Anatomy of the simplest C Program Sen Zhang SUNY Oneonta Oneonta, NEW YORK © 2004 -@2005.
USING FREE GEOCHEMICAL SOFTWARE FROM THE U.S. GEOLOGICAL SURVEY DEVIN CASTENDYK STATE UNIVERSITY OF...
-
Upload
tyrone-haynes -
Category
Documents
-
view
212 -
download
0
Transcript of USING FREE GEOCHEMICAL SOFTWARE FROM THE U.S. GEOLOGICAL SURVEY DEVIN CASTENDYK STATE UNIVERSITY OF...
USING F
REE GEOCHEMIC
AL
SOFTW
ARE FROM T
HE U.S
.
GEOLOGIC
AL SURVEY
DEV I N
CA S T EN
DY K
S TAT E UN
I VE R
S I TY O
F NEW
YO
RK ,
ON
EON
TA
DE V I N
. CA S T EN
DY K@
ON
EON
TA . ED
U
WHY USE?
I want students to interpret geochemical reactions that occur along flow paths
FREE SOFTWARE
Web site: http://water.usgs.gov/software/
Piper Plot GenerationGW_CHARTVisualize and discuss differences in water chemistry
Thermodynamic equilibrium softwarePHREEQCiSpeciate water (applied thermodynamics)Calculate charge imbalanceIdentify over-saturated and under-saturated minerals
CREATE PIPER PLOT WITH GW_CHART
All boxes must be filled, no red boxes
Select number of data points and units at the bottom left
All boxes must be filled (no red boxes) Add up values for TDS if needed
Program will calculate CO32- from HCO3
- at specified Temperature and pH
Must enter HCO3- first
Record symbols on a separate paper
GRAPHICS OPTIONS
Format graph with hammer tool Show numbers (values on grid lines) Make symbols proportional to TDS Add grid lines Set color individually
Legend Add names
Plot Use landscape view
HOW TO INTERPRET
Dominant cation and dominant anion characteristics of the water
Differences and similarities between waters based on ion relationships (equivalence)
TDS comparisons
Changes occurring along a flow path
BEFORE USING PHREEQCI
Review thermodynamics
Look at database to see thermodynamic data
Find good geochemical dataset Major Cations, Major Anions, HCO3, Si, Fe, Al, Mn Redox pair (Fe2/Fe3, NH4/NO3)
PHREEQCI
General Give Description Enter pH, pe, and temperature State how redox should be determined (pe or pair)
Individual element input Change default units to ug/L Enter values Change units for anions (Cl, NO3, SO4) Advanced: allow model to calculate pH using charge imbalance
Highlight “Simulation 1”
Click on little black dot
Save
EXECUTE PROGRAM
Highlight title
Run
Change database if you like for more parameters Click on box beside database Select “minteq.dat” Click “Start” and then “Dismiss”
OUTPUT FILES
Description of Solution pH and redox (if you allow model to calculate) Ionic strength Percent Error from charge imbalance (< 10%)
Distribution of Species Individual component concentrations and activity coefficients (user
specifies model) What is dominant Fe species in solution?
Saturation indices Negative are under-saturated minerals (dissolving?) Positive are over-saturated minerals (precipitating?)
CAUTIONS
Lots of uncommon minerals in the database
Model based exclusively on thermodynamic equilibrium Infinite time Does not consider biological influence
ADVANCED TECHNIQUES
Allow PHREEQCi to calculate redox conditions based on known redox pairs
Allow PHREEQCi to calculate pH based on charge imbalance
Surface adsorption
Cation exchange
Equilibrium phase (solid or gas)
Mix solutions
Define reactions