Abstract

The mineralization of organic substances in soil solutions extracted from horizons of a podzolic soil using tension lysimeters was studied. The stability of dissolved organic matter (DOM) varies depending on the horizon. The maximum content of DOM resistant to biodegradation (mineralization degree <50%) was registered in upper organic horizons, and it decreases down the soil profile. The share of mineralized carbon is inversely proportional to the relative content of hydrophobic and phenolic fractions in the DOM. Organic matter extracted from horizon ELhi features the lowest share of mineralizable carbon (23%) amid the highest hydrophobic fraction content (44%). In the course of the oxidative transformation, the DOM aromaticity degree goes up: the extinction coefficient (SUVA280) increases by 2–12 times and the share of phenolic compounds by 2–10 times, while molecular mass decreases down to 5–5.5 kDa. These changes are manifested more intensely in solutions extracted from lower horizons. Therefore, the nondecomposable DOM residue consists of substances most resistant to decomposition.

中文翻译：

---

Podzolic土壤溶液中有机物矿化的模式

摘要

研究了用张力溶渗仪从梯形土壤层中提取的土壤溶液中有机物质的矿化作用。溶解有机物（DOM）的稳定性会随时间变化。在上部有机层中记录了最大的抗生物降解的DOM含量（矿化度<50％），并降低了土壤剖面。矿化碳的份额与DOM中疏水和酚类组分的相对含量成反比。从地平线ELhi提取的有机物的疏水性含量最高（44％），可矿化碳含量最低（23％）。在氧化转化过程中，DOM芳香度提高：消光系数（SUVA280）增加2至12倍，酚类化合物的份额增加2至10倍，而分子量下降至5至5.5 kDa。这些变化在从较低水平提取的解决方案中更加强烈地体现出来。因此，不可分解的DOM残基由最不易分解的物质组成。