鲁西新泰孟家屯2.7Ga变质沉积岩与黑云斜长片麻岩锆石Hf同位素特征

对出露于山东新泰孟家屯2.7Ga的孟家屯岩组中石榴石石英岩(M08)、含十字石石榴石黑云母石英片岩(D242-Y2)和黑云斜长片麻岩(M03)(TTG质片麻岩)进行锆石Lu-Hf同位素分析。石榴石石英岩锆石核部176Lu/177Hf、176Hf/177Hf变化范围为0.001730～0.002546、0.281249～0.281360,锆石变质边部176Lu/177Hf、176Hf/177Hf变化范围为0.000123～0.002070、0.281241～0.281318;含十字石石榴石黑云母石英片岩锆石核部176Lu/177Hf、176Hf/177Hf变化范围为0.001334～0.002169、0.281226～0.281324,锆石变质边部176Lu/177Hf、176Hf/177Hf变化范围为0.000445～0.001375、0.281227～0.281309;黑云斜长片麻岩锆石176Lu/177Hf、176Hf/177Hf变化范围为0.000315～0.000847、0.281186～0.281265。孟家屯岩组石榴石英岩、含十字石石榴石黑去母石英片岩中碎屑(岩浆)锆石和黑云斜长片麻岩中岩浆锆石的εHf(t)分别为3.75～7.26、2.31～7.26和3.21～6.27,同时TDM1与其U-Pb年龄非常接近,表明它们起源于新生地壳的部分熔融。结合区域研究资料认为,2.7Ga是鲁西重要的一期构造岩浆热事件,也可能是华北克拉通重要的构造岩浆活动时期。变质沉积岩中许多变质增生锆石相对于核部岩浆锆石低176Lu/177Hf、高176Hf/177Hf,显示变质作用过程中石榴石的存在对锆石的Lu-Hf同位素体系有很大影响。     

Concentrations and contamination trends of heavy metals in the sediment cores of Taihu Lake,East China,and their relationship with historical eutrophication

To assess the contamination trends and potential bio-availability of sediment-bound heavy metals, concentrations of heavy metals in acid-leaching fraction and in bulk sediments from the two typical bays (the Meiliang Bay and Xuhu Bay) of the Taihu Lake, East China, were studied. Pb and Zn showed elevated concentrations in the sediments from both areas, although sedimentation history and degree of pollution are different between the two bays. In the Meiliang Bay, both Pb and Zn pollutions started in the late 1970’s, the same time as the beginning of eutrophication of the lake, while the in the Xuhu Bay the metal contamination started since recent 10 years. The concentrations of acid-leachable Pb in the sediments from the Meiliang Bay are correlated with the historical eutrophication process. Before the eutrophication and heavy metal pollution, the chemical properties of the lake sediments were the same as the source compositions of the Xiashu loess. Both Pb and Zn in the sediments mainly occur in leachable forms by nitric or hydrochloric acid, whilst most of Cu is in residual fraction. The results indicate that both Pb and Zn may have higher mobility and bioavailability in water and biology than Cu.     

新疆哈密图拉尔根Ni-Cu硫化物矿床成矿模式研究

新疆图拉尔根Ni-Cu硫化物矿床产于康古儿塔格—黄山韧性剪切带的北东段,属于岩浆熔离贯入型矿床。1号岩体以全岩矿化为特征,各岩相环带状产出,岩性具有单期岩浆多次脉动上涌成矿特征。由大地电磁测深剖面图、稀土元素配分曲线和微量元素可知1号和2号岩体具有同源性,并具有互补性,在深部具有同一个岩浆通道。较低的La/Sm(2)和Th/Ta值(4.6)表明成矿岩浆为地幔来源,岩体就位时很少受到地壳的混染。PGE特征表明,图拉尔根岩浆源于地幔低程度的部分熔融。Pd-Ni图显示在岩浆演化早期没有发生过硫化物的熔离作用。根据岩石学、岩相学、地球化学等资料综合分析,对图拉尔根Ni-Cu硫化物矿床的成矿模式进行了探讨,认为其成矿模式为深部熔离反相复式贯入成矿。构造在图拉尔根矿床就位过程中起了重要影响,决定了矿体的产出状态。     

我国海水贝类养殖低碳效应评价

食物生产系统的碳排放占人类活动碳排放总量的 30%, 碳汇渔业是一种重要的面向人类社会高质量食物蛋白质供给 的低碳发展路径。本文基于常见的 11 种养殖贝类的固碳系数和蛋白质含量特性研究,系统评估了我国2019 年养殖牡蛎 、蛤 类、扇贝、贻贝和蚶类等在养殖周期内碳捕集特性以及对低碳发展的贡献。研究表明： (1) 11 种养殖贝类之间贝壳和软体 组织含碳量的差异并不明显,但干重比和出肉率差异显著。因此,贝类固碳量核算不能忽视种类差异。 (2)所选 11 种贝类 软体组织皆属于高蛋白食品,虾夷扇贝软体组织 (干重) 的蛋白质含量最高。针对单位质量贝类养殖,长牡蛎的碳封存贡献 度最大,而华贵栉孔扇贝提供的蛋白质最多,两者都是碳汇渔业的优势种。(3) 据估算,我国2019 年海水养殖贝类中牡蛎、蛤 类 、扇贝和蚶类总共吸收固定了约 117.98 万吨 C02,提供了 40.65 万吨蛋白质 。这些蛋白质相比于牛肉源蛋白质可减少 4 048.74 万吨 C02 当量的排放量。由于贝类固碳强度大,探索低碳可持续的贝类养殖是绿色渔业经济的重要引擎, 也是建立可持续高质量“蓝色粮仓”和生物固碳的重要路径, 将在我国低碳产业发展中发挥重要作用。     

莒县农村集体土地确权登记发证探析

农村产权制度改革试点工作启动以来,莒县农村集体土地确权办及时进行实地调研,全面了解分析村情,确定工作方案,调整工作重点。但工作中存在权属争议较多、历史遗留问题多、时间紧迫、所需经费较多等问题,今后工作中应加大力度,创新工作方法,妥善调处好各类土地权属纠纷;加大软件开发力度,全面实现土地登记信息化;充分应用调查成果,积极服务社会经济发展,以确保农村集体土地确权登记发证工作按时、全部完成。     

遗忘因子自适应最小二乘算法及其在气温预报中的应用

海量数据的利用是建立自适应预报模型的基础,但随着数据的不断增加,新引入数据的作用会逐渐降低,有可能导致预报模型失效。为克服因数据量增加引起的所谓"数据饱和"现象对天气预报效果的影响,本文给出了考虑遗忘因子的线性自适应最小二乘建模算法的原理和方法,并利用该算法进行了最高气温和最低气温预报试验。结果表明,考虑遗忘因子的线性自适应建模算法优于传统的线性自适应建模算法,加入遗忘因子可以避免产生"数据饱和"现象,适当地选择遗忘因子有助于提高模型的预报准确率。     

探空观测黑名单检查在变分同化系统中的应用

针对探空观测资料使用造成的某些区域GRAPES分析场存在虚假的高、低压系统问题,该文通过对比全球探空资料的位势高度观测与NCEP分析场,统计站点中观测质量较差的时次出现频数,确定探空位势高度观测黑名单。研究表明:500 hPa在印度地区、北大西洋和南极洲附近的探空位势高度观测与NCEP分析场的均方根误差在30 gpm以上的站点较多,且位势高度观测不可靠观测比率为20%以上的站点主要集中这些区域,以上观测站均列入黑名单。文中在GRAPES全球三维变分分析场的质量控制中加入探空位势高度观测黑名单检查,通过6 h分析预报循环试验表明:探空位势高度观测黑名单检查能有效提高分析场质量,GRAPES位势高度分析场在南极洲附近和印度地区有所改善。     

Signal acquisition of Luojia-1A low earth orbit navigation augmentation system with software defined receiver

Low Earth Orbit (LEO) satellite navigation signal can be used as an opportunity signal in the case of a Global Navigation Satellite System (GNSS) outage, or as ...     

Response of evapotranspiration and water availability to the changing climate in Northern Eurasia

We introduce a probabilistic framework for vulnerability analysis and use it to quantify current and future vulnerability of the US water supply system. We also determine the contributions of hydro-climatic and socio-economic drivers to the changes in projected vulnerability. For all scenarios and global climate models examined, the US Southwest including California and the southern Great Plains was consistently found to be the most vulnerable. For most of the US, the largest contributions to changes in vulnerability come from changes in supply. However, for some areas of the West changes in vulnerability are caused mainly by changes in demand. These changes in supply and demand result mainly from changes in evapotranspiration rather than from changes in precipitation. Importantly, changes in vulnerability from projected changes in the standard deviations of precipitation and evapotranspiration are of about the same magnitude or larger than those from changes in the corresponding means over most of the US, except in large areas of the Great Plains, in central California and southern and central Texas.