Deep drainage technique utilised for flood mitigation in low-land coastal areas of Australia during the late 1960s has resulted in the generation of sulphuric acid in soil by the oxidation of pyritic materials. Further degradation of the subsurface environment with widespread contamination of the underlying soil and groundwater presents a major and challenging environmental issue in acid sulphate soil (ASS) terrains. Although several ASS remediation techniques recently implemented in the floodplain of Southeast Australia including operation of gates, tidal buffering and lime injections could significantly control the pyrite oxidation, they could not improve the long-term water quality. More recently, permeable reactive barriers (PRBs) filled with waste concrete aggregates have received considerable attention as an innovative, cost-effective technology for passive in situ clean up of groundwater contamination. However, long-term efficiency of these PRBs for treating acidic groundwater has not been established. This study analyses and evaluates the performance of a field PRB for treating the acidic water over 2.5 years. The pilot-scale alkaline PRB consisting of recycled concrete was installed in October 2006 at a farm of southeast New South Wales for treating ASS-impacted groundwater. Monitoring data of groundwater quality over a 30 month period were assessed to evaluate the long-term performance of the PRB. Higher pH value (~pH 7) of the groundwater immediately downstream of the PRB and higher rates of iron (Fe) and aluminium (Al) removal efficiency (>95%) over this study period indicates that recycled concrete could successfully treat acidic groundwater. However, the overall pH neutralising capacity of the materials within the barrier declined with time from an initial pH 10.2 to pH 7.3. The decline in the performance with time was possibly due to the armouring of the reactive material surface by the mineral precipitates in the form of iron and aluminium hydroxides and oxyhydroxides as indicated by geochemical modelling.

Soluble phosphate is a common ingredient of fertilizer used in agriculture production all over the world. This chemical mixed with soil is transported into the water and marine environment via rainfall causing a range of environmental problems such as toxic algae bloom. Kaolin clay is a common material found in soil and is used as a model system to understand the effects of phosphate adsorption on the flocculation/dispersion of the clay slurries. In the topics, torrential downpours are common. The large water flow will easily disperse the unflocculated or weakly flocculated sediments over a wide area including river and marine environments. Phosphate adsorption was found to weaken the interparticle forces between clay platelets in the slurries. At high enough concentration, it will completely deflocculate the clay slurries, i.e. the net interparticle force is repulsive. A deflocculated slurry is characterised by a low viscosity and no yield stress. As a result, it is much easier to disperse this slurry over a wide area possible even in a small downpour. This study will present the flow and yield stress behaviour of kaolin clay slurries under the influence of adsorbed phosphate.

In this study, slurry photocatalytic oxidation process was investigated for natural organic matter removal from aqueous humic acid solutions by using different titanium dioxide (TiO₂) under UV-A irradiation. Bench scale experimental studies were conducted at different humic acid concentration at the range of 10-50 mg/L and different pH. Anatase and mixed-phase anatase-rutile TiO₂ nano particles used in the photocatalytic reactor. The results were evaluated in terms of the parameters that are specific to organic matter content such as dissolved organic carbon concentration, ultraviolet absorbance at 254 nm (UV₂₅₄), specific ultaviolet absorbance at 254 nm, and color (VIS₄₀₀). It was observed that increasing humic acid concentration decreases photocatalytic degradation efficiency. The reactivity of the mixed-phase anatase-rutile (Degussa P-25) TiO₂ was greater than individual anatase particles and the highest efficiency was observed at pH 3 for anatase TiO₂.

Studies concerning mycotoxins involve activities of relevant potential for furthering knowledge in the fields of toxicology and environmental analysis. Using bioanalytical methods (biosensors, histochemistry), the conducted research aims at contributing to raising the awareness of local, national, and international media in relation to the safety of obtaining and processing vegetal and animal foods, by analyzing the possible effects of aflatoxins and ochratoxins, promoting animal health, food hygiene, in view of ensuring animal and human health. The study using laboratory animals (mice) while being part of one of the current national research directions, also holds international priority, by its contribution to a better understanding of several fundamental mechanisms of life at molecular level and to the characterization of certain biological processes that appear in mycotoxicosis.

The present work aims to assess the hazard for human health related to CO₂ anomalous concentrations in air emitted from dry gas vents located in the NE area of Mt. Amiata volcano (Tuscany, central Italy). A geochemical multi-methodological approach is adopted to determine the composition and the flux rate of the gas discharges in order to establish (1) the origin of the gas vents and (2) the behaviour of the discharged gases in the areas surrounding the emission sites. The gas vents are hosted within sub-circular morphological depressions (0 ~ 10-30 m), which likely originated by the collapse of cavities formed at shallow depth in the ground by dissolution of Triassic anhydrite formations and recent travertine deposits. CaCO₃ and CaSO₄ dissolution is mainly related to the underground circulation of CO₂-rich fluids whose hydrological pattern is regulated by local and regional tectonics. The CO₂-rich (up to 996,070 μmol/mol) gases tend to accumulate within the topographic lows, thus creating a sort of CO₂ ponds, and the knowledge of their evolution in time and space is important to evaluate the related hazard. Consequently, a conceptual model of CO₂ diffusion in air is developed to understand the dynamic of the CO₂ accumulation/dispersion process based on (1) a 24-h continuous measurement of the CO₂ flux from one of the main emission sites and (2) the recording of the main meteoric parameters, i.e. air temperature, wind direction and speed to check their influence. The results indicate that the threshold of CO₂ concentrations considered dangerous for the human health is frequently overcome. Moreover, when meteoric conditions, i.e. low wind and cloudy weather, did not allow a rapid dispersion of the gas phase emitted from the dry vents, CO₂-rich clouds periodically overflowed the morphological depressions for several tens of meters without any significant mixing with air. On the basis of these considerations, the monitoring of the output rate from the main gas emissions, combined with the continuous control of the local meteorological parameters, may be considered an efficient procedure to mitigate the CO₂ hazard deriving from dry gas vents. An improvement of the protocol can be achieved in case of installations of CO₂ sensors located in the most sensitive areas and connected to a telemetry system able to transmit the data in real time to the closest Civil Defence centre. The CO₂ degassing sites can also represent a tourist attraction after the installation of suitable metallic fences and a proper campaign of information about these natural phenomena.

A yearlong (December 2003 to February 2005) monitoring program was undertaken for urban roadside measurement of benzene, toluene, ethyl benzene, m- and p-xylene, and o-xylene (BTEX) at three different sites of Kolkata, India. The concentrations of monoaromatic hydrocarbons were found to be sufficiently high. Chemical mass balance model was applied to identify the sources and estimate their percentage contribution. Vehicular exhaust emission was found to be the dominant source of the target compounds and contributed 38.8-44.8% toward total volatile organic compound (VOC) level. Assuming that the vehicular exhaust fraction of the ambient BTEX level was due to the vehicular activity in the adjacent road of the monitoring site, vehicular emission factors for individual VOCs were estimated by running CALINE4 dispersion model in an inverse way. The total emission factor, average for all vehicles, was found to be in the range of 9.1 to 43.1 mg vehicle⁻¹ km⁻¹ for BTEX. From the measured vehicular composition during sampling, the category-wise emission factors for light-duty vehicles (LDVs), medium-duty (MDVs), and heavy-duty vehicles (HDVs), were also estimated by constrained nonlinear regression analysis. The emission factor of benzene for heavy, medium, and light vehicles was found to be 13.4, 21.0, and 31.2 mg vehicle⁻¹ km⁻¹ respectively.

We report observations of primary and secondary atmospheric pollutants such as nitrogen oxides, sulfur dioxide, toluene, and ozone during the period February 2002 to August 2003 in Puertollano, an industrial area located in central-southern Spain. The measurements were performed using a commercial differential optical absorption spectroscopy instrument. From the hourly data, we have analyzed the mean seasonal levels and the daily evolution and we have examined the occurrence of elevated pollution episodes. The daily cycles of NO, NO₂, SO₂, and toluene were characterized by an early-morning maximum whereas O₃ peaks were monitored around noon. Seasonally, the highest hourly mean concentrations of NO, NO₂, SO₂, and toluene, 14.2, 27.0, 34.4, and 12.1 μg m⁻³ respectively, were found in the winter while O₃ summer levels reached 119.1 μg m⁻³. The dataset presented here shows episodic occurrences of elevated concentrations that exceeded the maximum levels established in the European Directives. For instance, hourly values for SO₂ were repeatedly measured above 350 μg m⁻³. During the period of measurements, the O₃ thresholds (i.e., hourly value of 240 μg m⁻³) defined to protect the human health have also been exceeded numerous times. Finally, we investigate daily and seasonal patterns in pollution levels within the context of local meteorology and photochemistry, vehicular traffic, and industrial emissions.

Cr(VI) is a well-known highly toxic metal, considered a priority pollutant. Industrial sources of Cr(VI) include leather tanning, cooling tower blowdown, plating, electroplating, anodizing baths, rinse waters, etc. This article includes a survey of removal techniques for Cr(VI)-contaminated aqueous solutions. A particular focus is given to adsorption, membrane filtration, ion exchange, and electrochemical treatment methods. The primary objective of this article is to provide recent information about the most widely used techniques for Cr(VI) removal.

Risk assessment of trace-metal contamination in soils requires predictive models that take into account the interaction of metal ions with other cations (e.g., H⁺ and Ca²⁺) that can change the speciation of trace metals in solution and compete for binding sites on plant roots thus affecting metal uptake and toxicity. Acid-base titrations were used to estimate the types and quantity of cation-binding sites on fresh pea (Pisum sativum L. cv. Lincoln) roots and their binding strength with protons. The roots were found to have three types of cation-binding sites with site densities of 190, 382, and 347 μmolc g⁻¹ (dry weight), respectively. The binding strength with H⁺ was indicated by the equilibrium formation constants (K HLj ). The logK HLj values under different ionic strengths were determined. At zero ionic strength, the logK HLj values are estimated to be 2.5, 5.5, and 8.3, respectively. Complementary experiments were used to validate the titration results. These included an ion exchange experiment, an experiment with HCl extractions, and a KOH neutralization method. Estimates from all four methods were consistent under the experimental conditions. The quantification of the binding capacity and the characteristics of these binding sites will assist in the development of more appropriate solution speciation models that incorporate biotic ligands. The derived parameters will provide the basis on which further development of a biotic ligand model is dependent.

The removal of naphthalene from aqueous solutions by filtration using columns filled with sand and natural vermiculite and sand and hydrophobic vermiculite in different proportions of 2%, 5%, and 10% was evaluated. Batch experiments had shown that the removal was higher than 90% when the filled adsorbent was constituted by 10% of hydrophobic vermiculite. When vermiculite was in lower concentration, that is, 2% and 5%, the removal percentage was lower than 74%. The removal of the naphthalene by the column filled with sand and natural vermiculite did not exceed 25%. The capacity of the columns was tested passing four volumes of aqueous solution of 0.01 mol L⁻¹ naphthalene. After the third volume, the capacity dropped but still retained the major part of pollutant. However, the removal can be reached in higher levels (higher than 90%) when it is filled with 10% of modified vermiculite and increasing the length of the column. With 5% of vermiculite, it is possible to remove 94%, increasing the length of column by a factor of 1.1 times, that is, increasing the original length of 25 to 27.5 cm. The results had demonstrated that the columns are efficient in the removal of the naphthalene and bring speculations to remove other possible organic compounds.