[Objective] This study aimed to investigate the dominant populations of late-summer phytoplankton and conduct comprehensive nutritional evaluation of water quality in Bailang Lake. [Method] A series of water quality s...[Objective] This study aimed to investigate the dominant populations of late-summer phytoplankton and conduct comprehensive nutritional evaluation of water quality in Bailang Lake. [Method] A series of water quality survey and phytoplankton sampling was conducted in Bailang Lake in September 2011, a total of four sam- pling points were set, to detect and analyze the total nitrogen, total phosphorus, ammonia nitrogen, nitrite nitrogen, nitrate nitrogen and permanganate index in water samples and further conduct comprehensive nutritional evaluation of the water quality factors using comprehensive nutritional state index method. [Result] Water in Bailang Lake was neutral to slightly alkaline with pH of 8.57. The average water trans- parency was 0.4 m, with relatively high content of dissolved oxygen. The content of total nitrogen was relatively high of 3.043 mg/L averagely. Comprehensive nutritional evaluation showed that the water quality of Bailang Lake belonged to moderate eu- trophication. As can be seen from various comprehensive nutritional state indices TLI, the contribution of transparency, chlorophyll a and total nitrogen to the eutrophi- cation in Bailang Lake was the greatest, followed by the permanganate index and total phosphorus. Statistical analysis showed that the average weight-biomass of phy- toplankton in Bailang Lake was 6.442 mg/L, and the average was 146.46x104 individuals/ml. There were eight dominant species in Bailang Lake, including Scenedesmus, Tetraedron, Merismopedia sinica, Phormidium, Merismopedia, Tribonema, Chroomonas and Synedra. [Conclusion] This study provided data informa- tion for the environmental protection and fisheries production in Bailang Lake.展开更多
The clinopyroxene amphibolite from the Bailang terrane is located in the central section of the Yarlung Zangbo suture zone(YZSZ),southern Tibet.The study of it is expected to provide important clues for the subduction...The clinopyroxene amphibolite from the Bailang terrane is located in the central section of the Yarlung Zangbo suture zone(YZSZ),southern Tibet.The study of it is expected to provide important clues for the subduction of the Neo-Tethyan Ocean below the Asian Plate and thus for better understanding of the development of the India-Asia collision zone.Based on integrated textural,mineral compositional,metamorphic reaction history and geothermobarometric studies of the clinopyroxene amphibolite within a serpentinite mélange,four overprinted metamorphic stages are established.They are the first metamorphic record of M1 stage indicated by a relict assemblage of plagioclase+clinopyroxene+amphibole,an early M2 stage characterized by an assemblage of medium-grained clinopyroxene+amphibole+plagioclase+quartz as well as rutile inclusion in titanite,which is formed during burial process,an isobaric cooling M3 stage which is characterized by an assemblage of clinopyroxene+amphibole+plagioclase+titanite,and a decomposing retrograde stage M4,which is represented by the amphibolite+plagioclase symplectite+titanite+rutile+quartz.By applying the THERMOCALC(versions 6.2 and 6.3)technique in the NCFMASHTO system,the P-T conditions estimated from M1 to M4 stages are ca.8.6 kbar/880℃,10.8–13.4 kbar/800–840℃,12.7–13.2 kbar/650–660℃ and<11.2 kbar/640℃,respectively.The mineral assemblages and their P-T conditions define a counterclockwise P-T path for the clinopyroxene amphibolite of the Xigaze ophiolite,suggesting that the rocks underwent a cooling process during burial from magmatic protolith,and a decompressing stage after the pressure peak metamorphic conditions,which implies that the Bailang terrane of the Xigaze ophiolite may have experienced subduction/collision-related tectonic processes.The peak metamorphism reaches to the transitional P-T conditions among amphibolite facies,granulite facies and eclogite facies with a burial depth of 30–40 km.After exhumation of the ophiolitic unit to the shallow crustal levels,the clinopyroxene amphibolite exposes to a high fO2 condition on the basis of the stable epidotebearing assemblage in the T-MO2 diagrams.A late subgreenschist facies overprinting subsequently occurs,the relevant mineral assemblage is prehnite+albite+chlorite+epidote+quartz.展开更多
近年来,作者在横断山脉三江并流区开展历史堵江滑坡调查,在金沙江上游发现系列沿江分布的残碉,其中以左岸的白玉县卓英村残碉分布最为集中,共17座,且未见公开报道。这些残碉是一个历史部落或村庄的遗迹,是藏彝走廊历史文化遗存的组成部...近年来,作者在横断山脉三江并流区开展历史堵江滑坡调查,在金沙江上游发现系列沿江分布的残碉,其中以左岸的白玉县卓英村残碉分布最为集中,共17座,且未见公开报道。这些残碉是一个历史部落或村庄的遗迹,是藏彝走廊历史文化遗存的组成部分。鉴于藏彝走廊研究主要集中在社会科学方面,本文尝试采用自然科学方法拓展相关研究。基于现场调查和地质测年,结合前人工作成果,确定残碉群的建造时间与历史归属,分析历史滑坡堵江事件对河流地貌与河谷文明演变的影响。结果表明:1)卓英村残碉群兴建于1780~1490 a BP,相应的历史年代为东汉末期至南朝时期,按地域极有可能是古白狼国遗迹;2)残碉的修建高程和时间与措拉古滑坡堰塞湖尾部的湖滩高程和溃决时间等具有较好的一致性,湖泊淤积、干热河谷气候、取水便利等为卓英村的兴起奠定了基础;3)约1510 a BP前的一次大洪水事件导致措拉堰塞坝完全溃决,岸坡塌岸引起的耕地逐渐消失,以及取水不便等人居环境恶化是导致卓英村被遗弃的自然因素;4)横断山脉河流历史堵江滑坡引起的河道淤积为民族迁徙提供了良好的通道,也留存了丰富的历史遗迹,类似卓英村残碉的深入研究有望丰富和拓展白狼国与藏彝走廊的研究内容。展开更多
基金Supported by Science and Technology Project in Anhui Province(11070303016)~~
文摘[Objective] This study aimed to investigate the dominant populations of late-summer phytoplankton and conduct comprehensive nutritional evaluation of water quality in Bailang Lake. [Method] A series of water quality survey and phytoplankton sampling was conducted in Bailang Lake in September 2011, a total of four sam- pling points were set, to detect and analyze the total nitrogen, total phosphorus, ammonia nitrogen, nitrite nitrogen, nitrate nitrogen and permanganate index in water samples and further conduct comprehensive nutritional evaluation of the water quality factors using comprehensive nutritional state index method. [Result] Water in Bailang Lake was neutral to slightly alkaline with pH of 8.57. The average water trans- parency was 0.4 m, with relatively high content of dissolved oxygen. The content of total nitrogen was relatively high of 3.043 mg/L averagely. Comprehensive nutritional evaluation showed that the water quality of Bailang Lake belonged to moderate eu- trophication. As can be seen from various comprehensive nutritional state indices TLI, the contribution of transparency, chlorophyll a and total nitrogen to the eutrophi- cation in Bailang Lake was the greatest, followed by the permanganate index and total phosphorus. Statistical analysis showed that the average weight-biomass of phy- toplankton in Bailang Lake was 6.442 mg/L, and the average was 146.46x104 individuals/ml. There were eight dominant species in Bailang Lake, including Scenedesmus, Tetraedron, Merismopedia sinica, Phormidium, Merismopedia, Tribonema, Chroomonas and Synedra. [Conclusion] This study provided data informa- tion for the environmental protection and fisheries production in Bailang Lake.
基金financially supported by the National Natural Science Foundation of China (No. 41572044)the SDUST Research Fund (No. 2015TDJH101)
文摘The clinopyroxene amphibolite from the Bailang terrane is located in the central section of the Yarlung Zangbo suture zone(YZSZ),southern Tibet.The study of it is expected to provide important clues for the subduction of the Neo-Tethyan Ocean below the Asian Plate and thus for better understanding of the development of the India-Asia collision zone.Based on integrated textural,mineral compositional,metamorphic reaction history and geothermobarometric studies of the clinopyroxene amphibolite within a serpentinite mélange,four overprinted metamorphic stages are established.They are the first metamorphic record of M1 stage indicated by a relict assemblage of plagioclase+clinopyroxene+amphibole,an early M2 stage characterized by an assemblage of medium-grained clinopyroxene+amphibole+plagioclase+quartz as well as rutile inclusion in titanite,which is formed during burial process,an isobaric cooling M3 stage which is characterized by an assemblage of clinopyroxene+amphibole+plagioclase+titanite,and a decomposing retrograde stage M4,which is represented by the amphibolite+plagioclase symplectite+titanite+rutile+quartz.By applying the THERMOCALC(versions 6.2 and 6.3)technique in the NCFMASHTO system,the P-T conditions estimated from M1 to M4 stages are ca.8.6 kbar/880℃,10.8–13.4 kbar/800–840℃,12.7–13.2 kbar/650–660℃ and<11.2 kbar/640℃,respectively.The mineral assemblages and their P-T conditions define a counterclockwise P-T path for the clinopyroxene amphibolite of the Xigaze ophiolite,suggesting that the rocks underwent a cooling process during burial from magmatic protolith,and a decompressing stage after the pressure peak metamorphic conditions,which implies that the Bailang terrane of the Xigaze ophiolite may have experienced subduction/collision-related tectonic processes.The peak metamorphism reaches to the transitional P-T conditions among amphibolite facies,granulite facies and eclogite facies with a burial depth of 30–40 km.After exhumation of the ophiolitic unit to the shallow crustal levels,the clinopyroxene amphibolite exposes to a high fO2 condition on the basis of the stable epidotebearing assemblage in the T-MO2 diagrams.A late subgreenschist facies overprinting subsequently occurs,the relevant mineral assemblage is prehnite+albite+chlorite+epidote+quartz.
文摘近年来,作者在横断山脉三江并流区开展历史堵江滑坡调查,在金沙江上游发现系列沿江分布的残碉,其中以左岸的白玉县卓英村残碉分布最为集中,共17座,且未见公开报道。这些残碉是一个历史部落或村庄的遗迹,是藏彝走廊历史文化遗存的组成部分。鉴于藏彝走廊研究主要集中在社会科学方面,本文尝试采用自然科学方法拓展相关研究。基于现场调查和地质测年,结合前人工作成果,确定残碉群的建造时间与历史归属,分析历史滑坡堵江事件对河流地貌与河谷文明演变的影响。结果表明:1)卓英村残碉群兴建于1780~1490 a BP,相应的历史年代为东汉末期至南朝时期,按地域极有可能是古白狼国遗迹;2)残碉的修建高程和时间与措拉古滑坡堰塞湖尾部的湖滩高程和溃决时间等具有较好的一致性,湖泊淤积、干热河谷气候、取水便利等为卓英村的兴起奠定了基础;3)约1510 a BP前的一次大洪水事件导致措拉堰塞坝完全溃决,岸坡塌岸引起的耕地逐渐消失,以及取水不便等人居环境恶化是导致卓英村被遗弃的自然因素;4)横断山脉河流历史堵江滑坡引起的河道淤积为民族迁徙提供了良好的通道,也留存了丰富的历史遗迹,类似卓英村残碉的深入研究有望丰富和拓展白狼国与藏彝走廊的研究内容。
