NDLI: The fate and transport of nitrate in shallow groundwater in northwestern Mississippi, USA

Content Provider	SpringerLink
Author	Welch, Heather L. Green, Christopher T. Coupe, Richard H.
Copyright Year	2011
Abstract	Agricultural contamination of groundwater in northwestern Mississippi, USA, has not been studied extensively, and subsurface fluxes of agricultural chemicals have been presumed minimal. To determine the factors controlling transport of nitrate-N into the Mississippi River Valley alluvial aquifer, a study was conducted from 2006 to 2008 to estimate fluxes of water and solutes for a site in the Bogue Phalia basin (1,250 km$^{2}$). Water-quality data were collected from a shallow water-table well, a vertical profile of temporary sampling points, and a nearby irrigation well. Nitrate was detected within 4.4 m of the water table but was absent in deeper waters with evidence of reducing conditions and denitrification. Recharge estimates from 6.2 to 10.9 cm/year were quantified using water-table fluctuations, a Cl$^{–}$ tracer method, and atmospheric age-tracers. A mathematical advection-reaction model predicted similar recharge to the aquifer, and also predicted that 15% of applied nitrogen is leached into the saturated zone. With current denitrification and application rates, the nitrate-N front is expected to remain in shallow groundwater, less than 6–9 m deep. Increasing application rates resulting from intensifying agricultural demands may advance the nitrate-N front to 16–23 m, within the zone of groundwater pumping.La contamination d’origine agricole de l’eau souterraine au Nord-Ouest du Mississippi, Etats-Unis, n’a pas été étudiée de façon extensive, et les flux de produits chimiques agricoles de subsurface ont été supposés minimum. Une étude a été menée de 2006 à 2008 pour estimer les flux d’eau et de solutés sur un site du bassin de Bogue Phalia (1 250 km²), dans le but de déterminer les facteurs contrôlant le transport de l’azote dans l’aquifère alluvial du fleuve Mississippi. Des données sur la qualité des eaux ont été récoltées dans un puits peu profond, selon des points de prélèvement temporaires répartis sur un profil vertical, et dans un forage d’irrigation voisin. Les nitrates ont été détectés jusqu’à 4.4 m sous le niveau statique, mais étaient absents dans les eaux plus profondes, avec des indices de réduction et de dénitrification. Les recharges ont été estimées entre 6.2 et 10.9 m/an en utilisant les fluctuations de la surface libre, une méthode de traçage par les chlorures, et des traceurs atmosphériques de datation. Un modèle mathématique d’advection-réaction a prédit à une recharge similaire, estimant aussi que 15% de l’azote introduit est lessivé vers la zone saturée. Avec les taux actuels de dénitrification et d’application d’intrants, le front de nitrate N devrait se maintenir en eau peu profonde à moins de 6–9 m de profondeur. L’augmentation des taux d’intrants liée à une intensification des pratiques agricoles pourrait repousser le front azoté à 16–23 m, à l’intérieur de la zone de pompage.La contaminación agrícola del agua subterránea en el noroeste de Mississippi, EEUU, no ha sido estudiada extensamente, y los flujos subsuperficiales de los agroquímicos agrícolas se han presumidos mínimos. Para determinar los factores que controlan el transporte de nitrato-N en el acuífero aluvial del valle del Río Mississippi, se llevó a cabo un estudio desde 2006 a 2008 para estimar los flujos de agua y solutos para un sitio en la cuenca Bogue Phalia (1,250 km$^{2}$). Los datos de calidad del agua se recolectaron a partir de pozos freáticos someros, un perfil vertical de puntos de muestreo temporario, y un pozo de riego cercano. El nitrato se detectó dentro de los 4.4 m de la capa freática pero estaba ausente en aguas más profundas con evidencias de condiciones reductoras y desnitrificación. Se cuantificó la estimación de la recarga en 6.2 a 10.9 cm/año usando las fluctuaciones del nivel freático, el método de trazador de Cl$^{–}$ y trazadores de edad atmosférica. Un modelo matemático de advección – reacción predijo una recarga similar al acuífero, y también predijo que el 15% del nitrógeno aplicado es lixiviado dentro de la zona saturada. Con los ritmos de desnitrificación y aplicación actuales se espera que el frente de nitrato-N permanezca en el agua subterránea somera, a un profundidad menor a 6–9 m de profundidad. Los ritmos de aplicación crecientes provenientes de la demanda de la agricultura intensiva puede llevar el frente de nitrato-N a 16–23 m, dentro de la zona del bombeo de agua subterránea.美国密西西比州西北部地下水的农业污染并没有进行过系统的研究,地下农用化学物的通量据推测是非常小的。为了确定控制密西西比河谷冲积扇含水层里硝酸盐-氮运移的因素,2006–2008年开展了估算Bogue Phalia盆地(1250 km$^{2}$)某地点水和溶质通量的研究。水质数据来自于潜水含水层中的井孔、临时取样点的垂向剖面以及附近一个灌溉井。硝酸盐在水位以下4.4m内被检测到,而在更深的水里则没有硝酸盐存在,有证据表明后者处于还原环境并存在反硝化作用。根据水位波动,采用Cl–示踪方法以及大气中的年龄示踪剂确定出地下水补给量为6.2 – 10.9 cm/year。流动-反应数值模型预测的该含水层补给量结果与此相似,并估测了15%的人工氮淋滤到了饱和带中。按照目前的反硝化作用强度和施肥速率,硝酸盐-氮锋面将会局限于浅部地下水中,埋深小于6–9 m。不断扩大的农业规模导致的施肥量增加可能在地下水开采区使硝酸盐锋面下移至地下16–23m处。A contaminação agrícola das águas subterrâneas no noroeste do Mississippi, nos EUA, não tem sido estudada de forma extensiva, e tem-se presumido que o transporte subterrâneo de agroquímicos é mínimo. Para determinar os factores que controlam a entrada de nitrato-N no aquífero aluvionar do Vale do Rio Mississippi, realizou-se um estudo, entre 2006 e 2008, para estimar os fluxos de água e solutos numa zona da bacia Bogue Phalia (1,250 km$^{2}$). Foram recolhidos dados de qualidade da água de um poço pouco profundo que capta o nível freático, de um perfil vertical de pontos de amostragem temporários e ainda de um furo de rega localizado próximo. Os nitratos foram detectados até 4.4 m abaixo do nível freático, mas estavam ausentes em águas mais profundas, evidenciando condições redutoras e desnitrificação. Obtiveram-se estimativas de recarga entre 6.2 e 10.9 cm/ano com base nas oscilações do nível freático, no método do traçador Cl$^{–}$ e nos traçadores atmosféricas usados para datação. Um modelo matemático de advecção-reacção previu uma recarga do aquífero semelhante, e também previu que 15% do azoto aplicado é lixiviado para dentro da zona saturada. Com as actuais taxas de desnitrificação e aplicação, a frente do nitrato-N deverá permanecer nas águas subterrâneas menos profundas, a menos de 6–9 m de profundidade. O aumento das taxas de aplicação que resultam da intensificação da procura agrícola pode causar o avanço da frente de nitrato-N até 16–23 m, dentro da zona de captação das águas subterrâneas.
Starting Page	1239
Ending Page	1252
Page Count	14
File Format	PDF
ISSN	14312174
Journal	Hydrogeology Journal
Volume Number	19
Issue Number	6
e-ISSN	14350157
Language	Portuguese
Publisher	Springer-Verlag
Publisher Date	2011-06-28
Publisher Institution	International Association of Hydrogeologists
Publisher Place	Berlin, Heidelberg
Access Restriction	Subscribed
Subject Keyword	Groundwater age Nitrate Recharge Geochemical modeling USA Geology Hydrogeology Waste Water Technology Water Pollution Control Water Management Aquatic Pollution
Content Type	Text
Resource Type	Article
Subject	Water Science and Technology Earth and Planetary Sciences

Sl.	Authority	Responsibilities	Communication Details
1	Ministry of Education (GoI), Department of Higher Education	Sanctioning Authority	https://www.education.gov.in/ict-initiatives
2	Indian Institute of Technology Kharagpur	Host Institute of the Project: The host institute of the project is responsible for providing infrastructure support and hosting the project	https://www.iitkgp.ac.in
3	National Digital Library of India Office, Indian Institute of Technology Kharagpur	The administrative and infrastructural headquarters of the project	Dr. B. Sutradhar bsutra@ndl.gov.in
4	Project PI / Joint PI	Principal Investigator and Joint Principal Investigators of the project	Dr. B. Sutradhar bsutra@ndl.gov.in Prof. Saswat Chakrabarti will be added soon
5	Website/Portal (Helpdesk)	Queries regarding NDLI and its services	support@ndl.gov.in
6	Contents and Copyright Issues	Queries related to content curation and copyright issues	content@ndl.gov.in
7	National Digital Libarray of India Club (NDLI Club)	Queries related to NDLI Club formation, support, user awareness program, seminar/symposium, collaboration, social media, promotion, and outreach	clubsupport@ndl.gov.in
8	Digital Preservation Centre (DPC)	Assistance with digitizing and archiving copyright-free printed books	dpc@ndl.gov.in
9	IDR Setup or Support	Queries related to establishment and support of Institutional Digital Repository (IDR) and IDR workshops	idr@ndl.gov.in

Investigating local variation in groundwater recharge along a topographic gradient, Walnut Creek, Iowa, USA

Mountain-block recharge, present and past, in the eastern Española Basin, New Mexico, USA

A comparison of recharge rates in aquifers of the United States based on groundwater-age data

Comparative study of climate-change scenarios on groundwater recharge, southwestern Mississippi and southeastern Louisiana, USA

Mapping mean annual groundwater recharge in the Nebraska Sand Hills, USA

Calibration of models using groundwater age

Groundwater movement, recharge, and perchlorate occurrence in a faulted alluvial aquifer in California (USA)

Groundwater flood of a river terrace in southwest Wisconsin, USA

Review: Recharge rates and chemistry beneath playas of the High Plains aquifer, USA

The fate and transport of nitrate in shallow groundwater in northwestern Mississippi, USA

Similar Documents

Investigating local variation in groundwater recharge along a topographic gradient, Walnut Creek, Iowa, USA

Mountain-block recharge, present and past, in the eastern Española Basin, New Mexico, USA

A comparison of recharge rates in aquifers of the United States based on groundwater-age data

Comparative study of climate-change scenarios on groundwater recharge, southwestern Mississippi and southeastern Louisiana, USA

Mapping mean annual groundwater recharge in the Nebraska Sand Hills, USA

Calibration of models using groundwater age

Groundwater movement, recharge, and perchlorate occurrence in a faulted alluvial aquifer in California (USA)

Groundwater flood of a river terrace in southwest Wisconsin, USA

Review: Recharge rates and chemistry beneath playas of the High Plains aquifer, USA

The fate and transport of nitrate in shallow groundwater in northwestern Mississippi, USA