Nonpoint Nitrate Contamination of Ground Water in Merrick County, Nebraska<sup>a</sup>

Spalding, Roy F.; Gormly, James R.; Curtiss, B. H.; Exner, Mary E.

doi:10.1111/j.1745-6584.1978.tb03207.x

Cited by 43 publications

(18 citation statements)

References 5 publications

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“…The study site is located five miles northwest of Central City in Merrick County, Nebraska (Exhibit 1). Since the 1970s, Merrick County groundwater has been known to have high and consistent nitrate concentrations (Spalding et al, 1978).The δ15N values of nitrate in groundwater at this site confirmed that the primary nitrate source is commercial fertilizer leachates (Bates & Spalding, 1998).…”

Section: Site Description and Hydrogeologymentioning

confidence: 53%

“…The aquifer is unconfined and composed of fluvial sand and gravel material deposited in the Quaternary (Pleistocene) (Spalding et al, 1978). Particle size analysis of the aquifer matrix collected from denitrification zone (depth 36-48 feet) with a Geo-probe™ showed that aquifer material is composed of 29 percent gravel, 44 percent coarse sand, 26 percent medium to fine sand, and 1 percent silts plus clays.The sand has an effective diameter (d 10 ) of 0.25 mm and a uniformity coefficient (U = d 60 /d 10 ) of 6, which specifies the non-uniformity in the grain size of aquifer material.…”

Section: Site Description and Hydrogeologymentioning

confidence: 99%

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Development of a procedure for sustainable in situ aquifer denitrification

Khan

Spalding

2003

Remediation Journal

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INTRODUCTIONNitrate is the most pervasive contaminant in groundwater in the United States and throughout the world. In Nebraska, more than 85 percent of the population relies on groundwater for drinking water and more than 20 percent of the domestic wells have nitrate concentrations that exceed the drinking water standard (Spalding & Exner, 1993). In drinking water, nitrate is reported to cause methemoglobinemia or blue-baby syndrome (Walton, 1951) in infants and bladder cancer in women (Weyer et al., 2001).Many rural communities have wells that exceed the maximum contaminant level (MCL) of 10 mg NO 3-N l -1 and find available above-ground treatment alternatives economically prohibitive. Above-ground physical/chemical processes such as ion exchange, reverse osmosis, and electrodialysis do not detoxify nitrate, are very expensive, and generate hazardous brine waste that must be disposed off in a secure landfill at additional cost (Rogalla et al., 1991;Bouwer & Crowe, 1982). Biodenitrification is the only process that can specifically target nitrate and convert this anion to innocuous end product. IN SITU DENITRIFICATIONEnhanced in situ biodenitrification (EISBD) is an emerging technology that offers a cost-effective and environmental friendly solution to the nitrate contamination problem (ITRC, 2000). In this study, in situ injection relies on a daisy well system, which constitutes a series of injection wells arranged in a circular pattern around the contaminated well (extraction well) to deliver the needed carbon substrate directly into the nitrate-contaminated zone; whereas the remediated water will be captured by the extraction well. Simultaneous extraction and injection in this configuration creates a pattern of groundwater flow radiating from higher water levels at the injection wells to lower levels created by drawdown at the extraction well. During operation, the water table assumes a configuration that is depicted as being similar to the petals of a daisy flower.When sufficient organic substrate is injected into the groundwater, endemic nitrate degrading microbes (denitrifiers) proliferate in the denitrified zones (DNZ) and enzymatically reduce nitrate to harmless nitrogen gas as follows:Attempts at in situ denitrification have been reported throughout the world with various degrees of success ( McMahon et al., 1998;Nuttall, 1997;Hammon & Fustec, 1991;Kruithof et al., 1985;Janda et al., 1988;Mercado et al., 1988;Braester & Martinell, 1988;Chalupa, 1985). Nitrate removal rates varied from as little as 10 percent to almost complete removal. However, in most cases the performance of the denitrification process was impaired by the excessive and rapid biomass growth in the immediate vicinity of the injection well.This resulted in clogging and rendered the injection well inoperable. Recent researches (Semprini et al., 1988;Shouche et al., 1993;Peyton, 1996;Khan, 2000) suggested that a nutrient pulsing technique minimized biofouling at the injection well. However, these studies were limited to computer simulatio...

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Section: Site Description and Hydrogeologymentioning

confidence: 53%

Section: Site Description and Hydrogeologymentioning

confidence: 99%

Development of a procedure for sustainable in situ aquifer denitrification

Khan

Spalding

2003

Remediation Journal

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“…The presence of large tracts of continuous corn production in this area results in intensive use of N fertilizer and irrigation water. Groundwater studies as early as the 1950s documented the presence of nitrates in this Platte River alluvial aquifer [3]. Succeeding studies noted the steady rise in groundwater N levels over the next 30 years to about double the U.S. Environmental Protection Agencys (EPA) safe drinking water standard of 10 mg/l (Fig.…”

Section: Water Quality Managment In the Central Platte Valleymentioning

confidence: 98%

Nutrient Management Programs, Nitrogen Fertilizer Practices, and Groundwater Quality in Nebraska’s Central Platte Valley (U.S.), 1989–1998

Daberkow¹,

Taylor²,

Gollehon³

et al. 2001

The Scientific World JOURNAL

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Given the societal concern about groundwater pollution from agricultural sources, public programs have been proposed or implemented to change farmer behavior with respect to nutrient use and management. However, few of these programs designed to change farmer behavior have been evaluated due to the lack of detailed data over an appropriate time frame. The Central Platte Natural Resources District (CPNRD) in Nebraska has identified an intensively cultivated, irrigated area with average groundwater nitrate-nitrogen (N) levels about double the EPA's safe drinking water standard. The CPNRD implemented a joint education and regulatory N management program in the mid-1980s to reduce groundwater N. This analysis reports N use and management, yield, and groundwater nitrate trends in the CPNRD for nearly 3000 continuous-corn fields from 1989 to 1998, where producers faced limits on the timing of N fertilizer application but no limits on amounts. Groundwater nitrate levels showed modest improvement over the 10 years of this analysis, falling from the 1989-1993 average of 18.9 to 18.1 mg/l during 1994-1998. The availability of N in excess of crop needs was clearly documented by the CPNRD data and was related to optimistic yield goals, irrigation water use above expected levels, and lack of adherence to commercial fertilizer application guidelines. Over the 10-year period of this analysis, producers reported harvesting an annual average of 9729 kg/ha, 1569 kg/ha (14%) below the average yield goal. During 1989-1998, producers reported annually applying an average of 162.5 kg/ha of commercial N fertilizer, 15.7 kg/ ha (10%) above the guideline level. Including the N contribution from irrigation water, the potential N contribution to the environment (total N available less estimated crop use) was estimated at 71.7 kg/ha. This is an estimate of the nitrates available for denitrification, volatilization, runoff, future soil N, and leaching to groundwater. On average, between 1989-1993 and 1994-1998, producers more closely followed CPNRD N fertilizer recommendations and increased their use of postemerge N applications -an indication of improved synchrony between N availability and crop uptake. INTRODUCTIONNitrate contamination of ground-and surface water has long been recognized as a risk to human health and the environment [1]. In response to these risks, the U.S. has enacted a number of policies to reduce water pollution, including the Clean Water Act, the Safe Drinking Water Act, the Wellhead Protection Program, the Source Water Assessment Program, and the Sole Source Aquifer Protection Program. While federal policies may set national standards for water quality (e.g., 10 mg/l for N in drinking water), states and local areas often have the responsibility to develop and implement water quality programs to meet those standards. Given the regional variability in natural resources and economic activity, state and local jurisdictions, rather than federal agencies, may be able to more efficiently design and implement programs to ma...

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“…Indeed, rising groundwater nitrate levels have been correlated with land use in several other studies as well. Specifically, high nitrate concentrations have been measured in the vadose zone and in shallow aquifer wells below well-drained cropland soils (Spaldingb et al 1978;Sophocleous 1990). Nitrate movement through soils into shallow aquifers has been shown to be directly correlated to precipitation, irrigation, and rate of N-fertilizer application.…”

Section: Chapter 2 -Background Great Bend Prairie Aquifermentioning

confidence: 99%

“…Below well-drained cropland soils, high nitrate concentrations have been measured in the intermediate vadose zone and in shallow aquifer wells (Spalding 1984;Spalding and Kitchen 1988). Mobility of nitrate in soil, irrigation and Nfertilizer application rates, and soil texture contribute to the rapid movement of nitrate into and attenuation of nitrate within underlying water table aquifers (Spaldingb et al 1978;Lasagna et al 2016).…”

Section: Chapter 1 -Introductionmentioning

confidence: 99%

Impact of Land Use on Microbial Communities in the Great Bend Prairie Aquifer

Richardson¹

2019

Geological Society of America Abstracts With Programs

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The High Plains aquifer is a vital source of irrigation and drinking water in the central United States. Aquifer geochemistry and water quality can be significantly affected by microbially mediated redox reactions. Therefore, it is important to understand how environmental controls on aquifer microbial communities affect the health of the aquifer. This study examines the relationship between land use and aquifer microbiology in the Great Bend Prairie aquifer, a portion of the High Plains aquifer in south-central Kansas. In the summer of 2018, we collected samples from soils of different land use near groundwater monitoring wells that were sampled two years prior. The soil samples were collected in replicates of four at each well site, and the groundwater was sampled from wells screened in the shallow and deep aquifer at each site. Results demonstrate significant variation in nitrate levels with land use in both soils and groundwater. Soil extractable NO3-N in irrigated crop soils is significantly higher (86.05 mg/kg) than in pasture (3.84 mg/kg) and non-irrigated crop (29.48 mg/kg) soils on average. Shallow wells below crop soils contain average NO3-N concentrations three times higher than those of the shallow wells below pasture soils and of the deep wells, at 18 mg/L. Coupled with this impact, microbial community composition also varies significantly with land use in both soils and groundwater. Our statistical analysis shows that NO3-N and soil microbial communities are significantly correlated, with land use as the best defining factor in soil community similarity.Groundwater microbial communities were significantly correlated with land use and geographic markers, with well depth as the best defining factor in groundwater microbial community.Specifically, the aquifer contains many genera capable of participating in the nitrification and denitrification processes, including genera within bacterial orders Nitrospirales (nitrification) and Pseudomonadales (denitrification), as well as archaeal phylum Crenarchaeota (nitrification and nitrite reduction). Shallow crop wells have the highest average relative abundances of Pseudomonadales (12.14% ) and Nitrospirales (7.03%), compared to other wells. Deep crop wells have the highest average relative abundances of Crenarchaeota (3.25%). Taken together, our results show that land use not only affects the chemistry and microbiology of soils but also the underlying water table aquifer. These findings advance our understanding of environmental controls on aquifer microbiology. v

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Nonpoint Nitrate Contamination of Ground Water in Merrick County, Nebraska^a

Cited by 43 publications

References 5 publications

Development of a procedure for sustainable in situ aquifer denitrification

Development of a procedure for sustainable in situ aquifer denitrification

Nutrient Management Programs, Nitrogen Fertilizer Practices, and Groundwater Quality in Nebraska’s Central Platte Valley (U.S.), 1989–1998

Impact of Land Use on Microbial Communities in the Great Bend Prairie Aquifer

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Nonpoint Nitrate Contamination of Ground Water in Merrick County, Nebraskaa

Cited by 43 publications

References 5 publications

Development of a procedure for sustainable in situ aquifer denitrification

Development of a procedure for sustainable in situ aquifer denitrification

Nutrient Management Programs, Nitrogen Fertilizer Practices, and Groundwater Quality in Nebraska’s Central Platte Valley (U.S.), 1989–1998

Impact of Land Use on Microbial Communities in the Great Bend Prairie Aquifer

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Nonpoint Nitrate Contamination of Ground Water in Merrick County, Nebraska^a