Figure 8. The correlation between “AT – CT” and AOU in surface water (depth ≤ 20 m) and deep waters (depth > 100 m).
The green regression line intersects the y-axis at zero when AOU is at its peak, aligning with predicted aerobic respiration, especially when there is a notable increase in CT compared to AT (Figures 7 and 8). In contrast, the black regression line does not meet the zero line when AOU is elevated, as the data influenced by anaerobic processes exerts an upward pull on the line. This phenomenon is linked to processes that yield higher AT and not solely CT, such as CaCO3 dissolution (Xue and Cai, 2020) or anaerobic processes like sulfate reduction and denitrification.