tailieunhanh - Applications of Environmental Aquatic Chemistry: A Practical Guide - Chapter 4

TRONG BỐI CẢNH kim loại 4,1 NƯỚC Một cái nhìn bình thường ở bảng tuần hoàn cho thấy đó NHẤT trong những yếu tố (khoảng threefourths) là kim loại hoặc kim .* Nó thường xảy ra trong văn học ít hoặc không có môi trường đó phân biệt được giữa IS kim loại và kim, đặc biệt là kim Đối với thạch tín, selenium, và antimon. Để thảo luận hành vi của họ hóa chất, các nguyên tố kim loại Chia vào tháng Ba Be các lớp học nói chung: 1. Kim loại kiềm: Li, Na, K, Rb, Cs, và. | 4 Behavior of Metal Species in the Natural Environment METALS IN WATER Background A casual glance at the periodic table shows that most of the elements about three-fourths are metals or metalloids. It often happens in environmental literature that little or no distinction is made between metals and metalloids especially for the metalloids arsenic selenium and antimony. To discuss their chemical behavior the elemental metals may be divided into three general classes 1. Alkali metals Li Na K Rb Cs and Fr periodic table group 1A . 2. Alkaline metals Be Mg Ca Sr Ba and Ra periodic table group 2A . 3. Metals not in the alkali or alkaline groups include the transition metals all the group B periodic table metals the metals and metalloids in groups 3A through 6A and metals whose classifications are not based primarily on periodic table groups the so-called trace or heavy Heavy metals in surface waters can be from natural or anthropogenic sources. Currently anthropogenic inputs of metals exceed natural inputs. Living organisms require trace amounts of some heavy metals including cobalt copper iron manganese molybdenum vanadium strontium and zinc. Excessive levels of essential metals however can be detrimental to the organism. Nonessential heavy metals of Metalloids are those elements in periodic table groups 3A through 6A that have electrical and chemical properties intermediate between those of metals and nonmetals. They are B Si Ge As Sb Te and Po. For regulatory purposes it is sometimes useful to group metals and metalloids together as when they share the same analytical method . ICP ion-coupled plasma spectroscopy . y The term heavy metals is often encountered in texts and reports usually meaning metals with atomic numbers equal to or greater than Cu at. no. 29 especially metals exhibiting toxicity. However the term heavy metals has no precise definition and its use is inconsistent Duffus 2002 . Another designation often used is trace metals .