Anaerobic diagenesis of silica and carbon in continental margin sediments: Discrete zones of TCO2 production

Details Anaerobic diagenesis of silica and carbon in continental margin sediments: Discrete zones of TCO2 production Anaerobic diagenesis of silica and carbon in continental margin sediments: Discrete zones of TCO2 production

Oct 2005

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2005gecoa..69.4611b&link_type=abstract

Geochimica et Cosmochimica Acta, Volume 69, Issue 19, p. 4611-4629.

Physics

6

Scientific paper

Pore water profiles of dissolved Si, Ca2+, SO42-, CH4, and TCO2 (Dissolved Inorganic Carbon; DIC) were determined from multicores and gravity cores collected at nine sites off Southern California, the west coast of Mexico, and within the Gulf of California. These sites were located within the eastern North Pacific oxygen minimum zone at depths of 400 to 900 m and in settings where bottom water oxygen concentrations were <3 μM and sediments were laminated. Pore water profiles were defined at a resolution of millimeters (whole core squeezing), centimeters (sectioning and squeezing) and meters (gravity core sectioning and squeezing), and diffusive fluxes were calculated for different zones within the sediment column. The flux of dissolved silica across the sediment-water interface (SWI) ranged from 0.3 to 3.4 mmol Si m-2d-1, and TCO2 fluxes ranged from 0.8 to 4.6 mmol C m-2d-1. A positive correlation (r = 0.74) existed between these fluxes, yet these two constituents exhibited significantly different diagenetic behavior downcore; dissolved Si generally reached a constant concentration (between 450 and 900 μM) in the upper few cm, whereas TCO2 concentrations increased monotonically with depth. Methane was detected at micromolar levels in sediment intervals between 0 and 60 cm and at five sites, increased to millimolar levels at depths of 80 to 170 cm. At the horizon marking the appearance of millimolar levels of methane, there was a distinct change in slope of the sulfate and TCO2 gradients. A flux budget for this horizon was determined by using linear fits to pore water profiles; these budgets indicate that the upward TCO2 flux away from this horizon is 40 to 50% greater than the downward sulfate flux to this horizon. Given that the TCO2 flux to this horizon from below was quite small, this imbalance suggests that anaerobic oxidation of methane by sulfate is not the only process producing TCO2 within this horizon. A budget for TCO2 at this horizon is balanced when 40 to 80% of the sulfate flux is attributed to organic carbon remineralization. Of the DIC that diffuses across the SWI, 20 to 40% is generated by reactions occurring within or below this deep reaction horizon.

Affiliated with

Also associated with

No associations

Rating

Anaerobic diagenesis of silica and carbon in continental margin sediments: Discrete zones of TCO2 production does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Anaerobic diagenesis of silica and carbon in continental margin sediments: Discrete zones of TCO2 production, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Anaerobic diagenesis of silica and carbon in continental margin sediments: Discrete zones of TCO2 production will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1625287