Correlation between derivatographic and chemiluminescence analysis data in relation to elemental composition of humic acids

Humic acids from mineral soils (podsol, black-earth, rusty soil) and organic peat-muck, soil were examined. Two processes of oxidation of the humic acids were compared. The oxidation with air was examined through the derivatographic analysis. Differential curve of the change of temperature (DTA) and differential curve of mass sample changing (DTG) were recorded and two different exothermic effects of thermal decomposition were observed, One of them in the low temperature region (229-321 degrees C) is characterized by the ratio of areas under low (L) temperature peaks on DTA and DTG curves (DTA(L)/DTG(L)). The second one in the high temperature region (395-459 degrees C) is characterized by the ratio of areas under high (H) temperature peaks (DTA(H)/DTG(H)), The second process of oxidation with H2O2 in the water solution was investigated through chemiluminescence measurements. The chemiluminescence appearing together with the oxidation process of humic acids was characterized by initial J(0) and integral Sigma J intensity of chemiluminescence. Results obtained can be summarized as follows: 1) there is a significant negative correlation between DTA(L)/DTG(L) and J(0); 2) there is a significant positive correlation between N/C and Sigma J; and, 3) there is a probable negative correlation between DTA(L)/DTG(H) and J(0), and a probable positive correlation between H/C and DTA(L)/DTG(L).