Many cite coastal pollution as a likely factor. However, a study published in May in the journal Estuarine, Coastal and Shelf Science concluded that the "green tide" originated from the Jiangsu coast and proliferated in the Yellow Sea before being swept north by the tide towards Qingdao. The study by scientists from the Yantai Institute of Coastal Zone Research under the Chinese Academy of Sciences cited satellite images and field observations to support its claims.