Nitrate contamination of groundwater in the western Po Plain (Italy): the effects of groundwater and surface water interactions

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• 作者：Manuela Lasagna ; Domenico Antonio De Luca ; Elisa Franchino
• 关键词：GW–SW interactions ; Nitrates ; Losing and gaining streams ; Denitrification ; Hyporheic zone ; Riparian zone ; Po River
• 刊名：Environmental Earth Sciences
• 出版年：2016
• 出版时间：February 2016
• 年：2016
• 卷：75
• 期：3
• 全文大小：4,151 KB
• 参考文献：Agrawal GD, Lunkad SK, Malkhed T (1999) Diffuse agricultural nitrate pollution of groundwaters in India. Wat Sci Tech 39(3):67–75CrossRef
  Al-Agha MR (1999) Impact of waste water management on groundwater quality in the Gaza Strip, Palestine. In: Chilton (ed) Groundwater in the urban environment: selected city profiles. Balkema, Rotterdam, pp 77–84
  Alley WM, Reilly TE, Franke OL (1999) Sustainability of ground-water resources. U.S. Geological Survey Circular 1186, 79 pp
  Almasri MN (2007) Nitrate contamination of groundwater: a conceptual management framework. Environ Impact Asses 27(3):220–242CrossRef
  APAT-IRSA (2003) Analytical methods for waters (in Italian). Serie APAT Manuali e Linee Guida 29/2003. APAT, Rome
  Baker L (1992) Introduction to nonpoint source pollution in the United States and prospects for wetland use. Ecol Eng 1:1–26CrossRef
  Baker MA, Vervier P (2004) Hydrological variability, organic matter supply and denitrification in the Garonne River ecosystem. Freshw Biol 49:181–190CrossRef
  Balestrini R, Arese C, Delconte C (2006) Nitrogen removal in a freshwater riparian wetland: an example from italian lowland spring. Verh Int Ver Limnol 29(5):2217–2220
  Balestrini R, Arese C, Delconte CA, Lotti A, Salerno F (2011) Nitrogen removal in subsurface water by narrow buffer strips in the intensive farming landscape of the Po River watershed, Italy. Ecol Eng 37:148–157CrossRef
  Bassanino M, Sacco D, Zavattaro L, Grignani C (2011) Nutrient balance as a sustainability indicator of different agro-environments in Italy. Ecol Indic 11:715–723CrossRef
  Bayani Cardenas M (2009) Stream-aquifer interactions and hyporheic exchange in gaining and losing sinuous streams. Water Resour Res 45:W06429. doi:10.​1029/​2008WR007651
  Bertrand G, Siergieiev D, Ala-Aho P, Rossi PM (2014) Environmental tracers and indicators bringing together groundwater, surface water and groundwater-dependent ecosystems: importance of scale in choosing relevant tools. Environ Earth Sci 72:813–827. doi:10.​1007/​s12665-013-3005-8 CrossRef
  Böhlke JK, Denver JM (1995) Combined use of ground-water dating, chemical, and isotopic analyses to resolve the history and fate of nitrate contamination in two agricultural watersheds, atlantic coastal plain, Maryland. Water Resour Res 31:2319–2339CrossRef
  Borin M, Bigon E (2002) Abatement of NO3-N concentration in agricultural waters by narrow buffer strips. Environ Pollut 117(1):165–168CrossRef
  Bortolami GC, Maffeo B, Maradei V, Ricci B, Sorzana F (1976) Lineamenti di litologia e geoidrologia del settore piemontese della Pianura Padana. Quaderni dell’Istituto di Ricerca sulle Acque 28(1):3–37, Roma
  Botta F, De Luca DA, Lasagna M (2005) Study of the interactions between surface water and groundwater with in situ tests. In: Proceedings of the 6th international conference “Sharing a common vision of our water resources”, Menton, France, 7–10 September 2005, Paper EWRA129, 17 pp
  Bourg ACM, Bertin C (1993) Biogeochemical processes during the infiltration of river water into an alluvial aquifer. Environ Sci Technol 27:661–666CrossRef
  Bove A, Casaccio D, Destefanis E, De Luca DA, Lasagna M, Masciocco L, Ossella L, Tonussi M (2005) Idrogeologia della pianura piemontese, Regione Piemonte. Mariogros Industrie Grafiche S.p.A, Torino (CD-Rom)
  Brodie R, Sundaram B, Tottenham R, Hostetler S, Ransley T (2007) An overview of tools for assessing groundwater-surface water connectivity. Australia, Bureau of Rural Sciences, Canberra, p 131
  Bukowski J, Somers G, Bryanton J (2001) Agricultural contamination of groundwater as a possible risk factor for growth restriction or prematurity. J Occup Environ Med 43:377–383CrossRef
  Burow KR, Nolan BT, Rupert MG, Dubrovsky NM (2010) Nitrate in groundwater of the United States, 1991–2003. Environ Sci Technol 44(13):4988–4997CrossRef
  Canavese PA, De Luca DA, Masciocco L (2004) La rete di monitoraggio delle acque sotterranee delle aree di pianura della Regione Piemonte: quadro idrogeologico. Prismas: il monitoraggio delle acque sotterranee nella Regione Piemonte. Mariogros Industrie Grafiche S.p.A., Torino, 180 pp
  Chowdary VM, Rao NH, Sarma PBS (2005) Decision support framework for assessment of non-point-source pollution of groundwater in large irrigation projects. Agric Water Manag 75:194–225CrossRef
  Clement JC, Holmes RM, Peterson BJ, Pinay G (2003) Isotopic investigation of denitrification in a riparian ecosystem in western France. J Appl Ecol 40:1035–1048CrossRef
  Comazzi M, De Luca DA, Masciocco L, Zuppi GM (1988) Lineamenti idrogeologici del Piemonte. In: “Studi Idrogeologici sulla Pianura Padana”, 4, CLUP, Milano
  Dahm CN, Grimm NB, Marmonier P, Valett HM, Vervier P (1998) Nutrient dynamics at the interface between surface waters and groundwaters. Freshw Biol 40:427–451CrossRef
  De Luca DA, Lasagna M (2005) Aquifer role in reducing nitrate contamination by means of the dilution process. In: Proceedings of the 6th international conference “Sharing a common vision of our water resources”, Menton, France, 7–10 September 2005, Paper EWRA066c, 17 pp
  De Luca DA, Ossella L (2014) Assetto idrogeologico della Città di Torino e del suo hinterland. Geologia dell’Ambiente 1:10–15
  De Luca DA, Lasagna M, di Morelli di Popolo e Ticineto A (2007) Installation of a vertical slurry wall around an Italian quarry lake: complications arising and simulation of the effects on groundwater flow. Env Geol 53:177–189. doi:10.​1007/​s00254-006-0632-3 CrossRef
  De Luca DA, Destefanis E, Forno MG, Lasagna M, Masciocco L (2014) The genesis and the hydrogeological features of the Turin Po Plain fontanili, typical lowland springs in Northern Italy. Bull Eng Geol Environ 73:409–427. doi:10.​1007/​s10064-013-0527-y
  Debernardi L, De Luca DA, Lasagna M (2005) Il processo di denitrificazione naturale nelle acque sotterranee in Piemonte. In: Proceedings of AVR05 and 4th national congress on the protection and management of groundwater—Reggia di Colorno (PR), Italy, 21–23 September 2005, Paper ID 176, 27 pp
  Debernardi L, De Luca DA, Lasagna M (2008) Correlation between nitrate concentration in groundwater and parameter affecting aquifer intrinsic vulnerability. Env Geol 55:539–558. doi:10.​1007/​s00254-007-1006-1 CrossRef
  Decreto Legislativo 2 febbraio 2001, n. 31. Attuazione della direttiva 98/83/CE relativa alla qualità delle acque destinate al consumo umano. Gazz. Uff. 3 marzo 2001, n. 52—Supplemento Ordinario n. 41
  Decreto Legislativo 16 marzo 2009, n. 30. Attuazione della direttiva 2006/118/CE, relativa alla protezione delle acque sotterranee dall’inquinamento e dal deterioramento. Gazz. Uff. 4 aprile 2009, n. 79
  Deliberazione della Giunta Regionale 3 giugno 2009, n. 34-11524. Criteri tecnici per l’identificazione della base dell’acquifero superficiale e aggiornamento della cartografia contenuta nelle “Monografie delle macroaree idrogeologiche di riferimento dell’acquifero superficiale” del Piano di Tutela delle Acque, approvato con D.C.R. 117-10731 del 13/03/2007. B.U. 25 del 25 giugno 2009
  Dent CL, Grimm NB, Martı E, Edmonds JW, Henry JC, Welter JR (2007) Variability in surface-subsurface hydrologic interactions and implications for nutrient retention in an arid-land stream. J Geophys Res 112:G04004. doi:10.​1029/​2007JG000467
  Duff JH, Triska FJ (1990) Denitrification in sediments from the hyporheic zone adjacent to a small forested stream. Can J Fish Aquat Sci 47:1140–1147CrossRef
  Duff JH, Triska FJ (2000) Nitrogen biogeochemistry and surface-subsurface exchange in streams. In: Jones JB, Muholland PJ (eds) Streams and ground waters. Academic Press, Boston, pp 197–220CrossRef
  Duff JH, Murphy F, Fuller CC, Triska FJ, Harvey JW, Jackman AP (1998) A mini drivepoint sampler for measuring pore water solute concentrations in the hyporheic zone of sand-bottom streams. Limnol Oceanogr 43(6):1378–1383CrossRef
  EC (1998) Council directive 98/83/EC of 3 November 1998 on the quality of water intended for human consumption. Off J Eur Commun L 330(1998):32
  Edwardson KJ, Bowden WB, Dahm C, Morrice J (2003) The hydraulic characteristics and geochemistry of hyporheic and parafluvial zones in Arctic tundra streams, north slope, Alaska. Adv Water Resour 26(9):907–923CrossRef
  EEC (1991) Council directive 91/676/EEC of 12 December 1991 concerning the protection of waters against pollution caused by nitrates from agricultural sources. OJ L 375, 31.12.1991
  Franchino E, Lasagna M, Bucci A, De Luca DA (2014) Statistical analysis of groundwater nitrate concentrations in piedmont plain aquifers (north-western Italy). In: Prooceding of flowpath 2014—national meeting on hydrogeology, Viterbo (Italy), June 18–20, 2014, pp 62–63
  Gillham RW, Cherry JA (1978) Field evidence of denitrification in shallow groundwater flow systems. Water Pollut Res Can 13(1):53–71
  Gilliam JW (1994) Riparian wetlands and water quality. J Environ Qual 23:896–900CrossRef
  Goss MJ, Barry DAJ, Rudolph DL (1998) Contamination in Ontario farmstead domestic wells and its association with agriculture: 1. Results from drinking water wells. J Contam Hydrol 32(3–4):267–293CrossRef
  Green CT, Fisher LH, Bekins BA (2008) Nitrogen fluxes through unsaturated zones in five agricultural settings across the United States. J Environ Qual 37(3):1073–1085CrossRef
  Harter T, Davis H, Mathews M, Meyer R (2002) Shallow groundwater quality on dairy farms with irrigated forage crops. J Contam Hydrol 55:287–315CrossRef
  Harvey JW, Bencala KE (1993) The effect of streambed topography on surface-subsurface water exchange in mountain catchments. Water Resour Res 29(1):89–98. doi:10.​1029/​92WR01960 CrossRef
  Harvey JW et al (2003) Predicting changes in hydrologic retention in an evolving semi-arid alluvial stream. Adv Water Resour 26(9):939–950. doi:10.​1016/​S0309-1708(03)00085-X CrossRef
  Haycock NE, Pinay G, Walker C (1993) Nitrogen retention in river corridors: european perspectives. Ambio 22:340–346
  Hedin LO, Von Fisher JC, Ostrom NE, Kennedy BP, Brown MG, Robertson GP (1998) Thermodynamic constraints on nitrogen transformations and other biogeochemical processes at soil-stream interfaces. Ecology 79:684–703
  Hegesh E, Shiloah J (1982) Blood nitrates and infantile methemoglobinemia. Clin Chim Acta 125:107–115CrossRef
  Hill AR (1996) Nitrate removal in stream riparian zones. J Environ Qual 22:743–755CrossRef
  Hill AR (2000) Stream chemistry and riparian zones. In: Jones JB Jr, Mulholland PJ (eds) Streams and ground waters. Academic Press, San Diego
  Hill AR, Labadia CF, Sanmugadas K (1998) Hyporheic zone hydrology and nitrogen dynamics in relation to the streambed topography of a N-rich stream. Biogeochemistry 42:285–310. doi:10.​1023/​A:​1005932528748 CrossRef
  Hinkle SR, Duff JH, Triska FJ, Laenen A, Gates EB, Bencala KE, Wentz DA, Silva SR (2001) Linking hyporheic flow and nitrogen cycling near the Willametter River—a large river in Oregon, USA. J Hydrol 244:157–180CrossRef
  Holmes RM, Jones JB, Fisher SG, Grimm NB (1996) Denitrification in a nitrogen-limited stream ecosystem. Biogeochemistry 33:125–146CrossRef
  Jones JB Jr, Holmes RM (1996) Surface-subsurface interactions in stream ecosystems. Trends Ecol Evol 11:239–242CrossRef
  Jones JB Jr, Fisher SG, Grimm NB (1995) Nitrification in the hyporheic zone of a desert stream ecosystem. J North Am Benthol Soc 14:249–258CrossRef
  Jonsson K (2003) Effect of hyporheic exchange on conservative and reactive solute transport in streams. Model assessments based on tracers tests. Acta Universitatis Upsaliensis. Comprehensive summaries of Uppsala dissertations from the Faculty of Science and Technology 866. 57 pp. Uppssala
  Kalbus E, Reinstorf F, Schirmer M (2006) Measuring methods for groundwater—surface water interactions: a review. Hydrol Earth Syst Sci 10:873–887CrossRef
  Kayabalı K, Çelik M, Karatosun H, Arıgün Z, Koçbay A (1999) The influence of a heavily polluted urban river on the adjacent aquifer systems. Environ Geol 38:233–243CrossRef
  Kazezyılmaz-Alhan CM, Medina MA (2006) Stream solute transport incorporating hyporheic zone processes. J Hydrol 329(1–2):26–38CrossRef
  Kölle W, Strebel O, Böttcher J (1990) Reduced sulphur compounds in sandy aquifers and their interactions with groundwater. Groundwater monitoring and management. In: Proceedings of the Dresden symposium, March 1987. IAHS Publ. no. 173, 1990
  Korom SF (1992) Natural denitrification in the saturated zone: a review. Water Resour Res 28:1657–1668CrossRef
  Lasagna M (2006) I nitrati nelle acque sotterranee della pianura piemontese: distribuzione, origine, attenuazione e condizionamenti idrogeologici “Nitrate in Piemonte plain groundwater: distribution, origin, attenuation and hydrogeological conditioning. PhD Thesis, University of Torino, Italy, 350 pp
  Lasagna M, De Luca DA (2008) Contaminazione da nitrati nelle acque sotterranee della pianura torinese-cuneese: quadro generale e ruolo dei corsi d’acqua. Giornale di Geologia Applicata 8:75–87
  Lasagna M, De Luca DA, Sacchi E, Bonetto S (2006) Studio dell’origine dei nitrati nelle acque sotterranee piemontesi mediante gli isotopi dell’azoto. Giornale di geologia applicata 2:137–143
  Lasagna M, De Luca DA, Debernardi L, Clemente P (2009) La portata unitaria nella valutazione della capacità di attenuazione per diluizione di un acquifero (volumetric flow rate per unit perpendicular to the flow direction for the evaluation of aquifer attenuation capacity by means of the dilution process). Rendiconti Online Società Geologica Italiana 6:300–301
  Lasagna M, De Luca DA, Debernardi L, Clemente P (2013) Effect of the dilution process on the attenuation of contaminants in aquifers. Environ Earth Sci 70:2767–2784. doi:10.​1007/​s12665-013-2336-9 CrossRef
  Lasagna M, Caviglia C, De Luca DA (2014) Simulation modeling for groundwater safety in an overexploitation situation: the Maggiore Valley context (Piedmont, Italy). Bull Eng Geol Environ 73:341–355. doi:10.​1007/​s10064-013-0500-9
  Lasagna M, Franchino E, De Luca DA (2015) Areal and vertical distribution of nitrate concentration in Piedmont plain aquifers (North-western Italy). Lollino et al G (eds) Engineering geology for society and territory—volume 3, river basins, reservoir sedimentation and water resources. Springer International Publishing Switzerland 2015, pp 389–392. doi:10.​1007/​978-3-319-09054-2_​81
  Li J, Lu W, Zeng X, Yuan J, Yu F (2010) Analysis of spatial–temporal distributions of nitrate-N concentration in Shitoukoumen catchment in northeast China. Environ Monit Assess 169:335–345CrossRef
  Liao L, Green CT, Bekins BA, Böhlke JK (2012) Factors controlling nitrate fluxes in groundwater in agricultural areas. Water Resour Res 48, W00L09. doi:10.​1029/​2011WR011008
  Lowrance R, Todd R, Fail J, Hendrickson OJ, Leonard R, Asmussen L (1984) Riparian forests as nutrient filters in agricultural watersheds. Bioscience 34:374–377CrossRef
  Luca De et al (2004) PRISMAS: Il monitoraggio delle Acque Sotterranee nella Regione Piemonte. Regione Piemonte, Direzione Pianificazione Risorse Idriche. Mariogros Industrie Grafiche S.p.A, Torino
  MacQuarrie KTB, Sudicky EA, Robertson WD (2011) Numerical simulation of a fine-grained denitrification layer for removing septic system nitrate from shallow groundwater. J Contam Hydrol 52:29–55CrossRef
  Malard F, Uehlinger U, Zah R, Tockner K (2006) Flood-pulse and riverscape dynamics in a braided glacial river. Ecology 87:704–716CrossRef
  Manassaram DM, Backer LC, Messing R, Fleming LE, Luke B, Monteilh CP (2010) Nitrates in drinking water and methemoglobin levels in pregnancy: a longitudinal study. Environ Health 9:60. doi:10.​1186/​1476-069X-9-60 CrossRef
  McMahon PB, Böhlke JK (1996) Denitrification and mixing in a stream aquifer system: effects on nitrate loading to surface water. J Hydrol 186:105–128CrossRef
  Nolan B, Stoner J (2000) Nutrients in groundwaters of the conterminous United States, 1992–1995. (2000). USGS staff—published research. Paper 59. http://​digitalcommons.​unl.​edu/​usgsstaffpub/​59
  Pinay G, Haycock NE, Ruffinoni C, Holmes RM (1994) The role of denitrification in nitrogen retention in river corridors. In: Mitsch WJ (ed) Global wetlands: old world and new. Elsevier, Amsterdam, pp 107–116
  Postma D, Boesen C, Kristiansen H, Larsen F (1991) Nitrate reduction in an unconfined aquifer: water chemistry, reduction processes, and geochemical modeling. Water Resour Res 27:2027–2045CrossRef
  Pratt PF, Lund LJ, Rible JM (1978) An approach to measuring leaching of nitrate from freely drained irrigated field. In: Nitrogen environmental, vol 1. Academic Press, London
  Pretty JL, Hildrew AG, Trimmer M (2006) Nutrient dynamics in relation to surface–subsurface hydrological exchange in a groundwater fed chalk stream. J Hydrol 330(1–2):84–100
  Puckett LJ (2004) Hydrogeologic controls on the transport and fate of nitrate in ground water beneath riparian buffer zones: results from thirteen studies across the United States. Water Sci Technol 49(3):47–53
  Puckett LJ, Hughes WB (2005) Transport and fate of nitrate and pesticides: hydrogeology and riparian zone processes. J Environ Qual 34:2278–2292CrossRef
  Puckett LJ, Cowdery TK, McMahon PB, Tornes LH, Stoner JD (2002) Using chemical, hydrologic, and age dating analysis to delineate redox processes and fl ow paths in the riparian zone of a glacial outwash aquifer stream system. Water Resour Res. doi:10.​1029/​2001WR000396
  Puckett LJ, Zamora C, Essaid H, Wilson JT, Johnson HM, Brayton MJ, Vogel JR (2008) Transport and fate of nitrate at the ground-water/surface-water interface. J Environ Qual 37:1034–1050CrossRef
  Regione Piemonte (2008) Carta dell’uso del suolo 1:500000. Available at: http://​www.​regione.​piemonte.​it/​territorio/​dwd/​pianifica/​tavoloInterregio​nale/​usoSuolo.​pdf . Accessed 29 July 2015
  Rosenberry DO, LaBaugh JW (2008) Field techniques for estimating water fluxes between surface water and ground water: U.S. Geological Survey Techniques and Methods 4–D2, 128 pp
  Ruehl CR, Fisher AT, Los Huertos M, Wanke SD, Wheat CG, Kendall C, Hatch CE, Shennan C (2007) Nitrate dynamics within the Pajaro River, a nutrient-rich, losing stream. J N Am Benthol Soc 26:191–206CrossRef
  Sabater S, Butturini A, Clement J, Burt T, Dowrick D, Hefting M, Maıˆtre V, Pinay G, Postolache G, Rzepecki M, Sabater F (2003) Nitrogen removal by riparian buffers along a European climatic gradient: patterns and factors of variation. Ecosystems 6:20–30CrossRef
  Schade JD, Marti E, Welter JR, Fisher SG, Grimm NB (2002) Sources of nitrogen to the riparian zone of a desert stream: implications for riparian vegetation and nitrogen retention. Ecosystems 5:68–79CrossRef
  Seitzinger S, Harrison JA, Jk Bohlke, Bouwman AF, Lowrance R, Peterson B, Tobias C, Van Drecht G (2006) Denitrification across landscapes and waterscapes: a synthesis. Ecol Appl 16(6):2064–2090CrossRef
  Starr RC, Gillham RW (1993) Denitrification and organic carbon availability in two aquifers. Ground Water 31(6):934–947CrossRef
  Strebel O, Duynisveld WHM, Bottcher J (1989) Nitrate pollution of groundwater in western Europe. Agric Ecosyst Environ 26:189–214CrossRef
  Thorburn PJ, Biggs JS, Weier KL, Keating BA (2003) Nitrate in groundwaters of intensive agricultural areas in coastal Northeastern Australia. Agric Ecosyst Environ 94:49–58CrossRef
  Toda H, Mochizuki Y, Kawanishi T, Kawashima H (2002) Denitrification in shallow groundwater in a coastal agricultural area in Japan. Nutr Cyc Agroecosys 63:167–173CrossRef
  Triska FJ, Duff JH, Avanzino RJ (2011) Influence of exchange flow between the channel and hyporheic zone on nitrate production in a small mountain stream. Can J Fish Aquat Sci 47(11):2099–2111CrossRef
  US EPA (2000) Drinking water standards and health advisories. U.S. Environmental Protection Agency, Office of Water. EPA-822-B-00-001
  Vidon P, Hill AR (2004) Denitrification and patterns of electron donors and acceptors in eight riparian zones with contrasting hydrogeology. Biogeochemistry 71:259–283CrossRef
  Winter TC (1999) Relation of streams, lakes, and wetlands to groundwater flow systems. Hydrogeol J 7:28–45CrossRef
  Winter TC, Harvey JW, Franke OL, Alley WM (1998) Ground water and surface water—a single resource. U.S. Geological Survey Circular 1139. U.S. Government Printing Office, 1998
  Yang Z, Zhou Y, Wenninger J, Uhlenbrook S (2014) A multi-method approach to quantify groundwater/surface water-interactions in the semi-arid Hailiutu River basin, northwest China. Hydrogeol J 22:527–541CrossRef
  
• 作者单位：Manuela Lasagna (1)
  Domenico Antonio De Luca (1)
  Elisa Franchino (1)
  
  1. Earth Science Department, Turin University, Via Valperga Caluso 35, 10125, Turin, Italy
  
• 刊物类别：Earth and Environmental Science
• 刊物主题：None Assigned
• 出版者：Springer Berlin Heidelberg
• ISSN：1866-6299

文摘

This study aims to investigate the physical and chemical effects of interactions between groundwater and surface water (GW–SW)—particularly in streams—on nitrate contamination. The effects of GW–SW interactions are briefly reviewed, with a particular emphasis on processes and environments that influence increases or decreases in nitrate concentration. Then, this paper analyses nitrate concentrations in groundwater and surface water in the western Po plain (Northwestern Italy); this analysis includes the nitrate concentration profiles across the shallow aquifer and intersecting the main streams on the plain. The investigation highlights how the concentration trends are similar, even when nitrate levels in rivers and groundwater are not comparable. The maximum nitrate concentrations in the surface water were generally measured in areas with high-nitrate levels in groundwater. An analysis of the nitrate concentration profiles highlighted the mutual influences of GW–SW. The most important streams on the plain (the Po River and Stura di Demonte River), both of them gaining streams, seem to reduce the nitrate concentrations of groundwater at a study scale. The proposed conceptual model indicates how the near-stream environment (the riparian zone, wetlands, hyporheic zone and shallow organic-rich soils in the near-stream environment) and the groundwater flow systems in shallow and deep aquifers, from the recharge zone to the streams, could dramatically affect the nitrate concentrations.