渤海湾西北部沿岸主要入海河流表层沉积物中无机碳形态研究

Inorganic Carbon Formation in the Surface Sediments of the Major Coastal Rivers along the North West Side of Bohai Bay

关键词:  渤海湾  表层沉积物  连续浸取  无机碳形态  河流

Key words:  Bohai Bay  surface sediment  sequential extraction  inorganic carbon fractionation  rivers

摘要:

[目的]调查渤海湾西北部沿岸河流表层沉积物中不同形态无机碳(IC)的分布和影响因素,阐明我国近岸不同环境沉积物中IC分布形态的异同和调控机制。[方法]采用连续浸取方法,根据IC在沉积物中的结合强度,将其分为交换态(氯化钠相)、弱碱结合态(氨水相)、强碱结合态(氢氧化钠相)、弱酸结合态(盐酸羟胺相)和残渣态,分析表层沉积物中不同形态的IC含量,并讨论其与各地球化学参数之间的关系。[结果]渤海湾西北部沿岸河流表层沉积物中总IC的平均含量为6.76 mg/g。沉积物中各相IC的平均含量为盐酸羟胺相(3.21 mg/g) > 残渣相(1.92 mg/g) > 氨水相(0.77 mg/g) > 氯化钠相(0.64 mg/g) > 氢氧化钠相(0.22 mg/g)。盐酸羟胺相是沉积物IC的主要形态。总有机碳(TOC)对各形态IC影响较强。氨水相IC与沉积物各参数间存在较为紧密的联系。[结论]研究区域沉积物中不同形态IC的组成和分布空间变化显著,不同地点样品中IC的活跃程度和可能的环境影响因子差异很大。

Abstract:

[Objective] The environmental behavior and mobility of inorganic carbon (IC) depend strongly on their specific chemical forms and binding state. This study investigated the specific chemical forms of IC in the surface sediments collected from the coastal rivers along the Bohai Bay.[Methods] Sediment samples were extracted sequentially using solutions of sodium chloride (NaCl),ammonia (NH₃·H₂O),sodium hydroxide (NaOH),hydroxylamine hydrochloride (NH₂OH·HCl),resulting in five fractions:Exchangeable fraction (NaCl fraction),weak alkali extractable fraction (NH₃·H₂O fraction),strong alkali extractable fraction (NaOH fraction),weak acid extractable fraction (NH₂OH·HCl fraction) and residual fraction. Geochemical factors affecting the IC content were discussed.[Results] The average IC content in surface sediments of the coastal rivers along the Bohai Bay was 6.76 mg/g. The average content of IC in different fractions was NH₂OH·HCl fraction (3.21 mg/g) > residual fraction (1.92 mg/g) > NH₃·H₂O fraction (0.77 mg/g) > NaCl fraction (0.64 mg/g) > NaOH fraction (0.22 mg/g).NH₂OH·HCl fraction was the main speciation of IC in sediments. Total organic carbon (TOC) had a strong impact on various IC fractions. The IC content extracted by NH₃·H₂O was closely related to sediment parameters.[Conclusion] The composition and distribution of different forms of inorganic carbon in the surface sediments of the studied area exhibited a significant spatial variation. In addition, a significant difference was found in the mobility of IC and the possible environmental parameters in the sediments from different sampling site.