Sorption of dissolved organic matter by mineral soils of the Siberian forest tundra
Sorption of dissolved organic matter by mineral soils of the Siberian forest tundra
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DOI：
10.1111/j.1365-2486.2006.01203.x
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发表时间：
2006-10
影响因子：
11.6
通讯作者：
M. Kawahigashi;K. Kaiser;A. Rodionov;G. Guggenberger
中科院分区：
文献类型：
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作者：
M. Kawahigashi;K. Kaiser;A. Rodionov;G. Guggenberger
由于北极和亚北极表层水的净生产力较低，陆地排放的溶解有机物（DOM）对北极水生系统的碳和氮动态起着重要作用。吸附，通常控制DOM从土壤中的出口，可能会受到永久冻土制度。为了确认潜在的吸附控制释放的DOM在西伯利亚北方中部的永久冻土，我们研究了吸附DOM的矿物土壤的Gelisols和Inceptisols不同深度的活性层。与始成土的O层（686和706 mg C kg−1，45%和48% HoDOC）相比，冻成土O层中的水溶性有机质较少（338和407 mg C kg − 1），疏水部分（HoDOC）中的溶解有机碳（DOC）（63%和70%）更多。凝胶土A层和B层对DOC的吸附均较强，且对HoDOC的吸附较强.几乎所有的层位的始成土表现出较弱的吸附DOC比那些的Gelisol。的C层的Inceptisols，有一个弱的整体DOC吸附，吸附C的亲水部分（HiDOC）强于HoDOC。整体吸附性差以及HiDOC优先吸附的原因可能是C层的高pH值（pH>7.0）和氧化铁浓度较小。对于所有的土壤，HoDOC的吸附正相关的草酸和连二亚硫酸盐-柠檬酸可提取的铁。A层释放出大量DOC，HiDOC占46-80%。DOC释放量与土壤有机碳含量呈显著正相关（r=0.78，P<0.05）。从这些结果中，我们假设，大浓度的DOM包括大份额的HiDOC可以通过活性层薄（即在Gelisols）的矿质土壤，并进入流。具有深层活性层的土壤（即初始土），尽管其活性矿物含量较少，但由于DOM更频繁地渗入其厚的矿物层，因此可能释放很少的DOM。对始成土的研究结果与在低于65°50′的低纬度地区连接到叶尼塞的河流中观察到的连续或不连续永久冻土的情况一致。在北方流域，冻融土对DOM的吸附量较小，而DOM的浓度较大。然而，Gelisol优先保留HoDOC占主导地位的DOC朝北流。这种差异可以解释为额外的渗透水从有机层排放到溪流中，而不与矿物质土壤密切接触。
Because of low net production in arctic and subarctic surface water, dissolved organic matter (DOM) discharged from terrestrial settings plays an important role for carbon and nitrogen dynamics in arctic aquatic systems. Sorption, typically controlling the export of DOM from soil, may be influenced by the permafrost regime. To confirm the potential sorptive control on the release of DOM from permafrost soils in central northern Siberia, we examined the sorption of DOM by mineral soils of Gelisols and Inceptisols with varying depth of the active layer. Water‐soluble organic matter in the O horizons of the Gelisols was less (338 and 407 mg C kg−1) and comprised more dissolved organic carbon (DOC) in the hydrophobic fraction (HoDOC) (63% and 70%) than in the O horizons of the Inceptisols (686 and 706 mg C kg−1, 45% and 48% HoDOC). All A and B horizons from Gelisols sorbed DOC strongly, with a preference for HoDOC. Almost all horizons of the Inceptisols showed a weaker sorption of DOC than those of the Gelisols. The C horizons of the Inceptisols, having a weak overall DOC sorption, sorbed C in the hydrophilic fraction (HiDOC) stronger than HoDOC. The reason for the poor overall sorption and also the preferential sorption of HiDOC is likely the high pH (pH>7.0) of the C horizons and the smaller concentrations of iron oxides. For all soils, the sorption of HoDOC related positively to oxalate‐ and dithionite–citrate‐extractable iron. The A horizons released large amounts of DOC with 46–80% of HiDOC. The released DOC was significantly (r=0.78, P<0.05) correlated with the contents of soil organic carbon. From these results, we assume that large concentrations of DOM comprising large shares of HiDOC can pass mineral soils where the active layer is thin (i.e. in Gelisols), and enter streams. Soils with deep active layer (i.e. Inceptisols), may release little DOM because of more frequent infiltration of DOM into their thick mineral horizons despite their smaller contents of reactive, poorly crystalline minerals. The results obtained for the Inceptisols are in agreement with the situation observed for streams connecting to Yenisei at lower latitudes than 65°50′ with continuous to discontinuous permafrost. The smaller sorption of DOM by the Gelisols is in agreement with the larger DOM concentrations in more northern catchments. However, the Gelisols preferentially retained the HoDOC which dominates the DOC in streams towards north. This discrepancy can be explained by additional seepage water from the organic horizons that is discharged into streams without intensive contact with the mineral soil.