@article { ISI:000481723500018,
	title = {The application of delta C-13, TOC and C/N geochemistry of mangrove sediments to reconstruct Holocene paleoenvironments and relative sea levels, Puerto Rico},
	journal = {MARINE GEOLOGY},
	volume = {415},
	year = {2019},
	month = {SEP},
	pages = {105963},
	abstract = {We assessed the use of delta C-13, TOC and C/N values of bulk sedimentary organic matter (OM) to reconstruct paleoenvironmental and relative sea-level change from mangrove environments in Puerto Rico. The modern distribution of delta C-13, TOC and C/N values was described from 63 vegetation and 59 surface sediment samples collected from three sites containing basin and riverine mangrove stands, and was compared to microfossil (foraminiferal and thecamoebian) assemblages. Four vertically-zoned environments were identified: tidal flat (delta C-13: -18.6 +/- 2.8 parts per thousand; TOC: 10.2 +/- 5.7\%; C/N: 12.7 +/- 3.1), mangrove (delta C-13: -26.4 +/- 1.0 parts per thousand; TOC: 33.9 +/- 13.4\%; C/N: 24.3 +/- 6.2), brackish transition (delta C-13: -28.8 +/- 0.7 parts per thousand; TOC: 40.8 +/- 11.7\%; C/N: 21.7 +/- 3.7), and freshwater swamp (delta C-13: -28.4 +/- 0.4 parts per thousand; TOC: 42.8 +/- 4.8\%; C/N: 17.0 +/- 1.1). These environments had distinct delta C-13, TOC and C/N values, with the exception of the brackish transition and freshwater swamp zones that were difficult to distinguish on a geochemical basis alone. The foraminiferal assemblages were complicated by a group that did not show a relationship to elevation due to the presence of calcareous foraminifera occurring above mean higher high water (MHHW), likely resulting from washover or transport by storms. However, the ratio of foraminifera to thecamoebians (F/T) along with delta C-13, TOC and C/N values refines the distinction between brackish and freshwater environments. Using linear discriminant analysis, we applied the delta C-13, TOC, C/N and F/T distributions to a 1.7 m core containing a continuous sequence of Rhizophora mangle peat, which began accumulating at similar to 1650-1930 CE. Together, microfossils, delta C-13, TOC, and C/N values, and the core chronology from Cs-137 and radiocarbon dating revealed that sediments in the core likely accumulated in response to anthropogenic sediment delivery, making it unsuitable for relative sea-level reconstruction. We caution that in the absence of detailed litho-, bio-, chemo-, or chrono-stratigraphic analyses as presented here, care should be taken in interpreting sea-level histories derived from single dates on mangrove peats.},
	issn = {0025-3227},
	doi = {10.1016/j.margeo.2019.105963},
	author = {Khan, Nicole S. and Vane, Christopher H. and Engelhart, Simon E. and Kendrick, Chris and Horton, Benjamin P.}
}
