喀斯特水库水化学特征及对无机碳沉积通量的指示  

Hydrochemical characteristics in karst reservoirs and its implication for inorganic carbon deposition fluxes

作　　者：马松 魏榆 韩翠红 晏浩 刘再华[1] 孙海龙 鲍乾 Ma Song;Wei Yu;Han Cuihong;Yan Hao;Liu Zaihua;Sun Hailong;Bao Qian(State Key Laboratory of Environmental Geochemistry,Institute of Geochemistry,Chinese Academy of Sciences,Guiyang 550002,P.R.China;University of Chinese Academy of Sciences,Beijing 100049,P.R.China)

机构地区：[1]中国科学院地球化学研究所环境地球化学国家重点实验室,贵阳550002 [2]中国科学院大学,北京100049

出　　处：《湖泊科学》2021年第6期1701-1713,共13页Journal of Lake Sciences

基　　金：国家自然科学基金委员会-贵州喀斯特科学研究中心联合基金重大项目(U1612441);国家自然科学基金项目(41673019,41977298)联合资助.

摘　　要：为探究筑坝后不同水库物理、化学、生物过程对水化学和碳循环的影响,本研究对贵州三岔河流域的平寨水库、普定水库以及猫跳河流域的红枫湖水库进行研究,于2018年3月2019年1月分别在入库河流和库区采集了分层水样和沉降颗粒物,并探究水中主要离子及颗粒物通量的时空变化特征及其控制因素.结果表明,水体主要离子的主要来源受碳酸盐溶解影响,并且离子浓度受光合作用控制.红枫湖水库水体水化学类型为Ca-Mg-HCO_(3)-SO_(4)型,普定水库、平寨水库水化学类型均为Ca-HCO_(3)-SO_(4).夏季藻类光合作用诱导碳酸盐沉淀导致水体表层Ca^(2+)、HCO^(-)_(3)及溶解态Si浓度降低,其降低幅度分别为20.87%~44.25%、33.12%~51.18%、48.55%~96.34%.此外,藻类光合作用也影响C、N、Si等生源要素间的化学计量关系.Mg^(2+)/Ca^(2+)比值在水体垂向剖面上主要受碳酸钙沉淀的控制,而在不同水库之间则主要受流域岩性的控制.根据沉积物捕获器通量计算的平寨水库、普定水库、红枫湖水库夏季颗粒无机碳沉积通量分别为0.74、1.36、0.27 t/(km^(2)·d),而根据水体Ca^(2+)浓度降低计算的通量分别为0.31~0.64、0.35~0.99、0.09~0.29 t/(km^(2)·d),根据水体HCO^(-)_(3)浓度降低计算的通量分别为0.30~0.65、0.29~1.26、0.12~0.33 t/(km^(2)·d).其红枫湖水库无机碳沉降通量的实测值与计算值接近,而平寨、普定水库实际沉降通量高于计算值,这可能是有外源输入导致.因此,利用水化学分层数据能对喀斯特水库中的无机碳沉降通量进行合理估算,并且能够得到较好的估算结果,从而指示碳循环的过程.To explore the impact of changes in physical, chemical and biological processes on hydrochemistry and carbon cyclecaused by damming, we investigated the flux of suspended particulate and the spatiotemporal variations of major cations and anions(Ca2+, Mg2+, Na+, K+, HCO3-, SO42-, Cl-) in three karst reservoirs in Guizhou Province, i.e. Puding Reservoir, Pingzhai Res-ervoir, and Lake Hongfeng, for a whole hydrological year. The results showed that carbonate weathering and algae photosynthesiscontrolled the spatiotemporal variations of ion concentrations. The hydro-chemical type of Lake Hongfeng is Ca-Mg-HCO3-SO4,while it is Ca-HCO3-SO4 in Puding Reservoir and Pingzhai Reservoir. During the summer period, as the result of carbonate precipitation induced by algae photosynthesis, the concentrations of Ca2+, HCO3-, and SiO2 in the surface water decreased by 20.87%-44.25%, 33.12%-51.18%, and 48.55%-96.34%, respectively. Our results also indicated that the stoichiometric relationships a-mong C, N, Si could be affected by photosynthesis of aquatic photosynthetic organisms. Additionally, it is found that calcite pre-cipitation regulated the Mg2+/Ca2+in water column. Finally, the inorganic carbon fluxes in summer period calculated by sediment traps were 0.74 t/( km2·d), 1.36 t/( km2·d), 0.27 t/( km2·d) for Pingzhai Reservoir, Puding Reservoir and respectively,which are comparable with the fluxes estimated by the concentration differences in Ca2+and HCO-3 between surface and bottom wa-ter layers. The measured fluxes of inorganic carbon in Pingzhai Reservoir and Puding Reservoir by sediment traps are higher thanthe calculated one, suggesting a certain amount of allochthonous inorganic carbon input due to the strong hydrological condition.Therefore, it is an alternative way to estimate the deposition flux of inorganic carbon in karst reservoirs by using vertical variationsin ion concentrations in stratification period.

关 键 词：水化学 喀斯特梯级水库 碳酸钙沉淀 碳循环 平寨水库 普定水库 红枫湖水库 

分 类 号：X524[环境科学与工程—环境工程]