| 摘要: |
| 在福建龙海九龙江口红树林省级自然保护区的林内（H样,2014年4月10日）和林外光滩（G样，2012年12月18日），各采集一根柱状沉积物；对其中的总汞、甲基汞、总汞同位素、总有机碳以及铅定年等参数进行测定.光滩柱状样长0.54 m，总沉积时间为32 a，沉积速率转折点发生在1992年左右，即该地自1992年起水文特征发生较大变化.林区柱状样的沉积受到较大干扰，无法得到准确的定年信息.光滩柱状样总汞含量范围 116.00～ 435.30 ng/g，均值为190.80 ng/g；甲基汞含量范围 0.18 ～ 0.52 ng/g，均值为0.26 ng/g.林内沉积物总汞含量范围71.75～145.50 ng/g，变化较平稳，均值为121.30 ng/g；甲基汞含量范围0.39～1.03 ng/g，均值为0.58 ng/g.总体上，林内沉积物的总汞含量比光滩低，林内甲基汞含量比光滩高.原因可能是林内微生物种群更丰富，生物活性高，有利于汞的甲基化；且林区受光照的影响较小，生成的甲基汞不易分解.两根柱状样中的汞同位素均发生了明显的负的质量分馏，光滩所受的人为源的影响更大.光致还原反应对光滩柱状样中汞同位素非质量分馏的贡献率较大.在柱状沉积物中，总汞含量与有机碳含量并无显著相关性. |
| 关键词: 海洋化学 柱状沉积物 总汞 甲基汞 总汞同位素 沉积史 |
| DOI：10.3969/J.ISSN.2095-4972.2016.01.007 |
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| 基金项目:近海海洋环境科学国家重点实验室自主课题资助项目(MELRI1202) |
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| Spaciotemporal distribution of mercury in core sediments of the mangrove ecosystem in Jiulongjiang Estuary |
| GAO Ya qin,YUAN Dong xing,LU Bing yan,SUN Lu min,LIN Hai ying,HUANG Shu yuan |
| (College of the Environment and Ecology，Xiamen University，Xiamen 361102，China;Tan Kah Kee College，Xiamen University，Zhangzhou 363105，China) |
| Abstract: |
| Levels and distributions of total mercury (THg) and methylmercury (MeHg)were studied in sediments of cores collected from inside(core H,10/4/2014) and outside(core G,18/12/2012) the mangrove forest in Longhai of Jiulongjiang Estuary. Mercury isotopes, total organic carbon(TOC) and 210 Pbex were also determined. It showed that total deposition time of bare flat(G) core （1.54 m long） was 32 years. The turning point of deposition rate occurred around 1992, suggesting that the hydrological characteristics of the site had changed since 1992. Mangrove (H)core suffered obvious interference during the deposition process which was not able for the dating of time information. In core G, concentrations of THg were in a range from 116.00 to 435.30 ng/g, with average of 190.80 ng/g, MeHg ranged from 0.18 to 0.52 ng/g with average of 0.26 ng/g. In core H, concentrations of THg were between 71.75 and 145.50 ng/g, with an average of 121.30 ng/g, MeHg were between 0.39 and 1.03 ng/g, with an average of 0.58 ng/g. Overall, THg concentration of core H was lower than that of G, while MeHg concentration of core H was higher than that of G. THg concentrations showed little change in H but greatly fluctuated in G. Negative MDF and significant MIF of odd mercury isotope were observed obviously in both cores. Core G suffered a greater impact from anthropogenic sources. The mercury MIF of G was mainly due to photoreduction reaction, while for M it might be the mix of various mechanisms. Correlation analysis showed that THg and MeHg concentrations of the cores related insignificantly with TOC. |
| Key words: marine chemistry core sediment total mercury methylmercury mercury isotope depositional history |
