Fenton's pre-treatment of mature landfill leachate

The aim of this study was to check the effectiveness of the Fenton's reagent (Fe2+ + H2O2 + H+) for the pre-treatment of a municipal landfill leachate with the objective of improving its overall biodegradability, evaluated in terms of BOD5/COD ratio, up to a value compatible with biological treatment. The leachate came from a municipal sanitary landfill located in southern Italy and the average values of its main parameters were: pH=8.2; COD=10,540 mgl(-1); BOD5=2,300 mgl(-1); TOC=3,900 mgl(-1); NH4-N=5210 mgl(-1); conductivity=45,350 microScm(-1); alkalinity=21,470 mgl(-1) CaCO3. The effect of initial pH value on the pre-treatment effectiveness was evaluated by titrating the amount of acidic by-products formed. The extent of leachate oxidation was monitored and controlled by both pH and redox potential measurements. The best operational conditions for achieving the desired goal (i.e., BOD5/COD> or =0.5) resulted: Fe2+=275 mgl(-1); H2O2=3,300 mgl(-1); initial pH=3; reaction time=2 h. At the end of the Fenton's pre-treatment, in order to permit a subsequent biological treatment, residual ferric ions were removed increasing the pH up to 8.5 by adding 3 gl(-1) of Ca(OH)2 and 3 mgl(-1) of a cationic polyelectrolyte, the latter as an aid to coagulation. This final step also resulted in a further modest removal of residual COD due to co-precipitation phenomena.     

Mediterranean cyclones and windstorms in a changing climate

Changes in the frequency and intensity of cyclones and associated windstorms affecting the Mediterranean region simulated under enhanced Greenhouse Gas forcing conditions are investigated. The analysis is based on 7 climate model integrations performed with two coupled global models (ECHAM5 MPIOM and INGV CMCC), comparing the end of the twentieth century and at least the first half of the twenty-first century. As one of the models has a considerably enhanced resolution of the atmosphere and the ocean, it is also investigated whether the climate change signals are influenced by the model resolution. While the higher resolved simulation is closer to reanalysis climatology, both in terms of cyclones and windstorm distributions, there is no evidence for an influence of the resolution on the sign of the climate change signal. All model simulations show a reduction in the total number of cyclones crossing the Mediterranean region under climate change conditions. Exceptions are Morocco and the Levant region, where the models predict an increase in the number of cyclones. The reduction is especially strong for intense cyclones in terms of their Laplacian of pressure. The influence of the simulated positive shift in the NAO Index on the cyclone decrease is restricted to the Western Mediterranean region, where it explains 10–50 % of the simulated trend, depending on the individual simulation. With respect to windstorms, decreases are simulated over most of the Mediterranean basin. This overall reduction is due to a decrease in the number of events associated with local cyclones, while the number of events associated with cyclones outside of the Mediterranean region slightly increases. These systems are, however, less intense in terms of their integrated severity over the Mediterranean area, as they mostly affect the fringes of the region. In spite of the general reduction in total numbers, several cyclones and windstorms of intensity unknown under current climate conditions are identified for the scenario simulations. For these events, no common trend exists in the individual simulations. Thus, they may rather be attributed to long-term (e.g. decadal) variability than to the Greenhouse Gas forcing. Nevertheless, the result indicates that high-impact weather systems will remain an important risk in the Mediterranean Basin.     

3,4-Dimethylpyrazol phosphate effect on nitrous oxide, nitric oxide, ammonia, and carbon dioxide emissions from grasslands

Intensively managed grasslands are potentially a large source of NH3, N2O, and NO emissions because of the large input of nitrogen (N) in fertilizers. Addition of nitrification inhibitors (NI) to fertilizers maintains soil N in ammonium form. Consequently, N2O and NO losses are less likely to occur and the potential for N utilization is increased, and NH3 volatilization may be increased. In the present study, we evaluated the effectiveness of the nitrification inhibitor 3,4-dimethylpyrazol phosphate (DMPP) on NH3, N2O, NO, and CO2 emissions following the application of 97 kg N ha(-1) as ammonium sulfate nitrate (ASN) and 97 kg NH4+ -N ha(-1) as cattle slurry to a mixed clover-ryegrass sward in the Basque Country (northern Spain). After slurry application, 16.0 and 0.7% of the NH4+ -N applied was lost in the form of N2O and NO, respectively. The application of DMPP induced a decrease of 29 and 25% in N2O and NO emissions, respectively. After ASN application 4.6 and 2.8% of the N applied was lost as N2O and NO, respectively. The application of DMPP with ASN (as ENTEC 26; COMPO, Münster, Germany) unexpectedly did not significantly reduce N2O emissions, but induced a decrease of 44% in NO emissions. The amount of NH4+ -N lost in the form of NH3 following slurry and slurry + DMPP applications was 7.8 and 11.0%, respectively, the increase induced by DMPP not being statistically significant. Levels of CO2 emissions were unaffected in all cases by the use of DMPP. We conclude that DMPP is an efficient nitrification inhibitor to be used to reduce N2O and NO emissions from grasslands.     

Only carapace or the entire cephalothorax: which is best to obtain chitosan from shrimp fishery waste?

Journal of Material Cycles and Waste Management - The polysaccharide chitin (CHIT), extracted mainly from exoskeletons of crustaceans, can be obtained from shrimp fishery waste. It is the source of...     

Fate of pesticides in tropical soils of Brazil under field conditions

The potential of pesticides for nonpoint ground water pollution depends on their dissipation and leaching behavior in soils. We investigated the fate of 10 pesticides in two tropical soils of contrasting texture in the Brazilian Cerrado region near Cuiabá during an 80-d period, employing topsoil dissipation studies, soil core analyses, and lysimeter experiments. Dissipation of pesticides was rapid, with field half-lives ranging from 0.8 to 20 d in Ustox and 0.6 to 11.8 d in Psamments soils. Soil core analyses showed progressive leaching of polar pesticides in Psamments, whereas in Ustox pesticides were rapidly transported to 40 cm soil depth regardless of their sorption properties, suggesting that leaching was caused by preferential flow. In lysimeter experiments (35 cm soil depth), cumulative leaching was generally low, with < or = 0.02% and < or = 0.19% of the applied amounts leached in Ustox and Psamments, respectively. In both soils, all pesticides but the pyrethroids were detected in percolate at 35 cm soil depth within the first 6 d after application. Cumulative efflux and mean concentrations of pesticides in percolate were dosely correlated with their Groundwater Ubiquity Score (GUS). The presence of alachlor (2-chloro-2', 6'-diethyl-N-methoxymethylacetanilide), atrazine (2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine), metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide], simazine [2-chloro-4,6-bis(ethylamino)-1,3,5-triazine], and trifluralin (2,6-dinitro-N,N-dipropyl-4-trifluoromethylaniline) throughout the soil profile and in percolate of wick lysimeters at 95 cm soil depth indicated that a nonpoint pollution of ground water resources in tropical Brazil cannot be ruled out for these substances.     

Pesticides in surface water,sediment, and rainfall of the northeastern Pantanal basin,Brazil

Within the last 25 years an intensive agriculture has developed in the highland regions of Mato Grosso state (Brazil), which involves frequent pesticide use in highly mechanized cash-crop cultures. To provide information on pesticide distribution and dynamics in the northeastern Pantanal basin (located in southern Mato Grosso), we monitored 29 pesticides and 3 metabolites in surface water, sediment, and rainwater of the study area during the main application season. In environmental samples, 19 pesticides and 3 metabolites were detected in measurable quantities, resulting in at least one pesticide detection in 68% of surface water samples (n = 139), 62% of sediment samples (n = 26), and 87% of rainwater samples (n = 91). Surface water samples were most frequently contaminated by endosulfan compounds (alpha-, beta-, -sulfate), ametryn, metolachlor, and metribuzin, although in low (< 0.1 microgram L-1) concentrations. Sediment samples exhibited concentrations up to 4.5 micrograms kg-1 of p,p'-DDT, p,p'-DDE, endosulfan-sulfate, beta-endosulfan, and ametryn. In contrast, rainwater was polluted with substantial amounts of endosulfan, alachlor, metolachlor, trifluralin, monocrotofos, and profenofos (maximum concentrations = 0.3 to 2.3 micrograms L-1) in the highlands. Lowland rainwater samples taken 75 km from the next application area contained 5- to 10-fold lower mean pesticide concentration than in the highlands. Cumulative deposition rates of the pesticide sum within the study period ranged from 423 micrograms m-2 in the highlands to 14 micrograms m-2 in the lowlands. The atmospheric input of pesticides to ecosystems seemed to be of higher relevance in the tropical study area than known from temperate regions.