Tritium as tracer of groundwater pollution extension: case study of Andralanitra landfill site, Antananarivo–Madagascar

Abstract

This study aims to understand the extension of groundwater pollution downstream of a landfill, Andralanitra-Antananarivo-Madagascar. Twenty-one samples, composed of dug well waters, spring waters, river, and lake, were measured in stable isotopes (δ 2 H, δ 18 O) and tritium. Results showed that only two dug well waters, collected at the immediate vicinity of the landfill, have high tritium activities (22.82 TU and 10.43 TU), probably of artificial origin. Both upstream and further downstream of the landfill, tritium activities represent natural source, with values varying from 0.17 TU to 1.46 TU upstream and from 0.88 TU to 1.88 TU further downstream. Stable isotope data suggest that recharge occurs through infiltration of slightly evaporated rainfall. Using the radioactive decay equation, the calculated tracer ages related to two recent ground water samples collected down gradient of the landfill lay between [8-15] years and [4-7] years, taking into account the uncertainty of tritium measurements. For the calculation, a value of 2.36 TU was taken as A o . The latter was estimated based on similarity between stable isotope compositions of nearby spring and dug well waters as well as tritium activities of the local precipitation. Calculation of the tritium activities from the contaminated water point having 22.82 TU to further downstream using the calculated tracer ages showed values of one order of magnitude higher than the measured values. The absence of hydrological connection from the contaminated water point to further downstream the landfill would explain the lower tritium activities measured. Groundwater pollution seems to be limited to the closest proximity of the landfill.

A Review on the Application of Isotopic Techniques to Trace Groundwater Pollution Sources within Developing Countries

“…Furthermore, elevated tritium contents ranging from 14.9 to 76.6 TU (Table 2) and 10.4 to 22.8 TU (Table 3) were also observed in groundwater that was downgradient to landfills. Conversely, the monitoring of wells that are upstream and also those that are 700 m away downstream from landfills showed depleted tritium contents of 0.84 to 1.46 TU, as evidenced in Table 2 [22]. This is congruent with the study of [21] where the deep groundwater wells 5 and 6, which are farther away from the landfill had very low tritium concentrations (0 to 0.4 TU) throughout the period.…”

“…Since then, the application of environmental isotopes in groundwater and surface water studies has demonstrated their importance in terms of better understanding contaminant flow as well as in pollution source identification. Although several studies have used the isotope ratios of H and O for hydrologic and geochemical investigations, only a few applications [16,21,22], have been reported for dumpsites in developing countries.…”

“…The authors of [16,21,22] employed stable and radioactive isotopes of water to verify the migration of leachate contaminant in the water bodies of Bantar Gebang Landfill, Indonesia, Metro Manila, Philippines and Andralanitra landfill site, Madagascar, respectively. To confirm the interaction of leachate with groundwater bodies, the stable isotope compositions of the leachates and those of the monitoring wells were measured and the results are presented in Table 2 and Figure 1, respectively.…”

Multi-indicator analysis of the influence of old municipal landfill sites on the aquatic environment: case study

“…One of the drivers of this increase is landfilling, which contributes to the pollution of drinking water resources (Kjeldsen et al 2002; Lisk 1991). In addition, using landfills as a method of municipal solid waste management has a negative influence on water resources (Ramaroson et al 2018). This form of waste management is still the most commonly used solution in the world (Laner et al 2012).…”

Characterization of groundwater recharge through tritium measurements

“…or from hospital wastewaters or from biological laboratories as tritium thymidine, which is a tracer used in microbiology laboratories (Tazioli et al, 2002;Tazioli, 2011). Ramaroson et al (2018) shown the extension of groundwater pollution downstream in Madagascar using tritium and stable isotopes (δ 2 H, δ 18 O) analyses. Results showed high tritium activities probably of artificial origin.…”