漓江干流水体主要离子化学变化特征及影响因素

Chemical Characteristics Changes of Major Ion and Its Influencing Factors in the Main Stream of Lijiang River

关键词:  漓江  水化学  离子  碳酸盐岩风化  变化

Key words:  Lijiang River  hydrochemistry  ion  carbonate rocks weathering  variation

摘要:

[目的]为保护漓江流域水环境及揭示区域碳酸盐岩风化过程提供基础数据及科学支撑。[方法]通过收集一个水文年漓江干流典型断面的水样，并进行水化学分析来研究水体中离子化学变化特征及其控制因素。[结果]漓江两个断面水化学类型都为Ca-HCO₃型，河水主要离子组分受到水岩作用的控制。两个断面对比来看，上游大面圩（DM）断面受到部分降雨输入的影响，而下游普益（PY）断面受到更加强烈的碳酸盐岩风化作用的影响。漓江两个断面HCO₃^-、Ca²⁺离子浓度表现出雨季小于旱季的现象，主要受到雨季降雨和流量增大的影响，而SO₄^2-、NO₃^-、Cl^-离子浓度出现雨季大于旱季的现象，则主要受到农业活动、城市排污的影响。此外，由于人类活动的影响，漓江碳酸盐岩风化受到外源酸的影响，进而影响岩溶风化碳汇效应的评估。[结论]漓江典型断面水体优势离子（HCO₃^-、Ca²⁺）变化特征主要受到地质条件的控制，岩溶作用强度表现出显著的空间差异性；SO₄^2-、NO₃^-、Cl^-离子则受到不同人类活动的影响，表现出显著的季节变化和空间变化。

Abstract:

[Objective] To provide basic data and scientific support for protecting the water environment of the Lijiang River basin and revealing the weathering process of the regional carbonate rock.[Methods] The characteristics of ion chemical changes and their controlling factors were studied by collecting water samples from typical sections of the Lijiang River in the hydrological year and performing hydrochemistry analysis.[Results] The hydrochemistry types of two sections in the Lijiang River were all Ca-HCO₃ type,and the main ionic components of the river were controlled by water-rock interaction. In comparison of the two sections,the upstream Damianxu(DM) section was affected by partial rainfall input,and the downstream Puyi(PY) section was affected by more intense weathering of carbonate rocks. The HCO₃^- and Ca²⁺ ion concentrations in the two sections of the Minjiang River were affected by the increase of rainfall and flow in the rainy season,which made the two ions in rainy season less than that in the dry season. But due to the influence of agricultural activities and urban sewage,the SO₄^2-、NO₃^- and Cl^- ions in the rainy season in the Lijiang River was larger than that in the dry season. In addition,due to the influence of human activities,weathering of carbonate rocks in the Lijiang River was affected by exogenous acids,which might in turn affect the karst weathering carbon sinks evaluation.[Conclusion] The variation characteristics of the dominant ions (HCO₃^- and Ca²⁺) in the typical section of the Lijiang River are mainly controlled by the geological conditions,and the intensity of the karstification shows significant spatial differences; SO₄^2-、NO₃^- and Cl^- ions are influenced by different human activities,showing significant seasonal and spatial changes.