Variations of pCO2 and sea-air CO2 flux in Qingdao coastal seawater in spring based on buoy observations

doi:10.3969/j.issn.1001-909X.2023.03.002

Abstract

Abstract:

Based on the high frequency data of sea-air interface buoys, the variation pattern and driving factors of sea-air partial pressure of carbon dioxide (pCO₂) were analyzed and the sea-air CO₂ flux in the coastal waters of Qingdao in spring was estimated. During the observation period, the sea area changed from a carbon sink of atmospheric CO₂ to a carbon source, which was mainly caused by the continuous increase of sea surface pCO₂. By analyzing the controlling factors of pCO₂, it was found that temperature was the main driving factor of pCO₂ growth, and biological processes played a certain inhibiting role. The sea surface pCO₂ showed a diurnal variation. The effects of temperature and biological factors on the diurnal variation of pCO₂ were related to solar radiation, but they had opposite effects. In addition, the analysis showed that different sampling frequencies of buoys affected the estimation of sea-air CO₂ flux and shortening the sampling interval could effectively reduce the deviation of CO₂ flux estimation and improve the accuracy of estimation.

Key words: pCO₂, sea-air flux of CO₂, buoy observation, Qingdao coastal waters

CLC Number:

P734.45

ZHOU Xuehang, ZHANG Honghai, MA Xin, CHEN Zhaohui. Variations of pCO₂ and sea-air CO₂ flux in Qingdao coastal seawater in spring based on buoy observations[J]. Journal of Marine Sciences, 2023, 41(3): 14-21.

Figures/Tables 6

Fig.1 Sketch map of study area and buoy location

Fig.2 Time series of sea surface and atmospheric pCO2, exchange fluxes and related environmental parameters

Fig.3 Time series of daily mean sea surface pCO2 and related influencing factors

Fig.4 Time series of sea surface pCO2 and tide height

Fig.5 Diurnal cycle of sea surface pCO2, SST and shortwave radiation (The shaded part represents a range of standard deviations.)

Fig.6 Violin-plot of daily mean sea-air CO2 flux deviation for different sampling periods (The black bars represent the interquartile range of the daily mean data, the white dots represent the median, and the outer contours represent the kernel density curve of the daily mean data.)

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Variations of pCO₂ and sea-air CO₂ flux in Qingdao coastal seawater in spring based on buoy observations

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