Effect of Black Carbon Addition on Soil Organic Carbon Decomposition
|School||Fujian Normal University|
|Keywords||Black carbon (BC) Pyrolysis temperatures Soil organic carbon decomposition Black carbon decomposition Isotopic labeling|
Black carbon (BC) is an important component in the global soil carbon pool. Its role however is less known yet played in soil organic carbon mineralization. Firstly in this thesis two kinds of material,13C-labbeled (L) and unlabeled rice straw (R), were pyrolysed at different temperature ranged from 250℃to 750℃at 100℃interval for producing black carbon material and the characteristics of produced black carbon such as carbon contents,813C, structural properties as well as producing efficiency related to pyrolysing temperature were researched, and secondly, two kinds of black carbon material produced above at 250℃and 350℃were chosen to conduct addition/incubation experiments with soils once long grown sugarcane for 112 days at 25℃to investage the effect of black carbon on soil organic carbon mineralization and the stability of its own in the soil. The major results are summarized as follows.The remnant amounts after pyrolysing of rice straw as wel as their organic carbon contents were decreased as the burning temperature rises and shown a significant negative correlation to the pyrolysis temperature, which demonstrated the formation of black carbon was importantly affected by the pyrolysis temperature. Black carbon functional groups mainly includes aromatic carbon, alkyl carbon, oxyalkyl carbon, carboxyl silane carbon, carbonyl carbon etc. and the aromatic degree was intensified with pyrolysis temperature rise.The soil CO2 releasing rates from black carbon treated soils presented a general trend of early quick and then slow in the incubation periods. The added black carbon promoted the native soil carbon decomposition in the first three incubation days and inhibited the process from the 7th to the 112th days; then after 112 days, the adding of black carbon showed negative priming effects on the decomposition of soil organic carbon and meanwhile the content of soil microbial biomass carbon decreases.The decomposition rates of black carbon added in the soil decreases in the cultivation process and averaged 2.3% and 2.0% for L250 and L350, respectively, indicating that the decomposition of black carbon is a very slow process.