Seasonal frozen soil accounts for about 53.50%of the land area in China.Frozen soil is a complex multiphase system where ice,water,soil,and air coexist.The distribution and migration of salts in frozen soil during soi...Seasonal frozen soil accounts for about 53.50%of the land area in China.Frozen soil is a complex multiphase system where ice,water,soil,and air coexist.The distribution and migration of salts in frozen soil during soil freezing are notably different from those in unfrozen soil areas.However,little knowledge is available about the process and mechanisms of salt migration in frozen soil.This study explores the mechanisms of salt migration at the ice-liquid interface during the freezing of pore fluids through batch experiments.The results are as follows.The solute concentrations of liquid and solid phases at the ice-liquid interface(C*_(L),C*_(S))gradually increased at the initial stage of freezing and remained approximately constant at the middle stage.As the ice-liquid interface advanced toward the system boundary,the diffusion of the liquid phase was blocked but the ice phase continued rejecting salts.As a result,C*_(L)and C*_(S)rapidly increased at the final stage of freezing.The distribution characteristics of solutes in ice and the liquid phases before C*_(L)and C*_(S)became steady were mainly affected by the freezing temperature,initial concentrations,and particle-size distribution of media(quartz sand and kaolin).In detail,the lower the freezing temperature and the better the particle-size distribution of media,the higher the solute proportion in the ice phase at the initial stage of freezing.Meanwhile,the increase in concentration first promoted but then inhibited the increase of solutes in the ice phase.These results have insights and scientific significance for the tackling of climate change,the environmental protection of groundwater and soil,and infrastructure protection such as roads,among other things.展开更多
Eclogite is first discovered from Qiang- tang area, central Tibet, which occurs as a lens in the high-pressure metamorphic belt comprising glauco- phane-muscovite schist and garnet-muscovite schist, along the south ma...Eclogite is first discovered from Qiang- tang area, central Tibet, which occurs as a lens in the high-pressure metamorphic belt comprising glauco- phane-muscovite schist and garnet-muscovite schist, along the south margin of Lungmu Co-Shuanghu Paleo-Tethys suture. A glaucophane 40Ar/39Ar age of 220 Ma and a phengite 40Ar/39Ar age of 221.9 Ma have been obtained from blueschists associated with eclogite. The rock consists of garnet, omphacite, amphibole, phengite, and rutile, etc, and the jadeite content in omphacite ranges from 32.7% to 38.95%. It is estimated that the temperature of the eclogite is <500℃ and pressure varies in the range of 1.56― 2.35 GPa. The discovery of Qiangtang ecologite fur- ther supports that there is a suture zone of Indo- Chinese epoch in central Qiangtang area, and is very important for discssing the evolution of the pa- leo-ocean and paleo-plate tectonics in this area.展开更多
基金This research was financially supported by the National Natural Science Foundation of China(41572225)project of China Geological Survey(DD20189662,DD20211256).
文摘Seasonal frozen soil accounts for about 53.50%of the land area in China.Frozen soil is a complex multiphase system where ice,water,soil,and air coexist.The distribution and migration of salts in frozen soil during soil freezing are notably different from those in unfrozen soil areas.However,little knowledge is available about the process and mechanisms of salt migration in frozen soil.This study explores the mechanisms of salt migration at the ice-liquid interface during the freezing of pore fluids through batch experiments.The results are as follows.The solute concentrations of liquid and solid phases at the ice-liquid interface(C*_(L),C*_(S))gradually increased at the initial stage of freezing and remained approximately constant at the middle stage.As the ice-liquid interface advanced toward the system boundary,the diffusion of the liquid phase was blocked but the ice phase continued rejecting salts.As a result,C*_(L)and C*_(S)rapidly increased at the final stage of freezing.The distribution characteristics of solutes in ice and the liquid phases before C*_(L)and C*_(S)became steady were mainly affected by the freezing temperature,initial concentrations,and particle-size distribution of media(quartz sand and kaolin).In detail,the lower the freezing temperature and the better the particle-size distribution of media,the higher the solute proportion in the ice phase at the initial stage of freezing.Meanwhile,the increase in concentration first promoted but then inhibited the increase of solutes in the ice phase.These results have insights and scientific significance for the tackling of climate change,the environmental protection of groundwater and soil,and infrastructure protection such as roads,among other things.
文摘Eclogite is first discovered from Qiang- tang area, central Tibet, which occurs as a lens in the high-pressure metamorphic belt comprising glauco- phane-muscovite schist and garnet-muscovite schist, along the south margin of Lungmu Co-Shuanghu Paleo-Tethys suture. A glaucophane 40Ar/39Ar age of 220 Ma and a phengite 40Ar/39Ar age of 221.9 Ma have been obtained from blueschists associated with eclogite. The rock consists of garnet, omphacite, amphibole, phengite, and rutile, etc, and the jadeite content in omphacite ranges from 32.7% to 38.95%. It is estimated that the temperature of the eclogite is <500℃ and pressure varies in the range of 1.56― 2.35 GPa. The discovery of Qiangtang ecologite fur- ther supports that there is a suture zone of Indo- Chinese epoch in central Qiangtang area, and is very important for discssing the evolution of the pa- leo-ocean and paleo-plate tectonics in this area.
