[1] Isotopic studies indicate that natural perchlorate is produced on Earth in arid environments by the oxidation of chlorine species through pathways involving ozone or its photochemical products. With this analogy, we propose that the arid environment on Mars may have given rise to perchlorate through the action of atmospheric oxidants. A variety of hypothetical pathways can be proposed inclu...

In this study, we evaluated the effectiveness of photochemical reflectance index (PRI) and non-photochemical quenching (NPQ) for assessing water stress in maize for the purpose of developing remote sensing techniques for monitoring water deficits in crops. Leaf-level chlorophyll fluorescence and canopy-level PRI were measured concurrently over a maize field with five different irrigation treatm...

We show that the main photochemical processes involved in the phototransformation of anionic ibuprofen (IBP) in surface waters are the reaction with (•)OH, the direct photolysis and possibly the reaction with the triplet states of chromophoric dissolved organic matter ((3)CDOM). These conclusions were derived by use of a model of surface water photochemistry, which adopted measured parameters o...

Sonolysis and photochemical degradation of different compounds such as chlorinated aliphatic hydrocarbons are among the recent advanced oxidation processes. Perchloroethylene is one of these compounds that has been mainly used as a solvent and degreaser. In this work, elimination of perchloroethylene in aqueous solution by ultrasonic irradiation, andphotochemical oxidation by ultra violet ray a...

The principal long-term objective of this work is to determine what factors control the distribution and dynamics of the chromophore-containing constituents of dissolved organic matter (CDOM) in marine and estuarine waters. Two important secondary objectives are 1) to elucidate the photochemical properties of the CDOM and how photochemical reactions affect the optical properties and secondary r...

The photochemistry of the ClO dimer (ClOOCl) plays a central role in the catalytic destruction of polar stratospheric ozone. In spite of decades of intense investigations, some of its laboratory photochemical data had not reached the desired accuracy to allow a reliable simulation of the stratospheric ozone loss until recently. Inevitable impurities in ClOOCl samples have obstructed conventiona...

Exposure of plants to irradiances far above the light saturation point of photosynthesis, known as highlight stress, induces various responses including light adaptation of the photosynthetic apparatus and chloroplast ultrastructure by formation of sun-type chloroplasts. The latter possess a lower cross section for light absorption (less light-harvesting chlorophyll proteins) and higher rates o...

the photocatalytic process using semiconductors with a nanostructure is one of the technologies usedfor the destructive oxidation of organic compounds such as surfactants. in this paper, thephotocatalytic degradation of cetyl pyridinium chloride (cpc), was investigated in aqueous phaseusing various semiconductors such as titanium dioxide (ti02), zinc oxide (zno), stannic oxide(sn02). the degrad...

air pollution is one of the most important problems in urban areas that always threaten citizen's health. photochemical smog is one of the main factors of air pollution in large cities like tehran. usually smog is not only a part of nature, but is being analyzed as an independent matter, which highly affects on the nature. it has been used as relationship between atmospheric elements such as te...