Potential impacts of CO2 leakage from the CCS sites on seed germination and soil microbial enzyme activities

Abstract:

To ensure the safety of carbon capture and storage (CCS) technology, it is essential to assess the impacts of potential CO₂ leakage on the soil and ecosystem. The changes in soil environment due to the CO₂ leakage might have an enormous effect on the plant growth. As a preliminary study, we conducted a research focusing on the germination process because it is known to be especially sensitive to the environmental change. The objective of this study is to investigate the impacts of high soil CO₂ concentration on the germination of different species. A laboratory experiment was designed to investigate the effect of high soil CO₂ concentration on germination rate and soil physicochemical/microbial parameters. Cabbage, corn, bean, and wheat were selected for this study. The concentrations of the injected CO₂ treatments were 10%, 30%, 60% and 100%, and the actual soil CO₂ concentration ranged from 3.6% to 53.2%. Two types of controls were employed: the one connected with ambient air tank and the other connected with nothing. The final germination rates of four crops were not different between the controls and 10% treatment, but the delay of germination was observed in cabbage, corn, and bean. At 30% treatment, the germination rates of cabbage, corn and bean were 38%, while that of wheat was 78%. No seed was germinated at 60% and 100% treatments. After the incubation, soil pH decreased from 6.0 in the controls to 5.6 in the 100% treatment. The contents of soil total C and total N were not different among treatments. Activities of microbial fluorescein diacetate hydrolysis were not different among treatments for all plants. Five kinds of soil extracellular enzyme activities were not affected by the CO₂ treatments. Our results suggest that: 1) Soil CO₂ concentration at 3-4% did not inhibit germination of four crops. 2) Wheat is most resistant to high soil CO₂ concentration in this study. 3) Soil microbial parameters were more tolerant during the short term injection.