Spatial Variation in Aragonite Saturation State and the Influencing Factors in Jiaozhou Bay, China

Abstract

Both natural processes and human activities affect seawater calcium carbonate saturation state (Ωarag), while the mechanisms are still far from being clearly understood. This study analysed the seawater surface Ωarag during summer and winter in Jiaozhou Bay (JZB), China, based on two cruises observations performed in January and June 2017. The ranges of Ωarag values were 1.55~2.92 in summer and 1.62~2.15 in winter. Regression analyses were conducted to identify the drivers of the change of Ωarag distribution, and then the relative contributions of temperature, mixing processes and biological processes to the spatial differences in Ωarag were evaluated by introducing the difference between total alkalinity (TA) and dissolved inorganic carbon (DIC) as a proxy for Ωarag. The results showed that biological processes were the main factor affecting the spatial differences in Ωarag, with relative contributions of 70% in summer and 50% in winter. The contributions of temperature (25% in summer and 20% in winter) and the mixing processes (5% in summer and 30% in winter) were lower. The increasing urbanization in offshore areas can further worsen acidification, therefore environmental protection in both offshore and onshore is needed.

Spatio-temporal variation of major ion chemistry and nutrient stoichiometry in a tropical monsoonal estuary: insight into biogeochemical processes

“…Spatially, increase in the SI Cal , SI Arag and SI Dol are observed towards the mouth of estuary during summer and winter (Fig.6). Similar, distribution of SI along the salinity gradient has been reported in several other estuaries(Jiang et al 2010;Wit et al 2018;Li et al 2020).…”

“…The Signi cant positive correlation between pH and SI values is found in the estuary (Table S1). Dependency of SI on pH of water is well reported by various authors (Abril et al 2003;Li et al 2020). An increase in pH towards the mouth of estuary is evident from its positive correlation with salinity (Table S1).…”

Distribution of Carbon and Nitrogen as Indictors of Environmental Significance in Coastal Sediments of Weizhou Island, Beibu Gulf

“…Continental margin sediments contain more than 90% of the carbon buried in the ocean, and the estuary coastal zone, as a sensitive exchange zone for sea-land carbon pools, effectively indicates that the global carbon cycle process is driven by sea level changes [1,2]. However, as an open system, the biogeochemical signals of coasts are complex due to the influence of multiple natural factors (such as global coastline and paleoclimate changes) and the interference of human activities [3][4][5][6][7].…”

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).…”