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| 2019-2023年向家坝水库叶绿素a时空分布特征及其与环境因子的关系 |
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刘芳枝, 赵明亮, 黄宇波, 潘增, 张勇, 周凌
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中国长江三峡集团有限公司流域枢纽运行管理中心
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| 摘要: |
| 基于2019—2023年金沙江向家坝水库干、支流20个断面的叶绿素a（Chl.a）及相关环境因子的月度数据，运用数理统计、相关性分析、逐步回归、通径分析等方法，探究了向家坝水库Chl.a的时空分布特征及其与环境因子的关系。研究表明，向家坝水库Chl.a 5年平均浓度为3.91 μg/L，年际间Chl.a浓度呈波动变化但无明显规律，季节方面，春、夏、秋三季Chl.a浓度均显著高于冬季；空间分布上，支流库湾Chl.a浓度高于干流，干流年均Chl.a浓度沿程呈现上升趋势，且干流坝前江段Chl.a浓度高于坝后江段，支流库湾人口相对集中的断面Chl.a年均浓度较高。Pearson相关分析、逐步回归分析、通径分析结果均表明，不同年份、不同季节、不同断面影响Chl.a浓度的环境因子不尽相同，存在时间及空间差异。Pearson相关分析表明，研究期间向家坝水库全库Chl.a与总磷（TP）、正磷酸盐（PO43--P）、氨氮（NH3-N）、硝态氮（NO3--N）、总氮（TN）、高锰酸盐指数（CODMn）、气温（T）、水温（WT）、溶解氧（DO）、pH呈正相关，与透明度（SD）、电导率（Cond）、水速（V）呈显著负相关。逐步回归分析筛选出对库区整体Chl.a浓度影响显著的8个环境因子分别为TN、PO43--P、TP、pH、DO、CODMn、SD、T，除SD与Chl.a浓度呈极显著负相关外，其余环境因子均与Chl.a浓度呈正相关；而通径分析决策系数则表明CODMn、TN、SD是影响向家坝水库Chl.a浓度最主要的环境因子。分析表明，pH、DO、CODMn、SD为影响向家坝水库Chl.a浓度的被动因子，TN、PO43--P、TP等营养盐为限制性因子，温度则为关键因子。本研究对掌握向家坝水库浮游植物生长情况、了解其水体营养状态具有重要意义，同时也可为金沙江下游巨型梯级水库水环境研究提供一定的参考依据。 |
| 关键词: 向家坝水库 叶绿素a 逐步回归分析 通径分析 |
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| 基金项目:中国长江三峡集团有限公司技术服务项目（0711541、0711556、0711572）、中国长江三峡集团有限公司自主科研项目（NBYG202200449、NBYG202200579） |
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| Spatiotemporal characteristics of chlorophyll-a and its influencing factors in Xiangjiaba Reservoir from 2019 to 2023 |
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Liu Fangzhi, Zhao Mingliang, Huang Yubo, Pan Zeng, Zhang Yong, Zhou Ling
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River Basin Complex Administration Center,China Three Gorges Corporation
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| Abstract: |
| Spatio-temporal characteristics of chlorophyll-a(Chl.a) concentration and its influencing factors in Xiangjiaba Reservoir，Jinsha River during 2019-2023 were investigated using mathematical statistics, correlation analysis, stepwise regression and path analysis. The results showed that the annual average of Chl.a in Xiangjiaba Reservoir was 3.91 μg/L, and the annual variation of Chl.a was irregular. According to seasons, Chl.a was significantly higher in spring, summer and autumn than in winter. The Chl.a in the tributary was higher than that in the main stream. The annual average Chl.a increased gradually from the upstream to the downstream of the main stream. The section with more population in the tributary had higher Chl.a. Pearson correlation analysis, stepwise regression analysis and path analysis showed that there were spatio-temporal variations in environmental factors affecting Chl.a in different years, seasons and sections. Pearson correlation analysis showed that Chl.a was significantly positively correlated with total phosphorus（TP）, orthophosphate（PO43--P）, ammonia nitrogen（NH3-N）, nitrate nitrogen（NO3--N）, total nitrogen（TN）, permanganate index（CODMn）, air temperature（T）, water temperature（WT）, dissolved oxygen（DO）, pH, and significantly negatively correlated with SD, Cond and V. Stepwise regression analysis showed that eight environmental factors (i.e., TN, PO43--P, TP, pH, DO, CODMn, SD and T) had significant impacts on Chl.a in the reservoir area. These environmental factors were positively correlated with Chl.a except SD. The path analysis decision coefficient showed that CODMn, TN and SD were the most important environmental factors affecting Chl.a. The final analysis showed that pH, DO, CODMn and SD were the passive factors affecting Chl.a, while TN, PO43--P, TP and other nutrients were the limiting factors, and temperature was the key factor. These results can improve our understanding of phytoplankton growth and nutrient status, and can provide a reference for studying the water environment of the Jinsha River cascade reservoirs. |
| Key words: Xiangjiaba Reservoir Chlorophyll-a Stepwise regression analysis Path analysis |
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