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| | =Can one use plant material to measure the provenance of selenium?= | | =Can one use plant material to measure the provenance of selenium?= |
| | | | |
| − | =Can one perform PAA measurements of Se-82 and Se-76?=
| + | [[Se_Overview_PrevMeas]] |
| | | | |
| | + | As shown in the Figure below, the Se-82/Se-76 ratio varies from -1.2% to +0.2% for plant materials but remains relatively constant for other materials. The variations in plant material has been described as being due to differences in the bacteria residing in the plant. The question to investigate is whether or not these variations in the concentration can be used to determine the provenance of the sample. |
| | | | |
| − | ==Neutron knockout of Se-82==
| |
| − | If you knock a neutron out of Se-82 you produce the unstable isotope Se-81 which Beta emitts with half life of 18 min and a meta-state that emmits a 103 keV gamma with a 57 minute half life.
| |
| | | | |
| − | <math>{82 \atop 34\; }Se (\gamma,n){81 \atop \; }Se</math>
| |
| | | | |
| − | Other prominent photons
| |
| | | | |
| − | 260 & 276 keV for the 57 minute half life isotope
| + | [[File:Krouse_Fig_1.png | 200 px]] |
| | | | |
| − | ==Neutron knockout of Se-76== | + | == Below is a table listing the natural abundances of Selenium== |
| − | If you knock a neutron out of Se-76 you produce the unstable isotope Se-75 which has a half life of 119 days.
| + | Natural abundance of selenium |
| | | | |
| − | <math>{76 \atop\; }Se (\gamma,n){75 \atop \; }Se</math>
| + | {| border="3" cellpadding="5" cellspacing="0" |
| − | | + | | Isotope|| Abundance |
| − | The prominent photons emitted have the following energies
| |
| − | | |
| − | 136, 264, and 279 keV
| |
| − | | |
| − | | |
| − | The article below describes how plant material and soil contain Se-76 to Se-82 ratios that differ from other natural samples by 1.5%. They argue that it is due to the bacteria living in plant material.
| |
| − | | |
| − | [[File:Krouse_CanJournChem_40_1962_p367.pdf]]
| |
| − | | |
| − | Plant material is a natural way to sample the selenium content to determine if there are difference isotopic ratios due to the impact of human activities on the environment.
| |
| − | | |
| − | =Experiments=
| |
| − | | |
| − | ==Chlorine==
| |
| − | | |
| − | It looks like Cl-35 is abundant as you see photon energies of 146 keV and 2127 keV (you can barely see 1176 keV) from Cl-34's decay (neutron knocked out of Cl-35).
| |
| − | | |
| − | The half life is 32 minutes.
| |
| − | | |
| − | Should check the half life from the run AccOnAlInDetASe-AinDetD_001.root using the calibration
| |
| − | | |
| − | MPA->Draw("0.18063+0.960133*evt.Chan>> SeRun_008(8000,0.5,8000.5)","evt.ADCid==3"); | |
| − | | |
| − | == Irradiation of Horse Mineral Supplement==
| |
| − | | |
| − | === Chlorine is a dominant signal===
| |
| − | | |
| − | | |
| − | First, look at the peak around 146 keV
| |
| − | [[File:146_keV.png | 200 px]]
| |
| − | | |
| − | Next I plotted the counts as a function of time to get an exponentially decaying graph. When doing an exponential fit here, the parameter "b" given by root will be the decay constant.
| |
| − | | |
| − | [[File:Counts_vs_time_146kev.png | 200 px]]
| |
| − | | |
| − | Root gives a value b = 3.83655x10^-4, which yields a half life of 30.11 minutes.
| |
| − | | |
| − | | |
| − | Now do the same for the 2127 keV line
| |
| − | [[File:2127_keV.png | 200 px]]
| |
| − | | |
| − | Here are the counts plotted as a function of time
| |
| − | [[File:Counts_vs_time_2127keV.png | 200 px ]]
| |
| − | | |
| − | Root gives b = 3.31508x10^-4, which yields a half life of 34.8 minutes.
| |
| − | | |
| − | | |
| − | === Potassium is a potential signal ===
| |
| − | | |
| − | Looking at the spectrum for the fast irradiation sample, there are 2 prominent lines that could be from 38-K. The mechanism would be a single neutron knockout from a stable 39-K nucleus. The two most dominant energies of the three for 38-K are 2167 keV and 3936 keV and the half life is 7.63 minutes. Below is a fit to the energy spectrum histogram
| |
| − | | |
| − | [[File:2168_peak.png | 200 px]]
| |
| − | | |
| − | Now check the half life
| |
| − | | |
| − | | |
| − | [[File:2168keV_halflife.png | 200 px]]
| |
| − | | |
| − | Root gives a value for b = -1.44513x10^(-3), which in turn gives a half life of 8 minutes
| |
| − | | |
| − | Next check the 3936 peak
| |
| − | | |
| − | [[File: 3937_Peak.png | 200 px ]]
| |
| − | | |
| − | and check the half life
| |
| − | | |
| − | [[File: 3937_halflife.png | 200 px ]]
| |
| − | | |
| − | Root gives a value for b = - 1.52044x10^(-3), which in turn gives a half life of 7.6 minutes
| |
| − | | |
| − | It seems very possible that 38-K could be in the sample of horse feed.
| |
| − | | |
| − | ===Possible Yb-167 in the Sample===
| |
| − | | |
| − | Yb-167 has a half life of 17.5 minutes and can be produced by knocking a neutron out of Yb-168, which is stable.
| |
| − | | |
| − | I looked at the horse feed spectrum and compared the spectral lines for Yb-167, below is a table of those results:
| |
| − | | |
| − | | |
| − | | |
| − | {| border="3" cellpadding="5" cellspacing="0" | |
| − | | Energy (keV) || Spectrum Energy (keV) || Half life (min) | |
| | |- | | |- |
| − | | 90.84 || 89 || 18.23 | + | | Se-74 || 0.86% |
| | |- | | |- |
| − | | 106.18 || 105 || 18.0 | + | | Se-76 || 9.23% |
| | |- | | |- |
| − | | 112.88 || 113 || 18.86 | + | | Se-77 || 7.60% |
| | |- | | |- |
| − | | 132.02 || 137 || 19.2 | + | | Se-78 || 23.69% |
| | |- | | |- |
| − | | 161.29 || 161 || 17.3 | + | | Se-80 || 49.80% |
| | |- | | |- |
| − | | 203.75 || 204 || 17.27 | + | | Se-82 || 8.82% |
| − | |- | + | |} |
| − | | 280.5 || 281 || 17.0 | + | |
| | + | == Below are possible PAA reactions that may be used to observe specific Se isotopes== |
| | + | |
| | + | {| border="3" cellpadding="5" cellspacing="0" |
| | + | | Reaction|| Half-life ||Relative activity ||Gamma-rays, keV (BR) |
| | |- | | |- |
| − | | 290.89|| 289 || 16.7 | + | | Se-74(gamma,n)Se-73 || 7.1 h || 1.5E-1 || 361 (100) |
| | |- | | |- |
| − | | 323.5|| 322 || 16.6 | + | | Se-74(gamma,n)Se-73m || 39 m || 3.2 || 402 (4) |
| | |- | | |- |
| − | | 354.0 || 354|| 16.7 | + | | Se-74(gamma,np)As-72 || 26 h || 1.0E-3 || 834 (100) |
| | |- | | |- |
| − | | 375.9 || 378|| 15.5 | + | | Se-76(gamma,n)Se-75 || 120 d || 1.3E-2 || 265(29) |
| | |- | | |- |
| − | | 387.0 || 388.4|| 19.1 | + | | Se-77(gamma,p)As-76 || 26.4 h || 4.4E-2 || 559(44) |
| | |- | | |- |
| − | | 398.1 || 402|| 16.1 | + | | Se-78(gamma,p)As-77 || 38.8 h || 8.6E-2 || 239(2) |
| | |- | | |- |
| − | |688.5 || 691 || 15.6 | + | | Se-80(gamma,n)Se-79m || 3.9 m || 5.9 || 96(10) |
| | |- | | |- |
| − | |733.2 || 736 || 17.1 | + | | Se-80(gamma,np)As-78 || 1.5 h || 2.2E-2 || 614(54) |
| | |- | | |- |
| − | |920.32 || 922 || 16.6 | + | | Se-80(gamma,p)As-79 || 8.2 m || 1.3 || 96(9) |
| | |- | | |- |
| − | |977.9 || 980 || 16.9 | + | | Se-80(gamma,<math>a</math>p)Ge-75 || 83 m || 2.8E-1 || 265(11) |
| − | |-
| |
| − | |1025.9 || 1028 || 16.9
| |
| − | |-
| |
| − | |1242 || 1245 || 17.5
| |
| − | |-
| |
| − | |1340.1 || 1341 || 16.5
| |
| − | |-
| |
| − | |1410.4 || 1413 || 18.6
| |
| − | |-
| |
| − | |1433.4 || 1437 || 16
| |
| − | |-
| |
| − | |1631.7 || 1630 || 19.6
| |
| | |- | | |- |
| | |} | | |} |
| | | | |
| − | The average of these half lives is 17.22 minutes, but it turns out this was just coincidental noise meaning we must overbin the spectrum.
| + | =Can one perform PAA measurements of Se-82 and Se-76?= |
| | | | |
| − | ===Investigation of Se_B_002===
| + | [[Se_PAA_Reactions]] |
| − | | |
| − | Using the Se_B_002, I will investigate the peaks seen in the spectrum.
| |
| − | | |
| − | The first peak seen in the spectrum was at 74.1 \%pm%\ 2.947 keV. The half life was found to be 324.94 days. When doing the rad search I used a window from 69-79 keV and a half life window from 200-400 days.
| |
| | | | |
| | + | =Experiments= |
| | | | |
| − | {| border="3" cellpadding="5" cellspacing="0"
| + | ==[[PAA_Selenium_ActivityCalc]]== |
| − | | Isotope || Energy (keV) || I(%) || Half life
| |
| − | |-
| |
| − | | 153-Gd || 69.67 ||2.419 || 240 days
| |
| − | |-
| |
| − | | 254-Es || 69.7 || not given || 275.7 days
| |
| − | |-
| |
| − | | 254-Es || 70.4 || not given || 275.7 days
| |
| − | |-
| |
| − | | 153-Gd || 75.4 || 0.0783 || 240.4 days
| |
| − | |-
| |
| − | |}
| |
| − |
| |
| − | 254-Es doesn't really have a mechanism to produce this isotope. The nearest stable isotope would have to have greater than a quadruple neutron knockout, or a triple proton knockout.
| |
| | | | |
| − | 153-Gd could possibly be produce from 154-Gd by knocking out a neutron, but the half life is still far off. The hottest decay lines for 153-Gd are 97.4 and 103.2 keV with I = 29 and I = 21.11 respectively. Neither of these lines are seen in the spectrum so it is unlikely that it is either of these isotopes.
| + | [[PAA Selenium/Soil Experiments]] |
| | | | |
| | + | [[LB Se PAA Horse Feed Experiment]] |
| | | | |
| | + | ==Background Signals== |
| | + | [[PAA_BackGrd_Det_A]] |
| | | | |
| − | | + | ==Nickel Normalization== |
| − | | + | [[LB PAA Nickel Investigation]] |
| − | The next clear peak is seen at 85.5 \%pm%\ 3.89 keV. The half life was found to be 99.1 days. When doing the rad search I set a range of energies from 75-95 keV with a half life range from 50-150 days. The possible isotope information is below
| |
| − | | |
| − | {| border="3" cellpadding="5" cellspacing="0"
| |
| − | | Isotope || Energy (keV) || Ig(%) || Half life
| |
| − | |-
| |
| − | | 257-Fm || 75.0 ||0.200 || 100.5 days
| |
| − | |-
| |
| − | | 174m-Lu || 76.47 || 0.0638 || 142 days
| |
| − | |-
| |
| − | | 170-Tm || 78.63 || 0.00347 || 128.6 days
| |
| − | |-
| |
| − | | 159-Dy || 79.45 || 0.00048 || 144.4 days
| |
| − | |-
| |
| − | | 168-Tm || 79.804 || 10.53 || 93.1 days
| |
| − | |-
| |
| − | |258-Md || 80.1 || 2.43 || 51.5 days
| |
| − | |-
| |
| − | |257-Fm || 80.2 || 0.085 || 100.5 days
| |
| − | |-
| |
| − | |75-Se || 80.94 || 0.0077 || 119.779 days
| |
| − | |-
| |
| − | |183-Re || 82.9182 || 0.294 || 70.0 days
| |
| − | |-
| |
| − | |170-Tm || 85.25474 || 2.5 || 128.6 days
| |
| − | |-
| |
| − | |182-Ta || 84.6802 || 2.65 || 114.43 days
| |
| − | |-
| |
| − | |183-Re || 84.7125 || 0.97 || 70.0 days
| |
| − | |-
| |
| − | |188-W || 85.32 || 0.0024 || 69.4 days
| |
| − | |-
| |
| − | |160-Tb || 86.7882 || 13.15 || 72.3 days
| |
| − | |-
| |
| − | |258-Md || 86.9 || 0.5615 || 51.5 days
| |
| − | |-
| |
| − | |168-Tm || 87.73 || 0.000016 || 93.1 days
| |
| − | |-
| |
| − | |127m-Te || 88.26 || 0.084 || 109 days
| |
| − | |-
| |
| − | |123m-Te || 88.46 || 0.092 || 119.7 days
| |
| − | |-
| |
| − | |175-Hf || 89.36 || 2.4 || 70 days
| |
| − | |-
| |
| − | |258-Md || 91.0 || 0.3018 || 51.5
| |
| − | |-
| |
| − | |148-Eu || 92.6 || 0.019 || 54.5 days
| |
| − | |-
| |
| − | |151-Gd || 93.21 || 0.0019 || 124 days
| |
| − | |-
| |
| − | |160-Tb || 93.919 || 0.0566 || 72.3 days
| |
| − | |}
| |
| − | | |
| − | The following isotopes have mechanisms that are larger than a 2 neutron/proton knockout and larger than 1n1p knockout:
| |
| − | 257-Fm, 258-Md, 148-Eu.
| |
| | | | |
| | == First Observation of Se lines== | | == First Observation of Se lines== |
| Line 249: |
Line 89: |
| | All runs lasting less than 214 seconds have time stamp that gives real time if you divide by clock frequency of 20 MHz. The first 32 bits are used for a real time measurement. | | All runs lasting less than 214 seconds have time stamp that gives real time if you divide by clock frequency of 20 MHz. The first 32 bits are used for a real time measurement. |
| | | | |
| − | == Detector Efficiency ==
| |
| | | | |
| − | Below is the runlist for finding the efficiency of the detector at position R
| + | == MDA and Se mass Calculations == |
| | + | [[LB MDA/Se Mass Calculations]] |
| | + | |
| | + | ==IAC Detector Efficiencies == |
| | + | |
| | + | [[LB PAA IAC Detector Efficiencies]] |
| | | | |
| | + | ==IAC Detector Calibrations== |
| | | | |
| − | {| border="3" cellpadding="5" cellspacing="0"
| + | [[LB April DetB DetA Calibration]] |
| − | | Source || Serial # || Reference Date || Activity || Start || Stop || Live
| |
| − | |-
| |
| − | | Na-22 || 129743 || 7-01-08 || 9.427 microCi || 15:49 || 16:19 || 1796.803
| |
| − | |-
| |
| − | | Cs-137 || 129793 || 7-01-08 || 1.006 microCi || 14:25 || 14:56 || 1879.606
| |
| − | |-
| |
| − | | Mn-54 || 129807 || 7-01-08 || 11.77 microCi || 15:00 || 15:30 || 1793.420
| |
| − | |-
| |
| − | | Co-60 || 129740 || 7-01-08 || 10.42 microCi || 15:33 || 15:43 || 569.725
| |
| − | |-
| |
| − | |}
| |
| | | | |
| − | Below are the theoretical calculations for the theoretical decay frequencies
| + | ==Runlists== |
| | + | [[LB PAA Runlist 4/01/16 - 06/02/16]] |
| | | | |
| − | Na-22, 9.427micro Ci on July 1, 2008, half life 2.602 +/- 0.002 years, 99.937% for 1274.52 and 178.8 for 511 line , activity in March 31, 2016 =1.196micro Ci
| + | [[LB March 2017 Runlist]] |
| − | := <math>\left (0.99937 \right )\left ( 1.196 \times 10^{-6} \mbox{Ci} \right) \left (\frac{ (3.7 \times 10^{10} \mbox{Hz}}{\mbox{Ci}} \right)= 44,224 Hz </math> for the 1274 line
| |
| | | | |
| − | := <math>\left (1.788 \right )\left ( 1.196 \times 10^{-6} \mbox{Ci} \right) \left (\frac{ (3.7 \times 10^{10} \mbox{Hz}}{\mbox{Ci}} \right)= 79122.6 Hz </math> for the 511 line
| + | [[LB_May_2017_Irradiation_Day]] |
| | | | |
| − | Cs-137, 661.660 line, 85.21% * 1.066micro Ci on July 1, 2008, half life 30.0 +/- 0.2 yrs, March 31, 2016 activity = 0.891micro Ci expected rate for 661 line
| + | =Data Analysis= |
| | | | |
| − | := <math>\left (0.8521 \right )\left ( 0.891 \times 10^{-6} \mbox{Ci} \right) \left (\frac{ (3.7 \times 10^{10} \mbox{Hz}}{\mbox{Ci}} \right)= 28091.2 Hz </math>
| |
| | | | |
| − | Mn-54, on July 1, 2008, half life =312.20 +/- 0.07 days, 99.975% intensity on 834.826 , March 31, 2016 activity =0.02328micro Ci
| + | [[LB_Feb2017_Se_Investigations]] |
| | | | |
| − | := <math>\left (0.99975 \right )\left ( 0.02328 \times 10^{-6} \mbox{Ci} \right) \left (\frac{ (3.7 \times 10^{10} \mbox{Hz}}{\mbox{Ci}} \right)= 861.1 Hz </math> for the 834 line
| + | =References= |
| | | | |
| | | | |
| − | Co-60, 10.42micro Ci July 1, 2008, half life 5.271 +/- 0.001 years, 99.0 % for 1173.237 and 99.9824 % for 1332.501, March 31, 2016 activity=3.759micro Ci
| + | [[User_talk:Brenleyt]] |
| | | | |
| | | | |
| − | := <math>\left (0.99 \right )\left ( 3.759 \times 10^{-6} \mbox{Ci} \right) \left (\frac{ (3.7 \times 10^{10} \mbox{Hz}}{\mbox{Ci}} \right)= 137692.17 Hz </math> for the 1173 line
| + | <references/> |
| | | | |
| | + | [[File:Krouse_CanJournChem_40_1962_p367.pdf]] |
| | | | |
| − | := <math>\left (0.999824 \right )\left ( 3.759 \times 10^{-6} \mbox{Ci} \right) \left (\frac{ (3.7 \times 10^{10} \mbox{Hz}}{\mbox{Ci}} \right)= 139058.52 Hz </math> for the 1332 line
| + | Goryachev, A. M., & Zalesnyy, G. N. (n.d.). The studying of the photoneutron reactions cross sections in the region of the giant dipole resonance in zinc, germanium, selenium, and strontium isotopes. Retrieved September 16, 2016, from http://www-nds.indcentre.org.in/exfor/servlet/X4sSearch5?EntryID=220070 |
| | | | |
| − | [[SeRun_01-11-16]]
| + | Goryachev, B. I., Ishkhanov, B. S., Kapitonov, I. M., Piskarev, I. M., Piskarev, V. G., & Piskarev, O. P. (n.d.). Giant Dipole Resonance on Ni Isotopes. Retrieved October 26, 2016, from http://www-nds.indcentre.org.in/exfor/servlet/X4sGetSubent?reqx=119235&subID=220597006&plus=1 |
| | | | |
| − | [[SeRun_03-07-16]]
| |
| | | | |
| − | =References=
| |
| | | | |
| − | <references/>
| + | Handbook on Photonuclear data for applications, cross sections, and spectra. (2000, October). Retrieved November 4, 2016, from http://www-pub.iaea.org/MTCD/Publications/PDF/te_1178_prn.pdf |
| | | | |
| | =MSDS= | | =MSDS= |
Using PAA ro measure Selenium concentrations.
According to Krouse<ref name="Krous1962"> H.R. Krause and H.G. Thode,"Thermodynamic Properties and Geochemistry of Iosotopic Compounds of Selenium",.Can. J. Chem., vol 40, pg 367</ref>
, the fractional concentration of Se-82/Se-76 in plant material is observed to be less than from primordial (meteoric) concentrations by as much as 1.2%. Anaerobic bacteria are known to reduce selenates and senelites in biological systems. This may be the reason plant material has fractionation of selenium isotopes. They also observe excess concentrations of up to 0.4% in soil.
Plant material appears to detect environmental selenium.
Can one use plant material to measure the provenance of selenium?
Se_Overview_PrevMeas
As shown in the Figure below, the Se-82/Se-76 ratio varies from -1.2% to +0.2% for plant materials but remains relatively constant for other materials. The variations in plant material has been described as being due to differences in the bacteria residing in the plant. The question to investigate is whether or not these variations in the concentration can be used to determine the provenance of the sample.
Below is a table listing the natural abundances of Selenium
Natural abundance of selenium
| Isotope |
Abundance
|
| Se-74 |
0.86%
|
| Se-76 |
9.23%
|
| Se-77 |
7.60%
|
| Se-78 |
23.69%
|
| Se-80 |
49.80%
|
| Se-82 |
8.82%
|
Below are possible PAA reactions that may be used to observe specific Se isotopes
| Reaction |
Half-life |
Relative activity |
Gamma-rays, keV (BR)
|
| Se-74(gamma,n)Se-73 |
7.1 h |
1.5E-1 |
361 (100)
|
| Se-74(gamma,n)Se-73m |
39 m |
3.2 |
402 (4)
|
| Se-74(gamma,np)As-72 |
26 h |
1.0E-3 |
834 (100)
|
| Se-76(gamma,n)Se-75 |
120 d |
1.3E-2 |
265(29)
|
| Se-77(gamma,p)As-76 |
26.4 h |
4.4E-2 |
559(44)
|
| Se-78(gamma,p)As-77 |
38.8 h |
8.6E-2 |
239(2)
|
| Se-80(gamma,n)Se-79m |
3.9 m |
5.9 |
96(10)
|
| Se-80(gamma,np)As-78 |
1.5 h |
2.2E-2 |
614(54)
|
| Se-80(gamma,p)As-79 |
8.2 m |
1.3 |
96(9)
|
| Se-80(gamma,[math]a[/math]p)Ge-75 |
83 m |
2.8E-1 |
265(11)
|
Can one perform PAA measurements of Se-82 and Se-76?
Se_PAA_Reactions
Experiments
PAA Selenium/Soil Experiments
LB Se PAA Horse Feed Experiment
Background Signals
PAA_BackGrd_Det_A
Nickel Normalization
LB PAA Nickel Investigation
First Observation of Se lines
Using the 44 Machine at 7 kW power and 44 meV incident electron energy to produce a bremsstrahlung spectrum with a mean energy of 15 meV.
All runs lasting less than 214 seconds have time stamp that gives real time if you divide by clock frequency of 20 MHz. The first 32 bits are used for a real time measurement.
MDA and Se mass Calculations
LB MDA/Se Mass Calculations
IAC Detector Efficiencies
LB PAA IAC Detector Efficiencies
IAC Detector Calibrations
LB April DetB DetA Calibration
Runlists
LB PAA Runlist 4/01/16 - 06/02/16
LB March 2017 Runlist
LB_May_2017_Irradiation_Day
Data Analysis
LB_Feb2017_Se_Investigations
References
User_talk:Brenleyt
<references/>
File:Krouse CanJournChem 40 1962 p367.pdf
Goryachev, A. M., & Zalesnyy, G. N. (n.d.). The studying of the photoneutron reactions cross sections in the region of the giant dipole resonance in zinc, germanium, selenium, and strontium isotopes. Retrieved September 16, 2016, from http://www-nds.indcentre.org.in/exfor/servlet/X4sSearch5?EntryID=220070
Goryachev, B. I., Ishkhanov, B. S., Kapitonov, I. M., Piskarev, I. M., Piskarev, V. G., & Piskarev, O. P. (n.d.). Giant Dipole Resonance on Ni Isotopes. Retrieved October 26, 2016, from http://www-nds.indcentre.org.in/exfor/servlet/X4sGetSubent?reqx=119235&subID=220597006&plus=1
Handbook on Photonuclear data for applications, cross sections, and spectra. (2000, October). Retrieved November 4, 2016, from http://www-pub.iaea.org/MTCD/Publications/PDF/te_1178_prn.pdf
MSDS
Selenium shot, amorphous, 2-6 mm, Puratronic, 99.999% Alfa Aesar product # 10603 File:AlphaAesarSelenium MDSD.pdf
Informative links
http://www.deq.idaho.gov/regional-offices-issues/pocatello/southeast-idaho-phosphate-mining/southeast-idaho-selenium-investigations/
https://inldigitallibrary.inl.gov/sti/3169894.pdf
http://giscenter.isu.edu/research/Techpg/sisp/index.htm
PAA_Research
