Institute of Hydrogeology and Environmental Geology, Chinese Academy of Geological Sciences, Shijiazhuang, 050061, China; Key Laboratory of Groundwater Remediation of Hebei Province & China Geological Survey, Zhengding, 050083, China.
Frontiers Science Center for Deep-Time Digital Earth, Center for Geomicrobiology and Biogeochemistry Research, State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing, 100083, China.
Environ Pollut. 2024 Nov 15;361:124824. doi: 10.1016/j.envpol.2024.124824. Epub 2024 Aug 26.
Autotrophic microorganisms, the pivotal carbon fixers, exhibit a broad distribution across diverse environments, playing critical roles in the process of carbon sequestration. However, insights into their distribution characteristics in aquifers, particularly in those petroleum-hydrocarbon-contaminated (PHC) aquifers that were known for rich in heterotrophs, have been limited. In the study, groundwater samples were collected from red clay aquifers in the storage tank leakage area of a PHC site, a prevalent aquifer type in southern China and other regions. Metagenomics combined with hydrochemical and inorganic carbon isotope analyses were employed to elucidate the presence of microbial carbon fixation and its driving forces. Results showed that there were hundreds of autotrophic microorganisms participating in distinct carbon fixation processes in the red clay PHC aquifers. Reductive tricarboxylic acid (rTCA) and dicarboxylate/4-hydroxybutyrate (DC/4HB), as well as 3-hydroxypropionate (3HP or/and 3-hydroxypropionate/4-hydroxybutyrate (3HP/4HB)) were the predominant carbon fixation pathways. The abundances of carbon fixation genes and autotrophic microorganisms were significantly and positively correlated with hydrocarbon concentrations and δC of dissolved inorganic carbon (δC-DIC) values. This finding indicated that the petroleum hydrocarbon significantly promoted the proliferation of carbon fixation microorganisms, leading to a substantial uptake of inorganic carbon. Therefore, we deduce that this process holds considerable potential for carbon sequestration in PHC-contaminated aquifers.
自养微生物是重要的碳固定者，广泛分布于各种环境中，在碳封存过程中起着关键作用。然而，对于它们在含水层中的分布特征，特别是在那些以富含异养生物而闻名的石油烃污染（PHC）含水层中的分布特征，了解还很有限。在这项研究中，从 PHC 场地储油罐泄漏区的红土含水层中采集了地下水样本，这是中国南方和其他地区常见的含水层类型。采用宏基因组学结合水文地球化学和无机碳同位素分析的方法，阐明了微生物碳固定及其驱动因素的存在。结果表明，在红土 PHC 含水层中，有数百种自养微生物参与了不同的碳固定过程。还原三羧酸（rTCA）和二羧酸/4-羟基丁酸（DC/4HB）以及 3-羟基丙酸（3HP 或/和 3-羟基丙酸/4-羟基丁酸（3HP/4HB））是主要的碳固定途径。碳固定基因和自养微生物的丰度与烃浓度和溶解无机碳的δC 值（δC-DIC）呈显著正相关。这一发现表明，石油烃显著促进了碳固定微生物的增殖，导致大量无机碳的吸收。因此，我们推断，这一过程在 PHC 污染的含水层中具有相当大的碳封存潜力。
