Occurrence and distribution of bacteria indicators,chemical tracers and pathogenic vibrios in Singapore coastal waters     

Shin Giek Goh  Stéphane Bayen  David Burger  Barry C. Kelly  Ping Han  Vladan Babovic  Karina Yew-Hoong Gin 《Marine pollution bulletin》2017,114(1):627-634

Water quality in Singapore's coastal area was evaluated with microbial indicators, pathogenic vibrios, chemical tracers and physico-chemical parameters. Sampling sites were grouped into two clusters (coastal sites at (i) northern and (ii) southern part of Singapore). The coastal sites located at northern part of Singapore along the Johor Straits exhibited greater pollution. Principal component analysis revealed that sampling sites at Johor Straits have greater loading on carbamazepine, while turbidity poses greater influence on sampling sites at Singapore Straits. Detection of pathogenic vibrios was also more prominent at Johor Straits than the Singapore Straits. This study examined the spatial variations in Singapore's coastal water quality and provided the baseline information for health risk assessment and future pollution management.  相似文献   

Mesocosm experiments identifying hotspots of groundwater upwelling in a water column by fibre optic distributed temperature sensing          下载免费PDF全文

Amaya Irene Marruedo Arricibita  Stefan Krause  Jesus Gomez‐Velez  David M. Hannah  Jörg Lewandowski 《水文研究》2018,32(2):185-199

Lacustrine groundwater discharge (LGD) can substantially impact ecosystem characteristics and functions. Fibre optic distributed temperature sensing (FO‐DTS) has been successfully used to locate groundwater discharge into lakes and rivers at the sediment–water interface, but locating groundwater discharge would be easier if it could be detected from the more accessible water surface. So far, it is not clear if how and under which conditions the LGD signal propagates through the water column to the water surface–atmosphere interface, and what perturbations and signal losses occur along this pathway. In the present study, LGD was simulated in a mesocosm experiment. Under winter conditions, water with temperatures of 14 to 16 °C was discharged at the bottom of a 10 × 2.8‐m mesocosm. Water within this mesocosm ranged from 4.0 to 7.4 °C. Four layers (20, 40, 60, and 80 cm above the sediment) of the 82 cm deep mesocosm were equipped with FO‐DTS for tracing thermal patterns in the mesocosm. Aims are (a) to test whether the positive buoyancy of relatively warm groundwater imported by LGD into shallow water bodies allows detection of LGD at the lake's water surface–atmosphere interface by FO‐DTS, (b) to analyse the propagation of the temperature signal from the sediment‐water interface through the water column, and (c) to learn more about detectability of the signal under different discharge rates and weather conditions. The experiments supported the benchmarking of scale dependencies and robustness of FO‐DTS applications for measuring upwelling into aquatic environments and revealed that weather conditions can have important impacts on the detection of upwelling at water surface–atmosphere interfaces at larger scales.  相似文献   

Spatio‐temporal tracer variability in the glacier melt end‐member — How does it affect hydrograph separation results?          下载免费PDF全文

Jan Schmieder  Jakob Garvelmann  Thomas Marke  Ulrich Strasser 《水文研究》2018,32(12):1828-1843

Geochemical and isotopic tracers were often used in mixing models to estimate glacier melt contributions to streamflow, whereas the spatio‐temporal variability in the glacier melt tracer signature and its influence on tracer‐based hydrograph separation results received less attention. We present novel tracer data from a high‐elevation catchment (17 km², glacierized area: 34%) in the Oetztal Alps (Austria) and investigated the spatial, as well as the subdaily to monthly tracer variability of supraglacial meltwater and the temporal tracer variability of winter baseflow to infer groundwater dynamics. The streamflow tracer variability during winter baseflow conditions was small, and the glacier melt tracer variation was higher, especially at the end of the ablation period. We applied a three‐component mixing model with electrical conductivity and oxygen‐18. Hydrograph separation (groundwater, glacier melt, and rain) was performed for 6 single glacier melt‐induced days (i.e., 6 events) during the ablation period 2016 (July to September). Median fractions (±uncertainty) of groundwater, glacier melt, and rain for the events were estimated at 49±2%, 35±11%, and 16±11%, respectively. Minimum and maximum glacier melt fractions at the subdaily scale ranged between 2±5% and 76±11%, respectively. A sensitivity analysis showed that the intraseasonal glacier melt tracer variability had a marked effect on the estimated glacier melt contribution during events with large glacier melt fractions of streamflow. Intra‐daily and spatial variation of the glacier melt tracer signature played a negligible role in applying the mixing model. The results of this study (a) show the necessity to apply a multiple sampling approach in order to characterize the glacier melt end‐member and (b) reveal the importance of groundwater and rainfall–runoff dynamics in catchments with a glacial flow regime.  相似文献   

西南某岩溶区地下水系统示踪试验与解析     

张浪  李俊  潘晓东  黄晓荣  彭聪 《中国岩溶》2020,39(1):42-47

以西南某典型岩溶区为例,解析示踪试验在岩溶管道连通性以及获取水文地质参数中的应用。选择落水洞为投放点,分别从落水洞西侧和东侧寻找地下水出露点作为接收点,判别落水洞地下径流的实际去向以及落水洞与接收点之间的水力联系。结合Qtracer2软件对示踪试验成果进行定量解析,确定示踪剂回收率、地下水平均流速、最快流速,估算出岩溶管道结构特征和水文地质参数。结果表明:落水洞与接收点JS01、JS03之间不存在直接水力联系;落水洞与接收点JS02存在水力联系且岩溶管道极为发育,含水介质不均匀,地下水运移路径较为通畅,为典型的紊流流态;落水洞地下径流的主要方向是由西向东,但在丰水期雨量较大期间,接收点JS04能够接收到荧光素钠,说明丰水期水位上涨后两者间会有水力联系,导致部分水量向落水洞西侧排泄。  相似文献   

钛同位素地球化学综述     

赵新苗  唐索寒  李津  朱祥坤  王辉  李志汉  张宏福 《地学前缘》2020,27(3):68-77

随着分析技术的进步,非传统稳定同位素体系在地球化学、天体化学和生物地球化学等研究领域的应用日益广泛。钛(Ti)是一个非常重要的过渡族金属元素,在地球和其他类地球行星中广泛存在。但是由于Ti是一种难熔的、流体不活动性元素,高温地质过程中Ti同位素分馏很小。人们对Ti同位素体系的地球化学应用的关注相对其他非传统稳定同位非常有限。而近年来,随着化学纯化方案的优化以及双稀释剂方法的改进和仪器质谱性能的提高,Ti同位素组成的高精度测试已经能够实现。天然样品中Ti同位素组成的变化随之得以发现,使得学者们能够利用这一新的稳定同位素体系来解决与高温和低温地球化学相关的问题。很快Ti同位素体系地球化学研究成为当前国际地质学界的前沿研究课题和新的发展方向之一。本文首先在简要介绍Ti元素和Ti同位素体地球化学性质的基础上,介绍了Ti元素化学分离和Ti同位素分析方法。随后笔者总结了已有的不同类型球粒陨石和地球样品的质量相关Ti同位素组成研究结果,对硅酸盐地球的Ti同位素组成做了初步评估。前人对高温地质样品的Ti同位素组成研究初步探明Ti同位素在岩浆演化过程,例如部分熔融和结晶分异等重要地质过程中的分馏行为。笔者在此基础上探讨了结晶分异过程中引起Ti同位素分馏的主要控制因素,指出Ti同位素是潜在的研究岩浆演化过程的新工具。最后笔者探讨了Ti同位素地球化学未来的发展方向,以加速我国在Ti同位素地球化学方面的应用研究。  相似文献   

钾稳定同位素研究综述     

王昆  李伟强  李石磊 《地学前缘》2020,27(3):104-122

钾稳定同位素是重要的非传统稳定同位素体系,也是近年来迅速发展的热门研究课题。对钾同位素研究历史和现状进行综述,具体包括以下内容:(1)总结了钾元素的地球化学和宇宙化学性质,包括钾在主要地质储库(地幔、地壳、海洋)中的丰度及其分配,钾在岩浆演化中的不相容大离子亲石性,常见含钾火成岩/沉积岩矿物以及钾在表生过程中的循环,也包括主要行星物质(球粒陨石、非球粒陨石、火星和灶神星陨石以及月球样品)中钾的含量、赋存状态、主要矿物,钾在太阳星云冷凝、行星积聚以及岩浆海过程中的中等挥发性质;(2)介绍了钾同位素的研究历史,从1922年Dempster利用最早的质谱仪测量钾同位素在自然界的丰度,到Taylor和Urey在1938发表的经典的钾同位素分馏实验,再到Humayun和Clayton在1995年发表的钾同位素领域的经典研究,最后到近几年的进展;(3)介绍了对钾的前处理(离子交换柱法)以及钾同位素的主要测量方法,包括早期热电离质谱仪法(TIMS),二次离子质谱仪法(SIMS)和近十几年以来高速发展的多接收电感耦合等离子体质谱仪法(MC-ICP-MS)及其不同的技术路线;(4)介绍了高精度钾同位素比值在低温地球化学和生物地球化学中的应用,包括钾同位素在地表的风化过程中、海水洋壳的反向风化作用中的分馏及其在示踪全球钾元素循环和洋壳俯冲等过程中的应用;(5)介绍了高精度钾同位素比值在高温地球化学中的应用,包括钾同位素在岩浆分异和矿物结晶过程中的分馏;(6)介绍了高精度钾同位素比值在宇宙化学中的应用,包括在太阳星云冷凝、行星凝聚、月球形成大碰撞、岩浆海、火山喷发去气过程中的分馏作用。  相似文献   

Multimodal water age distributions and the challenge of complex hydrological landscapes     

Nicolas B. Rodriguez  Paolo Benettin  Julian Klaus 《水文研究》2020,34(12):2707-2724

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Transient sediment supply in a high‐altitude Alpine environment evidenced through a 10Be budget of the Etages catchment (French Western Alps)          下载免费PDF全文

Romain Delunel  Peter A. van der Beek  Didier L. Bourlès  Julien Carcaillet  Fritz Schlunegger 《地球表面变化过程与地形》2014,39(7):890-899

Although beryllium‐10 (¹⁰Be) concentrations in stream sediments provide useful synoptic views of catchment‐wide erosion rates, little is known on the relative contributions of different sediment supply mechanisms to the acquisition of their initial signature in the headwaters. Here we address this issue by conducting a ¹⁰Be‐budget of detrital materials that characterize the morphogenetic domains representative of high‐altitude environments of the European Alps. We focus on the Etages catchment, located in the Ecrins‐Pelvoux massif (southeast France), and illustrate how in situ ¹⁰Be concentrations can be used for tracing the origin of the sand fraction from the bedload in the trunk stream. The landscape of the Etages catchment is characterized by a geomorphic transient state, high topographic gradients, and a large variety of modern geomorphic domains ranging from glacial environments to scarcely vegetated alluvial plains. Beryllium‐10 concentrations measured in the Etages catchment vary from ~1 × 10⁴ to 4.5 × 10⁵ atoms per gram quartz, while displaying consistent ¹⁰Be signatures within each representative morphogenetic unit. We show that the basic requirements for inferring catchment‐wide denudation from ¹⁰Be concentration measurements are not satisfied in this small, dynamic catchment. However, the distinct ¹⁰Be signature observed for the geomorphic domains can be used as a tracer. We suggest that a terrestrial cosmogenic nuclide (TCN) budget approach provides a valuable tool for the tracing of material origin in basins where the ‘let nature do the averaging’ principles may be violated. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

湖南祁东清水塘铅锌矿床成矿物质来源同位素示踪   总被引：3，自引：0，他引：3  

路睿  缪柏虎  徐兆文  陆建军  王汝成  左昌虎  屈金宝  赵增霞 《地质学报》2017,91(6):1285-1298

清水塘铅锌矿床位于湖南省祁东县北东部,是一个中型矿床。在详细的野外地质调查基础上,本文通过矿石硫、铅同位素,含矿石英氢、氧同位素和含矿方解石碳、氧同位素等综合研究,探讨清水塘铅锌矿床成矿物质来源和成因。硫同位素研究结果表明,清水塘铅锌矿床中黄铁矿、方铅矿和闪锌矿的硫同位素δ~(34)S介于-7.41‰~2.91‰之间,重晶石的硫同位素δ~(34)S介于11.49‰~12.34‰之间,表明矿石中的硫主要来源于深源岩浆,并受到上部地壳物质的混染。黄铁矿、方铅矿和闪锌矿的Pb同位素~(206)Pb/~(204)Pb介于17.810~18.710之间,~(207)Pb/~(204)Pb介于15.497~15.726之间,~(208)Pb/~(204)Pb介于37.858~38.834之间;其中闪锌矿变化范围略偏大,表明矿石中的铅主要来源于地壳,可能混有少量地幔物质。含矿石英的氢、氧同位素δD_(SMOW)介于-87.4‰~-79.3‰之间,δ~(18)O_(H_2O)介于-8.10‰~0.63‰之间,表明成矿流体以岩浆水为主,晚期有大气降水的混入。含矿方解石的碳、氧同位素δ~(13)C_(VPDB)介于-5.3‰~-4.6‰之间,δ~(18)O_(SMOW)介于12.30‰~13.48‰之间;与地层灰岩的δ~(13)C_(VPDB)(0.9‰~2.6‰),δ~(18)O_(SMOW)(21.86‰~23.39‰)不一致;说明成矿流体中的碳主要来自深源岩浆。以上研究表明,清水塘铅锌矿床的成矿物质主要来自地壳熔融形成的岩浆,混合作用是成矿的主要机制。  相似文献   

桂林甑皮岩洞穴遗址地下水示踪及污染来源分析   总被引：7，自引：7，他引：0  

曾莘茹  姜光辉  郭芳  汤庆佳  刘凡 《中国岩溶》2016,35(3):245-253

桂林甑皮岩遗址周围地带地下水中污染物的种类及来源复杂。为了查明地下水系统的结构特征,分析地下水的污染物运移路径和追溯污染源,采用在线高分辨率示踪技术与人工采样相结合的方法。选取荧光素钠和罗丹明B两种示踪剂,在桂林甑皮岩遗址周围进行了三次示踪试验。根据试验结果分析地下水流场,计算地下水平均流速。结果表明地下水流速在1.6~33.91 m/d,平均值为12.92 m/d。流场内岩溶以溶蚀裂隙为主,且裂隙发育呈网络式,存在西北向东南方向的主径流带,但大型岩溶管道存在的可能性小。三次示踪试验结果均显示,投放点所在的污染源区与遗址周围地下水存在水力联系,因此,遗址附近的居民小区、学校、原砖厂等污染源对遗址下部的地下水存在潜在污染,需更大程度地划分遗址的保护范围。特别是甑皮岩景区化粪池密闭情况较差,严重危害遗址环境,必须对化粪池进行防渗处理。   相似文献