23:T46c,

The degradation of Carbaryl, a frequently used carbamate derivative pesticide, was carried out in batch reactors by photolytic ozonation. The influencing factors such as pH, pollutant concentration and ozone dosage were studied to optimize the reaction conditions. The maximum COD removal of 78.5% was achieved in three hours at alkaline pH 9. Increase in ozone dosage from 0.12 g/h to 0.48 g/h increased degradation rate. The apparent pseudo first order rate constant for photolytic ozonation and ozonation processes were found to be 0.0209 min $^{-1}$ and 0.0139 min $^{-1}$ respectively which indicated the presence of highly reactive hydroxyl radicals in photolytic ozonation. Complete mineralization needs longer ozonation time and only 48% TOC removal was achieved in three-hour duration. BOD5/COD ratio increased from 0.02 to 0.38 which facilitates coupling with secondary biological treatment.

24:T51e,

A major goal of NASA's Origins Program is to find habitable planets around other stars and determine which might harbor life. Determining whether or not an extrasolar planet harbors life requires an understanding of what spectral features (i.e., biosignatures) might result from life's presence. Consideration of potential biosignatures has tended to focus on spectral features of gases in Earth's modern atmosphere, particularly ozone, the photolytic product of biogenically produced molecular oxygen. But life existed on Earth for about 1½ billion years before the buildup of atmospheric oxygen. Inferred characteristics of Earth's earliest biosphere and studies of modern microbial ecosystems that share some of those characteristics suggest that organosulfur compounds, particularly methanethiol (CH₃SH, the sulfur analog of methanol), may have been biogenic products on early Earth. Similar production could take place on extrasolar Earth-like planets whose biota share functional chemical characteristics with Earth life. Since methanethiol and related organosulfur compounds (as well as carbon dioxide) absorb at wavelengths near or overlapping the 9.6-μm band of ozone, there is potential ambiguity in interpreting a feature around this wavelength in an extrasolar planet spectrum.

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Degradation of Carbaryl by Photolytic Ozonation

Biosignatures of Early Earths