A Py–GC–MS and NMR spectroscopy study of organic nitrogen in Mangrove Lake sediments

Solid-state CP–MAS 13C and 15N nuclear magnetic resonance (NMR) spectroscopy and flash pyrolysis–gas chromatography–mass spectrometry (Py-GC–MS) techniques have been used to characterize the organic-rich sedimentary deposit from Mangrove Lake, Bermuda. The chemical nature of organic nitrogen in sediment samples from different depths was studied as it relates to the early diagenesis of proteinaceous material in the reducing marine environment. Although the majority of proteins were lost during early diagenesis, part of the proteinaceous material became resistant to proteolysis and chemical hydrolysis. The proteinaceous material is proposed to have survived early diagenesis via encapsulation by refractory, aliphatic organic matter.