冬夏季温度和降水变化对青海湖全新世环境变化的影响初探
Seasonal Temperature and Precipitation Influenced Holocene Environmental Changes in Qinghai Lake,Northeastern Qinghai-Tibetan Plateau
投稿时间:2018-03-19  
DOI:10.12119/j.yhyj.201802003
中文关键词:  全新世  青海湖  青藏高原  季节温度和降水变化
英文关键词:Holocene  Qinghai Lake  Qinghai-Tibetan Plateau  Seasonal temperature and precipitation changes
基金项目:
作者单位
刘向军 中国科学院青海盐湖研究所,中国科学院盐湖资源综合高效利用重点实验室,青海西宁 810008
青海省盐湖地质与环境重点实验室,青海西宁 810008 
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中文摘要:
      青海湖是国内最大的内陆湖泊,位于青藏高原东北缘,因其处在东亚夏季风、印度季风和西风带的交替控制区域,对气候变化十分敏感,成为古环境变化研究的热点地区。有关青海湖的形成演化、环境变化和水文变化的研究也存在多种观点。本研究再分析了青海湖已报道的古环境指标和气候模式模拟的夏季、冬季温度和降水变化,力图更加全面地理解青海湖全新世以来的古环境变化。研究发现早全新世11~8 ka夏季降水量和表面蒸发量较大,冬季降水稀少,湖泊水位只有十余米深,使得青海湖周边风沙活动频繁。并且,早全新世的气候不稳定,经历了频繁和较大幅度的波动。全新世气候适宜期出现在8~6 ka,古环境指标指示这一时期为温暖湿润的气候环境,湖盆内植被以森林草原为主,湖泊水位不断上升。青海湖地区的夏季降水自6 ka开始减少,然而冬季降水增加,同时夏季温度和蒸发量减少,使得湖区植被组成由森林草原向高山草甸转变,湖区大范围形成古土壤。湖区古环境条件在晚全新世距今1.5 ka开始恶化,冬季和夏季降水同时减少,湖泊水位下降,风沙活动再次加强。
英文摘要:
      In the present paper,we reanalyzed the reported paleoenvironmental proxies,in combination with climate-model-simulated summer and winter temperature and precipitation changes,to more comprehensively understand paleoenvironmental changes in the Holocene period in Qinghai Lake. We found that the early Holocene (11-8 ka BP) summer precipitation and surface evaporation was high,but winter precipitation was low,causing widespread aeolian sands in the areas surrounding the lake and the lake water level only a few meters deep. Moreover,the early Holocene climate was not stable; it fluctuated frequently with large amplitudes. The Holocene hydrothermal configuration optimal period persisted from 8 ka to 6 ka BP,and some environmental proxies abruptly changed to indicate warm and wet environments during this period. The Asian summer monsoon weakened since 6 ka BP,while winter precipitation increased simultaneously,and summer temperature and evaporation decreased. These climate changes caused vegetation to transform from forest to grassland and alpine meadow,allowed the lake water level to be maintained at a high level,and caused continuous development of paleosol. Environmental conditions then deteriorated since 1.5 ka BP,summer and winter precipitation over Qinghai Lake declined simultaneously,the lake level dropped,and aeolian activities intensified again.
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