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【目的】探寻北部湾湾口海槽重金属的分布、联系、积累及其与气候关系。【方法】在北部湾南部海槽处钻取200cm长度岩芯并垂直分样,再进行典型重金属(Pb、Cr、Zn等)、微量元素、粒度、矿物测试、14C定年综合测试及其处理分析。【结果】岩芯沉积物和重金属具有陆源性,化学蚀变指标CIA显示出气候波动变化:总体上气候趋向暖湿,陆源供给加大,可分为两个基本气候阶段。重金属和细粒级对气候变化响应明显,其含量、分配均随深度变浅,即随气候演进而呈增加趋势;岩芯沉积物组分以悬移质为主,与海水悬移质粒级有对应性;重金属来自吸附与再沉积,6~9φ为吸附粒级。自50 cm以来重金属积累系数fe变化曲线(采用动态计算本底值的方法)显示,重金属自25 cm以来积累加快,结合趋势相对斜率,Pb具有明显增加且分化明显的特征。【结论】以上重金属含量变化是对气候变化的响应。
【Objective】 The purpose of this study is to explore the distribution, correlation and accumulation of heavy metals in Beikoukou Bay of Beibu Gulf and its relationship with climate. 【Method】 A 200 cm long core was drilled at the southern trough of Beibu Gulf and vertically divided into samples. Typical heavy metals (Pb, Cr, Zn, etc.), trace elements, grain size, minerals, 14C dating and their processing were analyzed . 【Result】 The core sediments and heavy metals are terrigenous. The chemical alteration indicator CIA shows the variation of climate. Generally speaking, the climate tends to warm and wet, and the supply of terrestrial sources increases. It can be divided into two basic climatic stages. Heavy metals and fine-grained response to climate change significantly, its content and distribution are shallow with depth, that is, with the evolution of the climate showed an upward trend; core sediment components to suspended matter-based, Correspondence; heavy metals from adsorption and re-deposition, 6 ~ 9φ adsorption particle size. The heavy metal accumulation coefficient (FE) since 50 cm (using the method of dynamic calculation of background value) shows that the accumulation of heavy metals has accelerated since 25 cm, and the Pb has obvious increase and obvious differentiation in combination with the relative slope of the trend. 【Conclusion】 The above changes in heavy metal content are responses to climate change.