Table 2.

Evaluation index system for environmental risks and environmental impacts of CO₂ geological storage.

Class	Content	Environment elements	Description
Prohibited index	Surface water	Surface water	Rivers and lakes.
	Protection area of centralized drinking water resources	Groundwater	According to national centralized drinking water resources, the maximum radius (10000 m) of the second protected areas was adopted, which listed in Technical Guideline for Delineating Source Water Protection Areas (HJ/T338-2007), as groundwater resources protection area in this research.
	Nature reserve (national and provincial)	Important vegetation, key species	All lands, land waters and sea areas where representative natural ecosystems, the naturally concentrated distribution of rare and endangered native wildlife species and nature relics with special meaning and other protective objects located on, are required to set aside special area for protection and management according to relevant law and regulations.
	National forest park	Important vegetation, key species	Forest landscape with beautiful scenery, the area with concentrated humanities, high ornamental value, high scientific value, and high cultural values, special geographical site, regional representation, sound tourism service facilities, high visibility, and the area convenient for people to visit, rest or carry out scientific, cultural and educational activities.
	National park of China	Important vegetation, key species	Natural landscape and human landscape can reflect important natural change process and major historical and cultural development process. The area basically keeps in a natural state or historical original appearance with national representative characteristics.
Restricted index	National key ecological function areas (national main function zoning)	Ecological patch, ecological function areas	The national main function zoning is a strategic planning, space layout and binding plan for China’s national territorial spatial development. This plan puts forward clear requirements in different economic and social activities for China. The national key ecological function areas are important regions for maintaining regional ecological security pattern, biodiversity, realizing a virtuous circle and sustainable utilization of wildlife resources, protecting the natural ecological system and habitat of important species.
	National ecological function zoning	Important ecological function areas	National ecological function zoning is based on regional ecosystem, ecological sensitivity and ecological service function of spatial distribution pattern, and divided area into different ecological function regions. National ecological function zoning has defined the concept of national important ecological function areas which plays an important role in guiding the site selection of CO2 geological storage. The two areas of water conservation and biodiversity conservation in national key ecological function zoning are most sensitive relative to geological storage project.
	Net Primary Productivity (NPP)	Land vegetation	NPP represents the active degree of land vegetation.
	Population	Human health	To use LandScan data (http://web.ornl.gov/sci/landscan/landscan_data_avail.shtml). LandScan global population dataset was developed by U.S. Department of Energy’s Oak Ridge National Laboratory (ORNL), which is the most accurate and reliable around the world. It has a distribution model and the best resolution of global dynamic statistical analysis. LandScan population data is an accepted standard by U.S. Department of Defense and the State Department to assess population risk.
	Population activity intensity	Human health	To use big data with spatial information from Weibo Blog. 1 km grid spatial distribution of population data is assumed that people basically do not move, so the affected population can be assessed based on specific population density. However, human movement and activity capacity are very strong, even if their residences (based on demographic and census) are fixed. It is likely that most of the time they are engaged in activities in other area.