支流河口水动力作用对三峡库区干支流营养盐交换的影响

发布时间：2018-05-06 13:28

本文选题：三峡水库 + 水动力　；参考：《华东师范大学》2014年硕士论文

【摘要】：于2012年8月至2013年7月,对三峡库区三条支流(草堂河、梅溪河、朱衣河)的水动力特征、营养盐、水温、浊度、叶绿素等参数进行为期一年的逐月观测。分析了支流河口水体分层的特征,定量估算了进出水体的流量大小,结合营养盐分布特征,探讨支流河口水动力特征对库区干支流营养盐交换、循环的影响。结果表明： (1)库区支流河口存在河口环流及水体分层现象,主要有上下分层、左右分层、多层倒灌等形式。低水位运行期河口水交换强烈,河口环流较强。进出支流河口水体的流速季节性变化较大,在5、6、7月流速大于其他月份。草堂河倒灌水体全年平均流速为0.083m/s,流出水体全年平均流速为0.095m/s；梅溪河倒灌水体全年平均流速为0.079m/s,流出水体全年平均流速也为0.079m/s；朱衣河倒灌水体全年平均流速为0.072m/s,流出水体全年平均流速为0.07m/s。三条支流的倒灌水体年平均流量分别为：草堂河730.55m3/s,梅溪河428.62m3/s,朱衣河426.75m3/s。高水位运行期河口进出流量较大。 (2)库区干流表层的营养盐浓度较高,其中DIN全年平均约为129.3Ｌmol/L,DSi全年平均约为119.5pmol/L,DIP全年平均约为3.42μmol/L。季节变化明显,尤其是磷酸盐,其浓度变化与三峡水位变化趋势一致。支流河口的营养盐浓度与长江干流表层水体的浓度接近,变化趋势也与长江干流表层水相似。其中DIN和磷酸盐的变化表现为：蓄水期和高水位运行期浓度低(DIN大约95-115μmol/L,磷酸盐大约0.4-2μmol/L),泄水期和低水位运行期浓度高(DIN大约135-175μmol/L,磷酸盐大约5-6μmol/L)。而硅酸盐浓度变化正好相反(蓄水期和高水位运行期浓度120-150μmol/L,泄水期和低水位运行期浓度90-100μmol/L)。草堂河、梅溪河、朱衣河的营养盐组成特征与长江干流相似,与源头水体差别较大。 (3)支流河口至上游水体中的营养盐浓度季节变化明显。蓄水期,水温(23-24℃)表底分层,浊度(20-40NTU)由河口支流上游呈梯度递减,梅溪河叶绿素a浓度高(5-6μg/L),草堂河、朱衣河叶绿素a浓度低(0.4-1μg/L);高水位运行期,水温较低(16-18℃),水体清澈(3-6NTU),三条支流中营养盐浓度表底分布均匀,不出现分层,且都与长江干流水体浓度接近。其中DIN浓度约为110μmol/L,磷酸盐浓度约为2.6μmol/L,硅酸盐浓度约为135μmol/L。叶绿素a浓度低(小于1μg/L)；泄水期,草堂河、梅溪河、朱衣河水体中叶绿素a浓度是蓄水期和高水位运行期的3-6倍,表层浓度最高可达6μg/L。水体中的DIN、磷酸盐、硅酸盐浓度表底分层明显,DIN和磷酸盐浓度比高水位运行期均有增大,硅酸盐则显著降低(下降40μmol/L左右)。且磷酸盐为全年最高值(约为5-6μmol/L),硅酸盐为全年最低值(约为80-90μmol/L);低水位运行期,草堂河、梅溪河、朱衣河水体中叶绿素a浓度达到全年最高值(约为9-12μg/L)。水体比较浑浊(约为40NTU)。DIN和硅酸盐浓度均显著增大,磷酸盐浓度显著减小 (4)低水位运行期和蓄水期河口的水体交换能力强,泄水期和高水位运行期河口的水体交换能力弱。支流河口的营养盐混合比较均匀,不会随着水体的进出而出现明显的分层现象。尽管支流河口进出的流量比较大,营养盐的交换相对较强,但是单位时间内真正进入库湾的营养盐比较少。支流库湾水体中的营养盐是长江水体持续不断地输入交换,再慢慢累积的结果。
[Abstract]:From August 2012 to July 2013, the hydrodynamic characteristics, nutrient salt, water temperature, turbidity, chlorophyll and other parameters of the three tributaries of the Three Gorges Reservoir area were observed for one year. The characteristics of the water stratification in the tributary estuary were analyzed. The quantity of the flow in the water body was estimated and the distribution characteristics of the nutrients were combined. The effects of hydrodynamic characteristics of tributaries on nutrient exchange and cycling in dry tributaries of the reservoir area are discussed.
(1) there are estuarine circulation and water stratification in the estuarine estuary of the reservoir area, mainly in the form of upper and lower stratification, left and right stratification, multi-layer inversion and so on. The river mouth water exchange is strong during the low water level operation and the estuary circulation is strong. The flow velocity of the water in the inlet and outlet estuary is more seasonal, and the flow velocity of the 5,6,7 month is greater than that of the other months. The average velocity of flow is 0.083m/s, the average flow velocity of the effluent water is 0.095m/s, the average flow velocity of the inverted water body of the Meishan river is 0.079m/s and the annual average velocity of the effluent water is 0.079m/s, and the average flow velocity of the inverted water body is 0.072m/s, and the annual average flow velocity of the effluent water body is the annual average flow rate of the three tributaries of 0.07m/s.. They are: thatched River 730.55m3/s, Mexi River 428.62m3/s, Zhu Yi River 426.75m3/s. high water level operation period, estuary inlet and outlet volume is larger.
(2) the nutrient concentration in the surface layer of the reservoir area is high, in which the average of DIN is about 129.3Lmol/L, the average of DSi is about 119.5pmol/L in the year, the average of DIP is about 3.42 mu mol/L. in the year, especially phosphate, the concentration change is in accordance with the change trend of the Three Gorges water level. The change of concentration is similar to that of the surface water of the Yangtze River. The changes of DIN and phosphate are characterized by the low concentration of water storage and high water level (DIN about 95-115 mu mol/L, phosphate about 0.4-2 mol/L), the high concentration of the discharge period and low water level (about 135-175 Mu mol/L, and about 5-6 micron mol/L of phosphate). The concentration change is exactly the opposite (the concentration of the water storage period and the high water level is 120-150 u mol/L, the discharge period and the low water level in the running period are 90-100 mu). The characteristics of the nutrient composition of the Meishan River, the Meishan River and the Zhu Yi River are similar to those of the Yangtze River, which are different from the source water.
(3) the seasonal variation of nutrient concentration in the river estuary to the upper reaches is obvious. The water temperature (23-24 degrees) is stratified at the bottom of the water storage period, and the turbidity (20-40NTU) decreases gradually from the upstream of the estuary branch. The concentration of chlorophyll a in the Meishan river is high (5-6 u g/L), the concentration of chlorophyll a in the Meishan River and the Zhu Yi River is low (0.4-1 mu g/L); the water temperature is low (16-18 degrees C) at the high water level. 3-6NTU, the concentration of nutrient concentration in the three tributaries is evenly distributed, and there is no stratification, and it is close to the water concentration in the Yangtze River. The concentration of DIN is about 110 mu mol/L, the concentration of phosphate is about 2.6 mu mol/L, the concentration of silicate is about 135 mu mol/L. and the concentration of chlorophyll a is low (less than 1 mu g/L). The concentration of chlorophyll a in the body is 3-6 times that of the water storage period and the high water level. The highest surface concentration can be up to DIN in 6 Mu water body. Phosphate, silicate concentration is obviously stratified at the bottom of the table. The concentration of DIN and phosphate is higher than the high water level, and the silicate is significantly reduced (down to about 40 mu). And phosphate is the highest value of the year (about 5-6). Mol/L), silicate is the lowest value of the year (about 80-90 mu mol/L), and the concentration of chlorophyll a in the water body of the Meishan River, Meishan River and Jishan river reaches the highest value of the year (about 9-12 mu g/L) in the low water level operation period. The water body is more turbidity (about 40NTU).DIN and silicate concentration, and the phosphate concentration is significantly reduced.
(4) the water exchange capacity of the estuaries at the low water level and the water storage period is strong, and the water exchange ability of the estuaries in the discharge period and the high water level is weak. The mixing of the nutrients in the tributary estuary is even more uniform, and it will not appear obvious stratification with the flow of water. Although the flow rate of the tributary estuary is relatively large, the exchange of nutrients is relatively strong. But the nutrient salts in the bay of the Bay are relatively small in unit time. The nutrients in the water body of the tributary Bay are the result of the continuous input and exchange of the Yangtze River water body and the accumulation of the water in the Yangtze River.

【学位授予单位】：华东师范大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TV14;X143

【参考文献】