对于河口湾(estuary),许多欧美学者有过各种类似的定义,其中较全面的有两家: Pritchard提出:“河口湾是一个半封闭的海岸水体,它与外海有自由的联系,在此水体内的海水受到来自陆地径流某种程度的冲淡。”他对其定义还作了如下进一步的说明: 首先,“河口湾是一个半封闭的海岸水体”。这意味着河口湾的重要特性是其间的水运动受到它的海岸边界的明显制约。据此,像波罗的海、波的尼亚湾和芬兰湾等较大的水体, For the estuary, many European and American scholars have come across a variety of similar definitions, two of which are more comprehensive: Pritchard states: “The estuary is a semi-enclosed coastal body that has free connections with the open sea The seawater in the body of water is somewhat diluted by runoff from the land. ”He further clarified his definition as follows: First,“ the estuary is a semi-enclosed coastal body of water. ” This means that an important characteristic of estuaries is that the water movement during this period is clearly restricted by its coastal borders. Accordingly, larger bodies of water such as the Baltic Sea, the Gulf of Bothnia and the Gulf of Finland,