1725SAMPLEEXAMSSOLUTIONS

1725SAMPLEEXAMSSOLUTIONS - 1.725 Chemical Fate and...

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Unformatted text preview: 1.725 Chemical Fate and Transport Quiz #1 Friday, 10 October, 2003 Q20 pntS ecI') 1) At an experimental watershed, you have received permission to carry out experiments in which small amounts of several radionuclides are introduced into a small river as tracers. In one experiment you introduce an 85 mCi pulse of arsenic-76 (t 1 / 2 =26.4h) in the chemical form of sodium arsenate into the river. Flow at the time is 2.7 m 3 /s, and the relatively uniform but winding natural channel has a cross-section of 19 m 2 and average depth of 1.2 meters. u* is 0.3 m/sec. a) Estimate a longitudinal dispersion coefficient for this river. b) Determine the distance from injection point to point of maximum concentration of arsenic-76, as well as spatial standard deviation of the radionuclide, 8 hours after the spill. c) What is the activity of the radionuclide at this time and location (expressed as mCi/L), assuming no sorption occurs?-' A d -1 \ -f d \.1m. \I ZaS = OA*2rfI\S- O'\\ (o.\S~m~s rr\~,~'sm~LC\.2'5O bo di6;act= 'e\ovt * tine b) 6%&-%n t ; X t 0 I M-t O 'o9 r = Gklrn , %Nlr i & EtS Z E om rs vm a-w EE e~ 2~.ts 6- JlTO;S~r~s^ -s M \= -mo6% , S.oI I\m areo- \ \OL \L. : kn2- b OU -%-'\; -. 4.q _n t'\J 1. o-2AJ =L\IA~ e- O.OLu JW' QhI) ,ant \ 'oo L S 's. I b}s. I - rL.\ mC'L C) CXZ) qr-Y''to t 6 P_('*It e t _\L ty~~% S. soec(L~t e 36.mt 0~ M V~ n cwr a 0 nu ' = \4t (t, L \' cc,t') Y qAIM(:%JMI WNs %oAsc - jou bd t *eo Q* th o 0f% cX' C tteitQd YV o Coentio), on6 tht 'nQa n'tt nt jar 6stvc" \ s Wt\k 'c C o c-tVt decol, SnXt 't;S'on cues tre tue to qred out, -Ve mo4mumn acti'r decrees Wt tmn etV Xr rs:o decwj. Cm-- 't eCo W t Cxi tclat as t; ctreaies, mtnWt 6tcrtes,. 2 (o66f\0noA) or nVco8nW\ing 'at OU Wt-tre aked lkr _'t\L, a- '%ytlirutc\u) ng 4bAtmt SOyntiDW . . . . . .~ ~ ~ ~ ~ ~ ~ ~ - I 2) Several large tanks of water are to be adjusted to different pH values in order to test fish survival under conditions of acidification. Well water with an initial Alk of 6 x 10-4 eq/L and pH of 6.5 is pumped into open storage tanks and amended with H 2 SO 4 to make waters having pH values of 6.0, 5.0, and 4.0, respectively. a) How much H 2 CO 3 * is initially present in the well water? b) How much sulfuric acid (in equivalents/L) must be added to the well water to adjust it to pH 6.0? c) A day after the storage tanks are filled and adjusted to their correct pH, it is found that the pH 6 tank has risen to pH 6.5! How could this happen, if nobody has made any further additions of chemicals to the tanks? Sups- ~ a-) hfOn ejtCS 6r-an wW ' 4- (A WY %, %tt _ C 4 , 5 V w) i'Ct - C t tz. ,t c-r r ' - C'tr Ctun nyt\-etCt tCo' ,s t s ttYW . t - ~-F or c 5 W. b) S e C-7 N\L- 3\o- el A.Vh\naS 64crea0td b t\\o e csw SYct O\ ngI R\VsU \`4 e L 5 th. c) kt wter n\Ait 'naue'o bn ours~tuate\ \x \u\ tws so sornre *t C-L \-AQ\A\nd t es\tNaeq Iq t b rnt 0N, YC)q\ h WOA\t \%qr C , Vnct \ dotsyn cnat no fro Y9 0C% 6 s r DCLs Ot '%n,\4\ct6 we & kt te dsgwn C tt 6\8 wmu\m vcrea . 3) A pond has depth d (cm) and area A. Propane gas is added as tracer; propane is3) A pond has depth d (cm) and area A....
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This note was uploaded on 11/21/2009 for the course CEE 432 taught by Professor Ahmed during the Spring '09 term at Rowan.

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1725SAMPLEEXAMSSOLUTIONS - 1.725 Chemical Fate and...

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