利用树轮宽度重建黄河源区1618—2009年5—6月最高气温

利用采集自青海省雪山乡的祁连圆柏建立树轮宽度标准年表,将标准年表与黄河源区内4个气象站各气象要素作相关分析,结果显示整个源区5—6月最高气温与标准年表相关性最显著,相关系数为-0.65。根据相关分析结果,重建了黄河源区1618—2009年5—6月最高气温距平序列,重建方程经过逐一剔除检验,方差解释量达42.2%,具有一定的可靠性。重建序列在近400年间先后经历了8个较暖时间段和8个较冷时间段,暖期时段有1644—1656、1727—1746、1786—1797、1817—1835、1860—1885、1916—1934、1952—1968和1992—2005年,冷期的时段分别为1632—1643、1657—1696、1747—1764、1798—1816、1836—1859、1898—1915、1935—1951和1969—1991年。对比本次重建序列与杂多、青藏高原东部以及长江源的气温重建序列,发现以上序列在公共时段变化趋势一致,另外,一些文献和历史记载也证实了此次重建的可靠性。     

Speleothems as high-resolution paleoenvironment archives: Records from northeastern China

The isotopic compositions of oxygen and carbon and trace concentrations of magnesium and strontium in speleothems formed in limestone caves respond to climate changes outside the caves. Measurements of these properties on a stalagmite from Shihua Cave near Beijing, China, allowed reconstruction of the regional changes in precipitation, temperature and nature of vegetation. Over the last ∼ 500 years, there were fourteen precipitation cycles with a periodicity of 30–40 years, which may well reflect fluctuations in the strength of the East Asian summer monsoons reaching northeastern China. Relative to the mean temperature of this time interval, the period 1620–1900 AD was cold and periods 1520–1620 and 1900–1994 were warm. Over the last ∼ 3000-years, about eight wet/cool-dry/warm climatic cycles of 300–400 years duration occurred, the latest wet/cool half cycle corresponding to the Little Ice Age. The δ¹³C record registers the anthropogenic activities of fossil fuel CO₂ combustion in recent decades and regional deforestation between 13 and 16 centuries when Beijing was bustling with palatial constructions and being developed into the world’s most populated city.     

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差巴嘎蒿繁殖若干问题的探讨

差巴嘎蒿（Ａｒｔｅｍａｓｉａｈａｌｏｄｅｎｄｒｏｎ）营养繁殖的最佳材料是当年生带根基部营养枝；降水量是影响营养繁殖成活率的主导因子，栽植后５日内降水之和（ｘ）与成活率（ｙ）的相关系数为０．９７０１，回归方程为：ｙ＝３４．０２３６＋４１．０４６７１ｇｘ。营养繁殖应在有一定降水的条件下及时进行，最佳时间在６月中旬。不宜利用种子繁殖建立人工植被。     

Optical dating of sand wedges and ice‐wedge casts from Qinghai Lake area on the northeastern Qinghai‐Tibetan Plateau and its palaeoenvironmental implications

Sand wedges and ice‐wedge casts in the Qinghai Lake area on the northeastern Qinghai‐Tibetan Plateau (QTP) occur within alluvial gravel or river terrace deposits. In this study, we report the results of quartz Optically Stimulated Luminescence (OSL) dating of the infill of five relict sand wedges and one ice‐wedge cast. Combining our dating results with previously published luminescence ages of permafrost wedges in the Qinghai Lake area, we show that sand/ice wedges formed at c. 62 ka, c. 45 ka and between 30 and 15 ka, and that the mean annual air temperature (MAAT) was depressed by at least ～3°C relative to present during the sand/ice‐wedge formation periods. This new work is partially corroborated by post‐LGM proxy records from lakes and aeolian deposits reported from the northeastern QTP. It also significantly extends the palaeoenvironmental record in the region in the period before the LGM, when other proxy records are rare, allowing a better understanding of the palaeoenvironmental conditions on the northeastern QTP.     

Residual drift demands in moment‐resisting steel frames subjected to narrow‐band earthquake ground motions

This paper presents the main results of the evaluation of residual inter‐story drift demands in typical moment‐resisting steel buildings designed accordingly to the Mexican design practice when subjected to narrow‐band earthquake ground motions. Analytical 2D‐framed models representative of the study‐case buildings were subjected to a set of 30 narrow‐band earthquake ground motions recorded on stations placed in soft‐soil sites of Mexico City, where most significant structural damage was found in buildings as a consequence of the 1985 Michoacan earthquake, and scaled to reach several levels of intensity to perform incremental dynamic analyses. Thus, results were statistically processed to obtain hazard curves of peak (maximum) and residual drift demands for each frame model. It is shown that the study‐case frames might exhibit maximum residual inter‐story drift demands in excess of 0.5%, which is perceptible for building's occupants and could cause human discomfort, for a mean annual rate of exceedance associated to peak inter‐story drift demands of about 3%, which is the limiting drift to avoid collapse prescribed in the 2004 Mexico City Seismic Design Provisions. The influence of a member's post‐yield stiffness ratio and material overstrength in the evaluation of maximum residual inter‐story drift demands is also discussed. Finally, this study introduces response transformation factors, T_p, that allow establishing residual drift limits compatible with the same mean annual rate of exceedance of peak inter‐story drift limits for future seismic design/evaluation criteria that take into account both drift demands for assessing a building's seismic performance. Copyright © 2013 John Wiley & Sons, Ltd.     

Contribution to the Global Warming Mitigation of Marshlands Conversion to Croplands in the Sanjiang Plain,Northeast China

Based on the estimation of greenhouse gases (GHG) emissions and carbon sequestration of the total conversion of marshlands (TMC), marshlands conversion to paddy fields (MCPFs) and marshlands conversion to uplands (MCULs), this study revealed the contribution to the global warming mitigation (CGWM) of paddy fields versus uplands converted from marshlands in the Sanjiang Plain (excluding the Muling‐Xingkai Plain on south of Wanda Mountain), Heilongjiang Province, northeast China. The results showed that the total area of MCPFs and MCULs was 504.23 × 10³ ha between 1982 and 2005. The CGWM per unit area was 45.53 t CO₂eq/ha for MCPFs and that was 23.95 t CO₂eq/ha for MCULs, with an obvious 47.40% reduction. The MCPFs and MCULs ecosystems acted as the carbon sink all of the year. As far as CGWM per unit area is concerned, MCPFs mitigated the greenhouse effect which was greater than MCULs. And it was effective that the implementation of the uplands transformed into paddy fields in Northeast China with regard to marshlands protection and croplands (including paddy fields and uplands) reclamation.     

论海水养殖的养殖容量

养殖容量应是一个包含环境、生态和经济等诸多因素的综合概念。养殖容量可定义为：单位水体内在保护环境、节约资源和保证应有效益等各个方面都符合可持续发展要求的最大养殖量。合理地利用养殖容量就是要形成一个结构优化和功能高效的养殖生态系统,使所投入的物质得到反复循环、初级生产力得到多途径利用,从而提高生产效益和养殖效益,避免物质的浪费及自身和环境的污染。从养殖生态系统运转的驱动因素来分析,主要靠太阳辐射直接提供能源的系统,如海带养殖系统、扇贝筏式养殖系统等,可称为自养型或自然营养型养殖系统;主要靠人工投饲来提供能源的系统,如对虾池塘养殖系统、吃食性鱼类网箱养殖系统等,可称为异养型或人工营养型养殖系统。这两类养殖系统在生态学上有很多互补性,它们的复合可提高养殖水体的养殖容量。     

The mineral chemistry of pyroxenite xenoliths in the volcanic rocks of Hoh Xil and their significance

The pyroxenite xenoliths in the volcanic rocks of Hoh Xil consist of clinopyroxenes and orthopyroxenes. The mineral composition of these pyroxenes is similar to that of mantle xenoliths including peridotite and pyroxenite from China and abroad, and different from that of granulites. The pyroxenes formed at 1101–1400°C (averaging 1250°C) and under 30–60 kb (averaging 46 kb). We deduced that the magma was derived from the mantle at a depth of more than 150 km, which fits in with the geophysical conclusion that the low-velocity layer existed in the mantle under 150 km.