中国典型季风海洋性冰川区雪坑环境记录分析

白水1号冰川是亚欧大陆纬度位置最低的冰川,冰川区90%的降水主要受季风气候影响。运用多种方法对该区雪坑化学的季节性特征分析表明,2006年5月7日采集的两雪坑主要是2005年夏季风期和2005~2006年度非夏季风期的积雪积累;夏季风期积雪中远源物质主要是随季风环流而来的海盐气溶胶及其沿途工、农业区的污染物质,非夏季风期主要是源自印度塔尔沙漠以及中亚和西亚地区的粉尘;季风期和非季风期(2005~2006年度)间积雪化学特征存在较大差异;两雪坑季风期间积雪化学特征的不同主要反映了不同海拔消融强度和淋溶过程的差异,非季风期间的不同主要反映了局地环境的影响,特别是山谷风携带的地壳物质的影响。     

Production and recycling of oceanic crust in the early Earth

Because of the strongly different conditions in the mantle of the early Earth regarding temperature and viscosity, present-day geodynamics cannot simply be extrapolated back to the early history of the Earth. We use numerical thermochemical convection models including partial melting and a simple mechanism for melt segregation and oceanic crust production to investigate an alternative suite of dynamics which may have been in operation in the early Earth. Our modelling results show three processes that may have played an important role in the production and recycling of oceanic crust: (1) Small-scale (x×100 km) convection involving the lower crust and shallow upper mantle. Partial melting and thus crustal production takes place in the upwelling limb and delamination of the eclogitic lower crust in the downwelling limb. (2) Large-scale resurfacing events in which (nearly) the complete crust sinks into the (eventually lower) mantle, thereby forming a stable reservoir enriched in incompatible elements in the deep mantle. New crust is simultaneously formed at the surface from segregating melt. (3) Intrusion of lower mantle diapirs with a high excess temperature (about 250 K) into the upper mantle, causing massive melting and crustal growth. This allows for plumes in the Archean upper mantle with a much higher excess temperature than previously expected from theoretical considerations.     

Impact of Non-Methane Hydrocarbons on Tropospheric Chemistry and the Oxidizing Power of the Global Troposphere: 3-Dimensional Modelling Results

The impact of natural and anthropogenicnon-methane hydrocarbons (NMHC) on troposphericchemistry is investigated with the global,three-dimensional chemistry-transport model MOGUNTIA.This meteorologically simplified model allows theinclusion of a rather detailed scheme to describeNMHC oxidation chemistry. Comparing model resultscalculated with and without NMHC oxidation chemistryindicates that NMHC oxidation adds 40–60% to surfacecarbon monoxide (CO) levels over the continents andslightly less over the oceans. Free tropospheric COlevels increase by 30–60%. The overall yield of COfrom the NMHC mixture considered is calculated to beabout 0.4 CO per C atom. Organic nitrate formationduring NMHC oxidation, and their transport anddecomposition affect the global distribution of NO _x and thereby O₃ production. The impact of theshort-lived NMHC extends over the entire tropospheredue to the formation of longer-lived intermediateslike CO, and various carbonyl and carboxyl compounds.NMHC oxidation almost doubles the net photochemicalproduction of O₃ in the troposphere and leads to20–80% higher O₃ concentration inNO _x -rich boundarylayers, with highest increases over and downwind ofthe industrial and biomass burning regions. Anincrease by 20–30% is calculated for the remotemarine atmosphere. At higher altitudes, smaller, butstill significant increases, in O₃ concentrationsbetween 10 and 60% are calculated, maximizing in thetropics. NO from lightning also enhances the netchemical production of O₃ by about 30%, leading to asimilar increase in the global mean OH radicalconcentration. NMHC oxidation decreases the OH radicalconcentrations in the continental boundary layer withlarge NMHC emissions by up to 20–60%. In the marineboundary layer (MBL) OH levels can increase in someregions by 10–20% depending on season and NO _x levels.However, in most of the MBL OH will decrease by10–20% due to the increase in CO levels by NMHCoxidation chemistry. The large decreases especiallyover the continents strongly reduce the markedcontrasts in OHconcentrations between land and oceanwhich are calculated when only the backgroundchemistry is considered. In the middle troposphere, OHconcentrations are reduced by about 15%, although dueto the growth in CO. The overall effect of thesechanges on the tropospheric lifetime of CH₄ is a 15%increase from 6.5 to 7.4 years. Biogenic hydrocarbonsdominate the impact of NMHC on global troposphericchemistry. Convection of hydrocarbon oxidationproducts: hydrogen peroxides and carbonyl compounds,especially acetone, is the main source of HO _x in theupper troposphere. Convective transport and additionof NO from lightning are important for the O₃ budgetin the free troposphere.     

福建东山湾八尺门海域水体及沉积物中的重金属污染评价

本研究分析了2013年10月东山湾八尺门海域表层海水和沉积物中重金属Zn、Cu、Pb、Cd含量,并基于多种方法进行评价。结果显示,研究海域表层海水中重金属含量符合《海水水质标准》第一类标准,重金属污染指数法评价显示污染风险较低。沉积物中Pb、Cd、Zn含量均符合《海洋沉积物质量》第一类标准,整体污染水平较低;潜在生态风险指数大小顺序为：Cd>Cu>Pb>Zn,沉积物重金属污染整体情况良好,但个别站位的Cd的潜在生态风险指数超过40,应加以关注;地累积指数评价法显示总体污染情况较轻,其地累积指数平均值大小依次为Zn>Cu>Pb>Cd。纵观1990年至2013年的研究结果,东山湾水体中重金属含量总体呈先升高后降低的趋势;与同期相比,东山湾水体中的重金属含量与福建其他海域相差不大,而沉积物中重金属含量比其他海域稍高。     

岩溶水系统对大气CO2的潜在影响——基于热力学的研究

认识不同条件下岩溶水释放或吸收CO2的反应过程是研究碳酸盐岩对碳循环响应的前提和基础。本文从吉布斯自由能的热力学原理出发,对全球不同岩溶地区162组岩溶水(河水、溪水、湖水等)进行了热力学研究,结果显示:1)河水、溪水、湖水和洞穴滴水等岩溶水所处的环境因方解石矿物沉积而释放CO2成为大气CO2一个潜在的源;2)地下水在所处的环境下由于方解石的溶解而吸收CO2,成为大气CO2一个潜在的汇;3)少数出露点的泉水所处的环境既可发生方解石的溶解而吸收CO2,成为大气CO2的潜在汇,也可发生方解石的沉积而释放CO2,成为大气CO2的潜在源;4)在洪水期,泉水的水化学特征变化并未导致对大气CO2潜在贡献在源汇之间的跨跃性转变。162组岩溶水数据中,所有河水与溪水皆无一例外地在释放CO2。结果表明,从吉布斯自由能的热力学原理出发,研究岩溶水系统对大气CO2潜在源汇的贡献,没有条件约束,是一种较好的途径。     

Identification of the source caldera for the Middle Miocene ash-flow tuffs in the Kii Peninsula based on apatite trace-element composition

A large caldera cluster consisting of at least four calderas (Omine, Odai, Kumano-North and Kumano calderas) existed in the central–southern part of the Kii Peninsula approximately 14–15 Ma. On the other hand, thick Middle Miocene ash-flow tuffs, referred to as the Muro Ash-flow Tuff and the Sekibutsu Tuff Member, are distributed in the northern part of the Kii Peninsula. Although these tuffs are considered to have erupted from the caldera cluster in the central-southern Kii Peninsula, identifying the source caldera in the cluster has been controversial because of similarities in the petrological characteristics and identical radiometric ages of the volcaniclastic rocks of these calderas. We successfully discriminated the characteristics of the eruptive products of each caldera in the caldera cluster based on the apatite trace-element compositions of the pyroclastic dikes and ash-flow tuffs of the calderas. We also demonstrated that the source caldera of at least the lower main part of the Muro Ash-flow Tuff and the Sekibutsu Tuff Member was the Odai Caldera, which is located in the central Kii Peninsula. Our findings show possible correlations among the pyroclastic conduits and ash-flow tuffs of the caldera-fill and/or outflow deposits, even in cases where they have been densely welded and diagenetically altered. This method is useful for the study of deeply eroded ancient calderas.     

江西大湖塘北段石门寺钨铜钼矿化关系研究

江南造山带中段的赣北大湖塘矿集区是我国近年查明的世界级超大型钨矿产地,并伴生大型铜矿。本文对该区北段石门寺矿区燕山期不同岩石单元的W、Cu、Mo矿化特征与成矿年龄进行了系统研究。白钨矿多呈细脉浸染状产于似斑状花岗岩及其与围岩的外接触带;黄铜矿与辉钼矿多呈浸染状共生于似斑状黑云母花岗岩、细粒黑云母花岗岩、黑云母花岗斑岩及其围岩中。矿石矿物化学研究表明,似斑状黑云母花岗岩、细粒黑云母花岗岩和黑云母花岗斑岩中的硫化物成分较均一,黄铜矿中Cu 34.215%~35.161%、Fe 29.206%~30.721%、S 34.388%~35.520%,辉钼矿中Mo 59.44%~60.54%、S 40.067%~40.370%;似斑状黑云母花岗岩、细粒黑云母花岗岩、黑云母花岗斑岩和石英大脉中的辉钼矿Re-Os同位素模式年龄均值分别为143.3 Ma、145.2 Ma、144.5 Ma、143.6Ma,在误差范围内基本相同,指示该矿区内的Cu、Mo矿化为一期成矿作用形成,由此给出辉钼矿Re-Os同位素等时线年龄145.1±1.0 Ma(MSWD=0.46),代表Cu、Mo矿化时间。结合前人岩浆岩研究结果,石门寺矿区白钨矿与Cu、Mo矿化是两期成矿作用的产物,前者与似斑状黑云母花岗岩密切相关,而后者可能与燕山晚期黑云母花岗斑岩有成因联系,成矿物质由斑岩向其他岩石单元迁移逐渐成矿。     

氟碳铈钡矿Ba3Ce2(CO3)5F2晶体结构重测

氟碳铈钡矿Ba₃Ce₂(CO₃)₅F₂的晶体结构原先被描述为Cm和P2空间群,经单晶X射线衍射方法重测为C2/m空间群;采用2339个独立反射,151个可变参数,R=0.034,R_w=0.05.经检测,未发现明显违反C心布拉维格子的反射;误差允许范围内位移椭球体与所定空间群相容。结构中的原子排列与化合物Ba₃La₂(CO₃)₅F₂相似,可被描述为平行于(102)层间有序结构,层与层之间通过碳酸根相联结。     

苍南沿浦湾浅海养殖区水质质量评价

根据2013~2015年对沿浦湾浅海养殖区的水质进行的监测与分析资料,采用富营养化指数法和有机污染指数法对该海域海水营养状况和有机污染状况进行了评价.结果表明,该养殖区海水的溶解氧(DO)和化学需氧量(COD)含量符合国家二类海水水质标准,超过二类标准的指标为无机氮(DIN)、活性磷酸盐(PO_4~(3-)-P)和石油类.该养殖区春、冬两季水质指标超标情况较为明显,春季超标指标为无机氮和石油类,冬季超标指标为无机氮和活性磷酸盐.该养殖区的富营养化程度日趋严重,而有机污染程度总体不高.     

A spatio-chemical survey of hydrogeothermal springs in Lake Elementaita, Kenya

The hydrochemistry of three areas of geothermal activity in the Lake Elementaita basin were surveyed. The results indicated warm temperatures between 30–40°C, high alkalinity (1,200 mg CaCO₃/l) and specific conductance (4,300–8,100 μS/cm). pH was above 9 with a high concentration of carbonates, chlorides and sulphates. Apart from playing a significant role in the lake chemistry, lacustrine springs provide a significant source of water supply, particularly during the dry season. However, there is a serious lack of scientific information on the hydrogeology and hydrochemistry of the thermal springs.