[As] – a global problem http://www.bgs.ac.uk/arsenic/Bangladesh/ BGS and DPHE (2001) http://www.bgs.ac.uk/arsenic/Bangladesh/

As drinking water standards World Health Organization (WHO) guideline: 10 mg/L US standard 10 mg/L Bangladesh standard for drinking water: 50 mg/L Range in Bangladesh: <1 to over 1000 mg/L

* * Q ~ 1000 km3/y Araihazar Dhaka Source: M. Steckler, LDEO, based on GTOPO30 digital elevation model (USGS EROS Data Center).

Araihazar Bangladesh Arsenic Mitigation and Water Supply Program

http://superfund.ciesin.columbia.edu/home.html http://superfund.ciesin.columbia.edu/niehsWeb/

Sampling and interviews at 6000 wells: 2000/2001

Satellite image: Araihazar, one of 464 thanas in Bangladesh Population 300,000; 170 km2 (density 1800/km2) Sources: C. Small, LDEO, Landsat 7 image from USGS EROS Data Center, Sioux Falls, SD, 1991 National Census.

Depth distribution of arsenic in Araihazar tube wells 44 43 164 87 52 27 11 8

Existing wells Alternative sources Remediation options Existing wells Alternative sources New wells Surface water As removal Well switching Shallow wells Deep wells Pond water Rain collection Safi filter @$18 3-kolshi filter @$5 Tube well sand filter Maintenance Monitoring Bacterial growth Spatial variability Social resistance Dug wells Seasonality Pathogens $50 for 150 ft Installation Distribution Pond sand filter 50 families @$16 ea. Bacteria 1/100 Aquaculture Boiling Rainwater harverster 1 family @ $160/$40 ea. Storage-seasonality

Results of 5000 well study: well switching? Histogram of number of wells as a function of distance from each well to the nearest safe well, shown in increments of 50 m. The proportion of wells shown as green dots in Fig. 1 is shown at a distance of <0 m. Also shown is the cumulative proportion of tubes wells within each distance interval The proliferation of tube wells in Araihazar. Only a fraction of the wells installed in the year 2000 were surveyed. A. van Geen et al., 2001

Xiaoguang Meng – Stevens Tech. Filters? 20 L-bucket sand filter Xiaoguang Meng – Stevens Tech. As co-precipitation with ~ 20 mg/L Fe Competition of phosphate and silicate FeCl3 and NaClO addition 3” sand layer for filtration Gravity flow 1.5 to 0.5 L/hour Cleaning of sand twice a week Initial cost $7/family Reagents $4/year

Deep wells? t years kyears

Urinary creatinine-adjusted arsenic (μg/g creatinine) Some success! Urinary creatinine-adjusted arsenic (μg/g creatinine) Baseline well [As] N 1579 1477 1413 1503 1590

Domestic use As As

Domestic use As As

irrigation Domestic use As As

irrigation Domestic use As As

irrigation Domestic use As As As As

irrigation Domestic use As As As As As

Leakage along well casing irrigation Domestic use As As As As

Leakage through broken casing irrigation Domestic use As As As As