Speciation of inorganic arsenic in coastal seawater from Ionian and Tyrrhenian Seas (Sicily, Italy) using derivative anodic stripping chronopotentiometry

The purpose of this paper was to use derivative anodic stripping chronopotentiometry (dASCP) as a sensitive and accurate technique, to determine the concentrations of dissolved As (III) and As (V) in coastal seawater samples from the Straits of Messina, the Ionian and the Tyrrhenian seas, and to investigate the relationship between the anthropogenic activities on the coastal areas and the concentration of dissolved inorganic arsenic in seawaters. The obtained data indicated that As (V) was the most abundant species, with concentration ranging from 26.7 to 307 nM, whereas As (III) levels were lower than 48 nM in all the samples. In particular, As (III) and As (V) levels significantly decreased from high to low anthropogenic activities zones (p < 0.00001, ANOVA), with the reference samples, from a wildlife reserve, showing the lowest values. Furthermore it was observed that human activities influenced inorganic arsenic speciation, since the zones that received high human input presented the highest As(V)/As (III) ratio.     

Monitoring of Cr, Cu, Pb, V and Zn in polluted soils by laser induced breakdown spectroscopy (LIBS)

Laser Induced Breakdown Spectroscopy (LIBS) is a fast and multi-elemental analytical technique particularly suitable for the qualitative and quantitative analysis of heavy metals in solid samples, including environmental ones. Although LIBS is often recognised in the literature as a well-established analytical technique, results about quantitative analysis of elements in chemically complex matrices such as soils are quite contrasting. In this work, soil samples of various origins have been analyzed by LIBS and data compared to those obtained by Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES). The emission intensities of one selected line for each of the five analytes (i.e., Cr, Cu, Pb, V, and Zn) were normalized to the background signal, and plotted as a function of the concentration values previously determined by ICP-OES. Data showed a good linearity for all calibration lines drawn, and the correlation between ICP-OES and LIBS was confirmed by the satisfactory agreement obtained between the corresponding values. Consequently, LIBS method can be used at least for metal monitoring in soils. In this respect, a simple method for the estimation of the soil pollution degree by heavy metals, based on the determination of an anthropogenic index, was proposed and determined for Cr and Zn.     

Recycling of rubble from building demolition for low-shrinkage concretes

In this project concrete mixtures were prepared that were characterized by low ductility due to desiccation by using debris from building demolition, which after a suitable treatment was used as aggregate for partial replacement of natural aggregates. The recycled aggregate used came from a recycling plant, in which rubble from building demolition was selected, crushed, cleaned, sieved, and graded. Such aggregates are known to be more porous as indicated by the Saturated Surface Dry (SSD) moisture content. The recycled concrete used as aggregates were added to the concrete mixture in order to study their influence on the fresh and hardened concrete properties. They were added either after water pre-soaking or in dry condition, in order to evaluate the influence of moisture in aggregates on the performance of concrete containing recycled aggregate. In particular, the effect of internal curing, due to the use of such aggregates, was studied. Concrete behavior due to desiccation under dehydration was studied by means of both drying shrinkage test and German angle test, through which shrinkage under the restrained condition of early age concrete can be evaluated.     

Prediction of contaminant transport in fractured carbonate aquifer types: a case study of the Permian Magnesian Limestone Group (NE England,UK)

Viruses and bacteria which are characterized by finite lives in the subsurface are rapidly transported via fractures and cavities in fractured and karst aquifers. Here, we demonstrate how the coupling of a robust outcrop characterization and hydrogeophysical borehole testing is essential for prediction of contaminant velocities and hence wellhead protection areas. To show this, we use the dolostones of the Permian Magnesian Limestone aquifer in NE England, where we incorporated such information in a groundwater flow and particle tracking model. Within this aquifer, flow in relatively narrow (mechanical aperture of ~?10^?1–1 mm) fractures is coupled with that in pipe cavities (~?0.20-m diameter) following normal faults. Karstic cavities and narrow fractures are hydraulically very different. Thus, the solutional features are represented within the model by a pipe network (which accounts for turbulence) embedded within an equivalent porous medium representing Darcian flowing fractures. Incorporation of fault conduits in a groundwater model shows that they strongly influence particle tracking results. Despite this, away from faulted areas, the effective flow porosity of the equivalent porous medium remains a crucial parameter. Here, we recommend as most appropriate a relatively low value of effective porosity (of 2.8?×?10^?4) based on borehole hydrogeophysical testing. This contrasts with earlier studies using particle tracking analyses on analogous carbonate aquifers, which used much higher values of effective porosity, typically ~?10² times higher than our value, resulting in highly non-conservative estimates of aquifer vulnerability. Low values of effective flow porosities yield modelled flow velocities ranging from ~?100 up to ~?500 m/day in un-faulted areas. However, the high fracturing density and presence of karstic cavities yield modelled flow velocities up to ~?9000 m/day in fault zones. The combination of such flow velocities along particle traces results in 400-day particle traces up to 8-km length, implying the need for large well protection areas and high aquifer vulnerability to slowly degrading contaminants.

     

Temperature effects on fecundity,development and survival of the benthopelagic calanoid copepod, <Emphasis Type="Italic">Pseudocyclops xiphophorus</Emphasis>

The shallow-living, benthopelagic copepod species Pseudocyclops xiphophorus Wells (R Soc Edimburg 67:1967), collected over a yearly cycle from the fouling material in the brackish water Lake Faro (North-eastern Sicily), showed marked seasonal fluctuations in population abundances, with maximum numbers recorded in autumn. Highest in situ egg production rates coincided with periods of low adult and juvenile densities and vice versa, except in autumn when peaks in egg production and adult population densities were coincident. In this period, mean daily egg production rates reached a maximum of 4–5 eggs per female, when surface water temperature was 17–18°C. Egg production rates declined drastically in winter and were completely arrested when surface temperatures dropped to 10–12°C. In March, daily egg production rates began to increase again with an increase in ambient temperatures, reaching a maximum at the end of August. In the laboratory, as in the field, mean daily egg production rates were positively correlated with temperature, with values ranging from 2.2 ± 0.3 (16°C) to 8.9 ± 2.6 (30°C) (mean ± S.D.) eggs per female per day. At 32°C, P. xiphophorus females survived but did not reproduce. At 34°C, all specimens died after a few days. In terms of total egg production for the entire female lifespan, maximum values occurred at 16°C and minimum at 24°C. Temperature also dramatically affected female life span, which was shorter at higher temperatures. Development time of eggs decreased with increasing temperature, as also development time from egg to adulthood. Remating was necessary for the continued production of fertile eggs at 16°C because female life span was longer. The unique egg-laying behaviour in this species may ensure higher survival rates of egg stages compared to free-spawning and egg-carrying calanoid species. After releasing the egg pair, the female swims over the eggs with a rotatory motion, secreting a substance which facilitates the adhesion of the eggs to the bottom; she then continues to swim over the eggs until they are attached. Although egg production rates in this species are low compared to other pelagic copepods, they are within the range of values reported for egg-carrying species. The greater fecundity at higher temperatures compared to other subtemperate species indicates that the species is well adapted to the higher temperatures of coastal lagoons and brackish water lakes where it contributes to the biofouling community.     

Modelling the long-term behaviour of radiocaesium and radiostrontium in two Italian lakes

The present paper describes the application of a state-of-the-art model to two lakes in central Italy (Trasimeno and Monterosi) for the assessment of migration parameters of (137)Cs and (90)Sr (migration velocity to sediment, transfer rates from sediment to water and to bottom sediment). Applications of a compartment model and a model based on the diffusion equation to predict the behaviour of pollutants in water and through bottom sediment are presented and discussed. The application of the diffusion equation shows some difficulties of a general nature and typical of such a modelling approach. Moreover, there is no evidence of significant improvements of the model performances when the diffusion equation is applied. Very low levels of sedimentation rate of suspended matter in Lake Monterosi were evaluated by the quantitative assessment of radiocaesium migrating to bottom sediment. This suggests that, in this lake, the removal of radionuclide from the water column is mainly due to the turbulent mixing of bottom sediment causing radionuclide burial.     

Chemical recycling of poly(ethylene terephthalate) (pet) by hydrolysis and glycolysis

In this paper we review an interesting method of PET recycling, i.e. chemical recycling; it is based on the concept of depolymerizing the condensation polymer through solvolytic chain cleavage into low molecular products which can be purified and reused as raw materials for the production of high-quality chemical products. In this work our attention is confined to the hydrolysis (neutral, acid and alkaline) and glycolysis processes of PET chemical recycling; operating conditions and mechanism of each method are reported and described. The neutral hydrolysis has an auto accelerating character; two kinetic models have been proposed: an half-order and a second order kinetic model. The acid hydrolysis could be explained by a modified shrinking core model under chemical reaction control and the alkaline hydrolysis by a first-order model with respect to hydroxide ion concentration. To describe glycolysis, two different kinetic models have been proposed where EG can act or not as internal catalyst. Further experimental and theoretical investigations are required to shed light on the promising processes of PET chemical recycling reviewed in this work.     

Ozone sensitivity of currant tomato (Lycopersicon pimpinellifolium), a potential bioindicator species

The wild tomato species Lycopersicon pimpinellifolium (currant tomato) was exposed to different O3 concentration, both in controlled environment fumigation facilities and in open-top chambers, to assess its sensitivity and to verify its potential as a bioindicator plant. Plants appeared particularly sensitive to O3 at an early stage of growth, responding with typical chlorotic spots within 24 h after exposure to a single pulse of 50 ppb for 3 h, and differentiating peculiar symptoms, such as reddish necrotic stipples, bronzing and extensive necrosis, depending on O3 concentration. Histo-cytochemical investigations with 3,3'-diaminobenzidine, to localize H2O2, and Evans blue, to detect dead cells, suggested that currant tomato sensitivity to O3 could be due to a deficiency in the anti-oxidant pools. The combination of these stainings proved to be useful, either to predict visible symptoms, early before their appearance, and to validate leaf ozone injury.     

Long-term effects of aided phytostabilisation of trace elements on microbial biomass and activity, enzyme activities, and composition of microbial community in the Jales contaminated mine spoils

We studied the effectiveness of remediation on microbial endpoints, namely microbial biomass and activity, microbial and plant species richness, of an As-contaminated mine spoil, amended with compost (C) alone and in combination with beringite (B) or zerovalent iron grit (Z), to increase organic matter content and reduce trace elements mobility, and to allow Holcus lanatus and Pinus pinaster growth. Untreated spoil showed the lowest microbial biomass and activity and hydrolase activities, and H. lanatus as sole plant species, whereas the presented aided phytostabilisation option, especially CBZ treatment, significantly increased microbial biomass and activity and allowed colonisation by several plant species, comparable to those of an uncontaminated sandy soil. Microbial species richness was only increased in spoils amended with C alone. No clear correlation occurred between trace element mobility and microbial parameters and plant species richness. Our results indicate that the choice of indicators of soil remediation practices is a bottleneck.