Effects of management intensity on land snails in Swiss nutrient-poor pastures

The influence of management intensity on the richness, abundance and composition of land snail species was examined in 21 calcareous, nutrient-poor cattle pastures in the northwestern Jura mountains, Switzerland. Grazing intensity was positively correlated with the extent of fertilization of the pastures. Pastures without fertilizer application and with low grazing intensity harboured more snail species and more threatened snails than pastures with annual addition of manure or pastures with manure and nitrogen fertilizer and higher grazing intensity. Fewer snail individuals, open-land species and open-land individuals were found on pastures with high than on pastures with low management intensity. To preserve the threatened snail species in dry, nutrient-poor grasslands, a network of pastures should be managed without fertilization and grazing intensity should not exceed 180 LU ha⁻¹ d (product of livestock units per hectare and grazing days).     

Effect of substrate Henry's constant on biofilter performance

Butanol, ether, toluene, and hexane, which have Henry's constants ranging from 0.0005 to 53, were used to investigate the effects of substrate solubility or availability on the removal of volatile organic compounds (VOCs) in trickle-bed biofilters. Results from this study suggest that, although removal of a VOC generally increases with a decrease in its Henry's constant, an optimal Henry's constant range for biofiltration may exist. For the treatment of VOCs with high Henry's constant values, such as hexane and toluene, the transfer of VOCs between the vapor and liquid phases or between the vapor phase and the biofilm is a rate-determining step. However, oxygen (O2) transfer may become a rate-limiting step in treating VOCs with low Henry's constants, such as butanol, especially at high organic loadings. The results demonstrated that in a gas-phase aerobic biofilter, nitrate can serve both as a growth-controlling nutrient and as an electron acceptor in a biofilm for the respiration of VOCs with low Henry's constants. Microbial communities within the biofilters were examined using denaturing gradient gel electrophoresis to provide a more complete picture of the effect of O2 limitation and denitrification on biofilter performance.     

Pyrene degradation by yeasts and filamentous fungi

The saprotrophic soil fungi Fusarium solani (Mart.) Sacc., Cylindrocarpon didymum (Hartig) Wollenw, Penicillium variabile Sopp. and the yeasts Rhodotorula glutinis (Fresenius) Harrison and Rhodotorula minuta (Saito) Harrison were cultured in mineral medium with pyrene. The remaining pyrene concentrations were periodically determined during 20 incubation days, using HPLC. To assess the metabolism of pyrene degradation we added 0.1 microCi of [4,5,9,10] 14C-pyrene to each fungi culture and measured the radioactivity in the volatile organic substances, extractable, aqueous phase, biomass and 14CO2 fractions. The assays demonstrated that F. solani and R. glutinis metabolized pyrene as a sole source of carbon. Differences in their activities at the beginning of the cultures disappeared by the end of the experiment, when 32 and 37% of the original pyrene concentration was detected, for the soil fungi and yeasts, respectively. Among the filamentous fungi, F. solani was highly active and oxidized pyrene; moreover, small but significant degradation rates were observed in C. didymum and P. variahile cultures. An increase in the 14CO2 evolution was observed at the 17th day with cosubstrate. R. glutinis and R. minuta cultures showed similar ability to biotransform pyrene, and that 35% of the initial concentration was consumed at the end of the assay. The same results were obtained in the experiments with or without glucose as cosubstrate.     

Stress biomarkers and alkali-labile phosphate level in mussels (Mytilus galloprovincialis) collected in the urban area of Venice (Venice Lagoon, Italy)

In this study, a spatial and temporal survey at three sites located in the "canals" of the Venice historic centre (Italy) and at a reference site was undertaken to evaluate stress effects on mussels sampled in the Venice urban area, where raw sewage is discharged without treatment directly into the water. A battery of biomarkers (metallothionein, micronuclei, condition index and survival in air) was used to evaluate the stress condition of the animals. At the same time the alkali-labile phosphate assay (ALP) was performed in mussel' hemolymph with the aim to find an estrogenic effect biomarker in this mussel species. Biomarker results showed an impairment of the general health condition in the mussels coming from the urban area, in agreement with the chemical analysis. Significantly higher level of the ALP was found in male mussels sampled in April in the urban area, in comparison with the ones from the reference site (P<0.001). Finally, the PCA proved an easy and useful tool to summarize the obtained results, also able to classify the data to indicate a pollution gradient in the Venice urban area.     

Methane oxidation and attenuation of sulphur compounds in landfill top cover systems: Lab-scale tests

In this study,a top cover system is investigated as a control for emissions during the aftercare of new landfills and for old landfills where biogas energy production might not be profitable.Different materials were studied as landfill cover system in lab-scale columns:mechanical–biological pretreated municipal solid waste(MBP);mechanical–biological pretreated biowaste(PB);fine(PBS_f)and coarse(PBS_c)mechanical–biological pretreated mixtures of biowaste and sewage sludge,and natural soil(NS).The effectiveness of these materials in removing methane and sulphur compounds from a gas stream was tested,even coupled with activated carbon membranes.Concentrations of CO_2,CH_4,O_2,N_2,H_2S and mercaptans were analysed at different depths along the columns.Methane degradation was assessed using mass balance and the results were expressed in terms of methane oxidation rate(MOR).The highest maximum and mean MOR were observed for MBP(17.2 g CH_4/m~2/hr and 10.3 g CH_4/m~2/hr,respectively).Similar values were obtained with PB and PBS_c.The lowest values of MOR were obtained for NS(6.7 g CH_4/m~2/hr)and PBS_f(3.6 g CH_4/m~2/hr),which may be due to their low organic content and void index,respectively.Activated membranes with high load capacity did not seem to have an influence on the methane oxidation process:MBP coupled with 220 g/m~2and 360 g/m~2membranes gave maximum MOR of 16.5 g CH_4/m~2/hr and 17.4 g CH_4/m~2/hr,respectively.Activated carbon membranes proved to be very effective on H_2S adsorption.Furthermore,carbonyl sulphide,ethyl mercaptan and isopropyl mercaptan seemed to be easily absorbed by the filling materials.