As shorelines are developed, many wooden structures such as bulkheads and pilings have been placed in marshes and estuaries. Many of these structures have been made of chromated copper arsenate (CCA)-treated wood, which contains high quantities (40 kg/m

) of the toxic metals Cu, Cr and As to prevent rotting and boring by invertebrates. Some quantities of these metals leach out into the ecosystem, especially

when the wood is new. Many studies have focused on leaching and factors that can affect the rate of leaching.