南沙群岛珊湖礁潟湖垂直沉降颗粒物中主要元素的生物地球化学过程研究
Biogeochemical process of major elements in sinking particulate of Nansha coral reef lagoons, the South China Sea
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摘要: 本文首次报道用沉积物捕捉器(ST)研究南沙群岛珊瑚礁湖沉降颗粒物中主要元素垂直通量、垂直转移形态、再循环过程及垂直通量与表层海水温度的关系.结果显示,作为生物化学沉积标志的Ca、Mg具有最高的垂直通量,达1.4和0.1g/(m2·d)以上,作为生物富集标志的Br、Ⅰ也有较高的垂直转移量;垂直转移形态的研究表明Na、K、Ca、Mg、Sr主要以碳酸盐结合态向海底转移,其中Ca、Mg、Sr占99%以上,Fe、I、Ba主要以铁锰氧化物结合态向海底输送,在垂直沉降颗粒物到达海底后,有相当部分的主要元素可再循环进入水体中,Br、I、K、Al的绝大部分进入再循环,Mg、Na、Cl有一半左右进入再循环,Ca、Sr、Ba、Fe大部分被埋葬;Na等9种元素的垂直转移量随SST呈指数降低响应,对SST的敏感性Fe >Br >Sr >Ca >Na >Cl >Mg >I >Al,这再一次验证了CaCO3随温度升高,其溶解度降低、化学沉积量增加这一自然界的普遍规律,表明在珊瑚礁海水的垂直沉降颗粒物中主要元素是作为珊瑚的重要成分与CaCO3-同被沉积下来的,CaCO3起到稀释剂的作用.Abstract: Biogeochemical process of major elements has been systematically studied in sinking particulate of Nansha coral reef lagoons,the South China Sea.The main results are as follows:The contents and vertical fluxes of major elements in Nansha coral reef lagoons were different.Vertical fluxes of most major elements in Yongshu Reef lagoon were higher than those in Zhubi Reef lagoon.Ca has the highest flux,about 1.4 g/cm2·d).Na,K,Ca,Mg and Sr were transferred onto sea floor mainly in carbonate in Yongshu Reef lagoon,Fe,I and Ba in iron-manganese oxides and Al,Br in silicate,Cl transformation tended to be in the forms of carbonate and silicate.Pdost of Br,K,A1,I in sinking particulate can recycle into seawater,half of total Mg,Na and Cl can be released into seawater.Most of Ca,Sr,Ba and Fe can be really precipitated into sediment.The order of precipitation ratio was Ca >Mg >I >Al >Br >K.Vertical fluxes of major elemenu have close relationship with SST.Na and other 8 elements decreased exponentially with SST,but K and Ba had not the relationship.The order of sensitivities to SST was Fe >Br >Sr >Ca >Na >Cl >Mg >I >Al.The vertical flux changes of Fe and Br can react SST variation.
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Key words:
- Major elements /
- sinking particulate /
- biogeochemical process /
- Nansha coral reef lagoons /
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