Zhao Zong-Quan, Suo Hui-Ying, Jiao Shu-Lin
School of Geography and Environmental Science, Guizhou Normal University, Guiyang 550025, China.
Key Laboratory of Remote Sensing Application on Mountain Resources and Environment in Guizhou Pro-vince, Guiyang 550025, China.
Ying Yong Sheng Tai Xue Bao. 2020 Jun;31(6):1783-1790. doi: 10.13287/j.1001-9332.202006.028.
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 δC 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 (NO-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 (pCO) and DIC appeared during the summer high flow phase. On the water column in summer, redox potential (Eh) and NO-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 pCO showed an opposite trend. Water EC, total alkalinity (TA), and DIC decreased with increa-sing 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 pCO in both seasons. 2) The concentration of DIC was 2.66-4.9 mmol·L in summer and 3.38-4.52 mmol·L in winter. During the period of thermal stratification, the variation gradients of DIC and δC in the thermocline were most significant. DIC was positively correlated with δC of epilimnion in summer. DIC was negatively correlated with δC in epilimnion in winter and on water column in both summer and winter. However, the variation of DIC and δC with water depth was not obvious in winter. 3) In summer, δC was -7.71‰- -1.38‰, indicating that the dissolution of carbonate minerals was dominant. In winter, δC was -16.93‰- -9.44‰, signifi-cantly lower than that in summer but with a wider range, indicating biological input of CO and mineralization of organic matter were the main sources. The δC varied significantly in different seasons and water depths because of differences in carbon sources and changes in the relative contribution proportion of carbon sources.
溶解无机碳（DIC）作为碳收支的重要组成部分，其通量和形态在水生生态系统的生物地球化学过程中起着关键作用。通过分析万峰湖水库的理化参数以及水体DIC和δC特征，我们研究了DIC的行为和来源。在表水层，整个水库水体的pH呈保守状态，为弱碱性。硝酸盐（NO₃-N）的变异系数最大，具有较高的时空变异性。由于稀释效应，电导率（EC）、二氧化碳分压（pCO₂）和DIC的最低值出现在夏季高流量期。夏季水柱中，氧化还原电位（Eh）和NO₃-N不随水深变化，而其他指标变化显著，在温跃层变化最大。水温（T）、pH和Eh在两个季节均随水深增加而降低，而pCO₂呈现相反趋势。夏季水体EC、总碱度（TA）和DIC随水深增加而降低，但冬季变化梯度较小。两个季节水体中的DIC均与水体pH和Eh呈负相关，与EC和pCO₂呈正相关。2）夏季DIC浓度为2.66 - 4.9 mmol·L⁻¹，冬季为3.38 - 4.52 mmol·L⁻¹。在热力分层期间，温跃层中DIC和δC的变化梯度最为显著。夏季DIC与表水层的δC呈正相关。冬季DIC与表水层的δC以及夏季和冬季水柱中的δC均呈负相关。然而，冬季DIC和δC随水深的变化不明显。3）夏季，δC为-7.71‰ - -1.38‰，表明碳酸盐矿物的溶解占主导。冬季，δC为-16.93‰ - -9.44‰，明显低于夏季但范围更广，表明CO₂的生物输入和有机质矿化是主要来源。由于碳源不同以及碳源相对贡献比例的变化，δC在不同季节和水深存在显著差异。
