Anthropogenic Activities Elevate Heavy Metals Levels in Soil and Tree Bark; A Case Study of Lower Zambezi and Mosi-Oa-Tunya National Parks

Abstract

The impact of various human activities on protected environments remains a significant concern. Mining for ores is crucial in many aspects of society. To achieve global decarbonisation, more metals are required, which will lead to increased worldwide metal exploration and mining. Zambia is primarily a mining country and has expanded exploration into protected lands (national parks). The effects of this exploration on these protected areas is ongoing. This study aimed to establish baseline data for monitoring metal pollution in the Lower Zambezi National Park before mining commenced. It also evaluated whether tourism influenced metal pollution in national parks and how these metals and metalloids correlate within tree bark and soils. To accomplish this, soil and Acacia tree bark samples were collected from Lower Zambezi National Park and Mosi-Oa-Tunya National Park. Arsenic (As), cadmium (Cd), chromium (Cr), cobalt (Co), copper (Cu), mercury (Hg), manganese (Mn), nickel (Ni), lead (Pb), and zinc (Zn) were analysed in this study. The concentrations of metals and metalloids were higher in areas with vehicular traffic and mining activity in the national parks, which may directly impact the biosystems in those areas. Maximum levels of metals in soil in these areas were as follows: As 40.8 mg/kg, Cd 0.879 mg/kg, Cr 241 mg/kg, Hg 1.1 mg/kg, Pb 211 mg/kg, and Zn 1285 mg/kg. When compared to areas of lower anthropogenic activities, differences in metal concentrations were up to 1000-fold. These changes can potentially affect the adaptation of wildlife to various stressors, especially as we are facing global climate change.