Antecedent soil moisture prior to freezing can affect quantity, composition and stability of soil dissolved organic matter during thaw.
Antecedent soil moisture prior to freezing can affect quantity, composition and stability of soil dissolved organic matter during thaw.
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冻结前的土壤湿度会影响解冻期间土壤溶解有机物的数量、组成和稳定性
DOI：
10.1038/s41598-017-06563-8
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发表时间：
2017-07-25
影响因子：
4.6
通讯作者：
Li F
中科院分区：
文献类型：
--
作者：
Wu H;Xu X;Cheng W;Fu P;Li F
春季土壤解冻过程中会释放出大量的溶解性有机质（DOM），但其生物有效性及其组成尚不清楚。在10%~ 90%含水率的9种土壤含水量条件下，通过测定土壤CO2通量、可生物降解溶解有机碳（BDOC）和氮（BDON），紫外吸光度和荧光激发-发射矩阵的平行因子分析。土壤中BDOC、BDON、DOC和DON浓度在30%左右最低，较高和较低的土壤含水量均使土壤中DOM和BDOM浓度增加。随着WFPS的增加，土壤DOM的主要成分由类胡敏酸类物质向类富里酸类物质转化，DOM的生物来源逐渐增加。类蛋白质组分占土壤DOM的8-20%，受植被类型和木质部植物群落的单独和交互作用影响。结果表明，冬季冻融前WFPS> 50%的森林土壤可释放出大量富里酸类DOM，这些DOM在春季雪融过程中易被生物降解并以CO2形式释放或随地下水流失。
There are large amounts of dissolved organic matter (DOM) released into the soil during spring thaw, but its bioavailability and components are still unknown. The quantity, composition and stability of DOM in water extracts of forest soils during thaw were studied after two-month freezing with 9 levels of soil moisture ranging from 10% to 90% water-filled pore space (WFPS), by measuring soil carbon dioxide (CO2) flux, biodegradable dissolved organic carbon (BDOC) and nitrogen (BDON), ultraviolet absorbance and parallel factor analysis of fluorescence excitation-emission matrices. Concentrations of BDOC, BDON, DOC and DON were lowest around 30% WFPS and relatively higher and lower soil moisture both increased DOM and BDOM concentrations in thawing soil. With increasing WFPS, the dominant component of soil DOM changed from humic acid-like substances to fulvic acid-like substances and the biological origin of DOM increased gradually. The protein-like component accounted for 8–20% of soil DOM and was affected by vegetation type and WFPS singly and interactively. The results implied that forest soils with more than 50% WFPS before winter freezing could release large amounts of fulvic acid-like DOM, which would be easily biodegraded and emitted as CO2or run off with ground water during spring snow thaw.
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