Sources of nitrogen to estuaries in the United States

Castro, Mark S.; Driscoll, Charles T.; Jordan, Thomas E.; Reay, William G.; Boynton, Walter R.

doi:10.1007/bf02711991

Cited by 90 publications

(53 citation statements)

References 12 publications

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“…Oligotrophy defines the aquatic landscape of ENP-Most estuaries and many freshwater bodies show some degree of cultural eutrophication today, and trajectories of change in these systems are often toward increased human influence on biogeochemical cycles (Castro et al 2003). Oligotrophic systems may provide valuable end-member references for cross-system eutrophication studies, such as the synthesis objective of this special issue.…”

Section: Discussionmentioning

confidence: 99%

“…Effects tend to accumulate along hydrologic flow gradients, from primary streams, through large rivers and reservoirs, and ultimately to estuaries. Perhaps for this reason, freshwater ecosystems should be more likely to be oligotrophic than estuaries; most estuaries and coastal ecosystems are currently experiencing some degree of cultural eutrophication (Howarth et al 2000;Castro et al 2003). Oligotrophic freshwater systems are particularly vulnerable to even low levels of nutrient addition, and Vounatsou and Karydis (1991) suggested the use of oligotrophic aquatic systems as reference sites in eutrophication studies.…”

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confidence: 99%

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Relating precipitation and water management to nutrient concentrations in the oligotrophic “upside‐down” estuaries of the Florida Everglades

Childers

Boyer

Davis

et al. 2006

Limnology & Oceanography

165

142

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We present 8 yr of long-term water quality, climatological, and water management data for 17 locations in Everglades National Park, Florida. Total phosphorus (P) concentration data from freshwater sites (typically Ͻ0.25 mol L Ϫ1 , or 8 g L Ϫ1 ) indicate the oligotrophic, P-limited nature of this large freshwater-estuarine landscape. Total P concentrations at estuarine sites near the Gulf of Mexico (average ഠ0.5 mol L Ϫ1 ) demonstrate the marine source for this limiting nutrient. This ''upside down'' phenomenon, with the limiting nutrient supplied by the ocean and not the land, is a defining characteristic of the Everglade landscape. We present a conceptual model of how the seasonality of precipitation and the management of canal water inputs control the marine P supply, and we hypothesize that seasonal variability in water residence time controls water quality through internal biogeochemical processing. Low freshwater inflows during the dry season increase estuarine residence times, enabling local processes to control nutrient availability and water quality. El Niño-Southern Oscillation (ENSO) events tend to mute the seasonality of rainfall without altering total annual precipitation inputs. The Niño3 ENSO index (which indicates an ENSO event when positive and a La Niña event when negative) was positively correlated with both annual rainfall and the ratio of dry season to wet season precipitation. This ENSO-driven disruption in seasonal rainfall patterns affected salinity patterns and tended to reduce marine inputs of P to Everglades estuaries. ENSO events also decreased dry season residence times, reducing the importance of estuarine nutrient processing. The combination of variable water management activities and interannual differences in precipitation patterns has a strong influence on nutrient and salinity patterns in Everglades estuaries.Nutrient enrichment and cultural eutrophication affect virtually all aquatic systems to some degree (Carpenter et al.

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Relating precipitation and water management to nutrient concentrations in the oligotrophic “upside‐down” estuaries of the Florida Everglades

Childers

Boyer

Davis

et al. 2006

Limnology & Oceanography

165

142

View full text Add to dashboard Cite

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“…Agricultural activities, urban development, and fossil fuel combustion have increased nitrogen (N) loading to coastal ecosystems (Valiela et al 1997, Howarth et al 2002, Castro et al 2003, Fitch et al 2009), adversely affecting human and ecosystem health (Vitousek et al 1997, Bowen and Valiela 2001, Galloway et al 2003, Townsend et al 2003. Salt marshes occupy the transition zone between marine and terrestrial ecosystems, and can retain or remove a large proportion of upslope N inputs that would otherwise enter the ocean (Seitzinger 1988, Nixon et al 1996, Brin et al 2010.…”

Section: Introductionmentioning

confidence: 99%

Microbially mediated nitrogen retention and loss in a salt marsh soil

2015

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Abstract. Salt marshes currently play an important role as filters for upslope nitrogen (N) inputs. This could change in the future with sea level rise, warming and eutrophication, which are expected to favor monocultures over diverse plant communities. We explored patterns in gross N cycling, dissimilatory nitrate (NO 3 À ) reduction to ammonium (NH 4 þ ) (DNRA), and denitrification in a salt marsh soil under two typical redox conditions (aerobic and anaerobic), and in soils under plant communities manipulated to simulate potential future composition (forb and graminoid monocultures). Natural salt marsh soils exhibited high potential gross N mineralization rates, averaging 50.4 6 5.7 lg N g À1 d À1 under aerobic conditions; rates declined to 23.6 6 3.4 lg N g À1 d À1 under an N 2 headspace. Microbial NH 4 þ uptake and gross nitrification together accounted for only 14 % of gross N mineralization. Nitrogen retention via DNRA and microbial uptake greatly exceeded N losses via denitrification. Gross nitrification rates were greater in the forb and graminoid monocultures than in the control. This effect may be mediated by the lower plant biomass in the monocultures than in the control, which may have reduced competition between plants and nitrifiers for NH 4 þ . Soil NO 3 À concentrations and net nitrous oxide (N 2 O) fluxes were greatest for the forb monoculture, likely due to higher soil oxygen (O 2 ) concentrations in these plots. Our results suggest that salt marsh soils with a diverse plant community have high potential rates of N mineralization and microbial N retention, and the establishment of forb monocultures could lead to greater ecosystem N losses.

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“…We assumed that the standard deviation for each of deposition rates in eq 6 was equal to the estimate of the loading rate and that the standard deviation for the export coefficient in eq 6 was equal to the estimate of the export coefficient. These assumptions were not unreasonable based on the RMSE values given in Tables 3 and 4 for wet N deposition rates, comparisons of predicted dry S deposition rates for 15 watersheds reported by Mitchell et al (2011), and the range of watershed N export rates across 43 watersheds studied by Castro et al (2003). Uncertainties on land and water areas were assumed to be $0, and areas and the unit conversion were multiplied through eq 6 such that units on deposition rates were metric tons N yr À1 .…”

Section: Uncertainty In Atmospheric N Loading Ratesmentioning

confidence: 99%

Application of watershed deposition tool to estimate from CMAQ simulations the atmospheric deposition of nitrogen to Tampa Bay and its watershed

Poor

Pribble²,

Schwede

2012

Journal of the Air & Waste Management Association

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The U.S. Environmental Protection Agency (EPA) has developed the Watershed Deposition Tool (WDT) to calculate from the Community Multiscale Air Quality (CMAQ) model output the nitrogen, sulfur, and mercury deposition rates to watersheds and their sub-basins. The CMAQ model simulates from first principles the transport, transformation, and removal of atmospheric pollutants. We applied WDT to estimate the atmospheric deposition of reactive nitrogen (N) to Tampa Bay and its watershed. Implications: Air quality modeling reveals that atmospheric deposition of reactive nitrogen (N) contributes a significant fraction to Tampa Bay's total N loading from external sources. Regulatory drivers that lower nitrogen oxide emissions from power plants and motor vehicles are important to bay management strategies, which seek to improve water quality through N load reduction.

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Sources of nitrogen to estuaries in the United States

Cited by 90 publications

References 12 publications

Relating precipitation and water management to nutrient concentrations in the oligotrophic “upside‐down” estuaries of the Florida Everglades

Relating precipitation and water management to nutrient concentrations in the oligotrophic “upside‐down” estuaries of the Florida Everglades

Microbially mediated nitrogen retention and loss in a salt marsh soil

Application of watershed deposition tool to estimate from CMAQ simulations the atmospheric deposition of nitrogen to Tampa Bay and its watershed

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