冻融对MNA技术修复石油污染土壤的影响

The Effect of Freezing and Thawing on the Remediation of Petroleum-contaminated Soil by MNA Technology

文章以实际污染土壤和模拟污染土壤为对象,研究了不同冻融循环次数(0、6、9、15、27次)、不同冷冻温度(-10、-20、-30℃)和不同土壤含水率(30%,50%,80%)条件下土壤团聚体组成、土壤酶活性和石油类浓度等参数变化。结果表明:(1)在相同含水率下,2种污染土壤都是随着冻融频次增加,>2 mm粒径团聚体比例显著减少,而0.25~2 mm粒径团聚体比例显著增加。土壤含水率增加至50%时,显著降低>2 mm粒径团聚体比例,提高0.25~2 mm和<0.25 mm粒径团聚体比例。(2)冻融作用对污染土壤中脲酶有促进作用、过氧化氢酶和脱氢酶有抑制作用,脲酶最多提高63.07%、过氧化氢酶活性最多降低了26.25%,脱氢酶降低了3.32%。(3)冻融前后实际污染土壤中烷烃降低1.87%,而模拟污染土壤中烷烃降低1.65%,去除效果不明显。冻融交替循环从根本上改变了土壤形态,有利于污染物在土壤中自然衰减,对石油污染土壤的自然及强化修复有效支撑。

Taking actual contaminated soil and simulated contaminated soil as objects,changes in parameters such as soil aggregate composition,soil enzyme activity and petroleum concentration under conditions of water content(30%,50%,80%),different freeze-thaw cycles(0,6,9,15,27),different freezing temperatures(-10℃,-20℃,-30℃)and different soils were studied.The results showed that under the same moisture content,with the increase of freeze-thaw frequency,the proportion of aggregates with a particle size of>2 mm decreased significantly,and the proportion of aggregates with a particle size of 0.25~2 mm increased significantly.When the soil moisture content increased to 50%,the proportion of aggregates with a particle size of>2 mm was significantly reduced,and the proportion of aggregates with a particle size of 0.25 to 2 and less than 0.25 mm was increased.Freezing and thawing can promote urease,catalase and dehydrogenase in contaminated soil.Urease can be increased by 63.07%,catalase activity by 26.25%,and dehydrogenase by 3.32%.Before and after freezing and thawing,the alkanes in the actual polluted soil decreased by 1.87%,while the alkanes in the simulated polluted soil decreased by 1.65%,and the removal effect was not obvious.The alternating freeze-thaw cycle fundamentally changes the shape of the soil,is conducive to the natural attenuation of pollutants in the soil,and effectively supports the natural and enhanced restoration of oil-contaminated soil.