The seasonal variation and depth distribution of the capacity for denitrification and dissimilatory NO(3) reduction to NH(4) (NO(3) ammonification) were studied in the upper 4 cm of the sediment of Norsminde Fjord estuary, Denmark. A combination of C(2)H(2) inhibition and N isotope techniques was used in intact sediment cores in short-term incubations (maximum, 4 h). The denitrification capacit...

The biomass of sediment organisms can be measured by a.llowing carbon tracer to distribute itself through sediment cores. Application of this method to sediment from Marion lake, British Columbia, indicated that most of the sediment microorganisms were concentrated in the top 2 cm of sediment, where the total biomass of microorganisms was estimated to be 183IJ.g C/cm2• The radiotracer estimate ...

Sediment cores from the Colorado River (CR) remnant delta were used to assess the changing sedimentation and pollutant deposition processes in response to extensive human manipulation of the river. The cores are formed of alternating layers of clays and silts, with isolated sandy horizons. The clayey units are interpreted as periods of flood flows into this low gradient and meandering estuary a...

APPROACH In July-August 1998 aboard the USNS Bowditch, we collected sediment cores, CTDs and XBTs, 3.5 kHz subbottom profiles, and high-resolution 48-channel seismic profiles. This survey covered as much of the Gulf as possible given the restrictions that reefs, oil fields and territorial limits have on ship operations. The approach was to seismically map Neogene stratigraphy and tie this struc...

Baihua Reservoir in Guizhou Province, China, experienced serious Hg contamination from Guizhou Organic Chemical Plant (GOCP) between 1971 and 1997. However, the biogeochemical cycling of Hg in this reservoir is not well studied. Sediment cores were collected in fall 2002, spring 2003 and in spring and fall 2004. THg and MeHg concentrations in all sediment profiles ranged from 0.26 to 38.9 mg/kg...

The Gironde fluvial estuarine system is impacted by historic metal pollution (e.g. Cd, Zn, Hg) and oysters (Crassostrea gigas) from the estuary mouth have shown extremely high Cd concentrations for decades. Based on recent work (Chiffoleau et al., 2005) revealing anomalously high Ag concentrations (up to 65 mg kg(-1); dry weight) in Gironde oysters, we compared long-term (~1955-2001) records of...

High resolution geochemical (Itrax micro-XRF and wavelength dispersive XRF) data, radiochronology (Pb and Cs analyses) and ultra-high precision double-spike lead isotope measurements from lacustrine sediment cores are used in combination with historical research of former mining landscapes to investigate modern pollution signals in sediments from Windermere, the largest lake in the English Lake...

Geochemical measurements on well-dated sediment cores from Lake Er (Erhai) are used to determine the timing of changes in metal concentrations over 4500 years in Yunnan, a borderland region in southwestern China noted for rich mineral deposits but with inadequately documented metallurgical history. Our findings add new insight into the impacts and environmental legacy of human exploitation of m...

The aim of the study was to determine whether using chemical and radiochemical analysis of lake sediments can highlight changes in the climate. Also it was studied whether human impact on the environment can be observed and to what extent such changes are in agreement with historical data. Samples of 16 cm thick sediment cores from the Smreczynski Staw Lake were collected and divided into 1 cm ...