Evaluate the collective function of references cited together in a given text segment.
Classify their combined role into one of the following categories: 'method', 'background', or 'result'.

Text:Once in aquatic environments, inorganic Hg is microbiologically transformed to MeHg (Anderson et al. 2004; Zahir et al. 2005), making it more prone to biomagnification (Zahir et al. 2005).
Category: