Hydrochemistry of Rara Lake: A Ramsar lake from the southern slope of the central Himalayas,Nepal  

作　　者：KAPHLE Binija WANGJun-bo KAI Jin-lei LYU Xin-miao PAUDAYAL Khum Narayan ADHIKARI Subash 

机构地区：[1]Key Laboratory of Tibetan Environment Changes and Land Surface Processes(TEL),Institute of Tibetan Plateau Research,Chinese Academy of Sciences,Beijing 100101,China [2]CAS Center for Excellence in Tibetan Plateau Earth Sciences,Beijing 100101,China [3]University of Chinese Academy of Sciences,Beijing 100049,China [4]Central Department of Geology,Tribhuvan University,Kritipur,Kathmandu 44600,Nepal

出　　处：《Journal of Mountain Science》2021年第1期141-158,共18页山地科学学报（英文）

基　　金：financed by the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA20070101);the Second Tibetan Plateau Scientific Expedition and Research Program(STEP)(2019QZKK0202);the National Natural Science Foundation of China(41877168,and 41671214)。

摘　　要：High-altitude Himalayan lakes act as natural storage for environmental evidence related to climate change and environmental factors.A great number of lakes are distributed in the southern slope area of the central Himalayas;however,research concerning the hydrochemical processes of these lakes is still insufficient.Herein,we present a comprehensive study on the water chemistry of the lake waters and the inlet stream waters from Rara Lake in western Nepal based upon samples collected in November 2018.The p H,dissolved oxygen,chlorophyll-aconcentration(chl-a),water temperature,electric conductivity(EC)and total dissolved solids(TDS)were measured in situ,and the concentrations of major ions(Ca^(2+),Mg^(2+),K^(+),Na^(+),Cl^(-),SO_(4)^(2-),and NO_(3)^(-))were analyzed in the laboratory.The results revealed that the water in Rara Lake is slightly alkaline,with p H values ranging from 7.6-7.98.The cations,in decreasing order of concentration in the lake water,are Ca^(2+)>Mg^(2+)>K^(+)>Na^(+)with average concentrations of20.64 mg·L^(-1),11.78 mg·L^(-1),1.48 mg·L^(-1) and 0.72 mg·L^(-1),respectively;the order and concentrations for the anions is HCO_(3)^(-)>SO_(4)^(2-)>Cl^(-)>NO_(3)^(-),with average concentrations of 122.15 mg·L-1,2.15 mg·L-1,0.46mg·L-1 and 0.55 mg·L-1,respectively.The dominant cation and anion in the lake water are Ca2+and HCO3-and they account for 48.14%and 71.8%of the totals,respectively.The range of lake water TDS is from 95mg·L^(-1) to 98 mg·L^(-1),with an average of 96.85 mg·L^(-1).The high ratio of(Ca^(2+)+Mg^(2+))to total cations and the low ratio of(Na^(+)+K^(+))to total cations indicate that Rara Lake receives ions from rock weathering,especially from carbonate rocks.Similarly,Gibbs boomerang diagrams and Piper diagrams also support the hydrochemistry of Rara Lake as being dominated by rock-weathering patterns.Likewise,other statistical analysis tools,such as Principal Component Analysis(PCA)and correlation strongly suggest the dominance of weathering of calcium and magnesium bicarbon

关 键 词：Water quality profiling Major ions Rock weathering ANTHROPOGENIC Rara Lake HIMALAYAS 

分 类 号：P342[天文地球—水文科学]