Evaluation of respiration in compost landfill biocovers intended for methane oxidation

A low-cost alternative approach to reduce landfill gas (LFG) emissions is to integrate compost into the landfill cover design in order to establish a biocover that is optimized for biological oxidation of methane (CH₄). A laboratory and field investigation was performed to quantify respiration in an experimental compost biocover in terms of oxygen (O₂) consumption and carbon dioxide (CO₂) production and emission rates. O₂ consumption and CO₂ production rates were measured in batch and column experiments containing compost sampled from a landfill biowindow at Fakse landfill in Denmark. Column gas concentration profiles were compared to field measurements. Column studies simulating compost respiration in the biowindow showed average CO₂ production and O₂ consumption rates of 107 ± 14 g m⁻² d⁻¹ and 63 ± 12 g m⁻² d⁻¹, respectively. Gas profiles from the columns showed elevated CO₂ concentrations throughout the compost layer, and CO₂ concentrations exceeded 20% at a depth of 40 cm below the surface of the biowindow. Overall, the results showed that respiration of compost material placed in biowindows might generate significant CO₂ emissions. In landfill compost covers, methanotrophs carrying out CH₄ oxidation will compete for O₂ with other aerobic microorganisms. If the compost is not mature, a significant portion of the O₂ diffusing into the compost layer will be consumed by non-methanotrophs, thereby limiting CH₄ oxidation. The results of this study however also suggest that the consumption of O₂ in the compost due to aerobic respiration might increase over time as a result of the accumulation of biomass in the compost after prolonged exposure to CH₄.     

Lichen colonization in the city of Turin (N Italy) based on current and historical data

The results of a study carried out to assess current environmental quality by the diversity of epiphytic lichens in the urban area of Turin (N Italy), and comparison with historical data spanning over a period of 200 years, are presented. Lichen assemblages over different time periods are related to changes in environmental conditions and the present situation is improving, as shown by increased numbers of both species and thalli in the city. Today, NO(x) and total suspended particles are the main air pollutants affecting lichen diversity.     

Distribution and Environmental Risk Assessment of Heavy Metal in Surface Sediments and Red Mullet (<Emphasis Type="Italic">Mullus barbatus</Emphasis>) from Algiers and BouIsmail Bay (Algeria)

BouIsmail (BIB) and Algiers (AB) are the most important bays in Algeria, where busy shipping activities and various industry complexes introduce different pollutants including heavy metals to the aquatic environment. The main goal of this study was to assess the contamination levels of heavy metals (Cd, Cr, Cu, Fe, Hg, Mn, Pb, Zn) in surface sediments and red mullet (Mullus barbatus) of the BIB and AB and to examine the possibility of the use of their enrichment factors (EFs) to track down the sources of metals (natural processes or human activity). The geoaccumulation index (I _geo) was calculated as a criterion to indicate the contamination level for each heavy metal. Moreover, geographical information systems based on spatial analysis methods (inverse distance weighting (IDW)) and statistical approaches (the principal component (PCA)) were performed to assess the spatial influences of multiple anthropogenic sources in different sampled areas. The results of both EF and I _geo revealed that the study area is exposed to various anthropogenic activities. The pollution load index (PLI) values of sediment samples in the different sites of Algiers and BIB ranged from 0.2 to 3.4 illustrating highly contaminated sediments. Significant bioaccumulation of Cd, Cu, Hg, Pb, and Zn (bioaccumulation factor >100%) were observed in muscle and liver of red mullet, suggesting potential health risks through consuming this fish species.