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选择亚热带地区3种典型稻田和旱地土壤,应用碳同位素14C-CO2标记示踪技术结合室内模拟培养试验,研究自养微生物同化碳(“新碳”)在土壤碳库中的矿化和转化特征.结果表明:在100 d的培养期内,“新碳”的矿化经历了先上升、10 d后缓慢下降、最后渐趋稳定的3个阶段.“新碳”的矿化比例为8.0%~26.9%,矿化速率为0.01~0.22μg14C·g-1·d-1,其中,稻田土壤为0.01~0.22μg14C·g-1·d-1,旱地土壤为0.01~0.08μg14C·g-1·d-1,而原有有机碳的矿化比例为1.6%~5.7%,矿化速率为1.3~25.66μg C·g-1·d-1.土壤活性碳库[可溶性有机碳(DOC)、微生物生物量碳(MBC)]中,14C-DOC在培养初期(0~10 d)先上升,升高幅度达0.3 mg·kg-1,10~30 d又迅速下降,下降幅度达0.42 mg·kg-1,至30 d后缓慢下降.14C-MBC的波动与14C-DOC不同,在培养初期(0~10 d)先迅速下降,10~30 d又迅速上升,至40 d后缓慢下降并趋于稳定.水稻土14C-DOC/DOC的转化更新速率明显大于旱地,而旱地14C-MBC/MBC的转化更新速率大于水稻土.
Three typical paddy fields and dryland soil in the subtropical area were selected to study the mineralization of autotrophic microbial assimilation carbon (“XinCu”) in the soil carbon pool by using 14C-CO2 labeled tracer of carbon isotope and indoor simulated cultivation experiment The results showed that during the incubation period of 100 d, the mineralization of “new carbon ” experienced three stages of first rising, then gradually decreasing after 10 days and finally becoming stable. Mineralization rate was 8.0% ~ 26.9%, mineralization rate was 0.01 ~ 0.22μg14C · g-1 · d-1, of which paddy soil was 0.01 ~ 0.22μg14C · g-1 · d-1, 0.08μg14C · g-1 · d-1, while the original organic carbon mineralization rate was 1.6% ~ 5.7% and the mineralization rate was 1.3 ~ 25.66μg C · g-1 · d-1. (DOC) and microbial biomass carbon (MBC)], 14C-DOC firstly increased at the early stage of culture (0-10 d) with an increase of 0.3 mg · kg-1 and rapidly decreased after 10-30 d , Which decreased slowly by 0.42 mg · kg-1 and decreased slowly after 30 days.The fluctuation of 14C-MBC was different from that of 14C-DOC in the early stage of culture (0 ~ 10 days), and then rapidly increased from 10 to 30 days It declined slowly and stabilized after 40 days.The conversion rate of 14C-DOC / DOC in paddy soil was significantly higher In dryland, the conversion rate of 14C-MBC / MBC in dry land was higher than that of paddy soil.