@article {2804,
	title = {How Could a Freshwater Swamp Produce a Chemical Signature Characteristic of a Saltmarsh?How Could a Freshwater Swamp Produce a Chemical Signature Characteristic of a Saltmarsh?},
	journal = {ACS Earth and Space Chemistry},
	volume = {2},
	year = {2018},
	month = {Jun-01-2019},
	pages = {9 - 20},
	abstract = {Reduction{\textendash}oxidation (redox) reaction conditions, which are of great importance for the soil chemistry of coastal marshes, can be temporally dynamic. We present a transect of cores from northwest Florida wherein radical postdepositional changes in the redox regime has created atypical geochemical profiles at the bottom of the sedimentary column. The stratigraphy is consistent along the transect, consisting of, from the bottom upward, carbonate bedrock, a gray clay, an organic mud section, a dense clay layer, and an upper organic mud unit representing the current saltwater marsh. However, the geochemical signature of the lower organic mud unit suggests pervasive redox reactions, although the interval has been identified as representing a freshwater marsh, an unlikely environment for such conditions. Analyses indicate that this discrepancy results from postdepositional diagenesis driven by millennial-scale environmental parameters. Rising sea level that led to the deposition of the capping clay layer, created anaerobic conditions in the freshwater swamp interval, and isolated it hydrologically from the rest of the sediment column. The subsequent infiltration of marine water into this organic material led to sulfate reduction, the buildup of H2S and FeS, and anoxic conditions. Continued sulfidation eventually resulted in euxinic conditions, as evidenced by elevated levels of Fe, S, and especially Mo, the diagnostic marker of euxinia. Because this chemical transformation occurred long after the original deposition the geochemical signature does not reflect soil chemistry at the time of deposition and cannot be used to infer syn-depositional environmental conditions, emphasizing the importance of recognizing diagenetic processes in paleoenvironmental studies.},
	keywords = {anoxic, diagenesis, euxinic, florida, Molybdenum, reactions, redox, XRF},
	issn = {2472-3452},
	doi = {10.1021/acsearthspacechem.7b00098},
	url = {https://pubs.acs.org/doi/10.1021/acsearthspacechem.7b00098},
	author = {McCloskey, Terrence A. and Smith, Christopher G. and Liu, Kam-biu and Marot, Marci and Haller, Christian}
}
@article { ISI:000268272100013,
	title = {Fish scales in sediments from off Callao, central Peru},
	journal = {DEEP-SEA RESEARCH PART II-TOPICAL STUDIES IN OCEANOGRAPHY},
	volume = {56},
	number = {{16}},
	year = {2009},
	month = {JUL 15},
	pages = {1113-1124},
	type = {Article},
	abstract = {We study fish scales as a proxy of fish abundance and preservation biases together with phosphorus from fish remains (P(fish)) in a sediment core retrieved off Callao, Peru (12 degrees 1{\textquoteright}S, 77 degrees 42{\textquoteright}W; water depth = 179 m; core length = 52 cm). We interpret our results as a function of changing redox conditions based on ratios of redox-sensitive trace elements (Cu/Al, Mo/Al, Ni/Al, Zn/Al, V/Al), terrigenous indicators (Fe in clays, Ti, Al), and biogenic proxies (CaCO(3), biogenic opal, total nitrogen, organic carbon, barite Ba). The core covers roughly 700 years of deposition, based on (210)Pb activities extrapolated downcore and (14)C dating at selected intervals. Our fish-scale record is dominated by anchovy (Engraulis ringens) scales followed by hake (Merluccius gayii) scales. The core presented an abrupt lithological change at 17 cm (corresponding to the early 19th century). Above that depth, it was laminated and was more organic-rich (10-15\% organic carbon) than below, where the core was partly laminated and less organic-rich (< 10\%). The lithological shift coincides with abrupt changes in dry bulk density and in the contents of terrigenous and redox-sensitive trace elements, biogenic proxies, and fish scales. The remarkable increase in redox-sensitive trace elements in the upper 17 cm of the core suggests more reducing conditions when compared with deeper and older horizons, and is interpreted as an intensification of the oxygen minimum zone off Peru beginning in the early 19th century. Higher fish-scale contents and higher P(fish)/P(total) ratios were also observed within the upper 17 cm of the core. The behavior of biogenic proxies and redox-sensitive trace elements was similar; more reduced conditions corresponded to higher contents of CaCO(3), C(org), total nitrogen and fish scales, suggesting that these proxies might convey an important preservation signal. (C) 2008 Elsevier Ltd. All rights reserved.},
	keywords = {Callao, Clupeoid fish, Molybdenum, Oxygen minimum zone, Peru, Redox-sensitive trace elements},
	issn = {0967-0645},
	doi = {10.1016/j.dsr2.2008.09.015},
	author = {Diaz-Ochoa, J. A. and Lange, C. B. and Pantoja, S. and De lange, G. J. and Gutierrez, D. and Munoz, P. and Salamanca, M.}
}
