Aquatic macrophytes as bioindicators of metals in water reservoirs in Venezuela

Resumen

In Caracas, Venezuela, the water reservoirs that provide services to the city do not have a monitoring plan, and the concentrations of possible pollutants are unknown. This is of interest, considering that these areas have had uncontrolled growth and suffer from urban discharges, which are potential sources of contaminants such as heavy metals. Under this scenario, the study’s objective was to assess the potential of the aquatic macrophytes Eichhornia crassipes and Lemna minor as bioindicators for metal contamination by accumulation. Plants, water, and sediment samples were collected in La Mariposa, Camatagua, and La Pereza reservoirs, at two sampling points per reservoir, three transects per point, and three samples per transect. The concentrations of Pb, Al, Zn, Ni, Cu, and Hg in the mentioned compartments and the bioavailable fraction of sediments were determined with inductively coupled plasma in optical emission spectroscopy and a direct mercury analizer. The metal content of the analyzed samples was different between the reservoirs (pperm ˂ 0.05). Metal concentrations in E. crassipes and L. minor were also different between water reservoirs (pperm ˂ 0.05 and MC at 0.05, respectively). The plants’ metal content had a similar pattern to the concentrations of metals in water, sediments, and bioavailable fraction (p ˂ 0.05). The results suggest that both species are potential bioindicators for metal contamination by accumulation, especially E. crassipes since it is a perennial plant that could reflect environmental quality over a longer period than L. minor.