between 4.97 10-7 - 7.83 10-8. Our data regarding soil physical properties, as well as the data about soil chemical properties that have been analyzed in this study show a weak quality of these soils, which cannot sustain a healthy crop with good economic yield.