Activation of persulfate by LaFe1-xCoxO3 perovskite catalysts for the degradation of phenolics: Effect of synthetic method and metal substitution.

The presence of resistant organic pollutants in environmental substrates requires the development and finding of novel decontamination methods. Advanced oxidation processes are among the most effective methods used for degradation of these pollutants through their oxidation and degradation into non-toxic and harmless, for the environment, final products. Ιn this research, a series of perovskites of ABO3-type, with La and Fe and/or Co in A and B positions respectively, LaFe1-xCoxO3 (x = 0, 0.25, 0.5, 0.75, 1), were synthesized with two different methods, a soft template method using anionic surfactant and by glycine combustion method and studied for their catalytic activity towards the degradation of phenolic compounds, a major class of environmental pollutants, through persulfate activation. The catalytic activity depended both by the B metal ion of perovskites and their ratio as well as by the synthesis method. LaCoO3 prepared with the anionic surfactant method, showed the highest catalytic activity with a rate constant of 0.024 min-1. Furthermore, the synthesis method also influenced the stability of perovskites as metal leaching studies showed that perovskites synthesized with the anionic surfactant showed greater stability. Quenching experiments were also used in order to shed light on the catalytic activation mechanism of persulfate for the degradation of phenolics. Overall, the results showed that the synthesis method can significantly affect the catalytic activity of the materials and their stability since the same materials synthesized with different methods show significantly different catalytic properties.

Comparative evaluation of river chemical status based on WFD methodology and CCME water quality index.

The Water Framework Directive (WFD) methodology, proposed by the Ministry of Environment and Energy of Greece (WFD-MEEG), and the Canadian Council of Ministers of Environment Water Quality Index (CCME-WQI) are comparatively applied to evaluate the chemical status of a major transboundary river. Water quality parameters were monitored at 11 sites along the main stream of the river and its main tributaries, and at five sites in the reservoirs, on a monthly frequency, in the period from May 2008 to May 2009. Water temperature (T), dissolved oxygen (DO), pH, and electrical conductivity (EC) were measured in-situ, while water samples were collected for the determination of total suspended solids (TSS), biochemical oxygen demand (BOD), chemical oxygen demand (COD), nitrite-, nitrate- and ammonium-nitrogen, total Kjeldahl nitrogen (TKN), ortho-phosphates (OP), total phosphorus (TP), and chlorophyll-a (Chl-a). The water samples were also analyzed for the determination of seven heavy metals (i.e., Cd, Pb, Hg, Ni, Cr, Cu, Zn) and 33 priority substances, as listed in Annex II of EU Directive 2008/105/EC. The results showed that the physicochemical parameters (i.e., T, DO, pH, EC, inorganic nitrogen, TKN, OP, TP, TSS, and Chl-a) were within the natural range. The mean concentration of the measured heavy metals did not exceed the limits set by WHO (2003, 2017) for drinking water. Regarding the priority substances, some of them (i.e., anthracene, fluoranthene, and polyaromatic hydrocarbons) were measured in various stations at higher concentrations than the Annual Average Environmental Quality Standards (AA-EQS). Based on the WFD-MEEG methodology, the river water was in the 'good' quality class, while according to CCME-WQI the river quality ranged from 'marginal' to 'good' category. It seems that CCME-WQI is stricter than WFD-MEEG but could be a WQI appropriate for use.

Photo-Fenton and Fenton-like processes for the treatment of the antineoplastic drug 5-fluorouracil under simulated solar radiation.

In the present study, photo-Fenton and Fenton-like processes were investigated for the degradation and mineralization of the antineoplastic drug 5-fluorouracil (5-FU). For the optimization of photo-Fenton treatment under simulated solar light (SSL) radiation, the effects of several operating parameters (i.e., 5-FU concentration, Fe3+, and oxidant concentration) on the treatment efficiency were studied. According to the results, SSL/[Fe(C2Ο4)3]3-/Η2Ο2 process was the most efficient, since faster degradation of 5-FU and higher mineralization percentages were achieved. All the applied processes followed quite similar transformation routes which include defluorination-hydroxylation as well as pyrimidine ring opening, as demonstrated by the transformation products identified by high resolution mass spectrometry analysis. The toxicity of the treated solutions was evaluated using the Microtox assay. In general, low toxicity was recorded for the initial solution and the solution at the end of the photocatalytic treatment, while an increase in the overall toxicity was observed only at the first stages of SSL/Fe3+/Η2Ο2 and SSL/Fe3+/S2O82- processes.

Photocatalytical removal of fluorouracil using TiO2-P25 and N/S doped TiO2 catalysts: A kinetic and mechanistic study.

In the present study, the photocatalytic activity of TiO2-based photocatalysts toward degradation and mineralization of the anti-cancer drug 5-fluorouracil (5-FU) in aqueous phase was investigated under simulated solar and visible irradiation. Commercial TiO2 (P25) and N/S-doped TiO2 catalysts synthesized by a simple sol-gel method were used as photocatalysts. TiO2 P-25 was found to be the most photoactive catalyst for the removal of 5-FU, under simulated solar irradiation. Among N/S-doped TiO2 catalysts, the one with molar Ti:N/S ratio equal to 0.5 was the most efficient under simulated solar irradiation. In contrast, under visible irradiation the catalyst with equimolar Ti:N/S ratio showed the highest performance for the removal of 5-FU. Scavenging experiments revealed that HO radicals and h+ were the major reactive species mediating photocatalytic degradation of 5-FU using TiO2 P-25 and N/S-doped TiO2 catalysts, under simulated solar irradiation. On the other hand, the essential contribution of 1O2 and O2- in the degradation of 5-FU under visible light was proved. The transformation products (TPs) of 5-FU, were identified by LC-MS-TOF suggesting that defluorination followed by hydroxylation and oxidation are the main transformation pathways, under all the studied photocatalytic systems.

Photocatalytic reduction of Cr(VI) by char/TiO2 composite photocatalyst: optimization and modeling using the response surface methodology (RSM).

The photocatalytic reduction of Cr(VI) using pyrolytic char/TiO2 (PC/TiO2) composite catalyst under simulated solar irradiation was studied. Response surface methodology (RSM) and experimental design were used for modeling the removal kinetics and for the optimization of operational parameters. RSM was developed by considering a central composite design with four input variable, i.e. catalyst concentration, initial concentration of Cr(VI), pH, and % (v/v) methanol concentration for assessing individual and interactive effects. A quadratic model was established as a functional relationship between four independent variables and the removal efficiency of Cr(VI). It was found that all selected variables have significant effect on Cr(VI) removal efficiency; however, the pH, the % concentration of methanol, and their interaction exhibited the major effects. Within the studied experimental ranges, the optimum conditions for maximum Cr(VI) removal efficiency (72.1 %) after 60 min of photocatalytic treatment were: catalyst concentration 55 mg L-1, Cr(VI) concentration 20 mg L-1, pH 4, and 5 % (v/v) methanol concentration. Under optimum conditions, Cr(VI) reductive removal followed pseudo-first-order kinetics, and nearly complete removal took place within 90 min. The results revealed the feasibility and the effectiveness of PC/TiO2 as photocatalyst in reduction reactions due to their ability of e--h+ pair separation increasing the transfer of the photogenerated e- to the catalyst's surface and thus the reduction of Cr(VI).

Degradation of venlafaxine using TiO2/UV process: Kinetic studies, RSM optimization, identification of transformation products and toxicity evaluation.

The photochemical degradation of the antidepressant drug venlafaxine (VNF) by UV/TiO2 process was investigated in the present study. Prescreening experiments were conducted to study the effects of main parameters affecting the photocatalytic process. In addition, the effects and interactions of most influenced parameters were evaluated and optimized by using a central composite design model and a response surface methodology. Results indicated that VNF was quickly removed in all the irradiation experiments and its degradation was mainly affected by the studied variables (catalyst dose, initial VNF concentration and pH), as well as their interaction effects. Parallel to kinetic studies, the transformation products (TPs) generated during the treatment was investigated using LC coupled to low and high resolution mass spectrometry. Based on identification of the main TPs, tentative transformation pathways were proposed, including hydroxylation, demethylation and dehydration as major transformation routes. Τhe potential risk of VNF and its TPs to aqueous organisms was also investigated using Microtox bioassay before and during the processes. The obtained results showed an increment in the acute toxicity in the first stages and a continuously decreasing after then to very low values reached within 240min of the photocatalytic treatment, demonstrating that UV/TiO2 can lead to the elimination of parent compound and the detoxification of the solution.

Recycled-tire pyrolytic carbon made functional: A high-arsenite [As(III)] uptake material PyrC350®.

A novel material, PyrC350®, has been developed from pyrolytic-tire char (PyrC), as an efficient low-cost Arsenite [As(III)] adsorbent from water. PyrC350® achieves 31mgg-1 As(III) uptake, that remains unaltered at pH=4-8.5. A theoretical Surface Complexation Model has been developed that explains the adsorption mechanism, showing that in situ formed Fe3C, ZnS particles act cooperatively with the carbon matrix for As(III) adsorption. Addressing the key-issue of cost-effectiveness, we provide a comparison of As(III)-uptake effectiveness in conjunction with a cost analysis, showing that PyrC350® stands in the top of [effectiveness/cost] vs. existing carbon-based, low-cost materials.

Photocatalytic degradation kinetics, mechanism and ecotoxicity assessment of tramadol metabolites in aqueous TiO2 suspensions.

This study investigated for the first time the photocatalytic degradation of three well-known transformation products (TPs) of pharmaceutical Tramadol, N-desmethyl-(N-DES), N,N-bidesmethyl (N,N-Bi-DES) and N-oxide-tramadol (N-OX-TRA) in two different aquatic matrices, ultrapure water and secondary treated wastewater, with high (10 mg L(-1)) and low (50 µg L(-1)) initial concentrations, respectively. Total disappearance of the parent compounds was attained in all experiments. For initial concentration of 10 mg L(-1), the target compounds were degraded within 30-40 min and a mineralization degree of more than 80% was achieved after 240 min of irradiation, while the contained organic nitrogen was released mainly as NH4(+) for N-DES, N,N-Bi-DES and NO3(-) for N-OX-TRA. The degradation rates of all the studied compounds were considerably decreased in the wastewater due to the presence of inorganic and organic constituents typically found in effluents and environmental matrices which may act as scavengers of the HO(•). The effect of pH (4, 6.7, 10) in the degradation rates was studied and for N-DES-TRA and N,N-Bi-DES-TRA, the optimum pH value was 6.7. In contrast, N-OX-TRA showed an increasing trend in the photocatalytic degradation kinetic in alkaline solutions (pH 10). The major transformation products were identified by high resolution accurate mass spectrometry coupled with liquid chromatography (HR-LC-MS). Scavenging experiments indicated for all studied compounds the important role of HO(•) in the photocatalytic degradation pathways that included mainly hydroxylation and further oxidation of the parent compounds. In addition, Microtox bioassay (Vibrio fischeri) was employed for evaluating the ecotoxicity of photocatalytically treated solutions. Results clearly demonstrate the progressive decrease of the toxicity and the efficiency of the photocatalytic process in the detoxification of the irradiated solutions.

Environmental fate of the insecticide cypermethrin applied as microgranular and emulsifiable concentrate formulations in sunflower cultivated field plots.

A field dissipation and transport study of the insecticide cypermethrin applied as microgranular (MG) and emulsifiable concentrate (EC) formulations has been conducted in field sunflower cultivations and bare soil plots with two different slopes (1% and 5%). The dissipation of insecticide in soil (on planting rows) was monitored for a period of 193 days. Cypermethrin residual concentrations in the upper soil layer (0-10 cm), 2 days after soil application (DASA), ranged from 0.53 to 0.73 µg g(- 1) when the maximum values were observed 7 DASA, ranged from 1.06 to 1.23 µg g(-1). The dissipation rate was better described by first-order kinetics. The average half-life in cultivated (tilled and planted) plots was 23.07 and 24.24 days for soil slopes 5% and 1%, respectively. In uncultivated (tilled but not planted) plots the respective values were 22.01 and 22.37 days. The insecticide was found below the 10 cm soil layer occasionally in few samples at low concentrations (< 0.02 µg g(- 1)). In runoff water it was detected once (7 days after foliar application, at levels below LOQ), when in sediment it was detectable for seven samplings. The maximum values were observed 7 days after foliar application, when they reached 0.097 and 0.143 µg g(-1) in cultivated plots with soil slopes 1% and 5%; and 0.394 and 0.500 µg g(-1) in uncultivated plots, respectively. The amount of cypermethrin which was transferred by the sediment remained at low levels (less than 0.01% of the totally applied active ingredient), even in plots with 5% inclination. The insecticide was detected in leaves and stems of the sunflower plants after the foliar application up to the day of harvest. On the contrary, in roots it was detectable during the whole cultivation period. No residues were detected in flowers or seeds.

Photocatalytic degradation of pentachlorophenol by visible light Ν-F-TiO2 in the presence of oxalate ions: optimization, modeling, and scavenging studies.

The efficiency of heterogeneous photocatalysis using N-F-TiO2 as photocatalyst to degrade a priority pollutant, pentachlorophenol (PCP), in the presence of oxalates (OA) was investigated in detail. Response surface methodology was used to optimize the effect of three variables (catalyst concentration, OA/PCP ratio, and pH) on the photocatalytic degradation of pentachlorophenol. A quadratic model was established as a functional relationship between three independent variables and the degradation efficiency of PCP. The results of model fitting and statistical analysis demonstrated that the pH played a key role in the degradation of PCP. Within the studied experimental ranges, the optimum conditions for maximum PCP degradation efficiency (97.5 %) were: catalyst concentration 600 mg L(-1), OA/PCP ratio 2, and pH 10. The contribution of HO(·), O2 (·-), and e(-) produced during the photocatalytic treatment was investigated with the addition of scavengers. The photocatalytic degradation was essentially proceeded through an oxidative mechanism at both acid and alkaline pH values by HO(.) and O2 (·-) radicals attack. It was found that O2 (·-) were the major reactive species involved in PCP degradation in pH 4 and HO(·) in pH 10.

Photocatalytic degradation of pentachlorophenol by N-F-TiO2: identification of intermediates, mechanism involved, genotoxicity and ecotoxicity evaluation.

In the present study the photocatalytic degradation of a toxic priority pollutant, PCP, in the presence of N-F codoped TiO2 was explicitly investigated. The efficiency of the process to remove PCP was monitored for the first time through combined evaluation of several aspects: the kinetic study of the PCP degradation, identification of transformation products by a combination of mass spectrometric techniques (HR-LC-MS and GC-MS), assessment of total mineralization during the process, and evaluation of the genotoxicity and ecotoxicity of the initial and treated solutions applying the cytokinesis block micronucleus (CBMN) assay and Microtox assay, respectively. On the basis of identified products, a proposed degradation pathway is presented, involving mainly oxidative dechlorination reactions. Genotoxicity and ecotoxicity studies clearly demonstrated the efficiency of the photocatalytic process in the detoxification as well as in the elimination of genotoxicity and cytotoxicity of the irradiated solutions.

A review on advanced oxidation processes for the removal of taste and odor compounds from aqueous media.

In view of the global concern about the occurrence of taste and odor (T&O) compounds in waters for drinking water supply and the necessity for the development of more innovative and efficient technologies for water treatment and depuration, the focus of this study is to provide a state of the art overview on current knowledge for the application of advanced oxidation technologies for the treatment of T&O compounds in aquatic media. The most representative and newly emerging compounds belonging to the major groups of T&O compounds, such as geosmin, methylisoborneol, benzothiazoles, mercaptans and sulfides as well as aromatic and other miscellaneous T&O compounds, are included in the systematic overview. The current data has been compiled and extensively discussed in terms of the degree of degradation, reaction kinetics, effect of operational parameters and water quality, identity of intermediate and final products and possible transformation pathways.

Persistence of oxyfluorfen in soil, runoff water, sediment and plants of a sunflower cultivation.

A field dissipation and transport study of oxyfluorfen in a sunflower cultivation under Mediterranean conditions have been conducted in silty clay plots (cultivated and uncultivated) with two surface slopes (1% and 5%). The soil dissipation and transport of oxyfluorfen in runoff water and sediment, as well as the uptake by sunflower plants, were investigated over a period of 191 days. Among different kinetic models assayed, soil dissipation rate of oxyfluorfen was better described by first-order kinetics. The average half-life was 45 and 45.5 days in cultivated plots with soil slopes 5% and 1% respectively, and 50.9 and 52.9 days in uncultivated plots with soil slopes 5% and 1%. The herbicide was detected below the 10 cm soil layer 45 days after application (DAA). Limited amounts of oxyfluorfen were moved with runoff water and the cumulative losses from tilled and untilled plots with slope 5% were estimated at 0.007% and 0.005% of the initial applied active ingredient, while for the plots with slope of 1%, the respective values were 0.002% and 0.001%. The maximum concentration of oxyfluorfen in sediment ranged from 1.46 µg g(-1) in cultivated plot with soil slope 1% to 2.33 µg g(-1) in uncultivated plot with soil slope 5%. The cumulative losses from tilled and untilled plots with slope 5% were estimated at 0.217% and 0.170% while for the plots with slope of 1%, the respective values were 0.055% and 0.025%. Oxyfluorfen was detected in sunflower plants until the day of harvest; maximum concentrations in stems and leaves (0.042 µg g(-1)) were observed 33 DAA and in roots (0.025 µg g(-1)) 36 DAA. In conclusion, oxyfluorfen hardly moves into silty clay soil and exhibited low run-off potential so it represents a low risk herbicide for the contamination of ground and adjacent water resources.

Photocatalytic degradation of the fungicide Fenhexamid in aqueous TiO(2) suspensions: identification of intermediates products and reaction pathways.

Liquid-chromatography interfaced with time-of-flight mass spectrometry (LC-TOF/MS) was used to separate and characterize the transformation products arising from TiO(2)-photocatalytic degradation of the fungicide Fenhexamid (FEX) in aqueous solution under simulated solar irradiation. Prior to identification, irradiated solutions of FEX (10mgL(-1)) were concentrated by solid-phase extraction. Assignments of the mass spectra ions were aided by elemental composition calculations, comparison of structural analogues and available literature, and acquired knowledge regarding mass spectrometry of related heterocyclic compounds. The primary transformation intermediates identified were hydroxyl and/or keto-derivatives. Several positional isomers are typically produced as a consequence of the non-selectivity of the ()OH radical attack. Moreover, products resulted from the cleavage of the amide and NH-dichlorophenol bonds were formed. Finally, cyclic - benzo[d]oxazole intermediates are also formed through an intramolecular photocyclization process and cleavage of halogen - carbon bond. In the case of the hydroxy and/or keto-derivatives, the generic fragmentation scheme obtained from the interpretation of the ESI-TOF-MS data cannot be diagnostic to precisely localize the position of the entering substituent on the FEX molecule, and thus to characterize all its possible oxygenated derivatives by assigning a plausible structure with confidence. On the basis of identified products different pathways of photocatalytic degradation of FEX were proposed and discussed.

Pesticide inputs from the sewage treatment plant of Agrinio to River Acheloos, western Greece: occurrence and removal.

This work reports the occurrence and the removal of a wide spectrum of pesticides in municipal wastewaters from the Agrinio region, Greece. Analytical determination was carried out by means of solid-phase extraction followed by gas chromatography equipped with flame thermionic and mass spectrometric detection. The herbicides atrazine, alachlor, isoproturon, and s-metolachlor and the insecticides diazinon, methidathion, fenthion and chlorpyriphos, were more frequently detected in influent and effluent samples while they were also detected in river samples. Isoproturon and diazinon showed the highest concentrations in influent samples that reached concentrations up to 2,328 and 1,486 ng L(-1), respectively. Secondary treatment and cumulative removal rates for herbicides and insecticides ranged between 23-91%, 21->99% and 36->99%, 38->99%, respectively. The data demonstrate that there are significant levels of pesticides entering river waterways.

Occurrence and removal of fungicides in municipal sewage treatment plant.

This work reports the occurrence and the removal of widely used fungicides, in municipal sewage treatment plant receiving combined sewage discharges and operating with primary (mechanical), secondary (activated sludge) and tertiary (sand filtration and chlorination) treatments that are commonly applied in Greece. Target analytes included compounds belonging to triazoles and anilino-pyrimidines. Analytical determination in wastewaters and river water samples was carried out by means of solid-phase extraction followed by gas chromatography equipped with flame thermionic and mass spectrometric detection. The fungicides tebuconazole and cyproconazole were more frequently detected in influent and effluent samples at concentrations up to 1893 and 1735 ng L(-1), respectively. Effluent concentrations were below 691.1 ng L(-1) recorded for tebuconazole. With the exception of triadimefon, all the azole fungicides and pyrimethanil showed relatively low removal efficiencies after secondary and tertiary treatments. Mean removal rates of the fungicides after secondary treatment ranged between 31% for pyrimethanil and 65% for triadimefon. Mean overall removal efficiencies after tertiary treatment ranged between 46% for pyrimethanil and 93% for triadimefon. The findings demonstrate that significant levels of fungicides enter river waterways and that only some of these compounds are being reduced in low levels by municipal wastewater treatment processes.

Organophosphorus pesticide residues in Greek virgin olive oil: levels, dietary intake and risk assessment.

The occurrence of organophosphorus pesticide (OPs) and their metabolite residues was investigated in 167 samples of Greek virgin olive oil during a 2-year (2004-2005) sampling campaign. A total of 30.5% of samples contained detectable residues, although only one sample contained dimethoate residues above the maximum residue limit. Among the seven detected OPs, fenthion and fenthion sulfoxide residues were detected in 10.8 and 14.4% of the samples, respectively, at levels of 0.003-0.61 mg kg(-1). Dimethoate was detected in 10.2% of the samples at 0.003-0.057 mg kg(-1). The acute dietary risk assessment was undertaken by determining the national estimated short-term intake (NESTI); for chronic dietary risk assessment, the national theoretical maximum daily intake (NTMDI) and national estimated daily intake (NEDI) were calculated. The estimated intakes (NESTI and NEDI) of each pesticide were <7 and <0.86% of the corresponding acute reference doses (ARfDs) and acceptable daily intakes (ADIs), respectively. A cumulative risk assessment was performed using the hazard index (HI) and toxicity equivalence factor (TEF), taking into account that OPs share the same toxicological mechanism. The determined HI and TEF values were found to represent only a small portion of the respective ADIs or ARfDs. These results indicate that there is neither acute nor chronic risk for the Greek population through olive oil consumption.

Identification of photocatalytic degradation products of bezafibrate in TiO(2) aqueous suspensions by liquid and gas chromatography.

In the present study the photocatalytic degradation of bezafibrate (BZF), a lipid regulator agent, has been investigated using TiO(2) suspensions and simulated solar light. The study focus on the identification of degradation products (DPs) using powerful analytical techniques such as liquid chromatography time of flight mass spectrometry (LC-TOF-MS), gas chromatography mass spectrometry (GC-MS), and high-performance liquid chromatography with diode-array detection (HPLC-DAD). Each technique provided complementary information that enabled the identification of 21 DPs. Accurate mass measurements obtained by LC-TOF-MS provided the elucidation of 17 DPs. Mass errors lower than 2mDa, allowed the assignment of empirical formula for the mayor DPs to be determined confidently. Three DPs were identified by GC-MS through the structural information provided by full scan mass spectra obtained by electron impact (EI) ionization and two more by HPLC-DAD by comparing the retention times (t(R)) and the UV spectra of the unknown DPs with those of commercial standards. Based on this by-product identification a possible multi-step degradation scheme was proposed. The pathways include single or multiple hydroxylation of BZF with subsequent phenoxy ring opening and the cleavage of the amide and ether bonds.

PCB levels and accumulation patterns in waterbird eggs and in their prey at Lake Kerkini, a north-eastern Mediterranean wetland of international importance.

Seven "target" PCB levels were determined and compared in waterbird eggs, in their prey, and in water at Lake Kerkini, northern Greece, to investigate PCB bioaccumulation patterns and to define the best bioindicator of target PCBs for this area. PCBs were analysed from eggs of Phalacrocorax carbo, Podiceps cristatus, Ardea cinerea, Egretta garzetta, and Nycticorax nycticorax and from prey types Alburnus alburnus, Rutilus rutilus, Lepomis gibbosus. Carassius auratus, and Rana sp. PCBs analysed were detected in all bird eggs, prey, and water but contamination patterns differed among these sample types. The lipid-corrected geometric means of the congeners analysed were significantly different among most bird species and among some prey species. PCB congeners 118, 138, 153, and 180 accounted for around 80% of the total PCB contamination in bird egg samples. Percent congener concentrations of high-chlorinated PCBs tended to increase from water through prey to most bird egg samples whereas the low chlorinated PCBs (28 and 52) decreased. Bioaccumulation factors (BAFs) also exhibited an increasing trend for higher chlorinated PCBs from prey types to bird eggs. The greatest BAFs of six of the congeners were shared between Phalacrocorax carbo and Ardea cinerea. Among prey, the BAFs of four PCBs were highest in Lepomis gibbosus. Biomagnification factors varied between 1.01 and 39.57. In contrast to low chlorinated PCBs, high chlorinated congeners biomagnified considerably through fish prey. The highest biomagnification took place in Phalacrocorax carbo. No relationship was found between the lipid content of samples and BAFs of PCBs probably due to biotransformation differences of the congeners in the biota sampled. Due to the greatest PCB concentrations especially of the higher chlorinated PCBs in the eggs of Phalacrocorax carbo and its considerable bioaccumulation tendencies, it is proposed as the best PCB biomonitor of target PCBs at Lake Kerkini. Lepomis gibbosus had the highest concentrations of most congeners and exhibited the greatest bioaccumulative properties among prey and can be used as an alternative biomonitor.

Oxidation of two organophosphorous insecticides by the photo-assisted Fenton reaction.

The photocatalytic degradation of two selected insecticides (dimethoate and methyl parathion) has been studied using the photo-assisted Fenton reaction. The degradation kinetics were studied under different conditions such as iron's and oxidant's concentration, temperature and inorganic ions. The degradation rates proved to be strongly influenced by these parameters. The replacement of hydrogen peroxide with peroxydisulfate was also tested in a photo-Fenton-like reaction. This system achieved high degradation rates of the selected compounds. Intermediate products formed during photocatalytic treatment were identified by means of solid-phase extraction (SPE) coupled to gas chromatography-mass spectroscopy techniques (GC-MS). Eight possible by-products were identified for parathion methyl and three for dimethoate formed through mainly oxidation and dealkylation reactions. Mineralization studies showed also that the photo-Fenton and the photo-Fenton-like systems are able to achieve mineralization of the insecticides. However, complete detoxification is achieved only in the presence of the photo-Fenton reagent.