Diurnal Variations of Hydrochemistry in a Travertine-depositing Stream at Baishuitai, Yunnan, SW China

Diurnal variations of hydrochemistry were monitored at a spring and two pools in a travertine-depositing stream at Baishuitai, Yunnan, SW China. Water temperature, pH and specific conductivity were measured in intervals of 5 and 30 min for periods of 1 to 2 days. From these data the concentrations of Ca²⁺, HCO₃⁻, calcite saturation index, and CO₂ partial pressure were derived. The measurements in the spring of the stream did not show any diurnal variations in the chemical composition of the water. Diurnal variations, however, were observed in the water of the two travertine pools downstream. In one of them, a rise in temperature (thus more CO₂ degassing) during day time and consumption of CO₂ due to photosynthesis of submerged aquatic plants accelerated deposition of calcite, whereas in the other pool, where aquatic plants flourished and grew out of the water (so photosynthesis was taking place in the atmosphere), the authors suggest that temperature-dependent root respiration underwater took place, which dominated until noon. Consequently, due to the release of CO₂ by the root respiration into water, which dominated CO₂ production by degassing induced by temperature increase, the increased dissolution of calcite was observed. This is the first time anywhere at least in China that the effect of root respiration on diurnal hydrochemical variations has been observed. The finding has implications for sampling strategy within travertine-depositing streams and other similar environments with stagnant water bodies such as estuaries, lakes, reservoirs, pools and wetlands, where aquatic plants may flourish and grow out of water.     

Research on Practicability and Feasibility for a New-Type Tuned Mass Damper System-TMD

lNTRODUCTIONThe theories and applications of structural contr()l tlcveloped rapidly in the last 20 years. As one of the additiona1 I)asslve control technologY' TMD is used in practice and can suppress the vibration caused by wind or machinery shake (Ayorinde and Warburton, 1980; Den Hartog, l956 ). The TMDsystem has been used in the industrial and civil buildlngs t() rc-duce structural vibration in some European and American ()o[lntries (Ayorinde and Warburton, l980; Warburton. ] f)…     

大尺寸高精度三维控制网技术探讨

空间大尺寸机构的位置和姿态测量是诸多领域中不可或缺的必要环节。而传统的一维测量技术在精度、范围和速度上已经无法满足越来越高的需求,因此必须探索新的测量技术和方法。激光跟踪仪的单站坐标测量精度在局部范围内能够达到几十个微米量级,如果要在大尺度空间内同样实现该坐标测量精度,则需要建立全局的精密三维控制网。为了解算控制点全局坐标以及测站的位置和姿态参数,文中基于边角观测值和坐标转换模型建立了激光跟踪仪三维边角网整体平差模型。平差过程中,为了削弱激光跟踪仪测角误差的影响,建立了合理的角度和距离观测值权矩阵,为高精度距离观测值赋予较大的权值,从而对其进行约束。将该方法应用于宝钢不锈钢冷轧厂生产线的安装检测和轧辊轴线平行度测量,基于激光跟踪仪自由设站理论实现大尺寸精密三维控制网的建立,取得了良好效果。     

航天器精测数据可视化模型U-SAM设计及实现

经纬仪测量设备能够获取卫星及星上仪器设备安装的角度和位置等精测数据,而从测量数据本身不易直观分析出航天器壳体结构和星上设备安装的精度。为此设计了一种基于Unity的航天器精测数据可视化模型——U-SAM。本文在分析目前航天器精测数据可视化存在问题的基础上;重点阐述和论证结合立方镜准直测量原理设计U-SAM可视化模型的方法;并测试了基于U-SAM模型的可视化效果。结果表明,基于该模型对测量数据可视化能够形象、直观、快速地反映测量数据目前具有的或在随后的测量过程中可能出现的误差趋势,从而指导工作人员对设备总装、测量手段等进行不断地调整和优化。该模型能够高效地对测量数据进行诊断,检测测量数据的正确性和有效性为航空航天部门提供技术支持,减轻测量工作强度,提高工作效率。     

阿合奇地震台地倾斜观测与气温变化关系

通过提取地倾斜EW分量资料与气温资料作对比分析,认为EW分量短期变化与气温变化关系明显,但年变幅度变化与气温年变幅度关系不明显,且每次阿合奇地震台周围200 km范围内发生中强地震前,EW分量均出现趋势性的倾斜速率改变或者倾斜方向改变,说明该台地倾斜变化趋势与地震对应关系较为明显.而年变幅度与相位所含信息较为复杂,与地...     

云南白水台钙华景区的水化学动态变化研究

本文采用水化学仪器自动记录、现场测定和取样室内分析等相结合的方法,对云南白水台钙华景区水的物理化学动态变化特征进行了综合研究,结果发现: 随着CaCO3 的沉积,水中的主要离子Ca2+ 和HCO-3 浓度、电导逐渐降低; p H值升高。我们对1号泉进行昼夜观测发现: 5月1号泉的水温呈周期性变化,周期约为28小时,而在9月水温保持恒定。对下游( 12号观测点)的动态观测发现水的p H值与水温呈反相关关系,在对中游( 6号观测点)的早、中、晚观测得到了同样的结果。最终我们得出结论: 1号泉水温变化可能受补给水源水温动态变化、降雨和地热影响;中下游pH值和电导率的变化与碳酸钙的沉积速率、碳酸平衡和藻类作用有关。      

碳酸盐岩岩溶作用对大气CO2 沉降的贡献

精确预测大气CO2 的未来变化对于预测全球气候变化是至关重要的。为此,需要确定大气CO2 的源和汇及其随时间的变化。本文作者利用已发表和未发表的资料对一些实例进行了分析: 首先讨论了碳酸盐岩岩溶作用(包括碳酸盐溶解及再沉积的共同影响)对土壤CO2和径流变化的敏感性;接着利用水化学- 流量方法和碳酸盐岩石片试验方法得出了我国和世界碳酸盐岩地区因碳酸盐岩岩溶作用从大气中吸收的净CO2 总量,即碳酸盐岩岩溶作用对大气CO2 沉降的贡献。它们分别是: 中国每年1800万tC,整个世界岩溶地区1. 1亿tC;最后,文章据DBL理论模型计算得出世界碳酸盐岩地区碳酸盐岩溶解吸收CO2 一项产生的大气CO2 沉降量为每年4. 1亿tC,继而得出全世界碳酸盐岩地区因碳酸盐再沉积而释放CO2 产生的大气CO2 源项为每年3亿tC。      

Effect of coal mine waters of variable pH on springwater quality: A case study

Disruption of coal strata during mining accelerates pyrite oxidation by exposing greater surface areas of the reactive mineral to weathering. Acidic water in a coal mine in the Niangziguan spring watershed is related to this process and is characterized by low pH (min. 2.52) and high sulfate (max. 4100 mg/I), iron (max. 257 mg/I), and hardness (max. 2274.45 mg/I). However, it is possible that the kind of acidic coal mine water is subsequently neutralized because of the dissolution of calcite present in the coal strata. The hydrochemical characters of the alkaline coal mine water produced are high pH (max. 8.18), sulfate (max. 542 mg/I), and hardness (max. 1183.56 mg/I) and lower iron (min. 0.12 mg/I). Experiments were conducted to further understand the mechanism of the formation of both acidic and alkaline waters in the spring watershed coal mines by modeling natural conditions with simplification, and the results of the experiments have shown that they are basically successful. The high sulfate (max. 223.82 mg/I) and hardness (max. 435.53 mg/I) of the Niangziguan springs are related to the influence of the neutralized acid coal mine water as demonstrated by analysis of water temperature, total dissolved solid, Q-mode cluster analysis, and sulfur isotopes. The influence of the neutralized acid coal mine water on the pH and iron in the springs is not obvious because of the neutralization effect of calcite in aquifer, the buffer effect of groundwater, and the precipitation of iron. Some measures to prevent the formation of acid and alkaline coal mine water are presented.     

普定岩溶水-碳循环模拟试验场水体双碳同位素特征(δ13C-Δ14C)与碳足迹

河流输送到海洋的溶解无机碳(DIC)和有机碳(OC)受自然和人为双重因素的影响。了解DIC和OC的年龄、来源和转化,有助于掌握全球碳收支和提高现在以及未来自然和人类对河流碳循环影响的估算精度。本研究以普定岩溶水-碳循环试验场泉(地下水)-池(地表水)耦联系统为研究对象,利用双碳同位素(¹³C- ¹⁴C)方法,结合水生植物生长和传统水文地球化学特征,揭示了地下水-地表水系统中DIC和颗粒有机碳(POC)的来源及其转化机制。研究发现:(1)泉-池系统中DIC和POC的Δ¹⁴C具有相同的变化趋势,泉水中Δ¹⁴C值低于池水中Δ¹⁴C值,反映后者可能有“较年轻”的CO₂的加入;(2)池水水化学和碳同位素变化由土地利用类型和池中水生植物共同控制;(3)池水中颗粒有机碳(POC)浓度明显高于泉水,且其Δ¹⁴C值表现出与沉水植物和DIC的一致性(表观年龄均为3 200900 a),说明池水POC主要源于池中水生植物光合作用利用了碳酸盐风化产生的老碳(DIC),使新形成的有机质在表观年龄上“偏老”;(4)池水水体内源有机碳对水体POC的贡献在75%以上,内源有机碳通量(以C计)在250 t·km^-2·a^-1至660 t·km^-2·a^-1之间,相对于其他土地利用类型,草地对应的地表水系统具有最大的内源有机碳占比和通量,指示了沉水植物控制型浅水水体初级生产对有机碳循环的重要作用。综上,我们认为在岩溶区通过土地利用调整来调控水生植物群落对于增加碳汇具有重要潜力。