Direct expression of an index for the degree of humification of humic acids using organic carbon concentration
Direct expression of an index for the degree of humification of humic acids using organic carbon concentration
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DOI：
10.1080/00380768.2003.10409978
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发表时间：
2003-02
影响因子：
2
通讯作者：
K. Ikeya;A. Watanabe
中科院分区：
文献类型：
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作者：
K. Ikeya;A. Watanabe
摘要 腐殖酸腐殖化程度的指标之一 RF，以有机 C 浓度来评价。对 36 个腐殖化程度不同的腐殖酸样品进行了分析，比较了腐殖酸溶液消耗的 0.02 M KMnO4 的体积，并使用溶解 C 分析仪测定了其有机 C 浓度。无论腐殖化程度如何，它们之间都发现显着相关性（r = 0.981***），并且 RF 可以用 A 600/C 代替，A 600/C 是 0.1 M NaOH 中每 mg C mL−1 在 600 nm 处的吸光度，乘以系数 0.0648（r = 0.994***）。通过与干燃烧法测定的C含量进行比较，确认了使用溶解C分析仪测定的腐植酸溶液的有机C浓度的准确性。尽管以重铬酸钾-硫酸为试剂的比色法估算的腐植酸溶液中的有机C浓度明显低于使用溶解C分析仪测定的浓度，但它们之间的高度相关性（r = 0.918***）使得能够通过比色法估算A 600/C。在 A 600/C-log (A 400/A 600) (= Δlog K) 图中，可以应用 A 600/C 值 2.5 和 5.0 代替 RF 值 40 和 80 作为边界，将腐植酸分类为 IYPes A、B 和 Rp。还发现 E 4/E 6 （在 0.025 M NaHCO3 中运行的 465 和 665 处的吸光度比）与 A 400/A 600 或 Δlog K 之间存在显着相关性，但含有高比例 Pg（绿色级分）的样品除外，这表明它们之间的互换性例外。还使用四种典型的日本土壤检验了在不改变数量和质量的情况下缩短提取腐殖酸和黄腐酸部分的时间。将现有 NAGOYA 方法（Kuwatsuka et al. 1992: Soil Sci. Plant Nutr., 38, 23–30）中的静置和间歇振荡用 0.1 M NaOH 在 25°C 下振荡 48 小时的提取修改为在相同条件下连续振荡，从而将提取时间缩短至 24 小时。对于含有低腐殖化程度的腐殖酸的 Fluvisol，4 小时 16 小时（过夜）的较短时间被认为是不够的。
Abstract One of the indices for the degree of humification of humic acids, RF, was evaluated in terms of organic C concentration. Thirty-six humic acid samples varying in the degree of humification were analyzed for comparison of the volumes of 0.02 M KMnO4 consumed by humic acid solutions, with their organic C concentration determined using a dissolved C analyzer. A significant correlation (r = 0.981***) was found between them regardless of the degree of humrncation, and RF could be replaced with A 600/C, the absorbance at 600 nm per mg C mL−1 in 0.1 M NaOH, by multiplying by a factor of 0.0648 (r = 0.994***). Accuracy of the organic C concentration of the humic acid solution that was determined using the dissolved C analyzer was confirmed by comparing with the C content determined by the dry-combustion method. Although the organic C concentrations in the humic acid solutions estimated by a colorimetric method with potassium dichromate-sulfuric acid as reagent were significantly lower than those determined using the dissolved C analyzer, the high correlation between them (r = 0.918***) enabled to estimate A 600/C by the colorimetry. In the A 600/C-log (A 400/A 600) (= Δlog K) diagram, A 600/C values of 2.5 and 5.0 could be applied instead of RF values of 40 and 80 as boarders to classify humic acids into lYPes A, B, and Rp. Significant correlations were also found between E 4/E 6 , the ratio of absorbances at 465 and 665 run in 0.025 M NaHC03 , and A 400/A 600 or Δlog K except for a sample containing a high proportion of Pg, the green fraction, which indicated the interchangeability between them with exception. Shortening of the period for extracting humic and fulvic acid fractions without changes in quantity and quality was also examined using four typical Japanese soils. Modification of extraction with standing and intermittent shaking with 0.1 M NaOH at 25°C for 48 h in the present NAGOYA method (Kuwatsuka et al. 1992: Soil Sci. Plant Nutr., 38, 23–30) to continuous shaking under the same conditions enabled to shorten the period of extraction to 24 h. Shorter periods of 4 hand 16 h (overnight) were considered to be insufficient for a Fluvisol containing humic acids with a low degree of humification.