| Autor: |
Gallagher, Patricia A.1, Schwegel, Carol A.1, Parks, Amy1, Gamble, Bryan M.1, Wymer, Larry1, Creed, John T.1 creed.jack@epa.gov |
| Předmět: |
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| Zdroj: |
Environmental Science & Technology. 5/15/2004, Vol. 38 Issue 10, p2919-2927. 9p. |
| Abstrakt: |
Seven different treatment/storage conditions were investigated for the preservation of the native As(llI)/ As(V) found in 10 drinking water supplies from across the United States. These 10 waters were chosen because they have different As(lll)/As(V) distributions; six of these waters contained enough iron to produce an iron precipitate during shipment The waters were treated and stored under specific conditions and analyzed periodically over a span of approximately 75 days. Linear least squares (LLS) was used to estimate the change in As(lll) and As(V) over the study period. Point estimates for the first and last analyses days and 95% confidence bounds were calculated from the LLS. The difference in the point estimates for the first and last day were then evaluated with respect to drinking water treatment decision making. Three primary treatments were evaluated: EDTA/AcOH- treatment and AcOH treatment as well as no treatment The effect of temperature was explored for all treatments, while the effect of aeration was evaluated for only the EDTA/AcOH treated samples. The nontreated samples experienced a 0-40% reduction in the native arsenic concentration due to the formation of Fe/As precipitates. The Fe/As precipitates were resolubilized and shown to contain elevated concentrations of As(V) relative to the native distribution. Once this Fe/As precipitate was removed from solution using a 0.45 and 0.2 ,μm filter, the resulting arsenic concentration (As(lll) + As(V)) was relatively constant (the largest LLS slope was -1.4 × 10-2 (ng As g water-1) day-1). The AcOH treatment eliminated the formation of the Fe/As precipitate observed in the nontreated samples. However, two of the AcOH water samples produced analytically significant changes in the As(lll) concentration. [ABSTRACT FROM AUTHOR] |
| Databáze: |
GreenFILE |
| Externí odkaz: |
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