首页 | 本学科首页   官方微博 | 高级检索  
     


Influence of some environmental substances on atrazine adsorption in Baiyangdian lake area soil
Authors:Edward T. Urbansky  Michael R. Schock
Affiliation:1. United States Environmental Protection Agency (EPA), Office of Research and Development, National Risk Management Research Laboratory, Water Supply and Water Resources Division, Treatment Technology Evaluation Branch , Cincinnati, Ohio, 45268, USA Phone: 513–569–7655 E-mail: urbansky.edward@epa.gov;2. United States Environmental Protection Agency (EPA), Office of Research and Development, National Risk Management Research Laboratory, Water Supply and Water Resources Division, Treatment Technology Evaluation Branch , Cincinnati, Ohio, 45268, USA Phone: 513–569–7412 E-mail: schock.michael@epa.gov
Abstract:Recent reports have attempted to show that fluoridating potable water is linked to increased levels of lead(II) in the blood. We examine these claims in light of the established science and critically evaluate their significance. The completeness of hexafluoro‐silicate hydrolysis is of paramount importance in ensuring that total water quality is maintained. The possible impacts of such complexes as PbII—F—SiF5 or PbFx (2‐x) are discussed as are the contributions of fluoridation byproducts to total acid content. We calculate the fractional distribution of aqueous species based on known chemical equilibria and show the species concentrations for several different model tap waters. We discuss and quantitatively show the effects of other complexing anions, such as carbonate or hydroxide. Overall, we conclude that no credible evidence exists to show that water fluoridation has any quantitatable effects on the solubility, bioavailability, bio‐accumulation, or reactivity of lead(0) or lead(II) compounds. The governing factors are the concentrations of a number of other species, such as (bi)carbonate, hydroxide, or chloride, whose effects far exceed those of fluoride or fluorosilicates under drinking water conditions. Lastly, we consider some previous epidemiological studies of lead(II) exposure and how recent papers fare methodologically.
Keywords:Fluoridation  fluoride  fluosilicic acid  hexafluorosilicate  hexafluorosilicic acid  lead(II)  potable water  silicofluoride  water treatment
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号