Comparison of copper speciation in the Zhujiang River Estuary between summer and winter:implication for upwelling current

The contents of total copper,total dissolved copper,particulate copper,and free ion copper in the Zhujiang River Estuary were investigated in July 2002 and January 2003 respectively,and the spatial distribution trend of these species of copper were compared in two cruises.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 than runoffdiffusion such as upwelling current.In order to prove the spatial trend of free ion copper content in the Zhujiang River Estuary,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 was found that,the cells' uptake of copper increased with free ion copper,not the content of total copper.