连续提取对土壤腐殖质组分数量与特性的影响

Effect of Continuous NaOH/NaOH+Na_4P_2O_7 Extractions on the Content and Characteristic of Soil Humus Fractions

以暗棕壤为供试土壤,研究了NaOH和NaOH+Na4P2O7连续提取对土壤腐殖质组分数量和特性的影响。结果表明:用两种提取剂得到的土壤腐殖质组分总量相差不大,并且其中HA组分的数量均高于FA组分。随提取次数增加,胡敏酸(HA)、富里酸(FA)和胡敏素(HM)的绝对数量均下降,HA、FA的相对数量也下降,而HM的相对数量则增加。以NaOH为提取剂时,最后得到的腐殖质组分中FA的相对比例高于HA;而用NaOH+Na4P2O7为提取剂时,最后得到的腐殖质组分中HA的相对比例则高于FA。连续提取过程中,HA、FA的色调系数(Δlogk)和活化度(AD)通常呈增加趋势,而相对色度(RF)下降,说明后提取出的HA、FA的缩合度较低,脂族性较强。用RF来表征HA、FA特性变化更为合适。

The effects of continuous NaOH/NaOH ＋ Na4P2O7 extractions on the content and characteristic of soil humus fractions from dark - brown soil in Jilin Province, China were studied. The results showed that the whole organic carbon （OC） content of soil humus fractions extracted by using the above two extractants was not quite different, and OC content of HA fraction was higher than that of FA fraction. With the increasing of continuous extraction times, the absolute content of HA, FA and HM all decreased, the relative content of HA and FA also decreased, but the relative content of HM increased. A higher relative proportion of FA was obtained in the last extractable humus fractions when NaOH was used as extractant. During the course of continuous extraction, Alogk and activity degree of HA and FA generally showed an increasing tendency while RF decreased, indicating that the condensation degree of theirs declined while aliphaticity increased. RF is a more proper index for describing the characteristic change of HA and FA with extraction.