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作 者 ：苏冬雪;王文杰*;邱岭;王洪岩;安静;郑广宇

期 刊 ：植物研究 2012年 32卷 (3)期 页码：348-353

关键词：土壤溶液吸光度值；可溶性碳；可溶性氮；土壤全碳；土壤全氮；

Keywords:soil solution absorbance value, soil dissolved organic carbon, soil dissolved organic nitrogen, soil organic carbon, soil organic nitrogen,

摘 要 ：通过4个土壤深度100个样品14个波长（250、254、260、265、272、280、285、300、340、350、365、400、436和465 nm）土壤溶液吸光度值和土壤碳（可溶性碳DOC、全碳SOC）、土壤氮（可溶性氮DON、全氮SON）的测定，旨在探讨土壤溶液吸光度指示土壤碳氮指标的可行性及土壤深度对其可能影响。结论如下：（1）表层土壤和深层土壤吸光度值均随波长增加而指数下降，但表层土壤吸光度值较高，下降速度较快，较低波长更有利于区分表层和深层土壤溶液吸光度差异；和深层土壤相比，表层0~20 cm土壤SOC、DON和SON与不同波长吸光度有更好的相关性，但DOC与不同波长吸光度的相关性表层和深层差异较小；（2）250~300 nm的8个吸光度值具有高度相关性，它们在分析土壤溶液吸光度变化时具有等效性；基于所有数据的拟合分析发现，低波长（如254 nm）吸光度与土壤SOC、DON和SON相关性最高(R²=0.53~0.59)，而更高波长（340 nm及以上）相关性明显降低。但DOC与254、340、365和400 nm吸光度相关性相差不大（R²=0.25~0.33）。这些发现说明，土壤溶液吸光度值，特别是低波长（250～300 nm）可以表征落叶松林土壤碳、氮相关指标的变化，但是需要考虑不同碳氮指标以及不同土层之间的差异。

Abstract:Based on 100 samples from 4 soil depths, the spectrophotometric absorbances of soil solutions at 14 wavelengths (250, 254, 260, 265, 272, 280, 285, 300, 340, 350, 365, 400, 436 and 465 nm) and soil carbons (dissolved organic carbon DOC and soil organic carbon SOC）and nitrogens (dissolved soil nitrogen DON and soil organic nitrogen SON) were concurrently measured. We are aiming to answer the question that absorbance at which wavelength is most correlated with the soil carbon and nitrogen, and whether or not differences exist in these relations between top- and sub-soils. The following conclusions were obtained. Firstly, although absorbance values of surface and deep soil solutions significantly decreased with wavelength, the decrease in top soil was much steeper than that in sub-soils. The lower region of the studied wavelengths was more powerful to distinguish the difference between surface and deep soils, accordingly. Comparing with deep layers, more robust correlations between soil solution absorbance and SOC, DON and SON were found in surface soil layer (0-20 cm). However, the difference in the DOC and absorbance relations between surface and deep soils was much weaker. Secondly, the absorbance values of 8 wavelengths (250-300 nm) were significantly auto-correlated, indicating that each of them could function the same in characterizing soil solution. Using 254 nm as a representative of them, the regression analysis between absorbance (254, 340, 365, 400, 436 and 465 nm) and soil carbon, nitrogen have been carried out by using the entire pooled data. The best regressions (R²=0.53-0.59) for SOC, DON, SON were found in 254 nm, and sharp decreases in R² value with wavelength increases were found. No such large change was found in DOC, and R² from 0.25 to 0.33 were found in wavelengths of 254, 340, 365 and 400 nm. Our findings indicate that the spectrophotometric absorbance of soil solution (particularly from 250 nm to 300 nm) can be used as indicators for monitoring soil carbon and nitrogen changes, and attention should be paid to the soil sampling depths and variation in different soil carbon and nitrogen parameters.

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