Heavy Metals in Surface Soils and Crops

In the era of industrialization and technological progress, pollution has reduced the quality of life for humans. Heavy metal pollution is one of the main causes of environmental degradation. The underlying causes are natural as well as human. Heavy metal contamination of soil has become a worldwide environmental issue that has attracted considerable public attention, mainly due to increased concern for the safety of agricultural products. Heavy metals refer to some metals and metals with biological toxicity such as cadmium, mercury, arsenic, lead and chromium. These elements enter the soil agricultural ecosystem through natural processes resulting from raw materials and through human activities. Heavy metal pollution is a great threat to the health and well-being of animals and humans due to the risk of potential accumulation through the food chain. The main sources of heavy metal pollution are air pollution, river sediments, sewage sludge and municipal waste compost, agricultural chemicals such as fertilizers and pesticides, and industrial wastes such as factories that release chemicals. Heavy metals can enter the water supply through industrial and consumer wastes or even from acid rain that decomposes soils and releases heavy metals into streams, lakes, rivers and groundwater.