Contribution of Municipal Effluents to Metal Fluxes in the St. Lawrence River

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• 作者：Charles Gobeil ; Bernard Rondeau ; and Luc Beaudin
• 刊名：Environmental Science & Technology
• 出版年：2005
• 出版时间：January 15, 2005
• 年：2005
• 卷：39
• 期：2
• 页码：456 - 464
• 全文大小：402K
• 年卷期：v.39,no.2(January 15, 2005)
• ISSN：1520-5851

文摘

The contribution of urban effluents to the total metalfluxes carried toward the sea by the St. Lawrence, a majorworld river, is 60% for Ag; 8-13% for Cu, Zn, Mo, Cd,and Bi; and less than 3% for all other measured elements(Al, V, Cr, Mn, Fe Co, Ni, As, Rb, Sr, Zr, Cs, Ba, W, Re,Pb, Th, U). This is inferred from measurements at the Montrealwastewater treatment plant. Except for Ag, municipaleffluents do not weigh heavily on the St. Lawrence Rivermetal budget, likely because of the physical-chemical primarytreatment applied to most effluents. Compared to directatmospheric deposition on the surface of the river, effluentswould contribute half as much Pb and one-tenth asmuch Zn. In contrast, effluents deliver twice as much Cdand six times as much Cu as the atmosphere. Stable Pbisotope ratios (²⁰⁶Pb/²⁰⁷Pb, ²⁰⁶Pb/²⁰⁸Pb) in suspendedparticulate matter from the river indicate that the total Pbcontent in the river water is three times higher than thepristine level. The ratios of Cr, Ni, Cu, Zn, and Cd to Al insuspended particulate matter are high as compared to pre-industrial sediments, which suggests that trace element fluxesare higher today. To decrease metal levels in the St.Lawrence River further will be a challenge since the sourcesof metals are not well-known.