咸淡水界面位置确定的综合方法(TEcG)及其应用     

束龙仓  王明昭  张惠潼  张含明  张乃鹏  孙影  孙超  袁鹏杰 《吉林大学学报(地球科学版)》2019,49(6):1706-1713

准确确定咸淡水界面位置是评价咸水入侵范围的前提。对于咸淡水界面位置的确定,传统研究以水化学法和物探法为主。为克服单一使用传统方法造成的人力、物力和财力的大量浪费,以莱州湾西南岸广饶县小清河以南咸水入侵区为研究对象,在综合分析研究区地下水开采现状、水化学监测结果的基础上,选择3个典型断面,采用水化学法中的野外现场电导率法,快速判断咸淡水界面大致位置（某两眼监测井之间）;再在一咸一淡的两眼监测井之间,采用高密度电阻率法快速、准确地确定咸淡水界面的空间分布。结果表明：该地区的地下水电导率若大于1.61 mS/cm,即可认为此处受到咸水入侵;咸淡水界面位置的视电阻率特征值为11~13 Ω·m,咸淡水界面附近咸水体呈舌状入侵并主要发生在地表以下13 m内的浅层地下水中。  相似文献   

Short-term temporal variations in iron concentration and speciation in a canal during a summer algal bloom     

Takashi Nagai  Akio Imai  Kazuo Matsushige  Kunihiko Yokoi  Takehiko Fukushima 《Aquatic Sciences - Research Across Boundaries》2008,70(4):388-396

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北太平洋冬季SST、风场及环流对淡水强迫的响应     

周舒岚  林霄沛  张进乐 《中国海洋大学学报(自然科学版)》2012,42(5):14-19

通过海气耦合模式CCSM3(The Community Climate System Model version 3),研究在北大西洋高纬度淡水强迫下,北太平洋冬季的海表温度SST、风场及流场的响应及其区域性差异。结果表明:淡水的注入使北太平洋整体变冷,但有部分区域异常增暖;在太平洋东部赤道两侧,SST的变化出现北负南正的偶极子型分布。阿留申低压北移的同时中纬度西风减弱,热带附近东北信风增强。黑潮和南赤道流减弱,北太平洋副热带逆流和北赤道流增强,日本海被南向流控制。风场及流场的改变共同导致了北太平洋SST异常出现复杂的空间差异:北太平洋中高纬度SST的降温主要由大气过程决定,海洋动力过程主要影响黑潮、日本海及副热带逆流区域的SST,太平洋热带地区SST异常由大气与海洋共同主导。  相似文献   

Water temperature interacts with the insecticide imidacloprid to alter acute lethal and sublethal toxicity to mayfly larvae     

《新西兰海洋与淡水研究杂志》2012,46(1):115-130

ABSTRACT

Increased temperatures and exposure to agricultural insecticides are increasingly threatening freshwater ecosystems worldwide. However, their combined effects are still poorly understood. We investigated the individual and interactive effects of water temperature and imidacloprid, the most widely used neonicotinoid insecticide, on larvae of two New Zealand mayflies, Deleatidium spp. and Coloburiscus humeralis. Ninety-six-hour bioassays with imidacloprid were performed at 9, 12, 15, 18, 21 and 24°C, in a full-factorial design. Mayfly survivorship and sub-lethal responses of impairment and moulting were recorded. We documented synergistically increased mayfly mortality and immobility with exposure to imidacloprid at higher temperatures, implying temperature-enhanced toxicity of imidacloprid. Survivorship of both mayflies was synergistically reduced by the combination of imidacloprid exposure and increasing temperatures. The same interaction also affected mobility of C. humeralis and moulting frequency of Deleatidium. Our findings suggest that developing a more thorough understanding of temperature-contaminant interactions may be important to allow better protection of aquatic ecosystems.  相似文献   

低径流量条件下海平面上升对长江口淡水资源的影响   总被引：3，自引：0，他引：3  

裘诚  朱建荣 《气候变化研究进展》2015,11(4):245-255

基于长江口水动力及盐水入侵三维数值模式ECOM-si,统筹考虑气候变化导致流域极端低径流量的前提下,研究在未来（2030、2050和2100年）海平面上升过程中,长江口淡水资源分布及总量变化过程,探讨河口三大重要水库取水活动对海平面上升的响应,对防范未来可能出现的盐水入侵危害具有重要作用,也为长江口水源地建设与水库取水调度提供理论依据和技术支持。1999年冬季、2006年秋季和2011年春季期间长江径流量均为自1980年以来的同期最低,且长江口均发生了极为严重、影响巨大的盐水入侵,考虑到径流量的季节变化特点,选取上述3个时期的径流量作为上游边界条件。结果表明,长江口淡水资源在1999年冬季径流量条件下随海平面上升而减少,至2100年大、小潮期间淡水总量相比于2012年分别减少42%和41%,水库最长不宜取水天数增加70%以上;在2006年秋季径流量条件下,淡水资源随海平面上升而减少,但在海平面上升至2050年情况下,河道水位抬升使进入北支的径流量增加,削弱盐水倒灌,水库最长不宜取水天数减少40%~50%;在2011年春季径流量条件下,淡水资源在海平面上升至2100年后大、小潮期间分别减少43%和20%,水库最长不宜取水天数增加1~3 d。  相似文献   

滨海盐碱地区包气带中淡水透镜体维持机理     

赵林  莫惠婷  郑义 《吉林大学学报(地球科学版)》2016,46(1):195-201

大气降水是滨海盐碱地区浅层地下水的重要补给来源。滨海地区浅层地下水多为咸水且埋藏较浅,在不同包气带岩性渗透性差异下,在大气降水入渗补给过程中,一定时间内潜水面以上一定范围内存在淡水分布,即淡水透镜体,它能局部隔离地下咸水对上层土壤和植物的危害,并在一定程度上供给植物吸收利用。采用自制的室内物理模拟装置,通过控制土层结构,模拟了大气降水入渗补给条件下包气带中淡水透镜体的形成与消退过程,探讨了不同土壤类型中淡水透镜体的维持情况;并利用吸水管模拟客土上所种植物根系吸水,研究了不同吸水量条件下土壤中淡水透镜体的变化规律。结果表明:上层中砂、底层粉砂质黏土的双层土体结构中,淡水透镜体的维持性最好,在降水入渗补给条件下,透镜体形成时间在1500 min左右可达最大厚度(约15 cm),若补给源消失,透镜体完全消退需7500 min,能较长时间地阻隔地下咸水;双层土中模拟形成的稳定淡水透镜体在无补给条件下,能够隔离地下咸水的同时亦能为上层植物提供243.5 mL淡水资源。  相似文献   

Characterisation of sea-water intrusion in the Pioneer Valley, Australia using hydrochemistry and three-dimensional numerical modelling     

A. D. Werner  M. R. Gallagher 《Hydrogeology Journal》2006,14(8):1452-1469

Sea-water intrusion is actively contaminating fresh groundwater reserves in the coastal aquifers of the Pioneer Valley, north-eastern Australia. A three-dimensional sea-water intrusion model has been developed using the MODHMS code to explore regional-scale processes and to aid assessment of management strategies for the system. A sea-water intrusion potential map, produced through analyses of the hydrochemistry, hydrology and hydrogeology, offsets model limitations by providing an alternative appraisal of susceptibility. Sea-water intrusion in the Pioneer Valley is not in equilibrium, and a potential exists for further landward shifts in the extent of saline groundwater. The model required consideration of tidal over-height (the additional hydraulic head at the coast produced by the action of tides), with over-height values in the range 0.5–0.9 m giving improved water-table predictions. The effect of the initial water-table condition dominated the sensitivity of the model to changes in the coastal hydraulic boundary condition. Several salination processes are probably occurring in the Pioneer Valley, rather than just simple landward sea-water advancement from “modern” sources of marine salts. The method of vertical discretisation (i.e. model-layer subdivision) was shown to introduce some errors in the prediction of water-table behaviour.  相似文献   

Hydrodynamic convergence of hydropressured and geopressured zones, Central Texas, Gulf of Mexico Basin, USA     

Alan R. Dutton  Jean-Philippe Nicot  Katherine S. Kier 《Hydrogeology Journal》2006,14(6):859-867

Freshwater moving downdip in the Carrizo–Wilcox aquifer, Central Texas, USA, and saltwater and hydrocarbons moving updip from a geopressured zone come together in a groundwater convergence zone, marked by (1) a hydraulic-gradient reversal, (2) “updip” oil fields, and (3) the downdip limit of potable water beyond which there is a marked increase in salinity. Data combined from groundwater-supply and petroleum-extraction industries document the interface between the hydropressured and geopressured zones. The hydraulic-head gradient updip of the convergence zone is 0.001 to 0.002, directed toward the coast; farther downdip it is ?0.02 to ?0.04, directed inland. Salinity increases from <400 mg/L near the outcrop, to ～3,000 mg/L at the downdip limit of potable water, to >100,000 mg/L in the geopressured zone. Upward-directed flow paths probably predominate in the convergence zone. The convergence zone in the study area lies within only 30–50 km of the outcrop because updip extensional faulting offsets permeable aquifer units against low-permeability strata and restricts the downdip flux of recharged water. The major elements of the convergence zone may have been in place since the Miocene development of circulation in the updip coastal aquifer following incision of river valleys and lowering of base level.  相似文献   

The sedimentary coastal basin of Togo: example of a multilayered aquifer still influenced by a palaeo-seawater intrusion   总被引：3，自引：0，他引：3  

Ari Akouvi  Martial Dray  Sophie Violette  Ghislain de Marsily  Gian Maria Zuppi 《Hydrogeology Journal》2008,16(3):419-436

In Togo, the hydrogeology of the sedimentary coastal aquifers along the Gulf of Guinea has been studied for the last three decades to define the recharge processes and the origin and evolution of the salinity. Isotope hydrology and fluid geochemistry suggest that the current recharge of all aquifers, both confined and unconfined, occurs through the crystalline basement and the Plio-Quaternary deposits. Two main groundwater mineralization processes are observed: the first one, in recharge areas, is due to farming, village and city life and concerns unconfined aquifers (crystalline basement, Continental Terminal and Quaternary sediments); the second one is a mixing process between recent freshwater and fossil saline water still present in the deep confined aquifers inland, several kilometers away from the coast. Brackish water was trapped in low-permeability lenses of confined aquifers (Eo-Palaeocene and Maastrichtian) during the Quaternary, in periods of low recharge, notably during the last glacial maximum (LGM), and has not yet been flushed out. Hydrodynamic simulations indicate that, at that time, the aquifers experienced a maximum seawater intrusion as far as 20–22 km inland, depending on the palaeo-recharge value at the outcrops.  相似文献   

The Beaufort Gyre variation and its impacts on the Canada Basin in 2003–2012   总被引：1，自引：1，他引：0  

钟文理  赵进平  史久新  曹勇 《海洋学报(英文版)》2015,34(7):19-31

The Beaufort Gyre (BG) was spun up in the last decade which is an important factor in regulating the variation of the upper ocean. The heat content and freshwater content of the upper ocean increased g...  相似文献