Sookhak Lari Kaveh, Davis Greg B, Bastow Trevor, Rayner John L
CSIRO Environment, Private Bag No. 5, Wembley, WA 6913, Australia; School of Engineering, Edith Cowan University, 270 Joondalup Drive, Joondalup, WA 6027, Australia; Geothermal Energy and Geofluids Group, Department of Earth Sciences, ETH Zurich, CH-8092, Zurich, Switzerland.
CSIRO Environment, Private Bag No. 5, Wembley, WA 6913, Australia.
Sci Total Environ. 2024 Jan 10;907:168039. doi: 10.1016/j.scitotenv.2023.168039. Epub 2023 Oct 23.
Petroleum releases into the subsurface contribute to global soil carbon emissions. Quantifying releases and changes in releases of carbon from soils over the lifetime of a spill is complex. Natural source zone depletion (NSZD) of light non-aqueous phase liquids (LNAPLs) embodies all key mechanisms for transformation to carbon gases and their release from soils including partitioning, transport and degradation of petroleum components. Quantification of the interconnected behaviours of the soil microbiome, fluid flow, multi-component transport, partitioning, and biodegradation is crucial for understanding NSZD. Volatilization from LNAPL, aerobic biodegradation, methanogenesis, and heat production all lead to release of greenhouse gases to the atmosphere. To estimate carbon emissions, using a validated computational platform, we modelled the long term NSZD of four petroleum hydrocarbon types; crude oil, diesel, jet fuel and gasoline, to span the major products used globally. For two soil types, we estimated 150 years of carbon emissions from annual minor and 25 mostly major petroleum hydrocarbon land release incidents since 1950 - with an estimated released mass of ~9 million tonnes across the circumstances considered. Up to 2100 the mass of carbon emitted to the atmosphere is estimated to range from 4 to 6 Teragrams, with nearly 60 % currently released. Nomographs generated help predict the fate of LNAPL plumes and carbon emissions due to NSZD, which is crucially important to management of soil and groundwater contamination. The method provides a basis to include additionally identified and future petroleum releases. It is noted that the petroleum mixture composition, degradation rates, volatilization, and subsurface characteristics all can influence carbon emission estimations.
石油泄漏到地下会导致全球土壤碳排放。量化泄漏事件整个生命周期内土壤中碳的释放量及其变化是复杂的。轻质非水相液体（LNAPL）的自然源区耗竭（NSZD）体现了转化为碳气体并从土壤中释放的所有关键机制，包括石油成分的分配、运输和降解。量化土壤微生物群落、流体流动、多组分传输、分配和生物降解的相互关联行为对于理解NSZD至关重要。LNAPL的挥发、好氧生物降解、甲烷生成和产热都会导致温室气体释放到大气中。为了估算碳排放，我们使用一个经过验证的计算平台，对四种石油烃类型（原油、柴油、喷气燃料和汽油）的长期NSZD进行了建模，以涵盖全球使用的主要产品。对于两种土壤类型，我们估算了自1950年以来每年少量以及25起大多为大量的石油烃陆地泄漏事件150年的碳排放量——在所考虑的情况下，估计释放质量约为900万吨。到2100年，估计排放到大气中的碳质量在4至6太克之间，目前已释放近60%。生成的列线图有助于预测LNAPL羽流的归宿以及NSZD导致的碳排放，这对于土壤和地下水污染的管理至关重要。该方法为纳入额外识别的和未来的石油泄漏提供了基础。需要注意的是，石油混合物组成、降解速率、挥发和地下特征都会影响碳排放估算。
