西藏当雄错盐湖是一个碱性的富锂、硼资源盐湖,对其碳酸盐沉积物的研究有助于了解盐湖形成过程中沉积环境的变化以及锂、硼资源的富集过程。为此,本文从当雄错盐湖碳酸盐剖面自上而下采集了31件样品。对这些样品开展了铀系年龄、XRD、主...西藏当雄错盐湖是一个碱性的富锂、硼资源盐湖,对其碳酸盐沉积物的研究有助于了解盐湖形成过程中沉积环境的变化以及锂、硼资源的富集过程。为此,本文从当雄错盐湖碳酸盐剖面自上而下采集了31件样品。对这些样品开展了铀系年龄、XRD、主-微量元素、碳-氧同位素测定以及介形类的鉴定分析。铀系年龄结果表明剖面沉积开始于(3788±120)a BP,结束于约2220 a BP。碳酸盐沉积的微量元素和稀土元素特征表明,其沉积水体为缺氧、还原环境下的咸水环境,沉积物形成于干旱、寒冷的气候环境,湖泊水体具有半开放-半封闭性质,但封闭程度较高。约3430 a BP时,当雄错水体盐度发生了较大改变。结合沉积物中介形类Candona gyrongensis的出现和沉积物的碳氧同位素特征,推测有地下淡水注入导致湖泊水体变淡和还原性减弱。当雄错水体的盐度在2220 a BP之前仍相对较低,湖水浓缩达到盐湖阶段的时间在2220 a BP以后。展开更多
受全球气候变暖的影响,青藏高原湖泊、河流的温度显著升高,水温变化与水生生物的繁育息息相关,但目前对于青海湖裸鲤洄游产卵的重要场所——河流入湖口的水温研究较少,水温变化对于裸鲤产卵的影响也尚不明确。因此本研究基于刚察气象站...受全球气候变暖的影响,青藏高原湖泊、河流的温度显著升高,水温变化与水生生物的繁育息息相关,但目前对于青海湖裸鲤洄游产卵的重要场所——河流入湖口的水温研究较少,水温变化对于裸鲤产卵的影响也尚不明确。因此本研究基于刚察气象站观测数据、中国区域地面气象要素驱动数据集(CMFD)、欧洲中期天气预报中心第五代陆面再分析数据集(ERA5-Land)、第六次国际耦合模式比较计划(CMIP6)的多模式数据,尝试利用Fresh water Lake Model(简称FLake模式)模拟青海湖最大支流布哈河入湖口处水温并评估其适用性,探讨了再分析数据和CMIP6多模式数据驱动模拟历史(1981—2014年)水温的集合的优越性,预估了未来时期(2024—2100年)三种情景下的水温演变及成因,结果表明:(1)CMFD和ERA5-Land模拟水温的集合优于单个模式的模拟水温且在短期和长期模拟结果精度都较好,CMIP6多模式长期的模拟水温集合优于单个模式的模拟水温,可以较好的再现再分析数据模拟水温的集合。(2)未来布哈河入湖口的水温随着排放强度的增加显著升高,与水温呈正相关的气象因子从大到小依次为气温、比湿、向下长波辐射和向下短波辐射,呈负相关的气象因子是风速;除远期高排放情景(SSP585)的向下短波辐射,其他情景的气象因子与水温的关系均通过了95%的显著性检验。(3)近期(2024—2040年),三种情景的水温较历史时期均有少许升高,水温间的差异不大,青海湖裸鲤产卵的窗口期略微缩短,水温升高会对裸鲤的产卵造成轻微影响;中期(2041—2060年),三种情景的水温进一步升高,水温间的差异逐渐显现,裸鲤的产卵窗口期明显缩短,水温升高对裸鲤的产卵有一定的危害;远期(2081—2100年),三种情景的水温差异更显著,SSP126和SSP245情景的升高速率减慢;SSP585情景的水温升高速率依旧加快,水温持续升高导致裸鲤的产卵窗口期显著缩短,一定程度限制了青海湖裸鲤的产卵活动。展开更多
The ice phenology of alpine lakes on the Tibetan Plateau(TP)is a rapid and direct responder to climate changes,and the variations in lake ice exhibit high temporal frequency characteristics.MODIS and passive microwave...The ice phenology of alpine lakes on the Tibetan Plateau(TP)is a rapid and direct responder to climate changes,and the variations in lake ice exhibit high temporal frequency characteristics.MODIS and passive microwave data are widely used to monitor lake ice changes with high temporal resolution.However,the low spatial resolutions make it difficult to effectively quantify the freeze-melt dynamics of lakes.This work used Sentinel-1 synthetic aperture radar(SAR)data to derive high-resolution ice maps(about 6 days),then with the aid of Sentinel-2 optical images to quantify freeze-melt processes in three typical lakes on the TP(e.g.Selin Co,Ayakekumu Lake,and Nam Co).The results showed that three lakes had an average annual ice period of 125-157 days and a complete ice cover period of 72-115 days,from 2018 to 2022.They exhibit different ice phenology patterns.Nam Co is characterized by repeated episodes of freezing,melting,and refreezing,resulting in a prolonged freeze-up period.Meanwhile,the break-up period of Nam Co lasts for a longer duration(about 19 days),and the break-up exhibits a smooth process.Similarly,Ayakekumu Lake showed more significant inter-annual fluctuations in the freeze-up period,with deviations of up to 28 days observed among different years.Compared to the other two lakes,Selin Co experienced a relatively short freeze-up and break-up period.In short,Sentinel-1 SAR data can effectively monitor the weekly and seasonal variations in lake ice on the TP.Particularly,this data facilitates quantification of the freeze-melt dynamics.展开更多
文摘西藏当雄错盐湖是一个碱性的富锂、硼资源盐湖,对其碳酸盐沉积物的研究有助于了解盐湖形成过程中沉积环境的变化以及锂、硼资源的富集过程。为此,本文从当雄错盐湖碳酸盐剖面自上而下采集了31件样品。对这些样品开展了铀系年龄、XRD、主-微量元素、碳-氧同位素测定以及介形类的鉴定分析。铀系年龄结果表明剖面沉积开始于(3788±120)a BP,结束于约2220 a BP。碳酸盐沉积的微量元素和稀土元素特征表明,其沉积水体为缺氧、还原环境下的咸水环境,沉积物形成于干旱、寒冷的气候环境,湖泊水体具有半开放-半封闭性质,但封闭程度较高。约3430 a BP时,当雄错水体盐度发生了较大改变。结合沉积物中介形类Candona gyrongensis的出现和沉积物的碳氧同位素特征,推测有地下淡水注入导致湖泊水体变淡和还原性减弱。当雄错水体的盐度在2220 a BP之前仍相对较低,湖水浓缩达到盐湖阶段的时间在2220 a BP以后。
文摘受全球气候变暖的影响,青藏高原湖泊、河流的温度显著升高,水温变化与水生生物的繁育息息相关,但目前对于青海湖裸鲤洄游产卵的重要场所——河流入湖口的水温研究较少,水温变化对于裸鲤产卵的影响也尚不明确。因此本研究基于刚察气象站观测数据、中国区域地面气象要素驱动数据集(CMFD)、欧洲中期天气预报中心第五代陆面再分析数据集(ERA5-Land)、第六次国际耦合模式比较计划(CMIP6)的多模式数据,尝试利用Fresh water Lake Model(简称FLake模式)模拟青海湖最大支流布哈河入湖口处水温并评估其适用性,探讨了再分析数据和CMIP6多模式数据驱动模拟历史(1981—2014年)水温的集合的优越性,预估了未来时期(2024—2100年)三种情景下的水温演变及成因,结果表明:(1)CMFD和ERA5-Land模拟水温的集合优于单个模式的模拟水温且在短期和长期模拟结果精度都较好,CMIP6多模式长期的模拟水温集合优于单个模式的模拟水温,可以较好的再现再分析数据模拟水温的集合。(2)未来布哈河入湖口的水温随着排放强度的增加显著升高,与水温呈正相关的气象因子从大到小依次为气温、比湿、向下长波辐射和向下短波辐射,呈负相关的气象因子是风速;除远期高排放情景(SSP585)的向下短波辐射,其他情景的气象因子与水温的关系均通过了95%的显著性检验。(3)近期(2024—2040年),三种情景的水温较历史时期均有少许升高,水温间的差异不大,青海湖裸鲤产卵的窗口期略微缩短,水温升高会对裸鲤的产卵造成轻微影响;中期(2041—2060年),三种情景的水温进一步升高,水温间的差异逐渐显现,裸鲤的产卵窗口期明显缩短,水温升高对裸鲤的产卵有一定的危害;远期(2081—2100年),三种情景的水温差异更显著,SSP126和SSP245情景的升高速率减慢;SSP585情景的水温升高速率依旧加快,水温持续升高导致裸鲤的产卵窗口期显著缩短,一定程度限制了青海湖裸鲤的产卵活动。
基金supported financially by the National Nature Science Foundation of China(No.41901129)the University Natural Sciences Research Project of Anhui Educational committee(KJ2020JD06)DUAN Zheng acknowledges the support from the Joint China-Sweden Mobility Grant funded by NSFC and STINT(CH2019-8250).
文摘The ice phenology of alpine lakes on the Tibetan Plateau(TP)is a rapid and direct responder to climate changes,and the variations in lake ice exhibit high temporal frequency characteristics.MODIS and passive microwave data are widely used to monitor lake ice changes with high temporal resolution.However,the low spatial resolutions make it difficult to effectively quantify the freeze-melt dynamics of lakes.This work used Sentinel-1 synthetic aperture radar(SAR)data to derive high-resolution ice maps(about 6 days),then with the aid of Sentinel-2 optical images to quantify freeze-melt processes in three typical lakes on the TP(e.g.Selin Co,Ayakekumu Lake,and Nam Co).The results showed that three lakes had an average annual ice period of 125-157 days and a complete ice cover period of 72-115 days,from 2018 to 2022.They exhibit different ice phenology patterns.Nam Co is characterized by repeated episodes of freezing,melting,and refreezing,resulting in a prolonged freeze-up period.Meanwhile,the break-up period of Nam Co lasts for a longer duration(about 19 days),and the break-up exhibits a smooth process.Similarly,Ayakekumu Lake showed more significant inter-annual fluctuations in the freeze-up period,with deviations of up to 28 days observed among different years.Compared to the other two lakes,Selin Co experienced a relatively short freeze-up and break-up period.In short,Sentinel-1 SAR data can effectively monitor the weekly and seasonal variations in lake ice on the TP.Particularly,this data facilitates quantification of the freeze-melt dynamics.