^137Cs示踪的渤海湾黄骅港两侧海区的沉积特征

Sedimentary characteristics of the sea area on both sides of the Huanghua Harbor as traced by ^(137)Cs

取自黄骅港防波堤两侧海区的7个无扰动柱状沉积物岩心的137Cs示踪研究显示,该区137Cs曲线可以分为3种类型:①不连续的137Cs曲线(表层未检测到137Cs),②连续的137Cs曲线(表层检测到137Cs),③未检测到137Cs的曲线。137Cs示踪的沉积速率结果显示:①NE向伸展的防砂堤截断原SE向的沿岸流后,造成了黄骅港防波堤两侧近岸差异性现代沉积过程,即堤北侧距岸约4km以内海区现代沉积速为0.69～1.12cm/a,堤南侧距岸约4km处的站位8以内无沉积物沉积;②防砂堤南侧的岸外10km、水深约-4m处,存在一个速率高达1.36cm/a的现代沉积中心。上述结果与前人的工作成果对比表明,黄骅港建港前后,现代沉积速率的空间分布特征发生了明显的变化,进一步说明与人类活动密切相关的地质环境变化主导了现在的地质环境变化,应当引起人们的更多重视。

^137Cs tracing of 7 cores of undisturbed columnar sediments taken from the sea area on both sides of the seawall of Huanghua Harbor shows that there are three types of ^137Cs distribution curves： ① discontinuous curve （no ^137Cs is detected at the surface）; ② continuous curve （^137Cs is detected at the surface）; and ③ curve along which no ^137Cs is detected. Modem sedimentation rates traced by ^137Cs shows that： ① after the SE-trending coastal currents were cut off by the seawall of the NE-trending harbor, there occurred differential modem deposition on the two sides of the seawall of the harbor, i.e. the modem sedimentation rates in the sea area less than 4 km deposit near site 8 away from the shoreline on the northern side of the harbor seawall are notably higher, 0.69-1.12 cm/a, whereas no sedimentation in the sea area 4 krn away from the shoreline on the southern side of the seawall; and ② a modem depocenter with a sedimentary rates of up to 1.36 cm/a exists at -4 m water depth 10 km off the shoreline on the southern side of the seawall. A comparison between the above-mentioned results and the previous work results indicates that the geo-environmental changes closely related to human activities dominate the current geo-environmental changes, to which more attention should be paid.