Program

Continual increase of anthropogenic CO₂ input to the ocean is important to assess to determine the ocean’s mutable function as a sink and scrutinize acidification rate. We sought to examine anthropogenic carbon penetration into a major world marginal sea, the South China Sea. Dissolved inorganic carbon, total alkalinity, dissolved oxygen, nutrient parameters, CFC-11, and CFC-12 samples were collected onboard the R/V Dongfanghong II during the summer (28^th May – 5^th July) within the northern South China Sea (nSCS) Basin and from the West Philippine Sea. Carbonate and nutrient parameters were analyzed at Xiamen University, China. CFC-11, and CFC-12samples were analyzed at Columbia University, U.S.A. These parameters were incorporated into back-calculation and transient tracer distribution methods to establish the anthropogenic carbon (C_ant.) inventory in the study region. Preliminary results for the summer 2014 dataset show that the C_ant. values derived from the back-calculation method were in good agreement with C_ant. values derived from the transient tracer distribution method. In the upper 100m, C_ant. concentrations were higher in the South China Sea than values in the West Philippine Sea. The average Ω_Ar.horizon in the SCS is 70-90m shallower than previous studies and exhibit spatial variability. The majority of the C_ant. concentration distribution in the study region are correlated with depth fluctuations in Ω_Ar. Horizon. C_ant. penetration is observed in the nSCS deep water (n=11, 8.79 µmol kg^-1 ± 3.90, via back-calculation; n=13, 6.46 µmol kg^-1 ± 0.90, via transient tracer distribution; P>0.050) that is defined as >2000m. These results suggested a much deeper C_ant. penetration as compared to prior assessments about 15 years ago. Potential explanations include increased concentrations from North Pacific Deep Water and/or enhanced biological productivity within the South China Sea.