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- Title
万峰湖水库溶解性无机磯来源及时空变异特征.
- Authors
赵宗权; 索惠英; 焦树林
- Abstract
溶解性无机碳(DIC) 的通量和形式在水生态系统的生物地球化学循环中起关键作 用,是碳收支的重要组成部分。通过分析万峰湖水库库区水体理化参数、DIC 和稳定碳同位 素(δ13CDIC)特征,揭示了DIC 的行为和来源。结果表明: 1)在表水层,整个库区pH 变化较保 守,均呈弱碱性。硝酸盐氮(NO3--⁃N)有最大变异系数,具有高度的时空变异性。由于稀释效 应的存在,电导率(EC)、二氧化碳分压(pCO2)和DIC 的最低值均出现在夏季高径流量阶段。 在水柱面上,夏季氧化还原电位(Eh) 和NO3-⁃N 随水深增加无显著变化,其余指标均变化明 显,且在温跃层变异程度最大。两季节的水温(T)、pH 和Eh 均随水深增加而降低,pCO2则与 之相反。EC、总碱度(TA) 和DIC 在夏季随水深增加而降低,冬季变化梯度较小。两季节的 DIC 与pH、Eh 呈负相关,与EC、pCO2呈正相关。2)夏季DIC 为2.66~4.9 mmol·L-1,而冬季 为3.38~4.52 mmol·L-1。水体热分层期间,DIC 和δ13 CDIC 在温跃层的变化梯度最大,DIC 与 δ13CDIC在夏季表水层呈正相关。两个季节水柱面上及冬季表水层的DIC 和δ13CDIC 均呈负相 关,但冬季DIC 和δ13 CDIC 值随水深变化趋势不明显。3) 夏季δ13 CDIC 较高, 为-7.71‰ ~ -1.38‰,表明碳酸盐矿物的溶解占优势。冬季δ13CDIC为-16.93‰~-9.44‰,显著低于夏季且 范围更宽,生物源CO2的输入和有机质矿化是主要来源。δ13CDIC在不同季节和水深均差异显 著,一方面是碳的来源不同;另一方面归因于碳来源的相对贡献比例的变化. The flux and form of dissolved inorganic carbon (DIC), an important part of carbon budget, play a key role in the biogeochemistry of aquatic ecosystem. By analyzing physicochemical parameters and water DIC and Δ³CDIC characteristics in Wanfenghu Reservoir, we examined the behavior and source of DIC. In the epilimnion, water pH in the entire reservoir was conservative, being weakly alkaline. nitrate (NO3--N) had the maximum coefficient of variation and a high spatio- temporal variation. Due to the dilution effect, the lowest values of electrical conductivity (EC), partial pressure of carbon dioxide (pCO2) and DIC appeared during the summer high flow phase. On the water column in summer, redox potential (Eh) and NO3--n did not change with water depth, while other indicators changed significantly, with greatest variation in the thermocline. Water temperature (T), pH and Eh all decreased with increasing water depth in both seasons, while pCO2 showed an opposite trend. Water EC, total alkalinity (TA), and DIC decreased with increasing water depth in summer, but with a smaller gradient of change in winter. The DIC in water was negatively correlated with water pH and Eh, while positively correlated with EC and pCO2 in both seasons. 2) The concentration of DIC was 2.66-4.9 mmol • L-1 in summer and 3.38-4.52 mmol •L-1 in winter. During the period of thermal stratilication, the variation gradients of DIC and Δ³CDIC in the thermoeline were most significant. DIC was positively correlated with δ³CDIC of epilimnion in summer. DIC was negatively correlated with Si3Cdic in epilimnion in winter and on water column in both summer and winter. However, the variation of DIC and δ³CDIC with water depth was not obvious in winter. 3) In summer, δ³CDIC was -7.71%- -1.38%, indicating that the dissolution ol'carbonate minerals was dominant. In winter, δ³CDIC was -16.93%- -9.44%, signili-cantly lower than that in summer but with a wider range, indicating biological input of CO2 and mineralization of organic matter were the main sources. The δ³CDIC varied signilicantly in different seasons and water depths because of dillerences in carbon sources and changes in the relative contribution proportiona of carbon sources.
- Subjects
CARBON isotopes; PARTIAL pressure; STABLE isotopes; RESERVOIRS; CARBON
- Publication
Yingyong Shengtai Xuebao, 2020, Vol 31, Issue 6, p1783
- ISSN
1001-9332
- Publication type
Article
- DOI
10.13287/j.1001-9332.202006.028