Two-dimensional distribution of soil organic carbon at intact macropore surfaces in BT-horizons
Two-dimensional distribution of soil organic carbon at intact macropore surfaces in BT-horizons
复制标题
BT层完整大孔表面土壤有机碳的二维分布
DOI：
10.1016/j.still.2017.10.002
复制
发表时间：
2018
影响因子：
6.5
通讯作者：
中科院分区：
文献类型：
--
作者：
在结构性土壤中，与基质相比，生物孔、收缩裂缝和团聚体间隙的表面通常富含有机质(OM)。有机质在大孔表面的小尺度分布影响着大孔中的优先流动、传质和有机质周转。虽然可以观察到有机质成分在完整表面的毫米尺度空间分布，但由于采用了合适的方法，有机碳(OC)含量的分布到目前为止仍然有限。其目的是开发和测试一种在毫米到厘米尺度上量化完整大孔表面上的二维(2D)OC分布的方法。我们结合了漫反射红外傅里叶变换(漂移)光谱和OC分析，从大孔表面手工分离出几毫克的参考样品。用作图的方法测量了蚯蚓洞穴的完整表面、有无粘土有机涂层的裂缝以及黄土和冰川上发育的Luvisol的BT层的单孔填充物(针孔)的漂移光谱。用元素同位素比值质谱仪(EA-IRMS)测定了样品中有机碳的含量，并用偏最小二乘回归(PLSR)对其漂移光谱进行了关联。通过PLSR模型，利用漂移映射光谱预测了完整大孔表面有机碳含量的二维空间分布。这些图谱显示了大孔有机碳含量在毫米尺度上的差异，这往往与大孔类型表面的二维分布有关。PLSR的验证表明，土壤有机碳含量的实测值与预测值的R2分别为0.77(黄土)和0.83(耕地)。完整表面的微地形和粘土-有机表面层厚度的变化降低了OC值的预测精度。完整土壤大孔隙表面的漂移作图光谱适合于定量最外表层的2D有机碳分布。大孔表面有机碳含量的非均匀小尺度空间分布意味着，在研究结构性土壤中的域间传质和有机质周转时，需要更具体地考虑这些大孔壁。
In structured soils, the surfaces of biopores, shrinkage cracks, and inter-aggregate spaces are often enriched in organic matter (OM) as compared to the matrix. The small-scale distribution of OM at macropore surfaces is affecting preferential flow, mass transfer, and OM turnover in macropores. While the mm-scale spatial distribution of the OM composition at intact surfaces could be observed, the distribution of the organic carbon (OC) content remained limited to date due to a suitable approach. The objective was to develop and test a method for quantifying the two-dimensional (2D) OC distribution at intact macropore surfaces at the mm-to-cm scale. We combined diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy and OC analyses of reference samples of few milligrams manually separated from macropore surfaces. DRIFT spectra were measured in a mapping approach at intact surfaces from earthworm burrows, cracks with and without clay-organic coatings, and single pore fillings (‘pinholes’) from Bt-horizons of Luvisols developed on loess and glacial till. The sample’s OC contents were determined with elemental isotope ratio mass spectrometry (EA-IRMS) and related to the DRIFT spectra by partial least squares regression (PLSR). The DRIFT mapping spectra were used to predict the 2D spatial distribution of the OC content at intact macropore surfaces via the PLSR models. The maps revealed mm-scale differences in the OC contents of the macropores which were often related to the 2D distribution of the macropore type surfaces. The validation of the PLSR showed R2values of 0.77 (loess) and 0.83 (till) between measured and predicted OC contents. The prediction accuracy of the OC values was reduced by the micro-topography of the intact surfaces and by a variable thickness of the clay-organic surface layer. DRIFT mapping spectra from intact soil macropore surfaces were suitable to quantify the 2D OC distribution of the outermost surface layer. The heterogeneous small-scale spatial distribution of the OC contents at macropore surfaces implies a more specific consideration of these macropore walls when studying inter-domain mass transfer and OM turnover in structured soils.
登录
查看更多内容
通过共焦激光扫描显微镜评估 Bt 层中生物孔和裂缝的粗糙度
影响因子：
2.5
作者：
通讯作者：
--
完整生物孔和裂缝表面有机质成分的毫米级分布
影响因子：
4.2
作者：
Ellerbrock
通讯作者：
Ellerbrock
影响因子：
2.5
作者：
Leue, Martin;Eckhardt, Kai-Uwe;Leinweber, Peter
通讯作者：
Leinweber, Peter
修正微地形对完整土壤骨料表面有机质 DRIFT 绘图信号的影响
影响因子：
2.9
作者：
M. Leue;H. Gerke;R. Ellerbrock
通讯作者：
R. Ellerbrock
影响因子：
3.5
作者：
GRAF, RT;KOENIG, JL;ISHIDA, H
通讯作者：
ISHIDA, H