Volatile organic compounds produced during the aerobic biological processing of municipal solid waste in a pilot plant

The volatile organic carbon (VOC) and odours emitted during the aerobic biological processing of municipal solid waste (MSW) was studied in a pilot-scale reactor. VOCs were detected by different techniques on solid waste samples and the outlet air stream, before and after a biofilter. Organic compounds (alpha-pinene, beta-myrcene, D-limonene) were also measured in condensate water and leachate from the process. Results showed uniformity in the composition of the air in the solid waste samples, air sampled during the process and condensed water, indicating a matrix-derived origin of these compounds. Leachates, however, contained substances with a quite different molecular structure from the compounds identified in the gaseous fraction. Most of the substances in the gaseous effluent had a hydrocarbon-like structure, mainly terpenoids. The odour produced and detected through olfactometry agreed with GC-MS analyses. This was true above all for terpenes.     

Wind- and tide-induced currents in the Stagnone lagoon (Sicily)

The hydrodynamic circulation is analyzed in the coastal lagoon of Stagnone di Marsala, a natural reserve located in the north-western part of Sicily, using both experimental measurements and numerical simulations. Field measurements of velocities and water levels, carried out using an ultrasound sensor (3D), are used to validate the numerical model. A 3D finite-volume model is used to solve the Reynolds-averaged momentum and mass balance differential equations on a curvilinear structured grid, employing the k–e{\varepsilon} turbulence model for the Reynolds stresses. The numerical analysis allows to identify the relative contribution of the forces affecting the hydrodynamic circulation inside the lagoon. In the simulations only wind and tide forces are considered, neglecting the effects of water density changes. Two different conditions are considered. In the first both the wind stress over the free-surface and the tidal motion are imposed. In the second the wind action is neglected, to separately analyze the tide-induced circulation. The comparison between the two test cases highlights the fundamental role of the wind on the hydrodynamics of the Stagnone lagoon, producing a strong vertical recirculation pattern that is not observed when the flow is driven by tides only.     

Prey ecology and behaviour affect foraging strategies in the Great Cormorant

The fine link between a particular dive pattern and a specific prey item represents a challenging task in the analysis of marine predator–prey relationships. There is growing evidence that prey type affects diving seabirds’ foraging strategies, dive shapes and underwater activity costs. This study investigates whether a generalist diver, the Great Cormorant Phalacrocorax carbo, modifies the time budget allocated to prey-capture behaviour and breathing strategies (reactive vs. anticipatory) with respect to the prey type (pelagic vs. benthic). Video recordings of 91 Great Cormorants show how the ecology and behaviour of their main prey, Mullets (Mugilidae) and Flounders Platichthys flesus, affect dive/surface durations and the diving pattern. The demersal habit and the low mobility of Flounders leads to an easy access to prey with an anticipatory strategy. Moreover, the patchy distribution of this fish species increases prey-capture rates. Conversely, Mullets exploit the whole water column and are highly mobile, and this is reflected in the need of performing two sequential dives to capture a prey, both longer and likely more expensive, with a consequent switch of strategy from reactive in the searching phase to anticipatory breathing during prey-capture events. This study provides evidence that a generalist diver may switch between different foraging strategies, and it shows how each of them may be optimal under particular ecological conditions. These constraints influence the dynamics that operate within the marine food chains and have relevant implications in managing lagoon areas, including fish ponds.     

Vehicle-Induced Lead and Cadmium Contamination of Roadside Soil and Plants in Italy

Lead and cadmium concentrations in spontaneous vegetation and in soil sampled at various distances (0–208 m) from several motorways throughout Italy were measured. Lead and cadmium concentrations appear to be correlated to distance from the motorway and to traffic levels. A comparison with data from a remote and unpolluted site shows that foliar lead concentrations can be up to 40 times higher, and foliar cadmium concentrations up to 3 times higher. Plants behave differently in their accumulation of lead and cadmium; conifers present the highest levels. Also the various receptors and compartments of the roadside ecosystem differ in their accumulation of lead and cadmium; soil and bark have consistently higher concentrations, while the leaves and twigs of trees have consistently lower levels. the data recorded by ad hoc introduced bio-accumulating plants (Lolium multiflorum L.) are consistent with those of the spontaneous vegetation. the concentrations of both lead and cadmium in Lolium vary from June to November, following in part the fluctuation in traffic density.     

An individual-based analysis of the dynamics of two coexisting phytoplankton species in the mixed layer

In marine ecosystems ecological and environmental conditions continuously change, possibly supporting the wide range of phytoplankton species coexisting in aquatic environments. Phytoplankton communities are not homogeneously distributed in the water column due to the spatial and temporal variability of turbulent mixing and the concurrent biological response. In this paper an individual-based model (Lagrangian method) simulating the basic physiology of two coexisting phytoplankton species has been developed. The species, sharing the same availability of light and nutrient resource, are characterized by different photo-physiological parameters. The spatial and temporal evolution of turbulent mixing is simulated introducing vertical profiles of measured eddy diffusivity. Three case studies have been examined to analyze the role of environment–individual interactions in determining bloom conditions for both the selected species. The organisms experience recurrent fluctuations of light, temperature, and nutrient concentration gradients, due to the turbulent mixing in the water column, which have significant effects on the growth of the phytoplankton species. In all the numerical experiments, the temporal and spatial variability of different forcings do not support the prevalence of one species over the other over the time scale typical of a phytoplankton bloom.A well mixed water column favours the growth of both the populations while a variable mixing regime limits their growth reducing the photophysiological differences between the species.     

A biological and geochemical integrated approach to assess the environmental quality of a coastal lagoon (Ravenna, Italy)

The assessment of the environmental quality of coastal lagoons is rather difficult as their intrinsic high variability limits the power of analytical chemistry and ecotoxicological approaches. Aim of the present work was to integrate geochemical and biological data which were simultaneously collected from the Pialassa Baiona lagoon (Ravenna, Italy), and evaluate the usefulness of a biomonitoring strategy based on sentinel organisms and biomarkers. Geochemical analysis on suspended, surface, and subsurface sediments were performed at five different sites of the lagoon; moreover the heavy metal bioaccumulation and a battery of biomarkers was evaluated in Mytilus galloprovincialis transplanted in the same sites. Heavy metals appeared to be diffused throughout the lagoon reaching higher levels in the southernmost sites, and mainly concentrated in suspended sediments. Lysosome membrane stability, neutral lipid and lipofuscin accumulation, and metallothionein levels in mussels indicated the development of a stress syndrome in animals exposed to the polluted sites.     

What did Lotka really say? A critical reassessment of the “maximum power principle”

This paper presents a critical discussion of the so-called “maximum power principle”, often quoted in studies about the energy balance of living systems and also known in the emergy literature as “maximum em-power principle”. Several authors consider this principle highly relevant and some even proposed it as a “fourth law of thermodynamics”. A critical analysis of the original source, namely Alfred Lotka's 1921-22 papers, conducted both in an historical perspective (the connection between Lotka's writings and the ongoing debate at his time) and in a more modern context, leads to a more detailed and less biased assessment. It turns out that in spite of Lotka's very anticipatory and incredibly sharp vision of the possible interconnections between the second law of thermodynamics and evolutionism, doubts arise about the general applicability of his “maximum power principle”. From an accurate analysis of his writings, it can be concluded that: (a) Lotka explicitly and consistently addressed the “optimal use” of the flow of exergy (available energy), and therefore the quantity defined as “em-power” is an incorrect interpretation of Lotka's constrained maximum power principle; (b) “Lotka's principle” can be reformulated within Ziegler's “maximum entropy production” or Prigogine “minimum entropy generation” paradigm only under two different respective sets of rather stringent additional conditions which Lotka was probably already aware of but never explicitly stated.     

Diving costs and benefits during post-breeding movements of the Mediterranean shag in the North Adriatic Sea

From the 1980s, Mediterranean shags Phalacrocorax aristotelis desmarestii have become regular summer visitors in the Gulf of Trieste (N-E Italy), as post-breeding movements from Croatian breeding colonies. To characterize such a recent habit and to explore diving optimality models, we investigate foraging strategies and diving patterns at different depths, during breeding and post-breeding seasons. Behavioural data were cross-checked with the species’ diet. Shags foraged on and close to the sea bed, with a prevalent anticipatory breathing strategy. In the Gulf of Trieste, the shallow depths and low mobility of prey allowed shags to use just the oxygen of the respiratory tract, reducing the physiological stress for diving. In Croatia, dive costs increased with depth and prey mobility, resulting in a higher oxygen expenditure that involved also respiratory stores. Such ecological and physiological aspects characterize the Gulf of Trieste as an optimal area for feeding and restoring from the costs of breeding season incurred in Croatia and could be the basis of these post-breeding movements.     

Evaporites and continental drift

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