An evaluation of the health status of the Lavaca Bay, Texas ecosystem using Crassostrea virginica as the sentinel species

Locational risks for compromised ecosystem health for the eastern oysters (Crassostrea virginica) harvested from Lavaca Bay, Texas were estimated. Flow cytometric evaluation of variations in DNA content and the lysosomal destabilization assay were used for evaluation of genotoxicity and stress, respectively. Bayesian geo-statistical methods were utilized to estimate and evaluate spatial effects. For models with spatial risks, continuous surface maps of predicted parameter values were created to evaluate risk location. Lysosomal destabilization assay results were spatially oriented whereas flow cytometry results were fit best with the random effects model. While not spatially oriented, the highest levels of variations in DNA content were also present near industrial facilities. Locational risks of increased biomarkers of genotoxicity and stress in the eastern oyster (Crassostrea virginica) were increased with proximity to industrial facilities     

A heat perturbation flow meter for application in soft sediments

A prototype flow meter has been developed, based upon the heat perturbation principle, to monitor groundwater specific discharge in soft sediments. The device is designed for use in spatially intensive, long-term monitoring campaigns in remote or inconvenient locations, and is cheap, robust and capable of being logged automatically. The results of the laboratory tests indicate that the heat perturbation principle is suitable for determining the magnitude of specific discharge to a degree of accuracy that would be useful in practical applications in dynamic groundwater systems with rapidly changing flows of approximately 1 md⁻¹ or more and that the groundwater flow direction can generally be determined to a high level of precision. The accuracy and reliability of the estimates of specific discharge have been shown to depend strongly upon the geometrical precision of manufacture and the quality of the temperature monitoring system. These factors become most significant in the estimation of lower flows and further investigation is required to determine the detection limit of the device. Specific discharge estimates have been shown to be insensitive to dispersivity values appropriate to the scale of the device. Unlike the majority of heat perturbation devices, calibration is unnecessary.     

Stream Temperature Trends in Turkey

Stream temperature is an important property of water and affects most other water quality constituents. It is also a property which is very much influenced by exogenous factors like air temperature and stream flow. This study investigates long‐term trends in stream temperatures measured at various stream monitoring stations in Turkey to better understand links with climate change. It was found by statistical trend analysis that more streams have experienced decreasing trends than increasing ones. Moreover, stream temperatures show a rising tendency in most stations over Turkey. Flow‐adjusted temperatures were computed to eliminate flow dependency and these show more positive than negative trends. Management plans of streams and watersheds need to take this into account and incorporate the implications into plans.     

黄河中上游能源基地区岩溶大泉衰减原因、变化趋势及其防治对策

黄河中上游地区,自黄河青铜峡,经内蒙准格尔、山西、陕西两省至河南西部,为我国最重要的以煤炭资源为主的能源基地。随着能源基地的建设和开发,区域岩溶地下水水位连年持续下降,岩溶泉水流量衰减,引起了一系列环境地质问题,如水质恶化、生态退化等。本文从能源基地岩溶泉流量衰减问题入手,研究了能源基地区岩溶泉水流量衰减问题,提出了开展水土保持工作、合理控制地下水的开采、搞好矿坑水的综合利用及污水处理资源化等相应的防治对策。      

Numerical modelling of strain in lava tubes

Received: 5 November 1998 / Accepted: 17 November 1999     

Unified modeling of flow liquefaction and cyclic mobility

Flow liquefaction and cyclic mobility are two different phenomena that are encountered during strong earthquakes. Flow liquefaction is associated with the contractive behavior of loose granular materials and cyclic mobility is associated with the dilative response of both loose and dense granular materials at low confining stresses. These two types of response pertain to the same material and therefore should be modeled in a consistent manner. Whether a soil in a given state exhibits contractive or dilative behavior is dependent on its dilatancy, d=d_v^p/d_q^p. A form of the dilatancy d=d(η,ψ,C) is proposed, where η=q/p is the stress ratio, and ψ and C denote the internal state variables and the intrinsic properties, respectively. It has been shown that such a state-dependent dilatancy is effective in describing both the contractive and dilative behavior. This allows the soil behavior associated with flow liquefaction and cyclic mobility during earthquakes to be modeled in a unified way.     

油井产液量与井底压力关系的研究

利用流体动力学理论,研究了油井产量与井口压力、井底压力之间的产量关系,给出了井口压力和油井产液量之间的等效互换关系,进一步研究了油井动态观测资料的科学处理方法,以胜利油田东水－３井为例,对其观测资料进行了处理,并讨论了泄流管管径对流量及等效水位的影响。     

动因与机制——对旅游地社会文化环境变迁理论的研究

制约旅游地社会文化环境变迁的动因主要在于外界旅游流对旅游地的静态平衡系统产生冲击和干扰,分析旅游地社会文化环境变迁,必须从构成"流"的要素入手;旅游者及其携带而来的物能流与旅游地各主体要素(政府机构、旅游企业、旅游地原生居民等)的竞争与协调产生旅游地社会文化环境变迁的动力机制.     

岩石圈流变实验研究的进展

岩石高温高压变形实验是了解地球内部物质流动特性的最直接的手段 .本文概述了近年来岩石流变实验研究的一些成果 ,重点总结了水和部分熔融对上地幔顶部橄榄石流变行为的影响 ,以及地壳多相岩石流变实验研究的一些成果 .     

持续大流量过程对黄河内蒙古河段河道塑形能力的分析与思考

2018年伏秋汛期黄河流域上游持续来水,为保证2108-2019年度黄河流域凌汛期安全,黄河流域重点水库进行了大流量持续下泄。以2018年9月的实际数据为基准,通过对重点水库实际日均出入库调度情况,内蒙古河段的重点水文站实际日均流量过程和三个年份汛期大断面套绘成果对比分析研究,可以得出水库大流量持续下泄对内蒙古河段河道塑形能力起到了关键性作用,有效的提高了主槽过流能力,河段最小平滩流量得到一定的恢复,对下一步研究黄河流域河道过流能力提供了有利的数据支撑和参考价值。