兴化湾西岸潮间带沉积物岩心放射性核素分布与沉积速率  

The distributions of radionuclides in a sediment core and sedimentary rate in the intertidal zone of Xinghuawan Bay

作　　者：纪丽红[1] 李超[1] 刘广山[1] 

机构地区：[1]厦门大学海洋系,福建厦门361005

出　　处：《海洋学研究》2009年第3期1-7,共7页Journal of Marine Sciences

基　　金：国家自然科学基金资助项目(40306018)

摘　　要：利用2007年8月31日采集于福建兴化湾西岸的潮间带沉积物岩心样品，用γ谱方法测量了其放射性核素含量，对岩心中核素的分布及其成因进行了讨论，估算了研究区沉积物的沉积速率，探讨了沉积物的物源，结果表明：（1）^238U、^228Th、^228Ra、^226Ra、^210Pb、^137Cs和^40K的含量分别为35．0～60．6、52．6～69．3、49．0466．5、22．7～36．2、26．3～84．8、0．5～1．3和775～831 Bq／kg；（2）用^238U、^226Ra、^137Cs和^40K作为示踪剂进行物源分析发现，兴化湾潮间带沉积物主要源于邻近的福州和莆田地区的土壤，所占比率分别为54％和46％；（3）用^210Pbex和^137Cs方法估算得兴化湾西岸潮间带沉积物的平均沉积速率分别为0．38cm／a和0．36cm／a。岩心中^210Pbex分布表明，自20世纪末，研究区潮间带沉积速率加快。One sediment core was collected from intertidal zone located west coast of Xinghuawan Bay, Fujian, China. The radionuclide contents in the cores were measured by γ spectrometry and the vertical distributions of the nuclides were discussed. The sources of sediment were evaluated using 23^238U, ^226Ra, ^137Cs and ^40K as tracers. The sedimentary rate was estimated by ^210Pbex and ^137Cs methods. The detectable nuclides in this core are ^238U, ^228Th, ^228Ra, ^22GRa, ^210pb, ^137Cs and ^40K. The contents of these nuclides are 35.0-60.6, 52.6-69.3, 49.0-66.5, 22.7-36.2, 26.3-84.8, 0.5-1.3 and 775-831 Bq/kg, and with the averages of 45.4, 61.2, 61.2, 31.4, 45.6, 0.9 and 804 Bq/kg respectively. The ^238U activities in the 0 - 40 cm zone contents were found in the depth of 50-60 cm were comparable within the measuring error and high ^238U and below which ^238U activities fluctuate with no trend. With the similar trend, from surface to 22 cm depth the activities of ^228Th and ^228Ra are lower and increase slowly with increasing depth, and they are consistent within the error. Throughout the entire core length the ^228Ra and ^228Th is decay equilibrium. ^226Ra activities increase with increasing depth from surface to 22 cm depth, and the contents comparable from 22 cm to 72 cm, occurring fluctuation deeper than 72 cm. The ^210Pb activities decrease exponentially both from surface to 12 cm and in the zone of 16-40 cm, but below the depth of 40 cm ^210Pb is decay equilibrium with 26Ra. The distribution has a maximum activity at the depth of 16 cm, above which the ^137Cs contents are uniform distribution through consistent within measuring error but below which decrease with depth. ^10K is entire length of the core. The sedimentation sources of Xinghuawan Bay are mainly from the surface soil of Fuzhou and Putian Prefectures surrounding it. Using ^238U, ^226Ra, ^137 Cs and ^40K as tracer, by the content data of these four nuclides in the sediments contributions of the soils natural radionuclides can measured in this stu

关 键 词：潮间带 沉积物岩心 放射性核素 沉积速率 兴化湾 

分 类 号：P736.2[天文地球—海洋地质] P736.4[天文地球—海洋科学]