北太平洋亚热带环流区表层水的^(210)Po/^(210)Pb不平衡  

^(210)Po/^(210)Pb disequilibria in the surface waters of the North Pacific Subtropical Gyre

作　　者：马嫱[1] 陈敏[1,2] 杨伟锋[1,2] 邱雨生[1,2] 黄奕普[1] 

机构地区：[1]厦门大学海洋与地球学院,福建厦门361005 [2]厦门大学近海海洋环境科学国家重点实验室,福建厦门361005

出　　处：《应用海洋学学报》2013年第1期3-12,共10页Journal of Applied Oceanography

基　　金：国家自然科学基金杰出青年基金资助项目(41125020);国家海洋局大洋专项资助项目(DY125-13-E-01);福建省自然科学基金杰出青年基金资助项目(2009J06026)

摘　　要：对北太平洋亚热带环流区表层水中溶解态(<0.2μm)和颗粒态(≥0.2μm)210Po、210Pb的含量、分布、停留时间及其在颗粒物清除迁出过程中的分馏效应开展了研究,结果表明,研究海域表层水中溶解态210Po、210Pb的比活度分别介于0.14～3.75和1.41～6.87 Bq/m3之间;颗粒态210Po、210Pb的比活度分别介于0.35～2.49和0.18～3.18 Bq/m3之间.溶解相和颗粒相中的210Po/210Pb不平衡状态呈现截然不同的特征,溶解相中210Po相对于210Pb呈亏损状态,而在颗粒相中则呈过剩状态,反映出210Po与210Pb生物地球化学行为的差异,210Po具有更强的颗粒(生物)活性.由稳态不可逆模型计算出溶解态和颗粒态210Po的平均停留时间分别为0.28、0.27 a;溶解态和颗粒态210Pb的平均停留时间分别为0.88、0.15 a.由清除速率常数法计算得到的溶解态210Po、210Pb在颗粒清除过程中的平均分馏因子为4.73,且该分馏因子随颗粒氮含量的增加呈增加的趋势.停留时间的差异以及明显大于1的分馏因子均表明,210Po、210Pb在颗粒清除过程中发生了明显的分馏,而分馏因子与颗粒氮(PN)之间存在的正相关关系则显示含氮组分对210Po、210Pb的分馏起着一定的作用.Dissolved （ 〈 0.2 μm） and particulate （≥0.2 μm） 210Po and 210Pb in surface waters collected from the North Pacific Subtropical Gyre were analyzed to understand their distribution, residence times and fractionation dur- ing particle scavenging. The activity concentrations of dissolved 210po and 210pb fell in a range of 0. 14 - 3.75 Bq/m3 and 1.41 -6.87 Bq/m3 respectively, and those of particulate 210Po and 210pb ranged from 0.35 to 2.49 Bq/m3 and from 0.18 to 3.18 Bq/m3, respectively. The disequilibria between 210po and 210pb showed different characteristics in the dissolved and the particulate phases. 210Po was deficient in the dissolved phase but excess in the particulate phase relative to 210pb, indicating their different biogeochemical behaviors and a more particulate（ or biologically） reactive 210po. The residence times of dissolved and particulate 210po estimated from an irreversible steady-state model were 0.28a and 0.27a, respectively; and those of dissolved and particulate 210pb were 0.88a and 0.15a respectively. The consistently high fractionation factors （4.73） calculated by scavenging rate constants suggested that a significant fractionation occurred between 210Po and 210pb during their scavenging from solution to particles. Furthermore, the fractionation factors increased with the increasing contents of particulate nitrogen, indi- cating that the fractionation between 210po and 210pb was influenced by N-containing components.

关 键 词：海洋化学 210Po 210Pb 北太平洋亚热带环流区 清除 分馏 

分 类 号：P734[天文地球—海洋化学]