太湖水环境特征及沉积物有机质来源识别
发布时间：2018-08-11 12:20
【摘要】：太湖处于长江三角洲地区,是我国区域人口密度最高、经济最发达的地区之一,快速发展的工业、农业和城市化进程加剧,使太湖水环境污染日趋严重,现已最富营养化严重的湖泊之一。与深水湖泊相比,浅水湖泊单位体积的水体拥有更大面积的水-沉积物界面,而沉积物鲜明的“源-汇”特征,使其不仅可以接纳储存污染物,也可导致水体二次污染。太湖是典型的浅水湖泊,沉积物中蓄积了大量的营养盐和有机质,当沉积物受到风浪扰动和生物活动干扰时,营养盐和有机质会再次进入水体,形成湖泊内源污染负荷,加剧湖泊富营养化程度,提高蓝藻水华爆发的可能性。因此研究水体中有机质来源对评估水环境质量状况,研究湖体营养质量变化具有重要实践意义,也为太湖及浅水型湖泊治理提供理论依据。本文将太湖划分为北部湖区(竺山湾、梅粱湾、贡湖)；西部湖区(西部沿岸带)；南部湖区(南部沿岸带)；东部湖区(东太湖、胥湖)；湖心湖区共五个湖区,对五个湖区进行水样采样和表层沉积物采集,开展太湖水环境现状调查,并对太湖表层沉积物的有机质来源进行了判断。基于水样的总氮(TN)、总磷(TP)、总有机碳(TOC)、溶解氧(DO)、透明度(SD)、酸碱度(pH)等指标,使用单因子评价法和综合污染指数法进行水质评价。评价结果显示,太湖整体水质达到地表Ⅳ类水标准,呈中度污染状态,主要污染因子为TN和TP；重点污染区域有竺山湾、梅梁湖和西部湖岸ANOVA分析显示,北部湖区TN显著高于湖心湖区(P0.05),TP显著高于东部湖区(P0.05),TOC显著高于东部、南部湖区(P0.05)；东部湖区TOC显著低于北部湖区和西部湖区(P0.05)；西部湖区TP显著高于南部湖区和东部湖区(P0.05), TOC显著高于南部湖区(P0.05)；五个湖区DO差别不显著。结果表明,北部和西部湖区受到入湖河流影响,营养负荷高,同时受到风浪和水动力影响,污染物易聚集；东部和南部湖区高等水生植物繁茂,具备良好的水质自净功能,水环境状况良好。基于全湖分布的沉积物稳定碳同位素(δ13C)、稳定氮同位素(δ15N)、总有机碳(TOC)、总氮(TN)含量,探讨五个湖区各元素空间分布和湖区差异。其中东部湖区δ13C与δ15N值显著低于其他湖区(P0.05)；C/N比全湖各湖区没有显著差异(P0.05)；太湖TOC与TN正相关。结果表明,由于东部湖区水生维管植物群落比其他湖区分布更广泛,其沉积物δ13C偏重,δ15N偏轻；北部湖区受到藻类爆发影响,沉积物δ13C偏轻；沉积物C/N符合藻类和浮游植物特征,显示五个湖区有机质来源主要为藻类和浮游植物。此外,我们采用13C和C/N比的二元分析方法,定性判断沉积物有机质来源,并使用同位素端元模型计算贡献率(f)。结果显示沉积物有机质主要来源为湖体淡水藻类和水生植物,陆源来源不明显。淡水藻类对湖泊有机质贡献率为65%；其中竺山湾沉积物有机质藻类贡献率(fa)为100%,北部湖区和西部湖区fa分别为72.1%和72.7%,东部湖区fa和水生植物沉积物有机质贡献率(fv)相当,东太湖近岸水生植被茂密的湖荡内,fv高达93.1%。水环境特征和有机质来源识别表明,各湖区水环境特征差异明显,水环境质量受到入湖河流影响；湖区沉积物碳氮元素空间分布特征与湖区植被分布特点相一致；湖泊沉积物有机质主要来源为内源,淡水藻类对沉积物有机质的贡献率为65%。
[Abstract]:Located in the Yangtze River Delta, Lake Taihu is one of the most densely populated and economically developed areas in China. The rapid development of industry, agriculture and urbanization has aggravated the pollution of water environment in Lake Taihu, which has become one of the most eutrophic lakes. Compared with deep-water lakes, shallow-water lakes have a larger unit volume of water. Lake Taihu is a typical shallow lake with a large amount of nutrients and organic matter in the sediments. When the sediments are disturbed by wind and waves and biological activities, nutrients and organic matter are accumulated. Therefore, it is of great practical significance to study the source of organic matter in the water body for assessing the water environment quality and studying the changes of nutrient quality in the lake, and to provide theoretical basis for the control of Taihu Lake and shallow lakes. According to this paper, Taihu Lake is divided into five Lake areas: North Lake area (Zhushan Bay, Meiliang Bay, Gonghu); West Lake area (west coastal zone); South Lake area (south coastal zone); East Lake area (east Taihu Lake, Xuhu Lake); Lake Center Lake area, five Lake areas are sampled and surface sediments are collected to investigate the water environment of Taihu Lake. Based on the indexes of total nitrogen (TN), total phosphorus (TP), total organic carbon (TOC), dissolved oxygen (DO), transparency (SD), acidity and alkalinity (pH), the water quality of Taihu Lake was evaluated by single factor method and comprehensive pollution index method. The main pollution factors were TN and TP, and the major pollution areas were Zhushan Bay, Meiliang Lake and Western lakeshore ANOVA analysis showed that TN in the Northern Lake area was significantly higher than that in the Central Lake area (P 0.05), TP was significantly higher than that in the eastern Lake area (P 0.05), TOC was significantly higher in the southern Lake area (P 0.05), and TOC in the eastern Lake area was significantly lower than that in the Northern Lake area and the Western Lake area (P 0.05). There was no significant difference in DO between the five Lake areas. The results showed that the northern and Western Lake areas were affected by the inflow river, the nutrient load was high, and the pollutants were easily accumulated under the influence of wind wave and hydrodynamic force. Based on the distribution of stable carbon isotope (delta 13C), stable nitrogen isotope (delta 15N), total organic carbon (TOC), total nitrogen (TN) in the sediments of the whole lake, the spatial distribution of elements in the five Lake areas and the differences between the lake areas were discussed. The values of delta 13C and delta 15N in the eastern Lake area were significantly lower than those in other lakes. The results showed that the distribution of aquatic vascular plant communities in the eastern Lake area was wider than that in other lake areas, the sediments of the eastern Lake area were heavier and the sediments of the Northern Lake area were slightly affected by algae outbreaks, while the sediments of the Northern Lake area were slightly affected by algae outbreaks and the sediments of the sediments were slightly affected by algae outbreaks. The characteristics of phytoplankton indicate that the main sources of organic matter in the five lakes are algae and phytoplankton. In addition, the source of organic matter in the sediments is qualitatively determined by using the binary analysis method of 13C and C/N ratios, and the contribution rate (f) is calculated by using the isotope end-element model. Freshwater algae contributed 65% of the organic matter in the lake, including 100% in the sediments of Zhushan Bay, 72.1% in the Northern Lake and 72.7% in the western lake, the same in the eastern Lake as in the sediments of aquatic plants (fv). FV is up to 93.1%. identification of water environment characteristics and organic matter sources shows that there are obvious differences among the lake areas, and the quality of water environment is affected by the river entering the lake; the spatial distribution characteristics of carbon and nitrogen elements in the lake sediments are consistent with the distribution characteristics of vegetation in the lake area; the main source of organic matter in the lake sediments is endogenous, and the fresh water algae is organic to the sediments. The contribution rate of quality is 65%.
【学位授予单位】：南京大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X524
本文编号：2176976
[Abstract]:Located in the Yangtze River Delta, Lake Taihu is one of the most densely populated and economically developed areas in China. The rapid development of industry, agriculture and urbanization has aggravated the pollution of water environment in Lake Taihu, which has become one of the most eutrophic lakes. Compared with deep-water lakes, shallow-water lakes have a larger unit volume of water. Lake Taihu is a typical shallow lake with a large amount of nutrients and organic matter in the sediments. When the sediments are disturbed by wind and waves and biological activities, nutrients and organic matter are accumulated. Therefore, it is of great practical significance to study the source of organic matter in the water body for assessing the water environment quality and studying the changes of nutrient quality in the lake, and to provide theoretical basis for the control of Taihu Lake and shallow lakes. According to this paper, Taihu Lake is divided into five Lake areas: North Lake area (Zhushan Bay, Meiliang Bay, Gonghu); West Lake area (west coastal zone); South Lake area (south coastal zone); East Lake area (east Taihu Lake, Xuhu Lake); Lake Center Lake area, five Lake areas are sampled and surface sediments are collected to investigate the water environment of Taihu Lake. Based on the indexes of total nitrogen (TN), total phosphorus (TP), total organic carbon (TOC), dissolved oxygen (DO), transparency (SD), acidity and alkalinity (pH), the water quality of Taihu Lake was evaluated by single factor method and comprehensive pollution index method. The main pollution factors were TN and TP, and the major pollution areas were Zhushan Bay, Meiliang Lake and Western lakeshore ANOVA analysis showed that TN in the Northern Lake area was significantly higher than that in the Central Lake area (P 0.05), TP was significantly higher than that in the eastern Lake area (P 0.05), TOC was significantly higher in the southern Lake area (P 0.05), and TOC in the eastern Lake area was significantly lower than that in the Northern Lake area and the Western Lake area (P 0.05). There was no significant difference in DO between the five Lake areas. The results showed that the northern and Western Lake areas were affected by the inflow river, the nutrient load was high, and the pollutants were easily accumulated under the influence of wind wave and hydrodynamic force. Based on the distribution of stable carbon isotope (delta 13C), stable nitrogen isotope (delta 15N), total organic carbon (TOC), total nitrogen (TN) in the sediments of the whole lake, the spatial distribution of elements in the five Lake areas and the differences between the lake areas were discussed. The values of delta 13C and delta 15N in the eastern Lake area were significantly lower than those in other lakes. The results showed that the distribution of aquatic vascular plant communities in the eastern Lake area was wider than that in other lake areas, the sediments of the eastern Lake area were heavier and the sediments of the Northern Lake area were slightly affected by algae outbreaks, while the sediments of the Northern Lake area were slightly affected by algae outbreaks and the sediments of the sediments were slightly affected by algae outbreaks. The characteristics of phytoplankton indicate that the main sources of organic matter in the five lakes are algae and phytoplankton. In addition, the source of organic matter in the sediments is qualitatively determined by using the binary analysis method of 13C and C/N ratios, and the contribution rate (f) is calculated by using the isotope end-element model. Freshwater algae contributed 65% of the organic matter in the lake, including 100% in the sediments of Zhushan Bay, 72.1% in the Northern Lake and 72.7% in the western lake, the same in the eastern Lake as in the sediments of aquatic plants (fv). FV is up to 93.1%. identification of water environment characteristics and organic matter sources shows that there are obvious differences among the lake areas, and the quality of water environment is affected by the river entering the lake; the spatial distribution characteristics of carbon and nitrogen elements in the lake sediments are consistent with the distribution characteristics of vegetation in the lake area; the main source of organic matter in the lake sediments is endogenous, and the fresh water algae is organic to the sediments. The contribution rate of quality is 65%.
【学位授予单位】：南京大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X524
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