Zinc Speciation in the Suspended Particulate Matter of an Urban River (Orge, France): Influence of Seasonality and Urbanization Gradient

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• 作者：Pierre Le Pape ; C茅cile Quantin ; Guillaume Morin ; Delphine Jouvin ; Isabelle Kieffer ; Olivier Proux ; Jaafar Ghanbaja ; Sophie Ayrault
• 刊名：Environmental Science & Technology
• 出版年：2014
• 出版时间：October 21, 2014
• 年：2014
• 卷：48
• 期：20
• 页码：11901-11909
• 全文大小：365K
• ISSN：1520-5851

文摘

Among trace metal pollutants, zinc is the major one in the rivers from the Paris urban area, such as the Orge River, where Zn concentration in the suspended particulate matter (SPM) can reach 2000 mg/kg in the most urbanized areas. In order to better understand Zn cycling in such urban rivers, we have determined Zn speciation in SPM as a function of both the seasonal water flow variations and the urbanization gradient along the Orge River. Using TEM/SEM-EDX and linear combination fitting (LCF) of EXAFS data at the Zn K-edge, we show that Zn mainly occurs as tetrahedrally coordinated Zn²⁺ sorbed to ferrihydrite (37鈥?6%), calcite (0鈥?7%), amorphous SiO₂ (0鈥?1%), and organic-P (0鈥?0%) and as octahedrally coordinated Zn²⁺ in the octahedral layer of phyllosilicates (18鈥?5%). Moreover, the Zn speciation pattern depends on the river flow rate. At low water flow, Zn speciation changes along the urbanization gradient: geogenic forms of Zn inherited from soil erosion decrease relative to Zn bound to organic鈥損hosphates and amorphous SiO₂. At high water flow, Zn speciation is dominated by soil-borne forms of Zn regardless the degree of urbanization, indicating that erosion of Zn-bearing minerals dominates the Zn contribution to SPM under such conditions.