Fate and effects of microcystin in nearshore and upland environments : a literature review

Abstract

Dredged material (DM) impacted by harmful algal blooms (HABs) potentially introduces algal toxins (e.g., microcystins (MCs)) to areas where material is being stored (e.g., confined disposal facilities (CDFs)) or beneficially used for nearshore and upland placement for land and habitat improvements. The objective of this study was to conduct a literature review of the current information related to the fate and transport of MCs in upland environments. The study also focused on detailing relevant pathways for potential human exposures during, and following, relocation of DM from collection to placement sites for beneficial use. BACKGROUND: To appropriately manage the 200-300 million cubic yards (CY) of DM collected annually in the United States (U.S.), beneficial use programs are increasingly being favored over traditional disposal practices due to the economic, social, and ecological benefits, along with the limited capacity of CDFs. However, potential risks associated with DM re-use must be evaluated prior to placement. Recently, the potential occurrence of MCs in DM sourced from HAB-impacted water bodies has raised concerns regarding the risks with upland and nearshore placement of DM. MCs are known hepatotoxins that can pose ecological and human health risks. The presence and persistence of MCs in DM have the potential to prevent the beneficial use of otherwise suitable material sourced from HAB-impacted water bodies. APPROACH: A literature review was conducted to document what is currently known about the fate and transport of MCs in DM relocated to upland environments for beneficial use, with specific emphasis on relevant exposure pathways to human receptors. The review will also document gaps of information related to the fate of MCs in upland environments and inform future research needs. This documentation provides available information that can be used to inform the assessment and management of risks associated with MCs in upland environments. RESULTS: Chemical and physical properties of MCs. MCs are common cyanotoxins found in waters through the world (Carmichael 1992), and are relatively stable in the aquatic environment due to their resistance to hydrolysis at near neutral pH (USEPA 2015a). Numerous genera of cyanobacteria are associated with MC production and are known to bloom to high densities, including Microcystis,