Eutrophication Model for the Patuxent Estuary: Advances in Predictive Capabilities

Lung, Wu‐Seng; Nice, Alex J.

doi:10.1061/(asce)0733-9372(2007)133:9(917)

Cited by 27 publications

(32 citation statements)

References 12 publications

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“…Further research is needed to identify specific mechanisms underlying this trend in the Patuxent and how similar effects could occur in other estuaries. Simulation modeling studies could be used to test hypotheses about alternative mechanisms (Lung and Nice 2007), including the effects of variations in Susquehanna flow, climate-induced shifts in estuarine circulation, and changes in Chesapeake Bay's lateral seiching events (e.g., Malone et al 1986). …”

Section: Regional Differences In Water Quality Responsesmentioning

confidence: 99%

Long-Term Changes in Water Quality and Productivity in the Patuxent River Estuary: 1985 to 2003

Testa

Kemp

Boynton

et al. 2008

Estuaries and Coasts

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We conducted a quantitative assessment of estuarine ecosystem responses to reduced phosphorus and nitrogen loading from sewage treatment facilities and to variability in freshwater flow and nonpoint nutrient inputs to the Patuxent River estuary. We analyzed a 19-year dataset of water quality conditions, nutrient loading, and climatic forcing for three estuarine regions and also computed monthly rates of net production of dissolved O 2 and physical transport of dissolved inorganic nitrogen (DIN) and phosphorus (DIP) using a salt-and waterbalance model. Point-source loading of DIN and DIP to the estuary declined by 40-60% following upgrades to sewage treatment plants and correlated with parallel decreases in DIN and DIP concentrations throughout the Patuxent. Reduced point-source nutrient loading and concentration resulted in declines in phytoplankton chlorophyll-a (chl-a) and light-saturated carbon fixation, as well as in bottomlayer O 2 consumption for upper regions of the estuary. Despite significant reductions in seaward N transport from the middle to lower estuary, chl-a, turbidity, and surfacelayer net O 2 production increased in the lower estuary, especially during summer. This degradation of water quality in the lower estuary appears to be linked to a trend of increasing net inputs of DIN into the estuary from Chesapeake Bay and to above-average river flow during the mid-1990s. In addition, increased abundance of Mnemiopsis leidyi significantly reduced copepod abundance during summer from 1990 to 2002, which favored increases in chla and allowed a shift in total N partitioning from DIN to particulate organic nitrogen. These analyses illustrate (1) the value of long-term monitoring data, (2) the need for regional scale nutrient management that includes integrated estuarine systems, and (3) the potential water quality impacts of altered coastal food webs.

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Section: Regional Differences In Water Quality Responsesmentioning

confidence: 99%

Long-Term Changes in Water Quality and Productivity in the Patuxent River Estuary: 1985 to 2003

Testa

Kemp

Boynton

et al. 2008

Estuaries and Coasts

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“…The water quality model we used is the 2-dimensional (longitudinal−vertical) CE-QUAL-W2 model initially developed by the United States Army Corps of Engineers (Cole & Wells 2000) and subsequently modified by Lung & Bai (2003) and Lung & Nice (2007) to model water quality in the Patuxent River. The water quality model divides the river into 163 longitudinal segments at the surface, each with a length of 613 m. Each river segment is then divided into 1 m depth intervals for a total of 1993 spatial cells.…”

Section: Water Quality Modelmentioning

confidence: 99%

“…Inter-annual variability in rainfall affects the magnitude of nutrient loadings and river flows in the Patuxent River , Lung & Nice 2007. Variability in the magnitude of nutrient loadings affects the extent and intensity of hypoxia, while variability in river flows affects the degree of stratification.…”

Section: Introductionmentioning

confidence: 99%

“…High water flow during wet years can amplify the effects of increased nutrient loadings on hypoxia by reducing the mixing between the oxygenated surface layer and the hypoxic bottom layer. Water quality modeling has shown that stratification and nutrient loads would increase in the Patuxent River during wet years , Lung & Bai 2003, Lung & Nice 2007, leading to an earlier onset of hypoxia and a larger volume of hypoxic water compared to dry years (Hagy et al 2004).…”

Section: Introductionmentioning

confidence: 99%

“…Patuxent River water quality and the physical structure of the water column are both affected by changes in nutrient loading rates from the Patuxent River watershed, Chesapeake Bay water quality at the downstream boundary, and inter-annual variability in rainfall , Lung & Bai 2003, Fisher et al 2006, Lung & Nice 2007. Land use in the Patuxent River watershed has changed dramatically over the past 150 yr, from primarily agricultural (~85% agriculture and 15% forested) in the 1850s to a mix of forested (51.6%), agriculture (28.5%), residential (15.5%), and urban (4.3%) in 1994 (D'Elia et al 2003).…”

Section: Introductionmentioning

confidence: 99%

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Simulating the effect of hypoxia on bay anchovy egg and larval mortality using coupled watershed, water quality, and individual-based predation models

Adamack

Rose²,

Breitburg³

et al. 2012

Mar. Ecol. Prog. Ser.

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Greater nutrient loads since the 1950s have increased the extent and duration of hypoxic conditions in the Patuxent River and the Chesapeake Bay (Maryland, USA). We linked watershed, water quality, and individual-based predation models to predict how changes in local (Patuxent River watershed) and regional (bay-wide) nutrient loading rates would affect bay anchovy Anchoa mitchilli egg and larval mortality rates in the lower region of the Patuxent River. Nutrient loadings affected hypoxic volume and the degree of spatial overlap between anchovy and their predators. Mortality rates were simulated during June and July under combinations of a wet or dry year, reduced and increased nutrient loadings from the Patuxent River watershed, and increased and decreased nutrient loadings into the Patuxent River at the Chesapeake Bay boundary. Chesapeake Bay water quality at the downstream boundary had a much larger effect on egg and larval mortality rates than nutrient loading rates from the Patuxent River watershed, and these responses were consistent with the downstream boundary condition having a greater effect on hypoxia. Water column structure, year type (wet/dry), and location within the lower Patuxent River had smaller effects on egg and larval mortality. Due to indirect effects, the effect of the Chesapeake Bay boundary condition on larval mortality rates during June was opposite to that predicted for egg mortality rates. Our results illustrate that statements and justifications about the benefits of nutrient loading reductions on estuarine ecosystems should avoid oversimplification, be specific, and recognize that species responses to changes in environmental conditions can be complex and variable.

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Density‐driven water circulation in a typical tributary of the Three Gorges Reservoir, China

Long

Yang

et al. 2019

River Research & Apps

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A 2-D hydrodynamic model was developed for modelling water circulation from 2008 to 2011 in a typical tributary of the Three Gorges Reservoir. The model is capable of describing flow behaviour and mixing mechanisms for different density current patterns and performs well in computing the velocity, the intrusion layer at the plunge point, and the travel distance of the density current. The effects of 10 flow patterns on thermal stratification, hydrodynamics, and algal bloom risk are discussed and classified in terms of algal growth. Patterns (6) and (10) can effectively prevent algal blooms; Patterns (7) and (8) are good for algal blooms. More frequent transformations of flow-driven patterns, as observed in 2010-2011, could create more eddies and mixing and thus reduce bloom risk. Further studies are necessary and recommended for more accurate predictions, assessing the impact of water level fluctuations on transform flow patterns and water quality.

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Eutrophication Model for the Patuxent Estuary: Advances in Predictive Capabilities

Cited by 27 publications

References 12 publications

Long-Term Changes in Water Quality and Productivity in the Patuxent River Estuary: 1985 to 2003

Long-Term Changes in Water Quality and Productivity in the Patuxent River Estuary: 1985 to 2003

Simulating the effect of hypoxia on bay anchovy egg and larval mortality using coupled watershed, water quality, and individual-based predation models

Density‐driven water circulation in a typical tributary of the Three Gorges Reservoir, China

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