Abstract
Heavy metals and pesticides are major environmental pollutants that endanger ecosystems. The Lower Zambezi National Park (LZNP), which is home to African savanna elephants and diverse wildlife, faces increasing anthropogenic pressure from a copper mining project licensed in 2021. Even though the license has been revoked, whether mining will resume remains unclear. Elephants eat a variety of plants, have a long migration distance, and have a long lifespan; therefore, they can be significantly affected by the variety and long-term exposure to pollutants and serve as bioindicators of environmental contamination.
Elephant fecal samples were collected from two sites within the LZNP: the Lower Zambezi Eastern Site (LZES) in 2022 and the Lower Zambezi Western Site (LZWS) in 2023. Tree bark and soil samples were taken for comparison at each site. Inductively coupled plasma mass spectrometry was used to measure the concentrations of chromium (Cr), cadmium (Cd), lead (Pb), arsenic (As), copper (Cu), cobalt (Co), nickel (Ni), and zinc (Zn). Liquid chromatography–tandem mass spectrometry (LC–MS/MS) and gas chromatography–tandem mass spectrometry (GC–MS/MS) were used to screen for pesticides.
The fecal metal profiles differed by site. The concentrations of Pb, Co, Ni, and Cd varied significantly between sites, with Ni being relatively higher in LZWS and Co, Cu, and Pb being higher in LZES. While LZES is located closer to areas connected to previous and planned mining activities, LZWS experiences a heavier tourism. Low levels of pesticide residues were detected in environmental samples (tree bark and soil), and both GC–MS/MS and LC–MS/MS platforms consistently identified carbamate propoxur, which is used for malaria control, in LZWS, suggesting regional exposure. Overall, these findings reveal measurable contamination within a nationally protected area and highlight the potential of elephant feces as a practical, non-invasive bioindicator for monitoring environmental contaminants in wildlife habitats.
