黄海、渤海铅-210沉积速率的分布特征及其影响因素

Spatial variability of the ^(210)Pb sedimentation rates in the Bohai and Huanghai Seas and its influencing factors

对黄海、渤海17个箱式柱样进行了210Pb放射性活度测定,计算了近百年来210 Pb沉积速率,并结合前人资料对黄海、渤海区210Pb沉积速率的空间分布特征及其影响因素进行探讨,结果表明,黄河口附近站位沉积速率最高(>2cm/a),而在渤海中部、渤海湾以及山东半岛沿岸的站位沉积速率较小(≈0.5cm/a),部分站位沉积速率为0,表明近百年来无沉积作用或遭受侵蚀。黄海、渤海区210Pb沉积速率高值区主要分布在沿岸河口地区,如黄河口、辽河口、海河口以及朝鲜半岛西南部河流入海口等;在渤海海峡西侧存在封闭的低沉积速率区;山东半岛北岸沉积速率等值线向东北向延伸并递减,在成山头东部近海海域沉积速率最低;南黄海海域的沉积速率呈两侧高、中间低的整体态势,在南黄海西南侧沉积速率等值线则以舌状向南黄海中部延伸。在渤海南部和黄海海域,210Pb沉积速率分布模式可以直观地表征黄河入海沉积物的扩散路径和范围:黄河沉积物入海后大部分沉积在河口近海地区,少部分被沿岸流携带跨过渤海海峡向黄海输送,但其在南黄海的扩散范围可能限制在123°E以西海域,而朝鲜半岛河流沉积物的扩散范围应在125°E以东,这可能与此海区终年存在的海洋锋面作用有关。

A total of 17 box-cores,collected from the Bohai and Huanghai Seas（BHS）,were studied to investigate the sedimentation rate（SR） using the 210Pb geochronology.The results show that the SRs at the offshore of Huanghe Delta show the highest values（2 cm/a）,whereas the SRs are always lower than 0.5 cm/a in the Bohai Gulf,the central Huanghai.Combined with the previous studies,the distribution pattern of the 210Pb SR in the BHS is obtained,which is mainly controlled by the riverine sediment supply and the marine dynamics conditions.The high SRs are found in the mouths of rivers surrounding the BHS,whereas the offshore areas are characterized by the low SRs.In the northern Shandong Peninsula,the isoline of SRs extended northeastward and decreased stepwise,with the lowest SR areas located at the east Chengshantou.The SRs displayed a concave-like type in the southern Huanghai Sea（SHS）,with higher SR on both sides and lower in the central area.In the southwest SH,a ligule-like isoline of SRs extended toward the central SHS.Based on the distribution pattern of the 210Pb SR in the southern Bohai and Huanghai Seas,the dispersal pattern of the Huanghe sediments can be illustrated.Most of the Huanghe sediments were deposited within the coastal area.However,small parts of the Huanghe sediments were transported along the northern Shandong Peninsula and through the Bohai Straits into the northern Huanghai Sea.Furthermore,in the SHS,the distribution of the Huanghe sediments may be limited in the west of 123 E areas,whereas the Korean riverine sediments in the east of 125°E,which may be related to the ocean fronts in the southern Huanghai Sea.