2015-2019年武汉市湖泊水质时空变化

为探究“十三五”期间武汉市湖泊水质变化特征及规律,分析当前武汉市湖泊水环境的主要问题及成因,为武汉市水生态环境保护“十四五”规划提供科学支撑,以武汉市166个湖泊为研究对象,根据武汉市环境监测中心2015-2019年对各个湖泊的监测数据,采用水质综合污染指数、富营养化状态评价、动态度分析等方法,对武汉市湖泊水环境进行综合评价.结果表明：1）2015-2019年武汉市湖泊水质总体好转,2019年全市湖泊综合污染指数较2015年下降7.74%,多数湖泊营养状态呈现稳中向好趋势,但湖泊水质较难实现持续改善.2）武汉市湖泊主要超标污染物总磷、氨氮、化学需氧量和高锰酸盐指数平均质量浓度在2015-2019年间均呈下降趋势,但2019年有47%湖泊总磷浓度劣于Ⅳ类评价标准,磷元素是制约湖泊水质的主要因素.3）2015-2019年武汉市中心城区湖泊综合污染指数下降,湖泊富营养化状态好转,但青山北湖、南湖等湖泊综合污染指数较高,排口排污、底泥内源污染是影响中心城区湖泊水质的主要因素.新城区湖泊水质改善仍面临一定压力,东西湖水系重度富营养化湖泊数量增多,后湖水系湖泊综合污染指数上升,农业面源、工业生产对新城区湖泊水质影响较大,湖泊破碎化导致的自净能力降低也是影响湖泊水质的重要因素.     

城市化对平原河网水系结构及功能的影响——以苏州市为例

针对城市化对平原河网水系结构的影响所引起的洪涝灾害频发等一系列水文问题,以我国典型平原河网地区苏州市为例,根据不同城市化程度分为主城区、市辖区、其他市县区,基于1991、2001和2015年三期遥感影像与1960s、1980s和2010s三个时期的水系数据,应用RS/GIS等技术,构建水系结构参数指标,重点探讨了城市化对河网水系结构及功能的影响.结果表明：城镇用地迅速增长,主要以牺牲水田、水域等土地利用方式为代价,到2015年全区城镇用地面积所占比重已达到41.35%,土地利用类型的变化规律与城市化进程的差异性保持一致;水系结构变化主要受城市化影响,且基本与城市化进程呈现同步性.近50年来,全区的水面率、河网密度、支流发育系数、主干河流面积长度比、河网复杂度和河网结构稳定度分别减少了19.63%、6.91%、7.34%、1.06%、5.49%和7.87%,城市化水平与各指数均呈负相关关系;人类活动不仅直接影响河流功能,也间接地通过改变平原河网的水系结构导致其功能发生改变,如河网调蓄能力下降、河流生态功能受损等.该研究为城市化地区河流水系保护及防洪减灾提供参考与理论支撑.     

气候变化对闽东粮食产量影响分析

气候变化对粮食产量具有重要的影响作用,加强气候变化对粮食产量影响分析和风险评估,对应对气候变化、进行粮食生产结构合理调整和保障粮食安全具有重要的意义。为此,应用部分经验公式,推导出了一种计算粮食气候产量评价模式,用以估测气候因子(气温、降水)变化对粮食产量的影响。利用该模式,根据1981—2010年闽东地区逐年气温降水推算粮食产量,运用聚类分析、概率函数拟合等统计学方法对粮食产量时间序列进行分析。结果表明,闽东粮食产量与气温相关不显著,而与降水量显著相关。降水的增加有利于产量的增加。气温升高,在一定条件下,有利于产量增加,但达到一定程度后,气温升高,却可能造成产量的降低。聚类分析闽东粮食产量年型可分为歉收年、正常略少年、正常略多年和丰产年,闽东粮食产量主要年份为正常略少或略多,大多数年份粮食产量较为稳定,粮食产量评价结果与历史实况较为一致。本文推算的粮食产量评价模式能够反映出不同气候年景对产量的变化影响,是一种较为便捷和实用的气候变化对粮食产量的评估方式。     

基于雷达资料同化的飑线过程数值模拟试验研究

利用中尺度WRF模式及其3DVAR 同化系统对2014年3 月30 日发生在我国华南地区的一次飑线过程展开多普勒天气雷达资料的同化效果试验研究.首先对雷达资料进行去地物杂波、退速度模糊等预处理,后设计了基于不同雷达观测量的同化试验及同化频次的敏感性试验.结果表明:直接循环同化雷达径向风资料和雷达反射率因子能够增加数值模...     

全国综合气象信息共享平台架构设计技术特征

全国综合气象信息共享平台（CIMISS）是依托天气雷达数据共享平台工程项目建成的国省统一数据环境,实现各类气象数据的规范管理,直接支撑气象业务应用。该文介绍了CIMISS架构设计及核心内容,结合业务应用效果的实例分析,阐述架构设计如何有效提升数据和应用的集约高效。借鉴企业架构（EA）方法,建立了业务架构、数据架构、应用架构、技术架构和标准规范体系。采用一系列架构优化设计,包括实现元数据统一管理同步、数据质量控制、统一业务监控、异构数据库统一数据服务、优化信息流程、分层设计和集群技术应用等,满足CIMISS标准性、扩展性、稳定性等需求,获得良好的全流程数据服务时效,核心资料接收入库总耗时均小于3 min,数据访问效率较国家级气象资料存储检索系统提升2~5倍。继承现有CIMISS架构设计成果,正在设计中的气象大数据平台整体技术架构将向云平台、分布式存储等新技术升级。     

Abandoned channel fill sequences in the tidal estuary of a small mountainous,dry‐summer river

This study proposes a modification of the current model for abandoned channel fill stratigraphy produced in unidirectional flow river reaches to incorporate seasonal tidal deposition. Evidence supporting this concept came from a study of two consecutive channel abandonment sequences in Ropers Slough of the lower Eel River Estuary in northern California. Aerial photographs showed that Ropers Slough was abandoned around 1943, reoccupied after the 1964 flood, and abandoned again in 1974 with fill continuing to the present. Planform geomorphic characteristics derived from these images were used in conjunction with sub‐centimetre resolution stratigraphic analyses to describe depositional processes and their resultant sedimentary deposits. Both abandonment sequences recorded quasi‐annual scale fluvial/tidal deposition couplets. In both cases, tidal deposits contained very little sand, were higher in organic and inorganic carbon content than the sandier, fluvially dominated deposits, and possessed millimetre‐scale horizontal laminations. The two abandonment fills differed significantly in terms of the temporal progression of channel narrowing and fluvial sediment deposition characteristics. Aerial photographic analysis showed that the first abandonment sequence led to a more rapid narrowing of Ropers Slough and produced deposits with a positive relationship between grain size/deposit thickness and discharge. The second abandonment resulted in a much slower narrowing of Ropers Slough and generally thinner fluvial deposits with no clear relationship between grain size/deposit thickness and discharge. The δ¹³C values and organic nitrogen to organic carbon ratios of deposits from the first phase overlapped with Eel River suspended sediment characteristics found for low flows (one to five times mean discharge), while those of the second phase were consistent with suspended sediment from higher flows (seven to ten times mean discharge). When considered together, the results indicate that the early fill sequence recorded a reach experiencing regular fluvial deposition through flow conditions during the wet season, while the latter fill sequence records a reach more disconnected from the main stem in terms of flow and sediment. The major factor affecting the difference in sedimentation between the two fill periods appears to have been the morphology of the upstream river bend in relation to the position of the bifurcation node. During the first fill period, the upstream entrance to Ropers Slough seems to have remained open, in part due to the placement of its entrance on the outside of the mainstem river bend, and despite stronger tidal effects caused by a larger tidal prism and closer proximity to the tidal inlet. By the second fill sequence, the upstream bend morphology had altered, placing the entrance to Ropers Slough on the inner bank of the mainstem bend, which resulted in more rapid plug bar formation. The role of tidal effects in the geomorphic trajectory of the two abandonment sequences is unclear, but appears to have been less important than local bifurcation geometry.     

毛乌素沙地南缘凝结水观测实验分析

采用称重法对2007年8月期间毛乌素沙地南缘不同地表类型（改良沙地、生物结皮、物理结皮和流沙）、沙丘不同部位的凝结水形成动态过程进行了系统观测。结果表明：改良沙地凝结水量达0．206mm／d,显著大于生物结皮、物理结皮和流沙,生物结皮凝结水量为0．100mm／d,显著高于流沙,而其他两者之间凝结水量无显著性差异;沙丘不同部位凝结水量差异显著,丘间地凝结水量最大,沙丘坡面次之,沙丘顶部最少,日凝结水量分别为0．0873mm／d、0．0768mm／d和0．0674mm／d;从凝结水形成过程看出凝结水一般在每天17：00产生,次日7：00结束,在夜晚21：00和凌晨3：00左右出现2个凝结水较大值;凝结水的形成与气象因子密切相关,凝结水量与地表温度、大气和地表温度差以及净辐射具有显著相关性。     

Microbial Mats in the Mesoproterozoic Carbonates of the North China Platform and Their Potential for Hydrocarbon Generation

The well-preserved Mesoproterozoic succession in the North China platform consists mainly of three llthological associations including peritidal quartz sandstone, shallow marine and lagoonai dark to black shales, and shallow epeiric carbonates, with a total thickness of up to 8 000 m. In addition to well-documented microplants, macroalgae, and microbial buildups, abundant microbially induced sedimentary structures (MISS) and mat-related sediments have been recognized in these rocks. Intensive microbial mat layers and MISS are especially well preserved in the carbonates of the upper Gaoyuzhuang (高于庄) (ca. 1.5 Ga) and lower Wumishan (雾迷山) (ca. 1.45 Ga) formations, Indicating diversified microbial activities and a high organic production. In these petrified blomats, putative microbial fossils (both coccoidal and filamentous) and framboidal pyrites have been identified. The abundance of authigenic carbonate minerals in the host rocks, such as, acicular aragnnites, rosette barites, radial siderites, ankerites, and botryoidai carbonate cements, suggests authigenlc carbonate precipitation from anaerobic oxidation of methane (AOM) under anoxic/euxinic conditions. Warm climate and anoxic/euxinic conditions in the Mesoproterozoic oceans may have facilitated high microbial productivity and organic burial in sediments. Although authigenic carbonate cements may record carbonate precipitation from anaerobic methane oxidation, gas blister (or dome) structures may indicate gas release from active methanogenesls during shallow burial Bituminous fragments in mat-related carbonates also provide evidence for hydrocarbon generation. Under proper conditions, the Mesoproterozoic mat-rich carbonates will have the potential for hydrocarbon generation and serve as source rocks. On the basis of petrified biomats, a rough estimation suggests that the Mesoproterozoic carbonates of the North China platform might have a hydrocarbon production potential in theorder of 10×108t.     

35 Ma－An Important Natural Periodicity in Geological History： Concept of Natural Crisis and Its Possible Cause

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