Does%20arsenic,%20in%20groundwaters%20of%20the%20compound%20Rhine-Meuse%20delta,%20menace%20drinking%20water%20supply%20in%20the%20Netherlands?

1
Does arsenic, in groundwaters of the compound
Rhine-Meuse delta, menace drinking water supply
in the Netherlands?
2
Pieter J. Stuyfzand 1,2, Igor Mendizabal 1,2,
Peter van Rossum 1
1

• IAH -Meeting, Utrecht, 29 Nov 2006

2
Active well fields and surface water intake
points, for drinking water supply
3
Water resource types in the Neths (for drinking
water supply) and their characteristics
1,250 Mm3/y produced by 246 well fields 16
surface water treatment plants
4
21 Loosdrecht (B)
12 Zwijndrecht (U)
14 Tolkamer (B)
11 Macharen (A)
38 Oostrum (A)
12 Dorst (B)
No trends 1989-2002
5
Mean composition of raw water from well field
types in the Neths, in 1989
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Plot of As versus resp. Fe and HCO3 for all well
fields (for drink. water supply) in Neths
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Plot of As versus resp. PO4 and pH for all well
fields (for drink. water supply) in Neths
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Plot of As versus resp. SO4 and NO3 for all well
fields (for drink. water supply) in Neths
9
Plot of As versus resp. As in sludge and depth,
for all well fields (for drink. water supply) in
Neths
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Concl.1 On a large scale (well fields), As does
not pose problems to drinking water supply

• Concentrations in raw groundwater from well
  fields 0.1 38 µg/L. Stable situation during
  past 16 years
• Enough Fe2 in groundwater (0.01-25 mg/L) to bind
  most As upon aeration and RSF. AsDW 0.05-7
  µg/L
• Water treatment sludges ? high As content
  (10-3100 mg/kg d.w.) ? hazardous waste. Ferric
  sludges used for making construction bricks
• No clear relations between As and PO4, Fe, Mn,
  SO4, HCO3, DOC. Max with pH 7-7.5, NO3 lt 2.
• Low As in limestone aquifers and basin AR systems
  
• High(er) As in sandy (conf) aquifers and RBF
  systems

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Sites with detailed hydrogeo-chemical surveys,
incl. As behaviour
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Site 1 Changes in TEs (incl As) in coastal dune
groundwater along a flow path (Stuyfzand, 1991)
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Site 2 Phreatic groundwater under agricul-tural
stress, Vierlingsbeek (data C.v.Beek)
14
Site 3 RBF flow path near Opperduit (1983 and
1994/5), with As isoconc lines
1.2 y
2.5 y
8 y
5 y
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Site 3 Detailed survey of TEs in Rhine RBF (site
Opperduit) in 1983
Conc 0.45 um filtr sample
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Site 4 RBF-study in compound Rhine Meuse
estuary (Hollandsch Diep)
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Site 4 Distribution of watertypes (incl.
distinction in age and recharge area)
m MSL
100 m
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Site 4 Different interactions of RBF with recent
sludge deposits in Hollandsch Diep (R-M estuary)
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Site 5 high As-belt south of Amsterdam (data P.
van Rossum)
Area south of Amsterdam
Fe(OH)3
PO4, NO3, SO4, DOC, SiO2
FeS2
FeOOH, FeS2
CH4
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Site 6Pretreated Rhine water along an AR flow
path, dunes Zandvoort 1983
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Site 7 AR with Meuse River water, near The Hague
(DZH) snapshot 2006
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Redox zoning on Langerak AR pilot, after 1.5 yr
injection
Site 8 DWI
As in layer C (very reactive FeS2) on Langerak
site
A
B
C
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Trace Elements from pyrite are largely
immobilized in fresh Fe(OH)3- precipitates
(Stuyfzand, 2001)

• High As-concentrations if
• ?SO4 high
• ?x or t small
• pH high
• PO4 and H4SiO4 high

• Fe0.98Co0.003Ni0.01Zn0.01S2As0.005
• O2 NO3- xH4SiO4
• SixFe(OH)3Co0.0027Ni0.009Zn0.009(HAsO4)0.004
• 2SO4 2- 0.001 (H3AsO3 Ni2 Zn2)
• N2 0.0003 Co2

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? Does ripening of ferrihydrite to goethite
mobilize As?
Pumping wells often clog by mixing of Fe2 with
O2/NO3-water
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Concl.2 on small scale (indiv wells) As may
become nasty for drinking water supply

• As mobilization by
• (Sub)recent disturbances of hydrol. system, like
  drawdown/rise of watertables, flow reversal, flow
  accelleration etc.
• (Sub)recent changes in quality infiltrating
  water, esp. rise of PO4, SO4, NO3, HCO3, DOC, F,
  temp,
• Reducing gases, esp.CH4 (and H2S)
• Needed / to be studied
• As behaviour in SIR and ASR systems
• An As risk assessment method

26
Concl.3 As mobilizing processes and bias
H2S 4 HAsO42- 6H ? 4 H3AsO3 SO42- CH4
4HAsO42- 8H ? 4H3AsO3 CO2 2H2O
Positive As-bias FeS2 / Fe(OH)3 particles
dissolved by HNO3 due to lack of (sufficient)
filtration Negative As-bias filtration in lab of
oxidized sample with Fe2
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Changes in spatial distribution of groundwater
types in Neths land recl, drainage, river
endikement, Q etc.
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Ni and Fe in phreatic groundwater under
agricultural stress, Vierlingsbeek (data v.Beek)
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NO3 and SO4 in phreatic groundwater under
agricultural stress, Vierlingsbeek (data v.Beek)
High As
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Site 3 Mean composition Rhine River and 3 redox
types of River Bank Filtrate from pumping wells
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Site 4 Interpreted age of Rhine bank filtrate in
cross section, in 1997-1999
Water age year
m MSL
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Mean composition of raw water from well field
types in the Neths, in 1989
33
Water resource types in the Neths (for drinking
water supply) and their characteristics
1,250 Mm3/y produced by 246 well fields 16
surface water treatment plants