江苏宜兴大港河水质变化对苦草遗传多样性和遗传结构影响分析

发布时间：2018-08-05 13:42

【摘要】：太湖是中国五大淡水湖之一,位于长江三角洲南缘。太湖流域人口密度大,工农业迅速发展,生活污水、农业废水等排放量增加,导致流入污染物的总量远远超过太湖整体纳污能力。太湖水质持续为V类甚至劣V类,富营养化程度严重。相关研究表明,入湖河道污染物的输入是造成太湖污染的主要来源之一,由入湖河道输入太湖的污染物占总量的80%,其中总氮输入量达90%以上。对入湖河道的生态治理是控制太湖污染和富营养化的重要工程。太湖共连接200多条河流,其中大港河是主要入湖支流之一,位于宜兴市丁蜀镇大港村,全长9.4km。河流两岸由西至东分布有林地、农田、村庄,是一条典型的集生活污水和农业面源污染的河流,水质具有明显的梯度变化特征。通过对大港河水质变化进行研究,可为大港河水生态修复和水资源管理提供参考依据。在富营养化水体中,水生植物生长、繁殖受到抑制,种群数量和种类大量减少,导致水生态系统失衡等严重生态问题。水生植物中沉水植物对于环境变化的反应较为敏感,对水环境质量具有比较强的指示作用。苦草(Vallisneria natans)为水鳖科(Hydrocharitaceae)苦草属多年生无茎沉水植物,是湿地生态修复的重要工具种之一。水体营养盐浓度显著影响苦草生长,当营养盐浓度过高时,将会削弱苦草光合作用,降低苦草根系活力等。为探究大港河水质梯度变化过程中,苦草种群数量减少以及其适应性下降的遗传基础。本实验在大港河从源头汇水区至入湖河口区采集水样、苦草植株以及底泥,对样品的氮、磷营养盐含量变化进行分析。同时,采用nSSR和cpSSR微卫星分子标记研究大港河顺流分布的6个苦草居群遗传多样性和遗传结构。得出以下主要结果:(1)大港河主河道各样点7个指标主要为逐渐增加的变化趋势。根据《地表水环境质量标准》(GB 3838—2002),大港河TN在第1样点平均值为0.88 mg/L,优于Ⅲ类水质标准,而第10样点已高达4.76mg/L,为劣Ⅴ类水质标准;水体中TP含量第1样点为0.21mg/L,为Ⅲ类水质标准,而第10样点上升至0.6 mg/L,,远高于Ⅴ类水标准,为劣V类;COD、NH3-N、NO3-N、PO43-均值在六个样点间呈明显逐渐上升趋势,而溶解氧变化趋势不明显。在大港河主要7条入河支浜的水质监测结果中,分布于农田、村庄、林地的支浜,其TN为Ⅴ类-劣Ⅴ类水质标准,TP总体为Ⅲ类水质标准。大港河水质由Ⅲ逐渐恶化为Ⅴ类-劣Ⅴ类。(2)6个样点的苦草所含TN、TP含量变化趋势是顺着水流方向逐渐升高。样点Ⅰ苦草TN为19 mg/g,至样点Ⅵ升高为25.7 mg/g;样点Ⅰ苦草所含TP含量为1.57 mg/g,样点Ⅵ升高至2.46 mg/g。(3)底泥营养盐在6个样点间呈依次递增的变化趋势,分别在样点Ⅰ为最低值,而在样点Ⅵ达到最高值。样点Ⅰ底泥所含TN含量为0.8 mg/g,样点Ⅵ升高至2.1 mg/g;样点Ⅰ所含TP含量为0.632 mg/g,样点Ⅵ升高为1.199 mg/g;样点Ⅰ所含有机碳含量为10.3 mg/g,样点Ⅵ升高为20.0 mg/g。(4)大港河六个苦草居群nSSR分析中,共检测出140个等位基因,其中每个微卫星位点有2—7个等位基因数,并且7对有多型的引物共可扩增出49个多态性片段,期望杂合度 He 分别为 0.436、0.375、0.353、0.298、0.294、0.297、0.342。苦草居群cpSSR分析中,共检测出187个等位基因,其中每个位点有2—7个等位基因数,平均为3.12个,且10对有多型的引物共可扩增出48个多态性片段,期望杂合度He结果分别为0.450、0.474、0.431、0.350、0.299、0.276。(5)核基因组遗传分化系数Fst为0.0715,即苦草种群有92.85%的遗传变异存在于种群内,仅有7.15%存在于种群间;叶绿体基因组遗传分化系数Fst为0.0675,显示有93.25%遗传变异主要存在于种群内,6.75%的遗传变异存在于种群间。(6)大港河流域人口密度大以及农业生产活动强度高,导致生活污水和农业面源污染增加,造成河流下游区水体恶化,富营养化程度严重。苦草受高浓度营养盐影响,其生存受到影响,种群遗传多样性水平降低,对环境变化的适应能力和竞争力减弱。
[Abstract]:Taihu is one of the five largest freshwater lakes in China, located in the southern margin of the Yangtze River Delta. The population density of the Taihu river basin is large, industrial and agricultural rapid development, domestic sewage and agricultural wastewater increase, resulting in the total amount of pollutants flowing far more than the overall capacity of Taihu. The water quality in Taihu is V or even inferior V, and the degree of eutrophication is serious. Related research The study shows that the input of the pollutants in the river channel is one of the main sources of pollution in Taihu. The input of the pollutants into Taihu is 80% of the total amount, of which the total nitrogen input is over 90%. The ecological control of the river entry to the lake is an important project to control the pollution and eutrophication of Taihu. More than 200 rivers are connected in Taihu, including the Dagang The river, one of the main tributaries in the lake, is located in Dagang village, Dagang Town, Dagang Town, Yixing. The whole long 9.4km. river has forestland, farmland and village from west to East. It is a typical river with domestic sewage and agricultural non-point source pollution. The water quality has obvious gradient characteristics. Through the study of the quality of the river water, it can be used for the Dagang river. In eutrophic water, in eutrophic water, the growth and reproduction of aquatic plants are inhibited, the number and species of the population are reduced, and the water ecosystem is unbalance. The aquatic plants are sensitive to the environmental changes and have a strong finger on the quality of water environment. Vallisneria natans is a perennial non stem submerged plant of the genus Hydrocharitaceae. It is one of the important tools for the ecological restoration of the wetland. The concentration of nutrients in the water body significantly affects the growth of the sore grass. When the concentration of the nutrient salt is too high, it will weaken the photosynthesis of the sore grass and reduce the vitality of the root of the sore grass. In the process of water quality gradient change, the genetic basis of the decrease in the number of sac population and the decrease of its adaptability. In this experiment, the changes of nitrogen and phosphorus content in the samples were analyzed by collecting water samples, slime plants and sediment in the Dagang River from the source water area to the Lake estuary. In the same time, the nSSR and cpSSR microsatellite markers were used for the study. The main results are as follows: (1) the 7 indexes of the main channel of the main river of Dagang River are mainly increasing trend. According to the standard of surface water environmental quality (GB 3838 - 2002), the average value of Dagang River TN at first sample points is 0.88 mg/L, which is superior to class III water quality standard, and the third is higher than Class III water quality standard. The 10 point has been up to 4.76mg/L, which is a grade V water quality standard. The first sample point of water content in water is 0.21mg/L, which is class III water quality standard, and tenth sample points rise to 0.6 mg/L, which is far higher than Class V water standard, which is inferior V; COD, NH3-N, NO3-N, PO43- mean gradually rising trend between six samples, but the change trend of dissolved oxygen is not obvious. In Dagang In the water quality monitoring results of 7 Main River Branch Creek, the river water quality is distributed in farmland, village and woodland. The TN is class V - grade grade V water quality standard, and TP is class III water quality standard. The quality of Dagang river is gradually deteriorated to class V class V class V. (2) the 6 samples of bitter grass contain TN, and the trend of TP content change is gradually rising along the direction of water flow. The TN of point I was 19 mg/g, the sample point VI increased to 25.7 mg/g, the content of TP in the sample point I was 1.57 mg/g, the sample point VI increased to 2.46 mg/g. (3), and the nutrient salt in the sediment was increasing in turn, the lowest at the sample point I, and the highest value at the sample point vi. The content of TN contained in the sample point I was 0.8 mg/g. Point VI increased to 2.1 mg/g; the content of TP in sample point I was 0.632 mg/g, the sample point VI was raised to 1.199 mg/g; the content of organic carbon in sample point I was 10.3 mg/g, and the sample point VI increased to 20 mg/g. (4) nSSR analysis of six Dagang River, and 140 alleles were detected in each microsatellite site, and there were 2 to 7 alleles and 7 at each microsatellite site. 49 polymorphic fragments were amplified from the polymorphic primers. The expected heterozygosity He was 0.436,0.375,0.353,0.298,0.294,0.297,0.342. in the cpSSR analysis of 0.436,0.375,0.353,0.298,0.294,0.297,0.342., respectively. A total of 2 to 7 alleles per locus were detected at each site, with an average of 3.12, and 10 pairs of polymorphic primers could be amplified by 48 more. The desired heterozygosity He results were 0.450,0.474,0.431,0.350,0.299,0.276. (5) the genetic differentiation coefficient Fst of the nuclear genome was 0.0715, that is, 92.85% of the genetic variation existed in the species and only 7.15% existed in the population, and the genetic segregation coefficient of the chloroplast genome was 0.0675, indicating that there were 93.25% genetic variations. In the population, 6.75% of the genetic variation existed between the population. (6) the large population density and the high intensity of agricultural production activity in the Dagang River Basin resulted in the increase of sewage and agricultural non-point source pollution, resulting in the deterioration of the water body and the serious eutrophication in the lower reaches of the river. The level of diversity decreases, and the adaptability and competitiveness of environmental change are weakened.
【学位授予单位】：南京大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X52;Q943.2

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