Analysis of Total Aluminum and Dissolved Aluminum

Louis McDonald and Jeff SkousenPlant & Soil Sciences

West Virginia University

AluminumThe Good The Bad The Ugly

?

2

Where is the Aluminum?

3

Al3+

Aluminum – “Free” Ion

4

Al3+ Complexes

Aluminum Complexes

Inorganic

e.g. fluoride, hydroxide, sulfate, carbonate

Organic

Al3+ O5

Al3+ Complexes

Aluminum Complexes

Inorganic Organic

Smalle.g. acetic, citric

hydroxide

6

Al3+ Complexes

Aluminum Complexes

Inorganic Organic

Small Largee.g. acetic, citric e.g. humic acid,

fulvic acid

hydroxide

7

Al3+ Complexes

Inorganic Organic

Small Large

Where is the Aluminum?

OH-

8

Aluminum ParticlesBy Composition

Aluminum hydroxides and oxides Gibbsite (Al(OH)3)

Aluminosilicates

Phyllosilicates Kaolinite (Si2Al5(OH)4)

Feldspar (KAlSi3O8)

Kaolinite Al2Si2O5(OH)4

9

Aluminum ParticlesBy Size

LargeMediumSmallV. Small

SandsSiltsClaysVery fine clays

Colloids – Al on surface does matter10

Colloids

Al3+

Ca2+, Mg2+, K+, etc.

11

Al3+ Complexes

Inorganic Organic

Small Large

Particles

V. Small

Small

Medium

Large

Very Small Very Large

OH-

12

Al3+ Complexes

Inorganic Organic

Small Large

Particles

Definitely Dissolved Definitely Solid

V. Small

Small

Medium

Large

Very Small Very Large

OH-

13

Al3+ Complexes

Inorganic Organic

Small Large

Particles

Definitely Dissolved Definitely Solid

V. Small

Small

Medium

Large

Very Small Very Large

Filter SizeOperationally Dissolved

OH-

14

The Curious Case of Hydroxide

15

Total Dissolved AlAl3+ Al(OH)4-

16

The Curious Case of Hydroxide

Al3Al1

Al13

From Casey et al. 201017

Al3+ Complexes

Inorganic Organic

Small Large

Particles

Definitely Dissolved Definitely Solid

V. Small

Small

Medium

Large

Very Small Very Large

Filter SizeOperationally Dissolved

OH-

PolynuclearAl

18

Where is the Aluminum?

19

Al3+ Complexes

Inorganic Organic

Small Large

Particles

Definitely Dissolved Definitely Solid

V. Small

Small

Medium

Large

Very Small Very Large

Filter SizeOperationally Dissolved 20

Al3+ Complexes

Inorganic Organic

Small Large

Particles

Definitely Dissolved Definitely Solid

V. Small

Small

Medium

Large

Very Small Very Large

Filter SizeOperationally Dissolved

Why filter? PROPERLY!

21

Al3+ Complexes

Inorganic Organic

Small Large

Particles

Definitely Dissolved Definitely Solid

V. Small

Small

Medium

Large

Very Small Very Large

Filter SizeOperationally Dissolved

What do instruments measure?

22

Acidifying Samples

+ Acid, H+

Al3+

Al – ComplexesAl in SolidsAl on Surfaces

Al3+

H – ComplexesAl in SolidsH on Surfaces

Dissolved Al DissolvedAl

23

Al3+ Complexes

Inorganic Organic

Small Large

Particles

Definitely Dissolved Definitely Solid

V. Small

Small

Medium

Large

Very Small Very Large

Filter SizeOperationally Dissolved

Why might hardness matter?

24

Al3+ Complexes

Inorganic Organic

Small Large

Particles

Definitely Dissolved Definitely Solid

V. Small

Small

Medium

Large

Very Small Very Large

Filter SizeOperationally Dissolved

What is toxic?

25

Al3+ Complexes

Inorganic Organic

Small Large

Particles

Definitely Dissolved Definitely Solid

V. Small

Small

Medium

Large

Very Small Very Large

Filter SizeOperationally Dissolved

What is toxic?

Ingestion orInhalation

26

Al3+ Complexes

Inorganic Organic

Small Large

Particles

Definitely Dissolved Definitely Solid

V. Small

Small

Medium

Large

Very Small Very Large

Filter SizeOperationally Dissolved

What is toxic?

Plants, algae

27

Al3+ Complexes

Inorganic Organic

Small Large

Particles

Definitely Dissolved Definitely Solid

V. Small

Small

Medium

Large

Very Small Very Large

Filter SizeOperationally Dissolved

What is toxic?

Fish acute

28

Al3+ Complexes

Inorganic Organic

Small Large

Particles

Definitely Dissolved Definitely Solid

V. Small

Small

Medium

Large

Very Small Very Large

Filter SizeOperationally Dissolved

What is toxic?

Fish chronic?

29

Al3+ Complexes

Inorganic Organic

Small Large

Particles

Definitely Dissolved Definitely Solid

V. Small

Small

Medium

Large

Very Small Very Large

Filter SizeOperationally Dissolved

What is Total Al? What is dissolved Al?

30

Al3+ Complexes

Inorganic Organic

Small Large

Particles

Definitely Dissolved Definitely Solid

V. Small

Small

Medium

Large

Very Small Very Large

Filter SizeOperationally Dissolved

Questions?

31