The molecular composition of dissolved organic matter in forest soils as a function of pH and temperature.
The molecular composition of dissolved organic matter in forest soils as a function of pH and temperature.
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DOI：
10.1371/journal.pone.0119188
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发表时间：
2015
期刊：
影响因子：
3.7
通讯作者：
Gleixner G
中科院分区：
文献类型：
--
作者：
Roth VN;Dittmar T;Gaupp R;Gleixner G
我们使用电喷雾电离傅里叶变换离子回旋共振质谱 (ESI-FT-ICR-MS) 检查了三个不同地点三个不同季节的森林土壤水的分子组成。我们检查了含氧土壤并检验了 pH 值和季节与溶解有机物 (DOM) 分子组成相关的假设。我们使用 ESI-FT-ICR-MS 的分子式及其相对强度进行统计分析。应用无约束和约束排序方法，我们观察到pH、溶解有机碳（DOC）浓度和季节是与DOM分子组成相关的主要因素。这一结果与之前的一项研究一致，其中 pH 值是叶尼塞河流域含氧河流和缺氧沼泽系统 DOM 之间分子差异的主要驱动因素。在较高的 pH 值下，分子式的不饱和度和氧化程度较低，分子尺寸较小，含氮化合物丰度较高。这些特征表明，较高丰度的单宁与较低的 pH 值有关，可能会抑制生物分解。较高 pH 值下较高的生物活性也可能与较高丰度的含氮化合物有关。比较季节，我们观察到从 3 月到 11 月，一年中不饱和度、分子多样性和含氮化合物的数量有所减少。冬季温度可能会抑制生物降解，这可能会导致更多样化的化合物谱的积累，直到温度再次升高。我们的研究结果表明，土壤孔隙水中 DOM 的分子组成是动态的，并且是生态系统活动、pH 和温度的函数。
We examined the molecular composition of forest soil water during three different seasons at three different sites, using electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FT-ICR-MS). We examined oxic soils and tested the hypothesis that pH and season correlate with the molecular composition of dissolved organic matter (DOM). We used molecular formulae and their relative intensity from ESI-FT-ICR-MS for statistical analysis. Applying unconstrained and constrained ordination methods, we observed that pH, dissolved organic carbon (DOC) concentration and season were the main factors correlating with DOM molecular composition. This result is consistent with a previous study where pH was a main driver of the molecular differences between DOM from oxic rivers and anoxic bog systems in the Yenisei River catchment. At a higher pH, the molecular formulae had a lower degree of unsaturation and oxygenation, lower molecular size and a higher abundance of nitrogen-containing compounds. These characteristics suggest a higher abundance of tannin connected to lower pH that possibly inhibited biological decomposition. Higher biological activity at a higher pH might also be related to the higher abundance of nitrogen-containing compounds. Comparing the seasons, we observed a decrease in unsaturation, molecular diversity and the number of nitrogen-containing compounds in the course of the year from March to November. Temperature possibly inhibited biological degradation during winter, which could cause the accumulation of a more diverse compound spectrum until the temperature increased again. Our findings suggest that the molecular composition of DOM in soil pore waters is dynamic and a function of ecosystem activity, pH and temperature.
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