辽东湾北部海域表层沉积物氧化还原电位及其主要影响因素

通过2007年秋季对辽东湾北部海域表层沉积物氧化还原电位（Eh）的现场调查，分析了该海域表层沉积物Eh的现状，并从底质特性、上覆海水以及河流输入等方面深入探讨了Eh的影响因素。结果表明，该海域表层沉积物Eh变化范围在-24.8 mV~-366.7 mV之间，已由20世纪90年代的O2/H2O、有机物、MnO2/Mn2+、Fe(OH)3/Fe2+体系控制的弱还原环境转变为由SO2-4/HS-、S/HS-体系控制的还原环境，分布基本呈现自辽东湾东北部向西南部逐渐降低的趋势。表层沉积物中有机质是氧化还原反应必不可少的因子，但可能由于调查海域沉积速率较高和较强的还原环境的影响，有机质对Eh的分布及变化影响不明显；表层沉积物中硫化物含量和温度的高低直接影响到Eh，Eh随着硫化物含量和温度的升高而降低。上覆海水中溶解氧含量的高低也是影响Eh的一个重要因素，尤其是在溶解氧含量相对较高的调查海域影响更为显著，Eh呈现随着溶解氧的降低而降低的趋势。另外，河流输入也是影响该调查区域Eh的一个重要因素，但影响范围主要在以双台子河口为中心的冲淡水能达到扇形区域内。近二十年来，陆源排污及海上养殖等人类活动不断加强，造成了有机质与硫化物等污染物质的不断增加，使得辽东湾北部海域表层沉积物Eh逐渐降低，氧化还原环境发生了明显转变，同时表层沉积物的温度、上覆海水溶解氧、河流的输入及其与海水的混合作用等多种因素造就了该海域目前的氧化还原电位的分布变化特征，也一定程度上反映着该地区的污染分布状况，因此有必要采取相应措施，加强对该海区的环境保护力度，保持地区经济的可持续发展。

The Eh in Surface Sediments in the Northern of Liaodong Bay and Its Main Influencing Factors

The redox potential(Eh) of the surface sediments in the northern waters of Liaodong Bay was directly measured in the autumn of 2007,and the distribution and its main factors including sediments characteristics,the overlying seawater,and river input was studied deeply.The results indicate that: the Eh of the surface sediments ranges between-24.8 mv and-366.7 mv,which means the environment has changed from weak reductive system controlled by O2/H2O,organic matter,MnO2/Mn2+ and Fe(OH)3/Fe2+ in the 1990s to reductive system now mainly controlled by SO2-4/HS-,S/HS-and furthermore,there are significant variations in the spatial distribution of Eh,i.e.the value of Eh in the Liaodong Bay tends to become lower from the northeast to the southwest.Although the organic matter is an essential factor of redox reactions,its impact on the distribution of Eh in this region is not obvious due to the higher sedimentation rate and the strong reductive environment.On the contrary,sulfide and temperature have direct impact on the value of Eh,i.e.the higher sulfide and temperature correspond to the lower Eh.Dissolved oxygen of the overlying water is another important factor,and the impact is more obvious especially in the surveyed area with relatively higher dissolved oxygen,where Eh tends to be lower with the decreasing of dissolved oxygen.In addition,the river input is also an important factor affecting the Eh,and the scope is mainly in the Fan-shaped region where fresh water can reach with the center of the Shuang Taizi river mouth.In the past two decades,the concentration of organic matter and sulfide keeps increasing due to the intensified human activity,such as land-based pollution and marine aquaculture,which results in the decreasing of Eh and significant change of the environment.In addition,the distribution and change of Eh in the surface sediments of this area should be the results of the combined effects of the long-term emissions of organic matter and sulfur,the temperature,dissolved oxygen in the overlying water and the mixing of the river input and the tide.To a certain extent,it reflects the pollution of this area.So it is necessary to take appropriate measures to strengthen environment protection in order to keep the sustainable development of the regional economy.