Overcoming carbonate interference on labile soil organic matter peaks for midDRIFTS analysis
Overcoming carbonate interference on labile soil organic matter peaks for midDRIFTS analysis
复制标题
DOI：
10.1016/j.soilbio.2016.05.010
复制
发表时间：
2016-08
影响因子：
9.7
通讯作者：
Reza Mirzaeitalarposhti;M. S. Demyan;F. Rasche;G. Cadisch;T. Müller
中科院分区：
文献类型：
--
作者：
Reza Mirzaeitalarposhti;M. S. Demyan;F. Rasche;G. Cadisch;T. Müller
中红外光谱分析在土壤有机质(SOM)的定性和定量分析中取得了不同程度的成功。本研究评价了土壤碳酸盐对土壤有机质质量和组成的影响，探讨了利用中波段漫反射红外傅里叶变换光谱(MidDRIFTS)获得的比峰面积法作为土壤有机质质量和组成指标的可行性。在两个不同的农业生态区(Kraichgau(K)和Swabian Alb(SA)，德国)，土壤中碳酸盐含量高达41 g/kg−1土壤的DRIFTS中峰面积(2930 cm−1)与微生物生物量碳和氮(CMIC，NMIC)和热水可提取碳和氮(CHWE，NHWE)有关。尽管2930 cm−1峰显示了其作为土壤活性碳指标的潜在用途，但2930 cm−1的相对峰面积(rPAnt2910 cm−1)与不稳定的SOM组分(R2=0.31-0.45)之间的回归性能较差，这是由于无机碳(IC)潜在地干扰了这一特定的峰。为了避免碳酸盐干扰，利用总有机碳和总有机碳组成的多元线性回归模型，建立了一个基于光谱的系数，用来预测非酸和酸处理土壤光谱(ΔPA 2930 cm−1)在2930cmPf1处的峰面积之差。未处理光谱(PAnt2930 cm−1)的峰面积(PAnt2930 cm−1)用碳酸盐(PAcorr2930 cm−1)的系数0.21进行了校正，这极大地改善了与CMIC、NMIC、CHWE和NHWE的关系(R2=0.68-0.75；P<；=0.0001)。我们进一步利用PAnt713 Cm−1(分配给碳酸盐(主要是方解石))与PAnt2930 Cm−1(PAnt2930 Cm−1)(ΔPATIC2930 Cm−1)之间的关系，进一步建立了PAnt2930 cm PAT1的回归方程，以供将来应用。我们的结论是，在碳酸盐化土壤中，一旦碳酸盐干扰被校正，PA 2930 cm−1有很高的潜力作为土壤有机质组成的指示剂。提出的方法不需要进行多变量校正，所开发的光谱指数(PAcorr2930 cm−1)适合于准确预测不稳定的土壤有机质，而不需要额外的实验室测量。对于该方法的普遍适用性，应在不同TOC和TIC含量的其他土壤类型上进行测试。
Mid-infrared spectroscopy has been used with various degrees of success in quantitative and qualitative analysis of soil organic matter (SOM). This study evaluated the spectral interference caused by soil carbonates on the feasibility of using the specific peak area approach obtained by diffuse reflectance infrared Fourier transform spectroscopy in mid-range (midDRIFTS) as an indicator of SOM quality and composition. A midDRIFTS peak area corresponding to more labile SOM compounds (2930 cm−1) was related to microbial biomass carbon and nitrogen (Cmic, Nmic) and hot water extractable carbon and nitrogen (CHWE, NHWE) across two contrasting agroecological regions (Kraichgau (K) and Swabian Alb (SA), Germany) with soils containing carbonates up to 41 g kg−1soil. Although, the 2930 cm−1peak showed its potential use as an index for representing labile soil carbon, a poor regression performance between the relative peak area at 2930 cm−1(rPAnt2910 cm−1) and labile SOM fractions (R2= 0.31–0.45) was attributed to inorganic carbon (IC) potentially interfering with this particular peak. To avoid carbonate interference, a spectral-based coefficient was developed using a multiple linear regression model consisting of TOC and TIC as predictors of the difference between peak areas at 2930 cm−1of non-acid and acid treated spectra (ΔPA 2930 cm−1) of bulk soils. Peak areas at 2930 cm−1of non treated spectra (PAnt2930 cm−1) were corrected using a coefficient of 0.21 for carbonates (PAcorr2930 cm−1), which greatly improved relationships with Cmic, Nmic, CHWEand NHWE(R2= 0.68–0.75;P< 0.0001). We further developed a regression equation to correct PAnt2930 cm−1for future application using the relationship between PAnt713 cm−1(assigned for carbonates (mainly calcite)) and PA at 2930 cm−1(ΔPATIC2930 cm−1) (R2= 0.98). We concluded that PA 2930 cm−1has a high potential to be used as an indicator of SOM composition once carbonate interference is corrected for in carbonated containing soils. The proposed approach is free of multivariate calibration and the spectral index developed (PAcorr2930 cm−1) is suited to predict accurately labile SOM without the need of additional laboratory measurements. For general applicability of the approach, it should be tested on additional soil types of varying TOC and TIC contents.