海水入侵引起的某些资源与环境变化——以山东省为例

本文以山东省为例研究了海水入侵与资源和环境的关系。指出,海水入侵是在持续性干旱少雨和过量超采地下水的状态下发生的。海水入侵后引起了资源与环境的显著变化,地下水质恶化,淡水资源趋向匮乏;耕地质量退量退化,耕地生产力降低;植物群落逆向演替;城镇工业规划与布局被迫变化,工业发展受到威胁,人类生产和生活受到限制,地方病发生加剧,人体健康水平和社会文明程度受到一定影响。海水入侵加剧了资源与环境问题。     

水力帷幕防治海水入侵的数值模拟研究

为比较应用于防治海水入侵工程的水力帷幕效果,利用垂向二维非均质流体的对流-弥散模型,运用伽辽金有限元法求解,并用物理实验结果验证其有效性.将模型应用于模拟广西北海市海城区海水入侵过程及水力帷幕防治海水入侵效果,分别计算了超采地下水、抽水、注水和抽-注水情况下咸淡水界面随时间推移过程,并分析咸淡水界面推移与抽、注水流量及抽、注水孔位置之间关系,通过比较得出注水是北海市防治海水入侵较为理想的措施.     

土地利用/土地覆被变化对区域生态环境的影响

土地利用／ 土地覆被变化对区域生态环境的影响是土地利用／ 土地覆被变化研究的重要内容。本文分析了土地利用／ 土地覆被变化对区域气候、土壤、水量和水质的影响。土地利用／ 土地覆被变化通过改变地表发射率、温室气体和痕量气体的含量影响区域气候;土地利用／土地覆被变化影响着能量交换、水交换、侵蚀与堆积、生物循环和作物生产等土壤主要生态过程,不同土地利用方式和土地覆被类型的空间组合影响着土壤养分的迁移规律;土地利用／ 土地覆被变化对水质的影响主要是通过非点源污染途径,许多非点源污染来源都同土地利用／土地覆被变化紧密联系。文中还探讨了由于人类不合理的土地利用造成的土壤侵蚀、土地退化、水资源短缺、海水入侵等生态环境问题。     

海水中微量汞的损失及保存试验

在海洋污染调查中,通常要分析海水中的汞含量,在研究汞在海洋环境中迁移转化规律时,亦要测定它的存在形态。因为海水中汞的含量一般很低,即使有微小的损失,都会影响到分析结果的可靠性,因此,研究海水中汞的     

吸油草对海水中柴油的吸附及其影响因素研究

以柴油污染的海水为对象,研究了吸油草对海水中柴油的吸附、解吸规律,考察了海水盐度、温度和pH三因素对吸附的影响,并根据吸附等温线和吸附热力学的分析探讨了其吸附机理.研究结果表明,吸油草对海水中柴油的吸附及解吸均符合二级反应模式,达到吸附平衡仅需要10～20 min,而达到解吸平衡需要2～3 h,解吸平衡时间是吸附平衡时...     

Ⅱ、渤海湾的悬浮物和沉积物的中子活化分析

一、序言测定海水、海水中的悬浮物以及海底的沉积物中微量元素的浓度,可以为评价海洋的污染情况和研究污染元素的迁移转化规律提供重要依据。悬浮物和沉积物的特点是:(1)基体成分复杂,对于待分析元素易产生干扰,因此要求分析方法分辨率高;(2)海水中悬浮物的总量很少,故要求分析方法取样量要小,而且最好对同一份样品可以做多元素测定;(3)样品中     

外加植物碳源对人工湿地处理海水循环水养殖尾水脱氮性能的影响

针对人工湿地处理海水循环水养殖尾水因碳源不足引起硝态氮去除效果不佳的问题,通过静态释放实验,比较了玉米秸秆、玉米芯以及芒草在海水中的静态释放特性,探究了酸处理和碱处理对玉米芯释放规律的影响,并采用垂直潜流人工湿地系统研究添加玉米芯和玉米芯浸出液对湿地处理海水循环水养殖尾水脱氮效果的影响。结果表明,3种植物碳源都有可观的COD释放量,玉米芯氮素磷素释放量都较小,更适合作为外加碳源;酸处理和碱处理都能提高植物碳源的碳溶出速率,但碱处理的释放速率更稳定,更适合作为预处理方式;添加玉米芯和玉米芯浸出液湿地对硝态氮的去除率分别提高至90.63%和88.56%,表明添加植物碳源能显著提高海水人工湿地的脱氮效果,并证明以植物碳源浸出液替代植物碳源的有效性与可行性。     

湛江东海岛地下水入海排泄量估算及其影响研究

在分析广东省湛江市东海岛的区域水文地质特征及地下水开发利用特点的基础上,构建了地下水入海排泄量估算模型,以估算地下水入海排泄量和携带入海的营养盐量。结果表明,估算得到的2009年东海岛地下水入海排泄总量为133.8×104m3,其中携带入海的营养盐总量为5 157.98kg,地下水的携带入海成为近岸海域陆域营养盐入海排泄的主要途径;研究区位于沿海地带的砂堤砂地潜水分布区以及位于海岸地带的湛江组浅部潜水—微承压水含水层分布区等局部地段,存在地下水入海排泄量的低值区,可能存在海水入侵风险。     

中国沿海地区水资源及生态环境持续利用战略

由于地质和地理条件的特殊性,沿海地区生态环境极其脆弱和敏感。水资源短缺、水环境污染、海水入侵、地面沉降、生态环境退化和海平面上升,已构成我国沿海地区实现可持续发展战略面临的重大资源和环境问题。水资源和生态环境的持续利用,已成为我国沿海地区一项极其重要的战略任务。根据可持续发展理论,通过建立适应水资源持续利用的管理体制、政策和运行机制,采取生态环境可持续保护策略,可完全达到水资源和生态环境的持续利用,并有效实现中国沿海地区资源、环境与经济、社会的有机协调及经济、社会的持续、稳定、健康发展     

镁基-海水法船舶废气脱硫实船实验

建立了一套中试规模的船舶废气脱硫装置,并通过实船实验对比研究了海水法、镁法和镁基-海水法在船舶废气脱硫系统中的应用。研究结果表明,镁法与镁基-海水法的脱硫效率保持在95%左右;海水法开始时脱硫效率能达到90%,40 min内迅速下降至60%;海水法pH下降迅速,而镁法和镁基-海水法pH下降较平缓,且镁基-海水法的pH较镁法更稳定;镁基-海水法喷淋液中碳酸盐总量不减少,不释放CO2。综合分析认为,镁基-海水法是一种具有广阔应用前景的船舶废气脱硫技术。     

Impact of human activities on coastal groundwater pollution in the Yang-Dai River plain,northern China

Environmental Science and Pollution Research - Overexploitation of groundwater has resulted in seawater intrusion in many semiarid and arid coastal areas. This study illustrates the origin of...     

Influence of seaward boundary condition on contaminant transport in unconfined coastal aquifers.

Contaminant transport in coastal aquifers is complicated partly due to the conditions at the seaward boundary including seawater intrusion and tidal variations of sea level. Their inclusion in modelling this system will be computationally expensive. Therefore, it will be instructive to investigate the consequence of simplifying the seaward boundary condition by neglecting the seawater density and tidal variations in numerical predictions of contaminant transport in this zone. This paper presents a comparison of numerical predictions for a simplified seaward boundary condition with experimental results for a corresponding realistic one including a saltwater interface and tidal variations. Different densities for contaminants are considered. The comparison suggests that the neglect of the seawater intrusion and tidal variations does not affect noticeably the overall migration rate of the plume before it reaches the saltwater interface. However, numerical prediction shows that a more dense contaminant travels further seaward and part of the solute mass exits under the sea if the seawater density is not included. This is not consistent with the experimental result, which shows that the contaminant travels upwards to the shoreline along the saltwater interface. Neglect of seawater density, therefore, will result in an underestimation of the exit rate of solute mass around the coastline and fictitious migration paths under the seabed. For a less dense contaminant, neglect of seawater density has little effect on numerical prediction of migration paths.     

The regular pattern and underlying mechanisms of seawater intrusion in the Modaomen channel in the Pearl River Estuary of China

Environmental Science and Pollution Research - In recent decades, the frequency and severity of inland river seawater intrusion has increased in the Pearl River Estuary (PRE) of China. Based on...     

Assessment of groundwater vulnerability in coastal zone using SI method and GIS: case study of Bouficha aquifer (northeast Tunisia)

Environmental Science and Pollution Research - Nowadays, groundwater is under stress due to contamination, over-exploitation, seawater intrusion, climate change, etc. The groundwater contamination...     

A new technique of seawater intrusion control: development of geochemical cutoff wall

Environmental Science and Pollution Research - The construction of a subsurface dam and/or physical cutoff barriers is one of the most known techniques used to prevent seawater intrusion during...     

Evaluation of seawater intrusion and water quality prediction in Dagu River of North China based on fuzzy analytic hierarchy process exponential smoothing method

Environmental Science and Pollution Research - It is of great significance to evaluate the seawater intrusion degree and predict the change of water quality for coastal groundwater resources. This...     

Estimation and uncertainty analysis of groundwater quality parameters in a coastal aquifer under seawater intrusion: a comparative study of deep learning and classic machine learning methods

Environmental Science and Pollution Research - Excessive withdrawal of groundwater for agricultural irrigation can cause seawater intrusion into coastal aquifers. Such a case will in turn results...     

Seawater intrusion vulnerability in the coastal aquifers of southern India—an appraisal of the GALDIT model,parameters’ sensitivity,and hydrochemical indicators

An appraisal of seawater intrusion into the coastal aquifers is one of the major issues for groundwater resource management. The GALDIT model applies to the analysis of multiple parameters using systematic GIS techniques for mapping and assessment of seawater intrusion vulnerability. It demarcates the mapping of potential vulnerability that shows a higher vulnerability to seawater intrusion in various parts of the coast and the estimated vulnerability index value of 7.50 and 9.64. An area of 33.0 km² spread in the low-lying coastal area comprising estuaries, salt marshes, and saltpans shows the high vulnerability condition with an estimated vulnerability value of 6.42–7.50. An area of 73.20 km² spread over coastal and alluvial plains experiences moderate vulnerability (temporal salinity in the groundwater sources) with an estimated vulnerability index value of 5.46–6.42. Aquifers underlying coastal uplands (hard rock formations) and some parts of accretionary beaches (2.05 km²) are relatively protected fresh groundwater sources, wherein the estimated vulnerability index is 4.55–5.46. The vulnerability mapping of the GALDIT model using hydrochemical analysis of primary groundwater parameters such as TDS, Cl^?, HCO₃, and Cl^?/HCO₃ ratio is validated. Higher concentration of TDS (2637–4162 mg/l) and Cl^? (1268–2347 mg/l) is taken for the areas falling under higher vulnerability to seawater intrusion, especially in the placer mining sites and coastal areas facing erosion. Similarly, the groundwater sources of the low-lying areas including estuaries, salt marshes, saltpans, and backwater were noted to have higher values of Cl^?/HCO₃ with a rationality of 9.87–12.18. Hydrological facies shows the highest concentration of NaCl in the groundwater sources within the proximity of eroded beaches, saltwater bodies, and sand mining areas. A hydrochemical facies evolution (HFE) diagram represents the hydrochemical facies of groundwater elements that shows an intrusion of seawater into the coastal aquifers underlying the very high vulnerable zones. Higher bicarbonate concentration (233–318 mg/l) is noticed in the upland areas and some parts of dunes and accreted beaches, sandy coasts, and uplands. Vulnerability analysis reveals that those areas near saltwater bodies and eroding coasts are prone to lateral and vertical diffusion of saltwater. The geodatabase developed through such modeling studies can help in planning and developing activities for sustainable groundwater resource management in coastal areas.