在精确AMS^(14)C测年的基础上,对采自重庆中梁山岩溶洼地的剖面样品进行了孢粉分析,并结合详细的历史文献资料,获取了该地区近700年以来的植被变迁与石漠化演化记录。结果显示:(1)1274—1553 cal a AD研究区周围主要分布以松属、柏科/...在精确AMS^(14)C测年的基础上,对采自重庆中梁山岩溶洼地的剖面样品进行了孢粉分析,并结合详细的历史文献资料,获取了该地区近700年以来的植被变迁与石漠化演化记录。结果显示:(1)1274—1553 cal a AD研究区周围主要分布以松属、柏科/杉科占优势的亚热带常绿针叶林,伴人植物花粉少量出现,人类活动相对较弱。(2)1553—1780 cal a AD,针叶树松属、柏科/杉科花粉含量下降,伴人植物花粉增多,指示研究区人类活动开始加强。(3)1780—1840 cal a AD,松属花粉含量急剧下降,灌木和伴人植物花粉急剧增加,指示该地区人类活动加剧,石漠化现象出现。(4)1840—2000 cal a AD,玉米花粉含量大幅度增加,表明人类活动更加强烈,石漠化现象进一步加剧。近700年来不断增加的人类活动是重庆地区植被退化、石漠化现象严重的重要因素。该研究结果对重庆岩溶地区的全面治理,恢复和重建自然生态环境具有重要的指示意义。展开更多
Since the time of the rainy Holocene, there have been periods of consecutive rain and drought on Egypt. Study of carbon 14 in the long-lived coniferous tree rings could see activity in the sun （spots and solar flares...Since the time of the rainy Holocene, there have been periods of consecutive rain and drought on Egypt. Study of carbon 14 in the long-lived coniferous tree rings could see activity in the sun （spots and solar flares） during eleven years cycle, as well as knowledge of possible flooding of the Nile and the periods of increase and decrease of the extent necessary to meet the soil around Lake Qarun in Fayoum-Egypt. From historical records in ancient Egypt and Muslim countries, the possible link between periods of the disappearance of sunspots on the solar disc for several years and is known to inch lower level and role of the minimum level of Mandour creeping ice on Southern Europe to the Mediterranean Sea, and the offset of the drought in North Africa and the Sahel region of Africa during the last thousand years. Analyzed pollen fossils of the overlapped layers of soil in two areas of the Delta were Avaris in Sharkiya Province and Mendes in Dakahliya Province. The study pointed out that there are differences due to environmental conditions, demonstrated by the analysis of soil pH, increased electrical connectivity also, the evidence of sulfates and chlorides indicate high salinity of Mendes and Avaris. Also the analysis of fossil pollen of successive layers of soil for both regions resulted in findings of fossil pollen of the species Chenopodiaceae by 51.2%, in Mendes, while, 7% in the Avaris. This is strong evidence of the existence conditions of salt in Mendes than Avaris archaeological sites.展开更多
文摘在精确AMS^(14)C测年的基础上,对采自重庆中梁山岩溶洼地的剖面样品进行了孢粉分析,并结合详细的历史文献资料,获取了该地区近700年以来的植被变迁与石漠化演化记录。结果显示:(1)1274—1553 cal a AD研究区周围主要分布以松属、柏科/杉科占优势的亚热带常绿针叶林,伴人植物花粉少量出现,人类活动相对较弱。(2)1553—1780 cal a AD,针叶树松属、柏科/杉科花粉含量下降,伴人植物花粉增多,指示研究区人类活动开始加强。(3)1780—1840 cal a AD,松属花粉含量急剧下降,灌木和伴人植物花粉急剧增加,指示该地区人类活动加剧,石漠化现象出现。(4)1840—2000 cal a AD,玉米花粉含量大幅度增加,表明人类活动更加强烈,石漠化现象进一步加剧。近700年来不断增加的人类活动是重庆地区植被退化、石漠化现象严重的重要因素。该研究结果对重庆岩溶地区的全面治理,恢复和重建自然生态环境具有重要的指示意义。
文摘Since the time of the rainy Holocene, there have been periods of consecutive rain and drought on Egypt. Study of carbon 14 in the long-lived coniferous tree rings could see activity in the sun （spots and solar flares） during eleven years cycle, as well as knowledge of possible flooding of the Nile and the periods of increase and decrease of the extent necessary to meet the soil around Lake Qarun in Fayoum-Egypt. From historical records in ancient Egypt and Muslim countries, the possible link between periods of the disappearance of sunspots on the solar disc for several years and is known to inch lower level and role of the minimum level of Mandour creeping ice on Southern Europe to the Mediterranean Sea, and the offset of the drought in North Africa and the Sahel region of Africa during the last thousand years. Analyzed pollen fossils of the overlapped layers of soil in two areas of the Delta were Avaris in Sharkiya Province and Mendes in Dakahliya Province. The study pointed out that there are differences due to environmental conditions, demonstrated by the analysis of soil pH, increased electrical connectivity also, the evidence of sulfates and chlorides indicate high salinity of Mendes and Avaris. Also the analysis of fossil pollen of successive layers of soil for both regions resulted in findings of fossil pollen of the species Chenopodiaceae by 51.2%, in Mendes, while, 7% in the Avaris. This is strong evidence of the existence conditions of salt in Mendes than Avaris archaeological sites.
