澎溪河回水区营养盐和叶绿素a的时空变化及其相互关系

发布时间：2018-03-18 05:28

本文选题：三峡库区　切入点：澎溪河回水区　出处：《西南大学》2015年硕士论文　论文类型：学位论文

【摘要】：在富营养化问题的研究与治理中,营养盐时空分布特征一直是富营养化研究工作者关注和研究的对象,同时也是确立富营养化水域治理措施的关键。三峡水库蓄水之后导致干流水体倒灌支流形成了面积广阔的回水区,支流库湾由原来的河流型转变为湖泊性。为了防洪的需要,三峡水库采取高水位运行(175m,11-第二年4月)、泄水期(5-6月中旬)、汛期低水位运行(145m,6～8月)、蓄水期(9-11月)、高水位运行的调度运行方式。在调度运行背景下,淹没的大量农田和消落带既是营养的汇,又是营养的源,对水体营养有补给作用。澎溪河作为三峡库区消落区面积最大的支流,其营养盐受地表径流输入、干流倒灌、底泥和消落带释放等多种因素的影响。为探讨三峡水库调度运行背景下,澎溪河回水区营养盐和叶绿素a时空变化及其相互关系,于2013年5月至2014年6月,在澎溪河高阳平湖进行了定点高频监测,并开展了两次全流域调查。主要得到如下结论：(1)冬季高阳平湖氮磷营养盐浓度最高,但是由于温度低而没有发生水华,水质较好,处于中营养水平。春末夏初(2014年4月-5月中旬)高阳平湖水体富营养化最严重,水体处于中度富营养水平,5月10日甚至达到了重度富营养化。水体富营养状态指数随时间变化趋势与叶绿素a的变化情况一致。营养盐浓度在不同水位条件下差异较大,NH4+-N在高水位期含量最小,在0.02 mg.L-1以下,水华期间最高,主要来源于水体内部的氮循环；硝氮和总氮在2014年5月泄水期最高,高水位期次之,低水位期最低,干流倒灌输入是高阳平湖硝氮和溶解性磷的主要来源。高水位期,高阳平湖硝氮和溶解性磷在总氮和总磷中所占比重分别为71.4%～95.4%和42.7%-94.4%,是高阳平湖氮磷的主要组成部分,而降雨期间总磷的浓度高于高水位期,除干流倒灌外,降雨引起的地表径流输入是其另一个来源。(2)高阳平湖水体分层受气温和水位变化的双重影响。水体热分层形成于春季(2014年3月2日-5月10日),从3月初开始水温出现水体弱分层现象,之后表底层温差逐渐增大,4月下旬形成稳定的分层结构。5月下旬分层结构被三峡水库泄水引起的强扰动破坏,温跃层逐渐消失。混合层深度增加,从2014年5月10日的0.32m增加至29日的8.5m。仲夏水体分层最明显,6月表底层温差高达10.4℃。夏末(9月中旬),水体分层开始逐渐消亡,冬季没有分层。(3)水温分层是影响高阳平湖营养盐和叶绿素垂向分布的主要因素。水体没有分层情况下,表、中、底层营养盐和叶绿素a无明显差异,叶绿素a浓度小于3 μ,g.L-1。春季,随着水温分层的发生和发展,表层叶绿素a在69天内从3μg.L-1骤增至183.73μg.L-1,并爆发水华。之后水体分层结构被破坏,叶绿素a下降。营养盐垂向分布与水体的分层情况有关,水体没有分层情况下,各水层营养盐含量没有明显差异；水体分层以后,表、中、底层营养盐浓度差增大。(4)澎溪河大部分断面水质处于轻度富营养水平,有个别断面甚至达到重度富营养。泄水前后水体富营养化空间差异明显,泄水初期上游断面水质较差,综合营养指数从下游到上游呈增大趋势；泄水之后中下游断面水质较差,沿程综合营养指数变化趋势呈抛物线型。水质变化主要受藻类水华影响,沿程水质变化与叶绿素a浓度变化一致。(5)叶绿素a浓度的变化准确反映了水华爆发的位置和严重程度,泄水初期,叶绿素a峰值出现在水华爆发最严重的断面6和断面7,泄水之后,其峰值出现在发生水华的断面2和断面4,随着泄水过程中水位的下降,澎溪河水华爆发的区域有向下游迁移的趋势。(6)总体来看无论泄水初期还是泄水后,三峡库区长江干流营养盐含量均高于澎溪河支流。澎溪河支流营养盐浓度从下游到上游呈下降趋势。靠近河口断面硝氮浓度大于2mg·L-1,上游断面不到0.1mg·L-1,河口断面溶解性总磷高达0.14mg·L-1,上游断面低于0.06mg·L-1,干流输入是澎溪河营养盐的主要来源。垂直方向上,4月靠近河口断面的中层营养盐浓度最高,尤其是硝氮和溶解性总磷等可溶态营养盐,由此说明干流水体从中层潜入澎溪河库湾；7月主要表现为中下层浓度高于上层,说明干流从中底层潜入。(7)澎溪河沉积物中高水位期检出了41种磷脂脂肪酸,其中细菌有38种,放线菌2种,真菌1种；7月泄水之后总共检出磷脂脂肪酸35种,其中细菌有32种,真菌和放线菌数量与泄水初期相同,总体上高水位和低水位条件下,澎溪河沉积物微生物种类没有显著变化(P0.5),但是水位降低后磷脂脂肪酸的总含量除PX-2、PX-3、PX-7受流速和沉积物质地影响较低外,其它断面都明显增加,同时各个断面细菌的特征磷脂脂肪酸含量也普遍增加。高水位和低水位情况下,均是厌氧细菌占优势,但是水位降低后好氧细菌丰度有一定的增加,说明水位变化对微生物生物量和细菌结构组成有影响。
[Abstract]:In the research and control of eutrophication in the temporal and spatial distribution of nutrition salt has been the object of eutrophication research workers concerned and researched, but also the key to establish the eutrophic water control measures. After the impoundment of Three Gorges Reservoir in river water from tributaries formed backwater area of the vast area, change from River tributaries bay the lake. In order to flood control needs, take the high water level of Three Gorges reservoir (175m 11-, April second), drainage period (5-6 month), the low water level operation in flood season (145m, 6~8), storage period (9-11 months), and operation mode of high water level operation. In the operation under the background, a lot of farmland flooded and riparian zone is not only the nutrient sink is the source of nutrition, replenishment effect on water nutrition. As the Pengxi River Three Gorges Reservoir area is the largest tributary, the nutrient input by surface runoff, dry Flow and sediment intrusion, eliminate the impact of various factors such as the fall release. To Three Gorges reservoir operation under the background of a, temporal and spatial variation of Pengxi River backwater area and the relationship between nutrients and chlorophyll, from May 2013 to June 2014, the fixed frequency monitoring in Pengxi River Gao Yang in Pinghu, and carried out two times the whole basin the investigation. The main conclusions are as follows: (1) the winter Gao Yang Pinghu nitrogen and phosphorus concentration is highest, but due to low temperature and no bloom, the water quality is good, in the nutritional level. In late spring and early summer (April 2014 -5 month) Gao Yang Pinghu the most serious water eutrophication eutrophication, water eutrophication level is moderate, even in May 10th reached the severe eutrophication. Changes consistent eutrophic state index with the trend of the temporal variation of a and chlorophyll. The nutrient concentration in different water level conditions, NH4 +-N in the high water level The content of the minimum period, below 0.02 mg.L-1, the highest nitrogen cycle in the bloom period, the main source of water; nitrate nitrogen and total nitrogen in May 2014 the highest discharge period, high water period, low water period is lowest, main stream reverse input is main source of Gaoyang Pinghu nitrate nitrogen and dissolved phosphorus. The high water level period Pinghu Gaoyang, nitrate nitrogen and dissolved phosphorus in total nitrogen and total phosphorus in the proportion was 71.4% ~ 95.4% and 42.7%-94.4%, is the main part of Pinghu Gaoyang nitrogen and phosphorus, and the concentration of phosphorus is higher than that of rainfall during the high water period, in addition to the main stream intrusion, surface runoff caused by the rainfall input is another source of. (2) the dual influence of Pinghu Gaoyang stratification by the temperature variation. The thermal stratification was formed in the spring (March 2, 2014 -5 10) from the beginning of March, the water temperature stratification is weak, after the surface and bottom temperature increase, the 4 month Ten form layered structure hierarchical structure of.5 in late August the Three Gorges reservoir water caused by strong disturbance, Wen Yueceng gradually disappear. The mixed layer depth increases, the most obvious increased from 0.32m in May 10, 2014 to 29 8.5m. summer water layer, 6 lunar bottom temperature difference reaches 10.4 degrees. At the end of the summer (mid September), stratified start gradually disappearing, winter is not stratified. (3) the water temperature stratification is the influence of Pinghu Gaoyang nutrients and chlorophyll vertical distribution. The main factors of water table, no delamination case, the underlying nutrient and chlorophyll a had no significant difference in chlorophyll a concentration less than 3 g.L-1., the spring, with the occurrence and development of water temperature stratification and the surface chlorophyll a in 69 days from 3 g.L-1 to 183.73 at g.L-1, and the outbreak of water bloom. After stratification structure was destroyed, chlorophyll a decreased. Nutrient vertical layers related to the distribution of water, water There is no hierarchical case, there is no significant difference in the water content of nutrient; water after stratification, table, and the underlying nutrient concentration difference increases. (4) the Pengxi River water quality in most mild eutrophic level, individual sections even to severe eutrophication. The difference before and after the water eutrophication was the initial discharge, upstream water quality is poor, the comprehensive nutrition index increases from downstream to upstream; discharge after the downstream water quality is poor, the comprehensive nutrition index trend of a parabola. The change of water quality is mainly affected by the algae bloom, along with variations of chlorophyll a concentration. The process of water quality variation of chlorophyll a (5) the concentration of algal blooms accurately reflect the location and severity, early discharge, chlorophyll a peak in the bloom of the worst outbreak of section 6 and section 7, after discharge, the peak appeared in the hair The 2 section students and section 4, with the decline of water level in the process of water, the outbreak of Pengxi River China region downstream migration trend. (6) the overall discharge or whether early discharge after nutrient contents were higher than that of the Yangtze River Three Gorges Reservoir of Pengxi River tributary. The Pengxi River tributary nutrient concentration from downstream to upstream declined. Near the estuary section of nitrate nitrogen concentration is greater than 2mg, L-1, 0.1mg, L-1 to the upstream cross section, the section dissolved total phosphorus reached 0.14mg - L-1, 0.06mg - L-1 lower than the upstream section, river input is the main source of Pengxi River nutrients. In vertical direction, close to April the middle section of estuarine nutrient concentration is highest, especially nitrate nitrogen and dissolved total phosphorus and soluble nutrients, the river water from the middle into the Pengxi River Bay; July is mainly in the lower concentration was higher, indicating that stem from the bottom flow Into the layer. (7) the Pengxi River Sediments in the high water level detection of 41 kinds of phospholipid fatty acids, of which there are 38 kinds of bacteria, actinomycetes and 2 species, 1 species of fungi; in July after a total discharge detection of phospholipid fatty acid 35, of which there are 32 kinds of bacteria, fungi and actinomycetes and early discharge the same, high water level and low water level conditions in general, there was no significant change in Pengxi River sediment microbial species (P0.5), but the content of total phospholipid fatty acid level decreased after the removal of PX-2, PX-3, PX-7 by flow velocity and sediment of the lower section, the other is significantly increased, while characteristics of phospholipid fatty acid content each section of bacteria are generally increasing. The high water level and low water level conditions are anaerobic bacteria dominant, but the water level decreased after aerobic bacterial abundance have increased, indicating the change of water level has an effect on microbial biomass and bacterial composition.

【学位授予单位】：西南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X524

【引证文献】