Novel imazethapyr detoxification applying advanced oxidation processes.

Different degradation methods have been applied to assess the suitability of advanced oxidation process (AOPs) to promote mineralization of imazethapyr [(RS)-5-ethyl-2-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl)nicotinic acid], a widely used imidazolinone class herbicide, the persistence of which has been demonstrated in surface and ground waters destined to human uses. Independent of the oxidation process assessed, the decomposition of imazethapyr always followed a pseudo-first order kinetic. The direct UV-irradiation (UV) of the herbicide as well as its oxidation with ozone (O₃), and hydrogen peroxide tied to UV-irradiation (H₂O₂/UV) were sufficiently slow to permit the identification of intermediate products, the formation pathway of which has been proposed.

2-Hydroxypyridine photolytic degradation by 254 nm UV irradiation at different conditions.

The degradation and mineralisation of (400 mL, 3.15 mM) aqueous solutions of 2-hydroxypyridine (2-HPY), a primary intermediate formed during the photolytic degradation of 2-chloropyridine (2-CPY), 2-bromopyridine (2-BPY) and 2-iodopyridine (2-IPY), was studied at 50 degrees C, under 254 nm UV irradiation in a range of conditions. The rate of 2-HPY disappearance was found to heavily depend on agitation, dissolved oxygen, pH and hydroxyl radical scavenger presence.

Photolytic removal and mineralisation of 2-halogenated pyridines.

The photolytic destruction and mineralisation of 2-halogenated pyridines (2-HalPYs) was studied in a range of conditions by means of ultraviolet irradiation at 254 nm. In all cases pseudo-first order kinetics satisfactorily describe the degradation process. Key decomposition products were identified and primary reaction pathways are proposed.

Effects of dissolved carboxylates and carbonates on the adsorption properties of thiuram disulfate pesticides.

The adsorption of thiram and disulfiram onto alpha-Al2O3 and montmorillonite clay has been studied in the presence of small carboxylate anions, bicarbonate, formate, and oxalate. At natural concentrations, HCO3- enhances dramatically the adsorption of both pesticides on alpha-Al2O3 and clay. An analogous significant enhancement of pesticide adsorption is also observed in the presence of formate and oxalate.

The status of pesticide pollution in surface waters (rivers and lakes) of Greece. Part I. Review on occurrence and levels.

This review evaluates and summarizes the results of long-term research projects, monitoring programs and published papers concerning the pollution of surface waters (rivers and lakes) of Greece by pesticides. Pesticide classes mostly detected involve herbicides used extensively in corn, cotton and rice production, organophosphorus insecticides as well as the banned organochlorines insecticides due to their persistence in the aquatic environment. The compounds most frequently detected were atrazine, simazine, alachlor, metolachlor and trifluralin of the herbicides, diazinon, parathion methyl of the insecticides and lindane, endosulfan and aldrin of the organochlorine pesticides.

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.

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.