CLIMATIC RECORDS FROM ANNUAL LAYERS AND STABLE ISOTOPES OF A STALAGMITE IN BEIJING OVER THE LAST 2300 YEARS

Ｉ.ＩｎｔｒｏｄｕｃｔｉｏｎＳｔａｌａｇｍｉｔｅｓｈａｖｅｂｅｅｎａｐｐｌｉｅｄｔｏｕｓｅａｓｈｉｇｈｒｅｓｏｌｕｔｉｏｎｐａｌｅｏｃｌｉｍａｔｉｃｉｎｄｉｃａｔｏｒｓｓｉｎｃｅｔｈｅａｎｎｕａｌｇｒｏｗｔｈｂａｎｄｉｎｇｗａｓｒｅｃｏｇｎｉｚｅｄｉｎｓｔａｌａｇｍｉｔｅｓ[1,2].Ａｎｎｕａｌｇｒｏｗｔｈｂａｎｄｉｎｇｃａｎｂｅｍａｎｉｆｅｓｔｅｄｉｎｓｅｖｅｒａｌｍａｎｎｅｒｓｄｅｆｉｎｅｄｂｙ1)ａｌｔｅｒｎａｔｉｎｇｆｌｕｏｒｅｓｃｅｎｔａｎｄｎｏｎ-ｆｌｕｏｒｅｓｃｅｎｔｃａｌｃｉｔｅ[3,4];2)…     

Water-quality trends in White Rock Creek Basin from 1912-1994 identified using sediment cores from White Rock Lake reservoir, Dallas, Texas

Historical trends in selected water-quality variables from 1912 to 1994 in White Rock Creek Basin were identified by dated sediment cores from White Rock Lake. White Rock Lake is a 4.4-km² reservoir filled in 1912 and located on the north side of Dallas, Texas, with a drainage area of 259 km². Agriculture dominated land use in White Rock Creek Basin before about 1950. By 1990, 72% of the basin was urban. Sediment cores were dated using cesium-137 and core lithology. Major element concentrations changed, and sedimentation rates and percentage of clay-sized particles in sediments decreased beginning in about 1952 in response to the change in land use. Lead concentrations, normalized with respect to aluminum, were six times larger in sediment deposited in about 1978 than in pre-1952 sediment. Following the introduction of unleaded gasoline in the 1970s, normalized lead concentrations in sediment declined and stabilized at about two and one-half times the pre-1952 level. Normalized zinc and arsenic concentrations increased 66 and 76%, respectively, from before 1952 to 1994. No organochlorine compounds were detected in sediments deposited prior to about 1940. Concentrations of polychlorinated biphenyls (PCB) and DDE (a metabolite of DDT) increased rapidly beginning in the 1940s and peaked in the 1960s at 21 and 20 µg kg^-1, respectively, which is coincident with their peak use in the United States. Concentrations of both declined about an order of magnitude from the 1960s to the 1990s to 3.0 and 2.0 µg kg^-1, respectively. Chlordane and dieldrin concentrations increased during the 1970s and 1980s. The largest chlordane concentration was 8.0 µg kg^-1 and occurred in a sediment sample deposited in about 1990. The largest dieldrin concentration was 0.7 µg kg^-1 and occurred in the most recent sample deposited in the early 1990s. Agricultural use of chlordane and dieldrin was restricted in the 1970s; however, both were used as termiticides, and urban use of chlordane continued at least until 1990. Recent use of dieldrin and aldrin, which degrades to dieldrin, has not been reported; however, increasing trends in dieldrin since the 1970s suggest recent urban use could have occurred.     

柴达木盆地西部新生代气候与地形演变

从孢粉植物分异及演变，干旱碎屑及膏盐沉积分布等方面，对柴达木盆地西部新生代气候与地形的演变进行了探讨。结果表明，盆地西部新生代两个极端干燥气候期（膏盐发育期）分别出现在始新世至渐新世及上新世至第四纪。前者与老第三纪行星环流控制下的副热带干燥带有关，而后者与青藏高原的隆升有关。早第三纪盆地西部及周围地区的地势不象以前所认为的那么低平。在第三纪，昆仑山比祁连山低。晚新生代盆地向北推移了７－１１个纬距。     

欧洲中部地区晚更新世及全新世的泉华沉积

在中欧地区的河谷、洪积扇、山坡坡麓及湖底常零星分布着更新世及全新世的碳酸盐沉积物。不少学者把碳酸盐沉积当作气候变化的产物并划分出其在中欧沉积的若干时期。笔者通过德国中部Leine河流域新老石灰泉华的详细研究对泉华沉积与气候直接联系的观点提出了新的见解。运用不同方法测年验证，得知研究区的石灰泉华沉积始于11000aB.P,随后石灰泉华在研究区不同地点连续沉积。岩芯上沉积的变化和石灰泉华层的消失应是由地貌过程所引起的泉水出露位置改变所致。     

北极巴罗Elson湖过去450年气候与环境变化记录

北极阿拉斯加巴罗地区Ｅｌｓｏｎ湖长６０ｃｍＡＢ—６７钻孔岩芯提供了过去４５０年连续的高分辨环境变化记录。综合分析２１０Ｐｂ测年、沉积物粒度、有机质、化学元素和微体古生物化石等资料，一致反映出巴罗地区过去４５０年的气候、环境变化过程存在如下３个阶段：１）大约１５４０～１７４０年，为低海面寒冷时期；２）１７４０～１８２７年，为气候转暖－海侵过渡时期；３）１８２７年至今，为继续海侵－气候波动变暖时期。其中１８００年前后和１９４０年前后，气温较高。１９２１～１９９３年巴罗的气温记录说明，北极地区气温不仅有明显的１０ａ和６０ａ周期变化，而且年平均温度变幅极大，达４．５℃。显示极地气候变化特别强烈并不反映大幅度升温。近２０年来的变暖趋势是１８２７年以来自然的气候波动变暖的继续。     

塔里木及邻区晚古生代早期古气候与构造

影响塔里木及邻区晚古生代早期气候的地球内部因素为古昆仑和南天山两个古洋盆封闭及有关的两条缝合构造带演化，从而形成上述时空段内热带海洋气候、热（亚热）带季风气候、热带沙漠气候以及热带滨岸干湿气候区域的更替，古气候特征的判断主要依据古地磁数据、古生态气候学、沉积环境诸方面。     

陕西关中晚更新世黄土—古土壤序列特征及其记录的古环境变迁

陕西关中盆地的泾阳南塬和西安东郊席王晚更新世黄土剖面底部的Ｓ１古生境是由４层古土壤及与其相间的两层古土壤构成。这是目前发现的黄土高原晚更新世黄土，古土壤序列保存较好的剖面。两剖面的地层结构，磁化率曲线和地球化学组分反映出了１２个温湿，冷干气候变化阶段可以归纳为６个气候变化旋回。     

哺乳动物群指示的气候旋回——以周口店早更新世哺乳动物群为例

文章根据对周口店地区四个哺乳动物群的分析，讨论了该区早更新世气候及生态环境的变迁。第１８地点显示了约１．９０ＭａＢ．Ｐ．的干凉气候和森林—草原植被。第１２地点指示了１．７０ＭａＢ．Ｐ．的湿热气候和茂密森林生态环境。东洞则记录了１．２０ＭａＢ．Ｐ．的干冷气候和草原景观。到第９地点时（约１．００～０．９０ＭａＢ．Ｐ．），气候炎热，森林和草原植被同时发育     

Vicissitude of Sogo Nur and environmental-climatic change during last 1500 years

Lakes in arid zone are sensitive to climatic changes. The lacustrine sediment sequence in Sogo Nur has well and truly recorded climatic events such as the Sui-Tang Dynasty Warm Period, the Song-Liao Dynasty Cold Period, the Medieval Warm Period, the Little Ice Age and the 20th Century Warm Period. Commonly, the climate in warm Periods was relatively humid,accordingly the lake area extended and water level rose, and vice versa. Apart from climatic change, human activity is also an important factor of influencing lake vicissitude, and they played the dominant role alternatively during different periods; the factor of climatic change predominated in historical period, while since the beginning of the 20th century the utilization of water resources by human has became decisive.     

全球气候变化背景下的西北地区生态环境建设、可持续发展

本文通过对西北地区气候与生态环境、可持续发展的调查研究，提出我国应高度重视全球气候变化的影响，要在气候变化的背景下，通过人类的有序活动促进我国生态环境建设和经济社会的可持续发展，实现人和自然的和谐共存。