Inputs, Transformations, and Transport of Nitrogen and Phosphorus in Chesapeake Bay and Selected Tributaries

Boynton, Walter R.; Garber, Jonathan; Summers, Robert M.; Kemp, William

doi:10.2307/1352640

Cited by 525 publications

(359 citation statements)

References 46 publications

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“…1). The watershed drains to a 137-km 2 subestuary of Chesapeake Bay (Boynton et al 1995;Hagy et al 2000). The northwestern 28% of the watershed is in the Piedmont physiographic province and the remainder is in the Coastal Plain (Langland et al 1995).…”

Section: Watershed Datamentioning

confidence: 99%

“…During the first, relatively wet year of our study, PS supplied 5% of the water, 22% of the N, and 7% of the P delivered to the estuary . In the second, drier year, PS were more important, supplying 14% of the water, 46% of the N, and 34% of the P. PS were formerly the largest sources of N and P, but improved treatment methods have reduced nutrient concentrations in wastewater discharges and NPS discharges are now dominant (Boynton et al 1995;Sprague et al 2000;D'Elia et al 2003). However, the volumes of discharge from the largest treatment plants in the watershed are still increasing (Sprague et al 2000) and will continue to do so as the watershed's population increases (D'Elia et al 2003).…”

Section: Nutrient Sources and Effects Of Watershed Changesmentioning

confidence: 99%

“…The Patuxent River, a tributary estuary of Chesapeake Bay in Maryland, is a well-studied system that has been used as a model system for testing environmental study methods and management strategies (Boynton et al 1995). In the 1960s and 1970s, the rising population of the upper watershed increased wastewater discharges to the river.…”

Section: Introductionmentioning

confidence: 99%

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Effects of land-use change on nutrient discharges from the Patuxent River watershed

et al. 2003

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ABSTRACT:We developed an empirical model integrating nonpoint source (NPS) runoff, point sources (PS), and reservoir management to predict watershed discharges of water, sediment, organic carbon, silicate, nitrogen, and phosphorus to the Patuxent River in Maryland. We estimated NPS discharges with linear models fit to measurements of weekly flow and 10 material concentrations from 22 study watersheds. The independent variables were the proportions of cropland and developed land, physiographic province (Coastal Plain or Piedmont), and time (week). All but one of the NPS models explained between 62% and 83% of the variability among concentration or flow measurements. Geographic factors (land cover and physiographic province) accounted for the explained variability in largely dissolved material concentrations (nitrate [NO 3 ], silicate [Si], and total nitrogen [TN]), but the explained variability in flow and particulates (sediment and forms of phosphorus) was more strongly related to temporal variability or its interactions with land cover and province. Average concentrations of all materials increased with cropland proportion and also with developed land (except Si), but changes in cropland produced larger concentration shifts than equivalent changes in developed land proportion. Among land cover transitions, conversions between cropland and forest-grassland cause the greatest changes in material discharges, cropland and developed land conversions are intermediate, and developed land and forest-grassland conversions have the weakest effects. Changing land cover has stronger effects on NO 3 and TN in the Piedmont than in the Coastal Plain, but for all other materials, the effects of land-use change are greater in the Coastal Plain. We predicted the changes in nutrient load to the estuary under several alternate land cover configurations, including a state planning scenario that extrapolates current patterns of population growth and land development to the year 2020. In that scenario, declines in NPS discharges from reducing cropland are balanced by NPS discharge increases from developing an area almost six times larger than the lost cropland. When PS discharges are included, there are net increases in total water, total phosphorus, and TN discharges.

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Section: Watershed Datamentioning

confidence: 99%

Section: Nutrient Sources and Effects Of Watershed Changesmentioning

confidence: 99%

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Effects of land-use change on nutrient discharges from the Patuxent River watershed

et al. 2003

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“…While field-based studies [Burns, 1998;Peterson et al, 2001;Duff et al, 2008;Mulholland et al, 2008Mulholland et al, , 2009Tank et al, 2008;Hall et al, 2009;Mulholland and Webster, 2010] and modeling approaches [Jaworski et al, 1992;Boynton et al, 1995;Alexander et al, 2000Alexander et al, , 2009Seitzinger et al, 2002;Boyer et al, 2006;Runkel, 2007;Ator and Denver, 2012] have provided much needed information on reach and watershed-scale nitrate dynamics, the limited spatial extent and/or low temporal resolution of discrete data collection continues to be a challenge for quantifying loads and interpreting drivers of change in watersheds. Recent studies have demonstrated that the collection and interpretation of high-frequency nitrate data collected using water quality sensors can be used to better quantify nitrate loads to sensitive stream and coastal environments [Ferrant et al, 2013;Bieroza et al, 2014;Pellerin et al, 2014], and provide insights into temporal nitrate dynamics that would otherwise be difficult to obtain using traditional field-based mass balance, solute injection, and/or isotopic tracer studies [Pellerin et al, 2009[Pellerin et al, , 2012Heffernan and Cohen, 2010;Sandford et al, 2013;Carey et al, 2014;Hensley et al, 2014Hensley et al, , 2015Outram et al, 2014;Crawford et al, 2015].…”

Section: Introductionmentioning

confidence: 99%

Quantifying watershed‐scale groundwater loading and in‐stream fate of nitrate using high‐frequency water quality data

Miller

Tesoriero

Capel

et al. 2016

Water Resources Research

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We describe a new approach that couples hydrograph separation with high-frequency nitrate data to quantify time-variable groundwater and runoff loading of nitrate to streams, and the net in-stream fate of nitrate at the watershed scale. The approach was applied at three sites spanning gradients in watershed size and land use in the Chesapeake Bay watershed. Results indicate that 58-73% of the annual nitrate load to the streams was groundwater-discharged nitrate. Average annual first-order nitrate loss rate constants (k) were similar to those reported in both modeling and in-stream process-based studies, and were greater at the small streams (0.06 and 0.22 day 21 ) than at the large river (0.05 day 21 ), but 11% of the annual loads were retained/lost in the small streams, compared with 23% in the large river. Larger streambed area to water volume ratios in small streams results in greater loss rates, but shorter residence times in small streams result in a smaller fraction of nitrate loads being removed than in larger streams. A seasonal evaluation of k values suggests that nitrate was retained/lost at varying rates during the growing season. Consistent with previous studies, streamflow and nitrate concentrations were inversely related to k. This new approach for interpreting high-frequency nitrate data and the associated findings furthers our ability to understand, predict, and mitigate nitrate impacts on streams and receiving waters by providing insights into temporal nitrate dynamics that would be difficult to obtain using traditional field-based studies.

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“…The high biomass and diversity attained by such tropical vegetation patches contrasts with the coastal landscape, dominated by the mangrove and deciduous forest communities. The amount of organic matter in shallow coastal ecosystems is a controlling factor of the microbial reduction of nitrate, or denitrification, and further loss to the atmosphere or transfer to other metabolic pathways within the system (Boynton et al, 1995). Thus, the overall low nitrate concentrations observed across the lagoon in rainfalls may …”

mentioning

confidence: 99%

Seasonal Responses of Phyloplankton Productivity to Water-Quality Variations in a Coastal Karst Ecosystem of the Yucatan Peninsula

Medina-Gómez

Herrera-Silveira

2009

goms

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Inputs, Transformations, and Transport of Nitrogen and Phosphorus in Chesapeake Bay and Selected Tributaries

Cited by 525 publications

References 46 publications

Effects of land-use change on nutrient discharges from the Patuxent River watershed

Effects of land-use change on nutrient discharges from the Patuxent River watershed

Quantifying watershed‐scale groundwater loading and in‐stream fate of nitrate using high‐frequency water quality data

Seasonal Responses of Phyloplankton Productivity to Water-Quality Variations in a Coastal Karst Ecosystem of the Yucatan Peninsula

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