This chapter reviews the current state of knowledge on the speciation of arsenic in aquatic and terrestrial environments. Due to the enormous differences in the toxicity of different arsenic species, knowledge of arsenic speciation is of utmost importance in terms of environmental management and remediation. The effects of natural organic matter, pH, Eh, adsorption, desorption, biological transformations and key inorganic interactions are considered. 2013 by Nova Science Publishers, Inc. All rights reserved.
