The role of hydrogen peroxide in natural aquatic media

Abstract

PACS. 75.10.Jm -Quantized spin models. PACS. 75.40.Cx -Static properties (order parameter, static susceptibility, heat capacities, critical exponents, etc.). PACS. 75.45.+j -Macroscopic quantum phenomena in magnetic systems.Abstract. -We study a system with spin-Peierls dimerization in next-nearest-neighbor (NNN) interaction and also the presence of nearest-neighbor (NN) interaction under a magnetic field. We predict the existence of different fractionally quantized magnetization plateaus with many interesting physical properties. The effect of the frustrating NNN interaction and the role of quantum fluctuations are also explored for different magnetization plateaus. We explain more physically the gapless state of spin spectrum for small values of the frustrating NNN interaction. The transition from commensurate gapped phase to incommensurate Luttinger liquid phase is of Mott-δ type.c EDP Sciences Article published by EDP Sciences and available at http://www.edpsciences.org/epl or http://dx.doi.org/10.1209/epl/i2005-10183-2 c with ∆. B) We present the curves for different magnetization plateaus. m = 1/2 is independent of ∆ and J 2 J 1 in contrast with m = 1/4, 0. The curves for m = 1/4, 0 plateaus are for ∆ = 0.5, 0.4, 0.3, respectively, from top to bottom.

The Impact of Human Activities on Freshwater Aquatic Systems

“…A similar range of variation has been observed in natural waters [6,11,16]. An increase in the hydrogen peroxide concentration in the environment (intracellular as well as interreservoir) will eventually cause an increase in the initiation rate of active intermediates destroying biologically significant molecules.…”

“…The hydrogen peroxide concentration in cells of mammals and microalgae varies mainly within the range 10 -7 ... 10 -6 M; however, it may also reach 10 -5 M under certain circumstances [6,13,20]. A similar range of variation has been observed in natural waters [6,11,16].…”

“…In the presence of ferric and manganese hydroxides as catalysts, SO 2 interacts with H 2 O 2 in the atmospheric moisture, forming sulfuric acid (H 2 SO 4 ) [6]. In this case, HSO 3 -ions which effectively interact with H 2 O 2 appear in the precipitation instead of hydrogen peroxide.…”

“…UV-irradiation of waste (and natural) water gives rise to a large variety of photochemical processes [6,16,33,34]. The use of different types of low-pressure lamps (λ = 254 nm) as UV-irradiation sources, results in effective disinfection of the water.…”

“…The principal ways are: disproportionation of superoxide radicals [9], two-electron reduction of singlet oxygen [10] and release by microalgae, either as a secondary product of photosynthesis [11,12] or as a result of other photochemical transformations in algal cells [11,13,14]. In contrast to dissolved oxygen, the concentration of hydrogen peroxide in natural water varies within a wide range [6,15,16] being subject to diurnal and seasonal variations [11].…”