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Flo là nguyên tố nhẹ nhất trong Tập đoàn VII của bảng tuần hoàn, với sự nguyên tử số 9 và trọng lượng nguyên tử của 18,998. Nó có một đồng vị duy nhất, và hóa trị của nó trong tất cả các hợp chất tự nhiên là một. Mặc dù có chứa chất florua (F) không được liệt kê là một trong những tiêu chí "chất gây ô nhiễm" quy định của Mỹ Cơ quan Bảo vệ môi trường, nó vẫn là một khí rất quan trọng không khí gây ô nhiễm. Thật vậy, F là các chất gây ô nhiễm không khí phytotoxic. | Chapter 10 Environmental Fluoride 10.1 INTRODUCTION Fluorine is the lightest element in Group VII of the periodic table with the atomic number 9 and the atomic weight of 18.998. It has a single isotope and its valence in all naturally occurring compounds is one. Although fluoride F is not listed as one of the Criteria Air Pollutants regulated by U.S. Environmental Protection Agency it is nevertheless a very important gaseous air pollutant. Indeed F is the most phytotoxic air pollutant because it can damage plants at extremely low concentrations. Additionally adverse effects are not limited to those caused by airborne F high levels of waterborne F are also hazardous to both human and animal health. For example in China and India millions of people are suffering from dental and skeletal fluorosis -abnormal or poisoned tooth and bone conditions induced by F - mainly due to consumption of high levels of F in drinking water. This chapter begins with an introduction to the sources and forms of F found in the environment and then discusses the way in which F influences the health of plants animals and humans. Whenever applicable reference will be made to the growing concerns shared by several less-developed countries that are experiencing significant growth in their economies such as China and India. 10.2 OCCURRENCE AND FORMS OF FLUORIDE 10.2.1 Introduction Fluoride is ubiquitous it rarely occurs free in nature but combines with a variety of elements to form fluorides that exist in minute amounts in air water minerals and soils foods and body tissues. Fluoride found in the environment is derived from both natural and anthropogenic sources. Natural sources of F include volcanism aerosols from ocean spray and soil particles blown into the atmosphere etc. while anthropogenic sources are found mostly in industrial facilities. Fluoride emitted into the atmosphere from these sources consists of both gaseous and particulate forms and as such can contribute F to surface waters. .
