Neural network modelling for the analysis of forcings/temperatures relationships at different scales in the climate system

A fully non-linear analysis of forcing influences on temperatures is performed in the climate system by means of neural network modelling. Two case studies are investigated, in order to establish the main factors that drove the temperature behaviour at both global and regional scales in the last 140 years. In particular, our neural network model shows the ability to catch non-linear relationships among these variables and to reconstruct temperature records with a high degree of accuracy. In this framework, we clearly show the need of including anthropogenic inputs for explaining the temperature behaviour at global scale and recognise the role of El Niño southern oscillation for catching the inter-annual variability of temperature data. Furthermore, we analyse the relative influence of global forcing and a regional circulation pattern in determining the winter temperatures in Central England, showing that the North Atlantic oscillation represents the driven element in this case study. Our modelling activity and results can be very useful for simple assessments of relationships in the complex climate system and for identifying the fundamental elements leading to a successful downscaling of atmosphere–ocean general circulation models.     

Alkylphenol polyethoxylate removal in a pilot-scale reed bed and phenotypic characterization of the aerobic heterotrophic community.

The removal of the non-ionic surfactant Triton X-100, dosed at 30 and 300 mg/L in a pilot-scale subsurface horizontal flow reed bed, and the aerobic heterotrophic cultivable community associated with the roots and with the substrate gravel in both absence and presence of Triton X-100 were investigated. t-Octylphenol (OP) and its mono-, di- and tri-ethoxyl derivatives, among others, were found in the outlet. A mass balance allowed us to calculate that approximately 40% of the Triton X-100 metabolites OP and octylphenol polyethoxylate derivatives flowed out of the reed bed during the dosage and postdosage experiments. More aerobic heterotrophic microorganisms adhered to the roots than to the gravel. The appearance of new strains (Aeromonas, Flavobacterium, and Aquaspirillum) and the increased presence of others (Pseudomonas) during the dosage of Triton may be linked to the capacity of these bacteria to adapt to the presence of the surfactant or to use it as a nourishment.     

Estimation of road vehicle exhaust emissions from 1992 to 2010 and comparison with air quality measurements in Genoa,Italy

An investigation into road transport exhaust emissions in the Genoa urban area was performed by comparing the quantities of carbon monoxide (CO), nitrogen oxides (NO_x), nitrogen dioxide (NO₂) and particulate matter (PM) emitted by different vehicle categories with air quality measurements referred to the same pollutants. Exhaust emissions were evaluated by applying the PROGRESS (computer PROGramme for Road vehicle EmiSSions evaluation) code, developed by the Internal Combustion Engines Group of the University of Genoa, to eight different years (from 1992 to 2010), considering spark ignition and Diesel passenger cars and light duty vehicles, heavy duty vehicles and buses, motorcycles and mopeds. Changes in terms of vehicles number, mileage and total emissions are presented together with relative distributions among the various vehicle categories. By comparing 1992 and 2010 data, calculated trends show a 7% increase in the number of vehicles, with total mileage growing at a faster rate (approx. 22%); total emissions decrease considerably, by approximately 50% for NO_x and PM, 70% for HC and 80% for CO, due to improvements in engines and fuels forced by the stricter European legislation and the fleet renewal, while primary NO₂ emission will be very close to 1992 level, after a decrease of about 18% in 2000.Air quality was analysed by selecting traffic and background measuring stations from the monitoring network managed by the Environmental Department of the Province of Genoa: average annual concentrations of considered pollutants from 1994 to 2007 were calculated in order to obtain the relative historical trends and compare them with European public health limits and with road vehicle emissions. Though an important reduction in pollutant concentrations has been achieved as a consequence of cleaner vehicles, some difficulties in complying with present and/or future NO₂ and PM₁₀ limits are also apparent, thus requiring suitable measures to be taken by the local authorities.     

Electrostatic Precipitation Tests with Fuel Oil Ash

The main characteristics of the electrostatic collection of fuel oil ash has been investigated at a pilot precipitator installed in a laboratory rig. The relationship between collection efficiency, dust concentration and air velocity is studied and the influence of the spacing between the collection plates on both efficiency and effective migration velocity is discussed. Emphasis is put on the high degrees of efficiency attainable under suitable operating conditions.     

Recovery of different waste vegetable oils for biodiesel production: A pilot experience in Bahia State,Brazil

In Brazil, and mainly in the State of Bahia, crude vegetable oils are widely used in the preparation of food. Street stalls, restaurants and canteens make a great use of palm oil and soybean oil. There is also some use of castor oil, which is widely cultivated in the Sertão Region (within the State of Bahia), and widely applied in industry. This massive use in food preparation leads to a huge amount of waste oil of different types, which needs either to be properly disposed of, or recovered. At the Laboratorio Energia e Gas-LEN (Energy & Gas lab.) of the Universidade Federal da Bahia, a cycle of experiments were carried out to evaluate the recovery of waste oils for biodiesel production. The experiences were carried out on a laboratory scale and, in a semi-industrial pilot plant using waste oils of different qualities. In the transesterification process, applied waste vegetable oils were reacted with methanol with the support of a basic catalyst, such as NaOH or KOH. The conversion rate settled at between 81% and 85% (in weight). The most suitable molar ratio of waste oils to alcohol was 1:6, and the amount of catalyst required was 0.5% (of the weight of the incoming oil), in the case of NaOH, and 1%, in case of KOH.The quality of the biodiesel produced was tested to determine the final product quality. The parameters analyzed were the acid value, kinematic viscosity, monoglycerides, diglycerides, triglycerides, free glycerine, total glycerine, clearness; the conversion yield of the process was also evaluated.     

A dynamic optimization model for solid waste recycling

Recycling is an important part of waste management (that includes different kinds of issues: environmental, technological, economic, legislative, social, etc.). Differently from many works in literature, this paper is focused on recycling management and on the dynamic optimization of materials collection. The developed dynamic decision model is characterized by state variables, corresponding to the quantity of waste in each bin per each day, and control variables determining the quantity of material that is collected in the area each day and the routes for collecting vehicles. The objective function minimizes the sum of costs minus benefits. The developed decision model is integrated in a GIS-based Decision Support System (DSS). A case study related to the Cogoleto municipality is presented to show the effectiveness of the proposed model. From optimal results, it has been found that the net benefits of the optimized collection are about 2.5 times greater than the estimated current policy.     

Cancer incidence in people with residential exposure to a municipal waste incinerator: An ecological study in Modena (Italy), 1991–2005

We conducted a retrospective ecological study to assess cancer incidence during the period 1991–2005 in proximity of a municipal waste incinerator (MWI) in Modena (Italy). We identified three bands of increasing distance from the MWI, up to a radius of 5 km and used the residence as surrogate marker of the exposure. Residential history for Modena’s population was reconstructed and residents were associated to the most appropriate census unit. Age-standardized incidence ratios (ASR) and standardized incidence ratios (SIR) were estimated for all cancers and selected sites. Variations in cancer incidence were investigated using space and space–time scan statistic. Deprivation index was taken into account as potential confounding factor. During the 15-year study period, 16,443 new cases of cancer were diagnosed among residents in Modena. The space–time clustering test identified three significant clusters but their shapes were not associable to the MWI exposition. The purely spatial analysis not showed statistically significant clusters. The SIR computed for all cancers and selected sites did not show any excess of risk in the area closest to the plant. Higher SIR for leukaemia was found in the second band from MWI (2–3.5 km) for females (SIR, age and DI adjusted: 1.35, 95%CI: 1.01–1.79) and for both sexes (SIR, age and DI adjusted: 1.28, 95%CI: 1.03–1.57), but not a spatial trend was observed, thus excluding a possible link with MWI. In conclusion, bearing in mind the intrinsic limits of the study, the results suggest that there is no detectable increase of cancer risk for people living in proximity to the Modena MWI.     

Heavy metal ion influence on the photosynthetic growth of Rhodobacter sphaeroides

The potential of purple non-sulphur bacteria for bioremediation was assessed by investigating the ability of Rhodobacter sphaeroides strain R26.1 to grow photosynthetically in heavy metal contaminated environments. Bacterial cultures were carried out in artificially polluted media, enriched with the transition metal ions Hg2+, Cu2+, Fe2+, Ni2+, Co2+, MoO4(2-), and CrO4(2-) in millimolar concentration range. For each investigated ion the effect on growth parameters was evaluated. The analysis of concentration-effect curves revealed a differentiated response, indicating that diverse mechanisms of tolerance and/or resistance are involved. Adaptation or selection procedures were not applied, leading to assess intrinsic abilities of coping with these contaminants. The microorganism proved to be highly tolerant to heavy metal exposure, especially towards Co2+, Fe2+ and MoO4(2-). In addition Ni2+ and Co2+ were found to decrease the cellular content of light harvesting complexes. A characteristic behavior was observed with mercuric ions, which produced a significant increase of the lag-phase.     

Multi-objective optimization of solid waste flows: environmentally sustainable strategies for municipalities

An approach to sustainable municipal solid waste (MSW) management is presented, with the aim of supporting the decision on the optimal flows of solid waste sent to landfill, recycling and different types of treatment plants, whose sizes are also decision variables. This problem is modeled with a non-linear, multi-objective formulation. Specifically, four objectives to be minimized have been taken into account, which are related to economic costs, unrecycled waste, sanitary landfill disposal and environmental impact (incinerator emissions). An interactive reference point procedure has been developed to support decision making; these methods are considered appropriate for multi-objective decision problems in environmental applications. In addition, interactive methods are generally preferred by decision makers as they can be directly involved in the various steps of the decision process. Some results deriving from the application of the proposed procedure are presented. The application of the procedure is exemplified by considering the interaction with two different decision makers who are assumed to be in charge of planning the MSW system in the municipality of Genova (Italy).     

Seasonal, spatial and inter-annual variations of trace metals in mussels from the Adriatic sea: a regional gradient for arsenic and implications for monitoring the impact of off-shore activities

Mussels are widely used as bioindicator organisms for monitoring chemical pollutants including trace metals. These elements are natural constituents in the marine environment and their basal concentrations in the organisms can be influenced by several environmental and biological factors. The aim of this work was to extend our knowledge on the natural variability of trace metals in mussels tissues, focusing on seasonal and inter-annual fluctuations in a coastal reference site of the Adriatic coast (Portonovo); a total of 39 samplings were performed during 5 years, providing an extended data-set for tissue levels of As, Ba, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, V and Zn. Concentrations of trace metals in mussels tissues revealed marked seasonal fluctuations with significant differences between various sampling years. Such fluctuations appeared mostly related to phytoplanctonic blooms and especially to reproductive cycle which exhibited a certain inter-annual shift of the gametogenesis period. Lower concentrations were measured in summer months for the majority of elements while a different seasonal cycle was observed for arsenic, not correlated with gonadic development, neither with other elements. Chemical speciation of arsenic was characterized to distinguish compounds of natural origin from those potentially reflecting an anthropogenic impact. Arsenobetaine and arsenocholine were always the predominant forms (up to 85% of total arsenic), while a significant increase of dimethylarsine and trimethylarsine oxide in spring (24% of total arsenic) might reflect the effect of phytoplanctonic bloom on both geochemistry and trophic transfer of this element. A significant inter-annual variability was observed for both the seasonal cycle and the range of values measured for all the elements, with particularly marked differences for arsenic, ranging from less than 10 to more than 40 microg/g in summer periods of different years. Data obtained on reference mussels were used to assess the impact of 41 off-shore platforms distributed along 5 nautical districts in the Northern and Central Adriatic Sea. Organisms sampled on these structures from 2001 to 2005 exhibited a certain enrichment of cadmium and zinc, probably associated to the use of anodic electrodes. Marked annual and geographical variations were measured for concentrations of arsenic in mussels of different platforms. However, the comparison with results of Portonovo, allowed to exclude the anthropogenic impact of exploitation activities and revealed a natural regional gradient of arsenic levels in mussels tissues associated to the changing influence of the Po river runoff on seawater salinity. In particular the higher concentrations measured in organisms sampled from platforms in the Central compared to Northern Adriatic confirmed a significant relationship between salinity and arsenic bioaccumulation, consistent with a role of arsenobetaine as an acquired osmolyte for mussels. The overall results confirmed the importance of natural variability when assessing the potential impact of anthropogenic activities.