Sources of nitrogen in three watersheds of northern Florida, USA: Mainly atmospheric deposition

Journal Article · Tue Mar 01 00:00:00 EST 1994 · Geochimica et Cosmochimica Acta; (United States)

DOI:https://doi.org/10.1016/0016-7037(94)90560-6· OSTI ID:7286022

Fu, Ji-Meng; Winchester, J W ^[1]

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1. Florida State Univ., Tallahassee, FL (United States)

Atmospheric deposition is estimated to be the principal source of N in water that flows to the Apalachicola river from the Chattahoochee and Flint Rivers (ACF) as well as in two nearby small rivers, Ochlockonee (Och) and Sopchoppy (Sop), that drain watersheds with different land use characteristics. By mass balance and descriptive statistics of hundreds of rainfall and river water samples from monitoring programs since the 1960s, the average nitrate and ammonium deposition flux from the atmosphere is sufficient to account for N that flows toward Apalachicola Bay, an estuary in which N may be a limiting nutrient. Urban and agricultural sources of N in the three watersheds ACF, Och, and Sop appear to be relatively smaller. The work was based on long-term data bases from the National Atmospheric Deposition Program (NADP) rain chemistry monitoring network and the U.S. Geological Survey (USGS) water monitoring program. Average atmospheric N depositions to the three river watersheds are nearly the same as river fluxes of N in all forms monitored. Nitrogen is not likely to be a limiting nutrient in the three watersheds, since river water N:P exceeds the Redfield ratio. An estimate of largest possible input of urban sewage is several times lower than the atmospheric flux of N to the ACF watershed. And N from N-fertilizer, comparable to the atmospheric deposition flux of N, is likely to be smaller if mostly retained in crops or farmland before it reaches the estuary. Annual nitrogen export from the Apalachicola River to the estuary, 1.22 x 10[sup 9] moles N yr[sup [minus]1], consists of organic nitrogen 60%, nitrate 34%, and NH[sup +][sub 4]6%. Atmospheric nitrate and sulfate depositions are highly correlated, both being principally from fossil fuel combustion. Hydrologic conditions, which exhibit variations on seasonal and longer time scales, play an important role in the transport of nutrients and other species in the rivers.

• OSTI ID: 7286022
• Journal Information: Geochimica et Cosmochimica Acta; (United States), Vol. 58:6; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
NITROGEN
DEPOSITION
ORIGIN
SURFACE WATERS
CHEMICAL COMPOSITION
ACID RAIN
AIR POLLUTION
AMMONIUM COMPOUNDS
FOSSIL FUELS
ORGANIC NITROGEN COMPOUNDS
ATMOSPHERIC PRECIPITATIONS
ELEMENTS
ENERGY SOURCES
FUELS
NONMETALS
ORGANIC COMPOUNDS
POLLUTION
RAIN
540320* - Environment
Aquatic- Chemicals Monitoring & Transport- (1990-)