Anthropogenic Nitrogen‐Induced Changes in Seasonal Carbonate Dynamics in a Productive Coastal Environment

Abstract

We estimated the seasonal extremes in pH and the aragonite saturation state (Ωarag) for the Yellow Sea over the past 30 years using recent (2015–2018) carbonate data sets, along with historical data sets of surface N and bottom water dissolved O2 concentrations. The rate of increase in surface N was assumed to determine the postbloom surface dissolved inorganic C concentration resulting from the complete utilization of N by phytoplankton, while the decrease in bottom water O2 was assumed to reflect the prebloom surface C, as a consequence of C‐rich bottom water (resulting from the oxidation of greater amounts of organic matter transported from the surface) being brought to the surface. With the increasing loads of anthropogenic N, the net community metabolism (an increase in organic matter production at the surface and subsequent remineralization at the seafloor) has lowered the seasonal amplitude of pH by 0.14 but increased the amplitude of Ωarag by 0.8.

Climate‐Driven Fluctuations in Anthropogenic CO2 Uptake by the East Sea in the North Pacific Ocean

“…To validate the resulting rate, we also cross‐checked our finding using additional C T data set from Kim et al. (2020) collected from the coast of Korea for the period 2010 to 2021 (solid circles in Figure 1e). For all of our analyses, we considered data from the maximum winter mixed layer, which extended to a depth of 300 m. This depth was determined based on seawater density gradients (Lim et al., 2012).…”

“…To determine the rate of surface C ANTH increase during the study period from spanning 1992 to 2019, we applied linear regression to all C T data acquired from four surveys conducted in the northern basin of the East Sea. To validate the resulting rate, we also cross-checked our finding using additional C T data set from Kim et al (2020) collected from the coast of Korea for the period 2010 to 2021 (solid circles in Figure 1e). For all of our analyses, we considered data from the maximum winter mixed layer, which extended to a depth of 300 m. This depth was determined based on seawater density gradients (Lim et al, 2012).…”

Persistent Continental Shelf Carbon Sink at the Ieodo Ocean Research Station in the Northern East China Sea

“…How the C uptake status of the northern ECS has evolved and how it will change are noteworthy. Because the northern ECS has increasingly received anthropogenic nutrients over the past 40 years via the CDW and, to a lesser extent, atmospheric deposition (Kim et al, 2020;Zheng and Zhai, 2021), the region has grown fertile in phytoplankton and thus, removed surface C in the form of organic matter. Much of the organic matter has likely been buried in the shallow marine sediments there.…”

The Diel and Seasonal Heterogeneity of Carbonate Chemistry and Dissolved Oxygen in Three Types of Macroalgal Habitats

“…The coastal ocean experiences large fluctuations in its carbonate chemistry due to both hydrodynamic and biological activities (Lee et al, 2011;Cai et al, 2020;Kim et al, 2020b). In fact, variability in seawater pH within some coastal oceans can be greater than that in the open ocean (Hofmann et al, 2011).…”

“…Indeed, total macroalgal biomass is high in winter and spring, and low in summer and autumn. In addition, opportunistic macroalgae have become abundant in coastal areas with intensive nutrient inputs (Lee and Kang, 2020;Kim et al, 2020b;Kang et al, 2021), while coralline algae have become dominant in other areas because of climate change and increased herbivore pressure on fleshy macroalgae (Kim et al, 2020a). Over time, these macroalgal communities are turning into tiny mosaics with strong spatial heterogeneity.…”