Atmospheric deposition of nutrients to the North Atlantic Basin

Prospero, Joseph M.; Barrett, Kevin; Church, Thomas M.; Dentener, Frank; Duce, Robert A.; Galloway, James N.; Levy, H.; Moody, J. L.; Quinn, Patricia K.

doi:10.1007/978-94-009-1776-7_2

Cited by 121 publications

(121 citation statements)

References 108 publications

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“…Further, only wet deposition is measured at the NADP stations, and challenges remain in how to estimate contributions from dry deposition, given the complexity of factors controlling deposition velocities (Ollinger et al 1993, Meyers et al 2001). The estimate used in Howarth et al (1996) comes from the GCTM model, which predicts depositional patterns globally at a relatively course spatial scale using emission sources as inputs and modeling atmospheric transformations and transport (Prospero et al 1996). A similar, more recent model (TM3) used by Galloway et al (2004) for their global and regional nitrogen budgets yields a comparable estimate for the northeastern U.S. as did the GCTM model.…”

Section: Resultsmentioning

confidence: 98%

The influence of climate on average nitrogen export from large watersheds in the Northeastern United States

et al. 2006

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The flux of nitrogen in large rivers in North America and Europe is well explained as a function of the net anthropogenic inputs of nitrogen to the landscape, with on average 20 to 25% of these inputs exported in rivers and 75 to 80% of the nitrogen retained or denitrified in the landscape. Here, we use data for average riverine nitrogen fluxes and anthropogenic inputs of nitrogen over a 6-year period (1988)(1989)(1990)(1991)(1992)(1993) for 16 major watersheds in the northeastern United States to examine if there is also a climatic influence on nitrogen fluxes in rivers. Previous studies have shown that for any given river, nitrogen fluxes are greater in years with higher discharge, but this can be interpreted as storage of nitrogen in the landscape during dry years and flushing of this stored nitrogen during wet years. Our analyses demonstrate that there is also a longer-term steady-state influence of climate on riverine nitrogen fluxes. Those watersheds that have higher precipitation and higher discharge export a greater fraction of the net anthropogenic inputs of nitrogen. This fractional export ranges from 10 to 15% of the nitrogen inputs in drier watersheds in the northeastern United States to over 35% in the wetter watersheds. We believe this is driven by lower rates of denitrification in the wetter watersheds, perhaps because shorter water residence times do not allow for as much denitrification in riparian wetlands and low-order streams. Using mean projections for the consequences of future climate change on precipitation and discharge, we estimate that nitrogen fluxes in the Susquehanna River to Chesapeake Bay may increase by 3 to 17% by 2030 and by 16 to 65% by 2095 due to greater fractional delivery of net anthropogenic nitrogen inputs as precipitation and discharge increase. Although these projections are highly uncertain, they suggest a need to better consider the influence of climate on riverine nitrogen fluxes as part of management efforts to control coastal nitrogen pollution.

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Section: Resultsmentioning

confidence: 98%

The influence of climate on average nitrogen export from large watersheds in the Northeastern United States

et al. 2006

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“…comm.). This model has been widely used and validated extensively for N species (e.g., Dentener and Crutzen 1994;Prospero et al 1996;Holland et al 1999). We used TM3 model simulations for 1860, 1990, and 2050.…”

Section: Appendix II the Ntni Model Of Riverine Nr Transportmentioning

confidence: 99%

Nitrogen Cycles: Past, Present, and Future

et al. 2004

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This paper contrasts the natural and anthropogenic controls on the conversion of unreactive N 2 to more reactive forms of nitrogen (Nr). A variety of data sets are used to construct global N budgets for 1860 and the early 1990s and to make projections for the global N budget in 2050. Regional N budgets for Asia, North America, and other major regions for the early 1990s, as well as the marine N budget, are presented to highlight the dominant fluxes of nitrogen in each region. Important findings are that human activities increasingly dominate the N budget at the global and at most regional scales, the terrestrial and open ocean N budgets are essentially disconnected, and the fixed forms of N are accumulating in most environmental reservoirs. The largest uncertainties in our understanding of the N budget at most scales are the rates of natural biological nitrogen fixation, the amount of Nr storage in most environmental reservoirs, and the production rates of N 2 by denitrification.

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“…Over the last five years, the wet input of N to the site was on average 2.7 kg N ha )1 year )1 . Howarth et al (1996) estimated NO y (ensemble of NO x and its reservoirs, such as HNO 3 and N 2 O 5 ) and NH x (NH 3 þ NH þ 4 ) deposition for the Caribbean by applying estimates of N wet+dry deposition to the North Atlantic region modeled by Propero et al (1996). They estimated that, in the Caribbean, modern NO y is deposited at a rate of 2.1 kg N ha )1 year )1 (wet+dry).…”

Section: Atmospheric Nitrogen Depositionmentioning

confidence: 99%

Urban influences on the nitrogen cycle in Puerto Rico

et al. 2006

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Anthropogenic actions are altering fluxes of nitrogen (N) in the biosphere at unprecedented rates. Efforts to study these impacts have concentrated in the Northern hemisphere, where experimental data are available. In tropical developing countries, however, experimental studies are lacking. This paper summarizes available data and assesses the impacts of human activities on N fluxes in Puerto Rico, a densely populated Caribbean island that has experienced drastic landscape transformations over the last century associated with rapid socioeconomic changes. N yield calculations conducted in several watersheds of different anthropogenic influences revealed that disturbed watersheds export more N per unit area than undisturbed forested watersheds. Export of N from urban watersheds ranged from 4.8 kg ha )1 year )1 in the Rı´o Bayamo´n watershed to 32.9 kg ha )1 year )1 in the highly urbanized Rı´o Piedras watershed and 33.3 kg ha )1 year )1 in the rural-agricultural Rı´o Grande de An˜asco watershed. Along with land use, mean annual runoff explained most of the variance in fluvial N yield. Wastewater generated in the San Juan Metropolitan Area receives primary treatment before it is discharged into the Atlantic Ocean. These discharges are N-rich and export large amounts of N to the ocean at a rate of about 140 kg ha )1 year )1 . Data on wet deposition of inorganic N (NH þ 4 þ NO À 3 ) suggest that rates of atmospheric N deposition are increasing in the pristine forests of Puerto Rico. Stationary and mobile sources of NO x (NO+NO 2 ) and N 2 O generated in the large urban centers may be responsible for this trend. Comprehensive measurements are required in Puerto Rico to quantitatively characterize the local N cycle. More research is required to assess rates of atmospheric N deposition, N fixation in natural and human-dominated landscapes, N-balance associated with food and feed trade, and denitrification.

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Atmospheric deposition of nutrients to the North Atlantic Basin

Cited by 121 publications

References 108 publications

The influence of climate on average nitrogen export from large watersheds in the Northeastern United States

The influence of climate on average nitrogen export from large watersheds in the Northeastern United States

Nitrogen Cycles: Past, Present, and Future

Urban influences on the nitrogen cycle in Puerto Rico

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