Partner for progress Does arsenic, in groundwaters of the compound Rhine-Meuse delta, menace...
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Partner for progress Does arsenic, in groundwaters of the compound Rhine-Meuse delta, menace drinking water supply in the Netherlands? IAH -Meeting, Utrecht,
Partner for progress Does arsenic, in groundwaters of the
compound Rhine-Meuse delta, menace drinking water supply in the
Netherlands? IAH -Meeting, Utrecht, 29 Nov 2006 Pieter J. Stuyfzand
1,2, Igor Mendizabal 1,2, & Peter van Rossum 1 1 2
Slide 2
2 Active well fields and surface water intake points, for
drinking water supply
Slide 3
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
5 Mean composition of raw water from well field types in the
Neths, in 1989
Slide 6
6 Plot of As versus resp. Fe and HCO 3 for all well fields (for
drink. water supply) in Neths
Slide 7
7 Plot of As versus resp. PO 4 and pH for all well fields (for
drink. water supply) in Neths
Slide 8
8 Plot of As versus resp. SO 4 and NO 3 for all well fields
(for drink. water supply) in Neths
Slide 9
9 Plot of As versus resp. As in sludge and depth, for all well
fields (for drink. water supply) in Neths
Slide 10
10 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 g/L. Stable situation during past 16
years Enough Fe 2+ in groundwater (0.01-25 mg/L) to bind most As
upon aeration and RSF. As DW = 0.05-7 g/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 < 2. Low As in limestone aquifers and basin AR systems
High(er) As in sandy (conf) aquifers and RBF systems
Slide 11
11 Sites with detailed hydrogeo- chemical surveys, incl. As
behaviour
Slide 12
12 Site 1: Changes in TEs (incl As) in coastal dune groundwater
along a flow path (Stuyfzand, 1991 )
Slide 13
13 Site 2: Phreatic groundwater under agricul- tural stress,
Vierlingsbeek (data C.v.Beek)
Slide 14
14 Site 3: RBF flow path near Opperduit (1983 and 1994/5), with
As isoconc lines 1.2 y 5 y 8 y 2.5 y
Slide 15
15 Site 3: Detailed survey of TEs in Rhine RBF (site Opperduit)
in 1983 Conc 0.45 um filtr sample
Slide 16
16 Site 4: RBF-study in compound Rhine Meuse estuary
(Hollandsch Diep)
Slide 17
17 Site 4: Distribution of watertypes (incl. distinction in age
and recharge area) m MSL 100 m
Slide 18
18 Site 4: Different interactions of RBF with recent sludge
deposits in Hollandsch Diep (R-M estuary)
Slide 19
19 Site 5: high As-belt south of Amsterdam (data P. van Rossum)
Area south of Amsterdam PO4, NO3, SO4, DOC, SiO2 FeS2 FeOOH, FeS2
Fe(OH)3 CH4
Slide 20
20 Site 6: Pretreated Rhine water along an AR flow path, dunes
Zandvoort 1983
Slide 21
21 Site 7: AR with Meuse River water, near The Hague (DZH);
snapshot 2006
Slide 22
22 Redox zoning on Langerak AR pilot, after 1.5 yr injection As
in layer C (very reactive FeS 2 ) on Langerak site A B C Site 8:
DWI
Slide 23
23 Trace Elements from pyrite are largely immobilized in fresh
Fe(OH) 3 - precipitates (Stuyfzand, 2001) Fe 0.98 Co 0.003 Ni 0.01
Zn 0.01 S 2 As 0.005 + O 2 + NO 3 - + xH 4 SiO 4 Si x Fe(OH) 3 Co
0.0027 Ni 0.009 Zn 0.009 (HAsO 4 ) 0.004 +2SO 4 2- +0.001 (H 3 AsO
3 + Ni 2+ + Zn 2+ ) + N 2 + 0.0003 Co 2+ High As-concentrations if:
SO 4 high SO 4 high x or t small x or t small pH high pH high PO4
and H 4 SiO 4 high PO4 and H 4 SiO 4 high
Slide 24
24 Does ripening of ferrihydrite to goethite mobilize As?
Pumping wells often clog by mixing of Fe 2+ with O 2 /NO 3
-water
Slide 25
25 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 PO 4, SO 4, NO 3, HCO 3,
DOC, F, temp, Reducing gases, esp.CH 4 (and H 2 S) Needed / to be
studied: As behaviour in SIR and ASR systems An As risk assessment
method
Slide 26
26 Concl.3: As mobilizing processes and bias H 2 S + 4 HAsO 4
2- + 6H + 4 H 3 AsO 3 + SO 4 2- CH 4 + 4HAsO 4 2- + 8H + 4H 3 AsO 3
+ CO 2 + 2H 2 O Positive As-bias: FeS 2 / Fe(OH) 3 particles
dissolved by HNO 3 due to lack of (sufficient) filtration Negative
As-bias: filtration in lab of oxidized sample with Fe 2+
Slide 27
27 Changes in spatial distribution of groundwater types in
Neths: land recl, drainage, river endikement, Q etc.
Slide 28
28 Ni and Fe in phreatic groundwater under agricultural stress,
Vierlingsbeek (data v.Beek)
Slide 29
29 NO3 and SO4 in phreatic groundwater under agricultural
stress, Vierlingsbeek (data v.Beek) High As
Slide 30
30 Site 3: Mean composition Rhine River and 3 redox types of
River Bank Filtrate from pumping wells
Slide 31
31 Site 4: Interpreted age of Rhine bank filtrate in cross
section, in 1997-1999 Water age [year] m MSL
Slide 32
32 Mean composition of raw water from well field types in the
Neths, in 1989
Slide 33
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
