The spatiotemporal variation and control mechanism of surface pCO2 in winter in Jiaozhou Bay, China

Abstract

In many mid-latitude coastal waters during winter months, in addition to temperature, the large change in biogeochemical processes often influence and complicate the surface partial pressure of CO2 (pCO2). Based on the hydrological and carbonate parameters in seven cruises, this study analysed the evolution process and explored the control mechanism of the surface pCO2 in Jiaozhou Bay, China, from December to March. The results showed that the pCO2 ranged from 157 μatm to 647 μatm, and the bay represented a sink for atmospheric CO2 (-3.8 mmol m -2 d -1 ) in the whole winter. The non-temperature processes were the dominant factors affecting intra-winter pCO2 variation. In December, the bay was dominated by aerobic respiration and acted as a CO2 source (3.0 mmol m -2 d -1 ). From early January to late February, however, the vigorous growth of cold algae caused strong primary production, and the bay presented as a CO2 sink (from -6.4 mmol m -2 d -1 in early January to -15.5 mmol m -2 d -1 in late February). In March, primary production weakened and the effects of the CaCO3 precipitation appeared, and the strength of the CO2 sink was obviously weakened (-1.1 mmol m -2 d -1 ). Meanwhile, the water temperature decreased gradually from December to late January and then increased until March, and it further expanded the variation range of pCO2. Our results highlight the obvious source/sink change in mid-latitude seawater CO2 in winter, while more field observations are still needed to further understand the complicated biogeochemical processes and its influence on seawater pCO2.

Spatial variations in CO2 fluxes in a subtropical coastal reservoir of Southeast China were related to urbanization and land-use types

“…This resulted in the direct input of dissolved CO2 into the Wenwusha Reservoir, and subsequently a larger CO2 diffusive flux because of the steeper CO2 concentration gradient between the surface water and the atmosphere. Therefore, the discharge of CO2-rich wastewater can directly contribute to CO2 oversaturation in some polluted waters and lead to high CO2 emissions from reservoir water to the atmosphere (Li et al, 2020a;2020b).…”

The Carbonate System of Penzhina Bay and the Shelikhov Gulf in the Sea of Okhotsk during Extreme Tides in Summer

“…Calculations of the FCO 2 can be subject to large uncertainties due to the difficulty in accurately estimating this gas transfer rate (for example, see the discussion in [16]). Daily and tidal oscillations of the pCO 2 in the water of fast-moving coastal ecosystems can also add some uncertainty to estimates of the FCO 2 in the air and water due to a large set of controlling factors [14,17,18].…”