武夷山国家公园水化学时空分布特征及控制因素

Temporal and Spatial Distributions and Controlling Factors of Hydrochemistry at Wuyishan National Park Water Body

【目的】分析武夷山国家公园九曲溪水体主要阴、阳离子的含量变化,揭示该区域地表水水化学时空分布特征、作用机制和岩性控制类型。【方法】采集不同水文期及河流段的30份地表水样品,测试主要化学离子组分含量,利用吉布斯图、三角图和端元图进行水化学的作用机制和岩性类型分析,并以主成因分析和模型计算量化水化学物质的来源贡献。【结果】九曲溪水体呈弱酸性,总溶解固体(TDS)的平均值为25.30 mg·L^(-1)(远低于世界河流的平均值100.00 mg·L^(-1)),主要阳离子含量的大小顺序为Ca^(2+)>Na^(+)>K^(+)>Mg^(2+),主要阴离子含量HCO^(-)_(3)>Cl^(-)>NO^(-)_(3)>SO^(2-)_(4)。不同水文期对比而言,该流域水体TDS及大多数主要离子浓度呈现出枯水期>平水期>丰水期;不同河流段对比,TDS及主要离子浓度从上游到下游整体呈现上升趋势。【结论】武夷山国家公园九曲溪水化学类型为HCO^(-)_(3)-Ca^(2+)+Na^(+)型,作用机制以岩石风化为主,一定程度受大气降水和人为活动的影响。其中,岩石风化对上游河段的水化学组成影响小于中下游;大气降水对丰水期的水化学作用大于其他水文期。同时,研究区水化学的岩性控制类型以碳酸岩和硅酸岩的风化作用为主,两者对水化学物质的贡献率为58.82%。

【Objective】Contents of major anions and cations in the Jiuquxi River at the Wuyishan National Park were analyzed to unveil the spatial and temporal distributions,action mechanism,and lithological control of the surface water.【Method】Thirty water samples from different river sections were collected at different hydrological periods for chemical determination.Gibbs,triangle,and endmember diagrams were applied to analyze the hydrochemical mechanism and lithological control.Principal component analysis and model calculation were applied to quantify the hydrochemical contributions.【Result】The river water was weakly acidic with an average total dissolved solids(TDS)of 25.30 mg·L^(-1),which was well below the world average of 100.00 mg·L^(-1).The contents of major cations in the water ranked in the order of Ca^(2+)>Na^(+)>K^(+)>Mg^(2+),while that of anions HCO^(-)_(3)>Cl^(-)>NO^(-)_(3)>SO^(2-)_(4).In different hydrological periods,TDS and most of the ions were dry period>normal period>wet period and increased from upstream to downstream of the river.【Conclusion】The hydrochemistry of Jiuquxi water in the national park was HCO^(-)_(3)-Ca^(2+)+Na^(+)type and,basically,of a rock weathering action mechanism that affected by precipitation,and to a certain extent,human activities.The rock weathering altered the hydrochemistry more on the upper reach than the middle or lower reach of the river.Precipitation affected the hydrochemistry most greatly in wet season.The lithological control on the area waters was largely weathering of carbonate and silicate rocks that contributed 58.82%of the controlling factors of the hydrochemistry.