Carbon isotopes and iodine concentrations in a Mississippi River delta core recording land use, sediment transport, and dam building in the river's drainage basin.

摘要: Abstract Sedimentary material from coastal and nearshore areas in the Mississippi Delta region are comprised of different organic carbon sources with diverse ages that require isotopic elemental records for resolving various plant residues. Carbon (13C, 14C) values were used to differentiate contributions plants using C3, C4, and/or CAM (crassulacean acid metabolism) fixation pathways., iodine concentrations indicated wetland residues a significant source sediment core River delta collected at 60 m water depth. This had been extensively described Oktay et al. [Oktay, S.D., Santschi, P.H., Moran, J.E., Sharma, P., 2000. The 129Iodine Bomb Pulse Recorded Sediments: Results Isotopes I, Pu, Cs, Pb, C. Geochim. Cosmochim. Acta 64 (6), 989–996.] significantly, includes unique features not previously seen marine environment. These special include plutonium close-in fallout record indicates purely terrestrial these particles elements associated it, distinct peak (as well as peaks cesium isotopes) indicate little bioturbation this core. Our data can thus be compared published changes drainage basin land use, river hydrology, hydrodynamic sorting suspended elucidate if reflected sediments. comparison suggests contribution (OC) C4 sediments during 1950’s early 1960’s. Relative older isotopes, episodically high (up 34 ppm) observed time period (1) deposition is coincident times major hydrological induced dam levee building both upper lower reaches basin, (2) suggest episodic