北黄海海水中挥发性卤代烃的分布和海-气通量研究

Distributions and sea-air fluxes of volatile halocarbons in the seawater of the northern Huanghai Sea

用吹扫-捕集气相色谱法对北黄海常见的4种挥发性卤代烃（VHC）的研究表明,秋季北黄海表层海水中CHCl3,C2HCl3,CHBr2Cl和CHBr3的浓度和平均值分别为9.9~63.4（14.1±8.1）,7.1~29.4（15.4±6.2）,0.1~30.3（8.8±10.0）和4.2~56.4（21.6±12.2）pmol/dm3。这4种VHC在水平分布上呈现一定的空间变化,其浓度可能是陆地径流、人为活动和生物产生的影响程度不同造成的。VHC在垂直分布上受到地理位置和水文条件的不同影响,在不同站位有较大差异。周日变化研究表明,VHC具有一定的周日变化特征,受光照和潮汐等因素的共同影响最大值均出现在13：00—16：00。采用Liss和Slater双层模型理论对北黄海表层海水和大气之间CHCl3,C2HCl3和CHBr3的海-气通量进行估算,得到这3种物质在北黄海的海-气通量平均值和范围分别为14.8（0.2~104.4）,23.2（1.8~93.0）和15.6（0.7~55.1）nmol/（m2.d）。结果表明,在秋季该研究海域是大气CHCl3,C2HCl3和CHBr3的源。

The concentrations of four kinds of volatile halocarbons（VHCs） in the seawater of the northern Huanghai Sea（NHS） were systematically measured.The results show that the concentrations of CHCl3,C2HCl3,CHBr2Cl and CHBr3 in the surface seawater in the NHS are 9.9~63.4（14.1±8.1）,7.1~29.4（15.4±6.2）,0.1~30.3（8.8±10.0） and 4.2~56.4（21.6±12.2）pmol/dm3,respectively.The concentrations of the 4 VHC in the surface seawater showed a certain degree of spatial variation,which may be subject to different effects of riverine input,human activities and biological produce.The depth and intensity of maxima of the four kinds of VHC coneentration in the vertical distributions are different among stations,due to different geographical locations and different effects of hydrological conditions.Therefore,no obvious consistency of the vertical profiles of VHC was observed.The concentrations of four kinds of VHC exhibited a clear diurnal variation in the surface seawater,with the highest concentrations appearing between 13：00 and 16：00,presumably due to co-effect of illumination,tide and other factors at this time.On the basis of gas exchange calculations,the mean sea-to-air fluxes of CHCl3,C2HCl3 and CHBr3 were estimated to be,respectively,14.8（0.2~104.4）,23.2（1.8~93.0）and 15.6（0.7~55.1） nmol/（m-2·d）,indicating that the study area appears to be a source of atmospheric CHCl3,C2HCl3 and CHBr3 during the investigated time.