Middle Holocene Organic Carbon and Biomarker Records from the South Yellow Sea: Relationship to the East Asian Monsoon

The East Asian monsoon system influences the sedimentation and transport of organic matter in East Asian marginal seas that is derived from both terrestrial and marine sources. In this study, we determined organic carbon (OC) isotope values, concentrations of marine biomarkers, and levels of OC and total nitrogen (TN) in core YSC-1 from the central South Yellow Sea (SYS). Our objectives were to trace the sources of OC and variations in palaeoproductivity since the middle Holocene, and their relationships with the East Asian monsoon system. The relative contributions of terrestrial versus marine organic matter in core sediments were estimated using a two-end-member mixing model of OC isotopes. Results show that marine organic matter has been the main sediment constituent since the middle Holocene. The variation of terrestrial organic carbon concentration (OCter) is similar to the EASM history. However, the variation of marine organic carbon concentration (OCmar) is opposite to that of the EASM curve, suggesting OCmar is distinctly influenced by terrestrial material input. Inputs of terrestrial nutrients into the SYS occur in the form of fluvial and aeolian dust, while concentrations of nutrients in surface water are derived mainly from bottom water via the Yellow Sea circulation system, which is controlled by the East Asian winter monsoon (EAWM). Variations in palaeoproductivity represented by marine organic matter and biomarker records are, in general, consistent with the recent EAWM intensity studies, thus, compared with EASM, EAWM may play the main role to control the marine productivity variations in the SYS.     

三沙永乐龙洞洞底沉积速率变化及其影响因素

三沙永乐龙洞位于西沙永乐环礁,是目前世界范围内已探明的最深蓝洞,其内部沉积动力环境相对单一,是研究沉积速率变化的天然实验室。龙洞洞底约24 cm以浅沉积物粒度分析结果显示,洞底浅埋沉积物以砂质组分为主,平均粒径多介于22.9~123.9 μm之间,在表层、4 cm、9.5 cm以及21 cm深度分别出现了沉积物变粗、砂含量增多的现象;利用210Pb的CRS定年模式计算得到底层沉积物沉积时间为1896年,平均沉积速率为0.19 cm/a,在4 cm和9.5 cm深度沉积速率急剧增加。柱状样顶部沉积速率显著增加,与近年来西沙地区人类活动加剧吻合。沉积物粒度变粗以及沉积速率骤然加快现象,与西沙地区台风活动频繁相关,通过对比历史台风记录,验证了沉积物在1999-2001年以及2010-2011年所记录的6次台风事件:199902、199915、200110、201002、201005以及201118。推测龙洞洞底沉积物沉积速率主要受台风活动影响,近期有人类活动影响的痕迹。     

Benefit Sharing on Transboundary Rivers: Case Study and Theoretical Exploration

Benefit sharing on transboundary rivers is an approach to address equitable and reasonable development and utilization of transboundary water resources (TWR). Through analyzing a few typical benefit sharing cases, this paper provides a systematic discussion of the theory of TWR benefits sharing. TWR features a kind of common pool resources (CPRs). Its benefit sharing subjects are the riparian countries. The shared benefits usually include flood prevention, power generation, navigation, irrigation, contributions to society and culture, etc. The benefit sharing modes mainly include shared benefits and responsibilities, reciprocal rights and obligations, equal benefit distribution, cost proportion-based benefit sharing, and demand-based benefit sharing. The first step in the realization process of benefit sharing is the sharing of data and information. Second is the benefit identification and evaluation. Third is the establishment of a mechanism to guarantee the benefit sharing. The conditions for realizing benefit sharing depends on, first, if the riparian countries are willing to cooperate with each other; second, whether the cooperation can bring incremental benefit or cost reduction in comparison with unilateral operation; and third, if the benefit distribution is equitable and reasonable and can stand the test of time.     

舰船辐射噪声仿真模型置信度评估方法

根据舰船辐射噪声频域特性,从舰船辐射噪声线谱、谱密度的发展变化趋势、特征频段信号能量 3 个方面考虑,对舰船辐射噪声仿真数据和实测数据进行一致性分析,综合评估舰船辐射噪声仿真模型置信度。通过对舰船辐射噪声仿真模型置信度分析,为舰船辐射噪声仿真信号源置信度提供理论支撑。     

Linear Analysis of Longshore Currents Instability over Mild Slopes

Longshore current instability is important to nearshore hydrodynamic and sediment transport. This paper investigates the longshore current instability growth model based experimental data with different velocity profiles of slopes 1:100 and 1:40 by adopting a linear shear instability model with the bottom friction effects. The results show that: (1) Only backshear mode exists in the instability of longshore current for slope 1:40 and frontshear and backshear modes may exist slope 1:100. (2) The peaks of linear instability growth mode for slope 1:100 correspond to three cases: the dominant peak is formed by the joint action of both frontshear and backshear, or by backshear alone without the existence of the smaller peak or formed by either the frontshear or backshear. (3) Bottom friction can decrease the corresponding unstable growth rate but it cannot change the unstable fluctuation period. The results of fluctuation period, wavelength and spatial variation obtained by the analysis of linear shear instability are in good agreement with experimental results.     

“旅游+”背景下的美丽乡村规划编制探讨——以滨州惠民夹河村为例

随着我国发展全域旅游口号的提出,乡村旅游业开始进入发展的黄金期,保持了健康、持续、快速的发展态势。针对乡村旅游快速发展的现状,如何编制村庄规划成为关注的重点。该文通过滨州市夹河村规划实践,探讨了在"旅游+"背景下,如何营造村庄特色,发展乡村旅游,以期为其他地区的类似规划提供参考。     

赣江流域多种数据同化方案的径流模拟比较

为了探讨水文模型在不同水文数据同化方案下的径流模拟差异,本文采用集合卡尔曼滤波算法,以遥感蒸散发产品、实测径流为观测数据,构建了基于新安江模型的数据同化框架。基于此框架设计了4种不同同化方案(DA-ET、DAET(K)、DA-ET-Q、DA-ET-Q(K))以及1种对照方案OL,以赣江流域开展实例研究,评估了水文数据同化中遥感蒸散发产品的时间分辨率、模型蒸散发相关参数时变与否以及多源数据同化对径流模拟的影响。结果表明:在DA-ET方案下,同化两种不同时间分辨率的蒸散发产品均能提高模型整体的径流模拟精度,且时间分辨率更高的产品的同化效果更好;在DA-ET方案的基础上,考虑加入实测径流进行同化能够提升模型径流模拟精度,且DA-ET(K)与DA-ET-Q(K)方案所得径流相对误差的减幅均超过了20%,说明在蒸散发同化过程中同时考虑蒸散发参数动态变化的结果更优;相较于OL方案,4种同化方案均能不同程度地提高模型对径流高水部分的模拟能力,但DA-ET-Q(K)方案表现最差,而其余方案差异并不显著。本研究有助于进一步了解不同数据同化方案在径流模拟中的差异,从而为水资源高效利用与科学管理提供科学依据...     

勘探平硐施工技术与掘进装备发展现状

平硐勘探是在进行水利水电勘察时,获取山体周围区域的地质参数,全面了解地层情况的一种技术手段。在勘查工作中,首先的目标是查明建筑物的工程地质条件或特殊的地质问题,如断层、夹层等,并进行现场的原位测试和试验。因此,平硐勘探施工技术在重要工程勘察中占据十分重要的地位。如何加快施工进度、缩短工期、解决平硐施工中的难题是这项技术主要的研究方向。目前,平硐的施工工艺和掘进装备已有一定的发展,但是针对勘探平硐开拓技术和相关专用装备的研究仍处于起步阶段。本文主要论述了平硐施工工艺和掘进装备的发展现状,分析其特点及局限性,将不同施工方法的综合性能进行对比,并针对勘探平硐技术发展的实际问题进行分析,探讨了钻孔劈裂方法在勘探平硐中的优势以及适用性,最后基于施工工艺对勘探平硐掘进装备的发展方向进行了展望。     

Reconstruction of nearshore chemical conditions in the Mesoproterozoic: evidence from red and grey beds of the Yangzhuang formation,North China Craton

ABSTRACT

Mesoproterozoic red beds near ancient coasts have not aroused extensive interest. A new geochemical study of the alternating red and grey dolostones from the Yangzhuang Formation provides a better understanding of the redox conditions of nearshore sedimentary environments. In this contribution, whole-rock samples are characterized by positive correlations of rare earth elements (REE) vs. Th and Fe_T vs. Th and flat-type REE distribution patterns, indicating massive terrigenous input, which is considered to be inherited from felsic rocks. Relatively high (Fe_mag+Fe_ox)/Fe_T and Fe³⁺/Fe²⁺ ratios in red beds indicate more oxidized conditions in supratidal environments compared with the lower oxygen contents in intertidal environments. Under these two distinct chemical sedimentary conditions, acetic acid-leached red and grey samples both have HREE-depleted distributions, suggesting significant freshwater invasion. Moreover, limited terrigenous redox-sensitive elements (RSEs) can reach the coast where the red beds are deposited, whereas relatively high RSE enrichment factors originating from shallow oceans are recorded in grey beds. In the Mesoproterozoic, limited oxidative weathering, shallow seawater desalination, and low organic production occurred near the coast. Meanwhile, a prolonged period of low Mo and U availability preserved in carbonate minerals confirmed that marine oxygen levels failed to satisfy the deposition of offshore red beds. During the regression, potentially exposed sediments connected to atmospheric oxygen guaranteed the oxidation of iron and the formation of red beds, and these events were coupled with negative δ¹³C_carb shifts in the Yanliao rift zone.     

四川盆地震旦系灯影组不同古地理环境下丘滩储集体的差异性*

四川盆地震旦系灯影组丘滩沉积体广泛发育,具有很好的储集价值。基于露头勘查与岩心观测获取的资料,通过薄片鉴定、孔隙度、渗透率测试等方法分析丘滩储集体的储集性能。结果表明,由于震旦纪末期绵阳—长宁裂陷槽的发育影响了灯二段与灯四段碳酸盐岩台地相带展布,导致形成不同的古地理环境,目前可识别出高能环境、过渡环境、低能环境下发育的丘滩岩石类型,即以胡家坝剖面灯四段为代表的并进型丘滩多沉积高能环境岩石类型,以杨坝剖面灯二段为代表的追补型丘滩多沉积过渡环境岩石类型,以福成剖面灯四段为代表的饥饿型丘滩多沉积低能环境岩石类型。通过分析3种丘滩类型的储集空间与经历的准同生期成岩作用,并比较它们的物性特征,认为并进型丘滩体为最好的储集层。该研究成果有助于寻找优质储集层的发育位置,进而为四川盆地灯影组油气勘探提供参考。