酸性土壤中亚硝态氮提取方法的改进
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S151.9

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国家自然科学基金项目(41330744)资助。


Improving Extraction Method in Determining NO2--N in Acidic Soil
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    摘要:

    亚硝态氮(NO2--N)是土壤硝化和反硝化过程中很重要的一种中间产物,与土壤中含氮气体的产生密切相关。NO2--N在土壤中的转化极其迅速,尤其在强酸性条件下NO2--N极不稳定,2 mol/L KCl溶液提取过程中会大量发生分解。为了更准确地研究酸性土壤中的NO2--N变化,必须选择合适的提取剂,以实现土壤中NO2--N的高效提取。本文采用15N标记方法,系统比较了不同方法提取土壤NO2--N和NH4+-N 的回收率,提出了改进措施。结果显示:调节强酸性土壤初始pH为6.0和8.0处理,经2 mol/L KCl溶液提取,提取液的pH分别保持在4.8和5.8左右,显著高于对照(3.8)。pH与振荡时间对酸性土壤NO2--N和NH4+-N的回收率存在显著的交互影响。振荡时间30 min以内,pH 6.0和pH 8.0处理,NO2--N的回收率最高;而振荡时间为30 min时,未调节pH和pH 6.0处理NH4+-N的回收率最高。综合考虑,提取土壤无机氮时,土壤/KCl悬浮液的pH保持在5.0 ~ 6.0,振荡时间30 min,能同时满足对土壤NO2--N和NH4+-N的提取。对于强酸性土壤(pH<6.0),本研究推荐使用KCl溶液和pH 8.4的缓冲液混合溶液(KCl溶液/缓冲液比为4/1)作为提取液(土/液比为1/5)。对于pH在7.5以上的土壤样品,推荐使用KCl溶液和pH 7.5的缓冲液混合溶液(KCl溶液/缓冲液比为4/1)作为提取液(土/液比为1/5)。对于pH在6.0 ~ 7.5的土壤样品,可以直接使用2 mol/L KCl溶液提取。

    Abstract:

    Nitrite (NO2--N) is a key intermediate in both nitrification and denitrification, which is also closely related to the emission of nitrogen gas from soil. Since its rapid reaction in soil and instability in acidic condition, a large number of decomposition will occur in the extraction process using 2 mol/L KCl. In order to enhance the accuracy of study on NO2--N changes in the acidic soil, a more appropriate extraction method should be investigated to improve the effeciency of the nitrite extraction. In this study, we put forward some suggestions in improving NO2--N extraction based our resutls of NO2--N recovery measured by using 15N-labelling method. The results showed that pH and shaking time could both significantly affect the recovery of NO2--N and NH44+-N in acidic soils. Within 30 min shaking, the recovery of NO2--N was highest in the adjusted pH 6.0 and pH 8.0 treatments, while the recovery of ammonium was highest in the unadjusted and adjusted pH 6.0 treatments. In addition, even after shaking, the pH of extraction solution in the adjusted pH 6.0 and pH 8.0 treatments were maintained at about 4.8 and 5.8, respectively, which were significantly higher than that of control (3.8). In all, the pH of extraction solution should be adjusted to 5.0–6.0 and shaking time should be 30 min to get a more efficient extraction of both NO2--N and NH4+-N. For strongly acidic soils (pH<6.0), a mixture of KCl and pH 8.4 buffer (KCl︰buffer = 4︰1) should be used as extraction solution (the ratio of soil to extraction solution was 1︰5). For alkaline soils (pH≥7.5), a mixture of KCl and pH 7.5 buffer (KCl︰buffer = 4︰1) should be used as extraction solution (the ratio of soil to extraction solution was 1︰5). For the soil samples with pH ranged from 6.0 to 7.5, it can be extracted directly by 2 mol/L KCl solution.

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引用本文

戴沈艳,温 腾,张金波,蔡祖聪.酸性土壤中亚硝态氮提取方法的改进[J].土壤,2018,50(2):341-346. DAI Shenyan, WEN Teng, ZHANG Jinbo, CAI Zucong. Improving Extraction Method in Determining NO2--N in Acidic Soil[J]. Soils,2018,50(2):341-346

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历史
  • 收稿日期:2017-03-15
  • 最后修改日期:2017-05-01
  • 录用日期:2017-05-02
  • 在线发布日期: 2018-04-04
  • 出版日期: 2018-04-25