Youki Ose

Aldehydes as mutagens formed by ozonation of humic substances

Humic substances and p-hydroxybenzaldehyde, one of their components, were ozonated and quantitative analysis of the mutagenic aldehydes (formaldehyde, acetaldehyde, glyoxal, glyoxylic acid and methylglyoxal) was performed. Glyoxal and glyoxylic acid were the main mutagenic compounds. The ozone-treated solutions were flowed through a granular activated carbon (GAC) column and the KMnO4 consumed of the effluent decreased to about 40-50%. Most of the aldehydes formed by ozonation reduced, but glyoxal increased.

Mutagenicity of the components of ozonated humic substance

Eight components of humic substances were ozonated. Mutagenic activity was found with TA100 with and without S9 mix for all ozonated components. Ozonated products of p-hydroxybenzaldehyde were separated into five fractions by silica gel chromatography and each fraction subjected to mutagenicity assay. Mutagenic activity was found in the chloroform and chloroform-acetone (1:1) fractions. The compounds in these fractions were identified, and aldehydes such as formaldehyde, acetaldehyde, glyoxal, glyoxylic acid and methyl glyoxal were found to be mutagenic. Mutagenic compounds are present in the polar fraction.

Mutagenicity of ozonation and chlorination products from p-hydroxybenzaldehyde

p-Hydroxybenzaldehyde, a component of soil humic substances, was ozonated and chlorinated. The ether extract and the residue were subjected to the Ames assay; mutagenic activities were identified. The non-ionic resin CSP800 and the anion exchange resin CHPA25 were used for separation of mutagenic compounds. The compounds in the water layer were not adsorbed on CSP800 or CHPA25 and exhibited strong mutagenic activity. Mutagenic activity was reduced as the added chlorine was increased. Ether extracts were analyzed by gas chromatography-mass spectrometry (GC-MS) and chloral, 1,3-dichloro-2-propanone, 1,2,3-trichloro-1-propene, tetrachloroethylene and 1,1,1,3,3-pentachloro-2-propanone were identified as mutagenic compounds.

Generation of mutagenicity by ozonation of humic substances' components

Components of humic substances, such as vanillin, syringaldehyde, vanillic acid and di-n-butylphtalate, were ozonated and subjected to the mutagenicity assay using Salmonella typhimurium TA 98 and 100 with and without S9 mix. The strong mutagenic activity was found on all components except di-n-butylphtalate by strain TA 100 with and without S9 mix. Substances with strong mutagenic activity in ozonated vanillin were water-soluble and were slightly extracted with benzene, dichloromethane and ethyl acetate. Following gel chromatography on Sephadex G-10, the strong mutagens generated by ozonation were found with molecular weights greater than 300.

Behavior Of Glyoxal During Granular Activated Carbon Treatment

Glyoxal, which was the strong mutagen formed by ozonation of humic substances, was treated with granular activated carbon (GAC) and the behavior of glyoxal was investigated. Glyoxal itself was adsorbed well on GAC at pH 5–7. But, glyoxal increased by GAC treatment of ozonated humic substances when the ozone dose was insufficient to decolorize the humic substances. The precursors of glyoxal may be among other ozonated products which may be changed to glyoxal on GAC.

Mutagenicity of ozonated and chlorinated humic substances

Abstract Humic substances were ozonated and subjected to the mutagenicity assay with Salmonella typhimurium TA 98 and 100. Both of ozonated humic substances and their dichloromethane extracts were not mutagenic. Then, ozonated humic substances were chlorinated, extracted with ether at pH 7 and 1.5, and subjected to the mutagenicity assay. Both of the ether extracts found to be mutagenic on TA 100. The ozonation and ozonation‐chlorination products of humic substances were determined by gas chromatography‐mass spectrometry (GC‐MS) and mutagenic aldehydes were identified.

Evaluation of mutagenic activity of ozonated and ozonated‐chlorinated humic substances by sos chromotest

Abstract SOS chromotest was used to determine the mutagenic activity by ozonation and ozonation‐chlorination of humic substances. By ozonation only, mutagenic activity decreased gradually with the progress of ozonation. Also, by ozonation‐chlorination, mutagenic activity decreased compared with chlorination only. But, the mutagenic activity could not be eliminate completely by combination of preozonation and chlorination. We tried to eliminate this mutagenic activity by granular activated carbon (GAC) treatment, but it was not effective.

Suppression of sediment oxygen demand with lime-based treatments

Abstract Sediment oxygen consumption was measured using a continuous flow-through system before and after the application of lime-based material onto the surfacial sediment. Lime-based amendments including quick-lime, calcium hydrate, a mixture of calcium hydrate and magnesium hydrate and dolomitic lime were effective in suppressing sediment oxygen consumption, while precipitated calcium carbonate had little effect. The doses of quick-lime required to suppress the biological respiration is estimated to be > 50 g/m 2 for river sediments and >25 g/m 2 for sludge, respectively.