Structural features of humic acid of the coastal sediment in Ariake Sea tidelands: use of humic acid as an environmental indicator for river basins and coastal regions.

The structural features of humic acid (HA) at the sediment surface of the tideland at the Hayatsuegawa-river mouth at the Ariake Sea were investigated for the utilization of HA toward an environmental indicator of the features of the river basin and coastal region. 1H NMR analysis revealed a high-content hydrocarbon residue with a similar type of terrigenous HA. Direct and methylation-pyrolysis-GC analysis suggested the incorporation of long-chain carboxylate in HA in the tidelands.

Facile distinction of neutral and acidic tetraether lipids in archaea membrane by halogen atom adduct ions in electrospray ionization mass spectrometry.

Calditocaldarchaeol (neutral tetraether lipid) from Sulfolobus acidocaldarius (acidothermophilic archaea) and intact total lipid from the thermoacidophilic archaea Sulfolobus sp. was examined by electrospray ionization time-of-flight mass spectrometry in the negative-ion mode using high resolution. When the sample was injected as a solution in a 3:1 mixture of methanol (MeOH) and chloroform (CHCl(3)) using an infusion system, the total ether lipid afforded molecular-related ions as [M - H](-) for acidic polar lipids containing a phosphoric or sulfuric group, and as [M + Cl](-) ion for neutral glycolipids.