2018 | 71/3 | 173 – 184 | 6 Figs. | 2 Tabs. | 3 App. | www.geologia-croatica.hr Journal of the Croatian Geological Survey and the Croatian Geological Society 1. INTRODUCTION An important task in groundwater studies is the estimation of ground­water­mixing­ratios­and­identification­of­the­associated­ processes­in­order­to­effectively­protect­the­groundwater­from­the­ negative­impact­of­mixing­processes.­Furthermore,­there­is­an­ urgent­need­to­study­the­spatial­distribution­of­mixing­processes­ and­it­is­sensible­to­reveal­the­admixture­of­groundwater,­both­in­ terms­of­quantity­and­quality­of­these­resources.­These­processes­ can­include­groundwater­and­river­interaction­(BEYERLE­et­al.,­ 1999),­submarine­discharge­or­the­formation­of­brines­(BUR- NETT­et­al.,­2010),­geothermal­activity­(HAN­et­al.,­2010),­and­ interactions­between­aquifers­(RUEEDI­et­al.,­2005).­The­mixing­ ratio­from­different­groundwater­parameters­can­be­estimated­if­ the­mixed­waters­have­distinct­chemical­and/or­isotopic­compo- sition­signatures­and­also­using­hydrogeochemical­models­(mass­ balance­and­reaction-path­models).­ The­above­studies­of­mixing­ratios­were­calculated­mainly­ based­on­the­usefulness­of­only­one­or­two­parameters.­The­use­ of­only­a­couple­of­parameters­produces­reliable­results­which­ can­be­applied­when­the­a­priori­information­about­the­ground- water­system­is­readily­known.­Actually,­There­are­several­con- ditions­that­can­result­in­inaccurate­estimation­of­the­mixing­ratio­ i.e.,­sparse­information­about­the­groundwater­system,­a­hetero- geneous­database­of­chemical­and­isotopic­data­and­high­spatial­ Estimating Groundwater Mixing Ratios from Vertical Flux Processes due to Excessive Groundwater Pumping Using Hydrogeochemical Parameters and Nitrate Concentrations in the Bandung Basin, Indonesia Ahmad Taufiq1,2, Takahiro Hosono1,5, Irwan Iskandar3, Agus J. Effendi4 and Lambok M. Hutasoit2 1Kumamoto University, Graduate School of Science and Technology, Kumamoto, Japan; (correspondence author email address: ahmad.taufiq@pu.go.id) 2Faculty of Earth Science and Technology, Bandung Institute of Technology, Bandung, Indonesia 3Faculty of Mining and Petroleum Engineering, Bandung Institute of Technology, Bandung, Indonesia 4Faculty of Civil and Environmental Engineering, Bandung Institute of Technology, Bandung, Indonesia 5Priority Organization for Innovation and Excellence, Kumamoto University, Kumamoto, Japan doi: 10.4154/gc.2018.19 Abstract One crucial task in groundwater research and management is the estimation of groundwater mix- ing ratios. Here, estimations of mixing ratios are presented systematically and spatially for shal- low and deep groundwater in some areas of excessive groundwater pumping with different mag- nitudes of groundwater drawdown. The mixing ratios are estimated using two methods: (1) the total mixing ratio using all parameters, and (2) the mixing ratio using nitrate concentrations. The values for the total mixing ratio indicate that mixing between the shallow and the deep ground- water clearly occurs in all three depression areas, but with different ratios. The spatial distribution map of the total mixing ratio clearly shows that the largest mixing ratio occurs near the center of the cone of depression, and that the ratio decreases gradually away from the center of the de- pression area. There is a positive correlation among total mixing ratios, CFC-12 concentrations, and modeled vertical flux. Remarkably, the highest correlation is found between the correlation of the total mixing ratio and magnitude of vertical flux in the largest drawdown area. Meanwhile, comparison of the mixing ratio calculations by the different methods showed insignificant corre- lation which means nitrate is ineffective as the prevailing contaminant tracer for deep groundwa- ter in this basin. Overall, this study concludes that the method of total mixing ratio using all che- mical parameters is the most effective and consistent with previous methods. This study provides further proof that groundwater mixing between the shallow and deep groundwater systems has clearly occurred in the Bandung basin as an impact of excessive groundwater pumping. variations­of­the­end-members.­Under­these­conditions,­it­would­ be­worth­basing­the­calculation­of­total­mixing­ratios­on­all­the­ available­parameters­measured­because­the­uncertainty­of­esti- mation­can­be­reduced­(RUEEDI­et­al.,­2005).­­ Nowadays,­industrialization,­urbanization,­and­population­ growth­has­created­a­host­of­environmental­hazards,­reflected­in­ subsurface­environmental­problems­(FOSTER­&­CHILTON,­ 2003).­Moreover,­in­Asian­cities­as­very­rapidly­developing­areas,­ subsurface­environmental­problems­are­mostly­caused­by­exces- sive­groundwater­pumping,­groundwater­drawdown­and­ground- water­contamination­(TANIGUCHI­et­al.,­2008;­JAGO-ON­et­al.,­ 2009;­HOSONO­et­al.,­2011).­Specifically,­in­Indonesia,­a­signi- ficant­groundwater­drawdown­has­been­reported­throughout­big­ cities­such­as­Jakarta,­Bandung,­and­Semarang,­starting­from­in- creasing­of­water­demand­ leading­ to­ excessive­groundwater­ pumping­(WIRAKUSUMAH­&­DANARYANTO,­2004).­This­ excessive­groundwater­pumping­could­result­in­mixing­processes­ between­groundwaters­from­different­systems­or­aquifers.­ ­It­ might­cause­dilution­of­the­groundwater,­with­the­potential­to­ cause­the­degradation­of­groundwater­quality.­­ In­the­Bandung­basin,­human­and­industrial­activities­have­ influenced­the­groundwater­condition.­Since­the­early­1970s,­ many­textile­industrial­activities­have­taken­place­in­the­Bandung­ basin.­Industrialization,­along­with­urbanization­has­caused­a­ Article history: Manuscript received June 30, 2017 Revised manuscript accepted September 28, 2018 Available online October 24, 2018 Keywords: excessive pumping; groundwater mixing; mixing ratio; nitrate isotopes; Bandung Basin, Indonesia G eo lo gi a C ro at ic a Geologia Croatica 71/3174 significant­increase­in­water­demand­in­the­Bandung­Basin­with­ the­biggest­groundwater­consumer­being­the­textile­industries.­ Consequently,­there­are­three­large­groundwater­depression­areas­ within­these­industrial­and­urban­areas,­which­have­different­ magnitudes­of­groundwater­drawdown.­In­the­study­area,­exces- sive­groundwater­pumping­has­created­a­vertical­downward­flux­ from­the­shallow­to­deeper­aquifers,­which­has­caused­ground- water­mixing­in­those­areas.­Mixing­was­indicated­by­observed­ high­CFC-12­concentrations­in­deep­groundwater­and­the­vertical­ flux­was­confirmed­by­modeling­(TAUFIQ­et­al.,­2017).­ To­further­evaluate­mixing­in­the­groundwater,­it­is­neces- sary­to­calculate­mixing­ratios­that­can­be­achieved­using­hydro- geochemical­parameters.­Furthermore,­it­is­also­necessary­to­in- crease­our­understanding­of­the­mixing­process,­and­to­further­ prove­that­there­was­groundwater­mixing­due­to­excessive­pump- ing­in­the­Bandung­basin.­In­this­paper,­the­calculation­of­mixing­ ratios­between­shallow­and­deep­groundwater­will­be­presented­ systematically­and­spatially.­In­the­first­part­of­this­paper,­the­to- tal­mixing­ratio­will­be­determined­by­involving­all­measured­ parameters­to­eliminate­possible­observer­bias­and­reduce­esti- mation­uncertainty.­Meanwhile,­in­the­second­part,­the­mixing­ ratio­will­be­calculated­by­involving­only­one­parameter,­nitrate,­ as­a­contaminant­tracer.­For­further­evaluation­of­groundwater­ mixing,­the­estimated­mixing­ratios­will­be­compared­for­three­ depression­areas.­The­results­are­also­compared­with­results­from­ previous­investigations.­Finally,­the­two­methods­of­calculating­ mixing­ratios­will­be­evaluated­both­scientifically­and­practically.­ 2. STUDY AREA Bandung­Basin­is­located­in­the­centre­of­West­Java,­Indonesia­ and­is­one­of­the­most­developed­basins­in­Indonesia.­Bandung­ is­the­capital­of­West­Java­province,­the­most­densely­populated­ province­in­Indonesia,­and­the­centre­of­its­textile­industry.­The­ Bandung­Basin­has­an­area­of­about­2300­km2,­includes­five­ad- ministrative­regions,­and­currently­has­a­population­of­more­than­ 7­million­people.­The­basin­is­surrounded­by­mountains­up­to­ 2400­m­high,­consisting­of­late­Tertiary­and­Quaternary­volca- nic­deposits,­forming­an­intramontane­basin.­The­geology­of­this­ basin­is­classified­into­the­following­three­formations,­oldest­first­ (HUTASOIT,­2009):­Cikapundung­Formation,­Cibereum­For- mation­and­Kosambi­Formation­(Figure­1).­The­oldest­Cikapun- dung­Formation­is­composed­of­conglomerates,­and­compacted­ breccia,­tuff,­and­andesite­lava­and­forms­the­basement­of­the­ groundwater­basin.­The­overlying­Cibeureum­Formation­is­a­ fan-shaped­distribution­of­volcanic­deposit­of­Late­Pleistocene– Holocene­age.­The­youngest­Kosambi­formation­is­distributed­ in­the­centre­of­this­basin,­as­a­lake­deposit,­and­its­lithology­ consists­of­unconsolidated­claystone,­siltstone,­and­sandstone­of­ Holocene­age. Hydrogeologically,­the­Bandung­Basin­can­be­divided­into­ two­groundwater­systems:­a­shallow­one­and­a­deep­groundwater­ system.­The­shallow­groundwater­is­found­in­the­Kosambi­for- mation­or­the­unconfined­aquifer­with­a­local­flow­that­is­accessed­ from­dug­wells­with­depths­much­less­than­20­m.­Meanwhile,­the­ deep­groundwater­is­allied­with­the­Cibeureum­formation­as­a­ semiconfined­and­confined­aquifer­with­an­intermediate­and­re- gional­flow.­It­is­accessed­via­drilled­wells­mainly­in­­the­indus- trial­area­with­well­depths­exceeding­40­m.­To­calculate­mixing­ amounts,­it­is­assumed­that­there­is­a­mixture­of­water­from­the­ two­aquifer­systems:­shallow­and­deep­groundwaters­in­the­de- pression­areas­due­to­excessive­pumping­of­this­basin.­There­are­ three­large­groundwater­depression­areas­in­the­industrial­­complex:­ Cimahi­area­(CMHI),­Rancaekek­area­(RCK),­and­Dayeuhkolot­ area­(DHYK)­(Figure­1b),­that­are­well-known­by­their­codes­as­ the­investigation­areas.­Monitoring­of­the­deep­groundwater­levels­ was­accomplished­by­the­basin­authority:­the­Office­of­Energy­ and­Mineral­Resources,­West­Java­Province.­The­results­show­ that­for­the­deep­groundwater­potential­over­the­past­twenty­years­ the­CMHI­area­has­the­largest­rate­of­groundwater­drawdown­de- cline:­1–2­m/year,­the­RCK­area­is­declining­at­a­rate­of­0–1­m/ year,­and­the­DHYK­area­is­declining­at­a­slightly­lower­rate­stil.­ According­ to­TAUFIQ­et­al.­ (2017),­ the­groundwaters­ in­ the­ Bandung­Basin­could­be­determined­based­on­their­hydrogeo- chemical­types,­which­are:­a­Ca-HCO3­type­for­the­shallow­aquifer­ and­a­Na-HCO3­type­for­the­deep­groundwater.­But­there­were­ some­seemingly­random­occurrences­of­the­Ca-HCO3­type­in­the­ deep­groundwater­at­three­depression­areas­that­were­identified­ as­the­result­of­groundwater­mixing.­ Figure 1. Location map of the sampling points plotted on a geological map (HUTASOIT, 2009): a) for shallow groundwater, b) for deep groundwater. The points with potential contours (TAUFIQ et al., 2017) and the locations of their end-members. The shallow groundwater flows from the periphery to the centre of the basin meanwhile, the deep groundwater was identified where there were three depression areas: CMHI area, RCK area and DHYK area. G eologia C roatica Taufiq et al.: Estimating Groundwater Mixing Ratios from Vertical Flux Processes due to Excessive Groundwater Pumping ... 175 3. METHODOLOGY 3.1. Sampling and methods In­this­study,­all­the­hydrogeochemical­data­were­used­for­the­ shallow­and­deep­groundwater­that­have­been­obtained­for­deter- mining­water­composition­in­the­Bandung­Basin­(TAUFIQ­et­al.,­ 2017)­(Appendix­1).­A­total­of­40­shallow­and­65­deep­ground- water­samples­were­collected­between­May­to­July­2015.­­Some­ in-situ­tests,­such­as­temperature,­pH,­dissolved­oxygen­(DO),­ electrical­conductivity­(EC),­and­oxidation–reduction­potential­ (ORP)­of­the­water­samples­were­measured­in­the­field­with­d­ quality­minimal­atmospheric­contact,­using­a­portable­meter­of­ WM-32EP­(TOA-DKK­Co,­Tokyo­Japan).­Water­samples­were­ collected­separately­for­each­analytical­procedure­(methods­de- tailed­in­TAUFIQ­et­al.,­2017):­major­ions­(Na+,­K+,­Ca2+,­Mg2+,­ Cl-,­SO4 2-­and­HCO3 -)­and­stable­isotopes­(δ18O­and­δ2H).­For­ some­trace­element­concentrations,­Fe2+­and­Mn2+­concentrations­ were­analyzed­using­an­inductively­coupled­plasma­mass­spec- trometer­(ICP-MS)­(NexION300D,­PerkinElmer,­USA)­and­using­ standard­mode­and­kinetic­energy­discrimination­(KED)­mode.­ Replicate­analyses­were­carried­out­to­check­the­precision­and­ accuracy­of­the­results.­Precision­was­better­than­±10­%,­evalu- ated­from­the­repeated­measurement­of­standard­reference­solu- tions­with­certified­concentrations. For­analysis­of­nitrate­concentrations­and­nitrate­isotope­ra- tios,­water­samples­were­also­collected­separately­(methods­de- tailed­in­HOSONO­et­al.,­2013;­2014):­Nitrate­concentration­was­ measured­by­ion­chromatography­(DIONEX­ICS­1600,­Thermo­ Fisher­Scientific­Inc.,­USA);­and­the­nitrate­isotope­compositions­ were­determined­following­the­denitrifier­method­of­SIGMAN­et­ al.­(2001)­and­CASCIOTTI­et­al.­(2002).­Using­this­method,­a­ sample­containing­nitrate­was­converted­to­nitrous­oxide­(N2O)­ by­denitrifying­bacteria­that­lack­N2O-reductase­activity.­This­ was­then­stripped­from­the­sample­vial­using­helium­carrier­gas,­ purified­using­cryogenic­trapping­(Thermo­Fisher­Precon­Sys- tem),­chromatographically­separated­(Thermo­Fisher­Gas­Bench),­ and­analyzed­using­mass­spectrometry­(Thermo­Fisher­Delta­V­ Advantage).­ Isotope­values­were­calibrated­using­ the­United­ States­Geological­Society­(USGS)­and­International­Atomic­En- ergy­Agency­(IAEA)­nitrate­standards:­USGS-34,­USGS-35,­and­ IAEA-N3.­Based­on­replicate­measurements­of­standards­and­ samples­(n­¼­288),­the­analytical­precisions­for­δ15N-NO3 - and δ18O-NO3 -­were­better­than­±0.2­0/00­and­±0.3­0/00,­respectively.­ The­nitrogen­isotope­ratio­for­powdered­samples­was­determined­ by­mass­spectrometry­interfaced­with­a­CNS­elemental­analyzer­ (Thermo­Fisher­Flash­2000).­The­analytical­precision­of­the­ana- lysis­was­better­than­±­0.15­0/00. 3.2. Calculation method of the mixing ratio Nomenclature C­­concentration­­ m­­mixing­ratio­of­a­parameter­i P­­groundwater­parameter­­ n­­ total­number­of­parameters­ S­­sample­ w­­weight­of­parameter­ σ­ standard­deviation­ The­calculation­of­mixing­ratios­in­this­study­was­applied­using­ some­equations­from­the­following­procedures­(RUEEDI­et­al.,­ 2005;­HAN­et­al.,­2010).­Firstly,­the­calculation­used­all­the­pa- rameters­(S)­for­two­end-members:­end-member­1­for­shallow­ groundwater­(C1)­and­end-member­2­for­deep­groundwater­(C2).­ The­end­members­were­the­most­representative­samples­which­ had­natural­groundwater­quality.­­The­two­previous­studies­were­ considered­that­had­characterized­natural­groundwater­in­the­ Bandung­basin.­As­mentioned­by­WAGNER­&­SUKRISNO­ (1998)­and­TAUFIQ­et­al.­(2017),the­shallow­groundwater­was­ characterized­generally­as­an­Ca-HCO3-type,­generally­low­oxy- gen­levels,­elevated­Fe2+­concentration,­elevated­Mn2+­concentra- tions,­ ­ and­high­CFC-12­concentration,­meanwhile­ the­deep­ groundwater­was­characterized­generally­by­the­Na-HCO3-type,­ with­elevated­Cl–­concentrations­and­no­CFC-12­concentration. The­estimation­began­by­calculating­the­mixing­ratio­(mp) for­every­concentration­(C)­of­each­parameter­(p)­using­an­equa- tion­ (1).­ The­ equations­ (1)­ –­ (4)­were­ applied­ by­ following­ RUEEDI­et­al.­(2005); m C C C C P S P P P P = - - , , , , 2 1 2 (1)­ At­every­parameter,­its­standard­deviation­(σp) was estimated using­equation­(2); s s s sP P P S P P P P S P P P C C C C C C C= -( ) -( ) + -( ) +1 1 2 2 2 1 2 2 1 2 2 2 2 2 , , , , , , , , , SS P PC, , -( )1 2 ­(2) The­total­mixing­ratio­(m m w w P n P P P n P = = = å å 1 1 )­was­calculated­by­averaging­the­ ratios­of­all­parameters­(n)­using­equation­(3),­and­the­usefulness­ of­each­parameter­or­the­weight­(wp)­using­equation­(4); m m w w P n P P P n P = = = å å 1 1 (3) w P P = 1 2s (4) Next,­the­mixing­ratio­was­estimated­using­only­one­para- meter­and­only­using­equation­(1).­The­parameter­was­nitrate­con- centration,­selected­considering­its­nitrate­isotopes,­the­stable­ isotope­ratios­of­nitrogen­and­oxygen.­It­was­selected­because­the­ nitrate­concentration­is­an­ongoing­contaminant­in­this­basin.­ Moreover,­since­the­1970s,­nitrate­isotopes­are­a­powerful­tracer­ for­revealing­concealed­contaminant­sources­(i.e.­KREITLER,­ 1979;­KAPLAN­&­MAGARITZ,­1986;­HOSONO­et­al.,­2013).­­ The­possible­source­of­Nitrate­could­be­identified­from­groups­of­ isotope­composition­ranges,­using­the­approach­of­KENDALL,­ (1998)­and­SINGLETON­et­al.­(2007):­Group­A­(the­nitrification­ of­NH4 +­in­fertilizer;­−8­to­+5­‰,­−5­to­+15­‰,­for­δ15N-NO3 - and δ18O-NO3 -,­respectively);­Group­B­(soil­nitrogen;­+3­to­+8­‰,­−5­ to­+15­‰);­Group­C­(manure­and­sewage-derived­NO3 -:­0­to­+25­ ‰,­−5­to­+15­‰);­Group­D­(fertilizer­;­−5­to­+8­‰,­+15­to­+25­ ‰),­Group­E­(precipitation­;­−5­to­+10­‰­and­+18­to­+70­‰),­re- spectively­(Figure­5a). RESULTS 4.1. Selection of end members Firstly,­two­end-members­were­selected,­one­for­shallow­ground- water­and­one­for­deep­groundwater,­based­on­assumptions­of­ their­major­differences­in­terms­of­hydrogeochemical­signatures­ and­based­on­the­groundwater­system­of­the­study­area.­The­two­ end-members­for­the­dual­groundwater­system­in­the­Bandung­ basin­were:­ End-member­1­–­shallow­groundwater.­This­groundwater­ was­characterized­by­elevated­Ca2+­concentrations­of­approxi- mately­50­mg/l,­elevated­HCO3 –­concentrations­of­approximately­ 200­mg/l,­low­Na+ concentrations­around­35­mg/l,­K+­concentra- tions­around­10­mg/l,­Mg2+­concentrations­round­15­mg/l,­low­ Cl–­and­ low­concentrations­of­around­40­mg/l­ (WAGNER­&­ SUKRISNO,­1998).­The­Ca2+­concentration­and­CFC-12­concen- G eo lo gi a C ro at ic a Geologia Croatica 71/3176 trations­in­shallow­groundwater­were­higher­than­in­the­deep­ groundwater­(TAUFIQ­et­al.,­2017).­ End-member­2­–­deep­groundwater.­This­groundwater­was­ characterized­by­elevated­Na+ concentrations­of­approximately­ 50­mg/l,­elevated­Mg2+­concentrations­around­20­mg/l,­elevated­ Cl–­concentrations­of­around­45­mg/l,­and­HCO3 –­concentrations­ of­about­250­mg/l,­low­Ca2+­concentrations­around­40­mg/l,­low­ K+­concentrations­around­10­mg/l­(WAGNER­&­SUKRISNO,­ 1998).­Low­or­negative­values­for­ORP­(Oxidation-Reduction­ ­Potential)­and­no­CFC-12­concentrations­(TAUFIQ­et­al.,­2017)­ mean­that­this­groundwater­is­characterized­by­either­reducing­ conditions­of­the­confined­aquifer­or­that­the­water­is­old­and­un- contaminated.­ Notably,­persistent­contaminants­or­‘unnatural’­substances­ that­affect­the­major­chemistry­or­isotopic­groundwater­signature­ were­excluded­from­the­definition­of­the­natural­parameters.­Ac- cording­to­WAGNER­&­SUKRISNO­(1998):­the­shallow­ground- water­had­elevated­Fe2+concentration­if­it’s­values­exceed­1­mg/l­ (defined­as­elevated­substance­1)­and­Mn2+­concentration­if­it’s­ values­exceed­0.5­mg/l­(defined­as­elevated­substance­2).­Mean- while,­according­to­TAUFIQ­et­al.­(2017):­the­shallow­ground- water­had­elevated­levels­of­CFC-12­concentration­if­this­exceeds­ >576­pptv­(defined­as­elevated­substance­3)­and­for­ the­deep­ groundwater,­it­had­elevated­substances­if­CFC-12­concentrations­ were­observed,­as­a­young­(modern)­tracer.­In­addition,­nitrate­ concentration­was­also­identified­as­elevated­substance­4.­Since­ there­was­a­study­about­its­natural­background­values,­the­cut-off­ level­of­3­mg/l­was­chosen­based­on­the­observations­in­the­Band- ung­Basin­(TAUFIQ­et­al.,­2018). The­selection­of­end­members­was­undertaken­by­taking­ samples­that­had­no­unnatural­substances­and­were­located­at­the­ furthest­point­possible­from­a­potential­contaminant­source­for­ every­depression­areas.­­The­shallow­groundwater­sample­was­ the­closest­location­to­the­recharge­area­or­the­periphery­of­this­ basin­and­the­deep­groundwater­was­the­furthest­location­from­ the­depression­area­or­industrial­area.­­A­sample­number­S7­was­ chosen­as­end-member­1­(from­4­samples)­because­its­location­ was­the­closest­to­the­northern­area;­and­D46­for­end-member­2­ Figure 2. The spatial distribution map of the total mixing ratios for all samples of deep groundwater in the depression areas: CMHI area (a), RCK area (b), and DHYK area (c). The points with potential contours from observation wells (TAUFIQ et al., 2017). G eologia C roatica Taufiq et al.: Estimating Groundwater Mixing Ratios from Vertical Flux Processes due to Excessive Groundwater Pumping ... 177 (from­15­samples)­because­it­was­located­furthest­away­from­the­ depression­area.­Selection­of­end­members­in­the­CMHI­area­is­ presented­in­Table­1,­and­plotted­in­Figure­1.­Using­the­same­ap- proach­for­the­RCK­and­DHYK­areas,­S12­and­S11­were­selected­ as­end-members­of­the­shallow­and­groundwater­samples­respec- tively;­and­D27­and­D30a­as­end­members­of­deep­groundwater­ samples.­The­selection­of­ the­end­members­for­ the­RCK­and­ DHYK­area­is­presented­in­Appendix­1.­ 4.2. Calculation of the total mixing ratio To­calculate­the­total­mixing­ratio,­all­the­above­equations­were­ applied.­The­calculation­was­ideal­for­estimating­the­total­mixing­ ratio­because­it­used­all­the­important­parameters,­7­major­ions,­ and­2­stable­isotopes.­The­calculated­total­mixing­ratios­vary­ from­0.01­to­0.69.­These­results­indicate­that­there­was­mixing­in­ deep­groundwater­due­to­a­recharging­vertical­flux­from­the­shal- lower­to­the­deeper­waters.­In­the­CMHI­area,­the­mean­of­the­ total­mixing­ratio­was­0.43­which­is­larger­than­the­other­areas.­ The­results­are­presented­in­Appendix­2,­plotted­in­Figure­3a­and­ summarized­in­Table­2. The­spatial­distribution­pattern­of­mixing­ratios­shows­a­clear­ relationship­to­the­contour­pattern­of­the­depression­areas­(as­pre- sented­in­Figure­2).­The­spatial­distribution­map­of­the­total­mix- ing­ratio­in­the­CMHI­area­clearly­shows­that­a­larger­mixing­ra- tio­was­found­close­to­the­center­of­the­depression­cone,­and­the­ mixing­ratio­gradually­decreases­towards­the­edges­of­the­cone.­ This­pattern­was­also­observed­in­the­RCK­and­DHYK­areas,­but­ is­less­pronounced.­­It­is­due­to­the­biggest­vertical­flux­of­water­ occurring­at­the­centre­of­the­cone,­meaning­that­the­deepest­­ drawdown­causes­subsequent­groundwater­mixing­between­shal- low­and­deep­aquifers.­Thus,­the­gradual­decrease­to­the­edge­of­ the­depression­zone­is­also­spatially­controlled­by­the­depth­of­ drawdown.­The­mixing­pattern­ in­ the­CMHI­area­where­ the­ greatest­drawdown­occurred­is­more­spatially­related­to­the­cone­ of­depression­than­for­the­other­areas. 4.3. Calculation of the nitrate mixing ratio The­range­of­nitrate­concentrations­is­between­0.20­and­20.69­ mg/l;­none­of­the­analyzed­samples­(n­=­93)­exceeded­the­World­ Health­Organization­limit­of­50­mg/l­for­both­the­shallow­and­ deep­groundwaters­in­this­basin,­but­some­of­the­shallow­ground- waters­exceeded­Indonesia’s­standard­of­10­mg/l.­Notably,­in­the­ Bandung­Basin,­the­shallow­groundwater­tended­to­be­more­ni- trate­enriched­than­the­deep­one,­as­depicted­in­Figure­4.­This­ enriched­trend­of­both­groundwaters­will­be­compared­in­detail­ in­a­future­paper­(TAUFIQ­et­al.,­2018­in­press).­ Figure 3. Correlation between (a) magnitude of CFC-12 concentrations and the total mixing ratio, (b) magnitude of the vertical flux and the total mixing ratio. The variously colored dashed lines indicate the regression line of each correlation for each area. Figure 4. Distribution maps of nitrate concentrations for (a) shallow groundwater and (b) deep groundwater plotted on a land use map (BAKORSORTANAL, 2009). G eo lo gi a C ro at ic a Geologia Croatica 71/3178 Ta bl e 1. H yd ro ge oc he m ic al d at a in cl ud in g th ei r e nd m em be rs (C M H I a re a) . a) S ha llo w g ro un dw at er                                 Sa m pl in g N o (S x) 7 M aj or io ns 2 St ab le is ot op es In sit u te st N itr at e iso to pe s Id en tifi ed c on ta m in an ts N ot e Ca 2+ M g2 + N a+ K+ H CO 3- Cl - SO 4- δ1 8O δ2 H D O O RP δ1 8O - N O 3- δ1 5N - N O 3- (1 ) F e (2 ) M n (3 ) CF C- 12 (4 ) N O 3- m g/ l m g/ l m g/ l m g/ l m g/ l m g/ l m g/ l (0 /0 0) (0 /0 0)   m V (0 /0 0) (0 /0 0) pp b pp b pp tv m g/ l 7 75 .5 0 9. 10 16 .7 0 8. 15 27 6. 67 5. 80 90 .1 5 -5 .2 6 -4 3. 97 4. 28 85 .0 0 5. 7 10 .2 0. 99 0. 19 50 2 3. 99 en d m em be r 1 1 38 .2 2 11 .0 5 42 .2 6 10 .6 3 27 7. 38 20 .2 4 9. 00 -5 .1 6 -4 2. 97 4. 86 90 .0 0 2. 0 21 .6 7. 29 0. 23 24 9 5. 04   2 38 .1 0 11 .0 0 42 .4 4 10 .6 7 27 8. 66 20 .4 4 8. 70 -5 .1 6 -4 2. 97 3. 73 90 .0 0 9. 7 22 .8 10 .8 5 17 .4 9 43 7 5. 04   3 38 .8 9 12 .2 4 46 .7 8 6. 54 22 7. 16 13 .4 9 41 .7 7 -5 .3 1 -4 3. 51 4. 11 95 .7 5 -1 2. 2 15 .8 6. 92 11 .4 0 23 0 12 .0 9 co nt am in at ed (4 ) 31 55 .1 1 15 .4 5 28 .2 2 11 .6 6 17 6. 23 77 .4 5 10 3. 60 -5 .4 6 -4 4. 89 5. 66 10 0. 00 19 .9 14 .3 1. 41 0. 37 16 4 4. 00   9 51 .1 3 18 .0 9 23 .8 7 9. 44 12 1. 08 44 .0 8 87 .2 1 -6 .9 1 -4 2. 83 5. 01 84 .0 0 -1 .5 9. 6 2. 30 0. 59 76 8 10 .4 3 co nt am in at ed (3 .4 ) 28 42 .0 0 16 .7 3 60 .2 1 9. 87 17 6. 23 47 .2 2 1. 39 -4 .2 0 -3 8. 43 1. 92 26 .4 0 3. 4 9. 0           4 51 .0 0 18 .1 2 23 .9 8 9. 50 12 1. 1 44 .3 5 87 .2 0 -6 .9 1 -4 2. 83 5. 77 19 1. 00 -1 .5 9. 6 2. 62 19 .3 2 76 9 2. 28 co nt am in at ed (3 .4 ) 5 65 .1 0 25 .4 5 27 .5 3 11 .4 5 17 6. 35 77 .5 7 10 4. 71 -5 .4 0 -3 5. 00 6. 67 10 2. 00 2. 4 11 .0 1. 43 0. 33 57 9 9. 97 co nt am in at ed (3 ) 27 61 .1 0 25 .4 5 37 .4 4 11 .4 0 17 6. 33 77 .1 2 10 4. 23 -5 .4 0 -3 5. 00 4. 72 20 7. 00 1. 3 7. 1 0. 97 3. 91 59 5 3. 95 co nt am in at ed (3 ) 13 56 .6 0 18 .5 4 76 .0 8 34 .4 3 37 1. 45 91 .0 6 32 .5 1 -5 .3 5 -4 5. 00 2. 08 11 6. 00 3. 1 9. 3 2. 54 6. 48 40 4. 78   b) D ee p gr ou nd w at er                                 Sa m pl in g N o (D x) 7 M aj or io ns 2 St ab le is ot op es In sit u te st N itr at e iso to pe s Id en tifi ed c on ta m in an ts N ot e Ca 2+ M g2 + N a+ K+ H CO 3- Cl - SO 4- δ1 8O δ2 H D O O RP δ1 8O - N O 3- δ1 5N - N O 3- (1 ) F e (2 ) M n (3 ) CF C- 12 (4 ) N O 3- m g/ l m g/ l m g/ l m g/ l m g/ l m g/ l m g/ l (0 /0 0) (0 /0 0)   m V (0 /0 0) (0 /0 0) pp b pp b pp tv m g/ l 10 60 .2 23 .2 33 .5 8. 7 28 0. 9 21 .2 13 .8 -6 .2 -4 6. 8 4. 1 79 .0 20 .7 16 .5 na na 40 5. 2 1. 3   1 23 .8 10 .7 16 .9 7. 8 18 4. 7 4. 0 8. 6 -5 .5 -4 4. 2 3. 8 92 .0 38 .0 28 .7 na na 0. 0 1. 6   9 59 .9 22 .9 32 .6 7. 5 27 5. 2 20 .8 12 .7 -5 .4 -3 8. 3 2. 1 51 .2 20 .7 16 .5 na na 0. 0 1. 4   2 28 .0 13 .0 24 .0 9. 3 21 9. 2 9. 8 14 .5 -6 .2 -4 6. 6 5. 2 25 .5     na na 32 1. 6 1. 1 co nt am in at ed (3 ) 5a 28 .8 12 .8 23 .8 9. 3 21 7. 4 8. 8 14 .5 -6 .2 -4 5. 6 2. 5 48 .1 15 .6 18 .4 na na 0. 0 3. 0 co nt am in at ed (4 ) 3 27 .9 13 .9 23 .9 9. 2 21 7. 9 9. 8 15 .2 -5 .6 -4 4. 8 2. 1 66 .9     na na 12 9. 5 1. 1 co nt am in at ed (3 ) 5 68 .1 26 .7 86 .3 14 .9 29 5. 7 10 4. 6 54 .0 -5 .9 -4 5. 5 4. 3 39 .3 15 .4 18 .0 na na 31 4. 7 1. 9 co nt am in at ed (3 ) 8 59 .9 23 .1 32 .5 7. 4 27 9. 5 20 .9 13 .4 -5 .5 -4 4. 2 2. 1 96 .0 38 .0 28 .7 na na 0. 0 4. 0 co nt am in at ed (4 ) 6c 43 .9 18 .9 30 .9 9. 9 28 8. 4 21 .7 21 .9 -5 .7 -4 4. 7 2. 3 75 .7     na na 18 6. 3 1. 2 co nt am in at ed (3 ) 6 57 .0 24 .1 63 .1 11 .5 20 6. 7 45 .2 25 .2 -4 .7 -3 9. 9 2. 1 -1 0. 8 13 .6 19 .8 na na 29 2. 7 3. 2 co nt am in at ed (1 , 4 ) 4 29 .0 13 .2 24 .9 9. 5 21 9. 4 10 .0 15 .5 -6 .1 -4 6. 5 3. 4 31 .2 21 .2 16 .5 na na 24 3. 0 1. 1 co nt am in at ed (3 ) 4a 55 .8 23 .8 62 .5 10 .9 20 5. 4 44 .2 24 .1 -6 .1 -4 6. 5 3. 0 -6 8. 5 21 .4 16 .1 na na 0. 0 1. 1   6b 45 .2 19 .3 32 .6 10 .5 29 0. 5 21 .9 22 .4 -5 .6 -4 4. 6 5. 8 61 .3     na na 11 7. 9 1. 2 co nt am in at ed (3 ) 6a 44 .9 19 .2 31 .9 10 .2 28 9. 8 20 .7 21 .9 -5 .6 -4 4. 6 1. 9 71 .9     na na 80 .0 0. 2 co nt am in at ed (3 ) G eologia C roatica Taufiq et al.: Estimating Groundwater Mixing Ratios from Vertical Flux Processes due to Excessive Groundwater Pumping ... 179 7c 45 .2 18 .8 32 .6 10 .5 29 0. 5 21 .9 22 .4 -6 .1 -4 6. 3 2. 7 17 .0 -4 .8 -2 .7 na na 16 9. 2 5. 3 co nt am in at ed (3 , 4 ) 7 60 .8 21 .0 73 .6 11 .2 38 6. 9 31 .8 98 .1 -5 .9 -4 0. 7 3. 0 -6 0. 4 20 .0 13 .0 na na 14 3. 1 4. 1 co nt am in at ed (3 , 4 ) 7b 60 .1 24 .0 33 .7 9. 9 28 5. 8 21 .9 13 .8 -6 .0 -4 0. 8 2. 7 14 .0 11 .9 16 .5 na na 12 6. 6 3. 6 co nt am in at ed (3 , 4 ) 7a 60 .6 20 .8 72 .9 11 .1 38 5. 1 30 .4 97 .9 -5 .9 -4 0. 8 6. 3 -4 4. 1 20 .7 18 .0 na na 86 .7 3. 6 co nt am in at ed (3 , 4 ) 47 25 .1 11 .1 31 .6 8. 9 25 3. 5 4. 0 4. 0 -6 .5 -4 5. 5 2. 8 12 4. 6 6. 6 8. 9 na na 23 .2 0. 4 co nt am in at ed (3 ) 46 24 .8 11 .1 31 .2 8. 9 25 0. 8 3. 9 5. 9 -6 .0 -4 5. 5 3. 2 11 0. 0 20 .1 12 .6 na na 0. 0 0. 3 en d m em be r 2 45 60 .8 13 .0 73 .7 10 .9 38 8. 5 32 .0 90 .8 -6 .2 -4 5. 6 2. 8 -3 0. 3 21 .2 19 .1 na na 0. 0 1. 7   12 37 .9 19 .7 22 .0 10 .5 30 5. 2 7. 8 9. 1 -6 .0 -4 6. 7 3. 1 38 .7 8. 9 18 .0 na na   2. 8   12 d 39 .0 18 .7 23 .1 11 .8 28 0. 7 8. 6 9. 3 -4 .6 -3 8. 3 2. 0 -3 2. 0     na na 0. 0 3. 0 co nt am in at ed (4 ) 12 f 38 .9 19 .9 22 .9 12 .0 29 9. 9 8. 1 9. 2 -5 .4 -4 2. 5 2. 3 -6 0. 4 33 .7 38 .3 na na 0. 0 3. 0 co nt am in at ed (4 ) 1 37 .2 15 .7 25 .0 8. 9 26 7. 8 2. 0 4. 6 -5 .4 -4 2. 5 4. 3 64 .4     na na 0. 0 3. 0 co nt am in at ed (4 ) 15 79 .3 34 .6 18 8. 3 18 .6 58 3. 3 14 1. 3 1. 6 -5 .5 -4 4. 9 3. 5 -1 4. 0 -1 .5 6. 0 na na 25 5. 3 0. 2 co nt am in at ed (3 ) 15 a 23 .8 8. 9 78 .7 9. 1 30 2. 8 43 .8 2. 7 -6 .8 -4 4. 0 2. 4 31 .2     na na 11 6. 6 2. 6 co nt am in at ed (3 ) 34 23 .3 8. 6 75 .5 9. 1 30 0. 7 42 .6 2. 6 -6 .0 -4 2. 6 2. 3 -6 0. 4 18 .9 12 .4 na na 0. 0 0. 4   39 b 24 .2 9. 6 78 .5 8. 8 30 2. 7 43 .4 2. 5 -6 .5 -4 2. 2 3. 2 50 .6 8. 5 25 .8 na na 0. 0 2. 5   So ur ce d at a: M aj or io ns , s ta bl e iso to pe s i ns itu te st (T AU FI Q e t a l., 20 18 a) ; F e2 +, M n2 + an d N itr at e iso to pe s ( th is st ud y)               Table 2. Summary of the statistical analysis from the calculated mixing ratios. a) CMHI area         Descriptive statistic CFC-12 concentration*) Vertical flux*) Total mixing ratio Nitrate mixing ratio Mean 188.24 169,544 0.43 0.29 Standard Error 26.48 20,299 0.05 0.10 Median 156.17 178,186 0.49 0.26 Standard Deviation 105.91 81,195 0.19 0.26 Range 382.04 296,752 0.68 0.78 Minimum 23.20 4,008 0.01 0.00 Maximum 405.24 300,760 0.69 0.78 n 16 16 16 7 b) RCK area         Mean 114.80 201,819 0.15 0.29 Standard Error 25.72 41,518 0.03 0.11 Median 100.34 235,762 0.12 0.13 Standard Deviation 92.72 155,347 0.10 0.30 Range 290.34 464,918 0.27 0.77 Minimum 11.72 11,262 0.00 0.02 Maximum 302.06 476,180 0.27 0.79 n 13 15 15 7 c) DHYK area         Mean 211.29 161,058 0.12 0.29 Standard Error 41.63 91,076 0.04 0.12 Median 247.21 29,543 0.04 0.19 Standard Deviation 117.74 340,774 0.16 0.29 Range 346.06 1,303,381 0.46 0.70 Minimum 17.73 101 0.00 0.00 Maximum 363.78 1,303,482 0.46 0.70 n 8 14 14 6 *) Data from TAUFIQ et al. (2017) The­nitrogen­isotope­ratios­of­the­possible­source­materials­ revealed­unique­signatures­with­some­compositional­variations.­ The­δ15NNO3­of­groundwater­samples­ranged­from­−1.2­‰­to­ 47‰,­and­δ18ONO3­ranged­from­−12.2­‰­to­33.7­‰.­Differences­ in­isotopic­composition­between­the­shallow­and­deep­ground- water­were­not­discovered,­possibly­due­to­the­most­likely­and­ predominant­source­of­nitrate­contamination­in­the­investigated­ areas­being­septic­waste­leakage­(Group­C)­from­the­urban­area.­ For­the­purpose­of­this­research­to­investigate­groundwater­ mixing­in­the­study­areas,­only­nitrate­concentrations­in­the­three­ cone-of-depression­areas­were­focused­on.­Notably,­only­deep­ groundwater­containing­CFC-12­concentrations­were­selected­ which­implies­either­that­it­was­recharged­from­shallow­(younger)­ groundwater­(TAUFIQ­et­al.,­2017)­or­that­the­nitrate­was­also­ possibly­recharged­from­the­shallow­groundwater.­According­to­ KENDALL­(1998)­and­SINGLETON­et­al.­(2007)­the­nitrate­in­ these­areas­can­be­identified­from­the­following­potential­source­ groups:­A­(3­samples),­B­(13­samples),­C­(34­samples),­and­D­(5­ samples),­presented­in­Appendix­3­and­Figure­5.­In­addition,­deep­ groundwater­samples­with­low­DO­values­(<­2­mg/l)­were­omit- ted­because­of­the­significant­denitrification­that­preferentially­ occurs­(BÖHLKE­et­al.,­2002).­The­deep­groundwater­samples­ in­the­depression­cone­areas­appeared­to­have­been­recharged­ from­shallow­groundwater­that­contained­septic­tank­waste­and/ or­manure­waste­(Group­C,­as­mentioned­in­Section­3.2),­so­only­ these­samples­in­Group­C­were­used­to­determine­the­nitrate­mix- ing­ratios.­ G eo lo gi a C ro at ic a Geologia Croatica 71/3180 The­nitrate­mixing­ratios­were­calculated­using­only­equa- tion­(1)­with­the­same­end-members­as­the­total­mixing­ratio­cal- culation­(Section­4.2).­The­calculated­nitrate­mixing­ratios­were­ between­0.01­and­0.78.­The­calculated­mixing­ratios­for­nitrate­ indicate­ that­ the­mixing­ between­ the­ shallow­ and­ the­ deep­ groundwater­clearly­occurs­in­all­three­depression­areas,­but­with­ different­ratios.­Both­the­differences­in­nitrate­mixing­ratios­and­ total­mixing­ratios­reflect­the­variation­in­magnitude­of­the­flux­ from­shallower­to­deeper­groundwaters­and­are­controlled­by­the­ degree­of­drawdown­from­pumping.­The­results­are­presented­in­ Appendix­3.,­plotted­in­Figure­3b.­and­summarized­in­Table­2. 5. DISCUSSION For­further­evaluation­of­groundwater­mixing­between­the­shal- low­and­deep­groundwaters­caused­by­excessive­pumping,­the­ calculated­total­mixing­ratios­were­compared­with­other­earlier­ results­of­TAUFIQ­et­al.­(2018a).­The­first­discussion­involves­the­ relationship­between­the­total­mixing­ratio­with­2­previous­me- thods:­between­the­magnitude­of­CFC-12­concentrations,­when­ it­is­used­as­a­hydrogeochemical­tracer­and­the­magnitude­of­ver- tical­flux­as­determined­by­modeling­(Table­2;­TAUFIQ­et­al.,­ 2017).­The­last­discussion­involves­a­comparison­of­calculation­ of­mixing­ratios­using­all­the­parameters­against­using­only­one­ parameter. The­total­mixing­ratios­had­a­positive­significant­correlation­ (p­<­0.05,­N­=­14)­with­the­magnitude­of­vertical­flux­(Figure­3a)­ as­determined­by­modeling­in­all­of­the­three­depression­areas,­ but­there­was­a­lower­positive­significant­correlation­with­the­ magnitude­of­CFC-12­concentrations­(p­>­0.05,­N­=­14)­(Figure­ 3b).­They­had­different­coefficients­of­correlation­for­each­depres- sion­area.­Remarkably,­the­highest­significant­correlation­was­ found­between­the­correlation­of­the­total­mixing­ratio­and­mag- nitude­of­vertical­flux­in­the­CMHI­area­(r­=­0.81,­p­<­0.01,­N­=­16).­ The­CMHI­area,­with­the­largest­groundwater­drawdown,­had­ the­highest­mean­total­mixing­ratio,­CFC-12­concentrations­and­ vertical­flux.­The­other­two­areas­followed­a­similar­pattern­but­ with­a­lower­mean­value.­This­indicates­that­the­method­of­the­ total­mixing­ratio­is­as­effective­as­the­two­other­methods,­the­ hydrogeochemical­tracer­and­the­modeling,­in­revealing­ground- water­mixing.­ The­two­methods­of­calculating­mixing­ratio­were­compared­ to­show­the­relationship­between­using­all­parameters­with­using­ only­one­selected­parameter.­The­comparison­of­calculating­mix- ing­ratio­by­using­all­parameters­and­by­using­only­nitrate­(Figure­ 6)­shows­a­positive­correlation­(p­>­0.05,­N­=­6).­The­CMHI­area­ had­the­largest­total­mixing­ratio­and­also­the­largest­nitrate­ mixing­ratio­with­the­highest­coefficient­of­correlation­(r­=­0.36,­ Figure 5. Nitrate isotope comparison with possible source groups according to (a) the method of KENDALL (1998) for groundwater samples of (b) the CMHI, (c) the RCK and (d) the DHYK areas. Figure 6. Correlation between the total mixing ratio and the nitrate mixing ra- tio for the three depression areas. Varicolored dashed lines indicate the regres- sion line of each correlation for each area. G eologia C roatica Taufiq et al.: Estimating Groundwater Mixing Ratios from Vertical Flux Processes due to Excessive Groundwater Pumping ... 181 p­>­0.05,­N­=­7).­­The­same­positive­correlation­was­found­in­all­ other­areas,­the­RCK­and­the­DHYK­areas,­but­with­lower­cor- relation­coefficients.­Nitrate­mixing­ratios­had­a­larger­standard­ error­(se­=­0.10-0.12)­than­the­total­mixing­ratios­(se­=­0.03-0.05)­ for­all­depression­areas­(Table­2).­The­total­mixing­ratio­shows­a­ better­fit­in­correlation­with­physical­parameters­than­the­nitrate­ mixing­ratio­does,­suggesting­that­nitrate­is­ineffective­as­a­pre- vailing­contaminant­tracer­in­this­basin.­It­might­be­because­ nitrate­in­deep­groundwater­were­controlled­by­many­factors.­ Therefore,­these­results­corroborate­the­findings­of­previous­work­ (RUEEDI­et­al.,­2005)­which­shows­that­estimations­using­all­ ­parameters­could­reduce­the­uncertainty.­ 6. CONCLUSIONS The­two­methods­for­calculating­mixing­ratios­were:­(1)­using­all­ the­parameters­and­(2)­using­only­nitrate,­presented­for­three­de- pression­areas­in­the­Bandung­basin­which­have­different­magni- tudes­of­groundwater­drawdown­(the­CMHI,­RCK,­and­DHYK­ areas).­The­values­for­total­mixing­ratios­indicate­that­mixing­be- tween­the­shallow­and­deep­groundwaters­clearly­occurs­in­all­ three­depression­areas,­but­with­different­ratios.­This­means­that­ the­mixing­processes­from­shallower­to­deeper­groundwater­oc- curred­in­areas­with­different­ratios­according­to­the­major­com- positions.­The­area­with­the­largest­drawdown­had­the­biggest­ value­of­the­total­mixing­ratio.­In­addition,­the­spatial­distribution­ map­of­total­mixing­ratios­clearly­shows­that­the­largest­ratio­oc- curs­near­the­centre­of­the­cone­of­depression,­and­decreases­ gradually­outwards­away­from­the­centre. A­positive­correlation­was­found­between­total­mixing­ratios,­ CFC-12­concentrations,­and­the­magnitude­of­vertical­flux.­This­ correlation­indicates­that­estimating­the­total­mixing­ratio­is­as­ effective­as­using­CFC-12­concentrations­and­vertical­flux­mo- deling­for­revealing­groundwater­mixing­caused­by­the­shallow­ groundwater­that­recharges­the­deep­groundwater.­Remarkably,­ the­highest­significant­correlation­is­found­between­the­correla- tion­of­the­total­mixing­ratio­and­magnitude­of­vertical­flux­in­the­ CMHI­area.­A­comparison­of­calculating­the­mixing­ratio­using­ all­the­parameters­and­using­nitrate­only­showed­a­less­positive­ correlation­thus­nitrate­is­an­ineffective­tracer­for­prevailing­con- taminants­for­deep­groundwaters­in­this­basin.­The­nitrate­mix- ing­ratio­also­has­a­larger­standard­error­than­the­result­of­total­ mixing­ratio,­therefore­these­results­show­that­estimations­using­ all­parameters­could­reduce­the­uncertainty.­Overall,­this­study­ concludes­that­the­method­of­total­mixing­ratio­using­all­chemi- cal­parameters­is­the­most­effective,­can­reduce­the­uncertainty­ and­is­consistent­with­the­method­using­physical­parameters. ACKNOWLEDGEMENT We­would­like­to­express­gratitude­to­emeritus­Professor­Dr.­Jun­ SHIMADA­(Kumamoto­University)­for­valuable­suggestions­and­ discussion.­ REFERENCES BAKORSOTANAL­(2009):­Land­use­map,­sub­Bandung­region,­scale­1:­50.000.­Agen- cy­of­geospatial­information:­Republic­of­Indonesia. BEYERLE,­U.,­AESCHBA,­C.H.,­HERTIG,­W.,­HOFER,­M.,­ IMBODEN,­D.M.,­ BAUR,­H.­&­KIPFER,­R.­(1999):­Infiltration­of­river­water­to­a­shallow­aquifer­ investigated­with­3H/3He,­noble­gases­and­CFCs.–­Journal­of­Hydrology,­220,­ 169–185. BÖHLKE,­J.K.,­WANTY,­R.,­TUTTLE,­M.,­DELIN,­G.­&­LANDON,­M.­(2002):­ Denitrification­in­the­recharge­area­and­discharge­area­of­a­transient­agricultural­ nitrate­plume­in­a­glacial­outwash­sand­aquifer,­Minnesota.–­Water­Resource­Re- search,­38,­10–26. BURNETT,­W.C,­PETERSON,­R.N,­SANTOS,­I.R.­&­HICKS,­R.W.­(2010):­Use­of­au- tomated­radon­measurements­for­rapid­assessment­of­groundwater­flow­into­Flo- rida­streams.–­Journal­of­Hydrology,­380,­Issues­3–4,­298–304.­doi:­10.1016/j. jhydrol.2009.11.005 CASCIOTTI,­K.L.,­SIGMAN,­D.M.,­GALANTER­H.M.,­BÖHLKE,­J.K.­&­HILKERT,­ A.­(2002):­Measurement­of­the­oxygen­isotopic­composition­of­nitrate­in­seawater­ and­freshwater­using­the­denitrifier­method.–­Analytical­Chemistry,­74,­4905–4912. FOSTER,­S.S.D.­&­CHILTON,­P.J.­ (2003):­Groundwater:­ the­process­ and­global­ significance­of­aquifer­degradation.­Philosophical­Transactions­of­the­Royal­Soci- ety­of­London.–­Biological­Sciences,­358,­1957–1972. HAN,­D.H.,­LIANG,­X.,­JIN,­M.G.,­CURRELL,­M.J.,­SONG,­X.F.­&­LIU,­C.M­(2010):­ Evaluation­of­groundwater­hydrochemical­characteristics­and­mixing­behavior­in­ the­Daying­and­Qicun­geothermal­systems,­Xinzhou­Basin.–­Journal­of­Volcanol- ogy­and­Geothermal­Research,­189,­92–104.­doi:­10.1016/j.jvolgeores.2009.10.011 HOSONO,­T.,­DELINOM,­R.,­NAKANO,­T.,­KAGABU,­M.,­&­SHIMADA,­J.­(2011):­ Evolution­model­of­δ34S­and­δ18O­in­dissolved­sulfate­in­volcanic­fan­aquifers­from­ recharge­to­coastal­zone­and­through­the­Jakarta­urban­area,­Indonesia.–­Science­ of­the­Total­Environment,­409,­2541–2554. HOSONO,­T.,­TOKUNAGA,­T.,­KAGABU,­M.,­NAKATA,­H.,­ORISHIKIDA,­T.,­LIN,­ I.­&­SHIMADA,­J­(2013):­The­use­of­δ15N­and­δ18O­tracers­with­an­understanding­ of­groundwater­flow­dynamics­for­evaluating­the­origins­and­attenuation­mecha- nisms­of­nitrate­pollution.–­Water­Research,­47,­2661–2675. HOSONO,­T.,­TOKUNAGA,­T.,­TSUSHIMAA,­A.­&­SHIMADA,­J.­(2014):­Combined­ use­of­δ13C,­δ15N,­and­δ34S­tracers­to­study­anaerobic­bacterial­processes­in­ground- water­flow­systems.–­Water­Research,­­54,­284–296. HUTASOIT,­L.M.­(2009):­Groundwater­condition­of­Bandung­area,­with­and­without­ artificial­recharge:­Numerical­simulation­results.–­Indonesian­Journal­on­Geosci- ence,­4,­1777–188­(In­Indonesian).­ JAGO-ON,­K.A.B.,­KANEKO,­S.,­FUJIKURA,­R.,­FUJIWARA,­A.,­IMAI,­T.,­MAT- SUMOTO,­T.,­ZHANG,­J.,­TANIKAWA,­H.,­TANAKA,­K,,­LEE,­B.,­&­TANI- GUCHI­M.­(2009):­Urbanization­and­subsurface­environmental­issues:­an­attempt­ at­DPSIR­model­application­in­Asian­cities.–­Science­of­the­Total­Environment,­ 407,­308–310.­doi:­10.1016/j.scitotenv.2008.08.004 KAPLAN,­N.­&­MAGARITZ,­M.­(1986):­A­nitrogen-isotope­study­of­the­sources­of­ nitrate­contamination­in­groundwater­of­the­Pleistocene­coastal­plain­aquifer,­Is- rael.–­Water­Research,­20,­131–135.­doi:­10.1016/0043-1354(86)90002-3 KENDALL,­C.­(1998):­Tracing­nitrogen­sources­and­cycling­in­catchments.–­In:­KEN- DALL,­C.­&­McDONNELL,­J.J.­(eds.):­Isotope­Tracers­in­Catchment­Hydrology.­ Elsevier.­Science­B.V.,­Amsterdam,­519–576.­doi:­10.1016/B978-0-444-81546- 0.50023-9 KREITLER,­C.W.­(1979):­Nitrogen-isotope­ratio­studies­of­soils­and­groundwater­nitrate­ from­alluvial­fan­aquifers­in­Texas.–­Journal­of­Hydrology,­42,­147–170. RUEEDI,­J.,­PURTSCHERT,­R.,­BEYERLE,­U.,­ALBERICH,­C.­&­KIPFER,­R.­(2005):­ Estimating­groundwater­mixing­ratios­and­their­uncertainties­using­a­statistical­ multi­parameter­approach.–­Journal­of­Hydrology,­305,­1–14.­doi:­10.1016/j.jhy- drol.2004.06.044 SIGMAN,­D.M.,­CASCIOTTI,­K.L.,­ANDREANI,­M.,­BARFORD,­C.,­GALANTER,­ M.­&­BÖHLKE,­J.K.­(2001):­A­bacterial­method­for­the­nitrogen­isotopic­analysis­ of­nitrate­in­seawater­and­freshwater.–­Analytical­Chemistry,­73,­145–153.­doi:­ 10.1021/ac010088e SINGLETON,­M.J.,­ESSER,­B.K.,­MORAN,­J.E.,­HUDSON,­G.B.,­MCNAB,­W.W.­&­ HARTER,­T.­(2007):­Saturated­zone­denitrification:­potential­for­natural­attenua- tion­of­nitrate­contamination­in­shallow­groundwater­under­dairy­operations.–­En- vironmental­Science­and­Technology,­41,­759–765.­doi:­10.1021/es061253g TANIGUCHI,­M.,­SHIMADA,­J.,­FUKUDA,­Y.,­YAMANO,­M.,­ONODERA,­S.,­ KANEKO,­S.­&­YOSHIKOSHI,­A.­(2009):­Anthropogenic­effects­on­the­subsur- face­thermal­and­groundwater­environments­in­Osaka,­Japan­and­Bangkok,­Thai- land.–­Science­of­the­Total­Environment,­407,­3153–3164.­doi:­10.1016/j.scito- tenv.2008.06.064 TAUFIQ,­A.,­HOSONO,­T.,­IDE,­K.,­KAGABU­M.,­ISKANDAR,­I.,­EFFENDI A.J.,­ HUTASOIT, L.M.­&­SHIMADA,­J.­(2017):­Impact­of­excessive­groundwater­ pumping­on­rejuvenation­age­processes­in­the­Bandung­basin,­Indonesia­as­deter- mined­by­hydrogeochemistry­and­modeling.–­Hydrogeology­Journal,­26,­1263– 1279.­doi:­10.1007/s10040-017-1696-8 TAUFIQ,­­A.,­ ­EFFENDI,­­A.J.,­ ­ISKANDAR,­­I.,­­HOSONO,­­T.­­&­­HUTASOIT,­ ­L.M.­ (2018):­­Controlling­Factors­­and­­Driving­Mechanisms­Nitrate­­Contamination­­in­ Groundwater­­System­of­­Bandung­­Basin­,­Indonesia,­deduced­by­combined­use­of­ stable­isotope­ratios,­CFC­age­dating,­and­socioeconomic­parameters.–­Water­ ­Research­­Journal.­https://doi.org/10.1016/j.watres.2018.10.049­(article­in­press). WAGNER,­W.­&­SUKRISNO,­X.­(1998):­Natural­groundwater­quality­and­groundwater­ contamination­in­the­Bandung­basin,­Indonesia.–­Indonesia­Bulletin­of­Environ- mental­geology,­23. WIRAKUSUMAH,­A.D.­&­DANARYANTO,­H.­(2004):­Groundwater­management­in­ Indonesia­Case­Study:­Groundwater­conservation­in­Jakarta,­Bandung­and­Sema- rang.­41st­Coordinating­Committee­for­Geoscience­Programmes­in­East­and­South- east­Asia­(CCOP)­(Tsukuba,­Japan). G eo lo gi a C ro at ic a Geologia Croatica 71/3182 a)­Shallow­groundwater­ 1.1­CMHI­area Ca2+ Mg2+ Na+ K+ HCO3 - Cl- SO4 - δ18O δ2H DO ORP δ18ONO3 δ15NNO3 (1)­Fe (2)­Mn (3)­CFC-12 (4)­NO3 - mg/l mg/l mg/l mg/l mg/l mg/l mg/l (0/00) (0/00) mV (0/00) (0/00) ppb ppb pptv mg/l 7 75.50 9.10 16.70 8.15 276.67 5.80 90.15 -5.26 -43.97 4.28 85.00 5.7 10.2 0.99 0.19 502 3.99 end­member­1 1 38.22 11.05 42.26 10.63 277.38 20.24 9.00 -5.16 -42.97 4.86 90.00 2.0 21.6 7.29 0.23 249 5.04 contaminated­(4) 2 38.10 11.00 42.44 10.67 278.66 20.44 8.70 -5.16 -42.97 3.73 90.00 9.7 22.8 10.85 17.49 437 5.04 contaminated­(4) 3 38.89 12.24 46.78 6.54 227.16 13.49 41.77 -5.31 -43.51 4.11 95.75 -12.2 15.8 6.92 11.40 230 12.09 contaminated­(4) 31 55.11 15.45 28.22 11.66 176.23 77.45 103.60 -5.46 -44.89 5.66 100.00 19.9 14.3 1.41 0.37 164 4.00 contaminated­(4) 9 51.13 18.09 23.87 9.44 121.08 44.08 87.21 -6.91 -42.83 5.01 84.00 -1.5 9.6 2.30 0.59 768 10.43 contaminated­(3.4) 28 42.00 16.73 60.21 9.87 176.23 47.22 1.39 -4.20 -38.43 1.92 26.40 3.4 9.0 4 51.00 18.12 23.98 9.50 121.1 44.35 87.20 -6.91 -42.83 5.77 191.00 -1.5 9.6 2.62 19.32 769 2.28 contaminated­(3) 5 65.10 25.45 27.53 11.45 176.35 77.57 104.71 -5.40 -35.00 6.67 102.00 2.4 11.0 1.43 0.33 579 9.97 contaminated­(3) 27 61.10 25.45 37.44 11.40 176.33 77.12 104.23 -5.40 -35.00 4.72 207.00 1.3 7.1 0.97 3.91 595 3.95 contaminated­(3) 13 56.60 18.54 76.08 34.43 371.45 91.06 32.51 -5.35 -45.00 2.08 116.00 3.1 9.3 2.54 6.48 40 4.78 contaminated­(4) 1.2­RCK­area Ca2+ Mg2+ Na+ K+ HCO3 - Cl- SO4 - δ18O δ2H DO ORP δ18ONO3 δ15NNO3 (1)­Fe (2)­Mn (3)­CFC-12 (4)­NO3 - mg/l mg/l mg/l mg/l mg/l mg/l mg/l (0/00) (0/00) mV (0/00) (0/00) ppb ppb pptv mg/l 30a 55.52 14.47 48.05 13.50 310.20 16.80 29.21 -6.23 -48.49 4.70 99.51 8.1 14.4 63.60 1.49 21 1.08 12 53.82 17.82 61.17 8.96 283.58 33.46 34.28 -4.87 -41.83 3.90 130.00 33.1 12.0 4.16 5.60 12 2.97 end­member­1 30 55.57 14.85 48.38 13.63 310.86 16.75 29.16 -6.22 -48.47 3.97 147.79 3.37 1.69 20.69 contaminated­(4) 29 53.43 17.59 61.67 8.93 283.96 33.79 34.60 -5.01 -43.21 3.21 132.74 17.9 39.1 1.15 1.68 7.62 contaminated­(4) 26 53.99 17.60 58.06 8.80 283.76 33.50 34.66 -4.88 -41.84 0.00 3.6 7.3 0.40 0.23 1.06 20 55.52 14.47 48.05 13.50 310.20 16.80 29.21 -6.22 -48.47 3.71 173.00 8.1 14.4 3.65 26.37 21 1.08 24 53.90 17.60 61.06 8.90 283.80 33.42 34.45 -5.53 -47.98 4.24 174.00 5.2 19.5 0.00 0.09 12 1.97 21a 19.60 10.98 60.10 5.75 251.89 52.30 1.84 -4.87 -41.83 6.61 90.00 15.0 12.1 6.79 58 1.25 23 58.20 22.80 69.70 16.40 385.80 91.20 18.90 -3.94 -41.48 2.47 87.00 18.2 47.0 1.04 4.67 56 1.65 16 61.20 19.71 89.39 27.20 423.13 111.29 24.52 -4.92 -41.46 4.16 107.00 15.4 21.0 70.79 9.52 85 5.75 contaminated­(4) 13 56.60 18.54 76.08 34.43 371.45 91.06 32.51 -5.35 -45.00 2.08 116.00 3.1 9.3 2.54 6.48 40 4.78 contaminated­(4) 1.3­DHYK­area Ca2+ Mg2+ Na+ K+ HCO3 - Cl- SO4 - δ18O δ2H DO ORP δ18ONO3 δ15NNO3 (1)­Fe (2)­Mn (3)­CFC-12 (4)­NO3 - mg/l mg/l mg/l mg/l mg/l mg/l mg/l (0/00) (0/00) mV (0/00) (0/00) ppb ppb pptv mg/l 15d 45.17 18.75 31.91 10.21 290.50 20.90 21.80 115 5.0 10.8 0.54 0.23 692.75 2.25 contaminated­(3) 6 55.10 15.45 28.31 11.66 176.23 77.45 104.90 -6.30 -44.07 3.7 124 5.5 12.9 0.00 1.06 327.29 3.87 contaminated­(4) 6a 62.04 23.14 31.05 6.35 168.44 86.60 43.31 -5.53 -39.00 5.2 192 4.5 16.9 45.73 1.99 9.06 3.42 contaminated­(4) 9 51.13 18.09 23.87 9.44 121.08 44.08 87.21 -5.91 -42.83 5.0 84 -1.5 9.6 2.30 0.59 767.92 10.43 contaminated­(3.4) 19 62.40 23.10 30.30 6.50 168.33 86.50 43.30 -4.49 -29.75 3.5 90 1.4 -1.2 0.21 0.10 250.33 3.33 contaminated­(4) 28 42.00 16.73 60.21 9.87 176.23 47.22 1.39 -4.20 -38.43 1.9 26 3.4 9.0 699.41 532.13 1.30 contaminated­(2) 18 55.01 15.34 29.11 11.41 176.98 77.30 104.60 -5.30 -44.07 3.5 125 5.5 12.9 0.01 0.64 1132.00 3.87 contaminated­(3,4) 31 17.65 6.55 11.70 3.52 130.20 4.10 9.60 -5.60 -35.61 4.6 125 0.67 0.14 1276.19 3.00 contaminated­(3,4) 10 76.64 9.17 16.99 8.18 280.69 6.00 90.10 -6.17 -46.77 4.0 68 25.2 30.5 0.72 1.62 646.69 1.67 contaminated­(3) 11 52.40 15.48 27.39 10.31 248.09 12.00 49.65 -5.19 -42.70 2.9 82 1.0 10.5 2.52 6.28 192.67 2.99 end­member­1 11a 52.50 15.45 27.10 10.31 247.89 11.00 49.50 -5.19 -42.70 1.8 162 6.4 18.7 18.36 144.18 646.69 9.02 contaminated­(3) Elevated­substances Note Sampling­No­ (Sx) 7­Major­ions Note Sampling­No­ (Sx) 7­Major­ions 2­Stable­isotopes Insitu­test Nitrate isotopes Elevated­substances Sampling­No­ (Sx) 7­Major­ions 2­Stable­isotopes Insitu­test Nitrate isotopes 2­Stable­isotopes Insitu­test Nitrate isotopes Elevated­substances Note b)­Deep­groundwater Ca2+ Mg2+ Na+ K+ HCO3 - Cl- SO4 - δ18O δ2H DO ORP δ18ONO3 δ15NNO3 (3)­CFC-12 (4)­NO3 - mg/l mg/l mg/l mg/l mg/l mg/l mg/l (0/00) (0/00) mV (0/00) (0/00) pptv mg/l 10 60.2 23.2 33.5 8.7 280.9 21.2 13.8 -6.2 -46.8 4.1 79.0 20.7 16.5 405.2 1.3 1 23.8 10.7 16.9 7.8 184.7 4.0 8.6 -5.5 -44.2 3.8 92.0 38.0 28.7 0.0 1.6 9 59.9 22.9 32.6 7.5 275.2 20.8 12.7 -5.4 -38.3 2.1 51.2 20.7 16.5 0.0 1.4 2 28.0 13.0 24.0 9.3 219.2 9.8 14.5 -6.2 -46.6 5.2 25.5 321.6 1.1 contaminated­(1) 5a 28.8 12.8 23.8 9.3 217.4 8.8 14.5 -6.2 -45.6 2.5 48.1 15.6 18.4 0.0 3.0 contaminated­(4) 3 27.9 13.9 23.9 9.2 217.9 9.8 15.2 -5.6 -44.8 2.1 66.9 129.5 1.1 contaminated­(1) 5 68.1 26.7 86.3 14.9 295.7 104.6 54.0 -5.9 -45.5 4.3 39.3 15.4 18.0 314.7 1.9 contaminated­(1) 8 59.9 23.1 32.5 7.4 279.5 20.9 13.4 -5.5 -44.2 2.1 96.0 38.0 28.7 0.0 4.0 contaminated­(4) 6c 43.9 18.9 30.9 9.9 288.4 21.7 21.9 -5.7 -44.7 2.3 75.7 186.3 1.2 contaminated­(1) 6 57.0 24.1 63.1 11.5 206.7 45.2 25.2 -4.7 -39.9 2.1 -10.8 13.6 19.8 292.7 3.2 contaminated­(1,­4) 4 29.0 13.2 24.9 9.5 219.4 10.0 15.5 -6.1 -46.5 3.4 31.2 21.2 16.5 243.0 1.1 contaminated­(1) 4a 55.8 23.8 62.5 10.9 205.4 44.2 24.1 -6.1 -46.5 3.0 -68.5 21.4 16.1 0.0 1.1 6b 45.2 19.3 32.6 10.5 290.5 21.9 22.4 -5.6 -44.6 5.8 61.3 117.9 1.2 contaminated­(1) 6a 44.9 19.2 31.9 10.2 289.8 20.7 21.9 -5.6 -44.6 1.9 71.9 80.0 0.2 contaminated­(1) 7c 45.2 18.8 32.6 10.5 290.5 21.9 22.4 -6.1 -46.3 2.7 17.0 -4.8 -2.7 169.2 5.3 contaminated­(1,­4) 7 60.8 21.0 73.6 11.2 386.9 31.8 98.1 -5.9 -40.7 3.0 -60.4 20.0 13.0 143.1 4.1 contaminated­(1,­4) 7b 60.1 24.0 33.7 9.9 285.8 21.9 13.8 -6.0 -40.8 2.7 14.0 11.9 16.5 126.6 3.6 contaminated­(1,­4) 7a 60.6 20.8 72.9 11.1 385.1 30.4 97.9 -5.9 -40.8 6.3 -44.1 20.7 18.0 86.7 3.6 contaminated­(1,­4) 47 25.1 11.1 31.6 8.9 253.5 4.0 4.0 -6.5 -45.5 2.8 124.6 6.6 8.9 23.2 0.4 contaminated­(1) 46 24.8 11.1 31.2 8.9 250.8 3.9 5.9 -6.0 -45.5 3.2 110.0 20.1 12.6 0.0 0.2 end­member­2 45 60.8 13.0 73.7 10.9 388.5 32.0 90.8 -6.2 -45.6 2.8 -30.3 21.2 19.1 0.0 1.7 12 37.9 19.7 22.0 10.5 305.2 7.8 9.1 -6.0 -46.7 3.1 38.7 8.9 18.0 2.8 12d 39.0 18.7 23.1 11.8 280.7 8.6 9.3 -4.6 -38.3 2.0 -32.0 0.0 3.0 contaminated­(4) 12f 38.9 19.9 22.9 12.0 299.9 8.1 9.2 -5.4 -42.5 2.3 -60.4 33.7 38.3 0.0 3.0 contaminated­(4) 1 37.2 15.7 25.0 8.9 267.8 2.0 4.6 -5.4 -42.5 4.3 64.4 0.0 3.0 contaminated­(4) 15 79.3 34.6 188.3 18.6 583.3 141.3 1.6 -5.5 -44.9 3.5 -14.0 -1.5 6.0 255.3 0.2 contaminated­(1) 15a 23.8 8.9 78.7 9.1 302.8 43.8 2.7 -6.8 -44.0 2.4 31.2 116.6 2.6 contaminated­(1) 34 23.3 8.6 75.5 9.1 300.7 42.6 2.6 -6.0 -42.6 2.3 -60.4 18.9 12.4 0.0 0.4 39b 24.2 9.6 78.5 8.8 302.7 43.4 2.5 -6.5 -42.2 3.2 50.6 8.5 25.8 0.0 2.5 Data­sources:­­major­ion,­stable­isotopes­and­insitu­test­data­(TAUFIQ­et.­al.,­2017);­Fe2+,­Mn2+­and­nitrate­isotopes­(this­study).­ 2.1­CMHI­area Sampling­No­ (Dx) 7­Major­ions 2­Stable­isotopes Insitu­test Nitrate isotopes elevated­contaminants Note Appendix 1. Data of all parameters for shallow and deep groundwater with their identified elevated substances G eologia C roatica Taufiq et al.: Estimating Groundwater Mixing Ratios from Vertical Flux Processes due to Excessive Groundwater Pumping ... 183 Ca2+ Mg2+ Na+ K+ HCO3 - Cl- SO4 - δ18O δ2H DO ORP δ18ONO3 δ15NNO3 (3)­CFC-12 (4)­NO3 - mg/l mg/l mg/l mg/l mg/l mg/l mg/l (0/00) (0/00) mV (0/00) (0/00) pptv mg/l 23 21.5 8.3 10.5 2.3 157.2 2.0 3.2 -6.2 -51.5 4.3 147.2 6.4 12.9 3.2 contaminated­(4) 22a 39.2 9.2 13.5 5.0 160.8 0.6 1.1 -6.1 -41.0 5.3 130.9 34.6 40.8 120.7 2.0 contaminated­(1) 22 39.9 7.4 6.9 3.0 110.6 2.7 0.5 -6.3 -50.8 5.6 124.0 5.4 12.2 302.1 4.0 contaminated­(1,­4) 21 39.2 9.3 13.6 5.0 170.4 0.7 1.2 -6.3 -51.1 5.3 171.0 3.6 8.2 100.3 2.1 contaminated­(1) 33a 36.1 15.5 48.9 6.3 275.9 44.2 8.1 -5.8 -48.4 3.7 18.0 19.7 15.2 234.8 0.4 contaminated­(1) 25 36.3 14.9 48.2 6.5 280.1 44.1 8.7 -6.0 -48.9 5.5 134.6 3.8 5.7 238.4 0.5 contaminated­(1) 20 33.2 25.0 55.6 13.6 375.4 42.6 0.8 -5.4 -45.8 4.0 99.5 5.2 11.4 48.3 2.0 contaminated­(1) 24 25.2 14.1 16.8 7.1 233.1 1.3 6.4 -6.1 -48.8 3.2 132.7 4.7 8.7 11.7 0.5 contaminated­(1) 24b 25.2 14.1 16.1 7.1 230.2 1.2 6.3 -5.4 -45.8 4.0 159.0 5.2 11.4 105.7 0.2 contaminated­(1) 19c 38.0 18.1 50.8 7.8 298.3 60.7 0.6 -5.5 -47.0 2.2 5.0 18.6 14.6 68.1 0.3 contaminated­(1) 18a 46.5 19.2 110.5 9.1 375.4 121.7 2.7 -4.5 -42.8 4.4 -6.0 19.8 16.2 27.9 0.2 contaminated­(1) 20a 36.1 16.3 49.8 6.5 278.0 44.9 8.3 -5.8 -48.4 3.2 45.6 6.8 10.4 38.6 0.6 contaminated­(1) 19 27.1 11.5 63.6 9.3 321.6 23.5 0.3 -6.0 -41.7 3.3 8.0 18.6 14.6 156.8 0.3 contaminated­(1) 33 36.2 15.7 47.4 6.2 270.5 40.3 8.3 -5.8 -48.4 3.7 105.0 15.8 5.1 39.1 0.1 contaminated­(1) 27 42.4 19.9 30.2 5.7 323.4 26.0 2.0 -4.5 -42.8 7.0 -30.0 18.6 12.5 0.0 0.1 end­member­2 18 47.3 19.4 111.5 9.2 379.0 123.8 2.8 -5.1 -45.4 5.6 -15.2 10.4 16.5 0.0 0.2 19b 36.3 20.5 57.1 19.8 612.6 94.4 1.6 -6.1 -41.0 2.5 2.0 23.2 16.7 1.6 Ca2+ Mg2+ Na+ K+ HCO3 - Cl- SO4 - δ18O δ2H DO ORP δ18ONO3 δ15NNO3 (3)­CFC-12 (4)­NO3 - mg/l mg/l mg/l mg/l mg/l mg/l mg/l (0/00) (0/00) mV (0/00) (0/00) pptv mg/l 11 27.5 13.2 18.2 8.4 126.7 40.5 14.0 -6.1 -46.6 3.0 100.0 18.5 13.4 0.0 2.0 12 37.9 19.7 22.0 10.5 305.2 7.8 9.1 -6.0 -46.7 3.1 72.0 8.9 18.0 2.8 12a 38.8 19.9 22.3 11.9 305.5 8.0 9.1 -4.6 -38.3 3.1 38.7 3.0 contaminated­(4) 12d 39.0 18.7 23.1 11.8 280.7 8.6 9.3 -4.6 -38.3 2.0 -32.0 0.0 3.0 contaminated­(4) 12f 38.9 19.9 22.9 12.0 299.9 8.1 9.2 -5.4 -42.5 2.3 -60.4 33.7 38.3 0.0 3.0 contaminated­(4) 17 24.4 9.6 79.5 9.2 304.9 43.8 2.7 -5.5 -49.0 2.0 -32.0 20.1 17.8 46.0 2.6 contaminated­(1) 13 79.1 34.5 187.1 18.5 580.1 140.5 1.5 -5.8 -44.7 2.9 -5.2 0.0 3.8 contaminated­(4) 29a 16.2 7.4 162.7 22.6 395.7 40.5 6.4 -5.6 -43.8 2.0 0.0 19.4 21.3 1.3 29 16.2 7.5 162.6 22.6 395.0 40.2 6.2 -5.6 -43.8 5.0 -19.6 285.1 1.1 contaminated­(1) 30a 30.6 11.6 35.3 7.0 295.9 2.0 4.8 -5.7 -44.0 3.0 -42.2 20.1 13.4 0.0 0.9 end­member­2 43 38.2 15.2 99.8 11.3 324.3 74.4 1.8 -5.8 -40.7 3.9 -38.7 19.4 21.7 0.0 6.6 contaminated­(4) 28 33.2 13.5 53.1 10.3 308.5 27.0 6.4 -5.5 -42.9 3.5 -39.7 0.0 6.6 contaminated­(4) 28a 32.9 13.4 52.8 10.1 304.6 24.6 6.0 -4.6 -42.9 2.8 -13.0 14.2 20.2 0.0 5.7 contaminated­(4) 41 26.8 15.1 88.8 11.3 320.2 73.8 1.8 -6.0 -40.6 3.3 64.4 15.2 20.8 0.0 2.4 42 29.1 16.8 95.9 11.6 330.5 74.7 1.8 -5.5 -42.5 4.0 -42.2 -8.2 5.8 130.5 2.4 contaminated­(1) 32 30.2 15.2 89.9 11.5 324.4 74.2 1.9 -5.0 -42.9 3.0 -42.2 16.4 21.4 98.2 7.8 contaminated­(1,­4) 30 30.1 15.1 89.8 11.4 324.3 73.8 2.0 -5.7 -44.0 4.9 -5.2 16.1 20.1 269.5 7.4 contaminated­(1,­4) 31a 28.2 17.9 54.0 10.7 268.4 18.5 9.3 -5.4 -43.3 4.7 -5.2 16.4 21.4 225.0 2.4 contaminated­(1) 40 31.2 15.2 97.9 12.4 326.8 75.2 1.8 -5.3 -40.7 2.9 -13.0 16.8 8.0 17.7 5.7 contaminated­(1,­4) 31 44.4 18.7 31.8 10.2 288.9 20.7 21.7 -5.9 -42.9 3.1 150.0 -8.4 7.2 363.8 1.1 contaminated­(1) 44 44.1 18.6 31.9 10.1 289.5 18.9 20.9 -6.1 -46.5 3.0 188.0 -6.2 9.2 300.6 1.1 contaminated­(1) Data­sources:­­major­ion,­stable­isotopes­and­insitu­test­data­(TAUFIQ­et.­al.,­2017);­Fe2+,­Mn2+­and­nitrate­isotopes­(this­study).­ 2.2­RCK­area Sampling­No­ (Dx) 7­Major­ions 2­Stable­isotopes Insitu­test Nitrate isotopes elevated­contaminants Note 2.3­DHYK­area Sampling­No­ (Dx) 7­Major­ions 2­Stable­isotopes Insitu­test Nitrate isotopes elevated­contaminants Note a)­CMHI­area Total­ mixing ratio mg/l mp mg/l mp mg/l mp mg/l mp mg/l mp mg/l mp mg/l mp (0/00) mp (0/00) mp m 10 60.2 -0.04 23.2 -2.62 33.5 0.71 8.7 0.81 280.9 0.96 21.2 0.41 13.8 0.13 -6.2 -0.03 -46.8 -0.69 0.69 1 23.8 -2.52 10.7 0.59 16.9 1.00 7.8 1.13 184.7 1.82 4.0 1.06 8.6 0.07 -5.5 0.78 -44.2 0.86 0.37 9 59.9 -0.06 22.9 -2.54 32.6 0.72 7.5 1.24 275.2 1.01 20.8 0.42 12.7 0.12 -5.4 0.84 -38.3 4.41 0.69 2 28.0 -2.23 13.0 0.01 24.0 0.87 9.3 0.58 219.2 1.51 9.8 0.84 14.5 0.14 -6.2 0.01 -46.6 -0.56 0.37 5a 28.8 -2.18 12.8 0.05 23.8 0.88 9.3 0.57 217.4 1.53 8.8 0.88 14.5 0.14 -6.2 0.01 -45.6 0.00 0.39 3 27.9 -2.24 13.9 -0.22 23.9 0.87 9.2 0.63 217.9 1.53 9.8 0.84 15.2 0.14 -5.6 0.61 -44.8 0.49 0.37 5 68.1 0.49 26.7 -3.51 86.3 -0.22 14.9 -1.44 295.7 0.83 104.6 -2.75 54.0 0.59 -5.9 0.33 -45.5 0.11 0.30 8 59.9 -0.06 23.1 -2.59 32.5 0.72 7.4 1.26 279.5 0.98 20.9 0.42 13.4 0.12 -5.5 0.78 -44.2 0.86 0.69 6c 43.9 -1.15 18.9 -1.51 30.9 0.75 9.9 0.36 288.4 0.90 21.7 0.39 21.9 0.22 -5.7 0.53 -44.7 0.58 0.49 6 57.0 -0.26 24.1 -2.84 63.1 0.19 11.5 -0.20 206.7 1.63 45.2 -0.50 25.2 0.26 -4.7 1.60 -39.9 3.45 0.48 4 29.0 -2.17 13.2 -0.05 24.9 0.86 9.5 0.53 219.4 1.51 10.0 0.83 15.5 0.15 -6.1 0.05 -46.5 -0.52 0.38 4a 55.8 -0.34 23.8 -2.77 62.5 0.20 10.9 0.01 205.4 1.64 44.2 -0.46 24.1 0.25 -6.1 0.03 -46.5 -0.53 0.47 6b 45.2 -1.06 19.3 -1.60 32.6 0.72 10.5 0.14 290.5 0.88 21.9 0.38 22.4 0.23 -5.6 0.62 -44.6 0.60 0.50 6a 44.9 -1.08 19.2 -1.59 31.9 0.73 10.2 0.25 289.8 0.88 20.7 0.43 21.9 0.22 -5.6 0.59 -44.6 0.60 0.50 7c 45.2 -1.06 18.8 -1.49 32.6 0.72 10.5 0.14 290.5 0.88 21.9 0.38 22.4 0.23 -6.1 0.03 -46.3 -0.41 0.50 7 60.8 0.00 21.0 -2.04 73.6 0.00 11.2 -0.11 386.9 0.01 31.8 0.01 98.1 1.09 -5.9 0.26 -40.7 2.96 0.58 7b 60.1 -0.05 24.0 -2.82 33.7 0.70 9.9 0.36 285.8 0.92 21.9 0.38 13.8 0.13 -6.0 0.24 -40.8 2.92 0.68 7a 60.6 -0.02 20.8 -2.00 72.9 0.01 11.1 -0.07 385.1 0.03 30.4 0.06 97.9 1.09 -5.9 0.28 -40.8 2.92 0.59 47 25.1 -2.43 11.1 0.48 31.6 0.74 8.9 0.72 253.5 1.21 4.0 1.06 4.0 0.02 -6.5 -0.38 -45.5 0.11 0.33 46 24.8 -2.45 11.1 0.49 31.2 0.75 8.9 0.73 250.8 1.23 3.9 1.06 5.9 0.04 -6.0 0.17 -45.5 0.07 0.32 45 60.8 0.00 13.0 0.00 73.7 0.00 10.9 0.00 388.5 0.00 32.0 0.00 90.8 1.01 -6.2 0.01 -45.6 0.00 0.57 12 37.9 -1.56 19.7 -1.72 22.0 0.91 10.5 0.15 305.2 0.74 7.8 0.92 9.1 0.07 -6.0 0.14 -46.7 -0.63 0.49 12d 39.0 -1.48 18.7 -1.45 23.1 0.89 11.8 -0.33 280.7 0.96 8.6 0.89 9.3 0.08 -4.6 1.72 -38.3 4.39 0.50 12f 38.9 -1.49 19.9 -1.77 22.9 0.89 12.0 -0.40 299.9 0.79 8.1 0.91 9.2 0.07 -5.4 0.85 -42.5 1.87 0.50 1 37.2 -1.61 15.7 -0.70 25.0 0.85 8.9 0.73 267.8 1.08 2.0 1.14 4.6 0.02 -5.4 0.85 -42.5 1.87 0.51 15 79.3 1.26 34.6 -5.53 188.3 -2.01 18.6 -2.80 583.3 -1.74 141.3 -4.14 1.6 -0.01 -5.5 0.78 -44.9 0.45 0.10 15a 23.8 -2.52 8.9 1.05 78.7 -0.09 9.1 0.66 302.8 0.77 43.8 -0.45 2.7 0.00 -6.8 -0.74 -44.0 1.01 0.01 34 23.3 -2.55 8.6 1.12 75.5 -0.03 9.1 0.65 300.7 0.79 42.6 -0.40 2.6 0.00 -6.0 0.22 -42.6 1.81 0.00 39b 24.2 -2.49 9.6 0.87 78.5 -0.08 8.8 0.76 302.7 0.77 43.4 -0.43 2.5 0.00 -6.5 -0.42 -42.2 2.04 0.00 Sampling­ No Ca2+ Mg2+ Na+ K+ Cl- SO4 - δ18O δ2HHCO3 - Appendix 2. Calculation results of total mixing ratio. Appendix 1. Continuation. G eo lo gi a C ro at ic a Geologia Croatica 71/3184 b)­RCK­area Total­ mixing ratio mg/l mp mg/l mp mg/l mp mg/l mp mg/l mp mg/l mp mg/l mp (0/00) mp (0/00) mp m 23 21.5 -1.86 8.3 5.68 10.5 3.66 2.3 -1.06 157.2 4.17 2.0 -3.23 3.2 0.04 -6.2 4.44 -51.5 -9.33 0.17 22a 39.2 -0.29 9.2 5.25 13.5 3.51 5.0 -0.22 160.8 4.08 0.6 -3.43 1.1 -0.03 -6.1 4.18 -41.0 1.87 0.12 22 39.9 -0.22 7.4 6.12 6.9 3.85 3.0 -0.85 110.6 5.34 2.7 -3.14 0.5 -0.05 -6.3 4.53 -50.8 -8.49 0.10 21 39.2 -0.29 9.3 5.18 13.6 3.50 5.0 -0.22 170.4 3.84 0.7 -3.41 1.2 -0.02 -6.3 4.55 -51.1 -8.81 0.12 33a 36.1 -0.56 15.5 2.14 48.9 1.64 6.3 0.18 275.9 1.19 44.2 2.45 8.1 0.19 -5.8 3.34 -48.4 -5.97 0.25 25 36.3 -0.54 14.9 2.44 48.2 1.68 6.5 0.23 280.1 1.09 44.1 2.43 8.7 0.21 -6.0 3.80 -48.9 -6.50 0.27 20 33.2 -0.82 25.0 -2.53 55.6 1.29 13.6 2.44 375.4 -1.31 42.6 2.23 0.8 -0.04 -5.4 2.36 -45.8 -3.20 0.03 24 25.2 -1.52 14.1 2.86 16.8 3.33 7.1 0.43 233.1 2.27 1.3 -3.33 6.4 0.14 -6.1 4.01 -48.8 -6.39 0.25 24b 25.2 -1.53 14.1 2.83 16.1 3.37 7.1 0.43 230.2 2.34 1.2 -3.34 6.3 0.13 -5.4 2.36 -45.8 -3.20 0.25 19c 38.0 -0.40 18.1 0.87 50.8 1.55 7.8 0.63 298.3 0.63 60.7 4.67 0.6 -0.04 -5.5 2.63 -47.0 -4.48 0.02 18a 46.5 0.36 19.2 0.32 110.5 -1.59 9.1 1.05 375.4 -1.31 121.7 12.87 2.7 0.02 -4.5 0.00 -42.8 0.00 0.00 20a 36.1 -0.56 16.3 1.74 49.8 1.60 6.5 0.23 278.0 1.14 44.9 2.55 8.3 0.19 -5.8 3.29 -48.4 -5.97 0.25 19 27.1 -1.36 11.5 4.10 63.6 0.87 9.3 1.11 321.6 0.04 23.5 -0.35 0.3 -0.05 -6.0 3.72 -41.7 1.12 0.03 33 36.2 -0.55 15.7 2.04 47.4 1.72 6.2 0.15 270.5 1.33 40.3 1.92 8.3 0.20 -5.8 3.25 -48.4 -5.98 0.26 27 42.43 0.00 19.85 0.00 80.24 0.00 5.72 0.00 323.41 0.00 26.03 0.00 2.00 0.00 -4.47 0.00 -42.77 0.00 0.10 18 47.3 0.43 19.4 0.23 111.5 -1.65 9.2 1.07 379.0 -1.40 123.8 13.16 2.8 0.02 -5.1 1.50 -45.4 -2.84 0.00 19b 36.3 -0.55 20.5 -0.32 57.1 1.22 19.8 4.36 612.6 -7.26 94.4 9.21 1.6 -0.01 -6.1 4.18 -41.0 1.87 0.00 c)­DHYK­area Total­ mixing ratio mg/l mp mg/l mp mg/l mp mg/l mp mg/l mp mg/l mp mg/l mp (0/00) mp (0/00) mp m 11 27.5 -0.75 13.2 -5.97 18.2 1.13 8.4 2.90 126.7 2.59 40.5 0.50 14.0 0.25 -6.1 -0.47 -46.6 2.97 0.31 12 37.9 -0.02 19.7 13.79 22.0 1.07 10.5 0.81 305.2 0.25 7.8 0.97 9.1 0.15 -6.0 -0.33 -46.7 3.00 0.23 12a 38.8 0.04 19.9 14.36 22.3 1.07 11.9 -0.61 305.5 0.25 8.0 0.97 9.1 0.15 -4.6 1.97 -38.3 -1.20 0.23 12d 39.0 0.06 18.7 10.67 23.1 1.06 11.8 -0.51 280.7 0.57 8.6 0.96 9.3 0.16 -4.6 1.97 -38.3 -1.20 0.24 12f 38.9 0.05 19.9 14.39 22.9 1.06 12.0 -0.70 299.9 0.32 8.1 0.97 9.2 0.15 -5.4 0.66 -42.5 0.91 0.23 17 24.4 -0.97 9.6 -16.73 79.5 0.28 9.2 2.11 304.9 0.25 43.8 0.45 2.7 0.02 -5.5 0.45 -49.0 4.14 0.04 13 79.1 2.88 34.5 58.48 187.1 -1.21 18.5 -7.22 580.1 -3.36 140.5 -0.97 1.5 -0.01 -5.8 0.05 -44.7 2.01 0.10 29a 16.2 -1.55 7.4 -23.39 162.7 -0.87 22.6 -11.45 395.7 -0.94 40.5 0.50 6.4 0.10 -5.6 0.37 -43.8 1.54 0.05 29 16.2 -1.55 7.5 -23.33 162.6 -0.87 22.6 -11.41 395.0 -0.93 40.2 0.50 6.2 0.09 -5.6 0.36 -43.8 1.55 0.04 30a 30.6 -0.54 11.6 -10.64 35.3 0.89 7.0 4.32 295.9 0.37 2.0 1.06 4.8 0.06 -5.7 0.12 -44.0 1.64 0.14 43 38.2 0.00 15.2 0.00 99.8 0.00 11.3 0.00 324.3 0.00 74.4 0.00 1.8 0.00 -5.8 0.01 -40.7 0.00 0.00 28 33.2 -0.35 13.5 -4.97 53.1 0.65 10.3 1.02 308.5 0.21 27.0 0.69 6.4 0.10 -5.5 0.45 -42.9 1.09 0.14 28a 32.9 -0.37 13.4 -5.30 52.8 0.65 10.1 1.21 304.6 0.26 24.6 0.73 6.0 0.09 -4.6 2.00 -42.9 1.09 0.14 41 26.8 -0.80 15.1 -0.15 88.8 0.15 11.3 0.00 320.2 0.05 73.8 0.01 1.8 0.00 -6.0 -0.25 -40.6 -0.08 0.01 42 29.1 -0.64 16.8 5.00 95.9 0.05 11.6 -0.30 330.5 -0.08 74.7 0.00 1.8 0.00 -5.5 0.45 -42.5 0.91 0.01 32 30.2 -0.56 15.2 0.00 89.9 0.14 11.5 -0.16 324.4 0.00 74.2 0.00 1.9 0.00 -5.0 1.25 -42.9 1.09 0.00 30 30.1 -0.57 15.1 -0.15 89.8 0.14 11.4 -0.10 324.3 0.00 73.8 0.01 2.0 0.00 -5.7 0.10 -44.0 1.64 0.00 31a 28.2 -0.71 17.9 8.27 54.0 0.63 10.7 0.63 268.4 0.73 18.5 0.82 9.3 0.16 -5.4 0.66 -43.3 1.32 0.20 40 31.2 -0.49 15.2 0.00 97.9 0.03 12.4 -1.12 326.8 -0.03 75.2 -0.01 1.8 0.00 -5.3 0.77 -40.7 0.00 0.01 31 44.4 0.44 18.7 10.79 31.8 0.94 10.2 1.10 288.9 0.46 20.7 0.79 21.7 0.42 -5.9 -0.19 -42.9 1.09 0.46 44 44.1 0.42 18.6 10.45 31.9 0.94 10.1 1.21 289.5 0.46 18.9 0.81 20.9 0.40 -6.1 -0.57 -46.5 2.92 0.44 *) Sampling no 11 - 13 were displayed in Figure 3a) Sampling­ No Ca2+ Mg2+ Na+ K+ HCO3 - HCO3 - Cl- SO4 - δ18O δ2H Cl- SO4 - δ18O δ2H Sampling­ No*) Ca2+ Mg2+ Na+ K+ δ18ONO3 δ15NNO3 δ18ONO3 δ15NNO3 δ18ONO3 δ15NNO3 mg/l mp (0/00) (0/00) mg/l mp (0/00) (0/00) mg/l mp (0/00) (0/00) 10 1.31 0.29 4.1 20.7 16.5 c 23 3.2 0.79 4.3 6.4 12.9 c 11 2.00 0.14 3.0 18.5 13.4 c 1 1.59 3.8 38.0 28.7 d 22a 2.0 5.3 34.6 40.8 d 12 2.80 0.24 3.1 8.9 18.0 c 9 1.44 2.1 20.7 16.5 d 22 4.0 1.01 5.6 5.4 12.2 c 12a 2.99 3.1 2 1.05 0.22 5.2 21 2.1 5.3 3.6 8.2 b 12d 2.95 2.0 5a 3.00 0.74 2.5 15.6 18.4 c 33a 0.4 0.08 3.7 19.7 15.2 c 12f 2.99 2.3 33.7 38.3 b 3 1.06 2.1 25 0.5 5.5 3.8 5.7 b 17 2.58 0.21 2.0 20.1 17.8 c 5 1.89 0.45 4.3 15.4 18.0 c 20 2.0 0.50 4.0 5.2 11.4 c 13 3.80 0.36 2.9 8 3.97 2.1 38.0 28.7 d 24 0.5 3.2 4.7 8.7 b 29a 1.33 0.06 2.0 19.4 21.3 c 6c 1.20 2.3 24b 0.2 0.02 4.0 5.2 11.4 c 29 1.13 5.0 6 3.16 0.78 2.1 13.6 19.8 c 19c 0.3 0.06 2.2 18.6 14.6 c 30a 0.86 0.00 3.0 20.1 13.4 c 4 1.07 0.23 3.4 21.2 16.5 c 18a 0.2 0.01 4.4 19.8 16.2 c 43 6.59 0.70 3.9 19.4 21.7 c 4a 1.07 0.23 3.0 21.4 16.1 c 20a 0.6 0.13 3.2 6.8 10.4 c 28 6.59 3.5 6b 1.21 5.8 19 0.3 0.04 3.3 18.6 14.6 c 28a 5.70 0.59 2.8 14.2 20.2 c 6a 0.17 1.9 33 0.1 3.7 15.8 5.1 b 41 2.39 0.19 3.3 15.2 20.8 c 7c 5.34 2.7 -4.8 -2.7 a 27 0.3 0.04 7.0 18.6 12.5 c 42 2.39 4.0 -8.2 5.8 b 7 4.07 3.0 20.0 13.0 b 18 0.2 0.03 5.6 10.4 16.5 c 32 7.83 0.85 3.0 16.4 21.4 c 7b 3.63 2.7 11.9 16.5 a 19b 1.6 0.38 2.5 23.2 16.7 c 30 7.44 0.81 4.9 16.1 20.1 c 7a 3.63 6.3 20.7 18.0 a 31a 2.39 0.19 4.7 16.4 21.4 c 47 0.35 2.8 6.6 8.9 b 40 5.65 2.9 16.8 8.0 b 46 0.20 3.2 20.1 12.6 b 31 1.10 3.1 -8.4 7.2 b 45 1.71 0.40 2.8 21.2 19.1 c 44 1.05 3.0 -6.2 9.2 b 12 2.8 0.69 3.1 8.9 18.0 c *) Sampling no 11 - 13 were displayed in Figure 3a) 12d 3.0 2.0 12f 3.0 2.3 33.7 38.3 d 1 3.0 4.3 15 0.2 3.5 -1.5 6.0 b 15a 2.6 2.4 34 0.4 0.05 2.3 18.9 12.4 c 39b 2.5 3.2 8.5 25.8 a)­CMHI­area b)­RCK­area c)­DHYK­area Sampling­ No­(Dx) Nitrate composito nal­range Nitrate isotopes Sampling­ No­(Dx) Nitrate DO Nitrate isotopes NO3 - compositonal­ range NO3 - composito nal­range NO3 - DO Nitrate isotopes Sampling­ No­(Dx) Nitrate DO Appendix 3. Calculation results of mixing ratio of nitrate concentration and their nitrate isotopes. Appendix 2. Continuation.