| "Global change"and "terrestrial hydrologic cycle"are the key problems of many resent earth scientific research programs, which require interdisciplinary and collaboration with other fields. Scientists mainly study these problems from ocean, land and atmosphere. The studies, however, are paid less attention to groundwater in the hydrologic chain from ocean—atmosphere —surface water and groundwater —ocean. In fact, groundwater that distributes widely in terrestrial area, as an important part of hydrologic cycle, plays an important role on mass and energy transfer among spheres, and is the potential achievement which can directly store the information of environmental change. Thus, groundwater provides an unique information carriers for studying the global change and terrestrial hydrologic cycle. Taken groundwater as information carriers of ancient geological environment changes, the purposes of present work are to establish aquifer archive, reconstruct the processes of groundwater resource formation and evolution, provide a new information source for study of global change and terrestrial cycle, and guide to groundwater resource sustainable development. This paper focus on three problems: (1) identify the information of paleoclimate from groundwater system in the North China Plain (2) understand groundwater evolution and its response to climatic change during the past 30,000 years in the North China Plain; ( 3 ) discuss the attribute of groundwater resource in deep confined aquifer for groundwater sustainable development. The present work regarded the regional groundwater system as an unity of subsystems, which are connected by isotopes in hydrological cycles. Quantity and quality studies are carried out by comprehensive analysis methods. Taken the North China Plain as a case study area, selected isotopic compositions in groundwater as paleoenvironmental indicators, the groundwater formation and evolution on regional and time scale are studied by using hydrogeochemistry, isotopic hydrogeology and paleohydrogeology methods on the basis of plenty of information stored in groundwater. In the study, the groundwater stratification in spatial and time is considered. Meanwhile, the features of current groundwater system circulation are regarded as the basic insight into groundwater evolution. By establishing groundwater cross section of age sequence and analyzing the paleoenvironmental parameters, the pattern of regionalgroundwater evolution over the last 30,000 years has been established. Furthermore, the attribute of groundwater in deep confined aquifer also has been redefined. The following results are obtained from the present study. 1. Establish the 14C-age cross section for groundwater in deep confined aquifer, the North China Plain. Along the groundwater flow path of Taihang mountains —Shijiazhuang —Hengshui—Cangzhou—Bohai Sea, the 14C ages of groundwater increase from modern to 30kaB.P.. Therefore, groundwater samples in different location represent different time, and compose a groundwater ages sequence section like stratum sequence. 14C age for groundwater west from Shulu is younger than 10kaB.P., while it ranges between 1 0—2 5 kaB.P in east from Shulu. They reflects that groundwater in deep confined aquifer was recharged at different periods during the past 30ka. Groundwater system with different 14C age is the information carriers of paleoenvironment. 2. Establish the paleoclimatic archive over the past 30,000 years and 300 years from deep confined aquifer and unsaturated zone profile, respectively. The δ18O and δD plot against 14C ages for deep confined aquifer in the North China Plain show that two distinct stage of δ18O and δD, respectively. The δ18O and δD value of groundwater with 14C ages from 30 ka B.P to 10 ka B.P. was lighter than those of groundwater with 14C ages younger than 10 kaB.P.. The heavier and lighter δ18O and δD stages are corresponding to the isotope stage 1 and stage 2 of deep sea sedimentary core, respectively. The observed shift to lighter isotopic content during the Pleistocene is consistent with a decrease in the mean annual temperature, reflected that the climate in late Pleistocene was colder than that in Holocene. 30 ka B.P—13 ka B.P., δ18O and δD values are relatively light, implied that this period was the last glacial period and the climate was cold. The lightest δ18O value at about 18kaBP and δD at 17kaB.P. reflect the last glacial maximum (LGM) which extent to 15kaB.P.. The mean surface air temperature calculated by isotopes was 4 ℃in the last glacial maximum, which was cooled by 6 ℃to 9 ℃. 13kaB.P. —11kaB.P., the δ18O and δD values increased with fluctuation and reached the highest of the glacial period at about 11kaB.P. , indicating the unstable climate in the transition from last glacial period to Holocene. The glacial climate tendedto end after 15kaB.P. 11kaB.P. —present, the δ18O and δD values were significant heavier than that in the last glacial period, reflecting that climate in this period was warmer. The amount effect of isotope, however, suppresses the temperature effect because of prevailing summer monsoon. From 8ka B.P. to 5ka B.P, the δ18O and δD of groundwater showed relative low value over the Holocene, probably indicated a prevailing summer monsoon situation, warmer climate and increase in rainfall. In contrast, higher δ18O and δD value after 5kaB.P. corresponded to weak summer monsoon period, cool climate and decrease in rainfall. The changes of δ13C value in the groundwater over the last 30kaB.P. indicate that no substantially changes in vegetation cover. In this case, δ13C values reflected the changes of rainfall and temperature. The δ13C values are depleted during 11 —13kaB.P. and indicate the cold climate and lack of rainfall. Contrary, the relative enriched δ13C values indicated the warm, humid climate and increasing rainfall. Cl concentration in groundwater will be controlled by the climatic conditions. The relative high chloride value from 30kaB.P. to 10kaB.P. suggested that the climate was arid and rainfalls reduction in the last glacial maximum. Conversely, low chloride concentration from 10kaB.P. to present showed that the climate humid and rainfall increased, especially in Holocene climatic optimum from 8kaB.P. to 5 kaB.P.. Two chloride profiles of unsaturated zone at piedmont plain of Taihang Mountains suggested that there are three climatic cycles showing the cold-dry or wet-warm conditions over the psat 300 years. The wet-warm periods were 1702—1725A.D., 1761—1825A.D., 1876—1892A.D., respectively. 3. The groundwater evolution was characterized by periodicity and gradual and sudden change over the last 30,000 years. It has a close relationship with paleoclimatic and paleoenvironmental changes. The statistic frequency of 14C ages for 149 groundwater samples indicated that groundwater recharge mainly occurred before 20 kaB.P., and the period of 105.5 kaB.P.. Groundwater evolution in late Pleistocene was influenced by precipitation which was controlled by temperature changes, while it changed to be influenced by precipitation which was controlled by the rising of summer monsoon during Holocene. The isotopic records of groundwater shows different climatic change from that in the North Europe. This reflects the particularity of groundwater formation and evolution in North China Plain. Groundwater recharge in Holocene showed that continually recharged from 11kaB.P. to 6kaB.P. with maximum at about 6kaB.P. After this period, rechargealternatively occurred and significant recharge was at about 4kaB.P. , which corresponded to pluvial and arid periods The chloride concentration of soil water in northern Shangdong revealed that chloride accumulated from 4kaB.P and reach to peak value at about 3kaB.P.. Then it decreased and extended to present day. This indicated that there was a hiatus in recharge under arid condition at 3kaB.P.. In addition, another chloride top front occurred from about 8kaB.P. to 6kaB.P., this accumulation in recharge episode probably reflected the dissolution of soil salt by infiltrated water. Therefore, except for the influence of sea level change in littoral plain, the salinity of groundwater in North China Plain originated from dissolution of soil salt and intensive evaporation. The arid climate from 3kaB.P. was responsible for shallow saline groundwater. This has been supported by 14C age about 31kaB.P. for groundwater within the depth of 70m. This result reflects the sudden change of groundwater evolution. Groundwater evolution in North China Plain was characterized by periodically obtaining recharge water from precipitation during the past 300 years. The recharge period and recharge hiatus alternatively changed and corresponded to the climatic changes. Compared to recharge hiatus, the recharge periods were temporary. This suggested that recharge during the past 300 years was relative small on the time scale of 30,000 years. The recharge rate estimated were 1 0 —2 0 mm/a during the recharge period and 3 —7 mm/a during non-recharge period over the past 300 years. 4. Simulated the responses of groundwater evolution to paleoclimatic changes during the Holocene. Numerical modeling results implied that groundwater evolution depended on the paleoclimatic changes. In natural state, groundwater flow direction has no significant change. The hydraulic gradient tends to decrease from early Holocene to present. Groundwater evolution could be classified into three stages since 12kaB.P.. Stage 1 is early Holocene ( 1 2 —8 kaB.P.) In this period, climate was cold and arid. Precipitation was lower than the average annual precipitation. Groundwater table was at deep depth. Stage 2 is middle Holocene (8 kaB.P.—3.1 kaB.P.). Climate was warm and humid. Precipitation was higher than the average annual precipitation. Groundwater table fluctuated at very shallow depth. In this period, most part of the study area were surface water and marsh. Stage 3 is late Holocene (3.1 kaB.P.—present). Climate was temperate and slight dry. Precipitation fluctuated at the average annual precipitation. Groundwater table changed at a level higher than that of stage 1. 5. Groundwater resource in deep confined aquifers could be regarded as...
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