Table 4 Porewater water chemistry from Seaplane Lagoon, Alameda NAS compared with sulfide, carbonate, phosphate, silicate, oxide, and hydroxide minerals reported as the saturation index at 25°C (log SI). Calculations used trace and major elements; sulfide and sulfate are from core SC4 and total inorganic carbon is from core SC2

SC4-1

1.5

-0.1

-16.2

7.4

14.4

8.9

1.0

-3.0

2.4

-1.3

4.0

SC4-2

4.5

-0.1

-15.1

7.5

14.0

9.1

0.9

-3.2

2.5

-0.8

3.9

SC4-3

7.5

1.2

-15.0

7.3

-2.7

3.0

-0.4

3.56

SC4-4

10.5

0.6

-13.8

10.9

-2.5

3.0

-0.1

3.6

SC4-5

13.5

0.2

-15.1

7.9

-2.6

5.6

2.2

5.0

SC4-6

16.5

-0.2

-14.9

8.1

-2.4

2.7

-0.4

3.8

SC4-7

19.5

-0.1

-15.0

7.7

-2.8

2.5

-0.4

3.9

SC4-8

22.5

0.2

-14.9

8.3

-3.0

2.6

-0.4

3.9

SC4-9

25.5

-15.0

7.9

-3.7

-0.7

3.9

SC4-10

28.5

0.0

-15.2

7.3

-4.6

2 2

-0.5

4.0

SC4-11

31.5

0.6

-14.6

7.7

-4.9

2.6

-0.2

3.8

SC4-12

34.5

0.6

-14.4

7.7

2.5

0.2

3.8

Carbonates

Sample ID

Depth/cm

CaCO₃calcite

CdCO₃ otavite

Cu₂CO₃(OH)₂ malachite

FeCO₃ siderite

MnCO₃ rhodochrosite

NiCO₃

PbCO₃ cerussite

ZnCO₃ smithsonite

SC4-1

1.5

-1.1

-16.2

-29.5

-4.5

-5.2

-11.1

-14.9

-9.9

SC4-2

4.5

-0.8

-16.1

-29.0

-4.5

-5.3

-11.0

-14.4

-9.9

SC4-3

7.5

0.9

-13.5

-27.7

-3.5

-9.2

-12.6

-8.9

SC4-4

10.5

1.1

-14.0

-20.2

-3.1

-9.0

-12.2

-8.7

SC4-5

13.5

0.8

-14.7

-26.9

-3.5

-6.6

-10.1

-7.6

SC4-6

16.5

1.0

-14.9

-26.5

-3.2

-.95

-12.6

-8.8

SC4-7

19.5

0.9

-14.8

-27.4

-3.6

-9.6

-12.6

-8.6

SC4-8

22.5

1.1

-14.4

-26.1

-3.6

-9.4

-12.5

-8.5

SC4-9

25.5

0.9

-27.0

-4.3

-12.8

-8.5

SC4-10

28.5

-0.5

-15.8

-29.4

-6.4

-10.9

-13.8

-9.6

SC4-11

31.5

1.3

-13.8

-27.1

-5.4

-9.3

-12.1

-8.4

SC4-12

34.5

1.3

-13.7

-26.9

-9.2

-11.6

-8.3

Silicates

Sample ID

Depth/cm

PbHPO₄

Ca₅OH(PO₄)₃ apatite

Pb₅PO₄Cl₃ pyromorphite

β-Zn(OH)₂

SiO₂ quartz

SiO₂ β-cristobalite

Mg₅Al₂Si₃0₁₀(OH)₈ 7A-chlorite

SC4-1

1.5

-11.6

1.8

-55.5

-10.1

0.7

-0.3

-0.1

SC4-2

4.5

-11.4

2.5

-53.9

-10.1

0.8

0.2

2.8

SC4-3

7.5

-11.2

4.6

-51.8

-9.8

0.6

-0.4

5.5

SC4-4

10.5

-10.9

5.1

-50.3

-9.6

0.7

-0.3

7.2

SC4-5

13.5

-8.6

3.5

-39.5

-8.9

0.8

-0.2

3.8

SC4-6

16.5

-11.2

4.3

-52.5

-10.1

0.7

-0.3

5.1

SC4-7

19.5

-11.2

3.5

-52.6

-10.1

0.8

-0.2

4.3

SC4-8

22.5

-11.2

4.1

-52.6

-10.1

0.8

-0.2

4.5

SC4-9

25.5

-11.5

3.6

-52.3

-10.2

0.8

-0.2

3.8

SC4-10

28.5

-10.7

2.8

-53.1

-10.3

0.8

-0.2

3.6

SC4-11

31.5

-10.9

4.3

-51.5

-10.2

0.8

-0.2

4.7

SC4-12

34.5

-10.5

4.2

-51.2

-10.1

0.8

-0.3

5.2

Oxides/hydroxides/phosphates

Sample ID

Depth/cm

A1(OH)₃gibbsite

Cd(OH)₂

Cr₂O₃ eskolaite

CuO tenorite

Fe(OH)₂

FeOOH goethite

Ni(OH)2

Mn(OH)₂

MnHPO₄

Pb₃-(PO₄)₂

Ni₃-(PO₄)₂

Mn₃- (PO₄)₂

Cd₃-(PO₄)₂

Cu₃(PO₄)₂

Zn₃(PO₄)₂4H₂O hopeite

FePO₄. 2H₂O strengite

FeCr₂O₄ chromite

MgCr₂O₄ magnesio-chromite

SC4-1

1.5

0.6

-20.4

-1.0

-13.8

-7.3

-4.6

-9.1

-9.4

-1.2

-41.4

23.1

-22.7

-53.0

-47.0

-24.6

-13.2

8.3

4.8

SC4-2

4.5

0.9

-20.4

1.8

-13.6

-7.3

-4.4

-8.9

-9 5

-1.6

-40.8

-23.5

-23.8

-53.5

-47.1

-25.4

-13.4

0.9

0.9

SC4-3

7.5

0.0

-18.4

4.3

-13.2

-7.8

-8.4

-1.4

-39.2

-22.0

-22.2

-49.5

-47.9

-26.5

4.4

SC4-4

10.5

0.3

-19.0

7.0

-9.5

-7.7

-8.1

-1.2

-38.2

-21.8

-21.4

-51.5

-37.0

-26.1

7.2

SC4-5

13.5

0.2

-20.0

2.3

-13.1

5./

-8.8

-1.3

-32.6

-14.6

-22.3

-53.3

-46.4

-22.6

2.0

SC4-6

16.5

0.4

-20.3

3.1

-12.8

-8.5

-8.6

-1.2

-39.6

-23.2

-21.9

-54.3

-45.9

-26.3

3.0

SC4-7

19.5

0.7

-20.4

5.4

-13.4

-8.8

-9.1

-1.5

-39.7

-23.7

-23.0

-54.2

-47.2

-26.0

5.0

SC4-8

22.5

0.4

-20.0

2.8

-12.8

-8.7

-9.2

-1.6

-39.5

-23.5

-23.4

-53.0

-45.3

-26.0

2.5

SC4-9

25.5

1.0

1.8

-13.3

-10.1

-2.0

-40.0

-25.1

-45.9

-25.3

1.1

SC4-10

28.5

1.8

-20.5

0.8

-14.0

-9.4

-11.2

-2.7

-39.1

-23.8

-27.5

-52.9

-47.2

-24.8

-0.3

SC4-11

31.5

0.5

-19.6

3.3

-13.4

-8.8

-11.2

-3.5

-38.8

-23.5

-29.1

-51.7

-47.0

-26.1

3.0

SC4-12

34.5

0.8

-19.6

3.7

-13.3

-8.8

-37.6

-23.6

-51.6

-46.8

-25.9

3.4