Hydrocarbon pollution fixed to combined sewer sediment: a case study in Paris

Over a period of two years (2000-2001), sediment samples were extracted from 40 silt traps (STs) spread through the combined sewer system of Paris. All sediment samples were analysed for physico-chemical parameters (pH, organic matter content, grain size distribution), with total hydrocarbons (THs) and 16 polycyclic aromatic hydrocarbons (PAHs) selected from the priority list of the US-EPA. The two main objectives of the study were (1) to determine the hydrocarbon contamination levels in the sediments of the Paris combined sewer system and (2) to investigate the PAH fingerprints in order to assess their spatial variability and to elucidate the PAH origins. The results show that there is some important inter-site and intra-site variations in hydrocarbon contents. Despite this variability, TH and PAH contamination levels (50th percentile) in the Parisian sewer sediment are estimated at 530 and 18 microg g(-1), respectively. The investigation of the aromatic compound distributions in all of the 40 STs has underlined that there is, at the Paris sewer system scale, a homogeneous PAH background pollution. Moreover, the study of the PAH fingerprints, using specific ratios, suggests the predominance of a pyrolytic origin for those PAHs fixed to the sewer sediment.     

Chlorination of bisphenol A: kinetics and by-products formation

The kinetics of initial chlorination of bisphenol A (BPA) was studied between pH 2 and 11 at room temperature (20 +/- 2 degrees C). pH Profile of the apparent second-order rate constant of the reaction of BPA with chlorine were modeled considering the elementary reactions of HOCl with BPA species and an acid-catalyzed reaction. The predominant reactions at near neutral pH were the reactions of HOCl with the two phenolate species of BPA (k = 3.10 x 10(4) M(-1)s(-1) for BPA- and 6.62 x 10(4) M(-1) s(-1) for BPA(2-)). At near neutral pH, half-life times of BPA were calculated to be less than 1.5 h for chlorine residual higher than 0.2 mg l(-1). Chlorination of synthetic treated waters spiked with BPA showed that BPA disappeared within 4 h and that chlorinated bisphenol A congeners were rapidly formed and remained in solution for up to 10-20 h when low chlorine dosages are applied (0.5-1 mg l(-1)). To limit their presence in drinking water networks, it is then necessary to maintain high chlorine residuals that rapidly produce and decompose chlorinated bisphenol A congeners.     

Heterogeneous and homogeneous catalytic ozonation of benzothiazole promoted by activated carbon: kinetic approach

Ozone oxidation combined with activated carbon adsorption (O(3)/AC) has recently started to be developed as a single process for water and wastewater treatment. While a number of aspects of aqueous ozone decomposition are well understood, the importance and relationship between aqueous ozone decomposition and organic contaminant degradation in the presence of activated carbon is still not clear. This study focuses on determining the contribution of homogeneous and heterogeneous reactions to organic contaminants removal in O(3)/AC system. Benzothiazole (BT) was selected as a target organic pollutant due to its environmental concern. A reactor system based on a differential circular flow reactor composed by a 19 cm(3) activated carbon fixed bed column and 1 dm(3) storage tank was used. Ozone was produced from pure and dry oxygen using an Ozocav ozone generator rated at 5 g O(3)h(-1). Experimental results show that BT removal rate was proportional to activated carbon dosage. Activated carbon surface contribution to BT oxidation reactions with ozone, increased with pH in absence of radical scavengers. The radical reaction contribution within the pH range 2-11 accounted for 67-83% for BT removal in O(3)/AC simultaneous treatment. Results suggest that at pH higher than the pH of the point of zero charge of the activated carbon dissociated acid groups such as carboxylic acid anhydrides and carboxylic acids present on activated carbon surface could be responsible for the observed increase in the ozone decomposition reaction rate. A simplified mechanism and a kinetic scheme representing the contribution of homogeneous and heterogeneous reactions on BT ozonation in the presence of activated carbon is proposed.     

Anaerobic PAH degradation in soil by a mixed bacterial consortium under denitrifying conditions

Polycyclic aromatic hydrocarbons (PAHs) are one of the main classes of contaminants in the terrestrial environment. Concentrations of biphenyl, fluorene, phenanthrene and pyrene were added to soil samples in order to investigate the anaerobic degradation potential of PAHs under denitrifying conditions. A mixed population of microorganisms obtained from a paddy soil was incubated for 20 days in anaerobic conditions in the presence of soil alone or with nitrate, adding, as electron donors, PAHs and, in some samples, glucose or acetate. At regular time intervals oxidation-reduction potential, PAHs concentration, microbial ATP and nitrate concentration into the solution were measured. Degradation trends for each hydrocarbon are similar under all conditions, indicating that the molecular conformation prevails over other parameters in controlling the degradation. Poor degradation results were obtained when PAHs were the only organic matter available for the inoculum, thus confirming the recalcitrance to degradation of these compounds. Biodegradation was influenced by the addition of other carbon sources. As better degradation results were generally obtained when acetate or glucose were added, the hypothesis of a co-metabolic enhancement of PAH biodegradation seems likely. Thus, anaerobic biodegradation of PAHs studied, biphenyl, fluorene, phenanthrene and pyrene, seems to be possible both through fermentative and respiratory metabolism, provided that low molecular weight co-metabolites and suitable electron acceptors (nitrate) are present.     

Treatment of a clinical analysis laboratory wastewater from a hospital by photo-Fenton process at four radiation settings and toxicity response

Environmental Science and Pollution Research - The photo-Fenton process was performed with four radiation settings to treat clinical analysis laboratory wastewater (CALWW) from a hospital, with the...     

Genotoxic effects of metals on human salivary gland tissue and lymphocytes as detected by the Comet assay

The etiology of salivary gland malignancies still remains unclear. Metal compounds are of special interest since they show ubiquitous presence in the environment, are present in many working places, and are accepted (co-)carcinogens in some other malignancies. Metals enter the body as xenobiotics by inhalation or ingestion. This study investigated the genotoxic potential of sodium dichromate (Na₂Cr₂O₇), nickel sulfate (NiSO₄), cadmium sulfate (CdSO₄) and zinc chloride (ZnCl₂) on human salivary gland cells and lymphocytes. Macroscopically healthy tissue of salivary glands was harvested from 46 patients during surgery and isolated to single cells by enzymatic digestion. The cells were incubated with Na₂Cr₂O₇, NiSO₄, CdSO₄ or ZnCl₂. Na₂Cr₂O₇ was also incubated in combination with the other metal compounds listed. Carcinogenic and co-carcinogenic effects of cadmium were tested by incubation with Na₂Cr₂O₇ and consecutive repair intervals. DNA damage and repair were evaluated by the Comet assay, determining DNA-strand breaks. The extent of damage was quantified using a digital analysis system. Na₂Cr₂O₇ produced significantly enhanced DNA-strand breaks in human salivary gland tissue and lymphocytes. All other metal compounds exerted no damaging effect on both cell types. Co-incubation of Na₂Cr₂O₇ with the other metals revealed a significant additive effect only for CdSO₄. Specific analysis of the influence of cadmium showed a reduction of DNA-repair after Na₂Cr₂O₇-induced strand breaks in salivary gland cells. This study provides evidence that exposure to distinct metals may significantly contribute to malignant salivary gland tumors. In consequence, further studies as epidemiological and toxicological data are warranted to determine the role of distinct metals as potential (co-) carcinogens.     

Dissolution behavior of metals from particulate matter emissions

Exposure to air particulate matter (PM) is linked to numerous health effects. In order to improve the understanding of the role of its metallic components, their solubility was examined by using serial short-contact dissolutions totalling 1?h and additional sequential contact periods of 1, 4, and 8 days. The dissolution experiments were performed in solutions containing the main biological electrolytes. ICPMS determinations were used to quantify the dissolved metals. The total compositions were determined after closed vessel microwave digestion. Large variations in the rate and completeness of the dissolutions were observed. Fast and extensive dissolutions within the short-contact time (e.g., Zn, Cd) as well as slow dissolutions persisting during the last contact period (e.g., Ni, Cu, Sb, Pb) were found for smelting emissions. The multi-element determinations also made it possible to identify relationships between dissolution of different metals and define gradual composition changes of residual PM. When comparing with dissolutions performed in de-ionized water, similar major fractions were observed at short-contact time for minor components of smelting or combustion emissions (e.g., V, Ni, Cd), suggesting a preponderance of easily available forms at the surface of the relatively inert particle cores. The use of these time sequential methods may help in (1) modeling metal partitioning in biological media and (2) investigating the causes of adverse effects attributed to air PM.     

Potential correlation between perfluorinated acids and liver morphology in East Greenland polar bears (Ursus maritimus)

In this study, residual concentrations of chlorpyrifos (CPF) were determined in feed (40) and fodder (25) samples collected from various locations of Tarai region of Uttarakhand. For extracting residues, liquid–liquid partition followed by alumina column clean up was used and the detection and quantification of residues was undertaken with the help of high-performance liquid chromatography using C18 column and diode array detector at 220?nm. Of the total 40 feed samples analyzed, 7 (17.5%) samples were found positive for CPF with the mean residual concentration of 0.058?µg?g^?1; while out of 25 fodder samples, CPF residues were detected in a single (4%) sample with residual concentration of 0.39?µg?g^?1. However, none of the feed or fodder samples contained CPF residues above the prescribed limit.     

Levels of plasma B-esterases and glutathione-S-transferase activities in three South American toad species

We determined the normal levels of butyrylcholinesterase (BChE), carboxylesterase (CbE), and glutathione S-transferases (GST) activities in three South American toad species in order to establish reference values for field pesticide monitoring purposes. Interspecies variations in B-esterase and GST activities were examined according to body mass. In addition, comparative inhibition of BChE and CbE activities using malaoxon, and chemical reactivation of malaoxon-inhibited BChE activity using pyridine-2-aldoxime methochloride (2-PAM) were investigated. Bufo fernandezae had average activity values for BChE: 17.31 mmol min^?1 ml^?1; CbE: 621.49 nmol min^?1 ml^?1 and GST: 1.94 mmol min^?1 ml^?1 while B. arenarum enzymatic average activities were BChE: 9.51 mmol min^?1 ml^?1; CbE: 270.07 nmol min^?1 ml^?1, and GST: 1.59 mmol min^?1 ml^?1; finally Bufo schneideri had enzymatic mean values of BChE: 2.08 mmol min^?1 ml^?1; CbE: 301.95 nmol min^?1 ml^?1, and GST: 1.60 mmol min^?1 ml^?1. Moreover, we found an allometric relationship between plasma BChE and CbE activities and body size for the three toad species. We suggest that B. fernandezae would be the species with a higher tolerance capacity to organophosphorous insecticides compared to the other toad species, while B. schneideri may be the most vulnerable toad species to field pesticide exposure, although some other factors (e.g., brain AChE sensitivity or pesticide metabolism by phosphotriesterases) should be also taken into account. The malaoxon-inhibited BChE activity of the three toad species was reactivated in the presence of 2-PAM, and it is recommended as a specific and sensitive methodology in the assessment of field exposure to OP insecticides together to compare BChE activity levels between OP-exposed and nonexposed individuals.     

Voltammetric studies of damages in DNA by mutagenic and carcinogenic alkylating chemicals

Voltammetry provides new insights into the effects exerted in vitro by methylation of native DNA. Applying single sweep voltammetry at a stationary mercury electrode the successive steps of the destabilization of alkylated DNA are investigated. The methylation of the nucleic acids is manifested by a specific electrochemical response, due to the 7‐methylguanine, a major product of the methylation of DNA. Short time effects of the methylation include the labilization of 4 to 5 base pairs per methylated guanine base. Furthermore, uncommon protonation properties of the base 7‐methylguanine‐cytosine have been detected. Long term effects of the methylation are ultimately spontaneous hydrolytic strand breaks induced by the prior depurination connected with the release of the 7‐methylguanine from the methylated DNA. A half time t_1/2 of 102 h for the depurination at 37°C has been determined. The depurination and the subsequent strand breaks alter the hydrodynamic properties of the damaged DNA, an effect which can be sensitively followed with voltammetry via the resulting changes in the diffusion coefficient of the damaged biopolymer.