Raphael Bragança Alves Fernandes

Zn(II) adsorption from synthetic solution and kaolin wastewater onto vermicompost

The adsorption of Zn(II) from both synthetic solution and kaolin industry wastewater by cattle manure vermicompost was studied. The adsorption process was dependent on the various operating variables, viz., solution pH, particle size of the vermicompost, mass of vermicompost/volume of the Zn(II) solution ratio, contact time and temperature. The optimum conditions for Zn adsorption were pH 6.0, particle size of < or = 250 microm, 1 g per 10 mL adsorbent dose, contact time of 4h and temperature of 25 degrees C. Langmuir and Freundlich adsorption isotherms fit well in the experimental data and their constants were evaluated, with R(2) values from 0.95 to 0.99. In synthetic solution, the maximum adsorption capacity of the vermicompost for Zn(2+) ions was 20.48 mg g(-1) at 25 degrees C when the vermicompost dose was 1 g 10 mL(-1) and the initial adjusted pH was 2. The batch adsorption studies of Zn(II) on vermicompost using kaolin wastewater have shown the maximum adsorption capacity was 2.49 mg g(-1) at pH 2 (natural pH of the wastewater). The small values of the constant related to the energy of adsorption (from 0.07 to 0.163 L mg(-1)) indicated that Zn(2+) ions were binded strongly to vermicompost. The values of the separation factor, R(L), which has been used to predict affinity between adsorbate and adsorbent were between 0 and 1, indicating that sorption was very favorable for Zn(II) in synthetic solution and kaolin wastewater. The thermodynamic parameter, the Gibbs free energy, was calculated for each system and the negative values obtained confirm that the adsorption processes are spontaneous. The DeltaG degrees values were -19.656 kJ mol(-1) and -16.849 kJ mol(-1) for Zn(II) adsorption on vermicompost in synthetic solution at pH 6 and 2, respectively, and -13.275 kJ mol(-1) in kaolin wastewater at pH 2.

Avaliação da concentração de metais pesados em áreas olerícolas no Estado de Minas Gerais

The objective of this study was to investigate the presence of heavy metals (Cd, Pb, Cu, Cr, Fe, Mn, Mo, Ni and Zn) in agricultural soils, irrigation waters and some vegetable crops in the State of Minas Gerais, Brazil. Samples were submitted to an acid digestion and the heavy metal contents were determined using an ICP-OES. The majority of soil samples presented low heavy metal content, and did not indicate accumulation of these elements in soil, with the exception of Cr and Cd, which presented contents justifying complementary analysis. However, for these elements, the DTPA extraction data were close to zero, indicating their low availability. In water samples the presence of Cd and Pb was not detected. Considering the maximum contents permitted by the Brazilian legislation, only a few samples were above the limits. In the vegetables samples, contents of Cd, Cr and Ni not even approached the critical limit, and the majority of the other elements barely exceeded the considered limit. In general, the data show that the soil, water and vegetables samples analyzed were not contaminated by heavy metals.

Aquatic contamination of the Turvo Limpo river basin at the Minas Gerais state, Brazil

The aquatic contamination from the discharge of untreated or inadequately treated municipal sewage, as well as from husbandry, agriculture, and the disposal of municipal garbage, metallic scraps and civil architecture residues in the neighborhood of the Turvo Limpo River basin was evaluated. The water-courses examined were the Sao Bartolomeu Stream, Turvo Sujo River, and Turvo Limpo River, located in the Minas Gerais State, Brazil. Water samples were collected at the river-side in the dry season (July, August, and September 2005) and analyzed for evaluation of pollutant inputs. The pH, dissolved oxygen (DO), biochemical oxygen demand (BOD), total phosphate, total ammonia nitrogen (NH3 + NH4+), nitrate and metal concentrations (Al, Ca, Cr, Cu, Fe, Mg, Ni, Pb, and Zn) in water samples were determined. The concentrations of these metals in the suspended solids were also determined. The suspended solids showed high concentrations of Zn (15,350 mg kg-1) and Pb (3,590 mg kg-1), while the stream water was enhanced with Al (1,480 µg L-1). The pH and the concentrations of BOD, total phosphate and total ammonia nitrogen in the water-courses were far from those established by the Brazilian Environmental Standards for Class 2 water. In all examined sites there was an increase in the nitrate concentration compared with that of a spring (site 1). The nitrate concentrations were below those of the total ammonia nitrogen, indicating that the nitrogen in the water-courses was mainly originated from recent sewage discharges, since did not occurred larger mineralization with the formation of nitrate ions.

Desenvolvimento de mudas de cedro-rosa em solo contaminado com cobre: tolerância e potencial para fins de fitoestabilização do solo

Agricultural, industrial and mining activities are the mainly factors related to soil contamination, as well the reuse of urban and/or animal residues. These activities can produce heavy metals accumulation in soils, which are potentially dangerous chemical elements to environmental quality and to well-being of living beings. Phytoremediation is a technology for rehabilitation of degraded areas which aims the soil decontamination. Forest species can immobilize and export to outside of the system larger amounts of chemical elements from contaminated soil, because they have high biomass production. The objective of this study was to evaluate the Cedrela fissilis development in contaminated soil by heavy metals. With this propose, seedlings were cultivated in greenhouse and in a contaminated soil by Cu (0, 60, 80, 100, 500 mg kg-1) for 105 days. After this period some soil and plant parameters were evaluated. Seedlings of C. fissilis presented crescent increments of dry matter until 100 mg kg-1 of Cu, with reduction of vegetal development in the high doses. In general, it was verified high partition of dry matter to root system than aerial part. Plant Cu contents were correlated with applied doses in the soil. The root bioconcentraction factor of C. fissilis indicates potential capacity of this tree specie to phytostabilization works in contaminated soils.

Metais pesados em amostras biológicas de bovinos

The aim of this research was to determine the heavy metals concentration in blood (Pb, Ni and Cd), serum (Cu and Zn), hair and milk (Pb, Ni, Cd, Cu and Zn) of cattle raised in industrial (with steel mill) and non-industrial areas in Minas Gerais, Brazil. The samples were collected during summer and winter, aiming to verify animals contamination related to environment and year season. The environment significantly influenced the concentration of Cu obtained on serum samples, with higher values for cattle from the industrialized area. The sampling time affected the concentration of Cu (serum), Zn (serum and milk), Pb (blood) and Cd (blood and hair), with higher values for summer, except for Cd measured on hair. Meaningful interactions (P<0.05) between environment and year season were identified for Cu (hair and milk), Zn (hair) and Ni (serum, hair and milk). The results obtained show that the presence of steel mills in a determined area does not mean, necessarily that higher concentration of heavy metals will be found in cattle biological matrices. The seasonality can influence the heavy metal concentration obtained from these matrices, fact that should be considered in environment monitoring programs.

Adsorption from Brazilian soils of Cu(II) and Cd(II) using cattle manure vermicompost

The potential of cattle manure vermicompost and Brazilian soils (whole soils and soils incubated with vermicompost) was assessed for adsorption of heavy metals such as Cu(II) and Cd(II) from aqueous solutions. Experimental data have been fitted to Langmuir and Freundlich isotherms to obtain the characteristic parameters of each model, with R 2 values from 0.89 to 0.99. Based on the maximum adsorption capacity obtained from the Langmuir isotherm the affinity of the studied metals for the vermicompost and soils have been established as Cu(II) > Cd(II). The values of the separation factor, R L, which has been used to predict affinity between adsorbate and adsorbent were between zero and 1, indicating that sorption was very favourable for Cu(II) and Cd(II) in synthetic solution. Addition of vermicompost to soils resulted in higher distribution coefficient, K d, as compared with whole soils. The thermodynamic parameter, the Gibbs energy changes, was calculated for each system and the negative values obtained confirm that the adsorption processes are spontaneous. The ΔG° values for the substrates were between −2.630±1.41 kJ mol−1 and −13.700±1.250 kJ mol−1. Adsorption tests from multimetal systems confirm the affinity order obtained in the individual metal tests. The adsorption capacity for Cu(II) measured in individual tests is not reduced by the presence of Cd(II). There is also desorption of Cu(II) and Cd(II) previously bound to vermicompost, whole soils and soils incubated with vermicompost by DTPA. The experiment indicates the importance of cattle manure vermicompost and oxisol amended with vermicompost in relation to Cu(II) and Cd(II) adsorption from aqueous solution.

CO2 and N2O emissions in a soil chronosequence at a glacier retreat zone in Maritime Antarctica

Studies of C cycle alterations are extremely important to identify changes due to climate change, especially in the polar ecosystem. The objectives of this study were to (i) examine patterns of soil CO2-C and N2O-N emissions, and (ii) evaluate the quantity and quality of soil organic matter across a glacier retreat chronosequence in the Maritime Antarctica. Field measurements were carried out during January and February 2010 (summer season) along a retreating zone of the White Eagle Glacier, at King George Island, Maritime Antarctica. Soil samples (0-10cm) were collected along a 500-m transect at regular intervals to determine changes in soil organic matter. Field CO2-C emission measurements and soil temperature were carried out at regular intervals. In addition, greenhouse gas production potentials were assessed through 100days laboratory incubations. Soils exposed for a longer time tended to have greater concentrations of soluble salts and possess sandier textures. Total organic C (3.59gkg(-1)), total N (2.31gkg(-1)) and labile C (1.83gkg(-1)) tended to be lower near the glacier front compared with sites away from it, which is correlated with decreasing degree of humification of the soil organic matter with exposure time. Soil CO2-C emissions tended to increase with distance from the glacier front. On average, the presence of vegetation increased CO2-C emissions by 440%, or the equivalent of 0.633g of CO2-C m(-2)h(-1). Results suggest that newly exposed landsurfaces undergo soil formation with increasing labile C input from vegetation, accompanied by increasing soil CO2-C emissions. Despite the importance of exposure time on CO2-C production and emissions, there was no similar trend in soil N2O-N production potentials as a function of glacial retreat. For N2O, instead, the maximum production occurred in sites with the first stages of vegetation growth.

Comparison of different methods for the determination of total organic carbon and humic substances in Brazilian soils

Aiming to compare three different methods for the determination of organic carbon (OC) in the soil and fractions of humic substances, seventeen Brazilian soil samples of different classes and textures were evaluated. Amounts of OC in the soil samples and the humic fractions were measured by the dichromate-oxidation method, with and without external heating in a digestion block at 130 °C for 30 min; by the loss-on-ignition method at 450 °C during 5 h and at 600 °C during 6 h; and by the dry combustion method. Dry combustion was used as reference in order to measure the efficiency of the other methods. Soil OC measured by the dichromate-oxidation method with external heating had the highest efficiency and the best results comparing to the reference method. When external heating was not used, the mean recovery efficiency dropped to 71%. The amount of OC was overestimated by the loss-on-ignition methods. Regression equations obtained between total OC contents of the reference method and those of the other methods showed relatively good adjustment, but all intercepts were different from zero (p < 0.01), which suggests that more accuracy can be obtained using not one single correction factor, but considering also the intercept. The Walkley-Black method underestimated the OC contents of the humic fractions, which was associated with the partial oxidation of the humin fraction. Better results were obtained when external heating was used. For the organic matter fractions, the OC in the humic and fulvic acid fractions can be determined without external heating if the reference method is not available, but the humin fraction requires the external heating.

Copper, nickel and zinc accumulations in lettuce grown in soil amended with contaminated cattle manure vermicompost after sequential cultivations

The Cu, Ni and Zn accumulations in leaves and roots of lettuce (Lactuca sativa L) grown in soil amended with natural and contaminated cattle manure vermicompost were evaluated. The vermicompost residues containing relatively high metal concentrations used in this work were obtained from a previous experiment, in which vermicompost was applied to removing metals from electroplating wastes. Sequential lettuce cultivations were conducted in pots containing the residual substrates from the first cultivation by adding metal-enriched vermicompost residues. In general, the Cu, Ni and Zn concentrations in leaves and roots of lettuce plants grown in vermicompost enriched with these metals were higher than in the treatment using the natural vermicompost. The metal concentrations in leaves from treatments with natural vermicompost were below the critical concentrations of toxicity to plants. However, the metal concentrations in leaves of the third cultivation in which metal-enriched vermicompost was applied were greater than the upper limit that causes plant toxicity, but no visual damage was observed in the plants. Treatment with Zn-enriched vermicompost resulted in toxicity symptoms, but plant damage did not result in the death of the plant. The chemical fractionation of Cu, Ni and Zn in residues from lettuce cultivation was evaluated by using a sequential extraction procedure and metal concentrations were increased in the different chemical fractions according to the increase of vermicompost dose.

Soil surface roughness under tillage practices and its consequences for water and sediment losses

The present study aims to determine the effects of soil management practices on soil surface roughness and the consequences of these phenomena on water and sediment losses. Laboratory experiment was conducted on a Chernozems clayey soil subjected to a sequence of two 30 min simulated rainfall of 50.8 mm h-1 and 114.3 mm h-1 and four soil management practices: contour tillage (CT), downhill tillage (DT), no-tillage simulated (NTs) and bare soil (BS). Soil surface roughness was evaluated using a laser distance meter. Results showed that the soil tillage in downhill or contour increased soil roughness by 2.90 and 2.76, respectively, reducing the water losses under low rain intensity by 12.8% and 6.4%. Soil surface roughness quickly changed after the onset of rain, and higher values of changes in soil roughness were observed for contour (22.73%) and downhill tillage (21.05%) managements. Soil coverage factor and the direction of tillage were the most important characteristics in contrast with soil surface roughness to reduce the sediment losses. No-tillage simulated (0.59 tha-1) and contour tillage (1.30 t ha-1) were the soil management practices with lower sediment losses compared to other managements studied. The principal theoretical implication of this study is that land use planning with agriculture, livestock must be designed to prevent the soil from being exposed, or if exposed, tillage in contour should be adopted. The input of litter on soil surface had an important role in reducing the sediment and water losses.