pCO2 and carbon fluxes across sea-air interface in the Changjiang Estuary and Hangzhou Bay

Partial pressure of CO2 (pCO2) was investigated in the Changjiang (Yangtze River) Estuary, Hangzhou Bay and their adjacent areas during a cruise in August 2004, China. The data show that pCO2 in surface waters of the studied area was higher than that in the atmosphere with only exception of a patch east of Zhoushan Archipelago. The pCO2 varied from 168 to 2 264 μatm, which fell in the low range compared with those of other estuaries in the world. The calculated sea-air CO2 fluxes decreased offshore and varied from −10.0 to 88.1 mmol m−2 d−1 in average of 24.4 ± 16.5 mmol m−2 d−1. Although the area studied was estimated only 2 × 104 km2, it emitted (5.9 ± 4.0) × 103 tons of carbon to the atmosphere every day. The estuaries and their plumes must be further studied for better understanding the role of coastal seas playing in the global oceanic carbon cycle.