Poisening by arsenic

1
Poisening by arsenic in drinking water
WHO limit 10 µg/L
Black Foot Disease
Skin Cancer
2
The Global Arsenic Problem
70-100 mill people affected
3
Bangladesh Groundwater
4
N. Vietnam
5
red river
red river
transect
dyke
Fig 1
6

• The Dan Phuong
• Transect
• PVC casing 60 mm Ø
• Variable depth -22 m
• Screen 30 cm
• Seal through clay layer

7
O2 mmol/L
clay
Elevation m
Distance m
8
Fe2 mmol/L
clay
Elevation m
Distance m
9
CH4 mmol/L
clay
Elevation m
Distance m
10
As-total, µmol/L
clay
Elevation m
Distance m
1 µmol/L As 75 ug/L As
11
Projekt Indhold Kemi arsens geokemi org. stof
nedbrydning og redox geokemisk
modellering Fysik vandtransport i
jordlag grundvandsmodel Biologi arsen
forgiftning
12
Kemi

• Dataset one depth profile
• Calculate charge balance
• Calculate redox potential
• Calculate mineral saturation (PHREEQC)
• Interpret redox sequences

13
pH 6.76
V
V
III
2pe -3pH 21.14
III
Equal activities
14
Arsenic in groundwater at Dan Phuong
15
Redox sequences
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Fysik

• Dataset grundvandspotentialer mm
• Beregn grundvandshastigheder vha Darcys lov
• Grundvandsdatering vha radioisotoper
• Beregn grundvands bevægelse ud fra masse balance

17
red river
red river
transect
dyke
Fig 1
18
(No Transcript)
19
Darcys law
vH20
vH20
K 10-4 m/s e 0.3
20
Grundvandsdatering med radioaktive isotoper
0.5 m/yr
DanPhuongModel7b.xls
Fig 3
21
The mass balance in a homogeneous aquifer