Heavy metals like Pb, Cd, Hg, As, Se and Zn are categorized as first class of hazard. The sources of heavy metals are industrial sources including present and former mining activities, foundries and smelters and diffuse sources such as combustion by products and traffic fumes. Most of the heavy metals are essential to plant and animal growth as trace elements in order to maintain biological functions (Pam & Brian, 2007). This has mad them to be environmentally significant. Heavy metals can be abundance in some soils and environments where they sometimes occur in rocks or are concentrated by natural
There have been numerous reports of histopathological changes in the liver and kidney of the fish exposed to a wide range of heavy metals and organic compounds (Abdel, 2012). Impact of contaminants and toxicity of heavy metals in aquatic ecosystem can be evaluated by measuring physiological and biochemical parameters in the kidney and liver of the fish (Barhoumi et al., 2012). In comparison to the terrestrial life, aquatic organisms are more sensitive to the exposure and toxicity of heavy metals, therefore, they provide the accurate data to analyze the lethal effects such as, mutagenicity and oxidative stress caused by environmental pollutants (Vosyliene and Jankaite, 2006). Oxidative stress is a difference between the rate of production of reactive oxygen species and antioxidant defense system of the aquatic organisms (Nishida,
Other source can include unsafe or excess application of pesticides, fungicides and fertilisers (Zhen-Guo et al., 2002). Additional potential sources of heavy metals include irrigation water contaminated by sewage and industrial effluent leading to contaminated soils and vegetables (Bridge
It is soluble in hexafluroisopropanol, hexafluroacetone and chloroalcohols. Whereas, chitosan is deacetylated product of chitin, is soluble in acetic acid and formic acid. The nitrogen content of chitin is mostly acetylated group, whereas, nitrogen in chitosan is mostly in the form of primary aliphatic amino group. Preparative procedure of chitin and chitosan are shown in Fig, 2 (a) Chitin and chitosan are excellent functional materials for biomedical applications because of their high biocompatibility, biodegradability, antibacterial activity, non-antigenicity and high adsorption properties that makes them appropriate for tissue engineering (Fig. 2 (b))[15-18].
Heavy metals can be found in different products through natural and anthropogenic processes, and contamination can originate from various sources (Gall, Boyd, & Rajakuna, 2015). Contamination in agriculture could be from the soil, water and irrigation methods used. In hot dry season, the wastewater used to irrigate the crops in Zambian farms in East Africa were found to contain above acceptable levels of chromium and copper, and during the dry season, copper, chromium, nickel and cobalt in likewise considerably high amounts were identified. It was inferred that the large amounts of heavy metal in the soil were probably due to the seepage of water from the dams nearby the sample area and natural copper content of the soils because of the close
Contamination with trace metals has become a great concern around the world, especially in developing countries including India (Alagarsamy, 2006). With the rapid industrialization and economic development in coastal region, these metals are to be introduced to aquatic environment (Feng et al., 2004; Romano et al., 2004). Contaminated marine sediments have been recognized as a very important deposit for persistent toxic substances (heavy metals and xenobiotic organic compounds) released into the aquatic environment from various sources. Identification of the natural and anthropogenic sources of heavy metals is an important task in marine pollution research (Esen et al., 2010). Previous studies have shown that human exposure to a high concentration
Once mercury reaches a resting place, it cannot be moved easily. Sediments on the floor of San Francisco Bay remain contaminated with mercury because of the California gold rush of the 19th century. Mercury is extremely harmful to human health. The amount of vapor released by mining activities is proven to damage the kidneys, liver, brain, heart, lungs, colon, and immune system. Continued exposure to mercury may cause fatigue, weight loss, tremors, and shifts in
However, due to natural causes but mainly pollution, the concentration of the trace elements (also considered to be heavy metals) in the soil has been increased thereby leading to heavy metal pollution. The heavy metal pollution not only affect the soil and plants, but also human
Water pollution caused by heavy metals is a global problem. The discharge of toxic metals into the ecosystem may severely affect the biotic as well as abiotic components of the environment. These metals are generally derived from different industrial activities such as mining, metal finishing, battery manufacturing, electroplating, etc. and are responsible for contaminating the receiving water bodies even when present in trace amounts. This is due to their carcinogenic and toxic properties (ATSDR, 2013).
Among these, industries are creating a wide spread of pollution to the environment, especially the increased levels of heavy metals such as cadmium, lead, cobalt and mercury in to the soil and aquatic system; these heavy metals have highly hazardous and toxic nature which can affect the human health and living things. Generally, living systems near the industries would consume such heavy metal toxicity in