环渤海沿岸沼泽化、盐渍化和沙漠化的演化及其与全球变化的关系

THE EVOLUTIONAL TREND OF SWAMPING,SALTING AND DESERTIZATION ALONG THE COAST OF BOHAI SEA AND ITS RELATIONSHIP TO GLOBAL CHANGE

渤海沿岸广泛分布有沼泽化、盐渍化和沙漠化现象。本区在20000—12000aB.P.为干旱期,沙漠化呈正向过程;12000—2500aB.P.为暖湿期,沼泽化呈正向过程;2500aB.P.至今为向干冷转化期,湖沼迅速消失,盐渍化由发展转向减轻—脱盐,沙漠化则日趋严重。特别是近100年来其趋势更为明显和严重,成为本区环境恶化的主要方面。这种变化主要受气候和地质环境变化所控制。作者根据地质历史时期三化现象的演替规律,预测演化趋势,并研究其与全球变化的关系。

Swamping,salting and desertization are the reflection of surficial ecological environ-ment change in various geological and geomorphological regions due to the periodic changeof climatic factors.They are the results of the two forward and inverse contrary processes of cli-matic change,while there are close relationship among them,which is shown in the processesof interaction of atmosphere,lithosphere,hydrosphere and biosphere.Bohai Sea is an inland sea formed during Cenozoic,and the coast around it,where thehydrosphere,atmosphere,lithosphere and biosphere meet,is an ideal region with a favourablegeological environment suitable for habitation and living of human being.This region is alsoa sensitive zone for environment change.On the other hand,it has quite a few unfavourablegeological factors and various geological hazards that frequently occurred.Swamping,saltingand desertization are just among them.The evolutional alternation of these three hazards hasexisted during the geological period.In recent 100 years,especially the last 50 years,the swamp-ing was quickly shrunk and desertification was getting more and more serious,having be-come one of the serious problems of worsen environment in this region.This change is mainlycontrolled by climate,groundwater and impact of human engineering activities.Among them,the periodic change of climate is the decisive factor for the alternation and evolution of thethree above-mentioned hazards,while the groundwater is the major factor controlling the ari-dity and humidity of soil or surficial sediments and height,concentration and chemical comp-osition of salt carried by the groundwater,and the human engineering activities could exert tre-mendous influence on soil,surficial sedimentary and ecological environment.Although thehuman activities may be the decisive factor in a certain region,it is difficult after all totransform the universal periodic change,especially the regularity of periodic climatic change.The paper focuses on the distribution regularity,forming mechanism and influence factorsof land swamping,salting and desertification along the coastal region of Bohai Sea,in orderto study their evolution tendency,then to discuss the environmental change and its tendency,further more,to approach their relationship with global change on this aspect.