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Correlation matrix (Table 2) and factor analysis (Table 3) add further insights to these results as they identify other processes in addition to carbonate weathering which are regulating the meltwater chemistry of the upper Ganglass catchment. The strong correlation between Ca, Mg, K, HCO3 and EC with each other during the early melt period indicates the role of ion exchange process as well. Most of the catchment experiences seasonal freezing in winter with very low winter temperatures up to −27.4 °C. Hence, meltwater infiltrations to the surface soil also help in seasonal thawing and enhance the residence time of snow meltwater in the catchment, which help it to acquire more ions. The significant negative correlation of SO4 with EC, cations and HCO3 suggests inputs from multiple sources (Khadka & Ramanathan 2013). Atmospheric deposition of SO4 from burning of coal and oil for winter-time heating might be the other possible source. During the peak melt period, all the major cations were showing significant correlation with each other suggesting input from combined carbonate/silicate weathering and ion exchange process (Oinam et al. 2012). Significant correlation of silica with all major cations and HCO3 indicates weathering of aluminosilicate minerals (Singh et al. 2011). The correlation matrix shows the dominance of carbonate weathering during the late melt period. In the factor analysis, the early melt period explains 76% of the total variance with four major factors showing an eigen value >1. Factor 1 with very high loading (>0.8) of K, Ca, Mg, HCO3 and EC explains about 43% of variance indicating carbonate weathering followed by ion exchange processes. Factor 2 (12% of variance) shows high loading of silica and PO4 indicating silicate weathering along with phosphorite leaching or anthropogenic contribution (Singh et al. 2014). Factor 3 (10.6% variance) with high loading of Na and Cl suggests deposition of sea salt aerosol. For the peak melt period, a total of three factors explaining 68% of the total variance have been identified. Factor 1 (47.5% variance) has high loading of Na, K, Ca, Mg, silica, Cl, HCO3 and EC explaining carbonate and silicate weathering along with some atmospheric deposition. Factor 2 (11.3% variance) with high loading of NO3 and pH shows atmospheric deposition (Singh et al. 2014), while factor 3 (9.4%) with high loading of PO4 and SO4 shows an anthropogenic contribution (Anshumali & Ramanathan 2007). The late melt period identifies four factors explaining 66% of the total variance. Factor 1 (33% of variance) shows high loading of Na, Ca, Mg, HCO3 and EC indicating the contribution from carbonate weathering and ion exchange process. Factor 2 (13% of variance) with high loading of Na, silica and SO4 suggests sulphide oxidation coupled with silicate weathering. Factor 3 (10.9% of variance) with a high loading of K and silica indicates silicate weathering. Factor 4 (9% of variance) with a strong loading of PO4 and Cl shows the anthropogenic and atmospheric contribution. Thus, the overall factors for the melt period can be grouped as carbonate and silicate weathering, ion exchange process and atmospheric deposition (alkaline dust, anthropogenic pollutants and sea salt aerosol). The atmospheric deposition can be linked to significant snow fall (which persisted until June 22, 2010) observed in the basin causing a higher accumulation of snow.

Table 2

Correlation matrix of measured parameters for the upper Ganglass catchment during early melt period, peak melt period and late melt period of 2010

 ECpHNaKCaMgH4SiO4PO4SO4NO3ClHCO3
Early melt period 
 EC 1.00            
 pH 0.07 1.00           
 Na 0.02 −0.01 1.00          
 K 0.75** 0.13 0.17 1.00         
 Ca 0.98** 0.04 −0.09 0.73** 1.00        
 Mg 0.95** 0.06 0.31* 0.75** 0.90** 1.00       
 H4SiO4 0.37** 0.06 0.01 0.07 0.36* 0.39** 1.00      
 PO4 0.23 −0.12 0.24 0.20 0.14 0.30* 0.28 1.00     
 SO4 − 0.62** 0.19 0.22 − 0.51** − 0.65** − 0.51** −0.12 −0.04 1.00    
 NO3 0.26 −0.12 −0.04 0.22 0.28 0.23 0.18 0.08 −0.38* 1.00   
 Cl 0.16 −0.21 0.19 0.09 0.17 0.24 0.04 −0.15 0.01 −0.11 1.00  
 HCO3 0.91** 0.00 −0.02 0.70** 0.88** 0.84** 0.36* 0.27 − 0.66** 0.32* 0.04 1.00 
Peak melt period 
 EC 1.00            
 pH −0.08 1.00           
 Na 0.75** −0.11 1.00          
 K 0.61** −0.02 0.49** 1.00         
 Ca 0.93** −0.10 0.63** 0.50** 1.00        
 Mg 0.93** −0.23 0.73** 0.55** 0.87** 1.00       
 H4SiO4 0.76** −0.02 0.60** 0.50** 0.65** 0.77** 1.00      
 PO4 −0.28* 0.10 −0.13 −0.02 −0.38** −0.36** −0.20 1.00     
 SO4 0.12 0.02 0.17 0.09 0.14 0.06 0.03 0.04 1.00    
 NO3 0.07 0.27* −0.06 0.01 0.13 −0.01 −0.09 0.06 0.01 1.00   
 Cl 0.51** 0.07 0.39** 0.18 0.48** 0.50** 0.39** −0.23 0.04 0.16 1.00  
 HCO3 0.91** −0.11 0.63** 0.59** 0.90** 0.85** 0.64** −0.33** 0.18 0.02 0.47** 1.00 
Late melt period 
 EC 1.00            
 pH 0.33 1.00           
 Na 0.53** −0.01 1.00          
 K 0.12 0.01 0.17 1.00         
 Ca 0.99** 0.33 0.50** 0.11 1.00        
 Mg 0.55** 0.02 0.35* 0.14 0.52** 1.00       
 H4SiO4 0.19 −0.03 0.35* 0.21 0.17 0.16 1.00      
 PO4 −0.08 0.07 −0.13 0.01 −0.09 −0.06 0.00 1.00     
 SO4 0.04 −0.19 0.31 −0.01 0.04 0.16 0.19 0.02 1.00    
 NO3 −0.03 −0.14 −0.01 −0.13 −0.02 −0.26 −0.02 −0.08 0.24 1.00   
 Cl 0.31 0.07 0.06 0.01 0.32 0.15 0.08 0.08 0.01 0.09 1.00  
 HCO3 0.99** 0.34 0.47** 0.12 0.99** 0.54* 0.13 −0.11 0.01 0.02 0.32 1.00 
 ECpHNaKCaMgH4SiO4PO4SO4NO3ClHCO3
Early melt period 
 EC 1.00            
 pH 0.07 1.00           
 Na 0.02 −0.01 1.00          
 K 0.75** 0.13 0.17 1.00         
 Ca 0.98** 0.04 −0.09 0.73** 1.00        
 Mg 0.95** 0.06 0.31* 0.75** 0.90** 1.00       
 H4SiO4 0.37** 0.06 0.01 0.07 0.36* 0.39** 1.00      
 PO4 0.23 −0.12 0.24 0.20 0.14 0.30* 0.28 1.00     
 SO4 − 0.62** 0.19 0.22 − 0.51** − 0.65** − 0.51** −0.12 −0.04 1.00    
 NO3 0.26 −0.12 −0.04 0.22 0.28 0.23 0.18 0.08 −0.38* 1.00   
 Cl 0.16 −0.21 0.19 0.09 0.17 0.24 0.04 −0.15 0.01 −0.11 1.00  
 HCO3 0.91** 0.00 −0.02 0.70** 0.88** 0.84** 0.36* 0.27 − 0.66** 0.32* 0.04 1.00 
Peak melt period 
 EC 1.00            
 pH −0.08 1.00           
 Na 0.75** −0.11 1.00          
 K 0.61** −0.02 0.49** 1.00         
 Ca 0.93** −0.10 0.63** 0.50** 1.00        
 Mg 0.93** −0.23 0.73** 0.55** 0.87** 1.00       
 H4SiO4 0.76** −0.02 0.60** 0.50** 0.65** 0.77** 1.00      
 PO4 −0.28* 0.10 −0.13 −0.02 −0.38** −0.36** −0.20 1.00     
 SO4 0.12 0.02 0.17 0.09 0.14 0.06 0.03 0.04 1.00    
 NO3 0.07 0.27* −0.06 0.01 0.13 −0.01 −0.09 0.06 0.01 1.00   
 Cl 0.51** 0.07 0.39** 0.18 0.48** 0.50** 0.39** −0.23 0.04 0.16 1.00  
 HCO3 0.91** −0.11 0.63** 0.59** 0.90** 0.85** 0.64** −0.33** 0.18 0.02 0.47** 1.00 
Late melt period 
 EC 1.00            
 pH 0.33 1.00           
 Na 0.53** −0.01 1.00          
 K 0.12 0.01 0.17 1.00         
 Ca 0.99** 0.33 0.50** 0.11 1.00        
 Mg 0.55** 0.02 0.35* 0.14 0.52** 1.00       
 H4SiO4 0.19 −0.03 0.35* 0.21 0.17 0.16 1.00      
 PO4 −0.08 0.07 −0.13 0.01 −0.09 −0.06 0.00 1.00     
 SO4 0.04 −0.19 0.31 −0.01 0.04 0.16 0.19 0.02 1.00    
 NO3 −0.03 −0.14 −0.01 −0.13 −0.02 −0.26 −0.02 −0.08 0.24 1.00   
 Cl 0.31 0.07 0.06 0.01 0.32 0.15 0.08 0.08 0.01 0.09 1.00  
 HCO3 0.99** 0.34 0.47** 0.12 0.99** 0.54* 0.13 −0.11 0.01 0.02 0.32 1.00 

**Correlation is significant at the 0.01 level.

*Correlation is significant at the 0.05 level.

Table 3

Factor analysis of meltwater from the upper Ganglass catchment for the melt periods of 2010

 Early melt period
Peak melt period
Late melt period
VariablesFactor 1Factor 2Factor 3Factor 4CommunalitiesFactor 1Factor 2Factor 3CommunalitiesFactor 1Factor 2Factor 3Factor 4Communalities
EC 0.97 0.16 0.01 0.01 0.96 0.98 0.04 −0.03 0.95 0.98 0.01 0.05 0.06 0.97 
pH 0.10 −0.04 −0.07 0.93 0.87 −0.11 0.74 0.16 0.59 0.38 −0.53 0.04 0.20 0.47 
Na 0.00 0.37 0.76 0.03 0.71 0.80 −0.10 0.16 0.67 0.55 0.51 0.21 −0.18 0.64 
0.82 0.08 0.10 0.10 0.70 0.67 −0.03 0.34 0.56 0.09 0.16 0.62 0.07 0.42 
Ca 0.97 0.07 −0.07 −0.03 0.94 0.92 0.07 −0.15 0.87 0.98 −0.01 0.02 0.06 0.96 
Mg 0.91 0.26 0.25 0.01 0.97 0.94 −0.10 −0.15 0.92 0.59 0.14 0.37 −0.09 0.51 
H4SiO4 0.29 0.54 −0.06 0.02 0.38 0.80 −0.06 0.00 0.64 0.17 0.54 0.40 0.13 0.49 
PO4 0.09 0.84 0.12 −0.09 0.74 −0.31 0.09 0.73 0.63 −0.18 −0.03 0.18 0.83 0.75 
SO4 − 0.70 0.06 0.39 0.34 0.76 0.19 0.03 0.57 0.37 0.05 0.76 −0.13 0.05 0.60 
NO3 0.27 0.28 −0.43 −0.37 0.47 0.03 0.80 −0.05 0.64 0.01 0.38 −0.74 0.08 0.70 
Cl 0.23 −0.38 0.66 −0.35 0.75 0.55 0.34 −0.30 0.51 0.37 0.04 −0.22 0.57 0.51 
HCO3 0.90 0.23 −0.12 −0.07 0.89 0.92 0.01 −0.05 0.85 0.98 −0.04 0.01 0.04 0.96 
Eigen value 5.16 1.48 1.27 1.22  5.70 1.36 1.13  3.99 1.60 1.31 1.09  
% of variance 43.01 12.34 10.60 10.13  47.51 11.33 9.44  33.28 13.32 10.92 9.12  
% of cumulative variance 43.01 55.35 65.95 76.08  47.51 58.84 68.28  33.28 46.60 57.52 66.63  
 Early melt period
Peak melt period
Late melt period
VariablesFactor 1Factor 2Factor 3Factor 4CommunalitiesFactor 1Factor 2Factor 3CommunalitiesFactor 1Factor 2Factor 3Factor 4Communalities
EC 0.97 0.16 0.01 0.01 0.96 0.98 0.04 −0.03 0.95 0.98 0.01 0.05 0.06 0.97 
pH 0.10 −0.04 −0.07 0.93 0.87 −0.11 0.74 0.16 0.59 0.38 −0.53 0.04 0.20 0.47 
Na 0.00 0.37 0.76 0.03 0.71 0.80 −0.10 0.16 0.67 0.55 0.51 0.21 −0.18 0.64 
0.82 0.08 0.10 0.10 0.70 0.67 −0.03 0.34 0.56 0.09 0.16 0.62 0.07 0.42 
Ca 0.97 0.07 −0.07 −0.03 0.94 0.92 0.07 −0.15 0.87 0.98 −0.01 0.02 0.06 0.96 
Mg 0.91 0.26 0.25 0.01 0.97 0.94 −0.10 −0.15 0.92 0.59 0.14 0.37 −0.09 0.51 
H4SiO4 0.29 0.54 −0.06 0.02 0.38 0.80 −0.06 0.00 0.64 0.17 0.54 0.40 0.13 0.49 
PO4 0.09 0.84 0.12 −0.09 0.74 −0.31 0.09 0.73 0.63 −0.18 −0.03 0.18 0.83 0.75 
SO4 − 0.70 0.06 0.39 0.34 0.76 0.19 0.03 0.57 0.37 0.05 0.76 −0.13 0.05 0.60 
NO3 0.27 0.28 −0.43 −0.37 0.47 0.03 0.80 −0.05 0.64 0.01 0.38 −0.74 0.08 0.70 
Cl 0.23 −0.38 0.66 −0.35 0.75 0.55 0.34 −0.30 0.51 0.37 0.04 −0.22 0.57 0.51 
HCO3 0.90 0.23 −0.12 −0.07 0.89 0.92 0.01 −0.05 0.85 0.98 −0.04 0.01 0.04 0.96 
Eigen value 5.16 1.48 1.27 1.22  5.70 1.36 1.13  3.99 1.60 1.31 1.09  
% of variance 43.01 12.34 10.60 10.13  47.51 11.33 9.44  33.28 13.32 10.92 9.12  
% of cumulative variance 43.01 55.35 65.95 76.08  47.51 58.84 68.28  33.28 46.60 57.52 66.63  

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