Use of Biomphalaria glabrata as a bioindicator of groundwater quality under the influence of NORM

Abstract

The Brazilian northeast is known to have sedimentary areas that contain minerals with anomalous concentrations of naturally occurring radioactive material (NORM). This characteristic can contribute to the elevation of natural radiation in the air, soil, and groundwater. Due to the inefficiency of drinking water distribution in this region, the use of water from wells has become essential for the population. Therefore, the objective of this research was to monitor the concentration of 238U and 232Th associated with biomonitoring with the species of mollusc Biomphalaria glabrata in waters of residential artesian wells, used for domestic consumption, in the municipalities of Abreu e Lima and São José do Sabugi, Brazil. To check the concentration of 238U and 232Th, ICP-MS was used. For biomonitoring, ecotoxicity techniques such as embryotoxicity and genotoxicity were used. The monitoring results confirmed high concentrations of natural uranium in one of the residential artesian wells, the data being above the limit allowed by the Ministry of Health of Brazil, whose study reference is the World Health Organization (WHO). The results of the bioassays showed embryotoxicity, with malformations and deaths in the exposed organisms being observed. The comet assay showed that groundwater caused changes in the mollusc's DNA, indicating genotoxicity. The bioassays suggest that embryotoxicity and genotoxicity were caused mainly by the high concentration of natural uranium. Therefore, the bioindicator B. glabrata was shown to be sensitive to the toxic effects of anomalous concentrations of NORM present in groundwater.