红枫湖夏季分层期间pCO2分布规律的研究

在夏季分层期间对红枫湖南、北湖湖心的水样进行分层采集,同时测定了分层水样的温度、pH、HCO₃-浓度、溶解氧(DO)、叶绿素a(Chl-a)及铵根离子(NH₄+)、硝酸根离子(NO₃-)、磷酸根离子(PO₄3-)的浓度,水体中CO₂的分压(pCO₂)由化学平衡及亨利定律求得。研究结果表明:光合作用、有机质降解及水体热分层是影响红枫湖夏季pCO₂分布的主要因素。其中,温水层CO₂欠饱和是光合作用吸收CO₂引起的,温跃层中pCO₂的急剧增加是光合产物降解产生CO₂引起的。静水层沉积物附近pCO₂最高并且还有持续增加的趋势,说明沉积物中有机质降解是静水层中CO₂增加的主要原因,夏季湖底水温较高加快了沉积物中有机质的降解。分层现象使pCO₂在水体中的分布差别明显,并且使静水层中CO₂得到积累。此外,夏季红枫湖水体中pCO₂的变化与NH₄+、PO₄3-的变化密不可分,表现为温水层中光合作用消耗NH₄+、PO₄3-,有机质降解过程伴随NH₄+、PO₄3-的释放。     

含盐量对松嫩平原碳酸盐渍土抗剪强度的影响

松嫩平原分布着大量的碳酸盐渍土,其不良的工程性质给穿越其中的道路质量造成不同程度的影响。由于盐渍土所含易溶盐成分主要为碳酸氢钠,该研究通过向碳酸盐渍土内加入碳酸氢钠制备不同含盐量的盐渍土,进行室内直剪试验。试验表明：随着含盐量的增加土的粘聚力减小,内摩擦角有先减小后变大的趋势;随着含水量的增加,土的含盐量越高,土的粘聚力减小越明显。易溶盐在土中的状态形式是影响其抗剪强度参数变化的一个重要原因。     

三维城市模型在城镇地籍管理中的应用

地籍管理是土地管理的基础,是国家依法管理土地权属、保护土地所有者和使用者合法权益而采取的行政措施。本文针对当前地籍管理中二维宗地图常因界址不明而引发土地纠纷的现状,在城镇地籍管理中引入了表达直观的三维城市模型。三维空间的交互浏览、界址点、界址线与三维城市模型的叠加、宗地信息的查询以及三维宗地图的制图输出改变了传统地籍管理的模式,在实践中取得了较好的效果,是未来城镇地籍管理的一种重要手段。     

基于ArcScene的建筑物日照分析模块的设计与实现

介绍了利用ArcObjects开发、基于ArcScene的建筑物日照分析模块的研制,对各个子模块作了介绍。特别对涉及到的日照分析技术、阴影动态显示、3维建筑设计等技术做了详细的说明。最后对该模块的应用做了简要演示。     

浅析省级基础测绘数据在城市建模中的应用

利用基础测绘数据中房屋数据获取和编辑的方法,探讨1:10 000基础测绘数据中的建筑物在城市地理信息服务和建模中的应用以及目前基础测绘数据与城市建模数据间的差距.     

哈尔滨市用地查询分析系统的设计与实现

随着3S技术的不断发展,客户要求的不断提高,原始的服务方式已经不能满足客户对多元信息获取的需要,在这样的背景之下,哈尔滨市用地查询分析系统应运而生,它的成功研制有效解决了客户需求,并对其他项目数据整合的方式与方法提供了有益的解决方案。     

工程勘察数据的传递控制与可视化

从广义说,工程勘察成果中的很大一部分是通过大量数据的传递与处理取得的。数据传递结构的优化和合理控制是提高勘察效率和质量的保证。讨论了用程序编制的方法实现的数据从平面图到剖面图的钻孔距离传递,利用模糊聚类思想提出的对剖面数据进行合并的建议和利用地质三维软件实现的三维地质体模型的耦合展示,这几个问题正是目前大多勘察单位在数据控制与传递流程中可能欠缺的环节。     

PDSOFT 3DPiping在工程设计中的应用

介绍了PDSOFT3DPiping三维配管软件在脱盐水站项目工艺配管设计中的应用,应用软件的主要步骤,及其在工程设计中的优越性。PDSOFT3DPiping三维配管软件不仅能提高设计效率和设计质量,也能减少设计中出现的问题。     

Determination of Sr/Sr mass-dependent isotopic fractionation and radiogenic isotope variation of Sr/Sr in the Neoproterozoic Doushantuo Formation

We measured both mass-dependent isotope fractionation of δ⁸⁸Sr (⁸⁸Sr/⁸⁶Sr) and radiogenic isotopic variation of Sr (⁸⁷Sr/⁸⁶Sr) for the Neoproterozoic Doushantuo Formation that deposited as a cap carbonate immediately above the Marinoan-related Nantuo Tillite. The δ⁸⁸Sr and ⁸⁷Sr/⁸⁶Sr compositions showed three remarkable characteristics: (1) high radiogenic ⁸⁷Sr/⁸⁶Sr values and gradual decrease in the ⁸⁷Sr/⁸⁶Sr ratios, (2) anomalously low δ⁸⁸Sr values at the lower part cap carbonate, and (3) a clear correlation between ⁸⁷Sr/⁸⁶Sr and δ⁸⁸Sr values. These isotopic signatures can be explained by assuming an extreme greenhouse condition after the Marinoan glaciation. Surface seawater, mixed with a large amount of freshwater from continental crusts with high ⁸⁷Sr/⁸⁶Sr and lighter δ⁸⁸Sr ratios, was formed during the extreme global warming after the glacial event. High atmospheric CO₂ content caused sudden precipitation of cap carbonate from the surface seawater with high ⁸⁷Sr/⁸⁶Sr and lighter δ⁸⁸Sr ratios. Subsequently, the mixing of the underlying seawater, with unradiogenic Sr isotope compositions and normal δ⁸⁸Sr ratios, probably caused gradual decrease of the ⁸⁷Sr/⁸⁶Sr ratios of the seawater and deposition of carbonate with normal δ⁸⁸Sr ratios. The combination of ⁸⁷Sr/⁸⁶Sr and δ⁸⁸Sr isotope systematics gives us new insights on the surface evolution after the Snowball Earth.     

Geochemical Eccentricity of Ground Water Allied to Weathering of Basalts from the Deccan Volcanic Province,India: Insinuation on CO<Subscript>2</Subscript> Consumption

Analyses of 72 samples from Upper Panjhara basin in the northern part of Deccan Plateau, India, indicate that geochemical incongruity of groundwater is largely a function of mineral composition of the basaltic lithology. Higher proportion of alkaline earth elements to total cations and HCO₃>Cl + SO₄ reflect weathering of primary silicates as chief source of ions. Inputs of Cl, SO₄, and NO₃ are related to rainfall and localized anthropogenic factors. Groundwater from recharge area representing Ca + Mg–HCO₃ type progressively evolves to Ca + Na–HCO₃ and Na–Ca–HCO₃ class along flow direction replicates the role of cation exchange and precipitation processes. While the post-monsoon chemistry is controlled by silicate mineral dissolution + cation exchange reactions, pre-monsoon variability is attributable chiefly to precipitation reactions + anthropogenic factors. Positive correlations between Mg vs HCO₃ and Ca + Mg vs HCO₃ supports selective dissolution of olivine and pyroxene as dominant process in post-monsoon followed by dissolution of plagioclase feldspar and secondary carbonates. The pre-monsoon data however, points toward the dissolution of plagioclase and precipitation of CaCO₃ supported by improved correlation coefficients between Na + Ca vs HCO₃ and negative correlation of Ca vs HCO₃, respectively. It is proposed that the eccentricity in the composition of groundwater from the Panjhara basin is a function of selective dissolution of olivine > pyroxene followed by plagioclase feldspar. The data suggest siallitization (L < R and R _k) as dominant mechanism of chemical weathering of basalts, stimulating monosiallitic (kaolinite) and bisiallitic (montmorillonite) products. The chemical denudation rates for Panjhara basin worked out separately for the ground and surface water component range from 6.98 to 36.65 tons/km²/yr, respectively. The values of the CO₂ consumption rates range between 0.18 × 10⁶ mol//km²/yr (groundwater) and 0.9 × 10⁶ mol/km²/yr (surface water), which indicates that the groundwater forms a considerable fraction of CO₂ consumption, an inference, that is, not taken into contemplation in most of the studies.