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.

Measurement uncertainty arising from trueness of the analysis of two endocrine disruptors and their metabolites in environmental samples. Part I: ultrasonic extraction from diverse sediment matrices.

The validation of preconcentration strategies for the simultaneous determination of two endocrine disrupting compounds (EDCs) and their metabolites present in the aquatic environment including natural waters and freshwater sediments as well as the estimation of uncertainty arising from trueness using fully nested experimental designs are presented in a series of two papers. In this work, we present Part I of our ongoing study, the validation of an analytical method based on ultrasonic extraction of the target analytes from various freshwater sediments and the estimation of the method measurement uncertainty. The selected endocrine disruptors included two widely used herbicides, diuron (1-(3,4-dichlorophenyl)-3,3-dimethylurea) and linuron (3-(3,4-dichlorophenyl)-1-methoxy-1-methylurea) and their common degradation products namely, 3,4-dichloroaniline (3,4-DCA), 1-(3,4-dichlorophenyl) urea (DCPU) and 1-(3,4-dichlorophenyl)-3-methylurea (DCPMU). A high-performance liquid chromatography system coupled to UV-diode array detector (HPLC/UV-DAD) was used for the target analytes quantification. A fully nested experimental design was applied to study the measurement uncertainty arising from trueness by estimating proportional bias (in terms of recovery). The overall recoveries, that is, those determined by the nested experiments were in the range of 59.5-85.1%, except 3,4-DCA for which a low overall recovery of 29.0% was observed. The analytical method was shown to be linear over the studied range of concentrations (5-100 microg/kg), exhibiting satisfactory repeatability and reaching limits of detection usually in the 0.6-4.6 microg/kg range on dry sediment basis. The method used permitted the determination of the target EDCs and their metabolites in sediment samples collected from selected study stations in the region of Epirus (N.W. Greece) at the concentration levels demanded by current legislation.

Measurement uncertainty arising from trueness of the analysis of two endocrine disruptors and their metabolites in environmental samples. Part II. Solid-phase extraction from environmental natural waters.

In this work, a preconcentration method for the simultaneous determination of the endocrine disrupting chemicals (EDCs), diuron (1-(3,4-dichlorophenyl)-3,3-dimethylurea), and linuron (3-(3,4-dichlorophenyl)-1-methoxy-1-methylurea), as well as their metabolites DCPU (1-(3,4-dichlorophenyl) urea), DCPMU (1-(3,4-dichlorophenyl)-3-methylurea) and 3,4-DCA (3,4-dichloroaniline), present in natural waters was optimized and validated. Water was subjected to solid-phase extraction (SPE) and the influence of several experimental variables affecting the extraction efficiency of the target analytes was studied, including the sorbent material, elution solvents, pH and breakthrough volume, as well as some solution parameters that is, ionic strength and organic matter content. A high-performance liquid chromatography system coupled to UV-diode array detector (DAD) was used for the target analytes quantification at the optimum conditions described in Part I. The fully nested experimental design, adapted to the new experimental parameters, was used to study the measurement uncertainty arising from trueness by estimating proportional bias (in terms of recovery). The overall recoveries of the target analytes were in the range of 71.6-90.2%, except 3,4-DCA for which a low overall recovery of 51.4% was obtained. The analytical procedure was shown to be linear over the studied range of concentration (25-400 ng/l), exhibiting satisfactory repeatability and reaching limits of detection in the 1.3-11.2 ng/l range for all, quite different in nature, water types. The SPE method was further applied for the determination of the selected EDCs and their metabolites in water samples taken from selected study stations in the region of Epirus (N.W. Greece) corresponding to the sediment samples locations (Part I).

Photolytic degradation of quinalphos in natural waters and on soil matrices under simulated solar irradiation.

The photochemical persistence of quinalphos, one of the most widely used organophosphorous insecticides, was investigated in a variety of environmental matrices such as natural waters and soils of different composition. Simulated solar irradiation was obtained using a xenon arc lamp (Suntest CPS+ apparatus) giving an irradiation intensity of 750 W m(-2) equivalent to a light dose per hour of irradiation of 2,700 kJ m(-2). The phototransformation rates were determined using solid-phase microextraction (SPME) and ultrasonic extraction (USE) coupled to GC-FTD, while the identification of photoproducts was carried out by GC-MS. In water samples, the degradation kinetics followed a pseudo-first-order reaction and photolysis half-lives ranged between 11.6 and 19.0 h depending on the constitution of the irradiated media. Dissolved organic matter (DOM) has a predominant retarding effect, while nitrate ions accelerated the photodegradation kinetics. In soil samples, the degradation kinetics was monitored on 1mm soil layer prepared on glass TLC plates. The kinetic behaviour of quinalphos was complex and characterized by a double step photoreaction, fast in the first 4h of irradiation followed by a slow degradation rate up to 64 h. The photolysis half-life of quinalphos was shorter in sandy soil compared to the rest of the soil samples, varying between 16.9 and 47.5 h, and showing a strong dependence on the composition of the irradiated media. Among the transformation products formed mainly through photohydrolysis and photoisomerization processes, some photoproduct structures were proposed according to their mass spectral information.

Accumulation profiles of persistent organochlorines in liver and fat tissues of various waterbird species from Greece.

Waterbirds are particularly subject to accumulation of persistent organic pollutants (POPs) that have been shown to constitute a major hazard for this group of birds. Liver and fat tissue from ten species belonging to the orders Ciconiformes (Ardeidae, Ciconiidae, Phoenicopteridae) and Pelicaniformes (Pelecanidae, Phalacrocoracidae) were used as bioindicators in order to assess environmental pollution by POPs (HCHs, DDTs, cyclodienes, PCBs) in Greek wetlands. To our knowledge, this is the first study on POPs in livers of water birds in Greece and Eastern Mediterranean area. The DDTs consisted mainly of p,p'-DDE with percentages over 60% in the great majority of the samples. The highest summation SigmaDDT concentrations were measured in the liver and subcutaneous fat of Phoenicopterus rubber and in Ardea purpurea liver (15565, 24706 and 10406 ng g(-1) wet weight, respectively). Low concentrations of cyclodienes (Cycls) and HCHs were detected occasionally and the contamination pattern of OCPs in most species of waterbirds followed the order summation SigmaDDTs> summation SigmaCycls> summation SigmaHCHs. Individual values of total PCBs reached the levels of 4468 and 3252 ng g(-1) wet weight, for Nycticorax nycticorax and Egretta garzetta samples respectively. Some of the recorded differences in organochlorine concentrations could be due to different causes of death, with a subsequent effect on body lipid levels. Organochlorine pesticides and PCBs residues were lower than those commonly associated with mortality and reduced reproductive success in most species. However, low level exposure to these contaminants may constitute one of the many stressors that in combination could adversely affect bird populations.

Optimization of headspace solid-phase microextraction conditions for the determination of organophosphorus insecticides in natural waters.

Headspace solid-phase microextraction (HS-SPME) has been developed for the analysis of seven organophosphorus insecticides, i.e. diazinon, fenitrothion, fenthion, ethyl parathion, methyl bromophos, ethyl bromophos and ethion in natural waters. Their determination was carried out using gas chromatography with flame thermionic and mass spectrometric detection. To perform the HS-SPME, two types of fibre have been assayed and compared: polyacrylate (PA 85 microm), and polydimethylsiloxane (PDMS 100 microm). The main parameters affecting the HS-SPME process such as temperature, salt additives, memory effect, stirring rate and adsorption-time profile were studied. The method was developed using spiked natural waters such as ground, sea, river and lake water in a concentration range of 0.05-1 microg/l. The HS-SPME conditions were optimized in order to obtain the maximum sensitivity. Detection limits varied from 0.01 to 0.04 microg/l and relative standard deviations (RSD <17%) were obtained showing that the precision of the method is reliable. The method showed also good linearity for the tested concentration range with regression coefficients ranging between 0.985 and 0.999. Recoveries were in relatively high levels for all the analytes and ranged from 80 to 120%. Water samples collected from different stations along the flow of Kalamas river (NW Greece) were analyzed using the optimized conditions in order to evaluate the potential of the proposed method to the trace-level screening determination of organophosphorus insecticides. The analysis with HS-SPME has less background interference and the advantage of its non-destructive nature reveal the possibility of the repetitive use of the SPME fibre.

Photodegradation study of the antifouling booster biocide dichlofluanid in aqueous media by gas chromatographic techniques.

The aquatic photochemical behavior of the biocide dichlofluanid has been studied under natural sunlight conditions as well as under artificial solar irradiation in different types of natural waters (sea, river and lake water) as well as in distilled water. In order to examine the effect of dissolved organic matter (DOM), the photodegradation of the tested biocide was investigated also in the presence of various concentrations of humic and fulvic acids. It was found that the photodegradation proceeds via first-order reaction in all cases and that the presence of various concentrations of DOM inhibits the photolysis reaction. Kinetic experiments are monitored with GC-ECD with half-lives varied between 8 and 83 h. The major photodecomposition products identified by GC-MS were dichlorofluoromethane, aniline, and DMSA. Based on this byproduct identification a possible degradation pathway is proposed for the photolysis of dichlofluanid in aqueous media.

Determination of fungicides in natural waters using solid-phase microextraction and gas chromatography coupled with electron-capture and mass spectrometric detection.

This study develops a method for the analysis of seven fungicides in environmental waters, using solid-phase microextraction (SPME). The analyzed compounds--dicloran, chlorothalonil, vinclozolin, dichlofluanid, captan, folpet and captafol--belong to different classes of chemical compound (chloroanilines, sulphamides, phthalimides and oxazolidines) and are used mainly in agriculture and as antifouling paints. Their determination was carried out by gas chromatography with electron-capture and mass spectrometric detection. To perform SPME, four types of fibre have been assayed and compared: polyacrylate (85 microm), polydimethylsiloxane (100 and 30 microm), carbowax-divinylbenzene (CW-DVB 65 microm) and polydimethylsiloxane-divinylbenzene (65 microm). The main parameters affecting the SPME process such as pH, salt additives, methanol content, memory effect, stirring rate and adsorption-time profile were studied. The method was developed using spiked natural waters such as ground water, sea water, river water and lake water in a concentration range of 0.1-10 microg/l. Limits of detection of studied compounds were determined in the range of 1-60 ng/l, by using electron-capture and mass spectrometric detectors. The recoveries of all fungicides were in relatively high levels (70.0-124.4%) and the average R2 values of the calibration curves were above 0.990 for all the analytes. The SPME conditions were finally optimized in order to obtain the maximum sensitivity. The potential of the proposed method was realized by applying it to the trace-level screening determination of fungicides and antifouling compounds in sea water samples originating from various Greek marinas.

Monitoring of pesticide residues and their metabolites in surface and underground waters of Imathia (N. Greece) by means of solid-phase extraction disks and gas chromatography.

Seasonal variations of pesticide residues in surface waters and ground waters of the Imathia area of Central Mecedonia (N. Greece) were determined for the period from May 1996 to April 1997. The sampling cruises included eight sites in rivers Aliakmon, Loudias, Tripotamos, Arapitsa and Canal-66, seven water springs in the mountain Vermion, seven rainfall water collection stations and one hundred underground points. Solid-phase extraction disks followed by gas chromatographic techniques with flame thermionic detection, electron capture detection and mass-selective detection were used for the monitoring of various pesticides their transformation products in environmental waters. The most commonly encountered pesticides in underground waters, were alachlor, atrazine, desethylatrazine (DEA), metolachlor, molinate, propanil, simazine, carbofuran, diazinon and parathion methyl. The above compounds including propazine, trifluralin, malathion, parathion ethyl, lindane, alpha-benzene hexachloride (alpha-BHC), beta-BHC, 4,4'-DDE and heptachlor were determined in river waters. The higher concentrations in underground waters were measured during the period from May to August, 1996, following seasonal application and diminished significantly during the autumn and winter. Water pollution by triazine and chloroacetanilides was highest in the estuarine areas; showing that many of these compounds are transported significant distances from their application sites. The major inputs of atrazine, alachlor, simazine and metolachlor occurred in May and June just after their application. Atrazine, DEA, diazinon and metolachlor were also detected in spring waters at concentration levels below 0.006 microgram/l. Finally, atrazine, DEA, carbofuran, simazine, diazinon, parathion ethyl and parathion methyl were detected in rainfall water samples collected in the agricultural area of Imathia (central part of the plain).

Gas chromatographic determination of 2-hydroxy-4-methoxybenzophenone and octyldimethyl-p-aminobenzoic acid sunscreen agents in swimming pool and bathing waters by solid-phase microextraction.

A method has been developed for the trace determination of two sunscreen constituents (2-hydroxy-4-methoxybenzophenone and octyldimethyl-p-aminobenzoic acid) in water samples, which are commonly used in commercial formulations. The method employs solid-phase microextraction (SPME) and gas chromatography with flame ionization and mass spectrometric detection. The technique was developed with headspace and direct sampling in order to demonstrate the applicability of these SPME extraction modes for the identification of these two UV absorbing compounds in waters. The main parameters affecting the SPME process, such as desorption time, extraction time profile, salt additives, pH, and temperature, were investigated. The poly(dimethylsiloxane) 100-microm and polyacrylate 85-microm fiber coatings were found to be the most efficient for the extraction of these compounds from aqueous matrices. Linear calibration curves in the wide range of 10-500 microg/l were obtained for both compounds yielding typical RSD values of 5-9% for both extraction modes. The recoveries were relatively high, 82-98%, with quantitation limits below 1 microg/l. A comparison between the proposed methods and the conventional multiresidue solid-phase extraction revealed that the proposed technique(s) can be reliably used for sunscreen residue measurement in water samples with satisfactory results.

Aqueous photolysis of the sunscreen agent octyl-dimethyl-p-aminobenzoic acid. Formation of disinfection byproducts in chlorinated swimming pool water.

The photochemical behavior of the sunscreen agent octyl-dimethyl-p-aminobenzoic acid (ODPABA) was studied in different aqueous solutions and under different conditions. ODPABA photolysis was performed under laboratory conditions using a xenon light source and under natural sunlight conditions in sea, swimming pool as well as in distilled water. The influence of dissolved organic matter (DOM) on the degradation kinetics was also studied in the presence of various concentrations of humic acids (HA). The phototransformation was shown to proceed via pseudo-first-order reaction in all cases and the reaction rates followed the order: distilled water > swimming pool water > seawater, depending mainly on the presence of dissolved organic matter that retarded the photolysis reaction. Kinetic experiments were monitored with HPLC/UV-DAD and the half-lives (t 1/2) varied between 1.6 and 39 h in simulated solar irradiation and between 27 and 39 h in natural sunlight conditions. The product distribution during illumination was strongly dependent on the constitution of the irradiated media. Irradiation of the aqueous ODPABA solutions gave rise to several transformation products that were isolated by means of solid-phase extraction (SPE) and identified using GC-MS techniques. These were formed mainly through dealkylation and hydroxylation reactions and were detected in all aqueous solutions investigated. In the case of swimming pool water some additional byproducts were isolated and were tentatively identified as chlorinated intermediates, formed by the subsequent chlorination of the parent molecule as well as other intermediates.

Adsorption-desorption studies of selected herbicides in soil-Fly ash mixtures.

Fly ash and soil mixtures with a range of fly ash content from 0 to 100% were used to study the adsorption and desorption of herbicides atrazine, propazine, prometryne, propanil, and molinate in batch experiments. The isotherms shapes according to Giles classification (Giles et al., 1960) were S, L, and H as the substrate changed from sandy clay loam (SCL) to fly ash, depending on the percent of fly ash in the mixture. The adsorption isotherms fit the Freundlich equation x/m = K(f) C(1/)(n)(). The K(f) values increase with the increase of the fly ash content. The mean percent amounts of herbicides, for a range of concentration 1-20 mg L(-)(1), adsorbed on the soil were 21.9% for atrazine, 50.7% for propazine, 29.04% for prometryne, 43.14% for molinate, 31.35% for propachlor, and 46.34% for propanil. Mass balance estimations show that the adsorbed amounts of the herbicides increase along with the fly ash content in the sorbent mixture and reach the 99% in the "pure" fly ash. In contrast, the amounts desorbed with water decrease as the fly ash content increases. The n values ranged from 0.82 to 3.05 indicating that the carbon content of fly ash plays a significant role during the sorption process and an increase of heterogenity of solid substrate. The increase of the amounts desorbed with acetone indicates that the sorption of organic compounds onto fly ash is believed to occur principally via the weak induction forces of London or dispersion forces which are characteristic of the physical adsorption process. The results of this research demonstrate that the fly ash shows a significant capacity for adsorption of organic compounds from aqueous solution.

Worldwide occurrence and effects of antifouling paint booster biocides in the aquatic environment: a review.

Organic booster biocides were recently introduced as alternatives to organotin compounds in antifouling products, after restrictions imposed on the use of tributyltin (TBT) in 1987. Replacement products are generally based on copper metal oxides and organic biocides. This ban has led to an increase in alternative coating products containing the above biocides. The most commonly used biocides in antifouling paints are: Irgarol 1051, diuron, Sea-nine 211, dichlofluanid, chlorothalonil, zinc pyrithione, TCMS (2,3,3,6-tetrachloro-4-methylsulfonyl) pyridine, TCMTB [2-(thiocyanomethylthio) benzothiazole], and zineb. Since 1993, several studies have demonstrated the presence of these biocides in European coastal environment as a result of their increased use. More recently, the presence of these biocides was also revealed in waters from Japan, United States, Singapore, Australia and Bermuda. This paper reviews the currently available data on the occurrence of these biocides in the aquatic environment. Some data dealing with the environmental fate, partitioning, behaviour and risk assessment of antifouling paint booster biocides are also reported in order to discuss the detected levels of contamination.

The incidence of polychlorinated biphenyl and organochlorine pesticide residues in the eggs of the cormorant (Phalacrocorax carbo sinensis): an evaluation of the situation in four Greek wetlands of international importance.

This study contributed to identifying the current levels of organochlorine pollutants in four Greek wetlands of international importance (the Evros and Axios Deltas, and Kerkini and Prespa Lakes), using the cormorant Phalacrocorax carbo sinensis as a suitable bioindicator in a region where such information is scarce. Residue levels of eight polychlorinated biphenyl (PCB) congeners and 13 organochlorine pesticide (OC) compounds were measured in cormorant eggs. Most PCBs and OCs (except dieldrin and endrin) were found in at least some of the study areas. Median concentrations of five PCBs (IUPAC 8, 20, 52, 138, 180) and of six OCs (alpha-BHC, beta-BHC, lindane, heptachlor, 4,4'-DDE and 4,4'-DDT) differed significantly among the areas. The median totals of the PCBs were highly significant among the areas, being unexpectedly highest in Prespa Lake (68.43 ppb), despite its remoteness, and lowest in Evros Delta samples (12.17 ppb). Aldrin that was found in samples from Evros, Axios and Prespa probably accumulated in wintering grounds. In all of the areas, the relative proportions of alpha-BHC and 2,4'-DDD were the highest of all OCs. Fingerprint and cluster analyses illustrated overall differences in the PCB patterns, being greatest between the deltas than between the lakes, but, inversely, for OCs the differences were smaller in the deltas. Differences were attributed to large variations in the cormorants' diet between areas and different regimes of pollutant management in the two types of wetland. Correlations of pollutants varied considerably among areas and they were more diverse in OCs. The sum of OCs/ sum of PCBs ratio indicates agrochemical pollution in all areas. An important finding was that levels of both pollutant groups were too low to have any biological implications on the cormorants and, additionally, suggest that they have a negligible impact on the environment of the wetlands studied.

Organochlorine contaminants in eggs of the yellow-legged gull (Larus cachinnans michahellis) in the North Eastern Mediterranean: is this gull a suitable biomonitor for the region?

Levels of eight PCB congeners and thirteen organochlorine pesticides were measured in eggs sampled at four yellow-legged gull colonies from the Aegean Sea (NorthEastern Mediterranean) in 1997. There were no significant differences among colony areas in the median concentrations in any of the pollutants whereas cluster analyses did not generally reveal reasonable pollution patterns. The maximum concentrations of four congeners were found at Kinaros colony and of nine compounds were found at Lipsos colony. Fingerprints in both groups were similar in all areas. Of PCBs, congener 28, 118, 138, 180 and of pesticides beta-BHC and 2,4'-DDD were prominently dominant suggesting a particular pollution pattern in this region. Statistically significant correlations were found between most of the higher PCBs in all areas studied. The DDT metabolites correlated mostly with other OCs. We suggest that regional pollution by both groups is not adequately reflected in the eggs of this gull probably due to its extensive scavenging habits and, though information is needed from more colonies, it seems to be a poor biomonitor for organochlorines in this region.

Pesticide residues in milk and cheeses from Greece.

Thirty-eight samples of bovine milk and 28 samples of three types of cheese were collected throughout Greece during 1991 and 1992, and analyzed for 13 organochlorine insecticides, three herbicides, and one organophosphorus insecticide residues. Eleven milk samples (28.9% of analyzed samples) contained residues of one or more of the following: lindane, alpha-isomeric hexachlorocyclohexane (alpha-BHC), 1,1-bis[p-chlorophenyl]-2,2-dichloroethylene (p,p'-DDE), and methyl parathion at concentrations below the maximum permitted. Lindane was detected in five samples at concentrations of 0.8 to 7 ng/g of fat of milk, alpha-BHC in two samples at concentrations 16 and 18 ng/g, p,p'-DDE in four samples at concentrations of 14 to 32 ng/g, and methyl parathion in two samples at concentrations 43 and 280 ng/g. Nine cheese samples (32.1%) contained residues of one or more of alpha-BHC, p,p'-DDE, lindane and aldrin-dieldrin. The range of concentrations were 0.8 to 2 ng/g for lindane, 4 to 10 ng/g for alpha-BHC, 20 to 70 ng/g for p,p'-DDE and 0.2 ng/g for aldrin. All mean concentrations found were below the maximum limits permitted by the European Union.

Concentration and bioaccumulation of organochlorine pesticide residues in herons and their prey in wetlands of Thermaikos Gulf, Macedonia, Greece.

Concentrations of the principal organochlorine insecticides were determined in eggs and freshly dead chicks of the Squacco heron (Ardeola ralloides), Little Egret (Egretta garzetta) and Night Heron (Nycticorax nycticorax), as well as in frogs (Rana sp.), the main heron prey. Material was collected from the wetlands of the Thermaikos Gulf (Macedonia, northern Greece) in 1992 and 1993. Residues of the organochlorine pesticides alpha-BHC, beta-BHC, lindane, 4,4'-DDD, 4,4'-DDE, heptachlor and dieldrin were found in the eggs, chicks and prey of the herons. alpha-BHC, beta-BHC, and lindane had highest concentration in the Night Heron and lowest in the Little Egret. In all samples examined, the bioconcentration factors (BCF) of these compounds had very high values. BCF of pollutants for the eggs of the Squacco Heron were at lower levels than those of its chicks. BCF for frogs were in almost all cases lower than those for the other samples. Biomagnification factor (BMF) for 4,4'-DDE and beta-BHC had the highest values of all other compounds (except in the Night Heron). BMF for the eggs of the Squacco Heron were greater than for its chicks. Variation in the pesticide contents in the different heron species is attributed to different feeding habits; the exception being the occurrence of dieldrin in eggs only and 4,4'-DDE as a remnant of past spraying. Amounts of pesticides detected in this study are too low to affect eggshell thickness in the Squacco Heron or have other effects on the wildlife of the area.

Antifouling paint booster biocide contamination in Greek marine sediments.

Organic booster biocides were recently introduced as alternatives to organotin compounds in antifouling products, after restrictions imposed on the use of tributyltin in 1987. In this study, the concentrations of three biocides commonly used as antifoulants, Irgarol 1051 (2-methylthio-4-tertiary-butylamino-6-cyclopropylamino-s-triazine), dichlofluanid (N-dichlorofluoromethylthio-N',N'-dimethyl-N-phenyl sulphamide) and chlorothalonil (2,4,5,6-tetrachloro isophthalonitrile) were determined in sediments from ports and marinas of Greece. Piraeus (Central port, Mikrolimano and Pasalimani marinas), Thessaloniki (Central port and marina), Patras (Central port and marina), Elefsina, Igoumenitsa, Aktio and Chalkida marinas were chosen as representative study sites for comparison with previous monitoring surveys of biocides in coastal sediments from other European countries. Samples were collected at the end of one boating season (October 1999), as well before and during the 2000 boating season. All the compounds monitored were detected at most of sites and seasonal dependence of biocide concentrations were found, with maxima during the period June-September, while the winter period (December-February) lower values were encountered. The concentrations levels ranged from 3 to 690 ng/g dw (dry weight). Highest levels of the biocides were found in marinas (690, 195 and 165 ng/g dw, for Irgarol, dichlofluanid and chlorothalonil respectively) while in ports lower concentrations were observed. Antifouling paints are implicated as the likely sources of biocides since agricultural applications possibly contributed for chlorothalonil and dichlofluanid inputs in a few sampling sites.

Photodegradation of selected herbicides in various natural waters and soils under environmental conditions.

The photochemical degradation of herbicides belonging to different chemical groups has been investigated in different types of natural waters (ground, river, lake, marine) and distilled water as well as in soils with different texture and composition. Studied herbicides and chemical groups included atrazine, propazine, and prometryne (s-triazines); propachlor and propanil (acetanilides); and molinate (thiocarbamate). The degradation kinetics were monitored under natural conditions of sunlight and temperature. Photodegradation experiments were performed in May through July 1998 at low concentrations in water samples (2-10 mg/L) and soil samples (5-20 mg/kg), which are close to usual field dosage. The photodegradation rates of all studied herbicides in different natural waters followed a pseudo-first order kinetics. The half-lives of the selected herbicides varied from 26 to 73 calendar days in waters and from 12 to 40 d in soil surfaces, showing that the degradation process depends on the constitution of the irradiated media. The presence of humic substances in the lake, river, and marine water samples reduces degradation rates in comparison with the distilled and ground water. On the contrary, the degradation in soil is accelerated as the percentage of organic matter increases. Generally, the photodegradation process in soil is faster than in water. The major photodegradation products identified by using gas chromatography-mass spectrometry (GC-MS) techniques were the hydroxy and dealkylated derivatives for s-triazines, the dechlorinated and hydroxy derivative for the anilides, and the keto-derivative for the thiocarbamate, indicating a similar mode of degradation for each chemical category.

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.