SS2.02 Biogeochemical Process at the Sediment-Water Interfaces
Date: Tuesday, June 11, 2002
Time: 2:30:00 PM
Location: Carson B
 
LaursenAE, Rutgers, The State University of New Jersey, New Brunswick, NJ, USA, laursen.1@nd.edu
Seitzinger, S, P, Rutgers, The State University of New Jersey, New Brunswick, NJ, USA, sybil@imcs.rutgers.edu
 
ESTIMATING BIOGEOCHEMICAL PROCESSES IN RIVERS AT THE WHOLE-REACH SCALE A MODELING APPROACH BUILT ON HIGH PRECISION MEASUREMENT OF DISSOLVED GASES.
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Obtaining realistic estimates of biogeochemical transformations in ecosystems is often constrained by methodological limitations. We have developed a method for estimating rates of biogeochemical processes that produce or consume gases. The method is based on high-precision measurement of dissolved gases using membrane inlet mass spectrometry and modeling atmospheric exchange using volatile, non-reactive tracers. This approach allows us to measure production / consumption of various gases at the whole-reach scale. Thus, we can begin testing hypotheses about these processes in a meaningful context. We are using this approach to estimate in situ rates of denitrification, and net oxygen, nitrous oxide, and methane production / consumption in three small rivers, two in agricultural watersheds and one in a suburban watershed. The results of ongoing studies suggest denitrification can remove a significant amount of nitrogen during riverine transport. The total amount of nitrogen removed appears to be greatest during the spring-flush, however the efficiency of nitrogen removal is greater during base flow. The results also suggest that small rivers could be an important source of the greenhouse gas nitrous oxide.