基于水质荧光指纹法的湖泊污染溯源研究——以太湖流域滆湖为例

随着社会经济和城市化进程的快速发展,湖泊水环境污染问题日益突出,加剧了湖泊原有功能的退化和丧失,因此污染治理成为了湖泊功能恢复和可持续发挥的必要条件,但如何实现污染精准溯源又是污染治理的重要前提。为此,本文以太湖流域滆湖为例,采用一种新兴技术——水质荧光指纹法开展湖泊污染溯源。于2021年累计采集滆湖周边70个农业、13个生活、3个企业排口的瞬时出水构建污染源荧光指纹库,连续12个月采集滆湖湖体8个样点水样分析水体荧光组分。通过平行因子分析共解析出4种污染源指纹和滆湖5种水体组分,经荧光相似度(塔克同余系数)分析进一步明确滆湖主要受到种植业面源、生活源和工业源的影响。此外,荧光强度与叶绿素a浓度和藻密度的强相关性表明藻类繁殖活动也会影响滆湖。从不同污染源对滆湖的时空影响特征来看,种植业面源主要在春、夏季影响西部、中部水域,生活源主要在夏、冬季影响西部、北部水域,工业源主要在特定月份(3 4月、10 12月)影响西部水域,藻类繁殖活动主要在夏季影响湖体。通过荧光组分与水质参数的时空相关性分析得到农业源和总磷、总氮,生活源和氨氮、有机物参数(BOD₅、COD_...     

Primary dolostone related to the Cretaceous lacustrine hydrothermal sedimentation in Qingxi sag, Jiuquan Basin on the northern Tibetan Plateau

Based on comprehensive studies in petrography, petrofabric analysis and geochemistry, this paper describes a unique and rare laminated micritic ferruginous primary dolostone crystallized and precipitated from the alkaline hot brine under the conditions of the Mesozoic faulted lake basin. The main rock-forming mineral of this dolostone is ferruginous dolomite with a micritic structure. This dolomite mostly exhibits laminae of 0.1–1 mm thick and is often discovered with other minerals, such as albite, analcite, barite and dickite, which have at least two types of interbedded laminae. Petrogeochemistry reveals that this dolostone contains a large number of typomorphic elements of hydrothermal sedimentation, including Sb, Ba, Sr, Mn, and V. In addition, the LREE is in relatively high concentrations and possesses the typical REE distribution pattern with negative Eu anomaly. Oxygen isotope values (δ¹⁸O_PDB) range from 5.89‰ to 14.15‰ with an average of 9.69‰. The ratio of ⁸⁷Sr/⁸⁶Sr is between 0.711648 and 0.719546, with an average of 0.714718. These data indicate that the depositional environment is a stable, blocked, anoxic low-lying hot brine pool in the bottom of deep lake controlled by basement faults. The hydrothermal fluid is the alkaline hot brine formed by the combination of the infiltration lake water and mantle-derived magmatic water, consisting of many ions, including Ca²⁺, Mg²⁺ and Fe²⁺. Under the driving flow power of magmatic heat, gravity and compaction, the hydrothermal fluid overcame the overburden pressure and hydrostatic pressure of the lake water body, and boiled to explosion, and then the explosion shattered the original laminated micritic ferruginous primary dolostone near the vent and then formed a new type of dolostone called shattered “hydroexplosion breccias”. In the low-lying, unperturbed hot brine pool, far from the vent, the laminated micritic ferruginous primary dolostone was quickly crystallized and chemicals precipitated from the hydrotherm. This study of special rocks contributes to research into the causes of the formation of lacustrine carbonate rocks and dolostone. In particular, it provides new examples and research insights for future studies of the lacustrine dolomite from the similar Mesozoic and Cenozoic basins in China.     

Late Quaternary clay minerals off Middle Vietnam in the western South China Sea: Implications for source analysis and East Asian monsoon evolution

High-resolution clay mineral records combined with oxygen isotopic stratigraphy over the past 450 ka during late Quaternary from Core MD05-2901 off Middle Vietnam in the western South China Sea are re-ported to reconstruct a history of East Asian monsoon evolution. Variations in Illite, chlorite, and kaolinite contents indicate a strong glacial-interglacial cyclicity, while changes in smectite content present a higher frequency cyclicity. The provenance analysis indicates a mixture of individual clay minerals from various sources surrounding the South China Sea. Smectite derived mainly from the Sunda shelf and its major source area of the Indonesian islands. Illite and chlorite originated mainly from the Mekong and Red rivers. Kaolinite was provided mainly by the Pearl River. Spectral analysis of the kaolin-ite/(illite chlorite) ratio displays a strong eccentricity period of 100 ka, implying the ice sheet-forced win-ter monsoon evolution; whereas higher frequency changes in the smectite content show an ice sheet-forced obliquity period of 41 ka, and precession periods of 23 and 19 ka and a semi-precession period of 13 ka as well, implying the tropical-forced summer monsoon evolution. The winter monsoon evolution is generally in coherence with the glacial-interglacial cyclicity, with intensified winter monsoon winds during glacials and weakened winter monsoon winds during interglacials; whereas the summer monsoon evolution provides an almost linear response to the summer insolation of low latitude in the Northern Hemisphere, with strengthened summer monsoon during higher insolation and weakened summer monsoon during lower insolation. The result suggests that the high-latitude ice sheet and low-latitude tropical factor could drive the late Quaternary evolution of East Asian winter and summer monsoons, respectively, implying their diplex and self-contained forcing mechanism.     

On the period of the periodic orbits of the restricted three body problem

We will show that the period T of a closed orbit of the planar circular restricted three body problem (viewed on rotating coordinates) depends on the region it encloses. Roughly speaking, we show that, \(2 T=k\pi +\int _\Omega g\) where k is an integer, \(\Omega \) is the region enclosed by the periodic orbit and \(g:{\mathbb {R}}^2\rightarrow {\mathbb {R}}\) is a function that only depends on the constant C known as the Jacobian constant; it does not depend on \(\Omega \). This theorem has a Keplerian flavor in the sense that it relates the period with the space “swept” by the orbit. As an application we prove that there is a neighborhood around \(L_4\) such that every periodic solution contained in this neighborhood must move clockwise. The same result holds true for \(L_5\).     

Phase Equilibria Constraints on Relations of Ore-bearing Intrusionswith Flood Basalts in the Panxi Region, Southwestern China

There are two types of temporally and spatially associated intrusions within the Emeishan large igneous province (LIP); namely, small uitramafic subvolcanic sills that host magmatic Cu-Ni-Platinum Group Element (PGE)-bearing sulfide deposits and large mafic layered intrusions that host giant Ti-V magnetite deposits in the Panxi region. However, except for their coeval ages, the genetic relations between the ore-bearing intrusions and extrusive rocks are poorly understood. Phase equilibria analysis (Q-PI-OI-Opx-Cpx system) has been carried out to elucidate whether ore-bearing Panzhihua, Xinjie and Limahe intrusions are co-magmatic with the picrites and flood basalts (including high-Ti, low-Ti and alkali basalts), respectively. In this system, the parental magma can be classified as silica-undersaturated olivine basalt and silica-saturated tholeiite. The equivalents of the parental magma of the Xinjie and Limahe peridotites and picrites and iow-Ti basalts are silica-undersaturated, whereas the Limahe gabbro-diorites and high-Ti basalts are silica-saturated. In contrast, the Panzhihua intrusion appears to be alkali character. Phase equilibria relations clearly show that the magmas that formed the Panzhihua intrusion and high-Ti basalts cannot be co-magmatic as there is no way to derive one liquid from another by fractional crystallization. On the other hand, the Panzhihua intrusion appears to be related to Permian alkali intrusions in the region, but does not appear to be related to the alkali basalts recognized in the Longzhoushan lava stratigraphy. Comparably, the Limabe intrusion appears to be a genetic relation to the picrites, whereas the Xinjie intrusion may be genetically related to be low-Ti basaits. Additionally, the gabbro-diorites and peridotites of the Limahe intrusion are not co-magmatic, and the former appears to be derived liquid from high-Ti basalts.     

Late Carboniferous porphyry copper mineralization at La Voluntad,Neuquén,Argentina: Constraints from Re–Os molybdenite dating

The La Voluntad porphyry Cu–Mo deposit in Neuquén, Argentina, is one of several poorly known porphyry-type deposits of Paleozoic to Early Jurassic age in the central and southern Andes. Mineralization at La Voluntad is related to a tonalite porphyry from the Chachil Plutonic Complex that intruded metasedimentary units of the Piedra Santa Complex. Five new Re–Os molybdenite ages from four samples representing three different vein types (i.e., quartz–molybdenite, quartz–sericite–molybdenite and quartz–sericite–molybdenite ± chalcopyrite–pyrite) are identical within error and were formed between ~312 to ~316 Ma. Rhenium and Os concentrations range between 34 to 183 ppm and 112 to 599 ppb, respectively. The new Re–Os ages indicate that the main mineralization event at La Voluntad, associated to sericitic alteration, was emplaced during a time span of 1.7 ± 3.2 Ma and that the deposit is Carboniferous in age, not Permian as previously thought. La Voluntad is the oldest porphyry copper deposit so far recognized in the Andes and indicates the presence of an active magmatic arc, with associated porphyry style mineralization, at the proto-Pacific margin of Gondwana during the Early Pennsylvanian.     

Well placement optimization subject to realistic field development constraints

This work considers the well placement problem in reservoir management and field development optimization. In particular, it emphasizes embedding realistic and practical constraints into a mathematical optimization formulation. Such constraints are a prerequisite for the wider use of mathematical optimization techniques in well placement problems, since constraints are a way to incorporate reservoir engineering knowledge into the problem formulation. There are important design limitations that are used by the field development team when treating the well placement problem, and these limitations need to be articulated and eventually formalized within the problem before conducting the search for optimal well placements. In addition, these design limitations may be explicit or implicit. In this work, various design limitations pertaining to well locations have been developed in close collaboration with a field operator on the Norwegian Continental Shelf. Moreover, this work focuses on developing constraint-handling capability to enforce these various considerations during optimization. In particular, the Particle Swarm Optimization (PSO) algorithm is applied to optimize for the well locations, and various practical well placement constraints are incorporated into the PSO algorithm using two different constraint-handling techniques: a decoder procedure and the penalty method. The decoder procedure maps the feasible search space onto a cube and has the advantage of not requiring parameter tuning. The penalty method converts the constrained optimization problem into an unconstrained one by introducing an additional term, which is called a penalty function, to the objective function. In contrast to the penalty method, only feasible solutions are evaluated in the decoder method. Through numerical simulations, a comparison between the penalty method and the decoder technique is performed for two cases. We show that the decoder technique can easily be implemented for the well placement problem, and furthermore, that it performs better than the penalty method in most of the cases.     

中国古代牧业社会骨制品的初步考察:以新疆巴里坤石人子沟遗址为例

考古遗址出土骨制品的研究对于揭示古代社会的动物资源获取和利用、手工业生产、社会组织结构等问题具有重要意义。国内骨制品研究目前多集中在农业区域,这些研究为探讨新石器时代至青铜时代的动物使用及其与社会发展、早期国家形成的关系等问题作出了重要贡献。然而,针对牧业社会骨制品的考察十分缺乏。新疆哈密地区巴里坤草原分布有大量古代牧业文化遗址,石人子沟遗址（43°31'12.8"~43°34'28.9"N,93°13'44.8"~93°16'49.1"E）是其中一处青铜时代晚期至铁器时代早期的大型聚落。本文从动物考古学视角研究该遗址2006年至2011年发掘出土的426件骨制品。结果显示,石人子沟遗址骨制品的原料主要为以羊（Ovis aries/Capra hircus）、马（Equus caballus）为主的家养动物和以鹿（Cervidae）为主的野生动物,其中羊的比例最高（69.7%）,鹿（13.8%）、马（2.3%）次之,这与中原地区青铜时代农业文化遗址的骨制品多以牛为原料的情况明显不同。羊在骨制品原料中占绝对多数且大量使用羊距骨制品的现象是对石人子沟遗址以牧业为主的生业经济方式的直接反映。石人子沟遗址不同类型骨制品的制作各具特点,但整体表现出"省时省力"的特点,即对使用部位细致打磨,对非使用部位仅做简单处理。与中原地区商周时期大型制骨作坊规范化、规模化、产业化的骨器生产不同,石人子沟遗址未见专门的制骨场所,骨制品生产的操作链条也并不完整。遗址的骨制品生产可能是以家庭为单元进行的,产品的专业化、精细化程度也相对较低。该研究填补了我国古代牧业文化遗址出土骨制品动物考古学专门研究的空白,为进一步探究我国古代不同区域、不同生业经济基础下的制骨手工业面貌提供了重要资料。

     

Broad search for unstable resonant orbits in the planar circular restricted three-body problem

Unstable resonant orbits in the circular restricted three-body problem have increasingly been used for trajectory design using optimization and invariant manifold techniques. In this study, several methods for computing these unstable resonant orbits are explored including grid searches, flyby maps, and continuation. Families of orbits are computed focusing on orbits with multiple loops near the secondary in the Jupiter–Europa system, and their characteristics are explored. Different parameters such as period and stability are examined for each set of resonant orbits, and the continuation of several specific orbits is explored in more detail.     

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。