胶州湾洋河口泥质植物沼泽潮滩水化学环境及海水—地下水交换研究

发布时间：2018-02-08 23:06

本文关键词： 泥质潮滩芦苇沼泽湿地水化学特征海水-地下水交换海底地下水排泄(SGD)　出处：《中国地质大学(北京)》2017年硕士论文　论文类型：学位论文

【摘要】：芦苇沼泽湿地是潮间带一种重要的生态系统。研究区位于胶州湾洋河河口泥质潮滩处,采样区分布大量芦苇。采集了光滩区以及芦苇分布区的地下水样,用于对比分析两者水化学特征。在潮滩处布置用于观测地下水位的观测井,分析海水-地下水之间的交换规律,得到如下四个方面的结果:(1)光滩区水化学特征研究。由于蒸发和海潮涨潮的稀释作用,主要离子浓度与至潮沟距离成正比。地表水的混入使得潮滩地下水中HCO3-/Cl-、K+/Cl-、Ca2+/Cl-比值明显偏高;硝酸盐氮的含量偏低,亚硝酸盐氮以及铵态氮含量较高,铵态氮明显大于亚硝酸盐氮,此处反硝化作用较为强烈;沉积物孔隙水中Cu、Cr、Cd的含量符合或者接近三类地下水水质标准。相关性分析显示,Zn、Cr、Pb、Cu可能具有相同来源。(2)光滩与芦苇分布区水化学对比研究。由于两者蒸发作用强弱的不同,除HCO3-和Hg,绝大部分的主要离子和重金属在光滩地下水中的浓度要大于芦苇中的浓度。植物呼吸作用和有机质分解作用导致芦苇区域地下水中的HCO3-较大,同时还说明了芦苇生长对Hg有富集作用;由于沉积物厌氧环境及水生植物生长,无机磷浓度在芦苇区域地下水中大于光滩。在浓度梯度的作用下,主要离子的迁移方向在芦苇区域和光滩区恰好相反,重金属在光滩和芦苇区域的迁移方向基本相同;芦苇区域ORP波动较小,以较强的还原性为主。(3)利用水力梯度法研究海水-地下水交换规律。坡度较缓的泥质潮滩,有利于渗透面发育。高潮时海水更容易渗入潮间带含水层,低潮时含水层中的地下水更容易排泄到海中。利用水力梯度法计算潮沟南北两侧海水-地下水交换量,发现潮沟北侧海底地下水排泄量大于海水入渗量,但处于同一个数量级。(4)数值模拟方法研究海水-地下水交换规律。利用数值模拟软件MARUN,对潮沟北侧地下水流进行模拟。观测井的水位观测值与模拟值拟合良好,在此基础上,根据模拟结果,对含水层中地下水流动特征和盐分分布特征做了初步分析。
[Abstract]:Reed swamp wetland is an important ecosystem in the intertidal zone. The study area is located at the muddy tidal flat of Yanghe River estuary in Jiaozhou Bay, and a large number of reeds are distributed in the sampling area. For comparative analysis of their hydrochemical characteristics. Observation wells are arranged at the tidal flat to observe the groundwater level, and the regularity of the exchange between seawater and groundwater is analyzed. The following results are obtained from the following four aspects: 1) study on the hydrochemical characteristics of the Guangtan area. Due to the effects of evaporation and the dilution of the high tide of the sea tide, The concentration of main ions is directly proportional to the distance to the tidal channel. The mixing of surface water makes the ratio of HCO _ 3 / Cl-K _ (+) K _ (+) ~ (2 +) ~ (2 +) ~ (2 +) ~ (2 +) on the high side, while the content of nitrate nitrogen is low, and the content of nitrite nitrogen and ammonium nitrogen is higher. Ammonium nitrogen is obviously larger than nitrite nitrogen, where denitrification is stronger; The content of Cu ~ (2 +) Cr ~ (2 +) CD in sediment pore water conforms to or is close to three kinds of groundwater quality standards. The correlation analysis shows that the Zn ~ (2 +) Cr ~ (2 +) Pb ~ (2 +) may have the same source. (2) A comparative study of water chemistry between the bare beach and the Reed distribution area, due to the difference of evaporation effect between them, Except for HCO3- and Hg, the concentrations of most of the major ions and heavy metals in the groundwater of Guangtan were higher than those in the Reed. Plant respiration and decomposition of organic matter led to the higher concentration of HCO3- in the groundwater of Reed region. It also shows that the growth of Reed can enrich Hg, because of the anaerobic environment of sediment and the growth of aquatic plants, the concentration of inorganic phosphorus in the groundwater of Reed area is higher than that of bare beach. The migration direction of main ions is opposite in Reed region and light beach area, and the migration direction of heavy metals in Reed and Reed area is basically the same, and the ORP fluctuation in Reed region is relatively small. Using hydraulic gradient method to study the law of seawater-groundwater exchange. The muddy tidal flat with a lower slope is beneficial to the development of permeable surface. At the high tide, seawater is more likely to seep into the intertidal aquifer. At low tide, the groundwater in the aquifer is more easily discharged to the sea. Using the hydraulic gradient method to calculate the sea water-groundwater exchange between the north and south sides of the trench, it is found that the amount of groundwater discharged from the sea bottom in the north side of the trench is greater than that in the sea water. But at the same order of magnitude.) numerical simulation method is used to study the law of seawater-groundwater exchange. The groundwater flow on the north side of the trench is simulated by using the numerical simulation software Marun. The water level observation value of the observation well fits well with the simulated value, and on this basis, Based on the simulation results, the characteristics of groundwater flow and salt distribution in the aquifer are preliminarily analyzed.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P641.3;X143;P342

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