Trends and Transformation of Nutrients and Pesticides in a Coastal Plain Aquifer System, United States

Denver, Judith M.; Tesoriero, Anthony J.; Barbaro, Jeffrey R.

doi:10.2134/jeq2009.0107

Cited by 29 publications

(46 citation statements)

References 46 publications

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“…In addition, the resulting stream water attenuated nitrate-N concentration relative to the groundwater without evidence for MESA diminishment (data not shown). These observations in conjunction with previous studies (Denver et al, 2010;Phillips et al, 1999;Steele et al, 2008;McConnell et al, 2007) indicate that 1) MESA is stable even in anaerobic …”

Section: Mesa and Nitrate-n Fate In An Anaerobic Environmentsupporting

confidence: 88%

“…As shown above and elsewhere (Denver et al, 2010;McConnell et al, 2007;Phillips et al, 1999;Steele et al, 2008), MESA is a stable, soluble indicator for agricultural waters and has a long half-life in surface waters (Huntscha et al, 2008). The residence time of waters in the Choptank River estuary has been estimated to be 19 days (Bricker et al, 2007).…”

Section: Mesa As An Indicator Of Agricultural Water In the Estuarymentioning

confidence: 87%

“…Nitrate-N concentrations were positively correlated with percent cropland area, whereas MESA concentrations were surprisingly unrelated to percent cropland area (Hively et al, 2011), which suggests that additional factors, such as differences in drainage and geomorphology, may be influencing the delivery of agricultural waters to the sampling sites. Multivariate analyses of these data (Hively et al, 2011) along with prior regional studies Böhlke and Denver, 1995;Denver et al, 2010;Phillips et al, 1993) have suggested that multiple factors influence nitrate-N concentrations in the stream waters. Agricultural drainage, percentages of agricultural, forested, developed and conservation reserve lands, and percentages of hydric soils and forested wetlands were examined, but in these previous analyses, no definitive causal relationships were discernible among these factors.…”

Section: Mesa and Nitrate-n Concentrations In The Subwatershedsmentioning

confidence: 99%

“…Pollutant fate and transport can vary temporally and spatially because different vadose zone and groundwater sources containing pollutants move, interact with the environmental matrix, are transformed, and respond to changing climatic conditions (Denver et al, 2010;Phillips and Bachman, 1996). Identifying an agricultural indicator can provide an essential frame of reference for analysis.…”

Section: Introductionmentioning

confidence: 99%

“…In contrast to nitrate-N, once MESA enters ground water, it is very stable (Phillips Table 1 Conceptual model of landscape characteristics that influence transport, processing, and delivery of nitrate-N and MESA to headwater streams of the Choptank River (Ator et al, 2005;Bachman and Phillips, 1996;Denver et al, 2010, in press;Phillips and Bachman, 1996;Phillips et al, 1993 Steele et al, 2008); MESA persists over decadal time scales (Denver et al, 2010). In surface water, the modeled half-life for all MESA processing (phototransformation, transport, etc.)…”

Section: Introductionmentioning

confidence: 99%

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Metolachlor metabolite (MESA) reveals agricultural nitrate-N fate and transport in Choptank River watershed

McCarty

Hapeman

Rice

et al. 2014

Science of The Total Environment

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Section: Mesa and Nitrate-n Fate In An Anaerobic Environmentsupporting

confidence: 88%

Section: Mesa As An Indicator Of Agricultural Water In the Estuarymentioning

confidence: 87%

Section: Mesa and Nitrate-n Concentrations In The Subwatershedsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Metolachlor metabolite (MESA) reveals agricultural nitrate-N fate and transport in Choptank River watershed

McCarty

Hapeman

Rice

et al. 2014

Science of The Total Environment

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Quantifying an aquifer nitrate budget and future nitrate discharge using field data from streambeds and well nests

Gilmore

Genereux

Solomon

et al. 2016

Water Resources Research

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Novel groundwater sampling (age, flux, and nitrate) carried out beneath a streambed and in wells was used to estimate (1) the current rate of change of nitrate storage, dSNO3/dt, in a contaminated unconfined aquifer, and (2) future [ NO3−]FWM (the flow‐weighted mean nitrate concentration in groundwater discharge) and fNO3 (the nitrate flux from aquifer to stream). Estimates of dSNO3/dt suggested that at the time of sampling (2013) the nitrate storage in the aquifer was decreasing at an annual rate (mean = −9 mmol/m2yr) equal to about one‐tenth the rate of nitrate input by recharge. This is consistent with data showing a slow decrease in the [ NO3−] of groundwater recharge in recent years. Regarding future [ NO3−]FWM and fNO3, predictions based on well data show an immediate decrease that becomes more rapid after ∼5 years before leveling out in the early 2040s. Predictions based on streambed data generally show an increase in future [ NO3−]FWM and fNO3 until the late 2020s, followed by a decrease before leveling out in the 2040s. Differences show the potential value of using information directly from the groundwater—surface water interface to quantify the future impact of groundwater nitrate on surface water quality. The choice of denitrification kinetics was similarly important; compared to zero‐order kinetics, a first‐order rate law levels out estimates of future [ NO3−]FWM and fNO3 (lower peak, higher minimum) as legacy nitrate is flushed from the aquifer. Major fundamental questions about nonpoint‐source aquifer contamination can be answered without a complex numerical model or long‐term monitoring program.

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Factors driving nutrient trends in streams of the Chesapeake Bay watershed

Ator¹,

Blomquist²,

Webber³

et al. 2020

J of Env Quality

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Despite decades of effort toward reducing nitrogen and phosphorus flux to Chesapeake Bay, water-quality and ecological responses in surface waters have been mixed. Recent research, however, provides useful insight into multiple factors complicating the understanding of nutrient trends in bay tributaries, which we review in this paper, as we approach a 2025 total maximum daily load (TMDL) management deadline. Improvements in water quality in many streams are attributable to management actions that reduced point sources and atmospheric nitrogen deposition and to changes in climate. Nutrient reductions expected from management actions, however, have not been fully realized in watershed streams. Nitrogen from urban nonpoint sources has declined, although waterquality responses to urbanization in individual streams vary depending on predevelopment land use. Evolving agriculture, the largest watershed source of nutrients, has likely contributed to local nutrient trends but has not affected substantial changes in flux to the bay. Changing average nitrogen yields from farmland underlain by carbonate rocks, however, may suggest future trends in other areas under similar management, climatic, or other influences, although drivers of these changes remain unclear. Regardless of upstream trends, phosphorus flux to the bay from its largest tributary has increased due to sediment infill in the Conowingo Reservoir. In general, recent research emphasizes the utility of input reductions over attempts to manage nutrient fate and transport at limiting nutrients in surface waters. Ongoing research opportunities include evaluating effects of climate change and conservation practices over time and space and developing tools to disentangle and evaluate multiple influences on regional water quality.

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Trends and Transformation of Nutrients and Pesticides in a Coastal Plain Aquifer System, United States

Cited by 29 publications

References 46 publications

Metolachlor metabolite (MESA) reveals agricultural nitrate-N fate and transport in Choptank River watershed

Metolachlor metabolite (MESA) reveals agricultural nitrate-N fate and transport in Choptank River watershed

Quantifying an aquifer nitrate budget and future nitrate discharge using field data from streambeds and well nests

Factors driving nutrient trends in streams of the Chesapeake Bay watershed

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