Abstract

A number of soils and parent rocks at different stages of weathering were investigated for the formation of heterogeneous wettability under residual hydrophobic contamination in situ. The aim of the study was to determine specific wetting contact angles of soils and parent rocks under different conditions. The wetting contact angle was measured by the captive bubble method, which implied attaching an air bubble to the specially prepared horizontal surface of a water-placed specimen with subsequent measuring the wetting contact angle according to the profile of the bubble’s photo. The soil specimens were artificially hydrophobized using media containing less than 1 wt % of oil degradation products with adapted microflora. Leached chernozem, alluvial silty loam, bentonite, dolomite–clayey marl, ornamental marl, and phyllite were studied. Based on the Pearson’s goodness-of-fit criterion, good angular data approximation by both the von Mises–Tikhonov distribution and the normal distribution was found. The dependence of the types and parameters of statistical distributions of the wetting contact angle on hydrophobization conditions of the specimens was revealed. The formation of the specimens’ hydrophobicity exclusively under introduced organic matter and incomplete water saturation conditions was found; at the same time, a high heterogeneity of wettability and hydrophobic areas at wetting contact angles above 129° was manifested. The results of the study can be useful for assessing and predicting the impact of soil hydrophobic contaminants and amendments, as well as for advancing methods for determining the wetting contact angle on the soil surface.

中文翻译：

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疏水化土壤和母岩润湿接触角的不均匀性

摘要

研究了风化不同阶段的许多土壤和母岩在原位残留疏水污染下形成异质润湿性。该研究的目的是确定不同条件下土壤和母岩的特定润湿接触角。润湿接触角是通过捕获气泡法测量的，这意味着将气泡附着在水放置样品的特殊准备的水平表面上，然后根据气泡照片的轮廓测量润湿接触角。使用含有少于 1 wt% 的具有适应微生物区系的油降解产物的介质对土壤样品进行人工疏水化。研究了浸出的黑钙土、冲积粉质壤土、膨润土、白云石-粘土泥灰岩、观赏性泥灰岩和千枚岩。基于 Pearson 的拟合优度标准，通过 von Mises-Tikhonov 分布和正态分布找到了良好的角度数据逼近。揭示了润湿接触角统计分布的类型和参数对样品疏水化条件的依赖性。发现仅在引入有机物和不完全水饱和条件下形成样品的疏水性；同时，在润湿接触角大于 129° 时，润湿性和疏水区域的高度不均匀性被证明。该研究的结果可用于评估和预测土壤疏水性污染物和改良剂的影响，以及用于确定土壤表面润湿接触角的先进方法。