The final publication is available at Springer via http://dx.doi.org/10.1007/978-1-4614-1463-6_1 ; Arsenic (As) is an element belonging to the group V-A, and it demonstrates characteristics of a metalloid. Because arsenic more easily forms anions, its non-metal properties dominate. When arsenic is in an oxidation state of +5, it acts similar to phosphorus, a fact that has many implications for the way in which it reacts in soil, as well as its potential toxicity in plants. The most common oxidation states of As are -3, 0, +3, and +5. Arsines and metal arsines are those in which As has an oxidation state of -3, and these forms are very unstable under oxidizing conditions. Under aerobic conditions, the oxidation state of As tends to be +5, and when this occurs at a pH between 2 and 3, arsenic acid (H3AsO4) is formed. When the pH rises to values between 3 and 11, this compound disassociates to H2AsO4 - and HAsO4 2- (Smedley and Kinninburgh 2002). Under anaerobic conditions, the predominant As species is H3AsO3