We studied the effects of two percent by weight activated carbon versus biochar amendments in 93 cm long sand columns on the biofiltration of petroleum vapours released by a non-aqueous phase liquid (NAPL) source. Activated carbon greatly enhanced, whereas biochar slightly reduced, the biofiltration of volatile petroleum hydrocarbons (VPHs) over 430 days. Sorbent amendment benefitted the VPH biofiltration by retarding breakthrough during the biodegradation lag phase. Subsequently, sorbent amendment briefly reduced the mineralization of petroleum hydrocarbons by limiting their bioavailability. During the last and longest study period, when conditions became less supportive of microbial growth, because of inorganic nutrient scarcity, the sorbents again improved the pollution attenuation by preventing the degrading microorganisms from being overloaded with VPHs. A 16S rRNA gene based analysis showed sorbent amendment effects on soil microbial communities. Nocardioidaceae benefitted the most from petroleum hydrocarbons in activated carbon amended soil, whereas Pseudomonadacea predominated in unamended soil. Whilst the degrading microorganisms were overloaded with VPHs in the unamended soil, the reduced mobility and bioavailability of VPHs in the activated carbon amended soil led to the emergence of communities with higher specific substrate affinity, which removed bioavailable VPHs effectively at low concentrations. A numerical pollutant fate model reproduced these experimental observations by considering sorption effects on the pollutant migration and bioavailability for growth of VPH degrading biomass, which is limited by a maximum soil biomass carrying capacity. Activated carbon was a much stronger sorbent for VPHs than biochar, which explained the diverging effects of the two sorbents in this study.

中文翻译：

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活性炭和生物炭改性剂对土壤中石油蒸气生物过滤作用的不同机理

我们研究了2％重量的活性炭与93厘米长的砂柱中的生物炭修正物，用于对非水相液体（NAPL）源释放的石油蒸气进行生物过滤。活性碳在430天之内对挥发性石油烃（VPH）的生物过滤大大增强，而生物炭略有减少。吸收剂改性剂通过延迟生物降解滞后阶段的突破而使VPH生物过滤受益。随后，吸附剂改良剂通过限制其生物利用度而短暂地减少了石油烃的矿化作用。在最后也是最长的研究期间，由于无机营养物质的缺乏，当条件变得对微生物生长的支持减少时，吸附剂通过防止降解的微生物超载VPH而再次改善了污染衰减。活性炭改良土壤中的石油碳氢化合物对诺卡蝶科的影响最大，而假单胞菌科则为在未改良的土壤中占主导地位。在未改良的土壤中，降解微生物中的VPH含量超标，而在活性炭改良的土壤中，VPH的降低的迁移率和生物利用度导致出现了具有较高比底物亲和力的群落，从而有效地去除了低浓度的生物利用性VPH。数值污染物归因模型通过考虑吸附对污染物迁移和VPH降解生物量生长的生物利用度的吸附效应，再现了这些实验观察结果，VPH降解生物量的生长受到最大土壤生物量承载能力的限制。活性炭对VPH的吸附剂比生物炭强得多，这解释了本研究中两种吸附剂的发散作用。