Aromatic photonitration in homogeneous and heterogeneous aqueous systems

This work describes the nitration of aromatics upon near-UV photolysis of nitrate and nitrite in aqueous solution and upon photocatalytic oxidation of nitrite in TiO2 suspensions. Phenol is used in this work as a model aromatic molecule and as a probe for *NO2/N2O4. The photoinduced nitration of phenol in aqueous systems occurs upon the reaction between phenol and *NO2 or N2O4, and is enhanced by the photocatalytic oxidation of nitrite to *NO2 by TiO2. Aromatic photonitration in the liquid phase can play a relevant role in the formation of nitroaromatics in natural waters and atmospheric hydrometeors, thus being a potential pathway for the condensed-phase nitration of aromatics. Furthermore, the photoinduced oxidation of nitrite to nitrogen dioxide suggests a completely new role for nitrite in natural waters and atmospheric aerosols.     

Tire debris organic extract affects Xenopus development

Tire debris (TD) and its organic components were identified as a main source of PM10 atmospheric and water pollution. Because few data are available on the embryotoxic effects of TD organic components, the lethal and teratogenic potential of tire debris organic extract (TDOE) was evaluated using the frog embryo teratogenesis assay-Xenopus (FETAX), coupled with a histopathological screening of the survived larvae. From stage 8 to stage 47, Xenopus laevis embryos were exposed to TDOE at concentrations of 50, 80, 100, 120 and 140 mg/L. The results showed 50 mg/L TDOE to be the non-observable effect concentration (NOEC). TDOE mortality at 80 mg/L was significantly higher than the control, but did not increase further with higher concentrations. A good concentration-response was observed for percentages of malformed larva and from 80 mg/L on these percentages were significantly higher than the control. Therefore, probit analysis gave a 144.6 mg/L TC50. At 120 and 140 mg/L, many larvae were plurimalformed. The most frequent alterations observed were abnormal gut coiling, microphthalmia, monolateral anophthalmia, and narrowing eyes. The histological screening mainly revealed ocular malformations such as double retina, retina nervous cell layer coiling, and altered lens. Moreover severe vacuolisation and necrosis were scored in liver and axial musculature. These results strongly support the assumption that TDOE is a powerful teratogen for X. laevis.     

Heavy Metal Content in Xylem Sap (Vitis Vinifera) from Mining and Smelting Areas

No data are available on the content of heavy metals in the xylem sap of grapevines growing in contaminated areas. The aim of this work was to obtain data on the concentration of Pb, Zn, Cd and Cu in the xylem sap of grapevine (Vitis vinifera) cultivar Monica (ungrafted), growing near contaminated sites: a smelter, an abandoned and an active mine, and to investigate relationships between xylem sap mineral composition and the heavy metal content of the soil. The concentrations of Pb, Zn, Cd and Cu in the sap were enhanced compared to that of the soil, ranging from 4.3 to 611.4 µg Pb , 801 to 6176 µg Zn , 2.5 to 45 µg Cd and 19.8 to 161 µg Cu . Dry matter of xylem sap was significantly related to the heavy metals content in xylem saps, but no significant relationship between the metals in sap and total and DTPA/TEA extractable metal fraction in soil was found.     

Sixty years of habitat decline: impact of land-cover changes in northern Italy on the decreasing ortolan bunting <Emphasis Type=Italic>Emberiza hortulana</Emphasis>

Habitat loss and degradation are main global threats to biodiversity, and land-use changes in agriculture-dominated landscapes are crucial for an important portion of biodiversity, especially in Europe. We evaluated the effects of land-use changes (1954–2012) on a threatened species, the ortolan bunting, in an agricultural area crucial for its conservation in Italy. We built a distribution model for ortolan bunting in current landscapes and then re-projected it to past scenarios (1954 and 1999–2000). We evaluated the most important land-use changes occurred and estimated their effects on habitat suitability. Bunting occurrence was mostly affected by the extent of grassland (positively; used as foraging/breeding ground), shrubland (quadratic effect; perches/shelter), forest and urbanized land (negatively), and by solar radiation (positively) and slope (quadratic), consistent with other studies carried out especially in southern Europe. The potential distribution of the species was much larger in the past: the estimated decline in suitable habitat is 44–72 % (since 1999–2000/1954), coherent with historical data suggesting strong decline and contraction. Changes in suitability (1954–2012) were mostly associated with changes in the cover of forest, vineyards and abandoned areas (negatively), and shrubland (positively). Land-use/land-cover changes are the main drivers of species occurrence and of habitat decline. The heterogeneous landscape of hilly/low-mountain sites in this area, characterized by a mix of habitats offering complementary resources to ortolan buntings and other species of conservation concern, is currently threatened by abandonment and intensification, but its maintenance may be promoted by a correct definition of Rural Development Programme measures.     

Optimization of the electrocoagulation process for the removal of copper, lead and cadmium in natural waters and simulated wastewater

Chemical, electrochemical and flow variables were optimized to examine the effectiveness of the electrocoagulation process for the removal of copper, lead and cadmium. The electrochemical process, which uses electrodes of commercial laminate steel, was applied to simulated wastewater containing 12 mg dm(-3) of copper, 4 mg dm(-3) of lead and 4 mg dm(-3) of cadmium. The optimum conditions for the process were identified as pH=7, flow rate=6.3 cm(3) min(-1) and a current density between 31 and 54 A m(-2). When the electrode geometric area and time of electrolysis reached critical values, the copper removal reached a maximum value of 80%. A linear relationship was identified between the current density and the mass of generated sludge. In addition, a linear relationship was found between specific energy consumption and current density. The results of this investigation provide important data for the development of an industrial-scale electrolytic reactor.     

Role of volcanic dust in the atmospheric transport and deposition of polycyclic aromatic hydrocarbons and mercury

The role of volcanic ash as scavenger of atmospheric pollutants, in their transport and final deposition to the ground is examined. Attention is focused on polycyclic aromatic hydrocarbons (PAHs) and on particulate mercury (Hgp). The ash-fall deposits studied belong to the 2001 and 2002 eruptive activity of Mount Etna, Southern Italy, and were investigated at three (2001) and four (2002) sites downwind of the major tephra dispersal pattern. The dry deposition of mercury and PAHs was determined, and, in particular, a downward flux to the ground of PAHs (approximately 7.29 microg m(-2) per day) and mercury (750 ng m(-2) per day) was estimated in Catania from October 26 to October 28, 2002. Finally, evidence on the anthropogenic origin of PAHs scavenged from the troposphere by volcanic ash is supported by the analysis of PAH compositions in granulometrically homogeneous fractions.     

Combinations of Horizontal and Vertical Flow Constructed Wetlands to Improve Nitrogen Removal

Nitrogen removal in wetlands is achieved through two pathways: (a) N cycling and (b) storage. N cycling is a permanent removal pathway. There has been an increasing interest in the development of technologies to alleviate permanent nitrogen removal limitation in constructed wetlands by ensuring prevalence of conditions enhancing N cycling. The purpose of this study is to review an emerging technology of vegetated submerged bed constructed wetland system aimed at improving nitrogen removal in wetlands through rational system design. The design and performance of this system type is evaluated. The oxygen transfer capacity and nitrogen removal mechanisms on system performance are evaluated. Constructed wetland combinations most commonly consist of vertical flow (VF) and horizontal flow (HF) beds where VF and HF are aimed at nitrification and denitrification, respectively. Nitrate nitrogen accumulation is the most limiting factor in typical VF based systems.     

Pendimethalin and oxyfluorfen degradation under two irrigation conditions over four years application

A four-year field study was conducted to determine the effect of pluviometric conditions on pendimethalin and oxyfluorfen soil dynamics. Adsorption, dissipation and soil movement were studied in a sandy loam soil from 2003 to 2007. Pendimethalin and oxyfluorfen were applied every year on August at 1.33 and 0.75 kg ha^?1, respectively. Herbicide soil concentrations were determined at 0, 10, 20, 40, 90 and 340 days after application (DAA), under two pluviometric regimens, natural rainfall and irrigated (30 mm every 15 days during the first 90 DAA). More than 74% of the herbicide applied was detected at the top 2.5 cm layer for both herbicides, and none was detected at 10 cm or deeper. Pendimethalin soil half-life ranged from 10.5 to 31.5 days, and was affected mainly by the time interval between application and the first rain event. Pendimethalin soil residues at 90 DAA fluctuated from 2.5 to 13.8% of the initial amount applied, and it decreased to 2.4 and 8.6% at 340 DAA. Oxyfluorfen was more persistent than pendimethalin as indicated by its soil half-life which ranged from 34.3 to 52.3 days, affected primarily by the rain amount at the first rainfall after application. Oxyfluorfen soil residues at 90 DAA ranged from 16.7 to 34.8% and it decreased to 3.3 and 17.9% at 340 DAA. Based on half-life values, herbicide soil residues after one year, and soil depth reached by the herbicides, we conclude that both herbicides should be considered as low risk to contaminate groundwater. However, herbicide concentration at the top 2.5 cm layer should be considered in cases where runoff or soil erosion could occur, because of the potential for surface water contamination.