Polluted soils in temperate regions are frequently exposed to seasonal freezing and thawing events during which the soil biological properties are expected to change in response to the associated temperature variations. In this study, we investigated the influence of freeze–thaw events on enzymatic activities and natural attenuation of petroleum hydrocarbons in temperate soils with varying pollution profiles. Four soils [clean natural, Diesel amended (DAS), Crude-oil amended (COAS), and aged oil polluted] were subjected to ten freeze–thaw temperature regimes ranging from − 20 to + 20 °C for 45 days. The soil enzymatic activities and fractional petroleum hydrocarbon analysis were conducted using spectrophotometry and gas chromatography–mass spectrometry, respectively. After the incubation period, freezing resulted in decreased enzyme (lipase and dehydrogenase) activities in both clean and polluted soils, while thawing events compensated for the enzymatic losses that occurred during the preceding freezing phase. Fractional hydrocarbon analysis revealed that there was a switch from active removal of light- to medium-chain hydrocarbons (C10–C23) in the short-term polluted soils (DAS and COAS) during the freezing phase to rapid degradation of the heavier nonvolatile hydrocarbon fractions (C23–C34) during the thawing phase, and the long-term polluted soil had lower hydrocarbon removal rates than the short-term polluted soils. The relationship between the natural attenuation of hydrocarbons in the oil polluted soils and incubation temperatures was linear in the short- and long-term petroleum polluted soils.

温带地区的污染土壤经常暴露于季节性冻结和解冻事件，在此期间，土壤生物学特性有望响应相关的温度变化而发生变化。在这项研究中，我们研究了冻融事件对温带土壤（具有不同污染特征）中酶活性和石油碳氢化合物自然衰减的影响。对四种土壤[清洁的天然，柴油修正（DAS），原油修正（COAS）和受污染的老化油]进行了十次冻融温度测试，温度范围为− 20至+ 20°C，持续45天。用分光光度法和气相色谱-质谱法分别进行土壤酶活性和石油烃馏分分析。潜伏期过后，冷冻导致清洁和污染土壤中的酶（脂肪酶和脱氢酶）活性降低，而解冻事件补偿了先前冷冻阶段发生的酶损失。分数碳氢化合物分析显示，在冷冻阶段，从短期污染土壤（DAS和COAS）的主动去除轻链到中链碳氢化合物（C10–C23）转变为较重的非挥发性碳氢化合物组分的快速降解（C23–C34）在融化阶段，长期污染土壤的烃去除率低于短期污染土壤。在短期和长期的石油污染土壤中，油污染土壤中碳氢化合物的自然衰减与孵化温度之间的关系是线性的。