摘要
河流溶解硅(DSi)承载着陆地表生过程的环境信息,其输入、迁移、转化和输出受多种因素制约。在全球硅酸盐岩风化过程中,31.53%~64.87%的DSi被陆地植被吸收,仅12.91%迁移至河流,在向海洋输送过程中,河流DSi又受到水生生物吸收、逆风化作用及"人造湖效应"等因素的影响,输出量进一步减少,弱化了海洋系统的"生物泵"作用;不多的研究表明全球河流DSi浓度变化介于138~218μmol/L之间,空间差异显著,有必要量化各影响因素的贡献,建立多因素控制的河流DSi输出通量模型;与地壳主要硅酸盐岩的δ^(30)Si值(约为-0.5‰)相比,全球河流DSi的δ^(30)Si值变化范围较大(介于-0.2‰~3.4‰之间)且显著正偏,分馏系数达0.3%~3.9‰。这是由于流域内Si同位素的无机分馏和有机分馏2种动力分馏过程所导致。因此,探讨河流DSi来源、迁移及转化机制是未来深入研究河流DSi循环的关键问题。
The riverine dissolved silicon（DSi） brings environmental information on biogeochemical processes of terrestrial surface,of which the input,transferring,transformation and output are influenced by many factors.Among the weathering of global silicate rocks,31.53%-64.87%of DSi are intercepted by terrestrial vegetation and only about 12.9%are transferred into rivers.During being transported into ocean,riverine DSi gets impacts from aquatic biological absorption,reverse weathering process and artificial lake effect.The quantity of output is further reduced,which weakens the effect of the oceanic biological pump.According to limited data,the DSi concentration of global rivers has a large variation,ranging from 138 μmol/L to 218 μmol/L.It is necessary to quantify contribution rates of influencing factors and establish output models controlled by multiple factors.The δ^30 Si of riverine DSi ranges from —0.2‰ to 3.4‰.Comparing with the δ^30 Si of silicate rock,which is about —0.5‰,the fractionation factor is significantly partial to positive from 0.3‰ to 3.9‰.That is because of the occurrence of kinetic fractionation process in river basin including inorganic and organic fractionation.Thus,the key problems,sources and transformation mechanisms of riverine DSi during migration and being transported should be solved in future.
出处
《地球科学进展》
CAS
CSCD
北大核心
2015年第1期50-59,共10页
Advances in Earth Science
基金
国家自然科学基金项目“海南岛典型流域生态系统硅的生物地球化学循环研究”(编号:41340019)
“人类活动干预下的流域地表过程在河流碳循环中的响应”(编号:41071054)资助
关键词
河流溶解硅
硅稳定同位素组成
硅循环
化学风化
Riverine dissolved silicon
Silicon stable isotopic composition
Silicon cycle
Chemical weathering.
