Normative regulations on benzene in fuels and urban management strategies are expected to improve air quality. The present study deals with the application of self-organizing maps (SOMs) in order to explore the spatiotemporal variations of benzene, toluene, ethylbenzene, and xylene levels in an urban atmosphere. Temperature, wind speed, and concentration values of these four volatile organic compounds were measured after passive sampling at 21 different sampling sites located in the city of Trieste (Italy) in the framework of a multi-year long-term monitoring program. SOM helps in defining pollution patterns and changes in the urban context, showing clear improvements for what concerns benzene, toluene, ethylbenzene, and xylene concentrations in air for the 2001–2008 timeframe.

In recent years, much attention has been devoted in developing inexpensive or alternative systems for treating acid mine drainage (AMD). Manganese is a common component of AMD, and it is traditionally removed by precipitation. However, in order to meet the standard limits for discharging, usually <1 mg L, it is necessary to raise the pH above 10 which implies in high consumption of reagents and a final pH that does not meet the required value for discharging. This study investigated the removal of manganese from an acid mine effluent and laboratory solutions by using an industrial residue consisted of manganese dioxide (MnO). The pH of the acid effluent is around 2.7, and the manganese concentration is approximately 140 mg L. Batch experiments assessed the influence of pH and the efficiency of manganese dioxide (MnO) in the Mn removal. In the presence of MnO, the metal concentration meets the discharging limit at pH range of 6.8 to 7.2. Experiments carried out with columns packed with MnO assessed the influence of the flow rate on the process. Best results were obtained for columns fed with mine water neutralized with limestone at pH 7.0 and a residence time of 3.3 h. The maximum manganese loading capacity for MnO was around 14 mg g. RAMAN spectroscopy showed that the MnO is essentially constituted of pyrolusite. In addition, the solid hausmannite (MnO) was observed on the surface of the MnO residue after its contact with the Mn solution.

Arrival of tar balls to the Goa coast during pre- and southwest monsoon seasons has been a regular phenomenon in the past few years. In one such event, we observed tar ball deposits along the Goa coast during August 2010, April 2011 and May 2011 when no oil spill was reported in the Arabian Sea (AS). The only source for the formation of tar balls could be the spill/tanker-wash from the tankers passing through the international tanker routes across the AS. Assuming this, an attempt has been made to simulate surface winds, currents and tar ball trajectories for August 2010 using hydrodynamics and particle tracking models. Tar ball particles were released numerically at eight locations in the AS, and five of them reached the Goa coast, matching reasonably well with the observations. The present study confirms our view that the source of these tar balls is the accidental spills or tanker-wash along the international oil tanker route in the AS. A review of the global scenario of tar ball study is also presented in the Introduction.

Knowledge of the levels of both total metal content and metal bioavailability is critical for understanding the long-term effects of liming on soil chemistry and potential metal uptake by biota. In the present study, the long-term effects of liming on metal bioavailability in soils contaminated by smelter emissions were assessed in eroded and stable uplands in the Sudbury region, Ontario, Canada. Analytical results revealed that total metal and nutrient contents of the soil matrix are not dominantly in forms available for plant uptake for these soils. On average, only 1 and 1.1 % of total copper and nickel, respectively, were phytoavailable. Landscape topography, site stability, and smelter proximity all play an important role in metal accumulation in the surface organic and mineral horizons of regional soils. The levels of total and bioavailable elements for eroded sites were always smaller for stable and reference sites. The pH in limed sites was significantly higher, ranging from 4.12 to 6.75, in the humus form compared to unlimed areas, even 20 to 30 years following applications of the crushed dolostone (liming). No significant differences between limed and unlimed areas were found for total metal and nutrient contents. Interestingly, in the higher pH limed areas, the levels of bioavailable Al, Co, Cu, Fe, K, Mn, Ni, and Sr were lower than on unlimed areas. © 2013 Springer Science+Business Media Dordrecht.

In this study, the performance of a laboratory-scale soil aquifer treatment (SAT) system was investigated and treatability studies were done in order to determine organic matter removal from synthetic wastewater (SWW) and secondary treated real wastewater (RWW). The SAT system was constructed in laboratory conditions and treatability studies were conducted using soil columns, which were packed with silt loam soil samples. Each column was equipped with a series of ports at multiple depths from soil surface (10, 20, 30, 50, and 75 cm) to collect water samples. Two operational cycles were applied to represent the influence of different wetting and drying periods during wastewater application. Dissolved oxygen, chemical oxygen demand (COD), and total organic carbon (TOC) concentrations were measured in all samples. Average removal values of 61.4 % (COD) and 68.2 % (TOC) were achieved by in SWW and of 58.3 % (COD) and 51.1 % (TOC) in RWW in 55 and 25 weeks of operation, respectively. These results indicated that the performance of the columns operated with SWW was better than the performance of the columns operated with RWW. In essence, the easily biodegradable portion of organic matter was quickly consumed by microorganisms in the first 10 cm of the columns where oxygen levels peaked. Complex organic compounds that are likely to be found in RWW could thus be removed when longer residence times were achieved through the columns. When the removal performances achieved with different operating cycles were compared for each wastewater, it could be seen that longer wetting and longer drying periods yielded higher removal efficiencies in RWW and vice versa in SWW. © 2013 Springer Science+Business Media Dordrecht.

This paper addresses the oxidation by ultraviolet radiation of methylparaben, a ubiquitous and suspicious preservative which is massively added to cosmetics and personal care products. Experiments included pH and temperature variation, as well as several experimental conditions such as presence/absence of hydrogen peroxide, titanium dioxide, or some different water matrix (surface water or ground water). Results were evaluated under the line source spherical emission model, so quantum yield was the adequate target variable for explaining the process. A modified Arrhenius correlation including pH level was used for modelling the whole system.

Twenty-one plant leaf materials were screened for benzene adsorption efficiency in the static system, and the leaf material from Dieffenbachia picta, Acrostichum aureum, Ficus religiosa, Lagerstroemia macrocarpa, Alstonia scholaris, and Dracaena sanderiana were found to have high potential for benzene removal. The relation between quantity and composition of wax to benzene removal efficiency was studied. Although high quantities of wax occurred in some leaf materials, low benzene removal was clearly found if compared with other plant materials with the same wax quantity. Alpha-linoleic acid and dodecyl cyclohexane were found to be the main composition in plant leaf materials with high benzene adsorption, and it might be a key factor for benzene removal.

The in-depth knowledge on management and reducing annual acidic pollution is important for improving the sustainable livelihood of people living in areas with acid sulphate soils (ASS). This study involved a long-term (2001–2006), large-scale canal water quality monitoring network (87 locations) and a field experiment at nine sites to quantify the dynamic variability of acidic pollution and its source in a coastal area with ASS in the Mekong River Delta of Vietnam. Widespread acidic pollution (pH <5) of surface water occurred at the beginning of the rainy season, while pH of the canal water remained high (7–8) at the end of the rainy season and during the dry season. The study identified canal embankment deposits, made of ASS spoils from canal dredging/excavation, as the main source of acidic pollution in the surrounding canal network. The findings suggested that there was a linkage between the amount of acidic loads into canal networks and the age of the embankment deposits. The most acute pollution (pH ~ 3) occurred in canals with sluggish tidal water flow, at 1–2 years after the deposition of excavated spoils onto the embankments in ASS. The amount of acidic loads transferred to the canal networks could be quantified from environmental parameters, including cumulative rainfall, soil type and age of embankment deposits. The study implied that dredging/excavation of canals in ASS areas must be carried out judiciously as these activities may increase the source of acidic pollution to the surrounding water bodies.

Perfluorooctane sulfonate (PFOS), which has numerous uses besides being an ingredient in the formulation of aqueous film-forming foams, is considered as an emerging pollutant of increasing public health and environmental concern due to recent reports of its worldwide distribution, environmental persistence and bioaccumulation potential. In an attempt to recommend a 'risk-based' remediation strategy, this study investigates the removal of PFOS from impacted waters and fixation of PFOS in impacted soils using a novel modified clay adsorbent (MatCARE™, patent number 2009905953). Batch adsorption tests demonstrated a much faster adsorption kinetics (only 60 min to reach equilibrium) and remarkably higher PFOS adsorption capacity (0.09 mmol g-1) of the MatCARE™ compared to a commercial activated carbon (0.07 mmol g -1). Treatability studies, performed by treating the PFOS-contaminated soils with the MatCARE™ (10 % w/w) and then incubating at 25 and 37 C temperatures maintaining 60 % of the maximum water holding capacity of the soils for a period of a year, demonstrated a negligible release (water extractable) of the contaminant (only 0.5 to 0.6 %). The fixation of PFOS in soils by the new adsorbent was exothermic in nature. Soils with higher clay and organic matter content, but lower pH values, retained PFOS to a much greater extent. A cost analyses confirmed that the MatCARETM could be an economically viable option for the 'risk-based' remediation of PFOS in contaminated waters and soils. © 2013 Springer Science+Business Media Dordrecht.

With the constant development of new ionic liquids, the understanding of the chemical fate of these compounds also needs to be updated. To this effect, the interaction of a number of novel ionic liquids with soils was determined. Therefore, three novel headgroups (ammonium, phosphonium, or pyrrolidinium) with single or quaternary substitution were tested on a variety of soils with high-to-low organic matter content and high-to-low cation exchange capacity, thereby trying to capture the full range of possible soil interactions. It was found that the ionic liquids with single butyl alkyl chain interacted more strongly with the soils (especially with a higher cation exchange capacity), at lower concentrations, than the quad-substituted ionic liquids. However, the quad-substituted ionic liquids interacted more strongly at higher concentrations, due to the double-layer formation, and induced stronger dipole interaction with previously sorbed molecules.