Academic journal article Journal of Sustainable Development

The Method Estimating Daytime CO2 Flux between Intertidal Sediment and the Atmosphere

Academic journal article Journal of Sustainable Development

The Method Estimating Daytime CO2 Flux between Intertidal Sediment and the Atmosphere

Article excerpt

Abstract

The daytime variation in CO2 flux between the intertidal sediment and the atmosphere was great and impacted by environmental elements. This paper analyzed the daytime variation in CO2 flux between the intertidal sediment and the atmosphere and concluded its different rules during the ebb tide and flood tide. During the ebb tide, the CO2 flux rose as the tide ebbed and its rate of change was different when the redox potential changed (0.13 μmol m^sup -2^ s^sup -1^ per 100 cm height of the tide at Eh ≤ 300 mv, 0.15 μmol m s^sup -2^ s s^sup -1^ per 100 cm height of the tide at 300 mv < Eh < 500 mv and 0.07 μmol m s^sup -2^ s s^sup -1^ per 100 cm height of the tide at Eh ≥ 500 mv). During the flood tide, the CO2 flux maintained the largest of the day and almost unchanged with the increase of water level. The average CO2 flux in the flood tide increased with the increase of the redox potential at Eh ≤ 300 mv and 300 mv < Eh < 500 mv, but their linear regressions between the average CO2 flux and the redox potential were different. Compared with the average CO2 flux at Eh ≤ 300 mv and 300 mv < Eh < 500 mv, the average CO2 flux was no longer related to the redox potential but related to temperature at Eh ≥ 500 mv. According to these rules, the daytime CO2 flux can be calculated based on limited measurements well and truly. The fitting straight line equation between the estimated and measured CO2 flux was y= 0.9353x+0.0872 (R s^sup -2^ = 0.75, P < 0.01).

Keywords: intertidal zone, CO2 flux, redox potential

(ProQuest: ... denotes formulae omitted.)

1. Introduction

Since global warming become the hot topic, a series of research projects have been trying to give a precise CO2 flux between various ecosystems and the atmosphere. The intertidal zone is the junction of land and sea. It is also a special and important type of wetland. The biogeochemistry environment is complex and unconstant. These properties lead to distinct CO2 exchange mode between intertidal zone and the atmosphere. According to statistics, there are 2.17×104 km2 of the intertidal zone in China (Lei & Zhang, 2005). Although we need a relatively independent CO2 flux research on capacious intertidal zone, the observation on the intertidal zone with static chamber and eddy covariance method was limited (Magenheimer, Moore, Chmura, & Daoust, 1996; Yang et al., 2006; Wang et al., 2007). Mo et al. (2005) estimated the soil respiration based on soil temperature in forest ecosystems; the estimation results were in good agreement with the measured results. Compared with the quantitative estimate of soil respiration in other ecosystems (Davidson, Belk, & Boone, 1998), there has been no similar research on intertidal zone so far. How to give a precise calculation of CO2 flux between intertidal zone and the atmosphere? This paper intends to give a method estimating CO2 flux between intertidal zone and the atmosphere. The method was based on the daytime course of CO2 flux between intertidal sediments and the atmosphere.

2. Materials and Methods

2.1 Study Site

This paper selected the Beach (36°05.327'N, 120°27.675'E) of the Shilaoren Scenic Area, Qingdao, China (Figure 1) as the study site. The study site is on the west side of Shilaoren statue. It located between Gaodijiao and Fushanjiao. The length of the beach is about 2.5 kilometers and beach area is about 0.55 km2. The average slope of the beach is 1.5%. The observation site is ~0.7 m above the sea level.

The salinity of the offshore seawater ranged from 26 to 28, because of the impact of the rivers at sourthern Laoshan (about 20 km away). The average temperature of the surface water is 13.5 °C. The observation site is 5 km away from the Maidao Marine Environmental Monitoring Station, Qingdao (www.nmfc.gov.cn). We collected the tide data from this station. The annual mean wave height is 0.7 m. The tide is semi-diurnal. The average high tide is 3. …

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