涪陵焦石坝页岩气开采区土地损毁的生态风险评价

Ecological risk assessment of land destruction by shale gas development at Fuling Jiaoshiba,China

页岩气在勘探、开采、集输过程中对周边生态系统会产生直接或间接影响。通过构建页岩气开采土地损毁生态风险因果链识别井场、运输道路及集输管线等风险源,基于最小阻力模型定量分析土地损毁的生态累积影响;选取了植被覆盖度、生态服务价值及土壤肥力等因子表征区域生态重要性,土壤侵蚀度、石漠化敏感性及水环境敏感性等表征生态脆弱性,综合评价区域生态敏感度,并以此为风险受体,实现涪陵焦石坝页岩气开发区的生态风险评价。2012—2015年末,涪陵焦石坝页岩气产建区钻井数量快速增加,分布广,页岩气开发对区域生态累积影响扩大。2015年末,区域一半以上面积为中、高生态风险区(146.56km^2,55.8%),主要分布于南部乌江河谷及北部低山区,前者水环境敏感度高,后者岩溶发育度高,土壤侵蚀度高,石漠化敏感;该区域内大规模页岩气开发将面临水环境污染、生境破坏、土壤退化、石漠化加重及生物多样性减少等生态风险,是生态环境管理及风险防范的重点方面。研究结果可为区域生态安全建设提供科学的参考。

Regional ecosystems can be impacted, directly or indirectly, by exploration, extraction, collection, and transportation of shale gas. By establishing an ecological risk cause-effect chain based on land destruction caused by shale gas development at Fuling Jiaoshiba, China, well sites, transportation roads, and pipe lines were identified as risk sources. On the basis of a minimum resistance model, the cumulative ecological impacts of land destruction were quantitatively analyzed. Vegetation coverage, ecosystem service value, and soil fertility were then selected as the characteristics of important ecological value, and soil erosion, stony desertification sensitivity, and aquatic environment sensitivity were selected as indices of ecological vulnerability. By synthesizing important ecological value and ecological vulnerability indices, the regional ecological sensitivity was evaluated. By combining the cumulative ecological impacts with regional ecological sensitivity, an assessment of regional ecological risk was carried out. In the period 2012 to 2015, there were a large number of shale gas drilling wells scattered across the Fuling Jiaoshiba region at Chongqing, China, and the cumulative ecological impact of shale gas development was very significant. By the end of 2015, more than half of the region was classified as areas of middle or high ecological risk （146.56 km2, 55.8%）. These areas were mainly located in the southern Wujiang River Valley and the northern low mountain region. The southern Wujiang River Valley is a highly sensitive aquatic environment, whereas the northern low mountain region is highly sensitive to soil erosion and Karst rocky desertification. With the progression of shale gas development, the region will be exposed to water pollution, habitat destruction, soil degradation, aggravated rocky desertification, loss of biodiversity, and other ecological risks, which are key aspects of ecological environment management and risk prevention. These results provide references for development of ecological security measures for shale gas development at Fuling Jiaoshiba, China.