1. Bulgarian Academy of Sciences, Sofia, Bulgaria
Thermodynamic Modeling of Inorganic Chemical Speciation in River Waters Affected by Mine Water Discharges
D. Rabadjieva, S. Tepavitcharova, T. Todorov, M. Dassenakis, V. Paraskevopoulou, M. Petrov
D. Rabadjieva
Bulgarian Academy of Sciences, Sofia, Bulgaria
PROMITHEAS-2, 8,9 October 2008, Athens (Greece)

2. CONTENT Introduction Purpose Experiments Field Studies
Chemical Analyses
Results
Thermodynamic Modeling of Inorganic Species
Theoretical Base
Computer Programs
Review of Databases
Conclusions
PROMITHEAS-2, 8,9 October 2008, Athens (Greece)

3. INTRODUCTION
PROMITHEAS-2, 8,9 October 2008, Athens (Greece)

4. INTRODUCTION
Natural surface waters - MULTICOMPONENT SYSTEMS Major components of natural genesis Na+, K+, Mg+2, Ca+2, HCO3-, Cl-, SO4-2 Major pollutants nutrients trace metals
PROMITHEAS-2, 8,9 October 2008, Athens (Greece)

5. INTRODUCTION
MONITORING The actual collection of information at set locations and at regular intervals in order to provide the data which may be used to define current conditions, establish trends,etc. PROBLEM It usually shows the total content of the pollutants, without defining their chemical species, which determine element toxicity and bioavailability in the ecosystem.
PROMITHEAS-2, 8,9 October 2008, Athens (Greece)

6. specific form of an element defined as isotopic composition
INTRODUCTION
Chemical species
specific form of an element defined as
isotopic composition
oxidation state
complex or molecular units
PROMITHEAS-2, 8,9 October 2008, Athens (Greece)

7. INTRODUCTION ANALYTICAL METHODS
Hyphenated instrumental analytical methods
HPLC-ICP-MS ;
PROBLEMS
Time consuming
Expensive
Applicable to a limited number of species.
SOLUTION
Thermodynamic modeling
PROMITHEAS-2, 8,9 October 2008, Athens (Greece)

8. PURPOSE
Determination of the inorganic chemical species in mining polluted surface waters by: ♦ chemical analyses; and ♦ thermodynamic modeling of the systems. CASE STUDIES: Maresh and Luda Yana rivers Asarel-Medet copper mine in Bulgaria.
PROMITHEAS-2, 8,9 October 2008, Athens (Greece)

9. EXPERIMENTS - Field Studies
Asarel-Medet, an open pit copper mine, is a major producer of pyrite and copper concentrates in Bulgaria and is one of the largest in Europe
PROMITHEAS-2, 8,9 October 2008, Athens (Greece)

10. EXPERIMENTS - Field Studies
Sampling stations in the Asarel mine region
PROMITHEAS-2, 8,9 October 2008, Athens (Greece)

11. EXPERIMENTS - Chemical Analysis
Major ions and Nutrients Spectrophotometry Dissolved Al, Fe, Mn, Pb, Cd, Cu and Zn Atomic Absorption Spectrometry (GFAAS)
PROMITHEAS-2, 8,9 October 2008, Athens (Greece)

12. EXPERIMENTS - Analytical Results
Physicochemical characteristics and chemical parameters in Maresh and Luda Yana rivers waters
pH – 8.8
O2, mg/l
Cl, mg/l –
SO42-, mg/l – 5500
K, mg/l –
Na, mg/l –
Ca, mg/l – 100
Mg, mg/l – 234
PO4, μmol/l –
NO2, μmol/l –
NO3, μmol/l – 466
NH4, μmol/l –
SiO2, μmol/l – 1179
Al, mg/l – 431
Fe, mg/l –
Mn, mg/l –
Cu, mg/l – 274
Zn, mg/l –
Pb, μg/l –
Cd, μg/l – 85
PROMITHEAS-2, 8,9 October 2008, Athens (Greece)

13. EXPERIMENTS - Analytical Results
Suspended materials in Maresh and Luda Yana rivers waters
Measured values
SPM, mg/l – 32.7
Al, mg/l –
Fe, mg/l –
Mn, mg/l –
Cu, mg/l – 1.93
Zn, mg/l – 0.016
Pb, μg/l –
Cd, μg/l – 0.21
PROMITHEAS-2, 8,9 October 2008, Athens (Greece)

14. Centre of Competence MISSION
Sixth Framework Programmе Specific Support Action EC-INCO-CT
Centre of Competence MISSION
Thermodynamic Modeling of Inorganic Species
Theoretical Base
k Mm + j Xin = Mk(Xi)jkm-jn
PROMITHEAS-2, 8,9 October 2008, Athens (Greece)

15. Thermodynamic Modeling of Inorganic Species
Theoretical Base
PROMITHEAS-2, 8,9 October 2008, Athens (Greece)

16. Thermodynamic Modeling of Inorganic Species
Computer programs
PROMITHEAS-2, 8,9 October 2008, Athens (Greece)

17. PHREEQCI computer program
Thermodynamic Modeling of Inorganic Species
Computer Programs
PHREEQCI computer program
Thermodynamic Ion-Association Model
extensions of the Debye-Huckel theory
The formation of each aqueous specie is defined by a mass-action expression with the appropriate thermodynamic constant.
The program claims calculation of the activity coefficients of the species that are valid up to an ionic strength approximately 0.7 mol.kg-1H2O.
PROMITHEAS-2, 8,9 October 2008, Athens (Greece)

18. a,  and m Thermodynamic Modeling of Inorganic Species
Computer Programs
INPUT
pH, toC, total concentrations
DAVIES equations, DATABASE for K, H
CALCULATION
a,  and m
OUTPUT species concentrations
major elements
minor elements
trace elements
PROMITHEAS-2, 8,9 October 2008, Athens (Greece)

19. Thermodynamic Modeling of Inorganic Species
Review of Databases
PROMITHEAS-2, 8,9 October 2008, Athens (Greece)

20. Thermodynamic Modeling of Inorganic Species
Review of Databases
PROMITHEAS-2, 8,9 October 2008, Athens (Greece)

21. Thermodynamic Modeling of Inorganic Species
Results
Major metals speciation distribution in the waters of Maresh and Luda Yana rivers sampling stations
PROMITHEAS-2, 8,9 October 2008, Athens (Greece)

22. Thermodynamic Modeling of Inorganic Species
Results
Trace metals speciation distribution in the waters of Maresh and Luda Yana rivers waters
PROMITHEAS-2, 8,9 October 2008, Athens (Greece)

23. CONCLUSSIONS
The experimental results of this study combined with thermodynamic modelling of the inorganic chemical speciation based on the new database sst2008.dat revealed that the small lake, (location of station Ba1), acted as the main point pollution source.
The acidic conditions that are generally found in this lake and in the downstream affected stations favor the dominance of dissolved metal forms.
High levels of SO42-, Cu, Mg, Al, Mn and Fe were determined in the affected stations.
PROMITHEAS-2, 8,9 October 2008, Athens (Greece)

24. CONCLUSSIONS
The increased concentration of SO42- ions led to their competitiveness in the processes of complex formation. Thus, differently from non impacted river waters, complex sulphate species of major and trace metals appeared in the whole polluted and affected water system at the expense of free Men+ species.
The percentage of free metal species, which are more toxic, increased downstream of station Ba1.
The trace elements decreased downstream mainly due to dillusion, sorption processes, and precipitation.
PROMITHEAS-2, 8,9 October 2008, Athens (Greece)

25. Thank You for the Attention
PROMITHEAS-2, 8,9 October 2008, Athens (Greece)