The contents of total copper, total dissolved copper, particulate copper, and free ion copper in the Zhujiang River Estuary were investi-gated in July 2002 and January 2003 respectively, and the spatial distribution trend of these species of copper were compared in twocruises. It was found that, in summer, the total copper content in the Zhujiang River Estuary increased with salinity, while the contentof free ion copper decreased with salinity. However, in winter, the contents of total copper and free ion copper both decreased withsalinity. So, it could be concluded that, copper content and speciation in the Zhujiang River Estuary were regulated by other factorsthan runoff diffusion such as upwelling current. In order to prove the spatial trend of free ion copper content in the Zhujiang River Es-tuary, the cultivation of Dunaliella tertiolecta in waters obtained from sampling stations with different salinities was carried out, andthe copper uptake by algae cells was measured then. It was found that, the cells’ uptake of copper increased with free ion copper, notthe content of total copper. The contents of total copper, total dissolved copper, particulate copper, and free ion copper in the Zhujiang River Estuary were investi-gated in July 2002 and January 2003, and the spatial distribution trend of these species of copper were compared in twocruises. It was found that, in summer, the total copper content in the Zhujiang River Estuary increased with salinity, while the content of free ion copper decreased with salinity. However, in winter, the contents of total copper and free ion copper both decreased with salinity. So, it could be concluded that, copper content and speciation in the Zhujiang River Estuary were regulated by other factors thahan runoff diffusion such as upwelling current. In order to prove the spatial trend of free ion copper content in the Zhujiang River Es-tuary, the cultivation of Dunaliella tertiolecta in waters obtained from sampling stations with different salinities was carried out, and the copper uptake by algae cells was measured then. It w as found that, the cells’ uptake of copper increased with free ion copper, not the content of total copper.