Correlation Between Surfactants and Heavy Metals in a Natural Lake

Abstract

There is some concern that when heavy metals and surfactants exist together in the environment, the surfactants will affect the transport and fate of the heavy metals. This study was conducted to determine the presence of surfactants and heavy metals in a natural lake's surface microlayer and in rainwater from seven locations in the Lake Chini area in Malaysia. Colorimetric analysis was used to determine the concentration of anionic surfactants as methylene blue active substances (MBAS) and cationic surfactants as disulphine blue active substances (DBAS). Inductively coupled plasma mass spectrometry was used to determine the concentration of heavy metals such as Cu, Pb, Zn, Fe, Cd, and Ni. The results indicated that the average concentrations of MBAS and DBAS in the lake's surface microlayer were higher in the dry season (0.27 ± 0.06 and 0.22 ± 0.02 μmol L−1) than in the wet season (0.22 ± 0.03 and 0.19 ± 0.02 μmol L−1). The average concentrations of MBAS and DBAS in rainwater were 0.21 ± 0.02 μmol L−1 and 0.18 ± 0.02 μmol L−1, respectively. Surfactants in the lake's surface microlayer were found to be positively correlated with Pb, Cd, Zn (p < 0.01) and with Ni (p < 0.05). These findings have implications when evaluating fate & transport of metals in the presence of surfactants that could be useful in environmental forensic investigations.