Evaluation of solvent extraction by ultrasound by using high performance liquid chromatography for the determination of polycyclic aromatic hydrocarbons in contaminated soils

A method using ultrasonication extraction for the determination of 17 polycyclic aromatic hydrocarbons (PAHs), selected by the USEPA and NIOSH as "consent decree" priority pollutants, in soil by High Performance Liquid Chromatography (HPLC) was studied. Separation and detection were completed in 20 min with a C18 columm, acetonitrile-water gradient elution and ultraviolet absorption and fluorescence detections. The detection limits, for a 10 µL of solution injection, were less than 9,917 ng/g in UV detection and less than 1,866 ng/g in fluorescence detection. Several organic solvents were tested for extraction of the 17 PAHs from soils. Acetone was the best solvent among the three solvents tested, and the order of the extraction efficiencies was: acetone>methanol>acetonitrile. Ultrasonication using acetone as solvent extraction was used to evaluate the biodegradation of those compounds in contaminated soil during a vermicomposting process

Influence of land use on the chemical and physical characteristics of sediments from the Brazilian Savannah

This study analyzed the chemical and physical characteristics of replicate sediment samples from water bodies distributed along a gradient of environmental degradation in an agricultural landscape. To assess the effect of agricultural land use (farming and livestock activity) in the Brazilian Savannah, the following sediment attributes were evaluated: pH, cation exchange capacity, organic matter (OM), total organic carbon, humic acids (HAs), and texture (granulometric analysis). In addition, the structure of the HAs was analyzed by infrared spectroscopy (FTIR), and the degree of OM transformation (dOMt) was determined by emission fluorescence. Compared with the ecological station (ES) (reference site), sediments from the livestock were highly altered, with a higher OM content (~100% difference) and a predominance of smaller size particles (35.00% clay and 45.20% silt). Samples with a higher OM content were related to a smaller dOMt; for example, the ES sediments contained 8.37% OM and had 37.07 dOMt, compared to 16.12% OM and a 25.98 dOMt in the livestock area sediments. In general, these findings provide detailed insight into how the conversion of a natural environment to an area of agricultural use (farming or livestock) amends the chemical and physical characteristics of its sediments

Determinação de zinco em solo utilizando colorimetria Determination of zinc in soil using colorimetry

<abstract language="eng">In terms of soil fertility, zinc is a micronutrient that is very important in the culture of soy, maize, rice and coffee, because it is a structural and functional component of a great number of enzymes. Therefore, diverse methods have been used to determine zinc in soil. In this work we use colorimetry as a methods of zinc determination in soil using two methodologies of sample digesting, H2SO4/H2O2 and HNO3/H2O2. In order to compare the results, atomic absorption spectrometry (AAS) was used. Results show that colorimetric methods can be used due to good sensitivity and reproducibility, since the zinc calibration curve showed good linearity. Comparing colorimetric methods with AAS we observed that the results were equivalent, as proven by the statistical values of the F and t of Student tests. Furthermore, both methods of soil digesting can be used, leading to a flexible methodology of low-cost for routine zinc analyses in soil

Distribuição de compostos organoclorados nas águas e sedimentos da bacia do rio Piracicaba/SP - Brasil

The great utilization of synthetic and persistent xenobiotic cumulative compounds is the main causes of the deterioration of aquatic ecosystems. The one of objective of this work was the determination of the organochlorine levels in the Piracicaba river basin, situated at the center of São Paulo state. Four PCBs congeners, PCP and HCB were determined by GC-ECD in two different matrices: water and sediments. The pattern of the compound distribution indicated a dominance of PCP, HCB and PCB-200. The results indicated contamination in the sampling points located in Campinas, Piracicaba, Santa Bárbara d'Oeste and Sumaré cities