胶州湾内外沉积物岩芯中多氯萘的分布特征研究

Distribution characteristics of polychlorinated naphthalenes in sediment cores inside and outside of Jiaozhou Bay

利用13C同位素稀释-高分辨率气相色谱-高分辨率质谱法测定了胶州湾内、外沉积物岩芯中多氯萘(PCNs)异构体的含量,对其同系物分布、可能来源、沉积通量及毒性当量进行了初步探讨,并研究了由各类来源PCNs进入到胶州湾的历史沉积趋势.结果表明,胶州湾内、外沉积物岩芯中∑PCNs含量范围分别为3.9～56.4pg·g-1和9.9～29.5pg·g-1(以干重计).胶州湾内、外PCNs同系物分布的共同特点是以三氯代和四氯代CNs为主,占∑PCNs的80%以上,这种同系物组成与工业制品Halowax相似.沉积物岩芯中PCNs沉积通量峰值分别出现在20世纪70年代中期(湾外)和20世纪90年代末(湾内).PCNs各异构体在沉积物垂直剖面中的含量变化表明,在20世纪50年代,PCNs主要来自木柴和煤的燃烧,在20世纪70年代至90年代初期间,有Halowax1014的输入,而垃圾焚烧飞灰的指示性单体PCN66/67和PCN52/60在岩芯上部的含量增长则表明来自城市固体废弃物焚烧的贡献越来越重要.所有样品中PCNs毒性当量含量(TEQ)都小于0.1pg·g-1(以干重计).

Concentrations of 36 congeners of polychlorinated naphthalenes （PCNs） in the sediment core collected from Qingdao coastal seas were measured using 13C isotope dilution-HRGC-HRMS.The vertical distributions,sedimentation fluxes,homologue profiles,toxic equivalents and sources of PCNs were discussed.The historical trends of contributions from different sources of PCNs in the sediments were also studied.The total PCN concentrations in the cores inside and outside Jiaozhou Bay were in the range of 3.9～56.4 pg·g-1 （dw） and 9.9～29.5 pg·g-1 （dw）,respectively.The PCNs in both the cores were dominated by tri-CNs and tetra-CNs,accounting for over 80% of the total PCNs,similar to the composition of the technical product Halowax.The maximum PCN sedimentation fluxes occurred in the mid-1970s and late-1990s inside and outside Jiaozhou Bay,respectively.The PCNs in the early years （1950s） were mainly from wood and coal burning,whereas input of Hallowax pollution to the bay during the period from 1970s to 1990s was suggested.The increase of the indicator isomers of PCNs for fly-ash in the top layers of the sediment core J37 indicates that the contribution from municipal solid waste combustion has become more important in recent years.PCN-TEQ in all of the sediments were lower than 0.1 pg·g-1,with relatively minor contribution to the total TEQs.