多年冻土区热融湖塘演化及其环境效应研究进展

Research progress on the evolution and environmental effects of thermokarst lakes in permafrost regions

近几十年随着全球气候变暖及人类活动的增强,冻土退化趋势显著,这一过程改变了寒区的水文地质条件,从而引起一系列的生态环境变化。热融湖塘是冻土退化的产物,其形成与发展又会引起冻土环境的改变,进而对全球气候变化产生影响。因此,针对多年冻土退化过程中日趋严重的热喀斯特现象,以及由此而产生的冻土融穿、地下水位改变、热融湖塘扩张等问题,对目前多年冻土区热融湖塘的水文变化研究现状进行分析整理。本文主要从以下五个方面展开了论述:(1)热融湖塘演化过程及主要影响因素分析;(2)热融湖塘水文过程时空变化规律及影响因素分析;(3)热融湖塘水量平衡过程研究及影响因素;(4)热融湖塘变化对区域水质的影响;(5)热融湖塘对碳循环的影响。最后,提出在后期研究中应基于同位素技术,充分考虑湖塘周边环境,并结合气候变化、多年冻土退化状况进行多因素分析,以期能为深入开展研究冻土退化背景下冻土水文过程、区域水资源演变以及对生态环境的影响提供参考依据。

In recent decades,with the global warming and the enhancement of human activities,the trend of per-mafrost degradation is significant.This process changes the hydrogeological conditions of the cold region,thus causing a series of ecological environment changes.Thermokarst lakes are the product of permafrost degradation and active thermokarst lakes indicate the decrease of permafrost stability.Thermokarst lakes are also a major source of greenhouse gases,which are important in the carbon cycle in cold regions.The formation and develop-ment of thermokarst lakes will cause the change of frozen soil environment,which will affect the global climate change.Therefore,in view of the increasingly serious thermokarst phenomenon in the process of permafrost deg-radation,and the resulting problems such as permafrost thawing penetration,groundwater level change,thermo-karst lake expansion and so on,the current research status of the hydrology change of thermokarst lake in perma-frost area is analyzed and sorted out.This paper mainly discusses from the following five aspects:(1)Analysis of the main factors of the formation and evolution of the thermokarst lake;(2)Analysis of temporal and spatial variation of thermokarst lake hydrological process and its influencing factors;(3)Thermokarst lake water bal-ance process and influencing factors;(4)Influence of thermokarst lake changes on regional water quality;(5)Influence of thermokarst lake on carbon cycle.Finally,the main problems in the field of thermokarst lakes are discussed:there are some defects in the identification of thermokarst lakes;the factors related to the area change of thermokarst lake are single.There is still a gap in understanding the broader relationship between permafrost gradient,permafrost degradation,and the corresponding hydrological response of thermokarst lakes.Knowl-edge of the effects of permafrost degradation on lake water chemistry is limited.Based on the existing problems,it is proposed that isotope technology should be used to fully consider the surrounding environment of the pond in the later research,and multi-factor analysis should be carried out in combination with climate change and perma-frost degradation,in order to provide reference for further research on the frozen soil hydrological process,re-gional water resources evolution and the impact on the ecological environment under the background of perma-frost degradation.