Appendixdprocedure for Estimation of Contribution from Different End-Members and Chemical

AppendixDProcedure for estimation of contribution from different end-members and chemical budget.

In this study, because the chemicalcharacteristics of end-members are described by molar ratios, all the hydrochemistry data of samples used to calculate the end-member contributions and chemical budget are expressed in molar concentration (mmol/L).

(1) Rain inputs

Firstly, the contribution of the rain inputs end members to hydrochemistry is evaluated by chemical features of rain, andthe chemical composition data of rain is attached to Appendix C. The δ18O and δD for water is applied to determine concentration factor which is used to correct the influence of evaporation to hydrochemistry. This step is expressed by following equation:

Where are the major element concentrations which have been eliminated from the influence of rain inputs.are the major element concentrations, is the chemical concentrations of rain and is the concentration factor.

(2) Anthropogenic inputs

The are used here to give a further analysis of anthropogenic inputs. As mentioned in the manuscript, domestic sewage and mine drainage are considered as two major anthropogenic inputs in the study area. By comparing T08 and T19 in Zone 3, it isfound that Na+, Cl-, NO3- and SO42- have been affected significantly by anthropogenic inputs. So here a three end-members mixing model is applied to calculate the contribution of anthropogenic inputs to Na+, Cl-, NO3- and SO42-.

The three end-members model is expressed as follows:

For Na+

Where and is the molar ratio measured in the river (i=riv), or assumed for each end-member (i=DS, MDand natural). is the mixing proportions of the Na.

For Cl-

For SO42-

The mixing model is calculated by programming in MATLAB.

(3) Rock weathering

The major element concentrations with natural origins (eliminating both rain and anthropogenic inputs) are used to discriminating rock weathering input. It includes silicate, carbonate and evaporates weathering. A forward method is applied in this study to determine the contributions of carbonates, silicates and evaporates weathering to the major ions. The equations used are showed as follows:

[Ca]=[Casil]+[Cacar]+[Caeva]

[Mg]=[Mgsil]+[Mgcar]

[Na]=[Nasil]+[Naeva]

[K]=[Ksil]

where[Ca], [Mg], [Na] and [K] are their concentrations which have been corrected by eliminating the influence of rain and anthropogenic inputs. [Nasil]=[Na]-[Cl], [Naeva]=[Na]-[Nasil], [Casil]/[Nasil]=0.35, [Mgsil]/[Nasil]=0.24, [Caeva]=[SO4], [Cacar]=[Ca]-[Casil]-[Caeva], [Mgcar]=[Mg]-[Mgsil].

(4) Chemical budget

The chemical budget of rain,anthropogenic and rock weathering inputs to the TDS in the Taizi River are calculated based on the chemical balance method as below:

[Ca]=[Carain]+[Casil]+[Cacar]+[Caeva]

[Mg]=[Mgrain]+[Mgsil]+[Mgcar]

[Na]=[Narain]+[Nasil]+[Naeva]+[Naanth]

[K]=[Krain]+[Ksil]

[HCO3]=[HCO3car]+[HCO3sil]

[Cl]=[Clrain]+[Cleva]+[Clanth]

[SO4]=[SO4rain]+[SO4eva]+[SO4anth]

[NO3]=[NO3rain]+[NO3anth]

where [Xrain], [Xanth], [Xcar], [Xsil] and [Xeva] are the contribution of different end-members to element X and have been described in Section 4.3; [HCO3car] and [HCO3sil] is separated based on the ratio of ([Cacar]+[Mgcar])/([Casil]+[Mgsil]+[Nasil]+[Ksil]), [Cleva]=[Naeva].

The contributions of rain inputs, anthropogenic inputs and rock weathering (carbonate, silicate and evaporate weathering) are calculated as below:

Rain input=[Carain]+[Mgrain]+[Narain]+[Krain]+[Clrain]+[SO4rain]+[NO3rain]

Anthropogenic inputs=[Naanth]+[Clanth]+[SO4anth]+[NO3anth]

Carbonate weathering=[Cacar]+[Mgcar]+[HCO3car]

Silicate weathering=[Casil]+[Mgsil]+[Nasil]+[Ksil]+[HCO3sil]

Evaporate weathering=[Caeva]+[Naeva]+[Cleva]+[SO4eva]

The ratios are calculated as:

Ratio=