Spatial analysis of blue carbon in a UK Saltmarsh: Implications of carbon distribution.

In recent years saltmarshes have been found to be significant stores of blue carbon with important links to the global carbon cycle. Saltmarshes have the ability to sequester a significant amount of carbon with long residence times once buried. In this investigation, the spatial distribution of organic carbon of surficial sediments and the factors driving its production and preservation were studied at Biggar Saltmarsh, situated on Walney Island, west of Barrow-in-Furness on the north side of Morecambe Bay, England. Thirty-three sediment samples were collected from the surface (0-3cm depth) layer of the marsh along a linear transect extending from the highest marsh to the seawards limit of vegetation. Random spatial sampling was undertaken to ensure different marsh sub-environments were effectively sampled. Precise elevation data was collected for all sediment samples. Laboratory tests of samples included; TOC, TN, LOI, pH, conductivity and grain size analysis. Three silt-dominated marsh zones were defined with an upper high marsh comprising Phragmites australis (Zone 1), a mid-marsh area (Zone 2) with vegetation including Triglochin maritima, Puccinellia sp., and a low marsh area (Zone 3) characterised by Spartina alterniflora. Organic matter, carbon and nitrogen decreased from high to low marsh. The highest values were in high marsh/elevations (TOC: 26.6 + 7.84%, Organic matter: 49 + 14.49%, TN: 1.9 + 0.55%) and the lowest values found within low marsh/ elevations (TOC: 3.5 + 7.84%, Organic matter: 8 + 14.49%, TN: 0.35 + 0.55%). Organic carbon, organic matter and nitrogen were found to have a significant relationship to elevation; r= 0.931, p<0.05; r=0.834, p<0.05; r=0.942, p<0.05 respectively, indicating that elevation, controlled by tidal inundation and subsequently establishment of less salt tolerant vegetation, is one of the main controls of organic carbon burial. No correlations were established between organic geochemical results and grain size indicating the latter parameter is not a major driver of carbon preservation at Biggar. High C/N ratios were found with highest in the high marsh (16.85) decreasing seaward (11.85), C/N values indicate a high influence of terrestrial vegetation input of organic matter. Based on sea-level rise data it has been estimated that 67% of carbon will be lost from Biggar Saltmarsh with a sea-level rise of 7.1mm/yr. The high amounts of organic carbon found within Biggar Saltmarsh highlights the importance of these blue carbon environments and the need to protect them in relation to future sea-level rise and anthropogenic impacts.

Name dc:type.qualificationname

mphil

Level dc:type.qualificationlevel

masters

Grantor dc:publisher.institution

Liverpool John Moores University

Year dc:date.issued

2019

Author dc:creator

• Baugh, L

Contributors dc:contributor

• Kirby, J
• Kiriakoulakis, K

• GE Environmental Sciences
• QD Chemistry

DOI dc:identifier.doi

https://doi.org/10.24377/LJMU.t.00010878

OAI identifier oai:identifier

oai:researchonline.ljmu.ac.uk:10878