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z <br /> •- the percent change in measured concentration over the test duration For TBA, if a <br /> peak concentration was noted, the percentage is calculated from the peak level, not <br /> the initial level <br /> Each time series of data includes an observed lag time, or acclimation time, prior to an <br /> observed decrease in monitored concentration levels (if any) The range of acclimation <br /> time is noted 1n the summary tables of Appendix 2 For TBA where an intermediate <br /> increase in TBA concentration is noted, the noted lag time is of longer duration than the <br /> peak time <br /> Conservation equations are used in estimating degradation rates from the microcosm data <br /> results, consistent with DeVaull, G E , et al , 1997 For each microcosm, we fit an overall <br /> observed rate parameters to the active period of decrease in monitored concentration <br /> Presuming zero-order kinetics (concentration change independent of concentration), <br /> FA <br /> — V dt <br /> ri <br /> or, given data at specific time increments, tf 1a1nd tz, <br /> Y eff �Cw r 2 —Cw a I) <br /> Aw,—observedi_Z <br /> — Vw (t2 —t!) <br /> Presuming first-order kinetics (concentration change linearly dependent on <br /> concentration), <br /> k _ A" Veff 1 dew, _ Veff dln(cw,) <br /> w` 0w, Vw cw dt V. dt <br /> or, given data at specific time increments, <br /> kw r—observedi_Z M <br /> Veff ll! Gw e 2 —In Cw, I <br /> V (t2 —t,) <br /> In the above equations, <br /> Aw,_,,bse,.,,ed[mg/(hr-L-water)] observed maximum rate constant for chemical i <br /> kw,obse,,,ed(I/hr) observed first-order rate constant for chemical 1 <br /> cw, (mg/L-water) water-phase chemical concentration <br /> t (hr) elapsed time <br /> and <br /> VQ ff =V+V H, +ms fog Kpe, <br /> with <br /> 15 <br />