NSU Presentation 7Dec 2009 Alt

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Arsenic in tubewell water and

approaches for sustainablemitigation

Md. Jakariya



1.Global and national extent of arsenic

contamination

2. Challenges to mitigate the arsenic problem

3. Approaches for sustainable mitigation

papers

Presentation Outline



Arsenic in the Indus-Ganges-Meghna-Brahmaputra River System

Bangladesh

Primary sources of arsenic:

Himalayan and surroundingregion

Arsenic is transportedthrough the sediments bythe river Ganges-Indus (andtheir tributaries) up to the

Bengal/Indus Delta. India

Nepal

Himalaya

Pakistan



•There are 8-10 million wells;

•Approximately 30% exceeds

BDWS;

•>50% exceeds WHO guidelinevalue;

•25-30 million people are

exposed to arsenic poisoning;

•Mitigation and patient

identification are limited

considering the magnitude of

the problem.0

10

20

30

40

50

% o f T e s t e d W e l l s

< 0.01 0.01-0.05 > 0.05

Arsenic Concentrations (mg/L)

29.19 30.15

21.3612.93

65.16

23.5929.12

0

20

40

60

80

100

B A M W

S P ( 1 9 0 )

U N I C E F ( 4

5 )

W o r l d V i s

i o n ( 1 3 )

W P P ( 1

5 )

D A N I D A

( 8 )

A A N ( 0 1 )

T o t a l ( 2 7

2 )

Organizaion (No of Upazila)

% o f T e s t e d T W

Arsenic in the groundwater of the

Bengal Delta Plain (BDP)



Approaches for sustainable mitigation



Assessment of the effectiveness of field test

kit results (n=12,532) and its validation

(k=0.91, p<0.01)(k=0.92, p<0.01)Kappa test (k)

0.910.92Specificity

0.980.99Sensitivity

5.12.3False Negative (%)

3.64.4False Positive (%)

7464Prevalence (%)

WHO drinkingwater guideline

(10 µg/L)

BWDS level(50 µg/L)

Indices for validation of the

field kit results



Comparison between Merck field kit and

laboratory (AAS) results

Average 87%Average 91%12,532 (100)Total

99991253 (10)>500

99906141 (49)100-499

9870877 (7)50-99

8687 501 (4)25-49

4798376 (3)10-24

95993384 (27)0-9.9

10 µg/L level50 µg/L level

Percentage of TWs detected

correctly (%)

Total number

of TWsscreened*

Concentration

range (in µg/L)

*The values in parentheses represent the percentage of TWs in respective categories



Findings on developing testing

methodology

Merck kit could be used for mass scale As detection inTW water in Bangladesh (99% sensitivity);

As concentration between (10-24) for 10 µg/L and (50-99)

for 50 µg/L cut-off levels are mostly misclassified andneed to be reanalyzed in laboratory;

Field kit allows screening quickly in the presence of enthusiastic crowd, which helps to raise people’s

awareness about the As problem;

In order to reduce false identification severalprecautionary measures (eg. proper training, temp.humidity etc.) need to be ensured.



Approach II:

Identify sustainable mitigation option (s)



Problems encountered by users of

different alternative safe water options

Option Water source Major disadvantages

PSF Surface Many ponds used for fish-culture with use of poison to kill

predator fishes. High initial load of bacteria in pond waters.Acceptability not universal.

RWH Rainwater Rains not uniformly abundant in all areas; There is little or

no rain in dry season. Prohibitive cost for poor households.

Arsenicremoval

filters

Arsenic-contaminated

groundwater

Effectiveness in removing arsenic questionable,Unaffordable, Disposal of sludge is environmentally

problematic, Expensive and thus less sustainable on a long-

term basis particularly for poorer households.

Dugwell Sub-surface Susceptible to bacteriological contamination, May dry up

during winter, Presence of manganese, iron, and arsenic in

some wells.Deep

wells

Deep aquifer

(>250m)

More expensive than tubewells; Some uncertainties as a

long-term source for arsenic-safe water.

Piped

water

Deep aquifer

or treated

surface water

Expensive for country-wide adoption, Requires organization

to run.



71

95

85

100

67

0 10 20 30 40 50 60 70 80 90 100

Dugwells (231)

PSF (37)

RWH (90)

Arsenic removal filters

(10,569)

Bishudhya Filters (30)

Active Inactive

%

0

17

80

100

10

0 10 20 30 40 50 60 70 80 90 100

Re-installation of TWs (60)

PSF (23)

RWH (147)

Arsenic removal filters (10,569)

Bishudhya Filters (210)

Active Inactive%

Functional stautus of

different alternative

safe water options

(revised in 2004)

a) Sonargaon & Jhikargachha

upazilas (1999-2004)

b) Matlab upazila (2001-2004)

b)

a)



Findings on identifying sustainable

options

Less than 2% of the total provided options werefound to be in operation;

Instead, two new peoples’ driven initiative

emerged: Preferred use of arsenic safe tubewells;

Reinstallation of tubewells below 55-100mdepth instead of previous common depth of

20-30m. Identification of sustainable alternative safe

water options might be still needed for areaswhere none of the above methods would beapplicable.



Objective III:

Validate a people’s driven initiative for

sustainable source of drinking water



Litholog based on local driller



Prediction of risk for high

arsenic groundwater

REDOFF-

WHITE

WHITEBLACK

RISK

High Neglible?

REDOX

Very reduced Less reduced



Classification of samples: local

drillers vs. Munsel colour code

a) Black b) White

c) Red d) Off-white

Black White Off-White Red

Sediment colour

0.0

80.0

160.0

240.0

320.0

400.0

Asug/l

Astot

Black White Off-White Red

Sediment colour

0.0

4.0

8.0

12.0

16.0

20.0

Fetot



Geological cross section of the aquifers



There were minor discrepancies between thedriller’s colour classification of the sedimentsand the Munsell description;

The chemical characteristics of thegroundwater correlate well with the colour of the aquifer sediments;

Through the use of the technical knowledge of local drillers, it may be possible to obtain safewater in many parts of Bangladesh.

Findings on validating peoples’ driven

initiative



Summary conclusions

Identified the method of field testing kit for screening and monitoring of As-contaminatedTWs;

The safe water options need to be identified

considering the geo-physical and socio-culturalaspects of the people of the respective villages;

Detailed scientific investigation needs to becarried out to validate local drillers initiative (i.e.

re-installation of TWs at targetted depths).



Thanks for your attention



Safe water coverage and the climate change issues



Jakariya M, Vahter M, Rahman M, Wahed MA, Hore SK, Bhattacharya

P, Jacks G, Persson LA.. Screening of arsenic in tubewell water with

field test kits: Evaluation of the method from public health perspective.

Sci Total Environ, 2007, Vol. 379(2-3):167-75;

Jakariya M, von Bromssen M, Jacks G, Chowdhury AMR, Ahmed KM,

Bhattacharya P. Searching for a sustainable arsenic mitigation strategy

in Bangladesh: experience from two upazilas. Int. J. Environment and

Pollution, 2007, Vol. 31, Nos. 3/4: 415-430;

von Bromssen M, Jakariya M, Bhattacharya P, Ahmed KM, Hasan MA,

Sracek O, Jonsson L, Lundell L, Jacks G. Targeting low-arsenic

aquifers in Matlab Upazila, Southeastern Bangladesh. Sci Total

Environ, 2007, Vol. 379 (2-3):121-32.

Papers



Controls on

Arsenic

Occurrences:

Depth/Sub-surface

Geology



Deep Tubewell (DTW)



Rain Water Harvester (RWH)



Pond Sand Filter (PSF)



Rural piped water system



Improved Dugwell



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V31

V60

V32

V61V62

D00

V10

V72

V11

W00

KM

.8.6.4.20

GIS unit, ICD DR,B

E



Source: Peter Ravenscroft

Arsenic Concentration at

different cut-off levels



Interpretation of kappa results :

Value of κ Strength of agreement

≤0.20 Poor

0.21 - 0.40 Fair

0.41-0.60 Moderate

0.61-0.80 Good

0.81-1.00 Very good

The kappa (κ) test is a test of agreement between two parameters-

e.g. between lab and field kit results in this particular case



Colour scale of Merck sensitive arsenic filed testing kit



Matlab Study Area



Alcan Filter

Arsenic Concentration change over time



Arsenic Concentration change over time

(Laboratory analysis)

n=246 (Feb 1999- Sep 2001)

3.7

46.749.6

0

10

20

30

40

50

60

%

N h C t ti i d C t ti d d

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