The global dimension of Arsenic in ground- and drinking water Chairman: Tony Appelo Welcome! Why, and what is the problem, some background Introduction.

The global dimension of Arsenic in ground- and drinking water

Chairman: Tony Appelo

• Welcome!

• Why, and what is the problem, some background

• Introduction of the speakers

The Global Arsenic Problem

Smedley and Kinniburgh, 2002, AG 17, 517

Bangladesh Groundwater

DPHE and BGS, 2001

data from: DPHE and BGS, 2001

Bangladesh Standard: 0.05 mg/L. Drink 2 L → 0.1 mg As /day

In rice: 0.03 - 0.3 mg/kg Eat 0.3 kg → 0.1 mg As /day (Kapaj et al., 2006, JESH 41, 2399)

The hydration of Fe-oxide surfaces

O

OFe

H2O

surface site

≡FeOH

≡FeOH + H+ ↔ ≡FeOH2+

≡FeOH - H+ ↔ ≡FeO-

Fe2O3 surface

pH = 6.76

5

5

3

3

2 redox forms in water: Arsenate anion, As(5)

Arsenic acid, As(3)

Sorption of anions on ferrihydrite

PZC

PROGRAM

14.15 dr Pauline Smedley (British Geol Survey): Arsenic in groundwater – natural sources, mobilisation controls and the question of human influences

15.00 Prof. dr Marie Vahter (Karolinska Institute): Arsenic in drinking water: threatening the health of millions?

15.45 Break

16.15 Tony Appelo: What is the origin of high As concentrations in groundwater?

16.45 Discussion

17.00 Closure, drinks, etc.