グルコースとアミノ酸の実験室と猪苗代湖堆積物中における消費に関する地球化学的反応速度論

Consumption rates of glucose, Ala (alanine) and Gly (glycine) in Maillard reaction were examined and compared with those in sediments. By means of monitoring the concentration change of glucose +Ala (or glucose + Gly) in aqueous solution, the reaction order of this condition was determined to be second-order. For the purpose of drawing Arrhenius plots, the measurements of change in the concentration of reactants were conducted at four different temperatures (65 , 80, 89 and 94℃) and the apparent activation energies and Arrhenius equations of glucose +Ala and glucose + Gly consumption were obtained. Influences on the reaction rates of these systems by CaC0_3 and mont (montmorillonite) were also examined under the same reaction conditions.
The apparent activation energy of glucose +Ala (E = 27.7 kcal/mol) was 8.3% lower than that of glucose + Gly (E = 30.2 kcal/mol) . This indicates that the reaction of glucose +Ala is more likely to occur at ordinary temperature in the surface sediments than that of glucose + Gly. The apparent activation energies in the presence of mont were 7.9-17.2% lower than those in the absence of mont, and the frequency factors were also lower in the presence of mont. It appears that mont apparently plays a role as a weak positive catalyser in this reaction. In order to compare the consumption rates in laboratory with those in sediments , the core sample (10- 50 cm) of sediment was collected in Lake Inawashiro, and the concentrations of glucose, Ala and Gly and TOC (Total Organic Carbon) were determined. Assuming possible reaction temperatures and time, the rate constants of decreasing glucose, Ala and Gly concentrations with increasing core depth were estimated to be 0.423, 5.20 and 1.20 (1 mol^<-1> yr.^<-1>), respectively. While, each rate constant in laboratory experiments calculated based on Arrhenius equation were 1.18X 10^<-2>, 1.18X 10^<-2> and 1.21 X l0^<-2> (1 mol^<-1> yr.^<-1>). Reaction rates in sediments were about l0^2 times as fast as those in laboratory experiments. This observation suggests that biodegradation rates of glucose, Ala and Gly by the activity of microorganisms in the surface sedimehts ( -50 cm) is about 10^2 times as fast as condensation rates of them.