Dissolved organic nitrogen: a dynamic participant in aquatic ecosystems

Breaks in the cycle: dissolved organic nitrogen in terrestrial ecosystems

Dissolved organic nitrogen (DON) is present in soils and streams around the world. We are only now beginning to explore the important roles this chemically heterogeneous mixture of compounds plays in terrestrial nitrogen (N) cycling. Over centuries, DON leaching may represent a significant "leak" of N, which occurs because plants and microbes cannot prevent DON losses, even in times of high N d...

Molecular exploration of bioavailable dissolved organic matter across aquatic ecosystems

Mangrove tannins in aquatic ecosystems: Their fate and possible influence on dissolved organic carbon and nitrogen cycling

We describe the fate of mangrove leaf tannins in aquatic ecosystems and their possible influence on dissolved organic nitrogen (DON) cycling. Tannins were extracted and purified from senescent yellow leaves of the red mangrove (Rhizophora mangle) and used for a series of model experiments to investigate their physical and chemical reactivity in natural environments. Physical processes investiga...

Dissolved organic nitrogen budgets for upland, forested ecosystems in New England

Relatively high deposition of nitrogen (N) in the northeastern United States has caused concern because sites could become N saturated. In the past, mass-balance studies have been used to monitor the N status of sites and to investigate the impact of increased N deposition. Typically, these efforts have focused on dissolved inorganic forms of N (DIN = NH4-N + NO3-N) and have largely ignored dis...

Dissolved organic nitrogen uptake by seagrasses

We examined the ability of seagrasses to take up dissolved organic nitrogen (DON) with leaves (in situ) and roots (laboratory) in an oligotrophic tropical offshore meadow in Indonesia using 15N-labeled nitrogen (N) substrates. We compared the uptake of urea and amino acids with that of ammonium (NH z4 ) and nitrate (NO { 3 ) and determined uptake kinetics of amino acids for the seagrasses Thala...