Đang chuẩn bị liên kết để tải về tài liệu:
Lecture Marine environmental studies - Topic: Major marine pollutants - Metals

After studying this chapter you will be able to understand: Almost all natural metals can be found in seawater; metals can be toxic if they are present in excess; metals are needed in small quantities for the essential growth of organisms; other metals have no known use; incidentally, most of the metallic pollutants are the non essential ones. | MAJOR MARINE POLLUTANTS METALS Almost all natural metals can be found in seawater. Metals can be toxic if they are present in excess. Metals are needed in small quantities for the essential growth of organisms. Other metals have no known use. Incidentally, most of the metallic pollutants are the non essential ones. 1 MERCURY (1) It is probably the most serious metallic pollutant. It occurs in two forms: Inorganic Organic The organic is more toxic than the inorganic mercury In oxygenated marine sediments, bacteria can convert the less toxic inorganic mercury to more toxic organic mercury Organic – natural and can be broken down by the environment Inorganic – synthetic mercury (synthesized in labs) and released into the marine environment 2 Mercury continued Mercury is mobile in the marine environment and can therefore get accumulated in fish and in other marine organisms. Eating seafood or any other food containing 0.3mg/day of mercury over an extended period can lead to the onset of: | MAJOR MARINE POLLUTANTS METALS Almost all natural metals can be found in seawater. Metals can be toxic if they are present in excess. Metals are needed in small quantities for the essential growth of organisms. Other metals have no known use. Incidentally, most of the metallic pollutants are the non essential ones. 1 MERCURY (1) It is probably the most serious metallic pollutant. It occurs in two forms: Inorganic Organic The organic is more toxic than the inorganic mercury In oxygenated marine sediments, bacteria can convert the less toxic inorganic mercury to more toxic organic mercury Organic – natural and can be broken down by the environment Inorganic – synthetic mercury (synthesized in labs) and released into the marine environment 2 Mercury continued Mercury is mobile in the marine environment and can therefore get accumulated in fish and in other marine organisms. Eating seafood or any other food containing 0.3mg/day of mercury over an extended period can lead to the onset of: MINAMATA DISEASE (Mercury Poisoning) This disease was discovered in the Minimata Bay in Japan. 3 Symptoms of MINAMATA Mental Disturbance Ataxia Impairment of gait, speech and hearing Ataxia: lack of muscle control: the inability to coordinate the movements of muscles Gait – inability to walk normally/straight 4 CADMIUM (2) This causes the disease called “itai – itai” This disease is characterized by brittle bones and considerable pain It was discovered after the second world war in Japan. Itai stands for “ouch!” in Japanese 5 TIN Tin can be found in anti-fouling paints (although banned). Tin has been found to be harmful to marine organisms For instance, it causes IMPOSEX in marine snails and SHELL DEFORMATION in oysters. Anti-fouling paints are used to reduce growth on the hull of ships. Imposex – causing the organism to have two sexual organs – both male and female 6 LEAD Lead basically affects the growth and development of children. In the past, at the Mersey River estuary, lead .