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Studies on the Distributions and Sea-to-air Fluxes of Volatile Halocarbons in the East China Sea, The Yellow Sea and the Northern South China Sea

Author: YangBin
Tutor: YangGuiPeng
School: Ocean University of China
Course: Marine Chemistry
Keywords: Volatile halogenated hydrocarbons East China Sea Yellow Sea South China Sea Distributed Air - sea flux
CLC: P734.22
Type: Master's thesis
Year: 2010
Downloads: 38
Quote: 1
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Abstract

Volatile halogenated hydrocarbons VHCs (Volatile halocarbons) is an important trace greenhouse gases in the atmosphere and the ozone layer destroyer, plays an important role in terms of global climate change and the ecological environment. The atmosphere of volatile halogenated sources are mainly two kinds of naturally occurring and man-made activities, where the ocean is an important natural source of atmospheric volatile halogenated hydrocarbons. The marine interfacial layer is water - one of the important place of the gas exchange between the atmosphere and therefore the ocean can be both a source of atmospheric VHCs may also sink. Marine sources and sinks of atmospheric VHCs balance plays an important role, so to carry out the marine environment VHCs research has great significance. Representative of the paper to China in the East China Sea and the Yellow Sea shelf sea, and the northern part of the South China Sea continental shelf - slope - deep-sea areas as research target, the VHCs concentration and several common in these waters, spatial and temporal changes in the air - sea flux The influencing factors were studied, to provide a scientific basis to enrich our the VHCs research in the marine field, objective estimate the contribution of the China Sea on the regional and global environmental change. The main findings of the paper are as follows: (1) determination of the VHCs the based on the purge and the - trap gas chromatography laboratory has been established, the analysis measured seawater common VHCs are: chloroform (CHCl3) , carbon tetrachloride (CCl4), trichlorethylene (C2HCl3), bromodichloromethane (CHBrCl2), of a chlorine dibromomethane (CHBr2Cl) and bromoform (CHBr3). optimization of the experimental conditions and the chromatographic conditions, the method detection limits were 0.25 pmol L-1 CHCl3, 0.03 pmol L-1CCl4, 0.08 pmol L-1 C2HCl3, 0.01 pmol L-1 CHBrCl2, 0.16 pmol L-1 CHBr2Cl and 0.12 pmol of L-1 CHBr3 relative standard deviation between the range of 1.82% -3.98%, recoveries between 87.3% -109.4%, quite similar foreign methods. The establishment of the method for the determination of the northern part of the East China Sea, the Yellow Sea and the South China Sea seawater VHCs work has laid a solid foundation. (2) in April-May 2009, the East China Sea and the Yellow Sea VHCs concentration distribution and air - sea flux. The results show that the surface waters of CHCl3 the the in CCl4, C2HCl3, CHBrCl2, CHBr2Cl and CHBr3 average concentration and range were 42.19 (2.57-139.76), 2.91 (0.06-13.49), 17.85 (2.67-41.99), 24.47 (7.17-45.71) , 6.31 (0.47-30.45) and 10.09 (5.54-21.93) pmol L-1. Six kinds of surface waters in the East China Sea and the Yellow Sea the VHCs the horizontal distribution presents some characteristics of the distribution. Anthropogenic emissions, mainly from the horizontal distribution of CHCl3, the CC14 and C2HCl3 concentration generally near-shore, off the coast of trend. Invasion due to the low-nutrient, low Chl-a high-temperature, high-salt, the black tide in the eastern waters of the continental shelf of the East China Sea, the three concentrations of low value area. Students based the CHBrCl2, CHBr2Cl and CHBr3 prone areas, high levels of distribution frequency of red tide in the Yangtze Estuary. Studies have shown that cross-section of the vertical distribution of the six kinds the VHCs in each cross-section showing the different distribution characteristics. A Sunday Change Research Overall, students produce 5 the VHCs concentration diurnal variation influenced by light and temperature by larger, the smaller the impact of human-generated CCl4. The linear regression analysis showed the seawater temperature CHBrCl2 significant negative correlation, of salinity and CHBr2Cl the negative correlation is obvious. In six kinds VHCs, only CHBrCl2 the Chl-a there is a positive correlation. The air-sea flux studies have shown that, during the investigation of the voyage, the East China Sea and Yellow Sea CCl4 exchange, is the source of C2HCl3, CHBrCl2 and CHBr2Cl CHCl3 and CHBr3, in addition to some of the stations unsaturated, most of the waters of the performance out their source. Shows shelf sea accounts for only a small portion of the world's oceans, but the air-sea flux estimate the global ocean in six kinds VHCs should not be ignored. (3) in March-April 2009, the concentration distribution of the northern waters of the South China Sea VHCs and air - sea flux. The results show that surface waters CHCl3, C2HCl3 CHBrCl2 and CHBr3 average concentration and range were 6.47 (0.88-27.02), 1.44 (0.31-6.79), 3.12 (0.35-6.76), and 23.39 (5.84-32.12) pmolL-1. Four kinds VHCs presented in the horizontal distribution of certain characteristics of the distribution. The maximum concentration of in CHCl3, CHBrCl2, and C2HCl3 of NO1 survey the waters of the northern continental slope area N02 and N03 stations; the CHBr3 highest value and high-value area also appear in this sea area in the western slope zone QB4 station; CHCl3, the CHBrCl2 and CHBr3 in the Kuroshio area showed a low concentration of the phenomenon, but C2HCl3 higher value in the region. Diurnal variation study, four kinds VHCs in general daytime concentration is relatively high, but lower concentrations at night, they are subject to the effects of light and water temperature is relatively large. Linear regression analysis showed that, the existence between CHBrCl2 and C2HC13 significant positive correlation significant negative correlation between the CHBrCl2 seawater temperature. Air - sea flux research shows that overall the survey on the sea area is the source of these four kinds of in CHCl3, C2HCl3, CHBrCl2 and CHBr3 VHCs.

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