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The 226 Ra and 228 Ra activities of Qinghai Lake surface water,groundwater,river water,suspended particles,and bottom sediments were measured in a gamma-ray spectrometer.The sources of 226 Ra and 228 Ra were discussed according to their distribution characteristics.226 Ra and 228 Ra activities(dpm/(100 L)) ranged from 14.13±0.22 to 19.22±0.42 and 17.72±0.66 to 30.96±1.47 in the surface water of the North Bay,respectively,and from 7.88±0.24 to 33.80±0.47 and 15.73±0.74 to 57.31±1.44,respectively,in the South Bay.The surface water near the estuary had a lower salinity and had a higher concentration of radium isotopes than the samples collected further away.The farther offshore the sample,the higher the salinity was,and the lower the radium isotope activity.The distribution of radium activities in the western part of Qinghai Lake is controlled by several factors,including Buha River runoff,desorption from suspended particles derived from the river,groundwater discharge,and a small amount of diffusion from the sediment. 相似文献
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辽东硼矿的成矿机制及成矿模式 总被引：7，自引：0，他引：7
为了解辽东硼矿的成矿机制及建立成矿模式, 分析了含硼岩系、镁质容矿岩石、区域变质作用及混合岩化作用、构造等四大控矿因素, 发现含硼岩系具富硼特征, 容矿岩石具富镁特点并可成为硼质的沉淀剂, 含硼岩系中硼在区域变质和混合岩化过程中得到进一步活化形成含硼热液, 含硼热液在有利的构造空间交代镁质岩石即可形成镁硼酸盐型硼矿.含硼岩系、镁质容矿岩石是硼矿形成的物质基础, 区域变质及混合岩化作用、构造活动是硼矿形成的必要条件.辽东硼矿成矿模式为原始火山-沉积初始富集和部分熔融含硼热液交代镁质岩石. 相似文献
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依据“建设用地地质灾害危险性评估技术要求”选择积分法对工程建设用地进行地质灾害危险性现状评估,结果认为：评估区的地质环境条件复杂程度属简单—中等类型,评估区现状地质灾害有崩塌灾害—种类型7处,属危险性小的级别,对其危险性起决定性作用的因素有：地形条件、地层岩性、构造与地震和人为活动。 相似文献
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建设用地地质灾害危险性评估中关键技术问题的探讨 总被引：6，自引：0，他引：6
根据“建设用地地质灾害危险性评估技术要求”中的原则,对建设项目(市政工程、铁路工程及其它)重要性进行了评估级别的划分。尝试确定了评估范围。提出危险性分区可根据评估区地质灾害危险性综合评价结果进行划分。 相似文献
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PRB技术在矿区地质填图及图件编绘中应用的几点尝试 总被引：2，自引：1，他引：1
运用PRB数字填图技术进行矿产地质填图及图件编绘的基本做法是:用手持GPS对地质点定位,并将坐标值及相关简单属性存于其中,用接收软件将存于GPS中的数据导出,然后在比较通用的软件如Excel.surfer8、Grapher4、CAD、Mapgis等软件中进行处理,最后在Mapgis中加挂属性,进行建库分析。实践过程中尚遇一些难题,如GPS的精度问题、地形图矢量化工作量大且各自为战、地质花纹及颜色填充混乱不统一等问题,有待于今后逐步完善。 相似文献
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Radionuclides (i.e., 7Be and 210Pb) can be used to trace particle and sediment dynamics and to quantify coastal oceanic processes with time scales ranging from a few days to a hundred years. Here, we study the settling dynamics of suspended particles and the implication by sedimentary heavy metals in the Wenjiao/Wenchang River and Wanquan River estuaries through the measurement of the particulate 7Be and 210Pb nuclides. Activity in the particulate phase had a range of 2.1–54.5 and 4.6–67.9 Bq kg−1 for 7Be and excess 210Pb (210Pbxs), respectively, in the Wenjiao/Wenchang River estuary. In the Wanquan River estuary, activity is in the range of 1.2–43.5 Bq kg−1 for 7Be and 6.2–194.5 Bq kg−1 for 210Pbxs. At the same time, activity in the dissolved phase had a range of 0.46–1.26 and 0.30–1.17 Bq m−3 for 7Be and 210Pb, respectively, in the Wenjiao/Wenchang River estuary; ranges of 0.10–2.31 and 0.09–1.87 Bq m−3 for 7Be and 210Pb, respectively, were observed in the Wanquan River estuary. The distribution coefficients (Kd) for the two nuclides decreased within increased in suspended particle matters (SPM) concentration and/or salinity in Wanquan River estuary. The residence times of particulate 7Be and 210Pbxs had ranges of 0.4–1.6 and 1.65–5.15 days, respectively, in the Wenjiao/Wenchang River estuary; and ranges of 0.02–3.2 and 0.61–4.44 days, respectively in the Wanquan River estuary. All residence times for the two nuclides increased in the seaward direction. In the Wenjiao/Wenchang River estuary, we found that 11.8–21.0% of Cu, 3.0–9.0% of Zn and 43.2–69.9% for Cd is removed from the water column and deposited into the estuary, and 24.2–34.8% for Cu, 7.2–23.8% for Zn, and 70.0–82.5% for Cd in the Wanquan River estuary, respectively. 相似文献
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快速城市化背景下,个体移动行为变得复杂多元,人类活动对于城市结构的影响和约束越来越大,产生了一系列人与城市互动过程中的问题.人的活动与移动如何改变城市结构以及如何被城市结构限制仍然缺乏有效的研究.论文利用城市时空大数据,以"活动—行为—结构"3个维度构建个体出行模式与城市空间结构交互的框架模型,研究个体的移动与活动模式,其与城市空间结构的交互影响机制. 相似文献
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234Th is widely used to quantify the magnitude of upper ocean particulate organic carbon(POC)export in oceans.In the present work,the rates of particulate organic carbon export were measured based on the distribution patterns of234Th/238U disequilibrium in the water column within the continental slope of the East China Sea(ECS)during May 2011.The profiles of particulate and dissolved234Th activities at all three stations showed a relative deficit with respect to238U in the upper 100 m of the water column.The dissolved234Th scavenging rates and the particulate234Th removal rates and their residence times were calculated by a one-dimensional steady state model.The results showed that the dissolved234Th scavenging rates and the particulate234Th removal rates ranged from 12.4–61.4 dpm/(m3·d)andfrom3.8–21.8 dpm/(m3·d),respectively.The residence times of dissolved and particulate234Th were in the range of 3.4–158 d and 63.7–96.5 d,respectively.Combined with the measurement of POC/234Th ratios of suspended particles,POC export flux(calculated by carbon)from the euphotic zone was estimated in the study region,which ranged from 4.14–14.7 mmol/(m2·d),withanaverageof8.21mmol/(m2·d),occupying35%oftheprimeproductivity in the study area.The results of this study can provide new information for better understanding the carbon biogeochemical cycle within the continental slope of the ECS. 相似文献