Academic literature on the topic 'Oxidizing capacity'

A wide range of trace gases, including dimethyl sulphide (DMS) and organohalogens, are formed in the surface oceans via biological and/or photochemical processes. Consequently, these gases become supersaturated in seawater relative to the overlying marine air, leading to a net flux to the atmosphere. Upon entering the atmosphere, they are subject to rapid oxidation or radical attack to produce highly reactive radical species which are involved in a number of important atmospheric and climatic processes. Organohalogens can affect the oxidizing capacity of the atmosphere by interacting with ozone, with implications for air quality, stratospheric ozone levels, and global radiative forcing. DMS and iodine-containing organohalogens (iodocarbons) can both contribute to direct and indirect impacts of aerosols on climate through the production of new particles and cloud condensation nuclei (CCN) in the clean marine atmosphere. Therefore, marine trace gases are considered a vital component of the earth’s climate system, and changes in the net production rate and subsequent sea-to-air flux could have an impact on globally important processes. In recent years, attention has turned to the impact that future ocean acidification may have on the production of such gases, with the greatest focus on DMS and organohalogens. In this chapter, the current state-of-the-art in this growing area of research is outlined. The oceans are a major source of sulphur (S), an element essential to all life, and marine emissions of the gas DMS (chemical formula (CH3)2S) represent a key pathway in the global biogeochemical sulphur cycle. The surface oceans are supersaturated with DMS relative to the atmosphere, resulting in a oneway flux from sea to air (Lovelock et al. 1972; Watson and Liss 1998). DMS is a breakdown product of the biogenically produced dimethyl sulphoniopropionate (DMSP): . . . (CH3)2S+CH2CH2COO- → (CH3)2S + CH2CHCOOH (acrylic acid) (11.1) . . . Single-celled marine phytoplankton are the chief producers of DMSP, and this reaction is catalysed intra- and extracellularly by the enzyme DMSP-lyase (Malin et al. 1992; Liss et al. 1997). The capacity of phytoplankton to produce DMSP varies between species, with prymnesiophytes considered to be the most prolific (Malin et al. 1992 ; Liss et al. 1997 ; Watson and Liss 1998).

In Japanese transuranic (TRU) waste disposal facilities, 129I is the most important key nuclide for the long-term safety assessment. Thus, the Kd values of I to natural minerals are important factor in the safety assessment. However, the degradation of cement materials in the repositories can produce high pH pore fluid which can affect the anion transport behavior. Therefore, it is necessary to understand the behavior of anions such as I− under the hyperalkaline conditions. The natural hyperalkaline spring water (pH>11) in the Oman ophiolite is known to be generated from the partly serp

Abstract The reduction of radioactive waste volume is an important issue for the management of the nuclear fuel cycle. The purpose of this study is to create a technique to drastically reduce low-level liquid waste generated by a spent fuel reprocessing plant employing PUREX technology. In the PUREX plant, NOx gas is used as an oxidizing reagent for adjustment of the Pu valence in the Pu purification stage. The spent NOx gas is recovered as nitric acid and a certain amount of recovered nitric acid becomes low-level waste (LLW). As NOx gas is produced by the chemical reaction of nitric acid and