摘要
选取辽河口海岸带沉积物作为研究对象,通过测定沉积物中^(137)Cs比活度,来分析沉积物中^(137)Cs比活度、蓄积总量的分布特征及影响因素,并基于^(137)Cs的测年原理估算该区域的沉积速率。结果表明:辽河口海岸带表层沉积物中^(137)Cs比活度的变化范围为(1.03±1.01)～(15.68±1.13)Bq/kg,平均值为5.09±0.34Bq/kg(n=17),变化幅度较大;在空间上呈现出由陆地向潮滩、由西向东逐渐降低的趋势。该区域沉积物柱样中^(137)Cs比活度的垂直分布主要呈现出单峰型、双峰型和不规则曲线的分布态势。采用^(137)Cs起始层位法与最大峰值法计算辽河口海岸带沉积物的沉积速率,均发现辽河口海岸带沉积物的沉积速率呈现出从北到南(从陆地到海洋)逐渐增大的趋势。沉积物中^(137)Cs蓄积总量范围为(980±46)～(6094±92)Bq/m2,平均值为2278±42Bq/m2,高于研究区^(137)Cs的全球大气沉降通量值1310Bq/m2(衰变校正到2015年);全球大气沉降的^(137)Cs约占该区域^(137)Cs蓄积总量约57.5%,表明该区域沉积物中^(137)Cs的主要来源是全球大气直接沉降。
137Cs activities are measured for the 17 sediment cores collected from the coastal zones of the Liao River in order to disclose the distribution patterns and geochemical behaviors of 137Cs.It is found that 137Cs activity concentrations in the surface sediments vary in a significant spatial range from1.03±1.01 to 15.68±1.13 mBq/g around an average of 6.727±0.251 mBq/g(1σ)attributing to the changes in vegetation types.Highest 137Cs activity concentration(15.686±1.131 mBq/g)is observed in the sediment core of Z-9 where reeds predominate natural vegetation and human activity is rare.The vertical distribution pattern of 137Cs activity concentrations falls into three categories,one-peak curve,two-peak curve and irregular curve.For the two-peak curves of 137Cs activity concentration,there is a sub-peak of 137Cs activity concentration in the sediment profiles except the maximum of 137Cs.As to the irregular curves of 137Cs(LH-15,LH-18),the 137Cs activity concentrations decreases from the sub-layer to the bottom and part of the surface sediment was missing,or for another possibility bottom sediment was putting on the surface layer by anthropogenic activities Sedimentation rates are calculated with the initial 137Cs appearance value(1954)up to the maximum value(1963)of the sediment cores.The average value of sedimentation rates(0.48 to 1.63 cm/a)deduced from137Cs maximum value seem to be lower than the rates(0.51 to 1.77 cm/a)calculated from137Cs initial appearance.The 137Cs inventories vary from980±46 to 6094±92 Bq/m2,with an average of2278±42 Bq/m2.Furthermore,the average 137Cs inventories of the study are higher than the global fallout flux 1310 Bq/m2(137Cs activity was decay corrected to 2015).This result clearly indicates that the 137Cs atmospheric precipitation is the main source of 137Cs in the region of Liao River Estuary.
作者
张克新
潘少明
刘志勇
李国胜
ZHANG Kexin;PAN Shaoming;LIU Zhiyong;LI Guosheng(College of Environmental Science and Engineering,Yangzhou University,Yangzhou225127,China;Yangzhou Hongshuo Environmental and Biological Engineering Research Co.Ltd.,Yangzhou225127,China;Key Laboratory of Coast and Island Development of Ministry of Education,Nanjing University,Nanjing 210023,China;School of Radiation Medicine and Protection,Soochow University,Suzhou215123,China;Institute of Geographic Sciences and Natural Resources Research,CAS,Beijing 100101,China)
出处
《海洋地质与第四纪地质》
CAS
CSCD
北大核心
2019年第1期91-99,共9页
Marine Geology & Quaternary Geology
基金
国家自然科学基金项目"渤海钚(Pu)同位素的来源及其示踪应用研究"(41671466)
江苏省自然科学基金项目"江苏海岸带多环境介质中Pu与137Cs的迁移路径与示踪研究"(BK20171292)
关键词
137Cs活度浓度
沉积物
分布特征
沉积速率
辽河口
137Cs activity concentration
sedimentation rate
distribution characteristics
Liao River Estuary
