Search

Selenium mobility in soil depends on a multitude of physical and chemical factors. The present paper highlights the selenium solubilization degree out of the total soil content in relation with its agrochemical properties. Soils samples were considered collected from different agricultural areas of the Country, with or without certain natural handicaps, from soils under industrial impact and long term agrochemical experiments. The selenium solubilization percentages out of the soil total content ranged between 3.57 and 8.15%. No solubilization percentage was calculated for Central and Southern Dobrudja and the South-Eastern Romanian Plane, because the total selenium quantities in these areas are lower and mobile selenium values are very low. The statistical analysis of the calculated percentage values highlighted homogeneous areas and areas with a higher scattering degree. Thus, in agricultural land, in acknowledged agrarian areas and in long term agricultural experiments, the percentage values are better grouped, showing (expectable) soil homogeneousness, on one hand, and a significant soil selenium supply and its adequate solubilization for plant nutrition, on the other. The most scattered values occurred in the Călmăţui and Buzău valleys area in halomorphic soils, and in the Făgăraş Depression which is under the industrial polluting influence of chemical works. Among the causes for these differences is the uniformity or non-uniformity of the terrains, induced by land use and the existence or not of a handicap (polluting impact or halomorphic soils, for example). In general, there are no significant differences between the selenium mobility values and their grouping or scattering degree in the soil depth. A single exception stands out, namely in the Făgăraş Depression, where the selenium solubilization degree tends to increase with soil depth, as well as the scattering degree. In the Danube Delta diked areas Sireasa and Pardina very significant correlations have been computed, direct between the selenium solubilization degree and soil reaction and indirect with the humus, total nitrogen, mobile phosphorus and potassium contents. In the other areas the soils agrochemical properties don’t seem to influence selenium solubilization, not directly anyway.

The paper presents the results of an experiment carried out in controlled conditions, regarding triticale plants growth on a nutritive layer consisting of a mixture of red mud, acid rock and compost, in different proportions. The analytical results highlighted the strongly alkaline reaction of the layer, high organic carbon, mobile phosphorus and potassium contents and low nitrogen contents. The layer has a high salinity and sodium salts are predominant. The total microelements and heavy metals contents are generally acceptable. The triticale plants grew in these conditions up to 10-15 cm height, when the experiment was stopped. The plants accumulated normal nitrogen, calcium and magnesium quantities, low potassium ones, high phosphorus and very high sodium contents. The metallic microelements (copper, iron, manganese, zinc) accumulated at relatively normal levels, but the heavy metals (cadmium, cobalt, chromium, nickel, lead) concentrated up to values several tens of times higher than the normal contents. Introducing the obtained vegetal mass in the nutritive layer will contribute to enhancing its fertility for the next vegetation cycles.

Researches have been carried out with medicinal herbs in the frame of a National project financed by CNCSIS through the Partnership Program. Ecologic and conventional technologies were applied. The project aimed to implement a standardization system of the vegetal raw materials which can be used in the cosmetic industry. Sage, basilicum, and savory were subject of the experiments, at Jucu, Cluj County, Ungureni – Butimanu, Dâmboviţa County, and Secuieni, Neamţ County. The dominant soils in these areas are Fluvisols and Haplic Chernozems in the Jucu area, Chromic Luvisol in the Ungureni – Butimanu area, and Calcic Chernozem in the Secuieni area. The agrochemical analysis of the soils from the experimental fields highlighted soil fertility properties conservation both under ecologic and conventional growing technologies.

Selenium contents were determined in the A horizon of the Salsodisols (Solonchaks and Solonetz)placed along the Călmăţui and Buzău Valleys. The total selenium content oscillated between 480 and 1140g·kg-1, with an average value of 800 g·kg-1. This value is 2.1 times higher than the selenium total content inthe upper horizon of the World’s non-halomorphic soils. It is also higher than the selenium total content in the upper horizon of the soils from Dobrogea and the South-Eastern Romanian Plain, 5.6 respectively 3.4 times. The mobile selenium content, soluble in the EDTA-CH3COONH4 solution at pH = 7, ranged in the 13-25 g·kg-1 interval, with an average value of 18 g·kg-1, 4 times higher than the mobile selenium contents of the Dobrogea soils upper horizon and 1.2 times higher than the ones in the South-Eastern part of the Romanian Plain. Between the selenium total contents and some Salsodisols physical and chemical properties proportionality relations were established, statistically ensured. Most of these soils’ selenium content is to be found as calcium, sodium, or magnesium (secondary) selenates. The presence of the same cations’ selenites is not excluded.

More than 20 years later, a new research on heavy metals (cadmium, cobalt, chromium, copper) contents in the soil cover of the Pantelimon – Brăneşti area located East of the Bucharest Municipality and exposed for several decades to the influence of industrial emissions from two non-ferrous metallurgy plants is presented. A 5,912.72 ha area was investigated, 544 samples taken by geometric horizons (0-20; 20-40; 40-60 cm) from 215 points have been analyzed.The dominant soils are: Preluvosols, Chernozems, Phaeozems. The analytical data showed that all the heavy metals contents are below the maximum allowable limits and of the alarm thresholds. Higher cadmium and copper concentrations have been registered in the 40-60 cm layer and higher chromium and copper concentrations in the 0-20 cm layer. Cadmium and cobalt distributions are non-central, with a right asymmetry, and the chromium and copper ones are slightly symmetric. The surface distribution of the heavy metals shows the presence of some high contents areas distributed insularly, with a higher frequency around the industrial units. The geochemical abundance indexes are higher than 1 for cadmium and lower for cobalt, chromium, and copper, and the pedo-geochemical abundance indexes are lower than 1 only for chromium.