摘要:
利用多参数水质分析仪,对典型岩溶槽谷区重庆青木关岩溶地下河出口姜家泉的月尺度、农耕期和暴雨期3个不同时间段的水化学动态变化特征进行监测,通过主成分分析法,研究这3个不同时间段水化学变化主导因素的异同。结果表明:月尺度期间,电导率、pH 值和 Ca2+、Mg2+、K+、Na+、HCO -3受雨水稀释作用,使丰水期低于枯水期;水化学变化主要受5个主成分影响,累积方差贡献率为90.75%,但其主导因素是水-岩作用。农耕期,降雨携带残余的粪肥、氮磷钾肥汇入地下河,电导率和 Cl-、NO -3、K+、Na+浓度升高;水化学变化主要受3个主成分影响,累积方差贡献率为87.81%,但其主导因素是施肥活动。暴雨期间,各离子浓度变化经过平稳期、上升期、稳定期、特殊期4个阶段。上升期,降雨对地下河影响最大,导致水-岩作用增强,电导率和 Ca2+、HCO -3浓度上升;对地表土壤和化肥的冲刷淋溶作用显著,导致 Al、Fe、Cl-、K+、Na+和 NO -3浓度明显上升。水化学变化主要受4个主成分影响,累积方差贡献率为80.09%,但其主导因素是水-岩作用、地表土壤和养分流失。
Abstract:
Hydrochemical variation of Qingmuguan karst underground river in the typical karst valley area was monitored by using multi-parameter water quality analyzer.Dominant factors of the chemical dynamics were studied by principal component analysis method with monitoring data derived from three different time intervals,including that of monthly monitoring,storm event and farming period.Results showed that on a monthly scale,because of the dilution effect due to rainfall,the major underground river constituents such as pH and the concentrations of Ca2 + ,Mg2 + ,K+ ,Na+ and HCO -3 were lower at flooding or wet season than those of dry season.The hydrochemical variation was affected by five main components with an accumulated variance contribution rate of 90.75%,of which the dominant factor was identified as the rock-water interac-tion.In farming period,rainwater carried residual manure and nitrogenous,phosphate and potash fertilizers into the underground river,which resulted in the increase of electrical conductivity (EC)and Cl- ,NO -3 ,K+and Na+ contents.The hydrochemical variation was affected by three main components,with an accumula-ted variance contribution rate of 87.81%,of which the dominant factors were rock-water interaction and fer-tilization.During the storm event,the change of the ionic concentrations could be divided into four stages, including stationary,rising,stable and special periods.During the rising period,rainfall obviously effected on underground river and caused more active rock-water interaction and the increases of EC and the concen-trations of Ca2 + and HCO -3 .Significant impact of erosion and leaching due to rainfall on topsoil and fertiliz-ers resulted in obvious raises in undergroundriver Al,Fe,Cl- ,K+ ,Na+ and NO -3 contents.The hydro-chemical variation was affected by four main components with an accumulated variance contribution rate of 80.09%;and the dominant factors could be rock-water interaction,soil erosion and soil nutrient leaching.
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