Cycles and spirals of nutrients
https://stroudcenter.org/wp-content/uploads/publication-e1554320152730.jpg 350 210 Stroud Water Research Center Stroud Water Research Center https://stroudcenter.org/wp-content/uploads/publication-e1554320152730.jpgNewbold, J.D. 1992. Pages 379–408 in P. Calow and G.E. Petts (editors). The rivers handbook, volume 1: hydrological and ecological principles. Blackwell Scientific, Oxford, England.