Regional nitrogen budgets and riverine N &amp; P fluxes for the drainages to the North Atlantic Ocean: Natural and human influences

Howarth, Robert W.; Billen, Gilles; Swaney, Dennis P.; Townsend, Andrea K.; Jaworski, Norbert A.; Lajtha, Kate; Downing, John A.; Elmgren, Ragnar; Caraco, Nina F.; Jordan, Teresa E.; Berendse, F.; Freney, J. R.; Kudeyarov, V. N.; Murdoch, Peter S.; Zhu, Zhao-Liang Z.-L.

doi:10.1007/978-94-009-1776-7_3

Cited by 622 publications

(705 citation statements)

References 113 publications

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“…Marine phytoplankton in temperate regions tend to be N-limited and suffer increasingly from cultural eutrophication as a result of N addition (Howarth et al 1996). In contrast, phosphorus (P) supply limits primary productivity of most freshwater systems (Dillon and Rigler 1974).…”

Section: Introductionmentioning

confidence: 99%

Hydrological and biological processes modulate carbon, nitrogen and phosphorus flux from the St. Lawrence River to its estuary (Quebec, Canada)

et al. 2017

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Increased flux of carbon and nutrients from human activities in river basins were linked to acidification and deepwater hypoxia in estuaries and coastal areas worldwide. Annual loads (1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011) of suspended particulate matter (SPM), dissolved organic carbon (DOC), total nitrogen (TN) and total phosphorus (TP) were assessed at the Lake Ontario inlet of the St. Lawrence River (SLR) (7110 m 3 s -1 ) and its estuarine outlet at Québec City (12,090 m 3 s -1 ). Internal loads from the Ottawa River (1950 m 3 s -1 ), seventeen other tributaries, urban wastewaters, atmospheric deposition and erosion were also estimated. Erosion (65% of SPM, 29% of TP), inflow from Lake Ontario (42% of DOC, 47% of TN) and Ottawa River (28% of DOC) contributed important flux to the estuary. Loads from other tributaries (20 and 27% of TN and TP at Quebec City) largely exceeded municipal sources (6% of exported TN and TP) and require future remediation. Aquatic plants fixed 277,000 t of C, 49,000 t of N and 7000 t of P (May-Sept.), delaying the nutrient flux to the estuary and turning the SLR into a nutrient sink over summers of lowest discharge. Degradation of exported organic C could consume 5.4-7.1 million t O 2 year -1 in the estuary whereas SLR flux of N and P represent 31-47% and 7-14% of total annual estuarine flux, respectively. Carbon and Nitrogen flux from freshwaters partly explain the decline in pH and oxygen concentrations in deep estuarine waters thus highlighting the need to reduce diffuse sources of nutrients in the entire watershed.

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Section: Introductionmentioning

confidence: 99%

Hydrological and biological processes modulate carbon, nitrogen and phosphorus flux from the St. Lawrence River to its estuary (Quebec, Canada)

et al. 2017

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“…Most of this anthropogenic combined nitrogen is used as fertilizer for human food production and much is unintentionally widely distributed by uncontrolled hydrologic and atmospheric transport (Howarth et al, 1996). In humid climates a considerable fraction of the N surplus from fields and meadows ends up in rivers.…”

Section: Introductionmentioning

confidence: 99%

Source identification of nitrate by means of isotopic tracers in the Baltic Sea catchments

et al. 2006

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Abstract. Nitrate input to a river is largely controlled by land use in its catchment. We compared the information carried by the isotopic signatures of nitrate in 12 Baltic rivers, in relation to the vegetation cover, land use, and fertilization of agricultural land of their catchments. We found isotope values in nitrate ranging from −2 to 14‰ for δ 15 N and 8 to 25‰ for δ 18 O. The annual variability of riverine nitrate isotope signatures is presented in detail for one Nordic, the Kemijoki, and two southern rivers, the Vistula and Oder. Nordic rivers with relatively pristine vegetation in their catchments show not only low δ 15 N values and high δ 18 O-NO − 3 but also lower annual variability than rivers draining densely populated land. Seasonal signals were found in all the rivers. We used load weighted nitrate isotope data and data from the three major N sources (farmland/sewage, atmospheric deposition and from runoff of pristine soils) to theoretically estimate the shares of nitrate from these sources. The results of an isotope mixing model (IMM-1) agree reasonably well with the same estimates for agricultural land derived from a Global Land Cover (GLC) data base, with a deviation varying from −16% to +26%. The comparison with an emission model (EM) reveals relatively good agreements for intensively used catchments (−18 to +18% deviation). Rather unsatisfactory agreement was found between the IMM-1 and GLC calculations for pristine catchments (−36 to +50% deviation). Advantages and limitations of the tested model are discussed.

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“…Denitrification is the reduction process of nitrate to nitric oxide, nitrous oxide and nitrogen gas by microorganism, which should be initiated first by nitrification [3].…”

Section: Denitrificationmentioning

confidence: 99%

“…Many of the heterotrophic bacteria in biological wastewater treatment systems are capable of using either dissolved oxygen or nitrate-nitrogen as terminl electron acceptor [17]. In denitrification process, the electron donor is typically one of three sources: (a) the soluble substrate in the influent wastewater, (b) the soluble substrate produced during endogenous decay, and (c) an exogenous source such as methanol or acetate [3]. These three sources are considered as the carbon source for the bacteria.…”

Section: Denitrificationmentioning

confidence: 99%

“…There is increased recognition by environmental protection professionals on the adverse impacts that can be caused by incessant discharge of nutrients, especially nitrogen and phosphorus into the aquatic environment (Howarth et al [3]). Improved prominence on the control for nutrients has resulted in the development of emerging wastewater innovations, which include biological nutrient removal (BNR) processes.…”

Section: Introductionmentioning

confidence: 99%

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Potential of the compact extended aeration reactor (CEAR) as an integrated system to biologically degrade municipal sewage according to Malaysian regulatory limits: design, process and performance

Kutty¹,

Isa²,

Audu³

et al. 2014

Energy and Sustainability V

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A laboratory scale integrated biological reactor was designed and fabricated to perform organic removal, nitrification and denitrification from synthetic sewage with the C:N:P ratio 100:10:2. The configuration of the reactor is anoxic -aeration and anoxic with a settler, integrated within one system. A suspended growth medium guarantees adequate organic and nutrient removal, in a continuous flow stirred chamber reactor (CFSTR). The arrangement resembles the Bardenpho process, which combines Wuhrmann's and modified Ludzak-Ettinger processes. The purpose is innovation to provide a minimal footprint to make the system modular, user friendly, with easy operation and maintenance compared with conventional methods. Similarly, the aim is to attain the Department of Environment (DOE) Malaysia revised Environment Quality Regulation Act 2009 (EQA, 1974) review on ammonia, nitrate and phosphorus discharge limits by reducing negative impacts due to discharge into receiving water bodies. Effluent ammonia and nitrate limits were set at a minimum of 5 mg/L and 10 mg/L, respectively. The removal of phosphorus was inadequate because phosphorus requires an anaerobic process. The reduction of biochemical oxygen demand (BOD5), chemical oxygen demand (COD), ammonia-nitrogen (NH4-N), nitratenitrogen (NO3-N), total phosphorus (TP) and total suspended solids (TSS) were achieved at 92.8%, 89.5%, 81%, 66%, 23% and 92.5%, respectively. The removal of ammonia and nitrate-nitrogen were enhanced within the last phase at 90.2% and 80% reduction, respectively.

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Regional nitrogen budgets and riverine N & P fluxes for the drainages to the North Atlantic Ocean: Natural and human influences

Cited by 622 publications

References 113 publications

Hydrological and biological processes modulate carbon, nitrogen and phosphorus flux from the St. Lawrence River to its estuary (Quebec, Canada)

Hydrological and biological processes modulate carbon, nitrogen and phosphorus flux from the St. Lawrence River to its estuary (Quebec, Canada)

Source identification of nitrate by means of isotopic tracers in the Baltic Sea catchments

Potential of the compact extended aeration reactor (CEAR) as an integrated system to biologically degrade municipal sewage according to Malaysian regulatory limits: design, process and performance

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