Background: Early diagenetic processes involved in natural organic matter (NOM) oxidation in marine sediments have been for the most part characterized after collecting sediment cores and extracting porewaters. These techniques have proven useful for deep-sea sediments where biogeochemical processes are limited to aerobic respiration, denitrification, and manganese reduction and span over sever...

Microorganisms have contributed significantly to subsurface energy resources by converting organic matter in hydrocarbon reservoirs into methane, the main component of natural gas. In this study, we consider environmental controls on microbial populations in coal-bearing strata of the Cherokee basin, an unconventional natural gas resource in southeast Kansas, USA. Pennsylvanian-age strata in th...

Macrofossil analysis of a composite 19 m long sediment core from Rano Raraku Lake (Easter Island) was related to litho-sedimentary and geochemical features of the sediment. Strong stratigraphical patterns are shown by indirect gradient analyses of the data. The good correspondence between the stratigraphical patterns derived from macrofossil (Correspondence Analysis) and sedimentary and geochem...

Detailed knowledge of environmental conditions is required to understand faunal production in coastal seas with topographic and hydrographic complexity. We test the hypothesis that organic biomass and production of subtidal sediment invertebrates throughout the Strait of Georgia, west coast of Canada, can be predicted by depth, substrate type and organic flux modified to reflect lability and ag...

Most of the dissolved iron (Fe) in seawater is complexed by organic ligands. One key issue in understanding Fe limitation in the sea is the bioavailability of different forms of Fe to marine phytoplankton. We measured Fe uptake by the coastal diatom Thalassiosira pseudonana and the cyanobacterium Synechococcus sp., using model ligands desferrioxamine B (DFB) and ferrichrome (FC), humic acids (H...

An integrated multidisciplinary study utilizing geochemical and microbial ecological approaches was conducted to characterize the origins, chemical nature, and quantities of dissolved and particulate organic matter (OM) utilized by heterotrophic bacteria in a temperate estuary. C : N, stable isotope (d13C), and lipid biomarker analyses revealed differences in the inferred reactivity of autochth...

The effect of a metal mixture (Cu, Zn, Pb, and Ni) on Cd fractionation in sediment and its accumulation by the freshwater macrophyte Eriocaùlon septangulàre was examined in an in situ experiment in the littoral zone at the Experimental Lakes Area, northwestern Ontario, Canada. Fresh sediment was spiked with Cd alone and together with the metal mixture at three concentration levels. Macrophytes ...

Humans have had a significant impact on the terrestrial pedosphere through activities such as agriculture and urbanization. The effects of human activities on land use and the related environmental changes were investigated through point and areal studies surrounding Meiliang Bay, which is an open area of extreme eutrophication in Taihu Lake, China. This study used remote sensing and environmen...

PHT3D, a three-dimensional, MODFLOW/MT3DMS-based reactive multicomponent transport model is presented. The model couples, via an operator-splitting method, the transport simulator MT3DMS (Zheng and Wang, 1998) and the geochemical package PHREEQC-2 (Parkhurst and Appelo, 1999). Through the flexible, generic nature of PHREEQC-2, PHT3D can handle a broad range of equilibrium and kinetic reactive p...

Temporal variation in geochemistry can cause changes in microbial community structure and diversity. Here we studied temporal changes of microbial communities in Tengchong hot springs of Yunnan Province, China in response to geochemical variations by using microbial and geochemical data collected in January, June and August of 2011. Greater temporal variations were observed in individual taxa t...