The Goudge inquiry report on paediatric pathology has set out important guidance for anyone who gives expert evidence in any Canadian court, and to every lawyer who deals with expert evidence. This absolutely applies to environmental experts. Here is a link to the executive summary- pages 43 to 48 are particularly important, and should be read twice by every expert witness.
Justice Goudge emphasizes the need to formally train experts on how to interact with the justice system. Preparing an expert witness is a checklist you can use to start the process.