Simulation of chloride migration rates in Paleo Pennar Delta Region, Coastal Andhra Pradesh, India   总被引：1，自引：0，他引：1  

M. V. R. Chowdary  I. Radhakrishna 《Environmental Geology》1998,36(1-2):109-117

 Quaternary alluvial aquifers in the paleo Pennar delta region of Andhra Pradesh (Long. 80°0′ and 80°12′; Lat. 14°40′ and 14°20′) constitute an important coastal strip, with potential fresh groundwater resources and several well fields in operation. The lineament patterns and traces of paleo channels provide basic information on the configuration and boundaries of paleo delta and the possible neotectonic movements in the region. The paleo delta region is essentially characterized by freshwater aquifer systems at the near-surface depths, (up to 50 m from ground level) with transmissivity values in the system ranging from 1200 to 2500 m²/day. This groundwater system has been subjected to heavy draft situation over the last two decades, parlicularly near the outer rim of the delta where an unlined brackish-water canal runs parallel to the coast imparting chloride contamination to the adjoining fresh aquifers. A two-dimensional solute transport model solution was applied to assess chloride migration rates inland under different hydraulic stresses, combining finite difference solution of flow equation and the method of characteristic solution of solute transport equation. Groundwater flow and chloride migration patterns/rates were obtained for different simulated stress events in the delta system, and measures required to protect the freshwater resources ara outlined. Received: 2 January 1997 · Accepted: 4 November 1997  相似文献   

Simulations of accidental coal immersion     

Jaffrennou C  Giamarchi P  Cabon JY  Stephan L  Burel-Deschamps L  Bautin F  Thomas A  Dumont J  Le Floch S 《Marine pollution bulletin》2007,54(12):1932-1939

Coal is currently becoming an increasingly interesting fossil energy resource and that is the reason why its maritime transport, and hence the risk of collier accidents, increase. In this work, the environmental impact of an accidental coal immersion at sea is studied: the physicochemical effects are estimated using innovative experimental setups – a laboratory seawater canal called “polludrome” is used to evaluate the behaviour of coal particles submitted to a seawater flow, and a specifically designed tub is used to study the physicochemical consequences induced when coal is introduced into continuously renewed seawater. When coal is introduced into seawater, the most easily visible consequences are physical: fine coal particles reduce the daylight penetration up to 100% and move along with the flow, and coal chunks accumulate on the floor. Chemical effects are also measured: humic matters are dissolved from coal into seawater (up to 2 mg L⁻¹), but no release of polycyclic aromatic hydrocarbons is evidenced. Some inorganic compounds are dissolved, among which manganese, whose concentrations can reach 1 μg L⁻¹. Fortunately, the results show that the environmental impact of this type of accident would remain limited.  相似文献   

标准海水研究现状及其应用     

赵卓英  田孟安  孙浩  胡波 《海洋通报》2011,30(3):283-286

标准海水作为海水盐度量值的标准物质,广泛用于检定和校准海水盐度测量仪器和装置.主要介绍两种标准物质-中国-级标准海水和中国系列标准海水,系统介绍我国现阶段标准海水的制备,封装工艺,保存方法,并阐述其在使用过程中的注意事项.  相似文献   

Groundwater ages in coastal aquifers     

《Advances in water resources》2013

The interpretation of groundwater ages in coastal aquifers requires an improved understanding of relationships between age distributions and the processes accompanying dispersive, density-dependent flow and transport. This study uses numerical modeling to examine the influence of mixing and a selection of other hydrogeological factors on steady-state age distributions in coastal aquifers. Three methods of age estimation are compared: the piston flow age, the direct age, and the tracer-based age. These are applied to various forms of the Henry problem, as well as to three variants of a larger, hypothetical coastal aquifer. Circulation of water within the seawater wedge results in markedly higher ages in the transition zone than in the underlying saltwater or overlying freshwater. Piston flow ages show a sharp increase where the freshwater and saltwater systems meet, whereas direct- and tracer-based simulations result in a smoother age distribution, as expected. Greater degrees of mixing result in larger differences between piston flow and direct or tracer-based ages, and bring about lower ages in the saltwater wedge. Tracer-based ages are preferred over direct- and piston flow ages for comparison with field data, especially in cases with wide transition zones. Despite the relatively simple conditions used for the simulations, complex age distributions with depth were obtained. Hence, the assessment of ages in field cases will be difficult, particularly where accurate ages in the transition zone are sought.  相似文献   

Activity concentration of caesium-137 in seawater and plankton of the Pomeranian Bay (the Southern Baltic Sea) before and after flood in 1997     

Knapinska-Skiba D  Bojanowski R  Piekoś R 《Marine pollution bulletin》2003,46(12):1558-1562

Activity coefficients of 137Cs determined during culminating flood waters in August 1997 in the estuary of the Oder River, discharging to the Pomeranian Bay as well as in the coastal and open-seawaters of the Bay, did not show enhanced levels of the nuclide as compared to those measured before the flood. It is thus concluded that the flood did not contribute to releasing the nuclide from eroded soil particles. The bioconcentration factors of 137Cs in the riverine plankton has been found to be one to two orders of magnitude higher than those determined in the Pomeranian Bay plankton.  相似文献   

深海溶解态锰和铁的原位分析技术研究进展     

潘安阳  杨群慧  周怀阳  王虎  季福武 《地球科学进展》2013,28(4):420-428

溶解态的锰和铁是海洋中重要的生物营养元素,也是探查海底热液活动及其演化的重要示踪剂.由于海底热液活动研究的迫切需求,以及AUV,ROV和HOV等水下运载支撑平台的迅速发展,20世纪80年代以来深海溶解态锰铁原位分析技术得到了快速发展.早期研发的Scanner和SUAVE,可对热液羽流中高含量的锰铁元素实现联合测定,但存在元素之间相互干扰等问题,因此针对锰、铁元素单独测量的原位分析仪应运而生.锰原位分析仪中,ZAPS虽然具有较低的检测限,但是无法在深海高压环境下进行原位校正;GAMOS系列具有原位校正功能,且能耗较低,可长期运行,但是检测限偏高,因此只能应用于热液环境中含量相对高的锰监测.铁原位分析仪中,改进的ALCHIMIST可实现热液喷口异常高含量铁和正常海域水体中低含量铁的检测,但由于能耗较高而难以应用于长期观测中;低能耗的Fe-Osmo-Analyzer和CHEMINI则在长期运行方面有着明显的优势.随着AUV/ROV/HOV等水下移动平台应用的日渐广泛以及海底观测网技术的迅速发展,发展原位分析仪进行长期的自主观测将成为一种必然趋势.  相似文献   

Temporal and spatial trends of total petroleum hydrocarbons in the seawater of Bohai Bay, China from 1996 to 2005     

Ye Li  Shitao Peng  Lena Q. Ma 《Marine pollution bulletin》2010,60(2):238-243

The temporal and spatial distribution of total petroleum hydrocarbons (TPH) in the seawater of Tianjin Bohai Bay during 1996-2005 was investigated for the first time. TPH concentrations in 480 seawater samples collected from 16 stations during a 10-year span were quantified by ultra-violet fluorescence spectroscopy. Petroleum hydrocarbons were ubiquitous in the seawater, and their concentrations were highly variable, ranging from 23.7 to 508 μg L⁻¹. TPH concentrations in the seawater varied with seasons, showing a decreasing order of winter > spring > summer. Over the 10-year period, TPH at all stations steadily decreased. The highest values obtained were at stations near the port areas and Dagu outfall where shipping activities and land-based waste water discharges were the major sources of pollution. Our results provided the background information on the extent of TPH contamination in the seawater and highlighted the need to further control TPH pollution in Tianjin Bohai Bay.  相似文献   

A study of marine pollution caused by the release of metals into seawater following acid spills     

Jean-Yves Cabon  Stephane Le Floch 《Marine pollution bulletin》2010,60(7):998-1004

This study examined the potential metal pollution induced by the accidental spill of different acids into seawater. The acids sink to the bottom according to their densities and subsequently react with marine sediments. The acids selected for this study were acetic, hydrochloric, nitric, sulfuric, and phosphoric acids; the metallic elements selected were Cr, Cu, Fe, Mn, Pb and Zn. The sediment was collected in Brest Harbour. The percentages of metals released from this sediment in the presence of various concentrations of acids in seawater were important; concentrations of approximately 7 mg L⁻¹ for Mn and 60 mg L⁻¹ for Zn were observed under our experimental conditions. We also examined the rate of release of these metals from the sediment into the seawater in the presence of the different acids and under different experimental conditions. We found that most of the metallic elements were released from the sediments into the seawater during the first fifteen minutes of exposure. After this time, a high degree of pollution was induced if acids leached into seawater were not rapidly diluted.  相似文献   

Hebei Spirit oil spill monitored on site by fluorometric detection of residual oil in coastal waters off Taean, Korea     

Moonkoo Kim  Sang Hee Hong  Hyun-Woo Choi  Jongho Won 《Marine pollution bulletin》2010,60(3):383-7488

The spatiotemporal distributions of dissolved and/or dispersed oil in seawater and pore water were monitored on site by fluorometric detection method after the Hebei Spirit oil spill. The oil concentrations in intertidal seawater, 15 days after the spill, were as high as 16,600 μg/L and appeared to decrease below the Korean marine water quality standard of 10 μg/L at most sites 10 months after the spill. Fluorometric detection of oil in pore water was introduced to eliminate the effects of grain size for the quantification of oil in sediments and to better explain spatial and temporal distribution of oil pollution at sandy beaches. The fluorescence detection method was compared with the conventional laboratory technique of total petroleum hydrocarbon analysis using gas chromatography. The method of fluorescence detection of oil was capable of generating results much faster and more cost-effectively than the traditional GC technique.  相似文献   

Risk Assessment of Aquifer Salinization in a Large‐Scale Coastal Irrigation Scheme,Italy          下载免费PDF全文

Daniele Zaccaria  Giuseppe Passarella  Daniela D'Agostino  Raffaele Giordano  Samuel Sandoval Solis 《洁净——土壤、空气、水》2016,44(4):371-382

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