TITLE:
Remediation of Coastal Sediments by Addition of Calcium Nitrate and Presence of Benthos in a Muddy Tidal Flat
AUTHORS:
Hiroyuki Harada, Kotarou Akagi, Hiroaki Tutioka, Atushi Hashimoto
KEYWORDS:
Redox Potential, Muddy Tidal Sediment, Denitrification, Bioturbation, Calcium Nitrate
JOURNAL NAME:
Journal of Environmental Protection,
Vol.5 No.8,
June
16,
2014
ABSTRACT: This
study investigated the change in denitrification rate in muddy tidal flats sediment by chemical and
biological remediation. Column experiments were conducted to determine the
dependence of denitrification rate on the redox potential. Filtered seawater
was fed continuously to the pipe filled with sediment from the muddy tidal
flats. An increase in the redox potential from -198 mV to 21 mV with
bioturbation led to increases in the denitrification rate from 24.2 mg/m2/day
to 29.8 mg/m2/day. The increase in denitrification was explained by
the acceleration of mass transfer in the sediment. Redox-potential increased from -400
mV to -200 mV by the addition of 10 g calcium nitrate, acid volatile sulfide
was below the detection limit to 20 cm depth, and denitrification rate was
increased from 21.3 mg/m2/day to 36.4 mg/m2/day. It is
considered that the increased nitrogen concentration led to an increase in
microbial activity.