In this study, the sources causing high concentrations of NO3- and NH4+ in
groundwater, the transformation within N-budget system of the sources, the contribution
of nitrogen compounds to the release of As into groundwater, and the simulations of N
transformation and transport in As-rich groundwater of Choushui river alluvial fan have
been identified.
First, the results obtained for δ15NNO3 and δ18ONO3 suggest that NO3− denitrification
by microorganisms may occur from the upstream region to the downstream region of the
Choushui River. The NO3− concentrations decrease in the downstream direction.
The sources of NO3− in the proximal fan of the Choushui River alluvial fan may be
ammonium fertilizers, soil ammonium, and manure and septic waste. Because the
groundwater tends to be oxidative, NH4+ is converted to NO3− (nitrification) once the
NH4+ sources infiltrate the groundwater, resulting in the enrichment of NO3−. However,
there is no clear evidence for NO3− assimilation by living organisms or NO3−
denitrification by microorganisms in the proximal fan.
The physicochemical characteristics and the relatively low value of δ18ONO3 in the
proximal fan of the Choushui River alluvial fan indicates the possibility of oxygen from
sources other than NO3−
entering the groundwater. Atmospheric oxygen serves as an
alternative to the oxygen in NO3− for microbial activities. The entry of atmospheric
oxygen results from unconfined granular nature and overpumping of groundwater for
agricultural activities.
The lnNO3− versus δ15NNO3 plot for the mid-fan of the Choushui River alluvial fan
suggests that NO3− assimilation and denitrification may occur in the groundwater.
However, the ratio δ15N/δ18O shows only mild denitrification, suggesting that NO3−
assimilation by living organisms, rather than denitrification, is dominant and responsible
for the depletion of NO3−
. The environment of high concentrations of As, NH4+ and Fe,
and the depletion of δ15NNO3 suggest the occurrence of feammox process in the mid-fan,
causing As to desorb from Fe oxyhydroxides and release to groundwater.
The NO3− sources in the mid-fan and the distal fan of the Choushui River alluvial fan
appear to be nitrate fertilizers and marine nitrate. NO3− is assimilated and mineralized to
NH4+ by heterorganic microbes or through DNRA in the reductive groundwater, leading
to the enrichment of NH4+ in the groundwater. The lnNO3− versus δ15NNO3 plot shows the
possibility of NO3− assimilation and denitrification in the groundwater. The ratio
δ15N/δ18O in the distal fan indicates that NO3− denitrification is significant, and the
enrichment of both 15NNO3 and 18ONO3 support this indication. In other words, assimilation,
mineralization, DNRA, and denitrification should occur simultaneously in the distal fan
of the Choushui River alluvial fan, resulting in the depletion of NO3− and enrichment of
NH4+ in the groundwater.
High NO3− concentrations in the groundwater of the proximal fan result in an
oxidative environment, which is not favorable for the reductive dissolution of
As-containing Fe oxyhydroxides. By contrast, feammox in the mid-fan and denitrification in
the distal fan may lead to the reductive dissolution of As-containing Fe oxyhydroxides,
resulting in the release of As into the groundwater; because of the reductive environment,
NH4+ and As are present in considerable amounts.
Furthermore, the PHREEQC simulation suggested that 92.31% of NH4+ in the
proximal fan, 69.70% of NH4+ in the mid-fan, and 21.17% of NH4+ in the distal fan
simulatively oxidized to NO3− through nitrification and/or feammox. These data clearly
show that the nitrification and/or Feammox mostly occur in the proximal fan and
mid-fan, whereas they slightly occur in the distal fan. The reaction of nitrification leads to the
consequence of groundwater being abundant in NO3− and being depleted in NH4+. The
mean concentrations of NO3− and NH4+ in the proximal fan are 23.62 mg/L and 0.17 mg/L,
respectively, evidently supporting the occurrence of NH4+ nitrification. Also, the
proximal fan was assessed on the basis of local DO and ORP values to be in an oxidative
state, initiatively urging the occurrence of nitrification.
32.93% of NO3−
in the mid-fan and 61.13% of NO3−
in the distal fan simulatively
reduced to N2 or NH4+ through denitrification and/or DNRA. The spatial concentration
distribution of NO3− from the proximal fan to the distal fan indicates the gradual
occurrence of NO3− denitrification and/or DNRA from upstream to downstream of the
Choushui River alluvial fan. Also, the mid-fan and the distal fan were assessed on the
basis of the local DO and ORP values to be in relatively more reductive conditions,
driving the occurrence of denitrification and/or DNRA. Moreover, the concentration of
NH4+ in the distal fan indicates that in addition to denitrification, DNRA might be the
dominant process of N cycling in the distal fan.
In the proximal fan, As3+ decreased by 1.32E−4 mg/L, and this valence
transformation of As species and As concentration difference seem comprehensible. In
the mid-fan and the distal fan, the reductive state was observed base on the DO and ORP
data of the groundwater, and the circumstance of reduction from As5+ to As3+ was
obvious, reaching 6.62E−3 mg/L and 6.40E−3 mg/L, respectively.
The discrepancy of δ15N in NO3−
in groundwater was simulated on the basis of the
influence of the reaction of NO3− denitrification. The values of δ15NNO3 in the
groundwater of the mid-fan and the distal fan increased by +2.11% and +5.79%,
respectively. The δ15N value of the residual NO3−
increases with a decrease in the NO3−
concentration during denitrification. Further, the reductive environment further enhances
the reductive dissolution of As-bearing Fe oxyhydroxides and the desorption of adsorbed
As, resulting in the release of As into groundwater.
The 1-D transport simulation result suggested that NO3− assimilation occur from the
mid-fan of the Choushui River Alluvial Fan to the distal fan, whereas NH4+ nitrification
is observed at the beginning of the proximal fan. The initial and twenty-five years of NO3−
and NH4+ transport have little shift backward but are insignificant.
The total amount of As increased along the upstream to the downstream of the
Choushui River. The concentration of As5+increased at the beginning of the mid-fan,
which may be caused by the reductive dissolution of As-bearing Fe oxyhydroxides and
the desorption of adsorbed As. The concentration of As3+ increased obviously at the
beginning of the distal fan, which may be related to the transformation of As5+to As3+ in
the reductive environment, and the continuous desorption of As from Fe oxyhydroxides
simultaneously.
Both the concentrations of Fe3+ and Fe2+ increased at the end of proximal, causing
by the reductive dissolution of Fe oxyhydroxides. The transformation of Fe3+ to Fe2+
occurred soon when the groundwater reached the mid-fan, resulting in depletion of Fe3+
and increase in Fe2+ in groundwater. The increase in Fe2+ is not only related to the
reductive environment, but also attributed to the reaction of feammox, which Fe
oxyhydroxides react with NH4+ and produce Fe2+ in the groundwater.
References
Agricultural Engineering Research Center. Analysis and evaluation of the groundwater quality
survey in Taiwan, 2010; 2012. Taiwan Water Resource Bureau. Taipei.
Akai, J., Izumi, K., Fukuhara, H., Masuda, H., Nakano, S., Yoshimura, T., Ohfuji, H.,
Anawar, H.M., Akai, K., 2004. Mineralogical and geomicrobiological
investigations on groundwater arsenic enrichment in Bangladesh. Applied
Geochemistry. 19(2), 215-230.
Amberger, A., Schmidt, H.L., 1987. Natürliche isotopengehalte von nitrat als
indikatoren für dessen Herkunft. Geochimica et Cosmochimica Acta. 51(10),
2699-2705.
Anawar, H.M., Tareq, S.M., Ahmed, G., 2013. Is organic matter a source or redox driver
or both for arsenic release in groundwater? Physics and Chemistry of the Earth.
58-60, 49-56.
Andersson, K.K., Hooper, A.B., 1983. O2 and H2O are each the source of one O in NO2
-produced from NH3 by Nitrosomonus: 15N-NMR evidence. FEBS Letters. 164(2),
236-240.
Andersson P, Torssander P, Ingri J. Sulphur isotope ratios in sulphate and oxygen isotopes in
water from a small watershed in central Sweden. Hydrobiologia 1992;235/236:205–17.
Aravena, R., Robertson, W.D., 1998. Use of multiple isotope tracers to evaluate
denitrification in ground water: Study of nitrate from a large-flux septic system
plume. Ground Water. 36(6), 975-982.
Brenot , A., Carignan, J., France-Lanord, C., Benoìt, M., 2007. Geological and land use control
on d34S and d18O of river dissolved sulfate: the Moselle river basin, France. Chem. Geol.
244, 25-41.
Central Geological Survey. Project of groundwater monitoring network in Taiwan during first
stage-research report of Chou-Shui River alluvial fan, Taiwan. Taiwan Water Resource
Bureau Taipei. 1999. (In Chinese)
Cifuentes, L.A., Fogel, M.L., Pennock, J.R., Sharp, J.H., 1989. Biogeochemical factors
that influence the stable nitrogen isotope ratio of dissolved ammonium in the
Delaware Estuary. Geochimica et Cosmochimica Acta. 53(10), 2713-2721.
Clark I, Fritz P. Groundwater quality. In: Stein J, Starkweather AW, editors. Environmental
isotopes in hydrogeology. Boca Raton (NY): Lewis; 1997. p. 142–3.
Cook, P.G.E., Herczeg, A.L.E., 2000. Environmental Tracers in Subsurface Hydrology.
Kendall C, Aravena R, editors: Springer Science+Business Media, LLC, New York.
261-297 p.
Deutsch, B., Mewes, M., Liskow, I., Voss, M., 2006. Quantification of diffuse nitrate
inputs into a small river system using stable isotopes of oxygen and nitrogen in
nitrate. Organic Geochemistry. 37(10), 1333-1342.
Farooq, S.H., Chandrasekharam, D., Berner, Z., Norra, S., Stüben, D., 2010. Influence
of traditional agricultural practices on mobilization of arsenic from sediments to
groundwater in Bengal delta. Water Research. 44, 5575-5588.
Fukada, T., Hiscock, K.M., Dennis, P.F., 2004. A dual-isotope approach to the nitrogen
hydrochemistry of an urban aquifer. Applied Geochemistry. 19(5), 709-719.
Fukada, T., Hiscock, K.M., Dennis, P.F., Grischek, T., 2003. A dual isotope approach to
identify denitrification in groundwater at a river-bank infiltration site. Water
Research. 37(13), 3070-3078.
Hartland A, Larsen JR, Andersen MS, Baalousha M, O’Carroll D. Association of
Arsenic and Phosphorus with Iron Nanoparticles between Streams and Aquifers:
Implications for Arsenic Mobility. Environmental Science & Technology.
2015;49:14101-9.
Harvey, C.F., Swartz, C.H., Badruzzaman, A.B., Keon-Blute, N., Yu, W., Ali, M.A., Jay,
J., Beckie, R., Niedan, V., Brabander, D., Oates, P.M., Ashfaque, K.N., Islam, S.,
Hemond, H.F., Ahmed, M.F., 2002. Arsenic mobility and groundwater extraction
in Bangladesh. Science. 298(5598), 1602-1606.
Hollocher, H.C., 1984. Source of the oxygen atoms of nitrate in the oxidation of nitrite
by nitrobacter agilis and evidence against a P-O-N anhydride mechanism in
oxidative phosphorylation. Archives of Biochemistry and Biophysics. 233(2),
721-727.
Hosono, T., Wang, C.H., Umezawa, Y., Nakano, T., Onodera, S., Nagata, T., Yoshimizu, C.,
Tayasu, I., Taniguchi, M., 2011. Multiple isotope (H, O, N, S and Sr) approach elucidates
complex pollution causes in the shallow groundwaters of the Taipei urban area. J. Hydrol.
397, 23-36.
Hsu, C.H., Han, S.T., Kao, Y.H., Liu, C.W., 2010. Redox characteristics and zonation of
arsenic-affected multi-layers aquifers in the Choushui River alluvial fan, Taiwan.
Journal of Hydrology. 391(3-4), 351-66.
IAEA (International Atomic Energy Agency), 1983. Guidebook on Nuclear Techniques in
Hydrology. Tech. Rep. Ser. 91, 439.
Ingraham, N.L. (1998). Isotopic variation in precipitation. Chpater3, In: Kendall C. and
McDonnell J.J. (eds), Isotope Tracers in Catchment Hydrology, Elsevier, Amsterdam,
87-118
Kao, Y.H., Liu, C.W., Wang, S.W., Lee, C.H., 2012. Estimating mountain block recharge
to downstream alluvial aquifers from standard methods. Journal of Hydrology.
426-427, 93-102.
Kao, Y. H., Liu, C. W., Wang, S. W., Wang, P.L., Wang, C.H., Maji, S.K., 2011. Biogeochemical
cycling of arsenic in coastal salinized aquifers: evidence from sulfur isotope study. Sci.
Total Environ. 409, 4818-4830.
Karr, J.D., Showers, W.J., Gilliam, J.W., Andres, A.S., 2001. Tracing nitrate transport
and environmental impact from intensive swine farming using delta nitrogen-15.
Journal of Environmental Quality. 30(4), 1163-1175.
Kendall, C., 1998. Tracing nitrogen source and cycling in catchments. In: Kendall, C.,
McDonnell, J.J. (Eds.), Isotope Tracers in Catchment Hydrology. Elsevier Science B.V,
The Netherlands, 519-576.
Kendall, C.E., McDonnell, J.J.E., 1998. Isotope Tracers in Catchment Hydrology.
Caldwell EA, editors: Elsevier Science B.V., Amsterdam. 51-86 p.
Kinniburgh DG and Cooper DM. Predominance and mineral stability diagrams revisited.
Environmental Science & Technology. 2004;38:3641–8.
Kirk, M.F., Holm, T.R., Park, J., Jin, Q., Sanford, R.A., Fouke, B.W., Bethke, C.M.,
2004. Bacterial sulfate reduction limits natural arsenic contamination in
groundwater. Geology. 32(11), 953.
Kroopnick, P.M., Craig, H., 1972. Atmospheric oxygen: Isotopic composition and
solubility fractionation. Science. 175(4017), 54-55.
Krouse, H.R., Mayer, B., 2000. Sulphur and oxygen isotopes in sulphate. In: Cook, P., Herczeg,
A.L. (Eds.), Environmental Tracers in Subsurface Hydrology. Kluwer Academic Publishers,
pp. 195–231.
Kumar, S., Nicholas, D.J.D., Williams, E.H., 1983. Definitive 15N NMR evidence that
water serves as a source of ‘O’ during nitrite oxidation by Nitrobacter agilis. FEBS
Letters. 152(1), 71-74.
Kurosawa, K., Egashira, K., Masakazu, T., Jahiruddin, M., Abu Zofar, M., Moslehuddin,
Zulfikar Rahman, M., 2008. Variation in arsenic concentration relative to ammonium
nitrogen and oxidation reduction potential in surface and groundwater. Commun. Soil. Sci.
Plan. 39, 1467-1475.
Liu, C.W., Lin, K.H., Kuo, Y.M., 2003. Application of factor analysis in the assessment
of groundwater quality in a blackfoot disease area in Taiwan. Science of The Total
Environment. 313(1-3), 77-89.
Liu CW, Wang CJ, Kao YH. Assessing and simulating the major pathway and hydrogeochemical
transport of arsenic in the Beitou–Guandu area, Taiwan. Environmental Geochemistry and
Health. 2016;38:219-31.
Liu, C.W., Wang, S.W., Jang, C.S., Lin, K.H., 2006. Occurrence of arsenic in ground water in
the Choushui river alluvial fan, Taiwan. J. Environ. Qual.35, 68-75.
Liu, K.K., 1984. Hydrogen and oxygen isotopic compositions of meteoric waters from the Tatun
Shan area, northern Taiwan. Bull. Inst. Earth Sci. Acad. Sin. 4, 159-175.
Liu, C.W., Lin, K.H., Kuo, Y.M., 2003. Application of factor analysis in the assessment of
groundwater quality in a blackfoot disease area in Taiwan. Sci. Total Environ. 313, 77-89.
Lu, K.L., Liu, C.W., Liao, V.H.C., Liao, C.M., 2016. Distinct function of metal-reducing
bacteria from sediment and groundwater in controlling the arsenic mobilization in
sedimentary aquifer. Journal of Bioremediation & Biodegradation. 07(01).
Lu, K.L., Liu, C.W., Wang, S.W., Jang, C.S., Lin, K.H., Liao, V.H.C., Laio, C.M., Chang,
F.J., 2010. Primary sink and source of geogenic arsenic in sedimentary aquifers in
the southern Choushui River alluvial fan, Taiwan. Applied Geochemistry. 25(5),
684-695.
Mapoma HWT, Xie X, Pi K, Liu Y, Zhu Y. Understanding arsenic mobilization using
reactive transport modeling of groundwater hydrochemistry in the Datong basin
study plot, China. Environmental Science Process & Impacts. 2016;18:371-85.
Mariotti, A., Landreau, A., Simon, B., 1988. 15N isotope biogeochemistry and natural
denitrification process in groundwater: Application to the chalk aquifer of northern
France. Geochimica et Cosmochimica Acta. 52(7), 1869-1878.
Mayorga, P., Moyano, A., Anawar, H.M., García-Sánchez, A., 2013. Temporal variation
of arsenic and nitrate content in groundwater of the Duero River Basin (Spain).
Physics and Chemistry of the Earth, Parts A/B/C. 58-60, 22-7.
Mengis, M., Schif, S.L., Harris, M., English, M.C., Aravena, R., Elgood, R.J., Maclean,
A., 1999. Multiple geochemical and isotopic approaches for assessing ground water
NO3- elimination in a riparian zone. Ground Water. 37(3), 448-457.
Michener, R.H.E., Lajtha, K.E., 2007. Stable Isotopes in Ecology and Environmental
Science. Kendall C, Elliott EM, Wankel SD, editors: Blackwell Publishing,
Hoboken, New Jersey. 375-449 p.
Montoya, J.P., Korrigan, S.G., McCarthy, J.J., 1991. Rapid, storm-induced changes in
the natural abundance of 15N in a planktonic ecosystem, Chesapeake Bay, USA.
Geochimica et Cosmochimica Acta. 55(12), 3627-3638.
Mukherjee, A., Sengupta, M.K., Hossain, M.A., Ahamed, S., Das, B., Nayak, B., Lodh, D.,
Rahman, M.M., Chakraborti, D., 2006. Arsenic contamination in groundwater: a global
perspective with emphasis on Asian scenario. J. Health Popul. Nutr. 24, 142-163.
Nickson, R.T., McArthur, J.M., Ravenscroft, P., Burgess, W.G., Ahmed, K.M., 2000.
Mechanism of arsenic release to groundwater, Bangladesh and West Bengal.
Applied Geochemistry. 15(4), 403-413.
Seiler RL, Stillings LL, Cuter N, Salonen L, Outola I. Biogeochemical factors affecting the
presence of 210Po in groundwater. Appl. Geochem 2011; 26:526–39.
Otero, N., Soler, A., Canals, À ., 2008. Controls of d34S and d18O in dissolved sulphate: Learing
from a detailed survey in the Llobregat River (Spain). Appl. Geochem. 23, 1166-1185.
Panno, S.V., Hackley, K.C., Kelly, W.R., Hwang, H.H., 2006. Isotopic evidence of
nitrate sources and denitrification in the Mississippi River, Illinois. Journal of
Environmental Quality. 35(2), 495-504.
Parkhurst DL and Appelo CAJ. User's guide to PHREEQC (version 2)--A computer
program for speciation, batch-reaction, one-dimensional transport, and inverse
geochemical calculations: U.S. Geological Survey Water-Resources Investigations
Report. 1999. 99-4259, 312 p.
Pauwels, H., Foucher, J.C., Kloppmann, W., 2000. Denitrication and mixing in a schidt
aquifer: influence on water chemistry and isotopes. Chemical Geology. 168,
307-324.
Peng, T.R., Fan, C. H., 2005. Sources and Transformations of NO3− in waters of Li-Shan
agriculture area. Soil and Environment 8, 43–58. (In Chinese)
Peng, T.R., Lin, H.J., Wang, C.H., Liu, T.S. and Kao, S.J., 2012. Pollution and variation of
stream nitrate in a protected high-mountain watershed of Central Taiwan: evidence from
nitrate concentration and nitrogen and oxygen isotope compositions. Environ. Monit.
Assess. 184, 4985-4998.
Peng, T. R., Wang, C.H., Lai, T.C., Ho F. S.K., 2007. Using hydrogen, oxygen, and tritium
isotopes to identify the hydrological factors contributing to landslides in a mountainous
area, central Taiwan, Environ. Geol. 52, 1617-1629.
Peng, T. R., Zhan, W. J., Lin, Y. U., & Liu, C. L., 2004. Evaluation of the origin and
transformation of nitrate in river water of Nantou area using the nitrogen isotope in NO3− .
Soil and Environment 7, 167–182. (In Chinese)
Peterson, M.L., Carpenter, R., 1983. Biogeochemical processes affecting total arsenic
and arsenic species distributions in an intermittently anoxic fjord. Marine
Chemistry. 12, 295-321.
Pierce, M.L., Moore, C.B., 1982. Adsorption of arsenite and arsenate on amorphous iron
hydroxide. Water Research. 16, 1247-1253.
Pi, K.F., Wang, Y.X., Xie, X.J., Huang, S.B., Yu, Q., Yu, M., 2015. Geochemical effects
of dissolved organic matter biodegradation on arsenic transport in groundwater
systems. Journal of Geochemical Exploration. 149, 8-21.
Plant, J.A., Kinniburgh, D.G., Smedley, P.L., Fordyce, F.M., Klinck, B.A., 2005. Arsenic and
Selenium. In: Lollar, B.S. (Ed.), Environmental Geochemistry, vol. 9. In: Holland, H.D.,
Turekian, K.K. (Eds.), Treatise on Geochemistry. Elsevier- Pergamon, Oxford, 17-66.
Polizzotto, M.L., Kocar, B.D., Benner, S.G., Sampson, M., Fendorf, S., 2008. Near-surface
wetland sediments as a source of arsenic release to ground water in Asia. Nature 454,
505-509.
Postma D, Larsen F, Hue NTM, Duc MT, Viet PH, Nhan PQ, et al. Arsenic in groundwater of
the Red River floodplain, Vietnam: Controlling geochemical processes and reactive
transport modeling. Geochimica et Cosmochimica Acta. 2007;71:5054-71.
Ravenscroft, P., Burgess, W.G., Ahmed, K.M., Burren, M., Perrin, J., 2005. Arsenic in
groundwater of the Bengal basin, Bangladesh: distribution, field relations, and
hydrogeologic setting. Hydrogeol. J. 13, 727-751.
Robinson, B.W., Bottrell, S.H., 1997. Discrimination of sulfur source in pristine and polluted
New Zealand river catchments using stable isotopes. Appl. Geochem. 12, 305-319.
Seiler, R.L., Stillings, L.L., Cuter, N., Salonen, L., Outola, I., 2011. Biogeochemical factors
affecting the presence of 210Po in groundwater. Appl. Geochem. 26, 526-539.
Seiler, R.L., 2005. Combined use of 15N and 18O of nitrate and 11B to evaluate nitrate
contamination in groundwater. Applied Geochemistry. 20(9), 1626-1636.
Sengupta S, Sracek O, Jean JS, Lu HY, Wang CH, Palcsu L, et al. Spatial variation of
groundwater arsenic distribution in the Chianan Plain, SW Taiwan: Role of local
hydrogeological factors and geothermal sources. Journal of Hydrology. 2014;518:393-409.
Sharp, Z., 2007. Principles of Stable Isotope Geochemistry: Pearson/Prentice Hall,
Upper Saddle River, New Jersey. 64-102.
Sigman, D.D. Casciotti, K.L. Andreani, M. Barford,C. Galanter, M. Bohlke, J. K. A Bacterial
Method for the Nitrogen Isotopic Analysis of Nitrate in Seawater and Freshwater. Anal.
Chem. 2001, 73, 4145-4153.
Smedley, P.L., Kinniburgh, D.G., 2002. A review of the source, behavior and distribution
of arsenic in natural waters. Applied Geochemistry. 17(5), 517-568.
Stüben, D., Berner, Z., Chandrasekharam, D., Karmakar, J., 2003. Arsenic enrichment in
groundwater of West Bengal, India: geochemical evidence for mobilization of As under
reducing conditions. Appl. Geochem. 18, 1417-1434.
Torssander, P., Morth, C.M., Kumpulainen, R., 2006. Chemistry and sulfur isotope investigation
of industrial wastewater contamination into groundwater aquifers, Pitea County, N. Sweden.
J. Geochem. Explor. 88, 64-67.
Swartz, C.H., Blute, N.K., Badruzzman, B., Ali, A., Brabander, D., Jay, J., Besancon, J.,
Islam, S., Hemond, H.F., Harvey, C.F., 2004. Mobility of arsenic in a Bangladesh
aquifer: Inferences from geochemical profiles, leaching data, and mineralogical
characterization. Geochimica et Cosmochimica Acta. 68(22), 4539-4557.
Umezawa, Y., Hosono, T., Onodera, S.I., Siringan, F., Buapeng, S., Delinom, R.,
Yoshimizug, C., Tayasuh, I., Nagatai, T., Taniguchia, M., 2009. Erratum to
“Sources of nitrate and ammonium contamination in groundwater under
developing Asian megacities”. Science of the Total Environment.407(9),
3219-3231.
Tekin, E., 2012. Anaerobic ammonium oxidation in groundwater contaminated by
fertilizers. Master’s thesis, University of Ottawa, Ottawa, Canada.
Thurman EM. Organic Geochemistry of Natural Waters. M. Nijhoff and W. Junk Publishers:
Dordrecht, the Netherlands, 1985.
Vitòria, L., Otero, N., Soler, A., Canals, À ., 2004. Fertilizer characterization: isotopic data (N,
S, O, C, and Sr). Environ. Sci. Technol. 38, 3254-3262.
Wang, C.H., Kuo, C.H., Peng, T.R., Chen, W.F., Chiang, C.J., Liu, W.C., Hung, J.J., 2000. Stable
isotope characteristics of Taiwan groundwaters. The symposium on Taiwan quaternary &
workshop of the Asia paleoenvironmental change project. p. 3
Wang, C.H., Peng T.R., 2001. Hydrogen and oxygen isotopic compositions of Taipei
precipitation: 1990–1998. Western Pacific Earth Sci. 1(4), 429-442.
Wang, S.W., Liu, C.W., Jang, C.S., 2007. Factors responsible for high arsenic concentrations in
two groundwater catchments in Taiwan. Appl. Geochem. 22, 460-467.
Weng TN, Liu CW, Kao YH, Hsiao SSY. Isotopic evidence of nitrogen sources and nitrogen
transformation in arsenic-contaminated groundwater. Science of the Total Environment.
2017;578:167-85
Xiong, F., Gan, Y., Duan, Y., 2015. Analysis of relationship between nitrogen and the
migration and enrichment of arsenic in groundwater in the Jianghan Plain. Safety
and Environmental Engineering. 22(2), 39-48.
Yang, W.H., Weber, K.A., Silver, W.L., 2012. Nitrogen loss from soil through anaerobic
ammonium oxidation coupled to iron reduction. Nature Geoscience. 5(8), 538-541.
Zhang, X., Sigman, D.M., Morel, F.M.M., Kraepiel, A.M.L., 2014. Nitrogen isotope
fractionation by alternative nitrogenases and past ocean anoxia. Proceedings of the
National Academy of Sciences of the United States of America. 111(13),
4782-4787.