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.