Preliminary Studies On Five Kinds Of Volatile Halocarbons In The Yellow Sea And The East China Sea

Volatile halocarbons are important trace gases in the atmosphere. Most of them are greenhouse gases and organic pollutants, which are effecting the human's healthy and the global climate directly or indirectly. Studies on the VHCs in the ocean help to learn the ocean contribution to the atmosphere's VHCs and the important effect of the ocean on the global climate. At the same time, the recycling ways of some kinds of VHCs are contributed to learn the motions of water masses in the ocean as trace gases.The Purge and Trap method is used in this article to study the distributions, influencing factors and air-sea fluxes of vinylidene chloride (VDC), 1, 1, 1-trichloroethane (MCF), Chloroform (CHCl3), Carbon Tetrachloride (CCl4) and Trichloroethylene (TCE) in the North Yellow Sea during cruise 908, in the South Yellow Sea and the East China Sea during cruise 973, in the South Yellow Sea during cruise Enteromorpha prolifra and in the South Yellow Sea and the East China Sea during cruise 863. The results of this article are as follows:1. Optimize the experimental and chromatographic conditions. Establish the method for detecting 5 kinds of VHCs. The detection limits of VDC, MCF, CHCl3, CCl4 and TCE are up to 1.45 pmol/L, 0.21 pmol/L, 0.76 pmol/L, 0.04 pmol/L and 0.10 pmol/L, respectively. The average relative standard deviation (RSD) is 5.95%. The recovery of the VDC is 78%-87%, while the recovery of MCF is 89%～92%, the recoveries of CHCl3, CCl4 and TCE are 108.9%, 110.2% and 105.4%, respectively.2. Data of cruise 908: the concentration ranges of VDC, MCF, CHCl3, CCl4 and TCE are 3.44～40.3 pmol/L, 0.271～1.66 pmol/L, 4.97～50.0 pmol/L, 0.496～3.04 pmol/L and 0.108～0.783 pmol/L, respectively; and the average values are 14.98±7.75 pmol/L, 0.793±0.337 pmol/L, 12.6±8.08 pmol/L, 1.65±0.489 pmol/L and 0.311±0.191 pmol/L, respectively. The sea-air flux ranges of MCF, CHCl3, CCl4, and TCE during cruise 908 are -10.4～-5.35 nmol·m^-2·a^-1, 6.09～73.1 nmol·m^-2·a^-1, -5.17～3.22 nmol·m^-2·a^-1 and -2.73～-0.187 nmol·m^-2·a^-1; while the average values are -8.38±1.23 nmol·m^-2·a^-1, 27.0±15.3 nmol·m^-2·a^-1, -1.26±1.63 nmol·m^-2·a^-1 and -1.83±0.665 nmol·m^-2·a^-1, respectively.3. Data of cruise 973: the concentration ranges of VDC, MCF, CHCl3, CCl4, and TCE are 2.75～21.3pmol/L, 0.312～4.81pmol/L, 5.02～233pmol/L, 0.0452～4.47pmol/L and 1.21～17.1pmol/L, respectively; while the average values are 12.2±4.43 pmol/L, 1.89±1.08 pmol/L, 60.9±61.2 pmol/L, 0.332±0.674 pmol/L and 6.93±3.95 pmol/L, respectively. The sea-air flux ranges of MCF, CHCl₃, CCl₄, and TCE during cruise 973 are -15.9～7.63 nmol·m^-2·a^-1, 4.96～1.03×10³ nmol·m^-2·a^-1, -11.1～-5.95 nmol·m^-2·a^-1 and 4.01～85.4 nmol·m^-2·a^-1; while the average values are -6.69±5.39 nmol·m^-2·a^-1, 304±322 nmol·m^-2·a^-1, -8.69±1.31 nmol·m^-2·a^-1 and 33.4±21.8 nmol·m^-2·a^-1, respectively.4. Data of cruise Enteromorpha prolifra shows: the concentration ranges of VDC, MCF, CHCl₃, CCl₄, and TCE are 25.3～77.2 pmol/L, 19.2～218 pmol/L, 87.7～802 pmol/L, 9.97～21.9 pmol/L and 1.24～23.6 pmol/L, respectively; while the average values are 53.4±12.3 pmol/L, 63.6±44.3 pmol/L, 359±177 pmol/L, 15.6±2.74 pmol/L and 11.1±4.97 pmol/L, respectively. The sea-air flux ranges of MCF, CHCl₃, CCl₄, and TCE during cruise Enteromorpha prolifra are 52.9～411 nmol·m^-2·a^-1, 2.93×10²ï½ž2.71×10³ nmol·m^-2·a^-1, 25.0～63.1 nmol·m^-2·a^-1 and 13.6～79.1 nmol·m^-2·a^-1; while the average values are 172±94.9 nmol·m^-2·a^-1, 1.20×10³Â±601 nmol·m^-2·a^-1, 42.2±9.22 nmol·m^-2·a^-1 and 35.1±15.8 nmol·m^-2·a^-1, respectively.5. Data of cruise 863 shows: the concentration ranges of VDC, MCF, CHCl3, CCl4, and TCE are 14.3～87.2 pmol/L, 10.1～99.5 pmol/L, 94.5～958 pmol/L, 5.65～23.3 pmol/L and 3.49～19.3 pmol/L, while the average values are 44.2±20.5 pmol/L, 44.9±22.0 pmol/L, 313±229 pmol/L, 12.5±4.96 pmol/L and 10.5±4.08 pmol/L, respectively. The sea-air flux ranges of MCF, CHCl₃, CCl₄, and TCE during cruise 863 are 0.0364～1.97 nmol·m^-2·a^-1, 2.02～21.2 nmol·m^-2·a^-1, 0.0792～0.407 nmol·m^-2·a^-1 and 0.0586～0.384 nmol·m^-2·a^-1, respectively.6. It can be found from the data that the high concentration of VHCs near shore are by the impact of industry and humans life; but in the sea, the concentration of VHCs are by the impact of marine masses and cold or warm current, the high value areas appear in the sea area where the marine organisms are dense. In the whole, the high value areas appear at the zooms where the cold current and the warm current are together or water masses interact violently. Data of section F03 and F05 during cruise 973 shows: there is a trend that the concentrations near shore are higher than that in the sea; the concentrations in the surface are higher than that in the bottom. In addition, marine organisms'activities may cause the high value area in the middle and the bottom. Overall, except CHCl3 in the autumn, marine is a sink for MCF, CCl4 and TCE, while it is a source in the summer for MCF, CHCl3, CCl4 and TCE.