Leaching of chromium from chromium contaminated soil: Speciation study and geochemical modeling

Distribution of chromium between soil and leachate was monitored. A natural process of percolating rainwater through the soil was simulated in the laboratory conditions and studied with column leaching extraction. Migration of chromium in the soil is conditioned by the level of chromium soil contamination, the soil organic matter content, and rainwater acidity. Chromium (III) and chromium(VI) were determined by spectrophotometric method with diphenilcarbazide in acidic media. Comparing the results of chromium speciation in leachate obtained by experimental model systems and geochemical modelling calculations using Visual MINTEQ model, a correlation was observed regarding the influence of the tested parameters. Leachate solutions showed that the concentration of Cr depended on the organic matter content. The influence of pH and soil organic matter content is in compliance after its definition through experimental and theoretical way. The computer model - Stockholm Humic Model used to evaluate the leaching results corresponded rather well with the measured values

Fluorine content in soils of Northern Pomoravlje

Soil sampling was carried out in the Velika Morava river valley, covering the area from Velika Plana to the mouth of Morava to the Danube. The composite soil samples, representing alluvial soils (22 samples), cambisols (14) and smonitzas (4), were taken from plough layers, based on a regular square grid with intervals set at 5x5 km, covering total area of 100,000 ha. The total and available fluorine contents were determined in the soils samples. The highest average amount of total fluorine was found for alluvial soils (391 mg kg-1), then for smonitzas (348 mg kg-1) and the lowest one for cambisols (285 mg kg-1). These amounts are within normal fluorine content for soils (150-400 mg kg-1), although the maximum found levels were even about 500 mg kg-1. The available fluorine content was very low (< 1 mg kg-1), being mostly less than 0.2 % from its total amount, so it could be concluded that there was no danger from fluorine accumulation in the plants. Statistically significant correlation coefficient between total and available fluorine contents was not obtained. The total and available fluorine contents have mostly been in the correlation (with positive sign) with soil pH and the content of mechanical fraction silt+clay. Significant correlation coefficients between total fluorine content and the content of some heavy metals (Cr, Ni, Co, Cu, As) were also found, which indicated their mutual geochemical origin

Eco-chemical characterisation of fluvisol of Velika Morava River valley (Serbia) based on the physico-chemical. parameters and distribution of heavy metals

Eco-chemical characteristics of the soil from the Velika Morava River valley were examined by analysis of 27 samples of agricultural soil of fluvisol type. The main physico-chemical parameters (pH, carbonate, humus, total nitrogen, available potassium and phosphorus contents), and total and available contents of heavy metals (Pb, Zn, Cu and Cd) were determined. The aim of this research was to have an insight into the current eco-chemical state in the examined agricultural region, by detection of the main substrates of heavy metals, as well as by analysis of their possible origin. In all the examined samples, total Zn, Cu and Cd contents, and in most of the examined samples, total contents of Pb, obtained by sequential extraction, were below maximum allowed concentrations (MAC) for agricultural soils. The increased content of total Pb (104.28-161.03 mg/kg) in some of the examined samples was probably caused by anthropogenic activity. Results of the sequential extraction, as, well as the extraction with diethylene triamine pentaacetic acid (DTPA), used for extraction of available metals, indicated the anthropogenic sources of Pb, Cu and Cd, whereas Zn was most often of geochemical, native origin. The obtained results were subject to correlation and factor analysis. Both methods confirmed the correlation between Zn and Cd, leading to the conclusion that a part of Zn was also of, anthropogenic origin. Factor analysis brought together total contents of Zn and Cd, and pH-value of the soil, and indicated the possibility of its easy mobilisation at slight changes in soil acidity

Biotransformation of nitric oxide in the cerebrospinal fluid of amyotrophic lateral sclerosis patients

Recent findings indicate that nitric oxide (NOcenter dot) over-production might be an important factor in the pathogenesis of sporadic amyotrophic lateral sclerosis (SALS). We measured significantly higher concentrations of uric acid and thiol group-containing molecules (R-SH groups) in the cerebrospinal fluid (CSF) from SALS patients compared to controls. The above factors, together with a slightly increased free iron concentration found in the CSF, favour conditions necessary for the formation of the dinitrosyl iron complex, capable of NOcenter dot bio-transformation. Thus, we performed ex vivo saturation of CSF ( from both SALS patients and controls) with NOcenter dot. A decrease in the level of R - SH was found. This was more pronounced in the CSF from SALS patients. In the CSF from SALS patients the production of nitrite and hydroxylamine was greater than that observed in the CSF from controls. Moreover, we also found increased Cu, Zn-SOD activity in the CSF from SALS patients ( when compared to control subjects) but no activity corresponding to Mn-SOD in any CSF samples. As Cu, Zn-SOD can react with nitroxyl forming NOcenter dot, the conditions for a closed, but continuous, loop of NOcenter dot biotransformation are present in the CSF of ALS patients.nul

Biotransformation of nitric oxide in the cerebrospinal fluid of amyotrophic lateral sclerosis patients

Recent findings indicate that nitric oxide (NOcenter dot) over-production might be an important factor in the pathogenesis of sporadic amyotrophic lateral sclerosis (SALS). We measured significantly higher concentrations of uric acid and thiol group-containing molecules (R-SH groups) in the cerebrospinal fluid (CSF) from SALS patients compared to controls. The above factors, together with a slightly increased free iron concentration found in the CSF, favour conditions necessary for the formation of the dinitrosyl iron complex, capable of NOcenter dot bio-transformation. Thus, we performed ex vivo saturation of CSF ( from both SALS patients and controls) with NOcenter dot. A decrease in the level of R - SH was found. This was more pronounced in the CSF from SALS patients. In the CSF from SALS patients the production of nitrite and hydroxylamine was greater than that observed in the CSF from controls. Moreover, we also found increased Cu, Zn-SOD activity in the CSF from SALS patients ( when compared to control subjects) but no activity corresponding to Mn-SOD in any CSF samples. As Cu, Zn-SOD can react with nitroxyl forming NOcenter dot, the conditions for a closed, but continuous, loop of NOcenter dot biotransformation are present in the CSF of ALS patients.nul