Chapter 6 - Other trace elements (heavy metals) and chemicals in aquatic environments

Abstract

Industrial, sewage, and agricultural wastes are discharged daily into the aquatic ecosystem. Heavy metal ions such as mercury, lead, cadmium, arsenic, chromium, and selenium are naturally or anthropogenic are released into the environment through human activities. Heavy metals causing many problems and they are a major threat to human health. Trace elements are any element having an average concentration of less than about 100 parts per million atoms (ppma) or less than 100µg/g. This group of pollutants is widely found in water, wastewater, seafood, personal care products, and human samples. Exposure to heavy metals can cause toxicity to a variety of tissues, organs, and systems such as circulatory, respiratory, endocrine, immune, nervous, urinary, and reproductive systems. The main mechanism of heavy metals toxicity are the generation of free radicals to cause oxidative stress, damage of biological molecules such as enzymes, proteins, lipids, and nucleic acids, damage of DNA which is key to carcinogenesis as well as neurotoxicity. Some of the heavy metals toxicity could be acute while others could be chronic after long term exposure so there are various stages and technologies for water purification. Primary, secondary, and tertiary treatment processes are the stages of urban and industrial water treatment.