tailieunhanh - Handbook of Plant Nutrition - chapter 18

18 Selenium Selenium (Se), a beneficial element, is one of the most widely distributed elements on Earth, having an average soil abundance of mg kg 1 (1). It is classified as a Group VI A metalloid, having metallic and nonmetallic properties. Selenium was identified in 1818 by the Swedish chemist | 7 14 2006 11 59 AM Page 51 18 Selenium Dean A. Kopsell University of Tennessee Knoxville Tennessee David E. Kopsell University of Wisconsin-Platteville Platteville Wisconsin CONTENTS The Element Selenium Selenium in Phytoremediation .520 Selenium Toxicity to Plants .521 Selenium in the Soil .521 Geological Selenium Availability in Selenium in Human and Animal Dietary Metabolism and Form of Selenium and Human Health .525 Introduction .525 Selenium Deficiency and Toxicity in Anticarcinogenic Effects of Importance of Selenium Methylation in Chemopreventive Activity .526 Selenium Enrichment of Selenium Tissue Analysis Values of Various Plant THE ELEMENT SELENIUM Introduction Selenium Se a beneficial element is one of the most widely distributed elements on Earth having an average soil abundance of mg kg 1 1 . It is classified as a Group VI A metalloid having 515 7 14 2006 11 59 AM Page 51 516 Handbook of Plant Nutrition metallic and nonmetallic properties. Selenium was identified in 1818 by the Swedish chemist Jons Jacob Berzelius as an elemental residue during the oxidation of sulfur dioxide from copper pyrites in the production of sulfuric acid 2 . The name selenium originates through its chemical similarities to tellurium Te discovered 35 years earlier. Tellurium had been named after the Earth tellus in Latin so selenium was named for the moon selene in Greek 3 . Although selenium is not considered as an essential plant micronutrient 4 it is essential for maintaining mammalian .