1. Sources of Groundwater Contamination Designed discharges On-site wastewater disposal Injection wells Land application Storage, treatment and disposal **Landfill Open dumps Residential disposal Surface impoundments Waste tailings Waste piles Material stockpiles Graveyards Animal burial Aboveground storage tanks *Underground storage tanks Containers Open burning and detonation Radioactive disposal Transport and transmission Pipelines Materials transport Activities with incidental releases Irrigation Pesticide application Fertilizer application Animal feeding operations De-icing salt application Urban runoff Atmospheric deposition *Mining and mine drainage Activities altering flow patterns Oil and gas production wells Other wells Excavation Natural sources Surface-water interaction **Natural leaching Salt-water intrusion

2. Mine Tailings/AMD

3. Vineland Chemical

4. Leaking Underground Storage Tanks Source: U.S. Environmental Protection Agency, August 7, 2002. Office of Underground Storage Tanks (OUST). U.S. Environmental Protection Agency. Washington D.C. www.epa.gov/swerust1/graphics/ miscpix1.htm. Accessed January 28, 2003.

5. Oxidation and Reduction Capacities From Christensen et al, Applied Geochemistry 16(2001).

6. Vertical Figures

7. 2 Regions at Winthrop Landfill

8. Dissolved Species mean, mg L -1 DOCCl - SulfideFe 2+ IronBODCODArsenic Central Region26  14 29  6 53  49 24  15 37  9 8383 35  23 0.3  0.1 Peripheral Region16  4 10  2 5252 2424 2424 6060 1010 0.01  0.005 2 Regions at Winthrop Landfill

9. The animated maps that follow show the probability of arsenic exceeding various concentration thresholds in wells of any depth. The maps automatically progress through thresholds of 10, 50, 200 and 400 ppb. Exceedance of Arsenic Concentration Thresholds Click to continue http://www.es.ucl.ac.uk/research/lag/as/index.htm As in Bangladesh

10. Profiles in a Bangladesh Well From Harvey et al, Science 298 pp. 1602-1606.