Large accumulation of anthropogenic CO₂ in the East (Japan) Sea and its significant impact on carbonate chemistry

Abstract

[1] This paper reports on a basin-wide inventory of anthropogenic CO 2 in the East (Japan) Sea determined from high-quality alkalinity, chlorofluorocarbon, and nutrient data collected during a summertime survey in 1999 and total dissolved inorganic carbon data calculated from pH and alkalinity measurements. The data set comprises measurements from 203 hydrographic stations and covers most of the East Sea with the exception of the northwestern boundary region. Anthropogenic CO 2 concentrations are estimated by separating this value from total dissolved inorganic carbon using a tracerbased (chlorofluorocarbon) separation technique. Wintertime surface CFC-12 data collected in regions of deep water formation off Vladivostok, Russia, improve the accuracy of estimates of anthropogenic CO 2 concentrations by providing improved airsea CO 2 disequilibrium values for intermediate and deep waters. Our calculation yields a total anthropogenic CO 2 inventory in the East Sea of 0.40 ± 0.06 petagrams of carbon as of 1999. Anthropogenic CO 2 has already reached the bottom of the East Sea, largely owing to the effective transport of anthropogenic CO 2 from the surface to the ocean interior via deep water formation in the waters off Vladivostok. The highest specific column inventory (vertically integrated inventory per square meter) of anthropogenic CO 2 of 80 mol C m À2 is found in the Japan Basin (40°NÀ44°N). Comparison of this inventory with those for other major basins of the same latitude band reveal that the East Sea values are much higher than the inventory for the Pacific Ocean (20À30 mol C m À2 ) and are similar to the inventory for the North Atlantic (66À72 mol C m À2 ). The substantial accumulation of anthropogenic CO 2 in the East Sea during the industrial era has caused the aragonite and calcite saturation horizons to move upward by 80À220 m and 500À700 m, respectively. These upward movements are approximately 5 times greater than those found in the North Pacific. Both the large accumulation of anthropogenic CO 2 and its significant impact on carbonate chemistry in the East Sea suggest that this sea is an important site for monitoring the future impact of the oceanic invasion of anthropogenic CO 2 .

State of the Climate in 2010

“…Annually varying global air-sea CO 2 flux estimates are based on empirical approaches relating in situ measurements with satellite observations of wind and sea surface temperature (Sabine et al 2008(Sabine et al , 2009(Sabine et al , 2010. The latest empirical approach for quantifying the air-sea CO 2 exchange utilizing in situ, climatological, and satellite data from 1982 to 2007 is described in Park et al (2010). Gruber et al (2009) estimate that the pre-industrial steady state ocean was a source of 0.45 Pg C yr -1 , the estimated average net flux equates to an ocean anthropogenic CO 2 uptake of 1.92 Pg C yr -1 , at the lower end of the range of estimates (1.8 Pg C yr -1 -2.4 Pg C yr -1 ) recently summarized by Gruber et al (2009).…”

Calcium carbonate saturation in the surface water of the Arctic Ocean: undersaturation in freshwater influenced shelves

“…Since the industrial revolution, the surface ocean pH has dropped by 0.1 units (Caldeira and Wickett, 2003) and is projected to drop another 0.3 ito 0.4 units by 2100 (Feely et al, 2004;Orr et al, 2005). The increase of anthropogenic CO 2 has led to the shallower carbonate saturation horizon of several hundred of meters in the Japan Sea (Park et al, 2006). Several laboratory studies have shown that reduction in levels of CaCO 3 saturation reduces calcification in marine calcifiers, such as calcifying phytoplankton (e.g.…”

Seasonal Variations of Surface fCO2 and Sea-Air CO2 Fluxes in the Ulleung Basin of the East/Japan Sea

“…The average depth of the East Sea is 1740 m, and it connects to the western North Pacific through four shallow straits with depths less than 140 m. Because of the shallow depths of these straits, subsurface waters below the thermocline (located at about 100 ~ 200 m) cannot be directly exchanged between the East Sea and North Pacific. Due to high biological productivity and accumulation of anthropogenic CO 2 (Yamada et al 2005; Park et al 2006;Yoo and Park 2009), the East Sea could be an important marginal sea in which to study oceanic carbon cycles. However, relatively few studies have investigated sea-air CO 2 fluxes in the southwestern part of the East Sea, the Ulleung Basin (Oh 1998;Kang 1999;Choi et al 2011).…”