Many heavy metals are toxic to humans and animals, and constitute a major cause of environmental pollutions. Levels of heavy metals in the environment are on the rise, which is resulted from both human activities, such as urbanization and industrialization, and natural processes, such as volcanic eruptions and weathering of mineral deposits. Nowadays, approximately 235 million hectares of land around the world are polluted with heavy metals. Heavy metal pollution is posing a serious risk to ecosystems and human health due to contaminations in the food chain. Traditionally, physical, chemical, and microbial methods have been used to clean up contaminated soils. However, these conventional soil-remediation techniques are often costly, take a long time to complete, and sometimes impose additional health and environmental hazards. In contrast, the more recently developed phytoremediation methods, in which green plants are used to decontaminate the environment, are cost-effective and cause less disruption of the ecosystems.
The objectives of this writing assignment are to raise awareness of serious environmental issues and explore the possibility of using plants for soil cleanups. You are expected to do library research on the selected topic and integrate your writing with reading and critical thinking. Assignment An abandoned 200-acre land in Yolo County, California, has been contaminated with heavy metals. This land was previously occupied by a chemical manufacturing plant. The Yolo county officials are interested in redeveloping the land for commercial farming or business operations. In order to reuse a formerly contaminated site, cleanup procedures need to be carried out and the public health and safety standards developed by the Environmental Protection Agency (EPA) need to be met. The county is running on a tight budget. Funding for the remediation project is very limited. Therefore, an economic and effective decontamination method is preferred. As an experienced EPA compliance consultant, you were asked by the county officials to evaluate the status of heavy metal contaminations at the site and make recommendations on the remediation method. Your findings and recommendations will be summarized in a paper, which will be discussed at the countys next business meeting. You collected some soil samples from the contaminated site and determined that cadmium (Cd) and cobalt (Co) were the major heavy metal contaminants in the soils. In your report (i.e. paper) to the Yolo county officials, you plan to include:
1) A brief introduction of the commonly used soil remediation methods,
2) Your recommendation of a phytoremediation approach for soil decontamination (You will discuss both the advantages and limitations of the phytoremediation method), and
3) Your suggestion of two plant species (one for each heavy metal identified) that are suitable for cleaning up the heavy metal contaminants. These plants will be selected based on the heavy metals that are present in the contaminated soil (cadmium and cobalt) and the characteristics of these plants (i.e. what type of heavy metals can these plants take up and accumulate?).
4) Because the phytoremediation method is relatively new, it is not well understood by the general public. Some of the concerns include i) Is the phytoremediation method safe to the public? and ii) What do we do with the plants after they have taken up the heavy metal contaminants? You will address these concerns in your paper as well.
