SEASONALLY SATURATED SOILS IN THE PUGET LOWLAND II. MEASURING AND INTERPRETING REDOX POTENTIALS
SEASONALLY SATURATED SOILS IN THE PUGET LOWLAND II. MEASURING AND INTERPRETING REDOX POTENTIALS
复制标题
普吉特低地的季节性饱和土壤 II。
DOI：
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发表时间：
1992
期刊：
影响因子：
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通讯作者：
D. Carlson
中科院分区：
文献类型：
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作者：
C. Cogger;P. Kennedy;D. Carlson
氧化还原电位的测量可以提供洞察饱和度和颜色模式之间的关系，在季节性饱和土壤。然而，它们的价值是有限的，因为没有被广泛接受的方法来测量和解释现场氧化还原电位。我们进行这项研究，以确定哪些测量和解释方法是最适合在季节性饱和土壤的现场使用。氧化还原电极通过将Pt线焊接到Cu引线上、将结包封在丙烯酸管中并用环氧树脂密封来构造。在华盛顿西部的三个地点使用永久安装的土壤电极和一个地点使用临时安装的地下水电极测量氧化还原电位。氧化还原电位也在实验室土芯进行了测量，比较微观环境与电极差异对表观氧化还原变异性的影响。最后，交换性铁（II）测定在不同的氧化还原电位从土芯样品的提取物，以估计的氧化还原环境需要的发病铁还原和土壤斑驳的样品土壤。我们发现，适当构造的土壤电极响应氧化还原环境的变化，至少1年是可靠的。电极之间的变异性往往是大的变化或中间氧化还原环境，主要是由于在土壤中的微观差异。地下水的氧化还原测量值不大，因为我们研究的土壤中的浅层地下水通常是氧化的，即使土壤还原。地下水溶解O2与土壤氧化还原测量相结合，给出了土壤-地下水氧化还原环境的最完整的图片。在本研究的土壤中，交换性Fe（II）在≤+200 mV（pH 6-7）时存在，表明适合Fe还原和斑点的条件。
Redox potential measurements can provide insight into the relationships between saturation and color patterns in seasonally saturated soils. Their value is limited, however, because there are no widely accepted methods to measure and interpret field redox potentials. We conducted this research to determine which measurement and interpretation methods are most appropriate for field use in seasonally saturated soils. Redox electrodes were constructed by soldering Pt wire onto a Cu lead, encasing the junction in an acrylic tube, and sealing with epoxy. Redox potentials were measured at three sites in western Washington using permanently installed soil electrodes and at one site using temporarily installed ground water electrodes. Redox potentials were also measured in laboratory soil cores to compare the effects of microsite environments vs. electrode differences on apparent redox variability. Finally, exchangeable Fe(II) was measured in extracts from soil core samples at different redox potentials to estimate the redox environment needed for the onset of Fe reduction and soil mottling in the sample soils. We found that properly constructed soil electrodes responded to changes in the redox environment and were reliable for at least 1 year. Variability among electrodes was often large in changing or intermediate redox environments and was due primarily to microsite differences in the soil. Ground water redox measurements were of little value, because the shallow ground water in the soils we studied was generally oxidizing, even when the soil was reduced. Ground water dissolved O2 combined with soil redox measurements give the most complete picture of the soil-ground water redox environment. In the soils of this study, exchangeable Fe(II) was present at ≤+200 mV (pH 6–7) indicating conditions suitable for Fe reduction and mottling.