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Salt marshes' capacity to sink carbon may be threatened by nitrogen pollution

Date:
August 26, 2019
Source:
Marine Biological Laboratory
Summary:
Salt marshes sequester carbon at rates an order of magnitude higher than land ecosystems. A new study indicates nitrate pollution of coastal waters stimulates the decomposition of organic matter in salt marsh sediments that normally would have remained stable, and can alter the capacity of salt marshes to sequester carbon over the long term.
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Deep in the waterlogged peat of salt marshes, carbon is stored at much greater rates than in land ecosystems, serving as an offset to climate change due to carbon dioxide (CO2) build-up in the atmosphere.

However, a new study indicates that a common pollutant of coastal waters, nitrate, stimulates the decomposition of organic matter in salt marsh sediments that normally would have remained stable over long periods of time. This increase in decomposition, which releases CO2, could alter the capacity of salt marshes to sequester carbon over the long term. The study, led by scientists at the Marine Biological Laboratory (MBL), Woods Hole, and Northeastern University, is published in Global Change Biology.

"Traditionally, we have viewed salt marshes as resilient to nitrogen pollution, because the microbes there remove much of the nitrogen as gas through a process called denitrification," writes first author Ashley Bulseco, a postdoctoral scientist at the MBL.

"But this research suggests that when nitrate is abundant, a change occurs in the microbial community in salt marsh sediments that increases the microbes' capacity to degrade organic matter. This potentially reduces the ability of the marsh to store carbon," Bulseco writes.

As global temperatures continue to rise, a number of carbon capture strategies have been proposed, including sequestering CO2 in "blue carbon" habitats such as salt marshes, mangroves and seagrass meadows. However, coastal nitrogen pollution is also still rising in many areas due to agricultural and urban runoff, and sewage.

"Given the extent of nitrogen loading along our coastlines, it is imperative that we better understand the resilience of salt marsh systems to nitrate, especially if we hope to rely on salt marshes and other blue carbon systems for long-term carbon storage," the authors write.

The next phase of this research, already in progress, is to analyze the microbial community responsible for degrading carbon in a salt marsh ecosystems, especially when exposed to high concentrations of nitrate.


Story Source:

Materials provided by Marine Biological Laboratory. Note: Content may be edited for style and length.


Journal Reference:

  1. Ashley N. Bulseco, Anne E. Giblin, Jane Tucker, Anna E. Murphy, Jonathan Sanderman, Kenly Hiller‐Bittrolff, Jennifer L. Bowen. Nitrate addition stimulates microbial decomposition of organic matter in salt marsh sediments. Global Change Biology, 2019; DOI: 10.1111/gcb.14726

Cite This Page:

Marine Biological Laboratory. "Salt marshes' capacity to sink carbon may be threatened by nitrogen pollution." ScienceDaily. ScienceDaily, 26 August 2019. <www.sciencedaily.com/releases/2019/08/190826092340.htm>.
Marine Biological Laboratory. (2019, August 26). Salt marshes' capacity to sink carbon may be threatened by nitrogen pollution. ScienceDaily. Retrieved October 31, 2024 from www.sciencedaily.com/releases/2019/08/190826092340.htm
Marine Biological Laboratory. "Salt marshes' capacity to sink carbon may be threatened by nitrogen pollution." ScienceDaily. www.sciencedaily.com/releases/2019/08/190826092340.htm (accessed October 31, 2024).

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