共查询到19条相似文献，搜索用时 125 毫秒
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河口滨海区的水体是由组成和性质显著不同的河水和海水混合而成的。在河口区河水和海水的混合作用是复杂的动力学过程。在这一过程中还伴随着其他化学过程、物理化学过程和地质过程。诸如由于水质条件的剧变所引起的难溶物的沉淀作用,胶体和悬浮物的聚沉作用,各种固相与溶解成份之间的交换吸附与沉积作用以及气体交换作用等。因此,河口区混合水体所含物质的组成不仅与河水和海水的化学组成以及江河流量、涌入河口的海水量、河口的地形地貌、沿岸的地质、潮汐过程和气象等外界环境条件有关,也与伴随着混合过程而产生的许多复杂的化学、物理化学过程密切相关。这些过程尤其对混合水体中的微量元素的迁移及溶解气体的分布变化有显著的影响。 相似文献
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河水与海水混合过程中Eh-pH的变化特征及影响因素 总被引：1，自引：0，他引：1
河口是河水和海水混合地带,河口地区每时每刻都在发生复杂的物理、化学、生物作用,该过程中水体Eh、pH参数的变化直接关系到氧化还原元素的行为以及重金属、有机污染物的迁移、转化和清除。本研究采集了长江河水、东海陆架海水,设置了盐度为5、12.5、25的3组混合实验,模拟长江河口水体混合过程,实时测定混合过程中水体Eh、pH变化,分析其影响因素。结果表明:混合水体为弱碱性-强氧化环境,pH值变化范围为7.83~8.22,pH值总体上呈现下降的趋势;Eh值变化范围为503.7~579.7 mV,在混合开始的1 h内迅速升高,随后迅速下降并逐渐趋于稳定。河水和海水混合过程中Eh、pH的变化主要受机械混合和氧化还原反应控制,机械混合导致两类水体Eh、pH快速中和,以Fe2+为主的氧化反应消耗了水体中的O2和OH-,使得混合水体中的Eh、pH呈现下降趋势,并逐渐趋于稳定。 相似文献
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滨海潜水含水层的海水入侵过程会受到潮汐波动的影响。本文基于OpenGeoSys科学模拟软件,以动态潮汐边界作为海相边界,建立斜坡海滩潜水含水层海水入侵的二维剖面数值模型,探讨了潜水含水层水位波动及盐度运移规律,突破了传统海水入侵数值模拟过程中忽略潮汐影响的局限性。结果表明:潮汐作用改变了传统海水入侵模型的盐度分布规律及淡水排放通道;在定流量内陆边界条件下,潮汐作用会缩短盐水楔在淡水中的扩散距离,减缓了海水入侵的程度。本文有效地解决了数值模拟时考虑复杂海相边界时遇到的问题,通过数值模拟进一步揭示了潮汐波动影响下的海水入侵机理。本文的研究成果为合理优化开采地下淡水资源、定量评价与防治海水入侵提供科学的理论依据。 相似文献
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渤海莱州湾南岸，是我国海水入侵灾害最严重的岸段。依据入侵物源可将广义海水入侵划分为两种基本类型：来源于现代海水的狭义海水入侵和物源于浅层第四纪沉积层中古海水（包括一般地下咸水及地下卤水）的地下咸水入侵。它们的成因、机理和危害差异明显；地下卤水入侵是一种特殊类型，造灾程度最高。海岸地貌和第四纪水文地质环境，是控制海水入侵类型区划的主导因素。莱州湾南岸不同岸段海岸环境差异，形成了海水入侵区、地下咸水入侵区和海、咸水混合入侵区３种类型区，可具体区划为：莱州市北部海岸海水入侵区，胶莱河－沙河河口平源海、咸水混合入侵区，昌邑北部潍河河口平原海、咸水混合入侵区，寿光北部平原地下咸水入侵区等４个区。类型区划分将有助于海水入侵灾害防治工程。 相似文献
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基岩海岸海水入侵特征及对策——以长岛县南北长山岛为例 总被引：6，自引：0，他引：6
山东省长岛县南、北长山岛地下海水入侵于20世纪70年代，至90年代有明显扩大。海水入侵存在海湾层状况沉积体孔隙式层状入侵、岩岸裂隙式脉状入侵和层状基岩层隙式面状入侵3种基本形式，造成海水入侵不断加剧的原因一方面受大气降水的明显影响，另一方面由于当地经济与社会发展带来的地下淡水过量开采引起，形成了地下水质恶化与城镇和人口稠密区、机井密集区相对应的社会-地质灾害空间组合。防止海水入侵、切实保护地下淡水资源，首先应采取重点地段上实施拦蓄结合的地下水工程，也可以借用天然形成的糜棱岩带作为拦蓄工程基础，以节约资金投入；其次是减少地表径流与地表蒸发，扩大地下淡水量；以及采取以减少地下水资源开发量为目标的开源节流等方面的措施。 相似文献
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莱州湾南岸海水入侵类型及其分区 总被引：6，自引：0，他引：6
渤海莱州湾南岸，是我国海水入侵灾害最严重的岸段。依据入侵物源可将广义海水侵划分为两种基本类型：来源于现代海水的狭义海水入侵和物源于浅层第四沉积层中古海水的地下咸水入侵，它们的成因，机理和危害差异明显；地下卤水入侵是一种特殊类型，造灾程度最高。海岸地貌和第四纪水文地质环境，是控制海水入侵类型区划的主导因素。莱州湾南岸不同岸段海岸环境差异，形成了海水入侵区，地下咸水入侵区和海、咸水混合入侵区３种类型区 相似文献
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随着全球气候变暖,风暴潮在沿海地区的频率和强度均可能增长,由此引发的海水垂向入侵可能会造成大面积的含水层淡水咸化。同时,由人类活动引起的沿海虾塘咸水养殖规模日益增长,由此引发的咸水垂向入侵可能会导致沿海地区地下水水质及生态环境的恶化。虽然已有一部分学者在海水(咸水)垂向入侵的研究中取得了成果,但由于海水(咸水)垂向入侵过程复杂,其对地下水咸化及恢复规律依然有待深入研究。文章阐述了海水垂向入侵的危害及前人的研究办法,总结了他们的研究成果并得出了海水垂向入侵的影响因子,指出了洪水和养殖活动对沿海地区含水层的威胁。得出的结果如下:研究海水垂向入侵常用的方法包括室内试验和数值模拟;海水垂向入侵主要与地形地貌、含水层性质和水文气象条件有关;虾塘养殖等人类活动可能会成为垂向咸水入侵的潜在来源。建议未来在海水垂向入侵研究中将多种现场观测实验方法结合起来。数值模拟应注重与现场观测实验数据相互验证,模型简化的方式有必要仔细考虑。虾塘养殖等人类活动可能造成的垂向咸水入侵问题应更多地受到关注。 相似文献
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桩海地区下古生界古潜山碳酸盐岩孔隙特征与空间组合规律 总被引：1，自引：0，他引：1
基于桩海地区下古生界碳酸盐岩古潜山储层的孔隙特征,分析了研究区不同潜山区块有效孔隙的空间组合特征,探讨了影响研究区下古生界孔隙类型及储层在空间上的组合特征的主控因素。下古生界碳酸盐岩古潜山以裂缝-扩溶缝-溶蚀孔洞为主,原生孔隙基本消失,具有储集意义的主要为次生孔隙。储层在空间上的组合形式主要包括非常发育的潜山内幕储层,且与风化壳储层不具有统一油水界面,深部溶蚀特征明显;太古界变质岩与下古生界碳酸盐岩之间往往具有统一的油水界面;许多下古生界古潜山带具有"上缝下洞"的储集空间特征等。孔隙的次生性及多样化的空间组合形式导致不同潜山区块储集能力的明显差异。多级不整合面古岩溶作用形成相时早期的溶蚀孔隙和潜山内幕储层;深埋藏溶蚀作用对碳酸盐岩先成孔隙的溶蚀改造和太古界与下古生界之间统一油水界面的形成具重要影响;新构造运动和埋藏期溶蚀作用相结合可合理解释研究区下古生界古潜山带"上缝下洞"的储集空间组合形式。 相似文献
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海水和淡水之间的显著电性差异使得直流电阻率法可用于识别和监测海水入侵。洋戴河平原不同海水入侵程度含水层,其电阻率呈现出显著分异,一般规律为:严重入侵(5Ω·m),轻度入侵(5～13Ω·m),未入侵(13～150Ω·m)。结合水文地质钻孔资料,依靠含水层电阻率分布识别海水入侵。结果表明,洋戴河平原部分地区海水入侵进程具有明显的季节效应,由于农灌开采地下水导致6月海水入侵程度较为严重,3、11月海水入侵程度相对较弱。研究区滨海浅层地下咸水(微咸水)区主要分布在河道两侧,并向周围抽水灌溉区发展,其主要来源是海水沿河床入侵后形成的混合咸水以及灌溉回归水。现有的措施已经对海水入侵发展起到了一定的减缓作用,但仍需加强典型地段的防治。 相似文献
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The uncertainty and sensitivity of predicted positions and thicknesses of seawater-freshwater mixing zones with respect to uncertainties of saturated hydraulic conductivity, porosity, molecular diffusivity, longitudinal and transverse dispersivities were investigated in both head-control and flux-control inland boundary systems. It shows that uncertainties and sensitivities of predicted results vary in different boundary systems. With the same designed matrix of uncertain factors in simulation experiments, the variance of predicted positions and thickness in the flux-control system is much larger than that predicted in the head-control system. In a head-control system, the most sensitive factors for the predicted position of the mixing zone are inland freshwater head and transverse dispersivity. However, the predicted position of the mixing zone is more sensitive to saturated hydraulic conductivity in a flux-control system. In a head-control system, the most sensitive factors for the predicted thickness of the mixing zone include transverse dispersivity, molecular diffusivity, porosity, and longitudinal dispersivity, but the predicted thickness is more sensitive to the saturated hydraulic conductivity in a flux-control system. These findings improve our understandings for the development of seawater?freshwater mixing zone during seawater intrusion processes, and give technical support for groundwater resource management in coastal aquifers. 相似文献
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《中国海洋工程》2015,(4)
The uncertainty and sensitivity of predicted positions and thicknesses of seawater-freshwater mixing zones with respect to uncertainties of saturated hydraulic conductivity, porosity, molecular diffusivity, longitudinal and transverse dispersivities were investigated in both head-control and flux-control inland boundary systems. It shows that uncertainties and sensitivities of predicted results vary in different boundary systems. With the same designed matrix of uncertain factors in simulation experiments, the variance of predicted positions and thickness in the flux-control system is much larger than that predicted in the head-control system. In a head-control system, the most sensitive factors for the predicted position of the mixing zone are inland freshwater head and transverse dispersivity. However, the predicted position of the mixing zone is more sensitive to saturated hydraulic conductivity in a flux-control system. In a head-control system, the most sensitive factors for the predicted thickness of the mixing zone include transverse dispersivity, molecular diffusivity, porosity, and longitudinal dispersivity, but the predicted thickness is more sensitive to the saturated hydraulic conductivity in a flux-control system. These findings improve our understandings for the development of seawater?freshwater mixing zone during seawater intrusion processes, and give technical support for groundwater resource management in coastal aquifers. 相似文献
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作者采用水化学演化图（hydrochemical facies evolution diagram,HFE-D）和海水入侵地下水质量指数（GQISWI）对山东威海文登区地下水的化学演化和海水入侵情况进行了分析。Piper图的结果表明文登区从北到南地下水的化学组成分别是Ca-HCO3、Ca-Mg-Cl、Na-Cl。HFE-D表明沿海地区的含水层中海水占主导地位,并且地下淡水补给不足,无明显淡化趋势;内陆地区含水层中的淡水多数处于海水侵入期,有咸化趋势。运用GQISWI、地理信息系统和空间插值法结合,得到了文登区浅层海水入侵现状图。另外,作者考虑渗透系数对离子浓度的影响,运用反距离加权插值算法并结合渗透系数分析了文登区浅层地下水海水入侵程度。结果表明文登沿海地区已经发生了极其严重的海水入侵现象,结合HFED可知咸水有向内陆继续扩散的趋势。研究结果对文登区地下水资源的利用和海水入侵的防治具有重要意义。另外本文是HFE-D和GQISWI在国内文献中的首次应用,为国内其他地区的海水入侵评价提供了参考。 相似文献
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An investigation has been made of available data on the saturation state of seawater with respect to calcium carbonate and its possible significance for scale formation on Ocean Thermal Energy Conversion (OTEC) heat exchangers. Pertinent oceanographic data is lacking at or near potential OTEC sites for the calculation of the degree of saturation of seawater with respect to calcium carbonate. Consequently, only “extrapolated” saturation values can be used. These indicate that near surface seawater is probably supersaturated, with respect to the calcium carbonate phases calcite and aragonite, at all potential OTEC sites. The deep seawater that would be brought to the surface at the potential Atlantic Ocean sites is also likely to be supersaturated with respect to calcium carbonate. The deep seawater at the potential Pacific Ocean sites may be slightly undersaturated.The fact that OTEC heat exchangers will be operating in seawater, which is supersaturated with respect to calcium carbonate, means that if nucleation of calcite or aragonite occurs on the heat exchanger surfaces, significant growth rates of calcium carbonate scale may be expected. The potential for calcium carbonate nucleation is highest at cathodic metal surface locations, which are produced as the result of aluminum corrosion in seawater. Consequently, corrosion and scale formation may be closely related. What the possible effects of biofouling may be on this process are not known. 相似文献
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James R. Hein Ann E. Gibbs David A. Clague Michael Torresan 《Marine Georesources & Geotechnology》2013,31(2):177-203
This is the first article to describe mineralization of midplate submarine rift zones and hydrothermal manganese oxide mineralization of midplate volcanic edifices. Hydrothermal Mn oxides were recovered from submarine extensions of two Hawaiian rift zones, along Haleakala and Puna Ridges. These Mn oxides form two types of deposits, metallic stratiform layers in volcaniclastic rocks and cement for clastic rocks; both deposit types are composed of todorokite and bimessite. Thin Fe‐Mn crusts that coat some rocks formed by a combination of hydrogenetic and hydrothermal processes and are composed of δ‐MnO2. The stratiform layers have high Mn contents (mean 40%) and a large fractionation between Mn and Fe (Fe/Mn = 0.04). Unlike most other hydrothermal Mn oxide deposits, those from Hawaiian rift zones are enriched in the trace metals Zn, Co, Ba, Mo, Sr, V, and especially Ni (mean 0.16%). Metals are derived from three sources: mafic and ultramafic rocks leached by circulating hydrothermal fluids, clastic material (in Mn‐cemented sandstone), and seawater that mixed with the hydrothermal fluids. Mineralization on Haleakala Ridge occurred sometime during the past 200 to 400 ka, when the summit was at a water depth of more than 1,000 m. Hydrothermal circulation was probably driven by heat produced by intrusion of dikces, magma reservoirs, and flow of magma through axial and lateral conduits. The supply of seawater to ridge interiors must be extensive because of their high porosity and permeability. Precipitation of Mn oxide below the seafloor is indicated by its occurrence as cement, growth textures that show mineralizing fluids were introduced from below, and pervasive replacement of original matrix of clastic rocks. 相似文献
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修建海岸水库是满足滨海地区淡水资源的保障的一个重要方式,为了进一步分析海岸水库的建立对滨海含水层的海水入侵的影响,采用SUTRA(saturated-unsaturatedtransport)模型建立具有代表性的二维海岸模型开展定量和定性研究,结果表明:潮汐作用抑制底层盐水楔的入侵,加快海陆物质交换;实例中计算表明建坝后,海岸水库坝体的建立加剧了海水入侵;水库水位在平均海平面以下时,潮汐动力因素占主导,海水入侵严重且随着水位抬高,海水入侵程度基本保持不变,应注意海水入侵的防治;库区水位在平均海平面以上时,海水入侵程度随着库区水位的抬高而减少,可以调节水库水位进行滨海含水层的海水入侵的防控;海岸水库在建设中存在一个控制水位,当水库水位在控制水位以上,库区水体盐度和含水层淡水储量能得到保证;库区高水位时内陆物质运移时间较长,运移区域较广,氮类污染物易在库底含水层堆积,需重视含水层的地下水污染防治。 相似文献