Phytoremediation of Heavy Metals

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TABLE OF CONTENTS

CHAPTER 2: LITERATURE REVIEW1

Heavy metals background1

Methods used for remediation3

Phytoremediation technique4

Bio-augmentation6

Bio-Stimulation6

Basics of Phytoremediation Process7

Phytoremediation of Heavy Metals8

Description of Heavy metals10

Criteria used for phytoremediation12

Selection of Species12

Interspecific Plant Interactions13

Populations Variation14

REFERENCES16

CHAPTER 2: LITERATURE REVIEW

Heavy metals background

The advocates of environment protection fight for an environment that is free from harmful contamination. The demands for economic and industrial development outweigh the demands for environmental protectionists. The industrial development is often associated with the contamination of the natural environment. The beginning of industrial revolution has resulted in the contamination of natural sources. Since 1990 AD, the emissions of heavy metals account for 90% of emissions. It is now widely recognized that the activities of human beings lead towards the accumulation of heavy metals in soil. The exposure to heavy metals comes from different sources. The most significant source is industrial activity. The industrial activities such as mining, smelting, and refining are the major sources of soil contamination. The discharge of heavy metals and other industrial waste have also resulted in the contamination of water bodies. The heavy metals and other toxic substances also have an impact on living organisms involved in food chain. The major environmental pollutants include heavy metals such as cadmium, copper, lead, zinc, and others. A majority of heavy metals are disposed in the soil; therefore, it is important to develop and implement methods that deal with this problem. The conventional methods used for remediation are expensive and not environmental friendly (Dembitsky, 2003, pp. 1177).

Heavy metals are considered to be the major source of toxicities around the world. According to ENS (2006), there are many cases of the toxicity issues associated with heavy metals. The polluted places are a threat to the health of people living near such areas. Mining is an important economic activity in many countries such as Brazil, India, China, and Peru. The mining of precious metals contribute towards a large portion of heavy metals. The largest producer of Iron core is China, while the larger producer of copper is Chile. In Mexico, the largest proportion of silver is produced. There are a number of chemicals and heavy metals that are discharged into the bodies of coastal waster. When toxic substances are released into the environment, a variety of toxic effects are observed (Dembitsky, 2003, pp. 1179). Heavy metals are considered to be hazardous because they have a significant impact on the natural food chain. There are some heavy metals which are highly toxic in nature such as Hg, Cd, Co, and others. The presence of such elements in the atmosphere is extremely harmful for the environment. The bio-accumulation of heavy metals in food chains is highly dangerous for human health. Ingestion is considered to be the most common route of human exposure to heavy metals. Heavy metal contamination occurs from geological and anthropogenic activities. The sources include smelting process, small-scale industries, and others.

The concentration of heavy metals is also known as green solution. Phytoremediation has become a subject of public and scientific ...