**4. Effects of heavy metals on ecosystem**

Most often found in greater concentrations in abattoir waste, heavy metals are hazardous to soils, plants, aquatic life, and human health. To exert their toxicity towards soil biota, heavy metals interfere with vital microbial processes, leading to a decrease in both the diversity and activity of soil microorganisms. The uptake of heavy metals by plants can be inhibited at low quantities, which can lead to their accumulation along the food chain and a possible threat to the health of animals and humans. However, at the level of aquatic systems, contaminants such as heavy metals encourage the creation of reactive oxygen species (ROS), which may harm fishes and other aquatic creatures.
