Degradation of monuron in aqueous solution by ionizing radiation

In this study ionizing radiation induced degradation of monuron was investigated by γradiolysis. γ-radiolysis is one of the Advanced Oxidation processes (AOPs) which is very effective method for the degradation of organic water pollutants. The end-products and transient intermediates were studied in order to describe the degradation mechanism. The main reaction is OH● addition to the aromatic ring forming hydroxyl-cyclohexadienyl type radicals. In addition to this radical, aminyl and phenoxyl radicals have also some contribution to the degradation. Monuron as a halogenated compound is sensitive to the hydrated electron attack. Due to the oxidation, chemical oxygen demand and total organic carbon content decreases during irradiatin treatment. The efficiency of oxidation is high compared to other aromatics. Both, OH● and eaq take part in the dehalogenation reactions

Hydroxyl radical reaction with monuron

On the example of monuron, aromatic ring hydroxylation reactions were studied by Density Functional Theory calculations. In order to model the aqueous media the Solvation Model Density technique was used. Based on the relatively low activation energies of hydroxyl radical additions to ipso-, ortho- and meta-positions of the benzene ring (19-42 kJ mol−1 ) and also the Gibbs free energies ((-16)-(-41) kJ mol−1 ) of reactions, hydroxyl radical addition to any of these positions may take place. However, according to the calculations the ortho-addition is preferred in agreement with the experimental results. In these reactions hydroxycyclohexadienyl type radicals form. The first step in the mechanism of para-reaction is OH/Cl substitution without cyclohexadienyl type intermediate. The results of theoretical calculations here are also in agreement with the experimental results which show that the hydroxyl radical reaction with monuron in 40% results in Cl elimination

Recent developments in the data assimilation of AROME/HU numerical weather prediction model

A local three-dimensional variational data assimilation (DA) system was implemented operationally in AROME/HU (Application of Research to Operations at Mesoscale) non-hydrostatic mesoscale model at the Hungarian Meteorological Service (OMSZ) in 2013. In the first version, rapid update cycling (RUC) approach was employed with 3-hour frequency in local upper-air DA using conventional observations only. Optimal interpolation method was adopted for the surface data assimilation later in 2016. This paper describes the current developments showing the impact of more conventional and remote-sensing observations assimilated in this system, which reveals the benefit of additional local high-resolution observations. Furthermore, it is shown that an hourly assimilation-forecast cycle outperforms the 3-hourly updated system in our DA. Besides the upper-air assimilation developments, a simplified extended Kalman filter (SEKF) was also tested for surface data assimilation, showing promising performance on both the analyses and the forecasts of AROME/HU system