Table 1.

Main environmental elements impacted by CO₂ geological storage.

Environmental elements	Negative impact	Fatal or serious impact
Groundwater and Surface Water	Low acidity would be caused at 0.2~2% concentration of CO2, but it will not make a significant difference; If CO2 concentration >2%, it will cause moderate acidity and corrosion.	If CO2 concentration >6%, it will lead to an increased acidity, enhanced corrosion and loss of irrigation effect.
Vegetation	If CO2 concentration >5%, it will have a detrimental effect on plant health and yield; Concentration of 5–30% will have a serious impact.	If CO2 in the soil gas exceeds over 20% in the long term (weeks or months), it will lead to dead zones, and no naked eye visible plants survived. More than 30% are considered fatal levels of plant life.
Human Health	1–3% CO2 concentration will cause shortness of breath, headaches and sweating, which will appear a physiological adaptation without negative effects; 3–5% CO2 concentration will cause shortness of breath, high blood pressure and some discomfort. CO2 concentration >5% will lead to physical and mental harm, and loss of consciousness.	CO2 concentration >10% would lead to severe symptoms, including rapid loss of consciousness, coma or death may. If exposure to such an environment in a long time, CO2 concentration exceed 25–30% will lead to loss of consciousness or even lead to respiratory arrest and death.