Abstract
Arsenic (As) is widespread in alluvial aquifers along rivers draining the Himalayas but has received little attention along the Mekong River upstream of its delta. This study investigates linkages among groundwater recharge, flow, chemistry, and river stage at two sites along the Mekong River in northeast Thailand. Hydraulic head and chemistry were monitored in January and June 2014. In addition, hydraulic head and electrical conductivity were continuously logged at one site from January 2014 to March 2015. During the dry season, groundwater tends to flow toward the river, and saline water from shallow evaporites can intrude the alluvial aquifer. As stage rises, hydraulic-gradient reversals can result in groundwater-river water mixing, thereby promoting geochemical disequilibrium. Groundwater chemistry reflects silicate, carbonate, and evaporite weathering; multiple redox reactions; and spatial and temporal variability in recharge. Concentrations of As and manganese (Mn) in groundwater exceeded drinking-water guidelines by as much as an order of magnitude. Results suggest As is mobilized in groundwater by reduction of ferric (oxyhydr)oxides, consistent with the findings elsewhere in South and Southeast Asia. Upwelling of saline water can increase the solubility of (oxyhydr)oxide phases that sequester Mn and As, can complex Mn and can mobilize adsorbed As oxyanions. Conversely, influxes of oxic river water could promote (oxyhydr)oxide precipitation.
This is a preview of subscription content, access via your institution.
Availability of data and material
Datalogger measurements are available at https://doi.org/10.4211/52abfd80ae794c0588d133897dcfafa3 (CUAHSI Hydroshare). Other data generated as part of this study are available from the authors upon request.
References
Appelo CAJ, Postma D (2005) Geochemistry, groundwater and pollution, 2nd edn. CRC Press, Boca Raton
Appelo CAJ, Van Der Weiden MJJ, Tournassat C, Charlet L (2002) Surface complexation of ferrous iron and carbonate on ferrihydrite and the mobilization of arsenic. Environ Sci Technol 36:3096–3103. https://doi.org/10.1021/es010130n
Bein A, Dutton AR (1993) Origin, distribution, and movement of brine in the Permian Basin (U.S.A.): a model for displacement of connate brine. GSA Bull 105:695–707. https://doi.org/10.1130/0016-7606(1993)105%3c0695:ODAMOB%3e2.3.CO;2
Benner SG, Polizzotto ML, Kocar BD, Ganguly S, Phan K, Ouch K, Sampson M, Fendorf S (2008) Groundwater flow in an arsenic-contaminated aquifer, Mekong Delta, Cambodia. Appl Geochem 23:3072–3087. https://doi.org/10.1016/j.apgeochem.2008.06.013
Berg M, Trang PTK, Stengel C, Buschmann J, Viet PH, Dan NV, Giger W, Stüben D (2008) Hydrological and sedimentary controls leading to arsenic contamination of groundwater in the Hanoi area, Vietnam: The impact of iron-arsenic ratios, peat, river bank deposits, and excessive groundwater abstraction. Chem Geol 249:91–112. https://doi.org/10.1016/j.chemgeo.2007.12.007
Berube M, Jewell K, Myers K, Knappett P, Shuai P, Hossain A, Lipsi M, Hossain S, Hosain A, Aitkenhead-Peterson J, Ahmed K, Datta S (2018) The fate of arsenic in groundwater discharged to the Meghna River, Bangladesh. Environ Chem 15:29–45. https://doi.org/10.1071/en17104
Bhattacharya P, Chatterjee D, Jacks G (1997) Occurrence of arsenic-contaminated groundwater from the Bengal Delta Plain, Eastern India: options for a safe drinking water supply. Int J Water Resour Dev 13:79–92. https://doi.org/10.1080/07900629749944
Böttcher J, Strebel O, Voerkelius S, Schmidt HL (1990) Using isotope fractionation of nitrate-nitrogen and nitrate-oxygen for evaluation of microbial denitrification in a sandy aquifer. J Hydrol 113:413–424. https://doi.org/10.1016/0022-1694(90)90068-9
Brindha K, Pavelic P, Sotoukee T (2019) Environmental assessment of water and soil quality in the Vientiane Plain, Lao PDR. Groundw Sustain Dev 8:24–30. https://doi.org/10.1016/j.gsd.2018.08.005
Buschmann J, Berg M (2009) Impact of sulfate reduction on the scale of arsenic contamination in groundwater of the Mekong, Bengal and Red River deltas. Appl Geochem 24:1278–1286. https://doi.org/10.1016/j.apgeochem.2009.04.002
Buschmann J, Berg M, Stengel C, Sampson ML (2007) Arsenic and manganese contamination of drinking water resources in Cambodia: coincidence of risk areas with low relief topography. Environ Sci Technol 41:2146–2152. https://doi.org/10.1021/es062056k
Chanpiwat P, Lee B-T, Kim K-W, Sthiannopkao S (2014) Human health risk assessment for ingestion exposure to groundwater contaminated by naturally occurring mixtures of toxic heavy metals in the Lao PDR. Environ Monit Assess 186:4905–4923. https://doi.org/10.1007/s10661-014-3747-0
Climatological Group (2015) The climate of Thailand. Meteorological Development Bureau, Thai Meteorological Department. https://www.tmd.go.th/en/archive/thailand_climate.pdf. Accessed 16 July 2020
ClimaTemps (2017) World climate and temperature. http://www.climatemps.com/. Accessed 27 Dec 2017
Craig H (1961) Isotopic variations in meteoric water. Science 133:1702–1703. https://doi.org/10.1126/science.133.3465.1702
Datta S, Neal AW, Mohajerin TJ, Ocheltree T, Rosenheim BE, White CD, Johannesson KH (2011) Perennial ponds are not an important source of water or dissolved organic matter to groundwaters with high arsenic concentrations in West Bengal. India Geophys Res Lett 38:L20404. https://doi.org/10.1029/2011GL049301
Diem D, Stumm W (1984) Is dissolved Mn2+ being oxidized by O2 in absence of Mn-bacteria or surface catalysts? Geochim Cosmochim Acta 48:1571–1573. https://doi.org/10.1016/0016-7037(84)90413-7
El Tabakh M, Utha-Aroon C, Schreiber BC (1999) Sedimentology of the Cretaceous Maha Sarakham evaporites in the Khorat Plateau of northeastern Thailand. Sed Geol 123:31–62. https://doi.org/10.1016/S0037-0738(98)00083-9
Erban LE, Gorelick SM, Zebker HA, Fendorf S (2013) Release of arsenic to deep groundwater in the Mekong Delta, Vietnam, linked to pumping-induced land subsidence. Proc Nat Acad Sci USA 110:13751–13756. https://doi.org/10.1073/pnas.1300503110
Fendorf S, Michael HA, van Geen A (2010) Spatial and temporal variations of groundwater arsenic in South and Southeast Asia. Science 328:1123–1127. https://doi.org/10.1126/science.1172974
Gaillardet J, Dupré B, Louvat P, Allègre CJ (1999) Global silicate weathering and CO2 consumption rates deduced from the chemistry of large rivers. Chem Geol 159:3–30. https://doi.org/10.1016/S0009-2541(99)00031-5
Geological Survey Division (1985a) Changwat Nakhon Phanom and Pakxan. 1:250,000 scale geologic map, 1 sheet. Department of Mineral Resources, Thailand
Geological Survey Division (1985b) Changwat Roi Et. 1:250,000 scale geologic map, 1 sheet. Department of Mineral Resources, Thailand
Geological Survey Division (1985c) Changwat Udon Thani and Vang Vieng. 1:250,000 scale geologic map, 1 sheet. Department of Mineral Resources, Thailand
Hafeman D, Factor-Litvak P, Cheng Z, van Geen A, Ahsan H (2007) Association between manganese exposure through drinking water and infant mortality in Bangladesh. Environ Health Perspect 115:1107–1112. https://doi.org/10.1289/ehp.10051
Haile E, Fryar AE (2017) Chemical evolution of groundwater in the Wilcox aquifer of the northern Gulf Coastal Plain, USA. Hydrogeol J 25:2403–2418. https://doi.org/10.1007/s10040-017-1608-y
Harvey CF, Swartz CH, Badruzzaman ABM, Keon-Blute N, Yu W, Ali MA, Jay J, Beckie R, Niedan V, Brabander D, Oates PM, Ashfaque KN, Islam S, Hemond HF, Ahmed MF (2002) Arsenic mobility and groundwater extraction in Bangladesh. Science 298:1602–1606. https://doi.org/10.1126/science.1076978
Harvey CF, Ashfaque KN, Yu W, Badruzzaman ABM, Ali MA, Oates PM, Michael HA, Neumann RB, Beckie R, Islam S, Ahmed MF (2006) Groundwater dynamics and arsenic contamination in Bangladesh. Chem Geol 228:112–136. https://doi.org/10.1016/j.chemgeo.2005.11.025
Hecht JS, Lacombe G, Arias ME, Dang TD, Piman T (2019) Hydropower dams of the Mekong River basin: a review of their hydrological impacts. J Hydrol 568:285–300. https://doi.org/10.1016/j.jhydrol.2018.10.045
Hem JD (1981) Rates of manganese oxidation in aqueous systems. Geochim Cosmochim Acta 45:1369–1374. https://doi.org/10.1016/0016-7037(81)90229-5
IAEA/WMO (2020) Global network of isotopes in precipitation. The GNIP database. International Atomic Energy Agency, Vienna. https://nucleus.iaea.org/wiser/index.aspx. Accessed 25 May 2020
Islam FS, Gault AG, Boothman C, Polya DA, Charnock JM, Chatterjee D, Lloyd JR (2004) Role of metal-reducing bacteria in arsenic release from Bengal basin sediments. Nature 430:68–71. https://doi.org/10.1038/nature02638
Kharaka YK, Gunter WD, Aggarwal PK, Perkins EH, DeBraal JD (1988) SOLMINEQ.88; a computer program for geochemical modeling of water-rock interactions. US Geol Surv Water-Resour Inv Rep. https://doi.org/10.3133/wri884227
Kinniburgh DG, Smedley PL (eds) (2001) Arsenic contamination of groundwater in Bangladesh, vol. 2: final report. British Geological Survey (BGS) Tech Rep WC/00/19, Keyworth
Kocar BD, Polizzotto ML, Benner SG, Ying SC, Ung M, Ouch K, Samreth S, Suy B, Phan K, Sampson M, Fendorf S (2008) Integrated biogeochemical and hydrologic processes driving arsenic release from shallow sediments to groundwaters of the Mekong delta. Appl Geochem 23:3059–3071. https://doi.org/10.1016/j.apgeochem.2008.06.026
Lacombe G, Douangsavanh S, Vongphachanh S, Pavelic P (2017) Regional assessment of groundwater recharge in the Lower Mekong Basin. Hydrology 4:60. https://doi.org/10.3390/hydrology4040060
LaMoreaux PE, Charaljavanaphet J, Jalichan N, Chiengmai PPN, Bunnag D, Thavisri A, Rakprathum C (1958) Reconnaissance of the geology and groundwater of the Khorat Plateau, Thailand. US Geol Surv Water-Supply Pap. https://doi.org/10.3133/wsp1429
Lawson M, Polya DA, Boyce AJ, Bryant C, Mondal D, Shantz A, Ballentine CJ (2013) Pond-derived organic carbon driving changes in arsenic hazard found in Asian groundwaters. Environ Sci Technol 47:7085–7094. https://doi.org/10.1021/es400114q
Lawson M, Polya DA, Boyce AJ, Bryant C, Ballentine CJ (2016) Tracing organic matter composition and distribution and its role on arsenic release in shallow Cambodian groundwaters. Geochimica Cosmochim Acta 178:160–177. https://doi.org/10.1016/j.gca.2016.01.010
Li D, Long D, Zhao J, Lu H, Hong Y (2017) Observed changes in flow regimes in the Mekong River basin. J Hydrol 551:217–232. https://doi.org/10.1016/j.jhydrol.2017.05.061
Lovley DR (1987) Organic matter mineralization with the reduction of ferric iron: a review. Geomicrobiol J 5:375–399. https://doi.org/10.1080/01490458709385975
Lowers HA, Breit GN, Foster AL, Whitney J, Yount J, Uddin MN, Muneem AA (2007) Arsenic incorporation into authigenic pyrite, Bengal Basin sediment, Bangladesh. Geochim Cosmochim Acta 71:2699–2717. https://doi.org/10.1016/j.gca.2007.03.022
McArthur JM, Banerjee DM, Sengupta S, Ravenscroft P, Klump S, Sarkar A, Disch B, Kipfer R (2010) Migration of As, and 3H/3He ages, in groundwater from West Bengal: implications for monitoring. Water Res 44:4171–4185. https://doi.org/10.1016/j.watres.2010.05.010
McArthur JM, Nath B, Banerjee DM, Purohit R, Grassineau N (2011) Palaeosol control on groundwater flow and pollutant distribution: the example of arsenic. Environ Sci Technol 45:1376–1383. https://doi.org/10.1021/es1032376
McArthur JM, Sikdar PK, Hoque MA, Ghosal U (2012) Waste-water impacts on groundwater: Cl/Br ratios and implications for arsenic pollution of groundwater in the Bengal Basin and Red River Basin. Vietnam Sci Total Environ 437:390–402. https://doi.org/10.1016/j.scitotenv.2012.07.068
McArthur JM, Sikdar PK, Nath B, Grassineau N, Marshall JD, Banerjee DM (2012) Sedimentological control on Mn, and other trace elements, in groundwater of the Bengal Delta. Environ Sci Technol 46:669–676. https://doi.org/10.1021/es202673n
Mehta S, Fryar AE, Banner JL (2000) Controls on the regional-scale salinization of the Ogallala aquifer, Southern High Plains, Texas, USA. Appl Geochem 15:849–864. https://doi.org/10.1016/S0883-2927(99)00098-0
Mozumder MRH, Michael HA, Mihajlov I, Khan MR, Knappett PSK, Bostick BC, Mailloux BJ, Ahmed KM, Choudhury I, Koffman T, Ellis T, Whaley-Martin K, San Pedro R, Slater G, Stute M, Schlosser P, van Geen A (2020) Origin of groundwater arsenic in a rural Pleistocene aquifer in Bangladesh depressurized by distal municipal pumping. Water Resour Res 55:e2020WR027178. https://doi.org/10.1029/2020WR027178
MRC (2010) State of the basin report 2010. Mekong River Commission, Vientiane, Lao PDR. http://www.mrcmekong.org/assets/Publications/basin-reports/MRC-SOB-report-2010full-report.pdf. Accessed 25 May 2020
MRC (2011) Planning atlas of the Lower Mekong Basin. Mekong River Commission, Vientiane, Lao PDR. http://www.mrcmekong.org/assets/Publications/basin-reports/BDP-Atlas-Final-2011.pdf. Accessed 16 July 2020
MRC (2020) Annual report 2019, part 1: progress and achievements. Mekong River Commission, Vientiane, Lao PDR. http://www.mrcmekong.org/assets/Publications/AR2019-Part-1.pdf. Accessed 16 July 2020
Mukherjee A, Fryar AE (2008) Deeper groundwater chemistry and geochemical modeling of the arsenic affected western Bengal basin, West Bengal, India. Appl Geochem 23:863–894. https://doi.org/10.1016/j.apgeochem.2007.07.011
Mukherjee A, Fryar AE, Scanlon BR, Bhattacharya P, Bhattacharya A (2011) Elevated arsenic in deeper groundwater of the western Bengal basin, India: extent and controls from regional to local scale. Appl Geochem 26:600–613. https://doi.org/10.1016/j.apgeochem.2011.01.01
Mukherjee A, Verma S, Gupta S, Henke KR, Bhattacharya P (2014) Influence of tectonics, sedimentation, and aqueous flow cycles on the origin of global groundwater arsenic: paradigms from three continents. J Hydrol 518:284–299. https://doi.org/10.1016/j.jhydrol.2013.10.044
Munger ZW, Carey CC, Gerling AB, Hamre KD, Doubek JP, Klepatzki SD, McClure RP, Schreiber ME (2016) Effectiveness of hypolimnetic oxygenation for preventing accumulation of Fe and Mn in a drinking water reservoir. Water Res 106:1–14. https://doi.org/10.1016/j.watres.2016.09.038
Neumann RB, Ashfaque KN, Badruzzaman ABM, Ali MA, Shoemaker JK, Harvey CF (2010) Anthropogenic influences on groundwater arsenic concentrations in Bangladesh. Nat Geosci 3:46–52. https://doi.org/10.1038/ngeo685
Nickson RT, McArthur JM, Ravenscroft P, Burgess WG, Ahmed KM (2000) Mechanism of arsenic release to groundwater, Bangladesh and West Bengal. Appl Geochem 15:403–413. https://doi.org/10.1016/S0883-2927(99)00086-4
Parkhurst DL, Appelo CAJ (2013) Description of input and examples for PHREEQC version 3: a computer program for speciation, batch-reaction, one-dimensional transport, and inverse geochemical calculations. US Geol Surv Techn Methods. https://doi.org/10.3133/tm6A43
Podgorski J, Berg M (2020) Global threat of arsenic in groundwater. Science 368:845–850. https://doi.org/10.1126/science.aba1510
Polizzotto ML, Harvey CF, Sutton SR, Fendorf S (2005) Processes conducive to the release and transport of arsenic into aquifers in Bangladesh. Proc Nat Acad Sci USA 102:18819–18823. https://doi.org/10.1073/pnas.0509539103
Polizzotto ML, Kocar BD, Benner SG, Sampson M, Fendorf S (2008) Near-surface wetland sediment as a source of arsenic release to ground water in Asia. Nature 454:505–509. https://doi.org/10.1038/nature07093
Promma K, Zheng C, Asnachinda P (2006) Groundwater and surface-water interactions in a confined alluvial aquifer between two rivers: effects of groundwater flow dynamics on high iron anomaly. Hydrogeol J 15:495–513. https://doi.org/10.1007/s10040-006-0110-8
Rahman MM, Naidu R, Bhattacharya P (2009) Arsenic contamination in groundwater in the Southeast Asia region. Environ Geochem Health 31:9–21. https://doi.org/10.1007/s10653-008-9233-2
Räsänen TA, Someth P, Lauri H, Kopenen J, Sarkkula J, Kummu M (2017) Observed river discharge changes due to hydropower operations in the Upper Mekong Basin. J Hydrol 545:28–41. https://doi.org/10.1016/j.jhydrol.2016.12.023
Ravenscroft P, Brammer H, Richards KS (2009) Arsenic pollution: a global synthesis. Wiley-Blackwell, Malden
Richards LA, Magnone D, Sovann C, Kong C, Uhlemann S, Kuras O, van Dongen BE, Ballentine CJ, Polya DA (2017) High resolution profile of inorganic aqueous geochemistry and key redox zones in an arsenic bearing aquifer in Cambodia. Sci Tot Environ 590–591:540–553. https://doi.org/10.1016/j.scitotenv.2017.02.217
Richards LA, Sültenfuß J, Chambers L, Bryant C, Boyce AJ, van Dongen BE, Ballentine CJ, Sovann C, Uhlemann S, Kuras O, Gooddy DC, Polya DA (2019) Dual in-aquifer and near surface processes drive arsenic mobilization in Cambodian groundwaters. Sci Tot Environ 659:699–714. https://doi.org/10.1016/j.scitotenv.2018.12.437
Scanlon BR, Nicot JP, Reedy RC, Kurtzman D, Mukherjee A, Nordstrom DK (2009) Elevated naturally occurring arsenic in a semiarid oxidizing system, Southern High Plains aquifer, Texas, USA. Appl Geochem 24:2061–2071. https://doi.org/10.1016/j.apgeochem.2009.08.004
Shin S, Pokhrel Y, Yamazaki D, Huang X, Torbick N, Qi J, Pattanakiat S, Ngo-Duc T, Nguyen TD (2020) High resolution modeling of river-floodplain-reservoir inundation dynamics in the Mekong River Basin. Water Resour Res 56:e2019WR26449. https://doi.org/10.1029/2019WR026449
Srisuk K, Sribooniue V, Buaphan C, Archvichai L, Youngme W, Satarak P, Jaruchaikul S (2001) Numerical modeling of saline water transport in the lower Nam Kam basin, Amphoe That Phanom, Changwat Nakhon Phanom, Thailand. Water Sci Technol 44(7):159–164. https://doi.org/10.2166/wst.2001.0414
Stahl MO, Harvey CF, van Geen A, Sun J, Thi Kim Trang P, Mai Lan V, Mai Phuong T, Hung Viet P, Bostick BC (2016) River bank geomorphology controls groundwater arsenic concentrations in aquifers adjacent to the Red River, Hanoi Vietnam. Water Resour Res 52:6321–6334. https://doi.org/10.1002/2016WR018891
Stanger G (2005) A palaeo-hydrological model for arsenic contamination in southern and south-east Asia. Environ Geochem Health 27:359–367. https://doi.org/10.1007/s10653-005-7102-9
Steefel CI, Van Cappellen P (1990) A new kinetic approach to modeling water-rock interaction: the role of nucleation, precursors, and Ostwald ripening. Geochim Cosmochim Acta 54:2657–2677. https://doi.org/10.1016/0016-7037(90)90003-4
Tardy Y (1971) Characterization of the principal weathering types by the geochemistry of waters from some European and African crystalline massifs. Chem Geol 7:253–271. https://doi.org/10.1016/0009-2541(71)90011-8
US Geological Survey (2018) Alkalinity calculator. http://or.water.usgs.gov/alk/. Accessed 25 May 2020
US Geological Survey (2020) PHREEQC version 3. https://www.usgs.gov/software/phreeqc-version-3. Accessed 10 July 2020
van Geen A, Zheng Y, Goodbred S Jr, Horneman A, Aziz Z, Cheng Z, Stute M, Mailloux B, Weinman B, Hoque MA, Seddique AA, Hossain MS, Chowdhury SH, Ahmed KM (2008) Flushing history as a hydrogeological control on the regional distribution of arsenic in shallow groundwater of the Bengal Basin. Environ Sci Technol 42:2283–2288. https://doi.org/10.1021/es702316k
van Geen A, Bostick BC, Trang PTK, Lan VN, Mai N-N, Manh PD, Viet PH, Radloff K, Aziz Z, Mey JL, Stahl MO, Harvey CF, Oates P, Weinman B, Stengel C, Frei F, Kipfer R, Berg M (2013) Retardation of arsenic transport through a Pleistocene aquifer. Nature 501:204–207. https://doi.org/10.1038/nature12444
Vega MA, Kulkarni HV, Mladenov M, Johannesson K, Hettiarachchi GM, Bhattacharya P, Kumar N, Weeks J, Galkaduwa M, Datta S (2017) Biogeochemical controls on the release and accumulation of Mn and As in shallow aquifers, West Bengal. India Front Environ Sci 5:29. https://doi.org/10.3389/fenvs.2017.00029
von Brömssen M, Jakariya M, Bhattacharya P, Ahmed KM, Hasan MA, Sracek O, Jonsson L, Lundell L, Jacks G (2007) Targeting low-arsenic aquifers in Matlab Upazila, Southeastern Bangladesh. Sci Total Environ 379:121–132. https://doi.org/10.1016/j.scitotenv.2006.06.028
Wallis I, Prommer H, Berg M, Siade AJ, Sun J, Kipfer R (2020) The river–groundwater interface as a hotspot for arsenic release. Nat Geosci 13:288–295. https://doi.org/10.1038/s41561-020-0557-6
Wannakomol A (2005) Soil and groundwater salinization problems in the Khorat Plateau, NE Thailand. Doctoral dissertation, Freie Universität Berlin, Germany
Weinman B, Goodbred SL Jr, Zheng Y, Aziz Z, Steckler M, van Geen A, Singhvi AK, Nagar YC (2008) Contributions of floodplain stratigraphy and evolution to the spatial patterns of groundwater arsenic in Araihazar, Bangladesh. GSA Bull 120:1567–1580. https://doi.org/10.1130/B26209.1
Winkel L, Berg M, Amini M, Hug SJ, Johnson CA (2008) Predicting groundwater arsenic contamination in Southeast Asia from surface parameters. Nat Geosci 1:536–542. https://doi.org/10.1038/ngeo254
WLE Greater Mekong (2016) Dams in the Mekong River Basin: commissioned, under construction and planned dams in April 2016. 1:2,500,000 scale map, 1 sheet. CGIAR Research Program on Water, Land and Ecosystems–Greater Mekong, Vientiane, Lao PDR.
Wood WW (1976) Guidelines for collection and field analysis of ground-water samples for selected unstable constituents. US Geol Surv Tech Water-Resour Inv. https://doi.org/10.3133/twri01D2
Yang K, Han G (2020) Controls over hydrogen and oxygen isotopes of surface water and groundwater in the Mun River catchment, northeast Thailand: implications for the water cycle. Hydrogeol J 28:1021–1036. https://doi.org/10.1007/s10040-019-02106-9
Yang K, Han G, Zeng J, Liang B, Qu R, Liu J, Liu M (2019) Spatial variation and controlling factors of H and O isotopes in Lancang River water, southwest China. Int J Environ Res Public Health 16:4932. https://doi.org/10.3390/ijerph16244932
Zhao Z, Li S, Xue L, Liao J, Zhao J, Wu M, Wang M, Sun J, Zheng Y, Yang Q (2020) Effects of dam construction on arsenic mobility and transport in two large rivers in Tibet, China. Sci Total Environ 741:140406. https://doi.org/10.1016/j.scitotenv.2020.140406
Acknowledgements
The authors acknowledge the National Research Council of Thailand for permission to conduct this project (# 2774); staff of the Groundwater Resources Institute at Khon Kaen University for logistical support; land owners at the study sites for access; the Mekong River Commission and Thai Meteorological Department for data; Joshua Benton for drafting Fig. 1; and the journal reviewers for their constructive suggestions, which improved the manuscript.
Funding
The authors acknowledge the U.S. National Science Foundation (grants IIA-1338204 and IIA-1338213) and Khon Kaen University for funding.
Author information
Authors and Affiliations
Corresponding author
Ethics declarations
Conflict of interest
The authors report no potential conflict of interest.
Additional information
Publisher's Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Supplementary Information
Below is the link to the electronic supplementary material.
12665_2021_9522_MOESM1_ESM.docx
Supplementary file1 Fig. S1. Mekong River stage at Vientiane (VI) and daily rainfall at Sri Chiang Mai (SCM) and Tha Bo (TB) for calendar year 2014. Rainfall data were not available for November–December 2014 at SCM. Stars denote sampling periods (DOCX 59 KB)
12665_2021_9522_MOESM2_ESM.docx
Supplementary file2 Fig. S2. Mekong River stage and daily rainfall at Nakhon Phanom (NP) and Mukdahan (MUK) for January 2014–March 2015 (DOCX 64 KB)
12665_2021_9522_MOESM3_ESM.docx
Supplementary file3 Fig. S3. Plot of SC vs. pH; rectangular outlines denote transects at Sri Chiang Mai site (SCM) and well nests at That Phanom (TP). Dashed circles represent spatial outliers (PN3/21 and PN4/21) (DOCX 48 KB)
12665_2021_9522_MOESM4_ESM.tif
Supplementary file4 Fig. S4. Piper plot showing major-ion compositions. Red and blue denote water samples collected in January and June 2014, respectively. Symbols: triangle = Sri Chiang Mai site groundwater; clover = That Phanom groundwater; square = Sri Chiang Mai river water; circle = That Phanom river water (TIF 3940 KB)
12665_2021_9522_MOESM5_ESM.docx
Supplementary file5 Fig. S5. Mean and median monthly values (1968–2015) of δ18O and δ2H for Bangkok GNIP samples (IAEA/WMO 2020) (DOCX 63 KB)
12665_2021_9522_MOESM6_ESM.pdf
Supplementary file6 Table S1. Location, completion information, and hydraulic head for wells monitored in this study. Table S2. Calculated saturation indices for phases that may control groundwater chemistry and charge balance error. Table S3. Proportions of upgradient groundwater (from TW-2 or OW-17) and Mekong River water in wells OW-22 and OW-37 at Sri Chiang Mai based on isotope end-member mixing calculations (PDF 298 KB)
Rights and permissions
About this article
Cite this article
Fryar, A.E., Schreiber, M.E., Pholkern, K. et al. Variability in groundwater flow and chemistry in the Mekong River alluvial aquifer (Thailand): implications for arsenic and manganese occurrence. Environ Earth Sci 80, 225 (2021). https://doi.org/10.1007/s12665-021-09522-9
Received:
Accepted:
Published:
DOI: https://doi.org/10.1007/s12665-021-09522-9
Keywords
- Arsenic
- Groundwater
- Mekong River
- Salinization
- Thailand