Bathroom-rich greywater coming directly in contact with virgin soil for years contaminates soil and alters its properties. The degree of alteration of soil properties may also depend on geological settings from which the soil was formed. The present study was designed to investigate the physico-chemical and geotechnical properties of greywater-contaminated soil (GCS) in different soils of basement complex formation. Soil samples were collected from greywater discharge zones and control soil (CS) in two locations (Mapo in Ibadan, Oyo State and Isolu in Abeokuta, Ogun State, Nigeria) at the depths of 0.5, 1.0 and 1.5 m from the surface, and the soil properties were analysed following standard procedures in the laboratory. The experiment consists of two modes: CS with no presence of greywater and GCS. The results of this study showed that alteration of most analysed properties depends greatly on sampling depth. There is increased in soil pH, cation exchange capacity, dry density (DD), saturated hydraulic conductivity (K_sat) and shear strength (SS) in GCS at Mapo over their control values, while porosity, Atterberg limits (ALs), plasticity index and moisture content (MC) were reduced relative to the CS at all sampling depths. However, only bearing ratio improved at each sampling depth in GCS at Isolu, while alterations in other analysed properties did not follow clear trend. Correlation coefficient showed positive correlation between % clay and AL, porosity and ALs; MC and ALs at 1% level, while negative correlation exists between DD and ALs, % sand and ALs as well as K_sat and ALs at the two locations. Two-way ANOVA showed that there is a significant difference at 5% level (p < 0.05) based on sampling depths for most analysed properties except SS, organic matter and soil resistivity. Further investigation is needed to study the trend of alteration of soil properties with depth on GCS at other soil types and geological formations.

中文翻译：

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尼日利亚西南部地下复杂地区长期受灰水污染的土壤的岩土和理化性质评估

富含浴室的灰色水直接与原生土壤接触多年，污染了土壤并改变了土壤的特性。土壤性质的变化程度也可能取决于形成土壤的地质环境。本研究旨在调查在地下室复合体形成的不同土壤中受灰水污染的土壤（GCS）的物理化学和岩土特性。从灰水排放区和对照土壤（CS）的两个位置（距地面0.5、1.0和1.5 m的深度）分别从两个地点（奥约州伊巴丹的Mapo和尼日利亚奥贡州阿贝库塔的Isolu）收集土壤样品。在实验室中按照标准程序分析土壤性质。实验包括两种模式：不存在灰水的CS和GCS。这项研究的结果表明，大多数分析属性的改变很大程度上取决于采样深度。土壤的pH值，阳离子交换能力，干密度（DD），饱和水力传导率（在麻坡，GCS中的GCS中的K _sat）和抗剪强度（SS）超过了它们的控制值，而在所有采样深度下，相对于CS而言，孔隙率，Atterberg极限（ALs），可塑性指数和水分含量（MC）均降低了。但是，在Isolu的GCS的每个采样深度，只有承载比有所改善，而其他分析属性的变化没有遵循明显的趋势。相关系数表明％粘土与AL，孔隙率和ALs呈正相关；MC和ALs处于1％的水平，而DD和ALs，％沙子和ALs以及两个位置的K _sat和ALs之间存在负相关。双向方差分析表明，在5％的水平上存在显着差异（p <0.05），基于除SS，有机物和土壤电阻率以外的大多数分析特性的采样深度。在其他土壤类型和地质构造下，需要进一步调查以研究土壤性质随GCS深度变化的趋势。