Comparative chemical analysis of dew and rain water

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• 作者：Imad Lekouch ; Marina Mileta ; Marc Muselli ; Irè ; ne Milimouk-Melnytchouk ; Viš ; nja Š ; ojat ; Belkacem Kabbachi ; Daniel Beysens
• 关键词：Dew chemistry ; Rain chemistry ; Water quality ; Dew water ; Atmospheric deposition
• 刊名：Atmospheric Research
• 出版年：2010
• 出版时间：February 2010
• 年：2010
• 卷：95
• 期：2-3
• 页码：224-234
• 全文大小：841 K

文摘

Dew and rain water were collected and analyzed during 3 years (2004–2006) in Zadar, Croatia. The goal was to characterize the chemical properties of dew water versus rain water (and the atmosphere in which they form) and to determine the extent to which they can be used as potable water. The corresponding parameters were measured: pH, electrical conductivity (EC), major anions (HCO₃⁻, Cl⁻, SO₄²⁻, NO₃⁻), and major cations (NH₄⁺, Na⁺, K⁺, Ca²⁺, Mg²⁺). The mean pH and EC values were comparable for both dew and rain water, pH = 6.7 (dew) and pH = 6.35 (rain), EC = 195 µS cm^− 1 (dew) and EC = 178 µS cm^− 1 (rain). The ratio (SO₄²⁻ + NO₃⁻)/(Ca²⁺ + Mg²⁺) was lower than 1, indicating the alkaline nature of both dew and rain water. Both dew and rain water exhibited low mineralization. The analysis of the major ions showed that the concentration of cations is high compared to that of anions (presumably because the NO₂⁻, HCOO⁻ and CH₃COO⁻ ions were not measured), with Ca²⁺, Na⁺ and Mg²⁺ as the main ions. In order to discriminate between the marine and non-marine origin of ions, the sea-salt fraction (SSF) was calculated by taking Na⁺ as a reference. The small SSF value in dew suggests a considerable contribution of non-marine origin for components Ca^²+, K⁺, SO₄²⁻ and NO₃⁻, except Cl⁻. In contrast, in rain water, the values of the non sea-salt fraction (NSSF) indicate that only Ca²⁺ and NO₃⁻ are not influenced by sea proximity. The study of the neutralization factor, NF, reveals the descending order of the cations in dew and rain water, NF_Ca²+ > NF_Mg²+ > NF_K+ > NF_NH4+. The dew and rain water are in conformity with the World Health Organization directives for potability, except for Mg²⁺.