The first report of Glomalin from the Sundarban Mangrove Biosphere Reserve, India, a long-term sediment Carbon storage

Abstract

Seasonal and vertical profile of Glomalin Related Soil Protein (GRSP) from Arbuscular mycorrhizal fungi showed an explanatory outcome related to the carbon sequestration processes in the sediment of the Sundarban Mangrove biosphere reserve. A decreasing trend was found for total GRSP (T-GRSP) and easily extractable GRSP (EE-GRSP) with increase in depth whereas a reverse profile was found for difficulty extractable GRSP (DE-GRSP) in the deep forest region. Accumulation of Glomalin during post-monsoon found to be 1.43 times and 1.41 times higher than that of pre-monsoon and monsoon season, respectively. A significant impact of soil redox potential on the accumulation of difficulty extractable GRSP (DE-GRSP) indicated possible acceleration in Glomalin synthesis and subsequent carbon sequestration under enhanced sediment anoxicity in this biosphere reserve. Sediment salinity, temperature and pH did not show any significant cause on the occurrence of Glomalin related soil proteins, indicating its limited dependence on these environmental parameters. A direct correlation was perceptible between the number of arbuscular mycorrhizal fungal spores with T-GRSP, EE-GRSP and DE-GRSP in the sediment during the study period from 2012 to 2014. Organic carbon showed a strong positive correlation with Glomalin related soil protein T-GRSP (mg g−1 dry wt of sediment) = 3.06 Organic Carbon (%)+ 0.13; R2=0.95], indicating a significant fraction of organic carbon is converted to GRSP as long-term carbon storage by Arbuscular Mycorrhizal Fungi present in the sediment of this unique biosphere reserve.