湖滨缓冲带湿地基底形态修复研究

发布时间：2018-04-30 12:16

本文选题：湿地 + 水深　；参考：《东北林业大学》2015年硕士论文

【摘要】：基底是湿地植物的支撑者,同时也是微生物及底栖动物活动的场所,基底条件的改善是湿地生态修复的基础,而基底形态优化则是基底条件改善的重要举措。本文首先以典型凹形基底湿地为例研究了基底形态对湿地水体及底泥中营养盐分布的影响,研究发现湿地水体及沉积物中营养盐分布是不均匀的,其分布规律与上覆水深度有关。水体ρ(TN)和ρ(TP)随着上覆水深度的增加(基底高程的降低)呈现先降低再升高的趋势,在水深为30-50 cm位置处的水体中达到最低值,而表层底泥中w(TP)和w(TN)随着上覆水深度增加呈现升高趋势,在水深为70-80 cm位置处底泥中营养盐浓度最高。利用流体动力学软件Fluent对进入湿地的水体流态进行分析得出,湿地营养盐的分布受水流流态影响较大,而水体流态则受基底形态影响。然后,以典型凹形基底湿地为例研究了基底形态对暴雨径流污染净化特征的影响。营养盐随暴雨径流进入湿地,引起湿地水体营养盐浓度迅速升高。暴雨结束初期,湿地系统对水体中营养盐的削减以物理沉降为主,其后,湿地系统对水体中营养盐的削减以生物降解为主,这两个过程均受到基底理化条件的影响,而基底理化条件由基底形态结构引起。就湿地系统内部而言,存在“高效净化区”和“低效净化区”,基底的起伏变化引起湿地上覆水深度的变化,进而导致基底理化指标的差异,从而影响营养盐的净化效率。最后,在实验室内模拟构建5种不同形态基底(斜面型、平面型、凹面型、凸面型及多自然型基底),在典型水深(40cm)的条件下,研究了不同基底形态对“水体-底泥”系统营养盐的去除效果。研究发现不同基底形态实验组系统对总氮的去除率依次为28.84%、25.22%、27.07%、31.23%、35.23%；对总磷的去除率基本相同,只有略微差别,是由水生植物的摄取造成的。湿地基底形态的差异,导致底泥一水界面的有效比表面积不同,从而影响了基底生物膜的附着空间和底泥与水体交换程度,最终也会影响湿地系统对营养盐的净化效果。另外,基底形态结构还影响基底光的强弱分布,进而影响了水生植物的发育及生长,也导致了湿地系统对营养盐的去除效果的差异。
[Abstract]:The substrate is not only the support of wetland plants, but also the site of microorganism and benthic animal activity. The improvement of basal condition is the basis of wetland ecological restoration, and the optimization of basal morphology is an important measure to improve the base condition. In this paper, a typical concave base wetland is taken as an example to study the effect of substrate morphology on nutrient distribution in wetland water and sediment. It is found that the distribution of nutrient in wetland water and sediment is not uniform. Its distribution is related to the overlying water depth. With the increase of overlying water depth (decrease of basal elevation), the water body 蟻 (TNN) and 蟻 TPS) decreased first and then increased, and reached the lowest value in the water body where the water depth was 30-50 cm. However, the content of TP and TNN in the surface sediment increased with the increase of the overlying water depth, and the highest concentration of nutrients was found in the sediment at a depth of 70-80 cm. By using the fluid dynamics software Fluent to analyze the water flow pattern, it is concluded that the distribution of nutrients in the wetland is greatly affected by the water flow pattern, while the water flow pattern is affected by the basal morphology. Then, taking typical concave wetland as an example, the effects of substrate morphology on the pollution purification characteristics of rainstorm runoff were studied. The nutrient concentration of wetland water increased rapidly with the rainstorm runoff coming into the wetland. At the beginning of torrential rain, the reduction of nutrient in water by wetland system was mainly physical sedimentation, and then the reduction of nutrient in water by wetland system was mainly biodegradable. These two processes were affected by the physical and chemical conditions of substrate. The physical and chemical conditions of the substrate are caused by the morphological structure of the substrate. As far as the wetland system is concerned, there are "high efficiency purification areas" and "low efficiency purification areas". The fluctuation of the base causes the change of the overlying water depth of the wetland, and then leads to the difference of the physical and chemical indexes of the substrate, thus affecting the purification efficiency of the nutrient. Finally, five different types of substrates (inclined, plane, concave, convex and polynatural) were constructed in laboratory under typical water depth of 40 cm. The effect of different substrate morphology on nutrient removal in water-sediment system was studied. The results showed that the removal rate of total nitrogen in the experimental group with different substrate morphology was 28.84 ~ 25.22 ~ 27.07 and 31.2323 ~ 35.233.The removal rate of total phosphorus was basically the same and only slightly different, which was caused by the uptake of aquatic plants. The difference of substrate morphology leads to the difference of the effective specific surface area of the interface between sediment and water, which affects the adhesion space of the substrate biofilm and the exchange degree between sediment and water, and finally affects the purification effect of the wetland system on nutrient salt. In addition, the morphological structure of the substrate also affects the distribution of the intensity and intensity of the substrate light, thus affecting the development and growth of aquatic plants, which also leads to the difference of nutrient removal efficiency in the wetland system.
【学位授予单位】：东北林业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X171.4

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