Isotopes in groundwater (~2H, ~(18)O,~(14)C) revealed the climate and groundwater recharge in the Northern China

摘要

We collected 3275 sets of delta D and delta O-18 and 1451 C-14 data of groundwater in 14 basins or plains in the Northern China from the published sources in an attempt to investigate the isotopic characteristics of groundwater and their possible link with groundwater recharge and modem and past climate conditions in regional scales. The results showed that the deuterium excess of groundwater in the Monsoon regions were generally lower than that in the Westerly regions in the Northern China, reflecting the influences of different vapor sources and transmission modes. The delta D and delta O-18 in groundwater lied closely to the Asian summer monsoon limit (ASML) were affected by both the Asian monsoon and Westerlies. The delta D and delta O-18 of groundwater exhibited obvious latitude effect in the monsoon region, while it seemed to be dominated by the continental and elevation effects in the Westerly region both in the late Pleistocene and the Holocene. Based on the isotopic proxy records of climates, the depletion in O-18 and D of the groundwater recharged in last glacial period in the late Pleistocene was observed which indicated that it was cooler especially in the Last Glacial Maximum (LGM), while the O-18 and D were enriched in groundwater recharged in the Holocene. The transition from the late Pleistocene to Holocene was characterized by higher frequency fluctuation of delta O-18 in the groundwater, probably suggesting that the climatic conditions were unstable. The groundwater recharge could be roughly divided into three main periods under relative warm and humid climates. The variation of regional climate was one of the driving forces for the recharge and regeneration of groundwater. Our results may enhance the understanding of groundwater recharge and its connection with the climate changes in the regional scales. (C) 2019 Elsevier B.V. All rights reserved.