Description: Oil derived from photosynthetic microalgae is a potential major source of renewable energy, but while industrial-scale efforts to grow algal biomass are underway, it remains an expensive process. The cost of biomass production may be offset by using the algae to simultaneously remediate chemical contaminants from wastewater or natural surface waters. This work examines trace metal accumulation and cycling in algae grown for biofuel use, and evaluates the potential of this approach for remediation purposes. In the system studied, a natural, mixed-species algal community was allowed to develop on a shallow floway fed with water from the York River estuary (VA, USA). Accumulation of metals ranged widely in the algal biomass (Fe 〉 Mn 〉 〉Pb 〉 Cu 〉 V 〉 Cd) and represented removal from the dissolved phase of between 1 and 87% (for Cd and Pb, respectively). These metals were selected for analysis because of their differing geochemical behavior, as well as their importance as micronutrients (Fe, Mn, Cu, V) and toxicants (Pb, Cu, Cd). Most of the algal metal inventory was partitioned in the intracellular fraction (∼30% for Mn, 50–90% for other metals; operationally defined using a chemical wash technique), indicating accumulation due to biochemical demand, not adsorption to cell surfaces. Although algal community composition was similar on the upstream and downstream ends of the floway, the metal inventory was two-fold higher on the downstream end. Differences in metal accumulation may have been related to algal physiology or to pronounced cycles of water pH and dissolved oxygen driven by algal photosynthesis and respiration. Differences in metal removal efficiency and biomass inventory indicate that algal floway systems may be manipulated to optimize remediation of metal-contaminated water.