On Manganese in Sea and Fresh Waters

Abstract

A method of estimating the maximum quantity of manganese available to plants in sea and fresh waters is described.Samples of sea water collected off Plymouth in 1948 contained 0·7–1·0 mg. Mn/m.³in solution plus any particles soluble at pH 4·6. After storage and sedimentation of particulate matter, the quantity decreased to 0·0–0·25 mg./m.³Samples collected off the Isle of Man, an area with a rich summer population of flagellates, contained 2·0–2·6 mg./m.3The river Yealm, south Devon, on leaving Dartmoor contained 1 mg., and after passing through agricultural land 10 mg.\m.³Lakes and streams in the English Lake District contained 6–40 mg.\m.³The least fertile waters contained the least soluble manganese.