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Surface Water Geochemistry of Deckers Creek Basin Geology 399 Qingyun Sun.

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Presentation on theme: "Surface Water Geochemistry of Deckers Creek Basin Geology 399 Qingyun Sun."— Presentation transcript:

1

2 Surface Water Geochemistry of Deckers Creek Basin Geology 399 Qingyun Sun

3 Environmental Experts Say: Acid Mine Drainage == in West Virginia

4 Acid Mine Drainage

5 Surface Water of the Stream

6 The water of Deckers Creek is seriously polluted by Acid Mine Drainage (AMD). The geochemically study and graphical analysis are based on the surface water samples of Deckers Creek. This paper is to find out the pollution sources and suggest the pollution control methods. Introduction

7 Figure 1

8 Sample Site Location Map Deckers Creek Figure 2

9 Analytical Chemical Contents Total Acidity pH Total Alkalinity Total Iron(Fe) Total Sulfate(SO 4 2- ) Total Nitrate(NO 3 - ) Total Chloride(Cl - ) Total Calcium (Ca) Total Magnesium(Mn) Total Sodium(Na) Total Potassium(K) Conductivity Table 1

10 Water Geochemistry Data Table 2

11 Figure 3

12 Factor Analysis of the DataFigure 4

13 Data Sets Factor AnalysisFigure 5

14 Data Sets Factor AnalysisFigure 6

15 Correlation Matrix Correlations (Pearson) Acidity Conduct. [H] Fe SO4 NO3 Cl- Ca Na Cond [H] Fe SO NO Cl Ca Mn Na K Regression Equation Acidity = Conductivity [H] Fe SO NO Cl Ca Mn Na K Table 3

16 Factors Affecting Water Acidity Acidity Nitrate(NO 3 - ), Chloride(Cl - ), Sodium(Na) and Potassium(K) have very small correlation with Acidity, the water acidity is most probably influenced by irons, conductivity, Mn, H and sulfide. Fe H 2 O===> Fe(OH) 3 + 3H + 2Mn 2+ +O 2 + 2H 2 O===> 2MnO 2 + 4H + The sulfite acid comes from the oxidization of pyrite: 2FeS 2 + 7O 2 + 2H 2 O ===== 2Fe SO H + 4Fe 2+ + O 2 + 4H + ===== 4Fe H 2 O FeS Fe H 2 O ===== 15Fe SO H + The reasons may be:

17 Remove NO 3 -, Cl -, Na and K and get the acidity equation from regression analysis: Acidity = [H + ] [Fe] [SO 4 ]-0.779[Mn 2+ ] Figure 7

18 The cluster analysis (ignore some species) Figure 8

19 Limestone Dangerous Water Bad Water Figure 9

20 The Total Acidity Analysis Figure 10

21 1. Water Quality Generally speaking, the surface water of Deckers Creek has been seriously contaminated by the acid and dissolved metals. Factor analysis reveals that the acidity of the water is mainly caused by sulfide, low pH, iron, Mn and so on. D19-TK27 are in the mining area, where acid mine drainage makes the water quality worse with lower pH and higher dissolved salts (Cluster Analysis). Cluster analysis points out that the water at the point (TH3) is very toxic because an abandoned mine discharges the acid mine drainage and pollutes the stream. From D17 to D10, the acidity begins to reduce because there exist limestone that can neutralize a part of acidity. Conclusion

22 2. Acid Formation The formation of the Deckers Creek acidity water mainly results from that the pyrite is oxidized by the O 2 and water. The precipitation of iron and Mn oxide can generate acid, too. 2FeS 2 + 7O 2 + 2H 2 O ===== 2Fe SO H + 4Fe 2+ + O 2 + 4H + ===== 4Fe H 2 O FeS Fe H 2 O ===== 15Fe SO H + Fe H 2 O===> Fe(OH) 3 + 3H + 2Mn 2+ +O 2 + 2H 2 O===> 2MnO 2 + 4H + Limestone can neutralize the water acidity by promoting pH. CaCO 3 + H + ===== Ca 2+ + HCO 3 -

23 3. Total Acidity Equation The acidity of the Deckers Creek water does not result from NO 3 -, Cl -, Na and K, which can be removed from regression analysis. Comparing the equation with the theoretical equation, we may find both the equations are similar. The acidity equation from Regression Analysis: Acidity = 2.27[Fe] [Mn 2+ ] [H + ] [SO 4 ] The theoretical equation: Acidity = 50(  [M]/Equivalent Weight pH ) = 50( 3[Fe 3+ ]/56 + 2[Fe 2+ ]/56 + 2[Mn 2+ ]/ pH )  2.68[Fe 3+ ] [Fe 2+ ] [Mn 2+ ] + 50[H + ]

24 4. Problem and Suggestion After flowing over limestone generation industrial region, the acidity of was neutralized a little. However, the deficient limestone can not meet more addition of acid mine drainage, it is necessary to add limestone into the stream water. For some very toxic water such as point TH3, the discharge has to be collected and treated separately, then let it mix into Deckers Creek. There still exist some unknown points waiting to be further studied, where the water quality unstable and the analysis results of the water samples are controversy with what we have expected.

25 Good Bye!


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