南流江城市河流沉积物营养盐富集特征及污染评价研究

发布时间：2018-06-24 19:51

本文选题：南流江 + 城市河段　；参考：《广西师范学院》2015年硕士论文

【摘要】：随着南流江流域城镇化进程的加速,农村人口大量涌入城市,城市化面积突飞猛进般扩张及人口激增,一方面造成典型城市河流天然汇水区域大幅减少,另一方面工业废水、生活污水的大量排放,氮、磷等营养元素随污水进入水体及底泥中,一部分发生化学转化为其他污染物,一部分被浮游植物,如蓝藻等吸收富集,其余大部分进入底泥富集,在一定条件下释放,造成二次污染。南流江是广西北部湾独流入海诸河中流域面积最广、水量最丰富的河流,流域面积9705.8平方公里,多年平均径流量77.4亿立方米。然而,其河水流速缓慢,自净能力差,水生态环境十分脆弱。近年来,由于流域城镇快速发展,周边厂矿、流域农业发展及居民生活对河流造成严重水体污染,河流水质不断恶化。本文通过对南流江流域上、中、下游城区河段(分别为玉州区、博白县、合浦县)典型断面上覆水与底泥营养盐调查分析,揭示了流域城区河段营养盐富集特征及影响因子,并对流域营养盐污染状况进行了评价,为流域城区河段水生态环境改善提供科学建议。本文主要结论如下:1.从上覆水及底泥营养盐富集特征上看,全流域上中下游不同断面DO平均水平为7.02mg/L,p H为6.8mg/L,上覆水TP平均含量为1.87mg/L,粒度以粉砂粒级为主,沉积物TN平均含量为1.2g/kg,TP为0.09g/kg,TOC为9.8g/kg,TC为17.4g/kg。营养盐含量具有排污口断面大于自然河流断面特点,DO、pH、沉积物TN、沉积物TP具有自上游向下游降低特点,而水体TP呈现相反变化。2.利用Pearson相关系数法对营养盐之间相关性进行了探讨。得出沉积物TN与TP之间、沉积物TP与上覆水TP、TOC与TC间均具有显著相关关系,而TOC与DO之间具有显著负相关关系。沉积物TN、TP含量呈现出与粘土颗粒负相关、粉砂颗粒正相关关系。3.利用沉积物污染分级评价法、单因子污染指数及内梅罗综合污染指数法对流域沉积物进行污染评价。得出合浦河段断面最优,博白河段内梅罗指数普遍位于1以上,污染状况最差。排污口处底泥污染较自然河流沉积物明显严重。4.河岸缓冲带对于河流水体与河岸物质交换、改善河流水生态环境具有重要意义。本文认为合理规划河岸缓冲带类型及宽度及跨流域调水是解决南流江流域水生态问题的重要途径。
[Abstract]:With the acceleration of urbanization in the Nanliu River Basin, the rural population is pouring into the city, and the urbanization area is expanding by leaps and bounds and the population is increasing rapidly. On the one hand, the natural catchment area of the typical urban rivers has been greatly reduced, on the other hand, the industrial wastewater has been greatly reduced. A large amount of domestic sewage discharge, nitrogen, phosphorus and other nutrients into the water and sediment with the sewage, some chemical transformation into other pollutants, some phytoplankton, such as cyanobacteria absorption and enrichment, the rest into sediment enrichment, Release under certain conditions, resulting in secondary pollution. The Nanliu River is the most extensive and abundant river in the Beibu Gulf of Guangxi, with an area of 9705.8 square kilometers and an average annual runoff of 7.74 billion cubic meters. However, its water flow rate is slow, its self-purification ability is poor, the water ecological environment is very fragile. In recent years, due to the rapid development of cities and towns, the surrounding factories and mines, the agricultural development of the basin and the residents' lives, the river has been polluted seriously, and the water quality of the river has been deteriorating. Based on the investigation and analysis of the overlying water and sediment nutrients on the typical sections of the upper, middle and lower reaches of the Nanliu River Basin (Yuzhou District, Bobai County, Hepu County, respectively), the characteristics of nutrient enrichment and the influencing factors in the river reach of the basin are revealed in this paper. The status of nutrient pollution in the river basin was evaluated to provide scientific advice for the improvement of the ecological environment of water in the river reach of the watershed. The main conclusions of this paper are as follows: 1. According to the characteristics of nutrient enrichment in overlying water and sediment, the average do level of different sections in the upper and lower reaches of the basin is 7.02 mg / L / L H is 6.8 mg / L, the average content of TP in overlying water is 1.87 mg / L, the grain size is mainly silty sand, and the average TN content of sediment is 1.2 g / kg TP = 0.09 g / kg ~ (-1) TOC = 9.8 g / kg 路kg ~ (-1) TC = 17.4 g / kg 路L ~ (-1). The nutrient content in the sediment was lower than that in the upstream and downstream, while the TP in the water showed the opposite change. 2. The nutrient content in the sewage outlet was larger than that in the natural river section, and the pH value of the sediment was higher than that of the natural river section. Pearson correlation coefficient method was used to study the correlation between nutrients. The results show that there is a significant correlation between TN and TP, TP and TOC and TC, while there is a significant negative correlation between TOC and do. The content of TNT TP in sediments was negatively correlated with clay particles and positively correlated with silt particles. The pollution assessment method of sediment pollution classification, single factor pollution index and Nemero comprehensive pollution index were used to evaluate the pollution of river basin sediments. It is concluded that the section of Hepu reach is the best, and the Mello index of Bobai reach is generally above 1, and the pollution is the worst. The sediment pollution at the sewage outlet is more serious than that of the natural river sediment. Riparian buffer zone is of great significance for the exchange of water body and river bank material and the improvement of river water ecological environment. In this paper, it is considered that rational planning of the type and width of riparian buffer zone and water transfer across river basins is an important way to solve the problem of water ecology in Nanliujiang River Basin.
【学位授予单位】：广西师范学院
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X824;X522

【参考文献】