The following tasks are being undertaken in the second phase of the project. Detailed web pages from Phase 2 of the project are now available.
Monitoring: new observation boreholes
A set of nested piezometers is being installed in each of the three Special study areas (Chapai Nawabganj and the sadar thanas of Faridpur and Lakshmipur) in order to monitor the variation of the arsenic concentration with depth and time. Separate piezometers are being drilled to depths of 5 m, 10 m, 20 m, 30 m , 40 m and 50 m (where possible) with screen placed at the bottom of each borehole. A selection of other solutes will also be monitored. In addition, a single deep cored borehole will be drilled to about 150 m in each thana in order to obtain sediment core and to enable the deep aquifer to be sampled.
Further work in the special study areas
A further round of groundwater sampling will be undertaken in the three special study areas to fill in gaps in knowledge (e.g. the extent of the Chapai Nawabganj hotspot). More detailed trace metal analyses will be undertaken by ICP-MS to establish if there are any other potential water-quality problems.
Monitoring: the BWDB water quality network
The Bangladesh Water Development Board has maintained a network of water quality monitoring sites throughout Bangladesh. These will be sampled for arsenic and other solutes.
Sediment chemistry and mineralogy
The interaction of the sediments with the groundwater is a key aspect of the arsenic problem that is not well understood. This needs to be deterined in order to predict the rate of movement of arsenic in the aquifer and how it might change with time. Sediment will be obtained from the newly-drilled holes (above) and from existing core material and characterised by various methods.
Sedimentology and hydrogeology
Additional work will be carried out in collating borehole logs of the sediments, defining sedimentological variations and in modelling water and solute movement.
Other work
Plans have been made to carry out further studies, but these have not yet been finalised. These studies include: the survey of the northern part of Bangladesh not sampled in Phase 1; the monitoring of DPHE test deep boreholes for arsenic to establish reliable baseline data for the deep aquifer and a more complete analysis of the entire collection of regional survey samples.
Approximately one in eight or 253 of the samples collected in the regional survey was subject to multielement chemical analysis by ICP-AES. This will be extended to all of the samples and will enable a comprehensive geochemical atlas of Bangladesh groundwaters to be made. The resulting data will be analyzed using both classical and geostatistical methods.
A typical village hand pump
