Drained coastal peatlands: A potential nitrogen source to marine ecosystems under prolonged drought and heavy storm events-A microcosm experiment.

Wang, Hongjun

Richardson, Curtis J

Ho, Mengchi

Flanagan, Neal

Netherlands

2017-11-01T14:02:30Z

2017-11-01T14:02:30Z

2016-10-01

Over the past several decades there has been a massive increase in coastal eutrophication, which is often caused by increased runoff input of nitrogen from landscape alterations. Peatlands, covering 3% of land area, have stored about 12-21% of global soil organic nitrogen (12-20Pg N) around rivers, lakes and coasts over millennia and are now often drained and farmed. Their huge nitrogen pools may be released by intensified climate driven hydrologic events-prolonged droughts followed by heavy storms-and later transported to marine ecosystems. In this study, we collected peat monoliths from drained, natural, and restored coastal peatlands in the Southeastern U.S., and conducted a microcosm experiment simulating coupled prolonged-drought and storm events to (1) test whether storms could trigger a pulse of nitrogen export from drought-stressed peatlands and (2) assess how differentially hydrologic managements through shifting plant communities affect nitrogen export by combining an experiment of nitrogen release from litter. During the drought phase, we observed a significant temporal variation in net nitrogen mineralization rate (NMR). NMR spiked in the third month and then decreased rapidly. This pattern indicates that drought duration significantly affects nitrogen mineralization in peat. NMR in the drained site reached up to 490±110kgha(-1)year(-1), about 5 times higher than in the restored site. After the 14-month drought phase, we simulated a heavy storm by bringing peat monoliths to saturation. In the discharge waters, concentrations of total dissolved nitrogen in the monoliths from the drained site (72.7±16.3mgL(-1)) was about ten times as high as from the restored site. Our results indicate that previously drained peatlands under prolonged drought are a potent source of nitrogen export. Moreover, drought-induced plant community shifts to herbaceous plants substantially raise nitrogen release with lasting effects by altering litter quality in peatlands.

https://www.ncbi.nlm.nih.gov/pubmed/27236627

S0048-9697(16)30957-3

1879-1026

https://hdl.handle.net/10161/15701

eng

Elsevier BV

Sci Total Environ

10.1016/j.scitotenv.2016.04.211

Drought

Eutrophication

Nitrogen mineralization

Peatlands

Plant community

Storm

Drained coastal peatlands: A potential nitrogen source to marine ecosystems under prolonged drought and heavy storm events-A microcosm experiment.

Journal article

Wang, Hongjun|0000-0002-2105-2745

Ho, Mengchi|0000-0001-6876-9666

https://www.ncbi.nlm.nih.gov/pubmed/27236627

621

626

Duke

Environmental Sciences and Policy

Marine Science and Conservation

Nicholas School of the Environment

Published

566-567