Carbon isotopically based estimates of CO2 levels have been generated from a record of the photosynthetic fractionation of •3C (-%) in a central equatorial Pacific sediment core that spans the last ~255 ka.

Heavy metal concentrations and magnetic susceptibility of sediment samples were analyzed as indicators of urban and industrial contamination in Anzali wetland in Gilan, Iran. The aim was to investigate the suitability of magnetic properties measurements for indicating heavy metal pollution. The concentration of six heavy metals (Ni, Cr, Cd, Zn, Fe, and Pb) was determined in different depths of ...

Pulses of fine sediment in gravel-bedded rivers can cause extensive fine sediment infiltration (FSI) into void spaces in coarse bed material, potentially altering river morphodynamics and aquatic ecosystems. Previous work suggests a conceptual model of FSI whereby FSI occurs to a limited depth as a function of the relative grain size of bed sediment compared with infiltrating sediment and is in...

Arsenic (As) fractions in the sediments of seven lakes from East Plain Ecoregion and six lakes from Yungui Plateau Ecoregion, China, were investigated. Results indicated that the total As concentrations in sediment samples of lakes of the East Plain Lake Ecoregion are higher than those of Yungui Plateau Lake Ecoregion. Residual As is the main fraction in sediment samples of lakes from both ecor...

Mercury (Hg) contamination is pervasive in aquatic ecosystems and its bioaccumulation may lead to severe health concerns for both wildlife and humans. In this study we quantify historical Hg fluxes to the profundal sediment of Seneca Lake, NY. Previous studies show that the highest surface sediment Hg concentrations occur here, near a major tributary, the Keuka Lake Outlet. This tributary hoste...

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 and elemental records for resolving the various sources of plant residues. Carbon isotopic ((13)C, (14)C) values were used to differentiate contributions from plants using the C3, C4, and/or CAM (crassulacean acid metabol...

A multi-proxy approach was used to examine the geomorphic dynamics and environmental history of an upper deltaic floodplain tract in the Sacramento-San Joaquin Delta, California. Three long cores were collected from the McCormack-Williamson Tract (MWT) and these cores were analyzed for bulk density, loss-on-ignition, fine (clay and silt) content, Al concentration, magnetic susceptibility, polle...

Prokaryote communities in post-glacial profundal freshwater sediments of Windermere, representing 10-12,000 years of deposition, were examined for culturability, viability and community structure. The potential for active geochemical cycles was inferred from the presence of specific groups of bacteria. Direct count procedures revealed 10(12) cells (g dry wt sediment)-1 in the surface sediments,...

Diffuse reflectance spectra measured during shipboard core description with a hand-held Minolta spectrophotometer are reliable data for interpreting sediment composition. Factor analysis of these spectra indicates that only Glad Cling Wrap, a polyethylene food wrap, should be used to cover wet cores during measurement because it introduces substantially less noise into the spectra than other b...

HydroTrend, a climate-driven hydrologic transport model, is used to simulate the suspended sediment discharge of the Waipaoa River System (WRS) over the last 5.5 kyr. We constrain the precipitation input with a paleo-rainfall index derived from the high-resolution Lake Tutira storm sediment record. The simulation is extended to 22 ka using a lower resolution version of the model, constrained by...