Semidiurnal Dynamics of Salinity, Nutrients and Suspended Particulate Matter in an Estuary in the Seto Inland Sea, Japan, during a Spring Tide Cycle

The physical and chemical variability of the water column at subtidal station of an estuary in the Seto Inland Sea, Japan, was studied over a 24-hour period during a spring tide (tidal range ca. 2 m) in May 1995. Surface water and several depths through the water column were monitored every one and two hours, respectively. At each occasion, water temperature, salinity and dissolved oxygen concentration were measured and water samples were collected for the determination of nutrients and suspended particulate matter (SPM). Disruptive changes in the physical and chemical characteristics of the water was produced by the tidal cycle and the mixing of water masses of different origin. These changes were highly significant both spatially and temporally, yet with varying effects on physical parameters, nutrients and the different components of SPM. Significant differences in nutrient concentrations were also observed when the data-set was divided into ebb and flood components, irrespective of the depth. Nitrate and nitrite rose to 1.8 times higher during the flood. Spatial differences of SPM were less marked than those of nutrients, only particulate organic carbon (POC) being significantly higher at the surface than in the intermediate and the lower layer. Both POC and pheopigment concentrations increased markedly through the water column, being highest shortly before the lower low tide. In contrast, suspended solid (SS) content increased sharply after the lower low tide (>40 mg l⁻¹) and this coincided with a marked decrease of the C/SS content (<20 mg g⁻¹). The lagtime between POC and SS tidal transport was caused by particle resuspension from the exposed intertidal sediments as the tidal level rose, and particle transport selection in relation to the tidal state. This revised version was published online in August 2006 with corrections to the Cover Date.     

塔东地区古城4井上寒武统—中、上奥陶统流体地球化学示踪

通过对塔东地区古城4井上寒武统和中、上奥陶统碳酸盐岩围岩及充填物的碳、氧、锶同位素地球化学和流体包裹体成分的对比研究表明,充填于中、上奥陶统和上寒武统的流体分属于2个不同来源的流体体系。充填于中、上奥陶统灰岩裂缝中方解石脉的w(87Sr)/w(86Sr)介于0.7084~0.7088,它与早奥陶世海水的w(87Sr)/w(86Sr)相近;流体体系为CH4-H2O体系;充填物与围岩间具有明显的碳、氧同位素差异,表明上部流体体系中的流体来自于奥陶系地层本身。上寒武统白云岩裂缝中方解石脉的w(87Sr)/w(86Sr)为0.7138,明显地高于同时代海水的锶同位素值;流体体系为CO2-H2O体系;下部流体体系中的流体为外来富锶流体。上、下流体体系间互不连通暗示着上寒武统地层具有相对较好的保存条件。     

国内外城市雨水径流水质的研究

综合国内外综合资料,对城市不同建筑材料屋面和不同路面的雨水径流水质特征进行了对比分析,阐明了影响城市雨水径流水质的三大因素,并论述了城市雨水收集利用的现实意义。     

Carbon and oxygen isotopic composition of car- bonate cements of different phases in terrigenous siliciclastic reservoirs and significance for their origin： A case study from sandstones of the Triassic Yanchang Formation, southwestern Ordos Basin, China

Early carbonate cements in the Yanchang Formation sandstones are composed mainly of calcite with relatively heavier carbon isotope （their δ^18O values range from -0.3‰- -0.1‰） and lighter oxygen isotope （their δ^18O values range from -22.1‰- -19.5‰）. Generally, they are closely related to the direct precipitation of oversaturated calcium carbonate from alkaline lake water. This kind of cementation plays an important role in enhancing the anti-compaction ability of sandstones, preserving intragranular volume and providing the mass basis for later disso- lution caused by acidic fluid flow to produce secondary porosity. Ferriferous calcites are characterized by relatively light carbon isotope with δ^13C values ranging from -8.02‰ to -3.23‰, and lighter oxygen isotope with δ^18O values ranging from -22.9‰ to -19.7‰, which is obviously related to the decarboxylation of organic matter during the late period of early diagenesis to the early period of late diagenesis. As the mid-late diagenetic products, ferriferous cal- cites in the study area are considered as the characteristic authigenic minerals for indicating large-scaled hydrocarbon influx and migration within the clastic reservoir. The late ankerite is relatively heavy in carbon isotope with δ^13C values ranging from -1.92‰ to -0.84‰, and shows a wide range of variations in oxygen isotopic composition, with δ^18O values ranging from -20.5‰ to -12.6‰. They are believed to have nothing to do with decarboxylation, but the previously formed marine carbonate rock fragments may serve as the chief carbon source for their precipitation, and the alkaline diagenetic environment at the mid-late stage would promote this process.     

Environmental Redox Changes of the Ancient Sea in the Yangtze Area during the Ordo-Silurian Transition

Extensive organic-matter （OM） rich facies （black shales） occur in the Ordo-Silurian boundary successions in the Yangtze area, South China. To investigate the redox changes of the Yangtze Sea during the Ordo-Silurian transition, two OM sections （Wangjiawan in Yichang, Hubei Province, and Sanjiaguan in Zhangjiajie, Hunan Province） straddling the Ordo-Silurian boundary are studied. The measurements finished in this study include contents of the total organic carbon （TOC）, pyrite sulphur, and different species of Fe, including dithionite-extractable Fe （FED）, pyrite Fe （FeP）, HCl-extractable Fe （FeH）, and total Fe （FeT）, in black shales, as well as other redox proxies, such as the SIC ratio, the ratio between highly reactive Fe （FeHR = FeD ＋ FeP） and FeT, and the FeP/（FeP ＋ FeH） ratio, known as the degree of pyritization （DOP）. In the Wangjiawan section, the Middle Ashgill sediments have high FeHR/FeT ratios （0.20-0.77; avg. 0.45）, high DOP values （0.21-0.72; avg. 0.54）, and a relatively constant sulfur content independent of the organic carbon content. By the contrast, the mid-early Hirnantian deposits generally have low FeHR/FeT ratios （0.10-0.35; avg. 0.21）, low DOP values （0.11- 0.40; avg. 0.28）, and SIC values are clustering on the normal marine value （SIC = 0.36）. The late Hirnantian and early Rhuddanian deposits, similar to those of the Middle Ashgill deposits, are characterized by high FeHR/FeT ratios （0.32-0.49; avg. 0.41）, high DOP values （0.46-0.68; avg. 0.53） and fairly constant sulfur contents. These data suggest the occurrences of marine anoxia on the Yangtze Sea shelf during intervals of the Mid Ashgill, Late Hirnantian and Early Rhuddanian, and ventilated and oxygenated marine conditions during the mid-early Hirnantian time. The mid-early Hirnantian ventilated event was concomitant with the global glacial period, likely resulted from the glacio-eustatic sea-level fall and subsequent circulation of cold, dense oxygenated waters     

禹城市城乡用地结构和布局分析

统筹城乡用地、优化城乡用地结构和布局,既是节约和集约用地的重要途径,又是统筹城乡发展的客观需要。通过分析禹城市城乡用地结构和布局,提出优化城乡用地结构和布局的建议和对策,从而为制定合理的土地利用总体规划提供基本的依据。     

大民屯凹陷烃源岩有机质丰度的恢复

烃源岩有机质丰度的恢复具有重要的现实和理论意义。笔者在对比多种方法的基础上,对大民屯凹陷的烃源岩的有机质丰度进行了恢复。     

加强地理信息资源建设和开发利用的思考

地理信息资源的建设和开发利用在准确掌握国情国力、提高管理决策水平、管理社会公共事务、处理经济社会发展等重大问题中将发挥越来越重要的作用。本文在对发改委、测绘、国土、环境保护等部门进行调研的基础上,从我国地理信息的获取和利用现状、地理信息资源建设和开发利用政策法规的制定、产业发展以及国家安全等四个方面进行了研究,并提出了建议。     

开发利用好水利信息资源为水利信息化打下坚实基础

信息资源是行业最重要的资源之一。开发利用信息资源既是行业信息化的出发点,又是行业信息化的归宿。对于水利这一个信息密集型行业,需要逐步实现水利信息化,充分利用现代信息技术,深入开发和广泛利用水利信息资源,利用水利信息化推动水利现代化。     

基于规则库和网格算法的土地利用现状图自动数字注记

图形自动注记可极大地提高制图的工作效率。针对土地利用现状图数字注记的特点,本文从地图认知角度出发,建立注记自动配置的规则库,提出面状要素自动注记的一种新的算法——网格法。该算法最大的优点是容易实现、效率高,可方便地解决注记压盖冲突等问题。通过开发一个程序实例,对图斑要素进行了自动数字注记,实验表明95％以上的图形注记效果都较为理想。