Dimitra Hela

Environmental monitoring and ecological risk assessment for pesticide contamination and effects in Lake Pamvotis, northwestern Greece

Monitoring of pesticide residues in water and sediments was conducted as a basis for subsequent ecotoxicological risk assessment for the shallow eutrophic Lake Pamvotis, northwestern Greece. During a one-year study period, atrazine, desethylatrazine (DEA), simazine, diazinon, malathion, oxamyl, carbofuran, and ethion were detected in water and atrazine, desethylatrazine, diazinon, and s-ethyl dipropylthiocarbamate (EPTC) in sediments, all at ppb concentration level. Temporal variation in pesticide concentrations was observed. Highest residue levels for most pesticides in both water and sediment matrices occurred in the May to July period with the exception of atrazine and DEA, which show highest levels in water during the September to November period. The ecological risk associated with pesticide contamination was assessed using two different methods: The toxic unit method, which provides a first indication of the relative contribution of detected pesticides to the total toxicity and a probabilistic approach, and the inverse method of Van Straalen and Denneman, which is used to quantify the ecological risk. The maximum percentage of the ecological risk was 10.3 and 51.8% for water and 17.2 and 70.6% for sediment, based on acute and chronic level, respectively. These results show that pesticides exert a significant pressure on the aquatic system of Lake Pamvotis, especially for the chronic-effect level. Simple quotient methods should be coupled with higher-tier risk assessment, especially if restoration activities on lake ecosystems are to be undertaken for sustainable development.

Multi-residue pesticide analysis in environmental water samples using solid-phase extraction discs and gas chromatography with flame thermionic and mass-selective detection

Abstract A multi-residue analysis for 25 pesticides was developed as a rapid screening method for organic contaminants in river, lake and sea water samples. Gas chromatography with flame thermionic detection (GC-FTD) and mass selective detection (GC-MSD) using two different capillary columns, DB-1 and HP-5, was employed for the identification of 25 selected pesticides belonging to triazines, organophosphorus compounds and substituted ureas, carbamates, anilides, anilines and amides. The extraction of various natural waters spiked with pesticide mixtures was affected with C18 Empore solid-phase extraction discs and filter-aid glass beads. The triazine compounds (atrazine, simazine, propazine, prometryne and cyanazine) were recovered from distilled and underground water samples at relative high levels (73.5–105%) compared with the river waters (39.9–80.5%), lake water (54.6–81.8%) and marine water (38.6–79.9%). The organophosphorus compounds studied (monocrotophos, terbufos, diazinon, methyl parathion, ethyl parathion, malathion and ethion) were also recovered from distilled and underground water samples at relatively high levels (62.4–118%) compared with river waters (27.3–98.9%), lake water (41.0–85.2%) and marine water (33.4–81.3%). The substituted ureas (monuron, diuron and linuron), substituted anilines and anilides (trifluralin, propanil, propachlor and alachor), carbamates (EPTC and carbofuran) and other compounds (molinate, picloram, captan and MCPA isooctyl ester) were recovered at the same level as triazines. Confirmation of pesticide identity was performed by using GC-MS in the selected-ion monitoring mode.

Application of solid-phase microextraction in the monitoring of priority pesticides in the Kalamas River (N.W. Greece)

A solid-phase microextraction (SPME) method was applied to an extended monitoring survey of priority pesticides for the European Union for a period of 12 months in water of the Kalamas River (Epirus region of northwestern Greece) in order to determine their concentrations and seasonal variations. Polydimethylsiloxane-coated fiber (100 microm) was used. The samples were screened using gas chromatography with flame thermionic detection. Detection was confirmed by gas chromatographymass spectroscopy. The most frequently detected pesticides were some of the more commonly used herbicides, such as S-ethyl-N,N-di-n-propylthiol carbamate (EPTC), trifluralin, atrazine, deethylatrazine, terbuthylazine and alachlor, and insecticides, such as carbofuran, diazinon, disulfoton, parathion methyl, parathion ethyl, fenthion and ethion. Concentrations of individual compounds ranged from 0.020 to 0.3 microg/L. Greater pesticide concentrations occurred during the seasons of application. A comparison with a well-established solid-phase extraction (C18 disks) procedure was performed for samples of high-season application (May-September) in order to confirm the effectiveness of the SPME technique. The results demonstrate the suitability of the SPME method for routine screening multiresidue analysis in natural waters.

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.

Seasonal water quality of shallow and eutrophic Lake Pamvotis, Greece: implications for restoration

Lake Pamvotis is a moderately sized (22 km2) shallow (zavg=4 m) lake with a polymictic stratification regime located in northwest Greece. The lake has undergone cultural eutrophication over the past 40 years and is currently eutrophic (annual averages of FRP=0.07 mg P l-1, TP=0.11 mg P l-1, NH4+=0.25 mg N l-1, NO3−=0.56 mg N l-1). FRP and NH4+ levels are correlated to external loading from streams during the winter and spring, and to internal loading during multi-day periods of summer stratification. Algal blooms occurred in summer (July–August green algae, August–September blue-green algae), autumn (October blue-green algae and diatoms), and winter (February diatoms), but not in the spring (March–June). The phytoplankton underwent brief periods of N- and P-limitation, though persistent low transparency (secchi depth of 60–80 cm) also suggests periods of light limitation. Rotifers counts were highest from mid-summer to early autumn whereas copepods were high in the spring and cladocerans were low in the summer. Removal of industrial and sewage point sources a decade ago resulted in a decrease in FRP. A phosphorus mass balance identified further reductions in external loading from the predominately agricultural catchment will decrease FRP levels further. The commercial fishery and lake hatchery also provides opportunities to control algal biomass through biomanipulation measures.

Transportation of pesticides in estuaries of Louros and Arachthos rivers (Amvrakikos Gulf, N. W. Greece)

Abstract Water and sediment samples from seven stations in estuaries of the Louros and Arachthos rivers as well as in the wetlands of the Amvrakikos Gulf were collected for a period from March 1992 to February 1993. The herbicides atrazine, simazine, alachlor, metolachlor, trifluralin and diuron and the organochlorine insecticides α-BHC, lindane and 4,4′-DDE were detected in riverine estuaries and wetlands. The highest concentrations of herbicides, atrazine, simazine, alachlor, metolachlor, diuron and trifluralin in water samples were detected during the period from March to August. The same herbicides and organochlorine insecticides as well as the β-BHC and 4,4′-DDT were found in significant amounts in sediments of river estuaries and wetlands of the Amvrakikos Gulf. The percentage of total amount of detected pesticides released through the rivers into Amvrakikos Gulf are estimated as 3.1% for atrazine, 1.7% for simazine, 1.9% for diuron, 0.3% for metolachlor, 0.9% for alachlor, 0.3% for lindane and 0.6% for trifluralin.

Determination and risk assessment of pesticide residues in lake Amvrakia (W. Greece) after agricultural land use changes in the lake's drainage basin

A monitoring study of pesticides belonging to different chemical families was carried out in Amvrakia lake (West Greece) waters after land use changes in the lakes basin. Based on land-use patterns, nine sampling points were selected. Pesticides were extracted by solid phase extraction (SPE) using Oasis HLB cartridges and analysed by gas chromatographic techniques with flame thermionic and mass-spectra detection. Pesticides detected during the monitoring survey include eight herbicides (alachlor, atrazine, s-metolachlor, pendimethalin, prometryne, propachlor, simazine, trifluralin) and one metabolite (deethyl atrazine) with concentration levels up to 807 ng L−1 (recorded for alachlor), eight insecticides (azinphos methyl, chlorpyrifos, chlorpyrifos methyl, diazinon, dimethoate, fenitrothion, malathion, methidathion) with concentration levels up to 490 ng L−1 (recorded for azinphos methyl) and six fungicides (benalaxyl, cyproconazole, fenarimol, pyrimethanil, triadimefon, triadimenol) with concentration levels up to 408 ng L−1 (recorded for pyrimethanil). More frequently detected pesticides were atrazine, deethyl atrazine, alachlor, azinphos methyl, chlorpyrifos methyl, diazinon and pyrimethanil. The higher concentrations were measured during spring-early summer period, following seasonal application of pesticides and diminished significantly during winter. Littoral sampling stations presented higher pesticide concentration levels and more frequent detection. Aquatic risk assessment was based on the Risk Quotient (RQ = MEC/PNEC) deterministic method regarding three trophic levels: algae, aquatic invertebrates and fish. Non-acceptable risk for 10 compounds was observed when maximum concentrations were used. Compliance to EC environmental quality standards is also discussed.

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.

Gas chromatographic–mass spectrometric methodology using solid-phase microextraction for the multiresidue determination of pesticides in surface waters

Solid-phase microextraction (SPME) coupled with gas chromatography–mass spectrometry (GC–MS) and selected ion monitoring (SIM) was used for the analytical determination of priority pesticide residues. Fibers coated with a 65-µm film thickness of polydimethylsiloxane divinylbenzene (PDMS-DVB) were used to extract 31 pesticides of different chemical groups. The quality parameters of the method demonstrated a good precision with detection limits of 1–56 ng/L. Linearity was controlled in the range of 0.1–50 µg/L. The proposed method was applied for the trace-level determination of the target pesticides in surface water samples including three rivers and one lake at the Epirus region (north-west Greece) for a period of one year. The results demonstrate the suitability of the SPME–GC–MS approach for the analysis of multi-residue pesticides in environmental water samples.

Pesticide concentrations in louros river and their fluxes into the marine environment

Seasonal variations and riverine input of pesticide residues to the coastal zone were determined in Louros River for the period of 1995 and 1996. The sampling sites for the determination of fluxes were located at the main river flow and its estuary at the boundary between freshwater and the brackish zone. Solid-phase extraction (SPE) disks followed by gas chromatographic techniques (GC with MSD and FTD) were used for the monitoring of various pesticides and metabolites in river waters from the sources to the estuary. The inputs of the five major herbicides, atrazine, simazine, alachlor, metolachlor and desethyl-atrazine (DEA) to the Louros River are mainly from tributaries and the agricultural area draining to the river estuary. The highest concentrations of these pesticides occured in May and June seasons, just after their application. The seasonal variation studies showed a continuous presence of triazines, alachlor and metolachlor, which were detected in the dissolved phase throughout the year at 0.02-0.27 μg/L, whereas the other pesticides exhibited a sporadic occurence related to agricultural and irrigation practices. Atrazine and its degradation product DEA are the most abundant herbicides discharged into Amvrakikos Gulf, followed by metolachlor, simazine and alachlor. Their annual mean flux was estimated as 122.7 g/day for atrazine, 127.5g/day for DEA, 49. 1 g/day for metolachlor, 43.9 g/day for simazine and 11.2 g/day for alachlor.