No abstract

A b s t r a c t :The decomposition characteristics of particulate organic matter (POM) sampled with plankton nets in Hiroshima Bay were investigated under aerobic conditions in a laboratory experiment.The POM derived from plankton consisted of both a labile fraction (70-80 % of the whole) and a refractory fraction (20-30°,%). The labile fraction was completely decomposed within 40 days at 20°C. Although the concentrations of particulate organic carbon(POC) decreased gradually with time, an apparent lag phase was recognized in the decomposition of particulate phosphorus(PP) at an early stage, which might result from a specific uptake of dissolved inorganic phosphorus(DIP) by bacteria. A comparison of the metabolic activity between dissolved organic matter(DOM) and POM by measuring ATP contents showed that the former was one order of magnitude larger than the latter.On the other hand, there was no significant difference among the decomposition rates of POM collected at various depths. The change of the first-order rate constant(k) for the POM decomposition by temperature was expressed as k = 0.0329 exp(0.0644T), and the Q10 value was 1.94. There were fairly large variances in k values obtained from the various plankton species. The k values averaged 0.144 d a y -l a n d ranged from 0.078 to 0.20 day I at 20°C.

No abstract

The reducing elution of chromium(VI) by anion exchange using sodium sulfite has been investigated. Chromium(VI) is reduced to chromium(III), which is eluted quickly and easily separated from interfering substances by colorimetry using diphenylcarbazide.