Program: Collaborative Research for Common Regional Issues (CRC)

Field: Geological and Geo-Resource Engineering

Principal Investigator: Dr. DANG Thuong Huyen

Sending University: Ho Chi Minh City University of Technology (HCMUT)

Japanese Co-Investigator: Prof. Dr. Toshifumi IGARASHI

Japanese University: Hokkaido University

Year: 2016


Arsenicals, in varying concentrations, are natural in the environment. The arsenical form is dependent upon pH, Eh, organic matter content, adsorption to solid matrices and the presence of other substances, such as iron and magnesium. In the Mekong delta, there are two layers of soil that produces the abundance of arsenic and are the primary natural causes of arsenicals in soil and groundwater (Berg, et al., 2006). The Pleistocene sediment layer lies underneath the Holocene sediment layer and is rich in organic matter, has a low pH, and a lot of acid sulfate and pyrite, creating it a favorable reducing condition to release arsenic from the Holocene sediment (Nguyen and Itoi, 2008).The researches about arsenic contamination in groundwater in the Mekong Delta provided the exposed of arsenic in groundwater (Berg et al., 2001, 2008; Hoang et al., 2010; O’Neill et al., 2013; Merola et al., 2015) and process of arsenic may release to groundwater in upper the Mekong Delta in Cambodia (Buschmann et al.,2007, 2008; Hery et al., 2008; Kocar et al., 2008; Lear et al., 2007;Papacostas et al., 2008; Polya et al., 2005, 2008; Rowland et al.,2007, 2008; Van Dongen et al., 2008) and lack of data in Vietnam area (Nguyen and Itoi, 2008). However, researches have not yet mentioned in detail about the change of arsenic in seasons and spatial of the Mekong delta.
Therefore, the purpose of this study are to:
1) Investigate arsenic concentration in Dong Thap province, An Giang Province (Vietnam) and Kandal Province (Cambodia). The results of investigation will be used to assess the effects of season on arsenic concentration in groundwater and arsenic distribution from the upstream to downstream of the Mekong Delta. Other hazardous elements will be also monitored such as manganese (Mn), Boron (B), Barium (Ba), Selenium (Se) and Iron (Fe). These four inorganic compounds have not been studied in detail yet. Consideration of contamination of these elements is important in the study. The relationship of As and those elements will be investigated.
2) Investigate the geochemical conditions and its change in the research area. The change will be depicted from the upstream to the downstream of the Mekong delta.
3) Clarify the geochemical factors affecting on the arsenic release to groundwater. Geochemical indicators will be monitored to assess effects of environment on arsenic precipitation and release in the Mekong Delta. The relationship between arsenic distribution and geochemical conditions during sedimentation process will be identified in this study. The arsenical form is dependent upon pH, ORP, organic matter content, adsorption to solid matrices and the presence of other substances. Thus, examination of mineral composition of soil in the Mekong delta is required.
4) Develop reactive transport and risk assessment model. The results of this model will provide spatial distribution of arsenic-contaminated groundwater, maps of potential areas highly at risks of arsenic-contaminated groundwater and possible large-scale mitigation approaches for this serious problem. This map is important for local governments in order to manage groundwater resources.
5) Do experiment to treat arsenic in groundwater with simple method so that poor local people are easy to apply at their home. (Source: Application to CRC 2016)