Degradation of chlortoluron in water disinfection processes: a kinetic study

The kinetics of the reaction between chlortoluron, a phenylurea herbicide [N'-(2-hydroxy-4-methyl-5-chlorophenyl)-N,N-dimethylurea], and hypochlorite, the active species in water disinfection processes involving chlorine, were investigated by HPLC-UV and HPLC-electrospray ionisation mass spectrometry (HPLC-ESI-MS). In particular, the concentrations of the main chlortoluron by-products were monitored as a function of time by HPLC-ESI-MS and a kinetic model was developed to fit the relevant curves. The results showed that chlortoluron degradation starts with two parallel pathways, namely, chlorination and hydroxylation of the aromatic ring, which are then followed by consecutive chlorination reactions, and after almost 2 weeks by ring opening and partial mineralisation, as confirmed by head-space solid-phase microextraction gas chromatography-MS (SPME-GC-MS) and total organic carbon (TOC) measurements. Kinetic constants for the first reactions of the overall process, under pseudo-first-order conditions (hypochlorite excess), were estimated by a fitting procedure.     

Assessing Major Ecosystem Types and the Challenge of Sustainability in Turkey

In recent years, Turkey has experienced rapid economic and population growth coupled with both an equally rapid increase in energy consumption and a vast disparity in welfare between socioeconomic groups and regions. In turn, these pressures have accelerated the destruction of productive, assimilative, and regenerative capacities of the ecosystems, which are essential for the well-being of the people and the economy. This paper describes the structure and function of major ecosystem types in Turkey and discusses the underlying causes of environmental degradation in the framework of economy, energy, environment, and ethics. From a national perspective, this paper suggests three sustainability-based policies necessary for Turkey's long-term interests that balance economic, environmental, and energy goals: (1) decoupling economic growth from energy consumption growth through the development of energy-efficient and renewable energy technologies; (2) linking economic efficiency and distributive justice of wealth and power through distributive and participatory public policies; and (3) integrating the economic and ecological systems through the internalization of externalities and ecosystem rehabilitation.     

A cost-effective screening method for pesticide residue analysis in fruits, vegetables, and cereal grains

This paper reports the results of studies performed to investigate the potential of applying thin layer chromatography (TLC) detection in combination with selected extraction and cleanup methods, for providing an alternative cost-effective analytical procedure for screening and confirmation of pesticide residues in plant commodities. The extraction was carried out with ethyl acetate and an on-line extraction method applying an acetone-dichloromethane mixture. The extracts were cleaned up with SX-3 gel, an adsorbent mixture of active carbon, magnesia, and diatomaceous earth, and on silica micro cartridges. The Rf values of 118 pesticides were tested in eleven elution systems with UV, and eight biotest methods and chemical detection reagents. Cabbage, green peas, orange, and tomatoes were selected as representative sample matrices for fruits and vegetables, while maize, rice, and wheat represented cereal grains. As an internal quality control measure, marker compounds were applied on each plate to verify the proper elution and detection conditions. The Rf values varied in the different elution systems. The best separation (widest Rf range) was achieved with silica gel (SG)--ethyl acetate (0.05-0.7), SG--benzene, (0.02-0.7) and reverse phase RP-18 F-254S layer with acetone: methanol: water/30:30:30 (v/v) (0.1-0.8). The relative standard deviation of Rf values (CV(Rf)) within laboratory reproducibility was generally less than 20%, except below 0.2 Rf, where the CVRf rapidly increased with decreasing Rf values. The fungi spore inhibition, chloroplast inhibition, and enzyme inhibition were found most suitable for detection of pesticides primarily for confirming their identity or screening for known substances. Their use for determination of pesticide residues in samples of unknown origin is not recommended.     

Trace elements in biodeposits and sediments from mussel culture in the Ria de Arousa (Galicia, NW Spain)

The trace elements present at highest concentrations were Cr and Zn, which probably originated from the dumping of effluent from a tanning factory. High proportions of these two elements were associated with the residual fraction. Biodeposits and sediments showed high concentrations of Cd and Pb in the reactive fraction, with a high proportion of the concentration in the reactive fraction being associated with carbonates. Nickel showed a higher degree of pyritization than the previous elements, although most of the Ni was associated with the residual and reactive fractions. Arsenic, Hg and Cu showed high degrees of pyritization, particularly below a depth of 5 cm. The results demonstrate that those elements with a high degree of pyritization may be released into the water through oxidation of the metal sulphides that they form when in suspension in oxic sea water, with the subsequent risk of increased bioavailability to benthic fauna.     

Mineralization of paracetamol in aqueous medium by anodic oxidation with a boron-doped diamond electrode

The degradation of 100ml of solutions with paracetamol (N-(4-hydroxyphenyl)acetamide) up to 1 g l(-1) in the pH range 2.0-12.0 has been studied by anodic oxidation in a cell with a boron-doped diamond (BDD) anode and a graphite cathode, both of 3-cm2 area, by applying a current of 100, 300 and 450 mA between 25 and 45 degrees C. Complete mineralization is always achieved due to the great concentration of hydroxyl radical (*OH) generated at the BDD surface, with release of NH4+ and NO3- ions. The mineralization rate is pH-independent, increases with increasing applied current and temperature, but decreases when drug concentration raises from 315 mg l(-1). Reversed-phase chromatography revealed a similar complex paracetamol decay in acid and alkaline media. Ion-exclusion chromatography allowed the detection of oxalic and oxamic acids as ultimate carboxylic acids. When the same solutions have been comparatively treated with a Pt anode, a quite poor mineralization is found because of the production of much lower *OH concentration. Under these conditions, the degradation rate is enhanced in alkaline medium and polymerization of intermediates is favored in concentrated solutions. Paracetamol can be completely destroyed with Pt and its kinetics follows a pseudo-first-order reaction with a constant rate independent of pH.     

Temporal variations in PAH concentrations in Quercus ilex L. (holm oak) leaves in an urban area

Temporal variations of polycyclic aromatic hydrocarbon (PAH) concentrations in leaves of a Mediterranean evergreen oak, Quercus ilex L., were investigated in order to assess the suitability of this species to biomonitor PAH air contamination. Leaf samples were collected at six sites of the urban area of Naples (Italy) and at a control site in the Vesuvius National Park, in May and September 2001, and in January and May 2002. PAH extraction was conducted by sonication in dichloromethane-acetone and quantification by GC-MS. In winter, leaf total PAH concentrations showed, at all the urban sites, values 2-fold higher than in all the other samplings, reflecting the temporal trend reported for PAH air contamination in the Naples urban area. Moreover, leaf PAH concentrations showed, at all the urban sites, a decrease in May 2002 after the winter accumulation. At the control site leaf PAH concentrations showed lower values and smaller temporal variations than at the urban sites. The findings support the suitability of Q. ilex leaves to monitor temporal variations in PAH contamination. The highest winter concentrations of total PAHs were due to the medium molecular weight PAHs that increased with respect to both low and high molecular weight PAHs. The medium molecular weight PAHs showed the same temporal trend both at the urban and remote sites.     

Evaluation of 38 years of radiological environmental data for the nuclear research facility in South Africa

Environmental monitoring has been conducted at the South African National Nuclear Research Facility (Necsa site) for the past 38 years. Included in this monitoring programme was the assessment of water, fish and sediment samples. The objective of this project was to review the data of these assessments to establish if the Necsa activities had any impact on the environment. An assessment of the management of discharge limits was included in the review. Fluctuations in the data reviewed can partly be ascribed to errors in sampling techniques and analysis methods, but mostly to external factors. Two main external factors identified during the review were: dilution effects based on the flowrate in the Crocodile River and the percentage of full capacity of the Hartbeespoort Dam, and the atmospheric fallout from nuclear weapons testing. In this project, the impact of these factors were investigated with the help of correlation coefficient calculations and graphs. It was concluded that the flowrate of the Crocodile River and percentage full capacity of the Hartbeespoort Dam did have an impact on the beta activity measured in water and fish samples, and the (nat)U activities measured in water samples. The measured fallout from nuclear weapons testing in the southern hemisphere also had an impact on the beta activity in water. The assessment of the environmental monitoring data also showed that accidental releases were measurable in the environment. The added routine impact to a member of the public downstream from Necsa was on average an annual dose of 0.54 microSv more than that to a person living upstream from Necsa, which is considered insignificant in international radiation protection norms. The conclusion can be made that the monitoring programme is successful in satisfying its main objective, which is to determine the effects of the discharges on the environment and the immediate population.     

Effect of indigenous bacterial activity on arsenic mobilization under anaerobic conditions

Batch biochemical leaching tests were carried out to investigate the mobility of arsenic from a contaminated soil collected from a French gold mining site. The specific objective of this research was to examine the effect of indigenous bacterial activity on arsenic mobilization under anaerobic conditions. In a first step, physical and chemical characterizations were performed to provide data concerning the liquid-solid partitioning and mobility of arsenic and other inorganic constituents. In a second step, batch bioleaching tests were conducted in shaker flasks to determine the effect of indigenous bacterial activity under different anaerobic conditions (i.e., addition of mineral nutrients and carbon sources) on arsenic mobilization. Results indicated that arsenic release during contact with deionized water was limited by its very low solubility in the interstitial solution and by the stability of the different arsenic compounds formed with the amorphous solid phases of the soil (mainly iron (oxy)hydroxides). However, an increased mobilization potential was observed over the long term under anaerobic conditions with indigenous bacterial activity enhanced by the addition of carbon sources.     

Organic carbon changes in the surface sediments of the Venice lagoon

The concentrations of total, inorganic and organic carbon in the surface sediment of the central part of the Venice lagoon (31-55 stations) during the month of June in 1987, 1993 and 1998 were recorded. In two stations: San Giuliano and Lido, samples were collected on a monthly basis for 1 year also in different periods. On an average, by considering the whole central lagoon, inorganic carbon (IC) and total carbon (TC) did not show significant changes. In contrast organic carbon (OC) had alternating trends showing a decrease from 1987 to 1993, due to the almost complete disappearance of huge macroalgal biomasses, and a marked increase from 1993 to 1998, because of the high sediment disturbance caused by the catching of the clam Tapes philippinarum Adams & Reeve which had colonised the sediment free of macrophytes. The carbon changes monitored in the two stations studied on a seasonal basis during different years not only confirmed such results, but also enhanced the effects of fishing activities at Lido station and those depending on the disappearance of macroalgae at S. Giuliano. Moreover, this paper underlines the importance of seagrass beds. In fact in the areas colonised by those plants the percentage of fine sediments and organic matter is on the increase, while erosive processes are contrasted.     

The quality of Albanian natural waters and the human impact

Albania possesses a wealth of aquatic ecosystems, many of enormous natural and biological value, such as the Lakes Ohrid, Prespa and Shkodra, glacial lakes, river valleys, and coastal lagoons. Although many habitats are highly polluted by inorganic and organic wastes, detailed knowledge on the water quality is still lacking. For the first time, an environmental assessment of the water quality is presented and the main polluting sources identified. As a consequence, a systematic control and the establishment of routine monitoring of surface and groundwater is proposed, which elucidates the present environmental state and helps to develop new strategies of waste and wastewater management. It would help allow Albania to reach an international standard in environmental protection, as a part of UNECE Convention, the Mediterranean Action Plan, the MAP/UNEP Medpol Program and the Basel Convention.