The effective approaches to eliminate impacts of ethanol on the biodegradation of benzene, toluene, ethylbenzene, and xylene (BTEX) are concerned in the bioremediation of groundwater contaminated with ethanol-blended gasoline. In situ chemical oxidation (ISCO) is a common technique widely used for the remediation of contaminated groundwater. However, the selectivity of ISCO for BTEX and ethanol removal is poorly understood. Therefore, a batch experiment was performed with different aquifer materials, including calcareous soil, basalt soil, granite soil, dolomite, and sand. Gasoline was used to provide dissolved BTEX and ethanol reagent was used as additive to improve the quality of gasoline and to reduce the possibility of air pollution caused by gasoline. Persulfate (PS) was used as a chemical oxidant to oxidize organic contaminants. The target concentrations of BTEX and ethanol were 20 mg/L and 1000 mg/L, respectively. The results showed that ethanol could be preferentially degraded in the absence of PS and inhibit BTEX biodegradation. However, BTEX could be preferentially removed prior to ethanol in all aquifer materials used at ambient temperature, when PS was added at a PS/BTEX molar ratio of 150. Over 94% BTEX in sand, dolomite, and granite soil was preferentially removed with the first-order decay rate constants of 0.890–2.703 day⁻¹ within the first ~ 10 days, followed by calcareous and basalt soil at the constants of 0.123–0.371 day⁻¹. Ethanol could compete with BTEX for sulfate radical at the first-order decay rate constants of 0.005–0.060 day⁻¹ for the first 25 days, which was slower than that of BTEX. The pH quickly decreased to < 2.5 in dolomite, sand, and granite soil, but maintained > 6.2 in calcareous soil. Rich organic matter in calcareous and basalt soil had an inhibition effect on BTEX oxidation by PS. The pH buffer in calcareous soil may imply the potential of PS oxidation combined with bioremediation in carbonate rock regions.

Highly weathered acidic soils tend to have high phosphorus adsorption rates. Studying the differential phosphorus adsorption and desorption characteristics of these soils is of great significance to improve phosphorus utilization efficiency and reduce soil phosphorus loss in agricultural management. Erosive weathered granite soil (TL-Tillage layer, LL-Laterite layer, and SL-Sand layer) in Anji County, Zhejiang Province were selected for batch experiments and phosphorus fractionation test. The soil properties that are generally considered to have a greater impact on phosphorus adsorption and desorption are also studied. Derived from the Langmuir adsorption isotherm, the maximum absorption capacity (Qₘₐₓ) of phosphorus in TL soil was greater than that in LL and SL soil. With a pH of 4.3–5.0, the three soils have the most phosphorus adsorption. The desorption ratio (Dᵣ) in the SL soil is larger than the LL and TL soil. Six key soil property indicators can fit Qₘₐₓ and Dᵣ values well. Al-P is the main fraction in the phosphorus adsorption-desorption process. The particle size classification (PSC) method can be used to accurately calculate soil-specific surface area. The results of the soil phosphorus adsorption-desorption test can be used as an explanation of the results of artificial rainfall tests. Our results reveal the differential adsorption-desorption mechanism of eroded weathered granite soil, and provide a reference for selecting soil indicators for soil adsorption-desorption studies in different regions.