Beach macro-litter monitoring and floating microplastic in a coastal area of Indonesia.

Qualitative analysis of the structures of the polymers composing floating plastic debris was performed using attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), and the aging of the debris was assessed by measuring carbonyl group formation on the particle surfaces. Plastic material made up >75% of the 2313 items collected during a three-year survey. The size, shape and color of the microplastic were correlated with the polymer structure.

Photoreactivity of the fungicide chlorothalonil in aqueous medium.

The photoreactivity of chlorothalonil was studied by means of steady-state irradiation and laser-flash photolysis. Experiments were conducted in water containing acetonitrile as a co-solvent. This fungicide undergoes very slow phototransformation in the first stages of the reaction, but the consumption profile is auto-accelerated.

Fulvic acid-mediated phototransformation of mecoprop. A pH-dependent reaction.

Elliott soil fulvic acid sensitized the phototransformation of mecoprop in aqueous medium. The reaction was selective, leading to the main formation of 4-chloro-2-methylphenol in aerated and in deoxygenated neutral solution. In turn, 4-chloro-2-methylphenol underwent a fulvic acid-mediated phototransformation.

Inhibition of humic substances mediated photooxygenation of furfuryl alcohol by 2,4,6-trimethylphenol. Evidence for reactivity of the phenol with humic triplet excited states.

To probe the reactivity of 2,4,6-trimethylphenol with humic triplet excited states, we investigated its influence on the humic substances-mediated photooxygenation offurfuryl alcohol. Elliott soil humic and fulvic acids were employed for these experiments. When added in the concentration range of 10(-4) - 10(-3) M, 2,4,6-trimethylphenol inhibited furfuryl alcohol photooxygenation to an extent depending on its concentration.

Photolysis of fluometuron in the presence of natural water constituents.

Phototransformation of the herbicide fluometuron (1 microM) in natural sunlight was investigated in neutral Milli-Q water and in synthetic waters containing either fulvic acids, nitrate ions or both in order to mimic reactions taking place in aquatic environments. Fluometuron degradation followed a pseudo-first order kinetics. The reaction was faster in synthetic than in Milli-Q water.

Photochemical behaviour of phenylurea herbicides.

The photochemical behaviour of phenylurea herbicides in aqueous solution is highly dependent on the nature and position of substituents on the ring. Most of these herbicides are methylated on the urea moiety, the other substituents are usually halogens or methoxy groups. The main reaction involving the aromatic ring of unhalogenated phenylureas excited at wavelengths shorter than 300 nm is an intramolecular rearrangement, similar to photo-Fries rearrangement, whereas with halogenated derivatives, photohydrolysis is the main transformation pathway.