Arsenic contamination mapping in Gazna | 2017

My name is Ricarda, I studied environmental engineering at Technical University of Denmark (DTU) and for my Master Thesis Project I worked together with UBU and the local Indian NGO KTT on a project dealing with arsenic contamination of groundwater.

During the project I stayed in the village Gazna in West Bengal, India for one month in April 2017. Gazna is a village located in a rural area where the main source for drinking water is untreated groundwater being withdrawn by hand pumped tube wells.

Unfortunately, most of the groundwater is strongly contaminated with arsenic, which occurs naturally in the ground and can lead to chronic arsenic poisoning. Additionally, the arsenic distribution is very heterogeneous, meaning that highly arsenic contaminated groundwater occurs just next to arsenic free groundwater. This makes the problem very complex.

The aim of my project was to create preliminary maps, showing the arsenic distribution in the area of the village and to investigate on processes affecting arsenic mobilization to groundwater, mainly following the theory that arsenic release might be linked to humic-like, organic, compounds present in the water.

Before my journey to India, I received all the data from arsenic measurements that were previously taken by the UBU and KTT. Based on this data, I created preliminary maps in ArcGIS showing the arsenic distribution at different levels of depth in the different aquifers underlying the village.

Once I arrived in Gazna, I met Dampy and Basudev, the two technical workers of the local NGO. Together, we carried out fieldwork to collect additional arsenic measurement with the so called arsenator, an in-field measurement tool. Our work required to measure the private tube wells located in people’s houses and in their agricultural fields.

Dampy and Basudev were super friendly, helping to translate and showing me around the village and soon I became good friends, not only with them, but also the family who hosted me during my stay. During a lot of evenings we were sitting together playing music, singing or playing cards.

Nevertheless, the fieldwork in the village was also challenging at some times. For example, information about the aquifer structure and hydrology in the area is very limited and no borehole data was available to collect geochemical information. Luckily, everyone in the village was extremely nice and supported us, to collect as much information as possible. For example, I could carry out several interviews with local drillers, to gather information about sediment types, and even watch a drilling process for installing a shallow tube well. During the last days of the field work we collected a lot of water samples, which I took back to Denmark. Back home my task was to analyse the water samples in the lab at DTU and indeed we found indications for a possible link between arsenic concentration and humic-like substances.

Overall, the time in Gazna was a great experience. Everyone was very welcoming and nice and I felt at home in the village already after a very short time. I even came in the right month to celebrate Bengali New Year. Seeing people singing in the streets and watching the traditional New Years rituals of the monks was absolutely amazing and an unforgettable experience!