Palustrine

Palustrine – Outputs

 

The conceptual models were compiled by researchers in collaboration with a wide range of stakeholders from Natural Resource Management groups, universities and government agencies and based on available scientific information[4].

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The outputs of nitrogen (N) from a palustrine wetland are dependent on the concentrations of N that enter the wetland, the nature of the palustrine wetland (condition, connection, size etc.), the form of nitrogen (i.e. ammonium (NH₄), nitrate (NO₃), dissolved organic nitrogen (DON) or particulate nitrogen (PN)), the carbon and N stocks within the wetland, and the rates of processes occurring inside the wetlands (e.g. denitrification, sedimentation, and plant uptake). 

Air

The denitrification process can account for about 64-70% of nitrogen removal to air from palustrine wetland water and soils[1].

Export of nitrogen as N₂O is likely to occur as a result of incomplete denitrification and nitrification. Less than 1% of denitrified N is converted to N₂O[2]. 

Ammonia release is minor, except in highly polluted and anoxic waterways.

Water

Surface water and groundwater

Overall N loads exported from palustrine wetlands will be lower than inputs received by wetlands due to the transformations to the air (denitrification), and storage in soils and biota (stocks). During the dry season, outputs of nitrogen from palustrine wetlands are more likely through groundwater flows. In the wet season, large and sporadic pulses of floodwater will transport large amounts of water, and with it, dissolved (93 (41-142) g/ha/day^* as NH₄) and particulate N[3]. Outputs from groundwater and floodwater are likely to be lower than inputs for dissolved inorganic N (NH₄, NO₃), and might be higher for dissolved organic N (DON), depending on the productivity of the wetland and the intensity of internal processes (e.g. denitrification, sedimentation, and plant uptake)[7]. Dissolved organic N exports (DON) are also likely to occur in area with highly labile vegetation (e.g. grasses), especially if it is senescent, or if it undergoes drying and rewetting[6].

Vegetated litter

Litter comprising leaves, twigs and bark is exported during the wet season at a rate of 9.8 (0-50) g/ha/day^*. Litter fall export tends to be seasonal, with increased leaf litter in the dry season, and increased litter export during large floods[3]. The amount of litter as N exported from a wetland is associated with its productivity.

Biota

Localised and temporary populations of birds can remove a significant amount of nitrogen from a wetland, particularly in breeding events[4][5].

Macrophytes can be flushed out of the lakes during flooding events, when most of the biomass can be exported during strong rainfall events.

Anthropogenic

Harvesting of trees, reeds, and fish, or removal of weeds can remove nitrogen from wetlands.

^*_{Nitrogen quantities are displayed as an average followed by a minimum and maximum (range), e.g. “average (min. of range - max. of range) units”.}

References

1. ^ Adame, MF, Reef, R, Wong, VNL, Balcombe, SR, Turschwell, MP, Kavehei, E, Rodríguez, DC, Kelleway, JJ, Masque, P & Ronan, M (2020), 'Carbon and nitrogen sequestration of Melaleuca floodplain wetlands in tropical Australia', Ecosystems. [online], vol. doi.org/10. Available at: https://link.springer.com/article/10.1007%2Fs10021-019-00414-5.
2. ^ Beaulieu, JJ, Tank, JL, Hamilton, SK, Wollheim, WM, Hall, RO, Mulholland, PJ, Peterson, BJ, Ashkenas, LR, Cooper, LW, Dahm, CN, Dodds, WK, Grimm, NB, Johnson, SL, McDowell, WH, Poole, GC, Valett, HM, Arango, CP, Bernot, MJ, Burgin, AJ, Crenshaw, CL, Helton, AM, Johnson, LT, O'Brien, JM, Potter, JD, Sheibley, RW, Sobota, DJ & Thomas, SM (2011), 'Nitrous oxide emission from denitrification in stream and river networks', Proceedings of the National Academy of Sciences. [online], vol. 108, no. 1, pp. 214-219. Available at: http://www.pnas.org/cgi/doi/10.1073/pnas.1011464108.
3. ^ a b Finlayson, CM, Cowie, ID & Bailey, BJ (1993), 'Biomass and litter dynamics in a Melaleuca forest on a seasonally inundated floodplain in tropical, northern Australia', Wetlands Ecology and Management, vol. 2, no. 4, pp. 177-188.
4. ^ Jaensch, R (1999), The status and importance of Queensland's south-western wetlands. [online] Available at: http://www.southwestnrm.org.au/ihub/status-importance-southwest-queenslands-wetlands.
5. ^ Jardine, TD, Pusey, BJ, Hamilton, SK, Pettit, NE, Davies, PM, Douglas, MM, Sinnamon, V, Halliday, IA & Bunn, SE (2012), 'Fish mediate high food web connectivity in the lower reaches of a tropical floodplain river', Oecologia, vol. 168, pp. 829-838.
6. ^ Lu, J, Bunn, SE & Burford, MA (May 2018), 'Nutrient release and uptake by littoral macrophytes during water level fluctuations', Science of The Total Environment. [online], vol. 622-623, pp. 29-40. Available at: https://linkinghub.elsevier.com/retrieve/pii/S0048969717332576 [Accessed 2 November 2020].
7. ^ Morrisey K.M., FTR (1988), 'Regeneration and uptake of ammonium by plankton in an Amazon floodplain lake.', J Plankton Res, no. 10, pp. 31-48.

Last updated: 31 July 2021