Swirling bubbles of white foam float slowly on the surface of flat water in a Scottish river in a hypnotic, constantly changing pattern of organic shapes

river esk stream dissolved organic carbon ripple fresh water north esk water flowing froth river whitewater swirling turbulent reflection pollution foam foamy surface spume bubbles flow carbon foaming patterns surge spiral float shifting bubble swirl floating contrast calm fishing movement circulate hypnotic detergents change slow drift salmon dark current organic white flat fast eddy