Tidal effects on the organic carbon mineralization rate under aerobic conditions in sediments of an intertidal estuary

Abstract

Laboratory experiments and field measurements were conducted to examine the effect of tide on the organic carbon mineralization rate in sediments under aerobic conditions of an intertidal estuary. Core samples of surface sediments were collected from an intertidal estuary of the Kurose River, Hiroshima, Japan. To mimic low and high tide in the intertidal estuary, organic carbon mineralization rates in the samples were measured in the laboratory under both air-exposed and submerged conditions. Mineralization rates under air-exposed conditions were two to five times higher than those under submerged conditions. Field measurements of the rate of CO 2 emission from the sediment surface revealed a rapid increase in the rate as the sea level fell during ebb tide. The estimated amount of daily organic carbon mineralization assuming a constantly submerged condition was 30% less than that estimated when considering the semi-diurnal fluctuation in sea level. These results indicate that tide has a marked impact on the organic carbon mineralization rate in sediments under aerobic conditions on an intertidal estuary, and tidal effects need to be considered when the amount of mineralized organic carbon is estimated.

Annual sediment respiration in estuarine sandy intertidal flats in the Seto Inland Sea, Japan

“…The effect of the tide on the sediment respiration rates was also considered in the model because a previous study reported that the tide affected the respiration rates, and the rate under air-exposed conditions was higher than the rate under submerged conditions (Sasaki et al 2009). …”

“…where R E(T) is the sediment respiration rate (mg CO 2 -C m -2 h -1 ) under air-exposed conditions at sediment temperature T (°C); R S(T 0 ) is the sediment respiration rate (mg CO 2 -C m -2 h -1 ) under submerged conditions at sediment temperature T 0 (°C); R E(30) is 38.8 mg CO 2 -C m -2 h -1 (mean of in situ sediment respiration rates at a sediment temperature 30°C); R S(30) is 16.9 mg CO 2 -C m -2 h -1 (based on a value for R E(T) /R S(T) of 2.3; Sasaki et al 2009); t is the duration of submerged conditions per day (h); and Q 10 is 1.8 (this study; Fig. 3).…”

“…We examined CO 2 emission rates from the sediment surface during low tide at each of the 10 stations with a portable infrared gas analyzer (Li-6400, Li-Cor, NE, USA). The measurements were conducted following the procedure described in our previous study, after the lowest sea level when the CO 2 emission rate becomes constant (Sasaki et al 2009). Replicate measurements (n = 8), which took a total of at least 20 min, were conducted at each station.…”

Effects of semi-lunar tidal cycling on soil CO2 and CH4 emissions: a case study in the Yangtze River estuary, China

“…However, the temporal variations in CO 2 and CH 4 effluxes were positively correlated with change in the water table in the littoral zone of Lake Obuchi, Japan (Yamamoto et al 2009(Yamamoto et al , 2011. Also, CO 2 emission was reported to be greatly inhibited by submersion in the Kurose River estuary of Japan (Sasaki et al 2009). These studies were conducted across the semi-diurnal cycle, mainly in STP when soils were inundated or water-saturated most of the time.…”

Saprobity: a unified view of benthic succession models for coastal lagoons

“…The marine water supply usually conveys dissolved oxygen (DO) to the system. Moreover, exposure to the air of intertidal sediments at low tide significantly increases mineralization rates (Sasaki et al, 2009). Remineralization processes can be enhanced by water mixing because of both oxygenation and increased contact of catabolites with various kinds of surface, such as bottom sediments, suspended matter and other physical and biological components (e.g.…”