Chronological sequence of humic acid Pg and its validity as environmental indicator

1)菌核颗粒的形态特征和化学成分，pg2)控制表层土壤中PG组分分布的因素3)古土壤和黄壤中腐植酸PG的年代序列4)各种腐殖酸PG在不同腐殖酸中的组成差异收集的菌核颗粒中的铝浓度是PG的来源，其发育受土壤中可交换性铝的数量的影响。此外，还阐明了表层土壤对PG的吸附强度受土壤中可交换性铝含量的调节。基于这些发现，我们认为土壤淋溶过程或凉湿条件下PG的形成是促进的。根据日本和德国埋藏腐殖层和黄土古土壤年代学序列的研究结果，PG残留在140~150ka的埋藏腐殖层中，并在50~60ka埋藏的Tephra和黄土古土壤中表现出较强的PG吸附强度。Pg的波动，称为Pg信号，与MIOS得到的过去温度的波动曲线有一定的对应关系。用高效液相色谱法对腐植酸PG的组成进行了研究，用高效液相色谱法将腐植酸绿色组分分离成10个组分。不同环境下形成的PG组分的鉴定可以在进一步的研究中讨论。

The following four subjects were promoted in this project to evaluate the validity of hurmic acid Pg as an environmental indicator.1) Morphological feature and chemical composition of sclerotia grains, the origin of Pg2) Factors regulating the distribution of Pg fraction in surface soils3) Chronological sequence of humic acid Pg in tephric and loessic paleosols4) Difference of the composition of humic acid Pg in various humic acidsAluminum concentration was significantly recognized in the collected sclerotia grains, which are the origin of Pg, and the its development revealed to be regulated by the amount of exchangeable aluminum in soils. Moreover, it was clarified that the strength of Pg absorption in surface soils was regulated by the amount of exchangeable aluminum in soils. Based on these findings, it is suggested that Pg formation is promoted under leaching process in soil, or under cool and wet condition. According to the results obtained by examining the chronological sequence of tephra and loess paleosol in Japan and Germany, Pg revealed to remain in the buried humic layers aged 140-150 ka and showed a strong Pg absorption strength in buried tephra and loess paleosols aged 50-60 ka. The fluctuation of Pg, named as Pg signal/had a tendency to correspond to the fluctuation curve of past temperature obtained by MIOS. The study on composition of humic acid Pg using HPLC performed to separate Pg (humic acid green fraction) into 10 fractions by HPLC. The identification of Pg fraction formed in different environment can be discussed in-further studies.