渤海中部沉积物铅来源的同位素示踪

Tracking lead origins in the central Bohai Sea based on stable lead isotope composition

本研究对渤海中部表层和柱状沉积物中Pb的含量和同位素进行了分析,研究了其时空分布规律,并探讨了其物质来源。结果表明,表层沉积物中Pb的含量为14.54×10^-6~59.42×10^-6,其含量在渤海湾近岸、黄河口附近、研究区的东北部较高,而在研究区的中部和渤海湾北部含量较低;Pb同位素207Pb/206Pb的值为0.834 1~0.848 9,208Pb/206Pb的值为2.082 8~2.098 0。岩心沉积物中Pb含量、同位素组成与表层沉积物相似,整体上较为稳定,但在1990s以来呈现增大的趋势。渤海中部沉积物中Pb以自然来源为主,黄河沉积物是其主要物质来源,但渤海湾北端则与滦河源物质或沿岸侵蚀相关;人类活动影响主要出现在1990s以后,与中国含Pb矿石的燃烧等工业活动相关,但影响微弱,仅在黄河口西北近岸海域、渤海湾等个别站位得到体现。

The Pb concentration and stable isotopes （204 pb,206 pb,207 Pb, and 208Pb） in surface and core sediments from the central Bohai Sea have been determined to investigate their spatial/temporal distribution and sources in this area. Results showed that the contents of Pb in surface sediments varied from 14. 54 ×10^-6 to 59.42 ×10^-6 , which had higher level in the coastal Bohai Bay, nearby Huanghe River estuary and northeast of the study area. Pb isotope ratio of 207Pb/206Pb and 208Pb/206Pb varied from 0. 834 1--0. 848 9 and 2.082 8--2. 098 0 in surface sedi- ments, respectively. The core sediment records showed that Pb content and isotopic composition were similar to the surface sediments. However, the vertical values of Pb content and isotopic ratios were stable overall, but they pres- ented an increasing trend since 1990s. Pb in the central Bohai Sea sediments were mainly origined from natural ma- terials, and the Huanghe River substances was the dominated source, while the northern end of the Bohai Bay was affected by the Luanhe River or coastal erosion. The impact of human activities on the Pb deposition appeared since 1990s in the sedimentary records, which mainly referred to the combustion of Chinese leaded ores and other indus- trial activities. However, the impact was weak, only reflected on several sites in the northwest of Huanghe River mouth and Bohai Bay.