Fig. 1. Location of the study site: (i) Sweden, located in the Baltic Sea; (ii) the Swedish Northern Baltic Sea River Basin District, including Lake Mälaren (1); and (iii) the Himmerfjärden study site area; divided in the model areas “Hallsfjärden” (2), “Näslandsfjärden” (3), and "Himmerfjärden proper" (4). Via "Svärdsfjärden” (5) the study site area is connected to the open Baltic Sea (6). The red circle in "Himmerfjärden proper" is the discharge point of the Himmerfjärden sewage treatment plant. The colors in the study site map indicate: blue = water (dark is deeper for marine areas), green = forest, yellow = arable land, orange = urban area. ©Lantmäteriet, permission I 2011/0094


Fig. 1