黄土高原260万年以来东亚夏季风演变信号研究

在研究黄土高原东亚季风地质时期周期演变中,引入了用于定量检测周期的奇异谱分析方法,结合小波分析,对典型的黄土高原陕西省洛川黄土剖面、甘肃省灵台黄土剖面的磁化率中2.6 MaB.P.以来东亚季风的强信号进行了研究。结果表明:2.6-1.0 MaB.P.之间地质时期,除在1.87-1.37 MaB.P.之间可能存在一个周期演变不明显的缺失时段外,东亚季风演变的主导周期是40 ka,0.9-0.6 MaB.P.是40 ka周期和100 ka周期的调整过渡期。0.6 MaB.P.以来的主导周期是100ka。研究还发现,1.2 MaB.P.前后没有明显的周期差异,说明1.2 MaB.P.不是一次真正意义上的周期转型事件,而是周期演变过程中的触发事件,这一触发事件对0.9 MaB.P.以后出现的周期转型事件影响深刻。40 ka周期从1.2 MaB.P.开始衰减,至0.9MaB.P.时100 ka周期逐渐建立。0.6 MaB.P.开始东亚季风出现冷暖大幅振荡的100 ka演变周期,因而0.6MaB.P.具有气候振荡加剧的突变性质。     

新建人工深水湖泊沉积物上覆水和孔隙水中溶解性有机质的光谱特征

为了揭示湖库内源性污染物的分布、来源、组成及垂向分布特征,以新建人工深水湖泊龙景湖为研究对象,采用紫外-可见光谱和三维荧光光谱技术,研究了该湖泊以成湖前用途划分的3个特征区域(原河道底部、新淹没区底部和新淹没区边坡)的沉积物上覆水和孔隙水中的溶解性有机质(DOM)的光谱特征.结果表明,孔隙水中的DOM芳香性和腐殖化程度高于上覆水;孔隙水中疏水组分含量大于上覆水,且水体中可能存在内源孔隙水释放的低分子量DOM.龙景湖上覆水和孔隙水中的DOM主要源于水体自身的微生物,自生源特征明显,且可能存在新近释放到水体的有机质.龙景湖沉积物上覆水和孔隙水中的DOM以类腐殖酸和类蛋白质为主,且随着深度增加,类腐殖酸峰强度增强,与龙景湖的建湖背景有明显联系.     

乌审旗近50a气候变化特征分析

文章通过对乌审旗1961—2010年气温及降水资料进行分析,揭示了近50a来乌审旗气候变化特征,结果表明:近50a,乌审旗年平均气温呈明显上升趋势,四季温度变化对年平均气温上升贡献:冬季春季秋季夏季;年降水量呈微弱下降态势。在全球气候变暖的背景下,乌审旗气温上升,降水量减少,气候有向暖干化发展的趋势。     

Indices of El Nino and El Nino Modoki： An Improved El Nino Modoki Index

In recent years, El Nino Modoki (pseudo-El Nino) has been distinguished as a unique large-scale ocean warming phenomenon happening in the central tropical Pacific that is quite different from the traditional El Nino. Empirical Orthogonal Function (EOF) analysis is used to successfully separate El Nino and El Nino Modoki. The abilities of the NINO3 index, NINO3.4 index, NINO1+2 index and NINO4 index in characterizing the El Nino are explored in detail. It is suggested that the NINO3 index is comparatively optimal to monitor the El Nino among the four NINO indices, since other NINO indices either cannot well distinguish El Nino and El Nino Modoki signals or are easily disturbed by El Nino Modoki signals. Further, an improved El Nino Modoki index (IEMI) is introduced to better represent the El Nino Modoki that is captured by the second leading EOF mode of monthly tropical Pacific sea surface temperature anomalies (SSTA). The IEMI is an improvement of the El Nino Modoki index (EMI) through adjusting the inappropriate weight coefficients of the three boxes of EMI, and it effectively overcomes the lack of EMI in monitoring the two historical El Nino Modoki events and also avoids the possible risk of EMI in excluding the interference of El Nino signal, indicating the realistic and potential advantages.     

Spatial and Temporal Distributions of Atmospheric CO2 in East China Based on Data from Three Satellites

East China (23.6°–38.4°N, 113.6°–122.9°E) is the largest developed region in China. Based on CO₂ products retrieved from the Greenhouse Gases Observing Satellite (GOSAT), the spatial and temporal distributions of CO₂ mixing ratios in East China during 2014–17 are discussed, and the retrieved CO₂ from AIRS (Atmospheric Infrared Sounder) and OCO-2 (Orbiting Carbon Observatory-2), as well as WLG (Waliguan) background station observations, are compared with those of GOSAT. The annual CO₂ retrieved from GOSAT in East China ranged from 398.96 ± 0.24 ppm in 2014 to 407.39 ± 0.20 ppm in 2017, with a growth rate of 2.82 ± 0.15 ppm yr^?1, which were higher than in other regions of China. The seasonal cycle presented a maximum in spring and a minimum in summer or autumn. Higher values were mainly concentrated in the coastal areas of Zhejiang Province, and lower values were concentrated in Jiangxi and the north of Fujian Province. CO₂ observed in Fujian and parts of Jiangxi increased by less than 1.0 ppm during 2014–15, but enhanced significantly by more than 5.0 ppm during 2015–16, perhaps influenced by local emissions and global impacts. We calculated year-to-year CO₂ enhancements in the Yangtze River Delta region during 2014–17 that were relatively low and stable, due to the region’s carbon emissions control and reduction policies. The annual and seasonal amplitudes of CO₂ retrieved from AIRS were lower than those from GOSAT in East China, probably owing to the CO₂ retrieved from AIRS better reflecting the characteristics of the mid-troposphere, while GOSAT is more representative of near-surface CO₂. The spatial and temporal distribution characteristics of CO₂ retrieved from OCO-2 were close to those from GOSAT in East China.     

南大别高压-超高压过渡类型榴辉岩的确定及其构造意义

通过对大别山太湖地区榴辉岩的岩石学、矿物成分和峰期变质P-T条件的研究表明,南大别榴辉岩可分为:①高压榴辉岩;②高压/超高压过渡榴辉岩;③超高压榴辉岩。它们的峰期变质P-T条件分别为:T=570℃～680℃,P=2.00 GPa～2.40 GPa;T=650℃～810℃,P=2.70 GPa～3.20 GPa;T=760℃～980℃,P=3.50 GPa～4.00 GPa,表明三类榴辉岩形成于不同的变质环境中。其中高压/超高压过渡榴辉岩是本次研究新近确定的,该类榴辉岩无论是在变质环境,还是在岩石结构、成分特征方面,均显示了高压-超高压过渡变质的特征。这种榴辉岩的存在解释了南大别变质块体俯冲时的连续性和折返后的断块特征。     

岩溶土壤系统对空气CO2的吸收及其对陆地碳汇的意义——以桂林丫吉村岩溶试

以桂林丫吉村岩溶实验场为例 ,对湿润亚热带岩溶土壤系统进行了土壤植被系统CO2 浓度变化、土壤有机质分解的CO2 产生等野外观测以及实验室土壤灰岩土柱系统模拟实验。实验表明在土壤地球化学条件的控制下 ,岩溶土壤系统存在着对空气CO2 的显著吸收效应 ,其值可达 2 2～ 130 g/ (m2 ·a) ,并以此为依据估算了中国岩溶土壤系统对大气的碳汇约为 4× 10 13g/a。因而揭示了岩溶土壤系统可能是十分重要的陆地碳汇 ,在讨论全球碳汇饱和问题中必须重视这一碳汇的变化。