Fulvlc acid

In solution buffered at pH 5, the hydrolytic half-life decreased from 12 weeks to 6 weeks as the temperature increased from 20° to 30° C, Hydrolysis at pH 7 and greater proceeded with a half-life >200 days (52). In buffered solutions and in the presence of fulvlc acid at a concentration of 0.5 mg/ml and at 25°C, the hydrolytic half-lives of atrazlne were found to Increase from 35 days to 742 days as the pH was Increased from 2.9 to 7.0 (53). However, the half-lives decreased to about 10% of those values when the fulvlc acid concentration was Increased to 5 mg/ml. 

The final two samples Investigated consisted of a marine fulvlc acid Isolated by XAD-2 resin absorption (14) of a bulk sample of near surface seawater collected from a site in the Gulf of Mexico (15) and also a soil fulvlc acid extracted from an horizon B podsol (16). These samples were dissolved In filtered Gulf Stream seawater and deionized (MllllQ) water respectively, with the addition of sufficient O.IM NaOH to effect dissolution of the solid soil fulvlc acid. 

Figure 3 also shows a comparison between the relative efficiency of riboflavin and two other natural aquatic photosensitizers, namely a soil fulvlc acid and phlorgluclnol based polymer which is believed to be an exudate of a benthic macrophyte (14), to oxidize methionine. Based on the concentration of sensitizer needed to decompose methionine at a rate of 0.03... 

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