areas, and the possible permanent loss of it in hypoliranetic depths. 

 Although insoluble phosphorus accumulates mainly at the bottom, this is 

 also the region of greatest phosphorus solubility (Neess, 19h9) . Soluble 

 phosphorus is highly motile, enabling it to form insoluble compounds with 

 calcium and iron (Lawson, 1937; Ifiesner, 1937 j Hasler and Einsele, I9U8; 

 Neess, 19^9) . 



A study by Barrett (1953) indicates that the rate of disappearance 

 for added phosphorus from epilimnial water was related to alkalinity 

 (theoretical lower limit of alkalitrophy seemed to be between 120 and I60 

 parts per million K.O.k.), and also that the amount of exchangeable phos- 

 phate in bottom sediments was inverselj'" related to the ratio of marl to 

 organic matter. Added phosphorus accumulated in the hypolimmon or sediments 

 in the following situations; In lakes where sediments were high in organic 

 matter and low in marl, phosphorus was adsorbed by sediments and remained 

 in an exchangeable form; where sediments were high in both marl and organic 

 matter, phosphorus accvimulated in hypolimnetic water and sediments; where 

 sediments were very low in organic matter and verj'- high in marl, phosphorus 

 did not accumulate in hypolimnetic water nor was it adsorbed by sediments^ 

 but probably became fixed in insoluble precipitates. 



Recent experiments with radioactive phosphorus (P32) in stratified 

 lakes have furthered the understanding of phosohorus metabolism and per- 

 haps the action of other elements. McCarter et al. {19^2) traced the 

 movements of P32 in a lake after introducing it below the thermocline. 

 Lateral r.iovement, quite pronounced in the iirection of the outlet, 

 averaged 3 meters per day. Vertical movement was slight and penetration 

 of soluble phosphorus above the thermocline was not evidenced. Hutchinson 

 and Bowen (19^0) expressed the opinion that most of the added phosphorus 

 enters phytoplankton. The leaves and stems of some aquatic plants absorb 

 p32 before it enters the root system, according to Hayes et al. (1952). 

 Coffin et al. (I9h9) studied living organisms more closely to find absorp- 

 tion of p32occurring in a matter of minutes and hours. Plants and micro- 

 or^.anisms absorbed phosphorus directly. Zooplankton obtained it either 

 directly, or indirectly by feeding on smaller organisms. Fish apparently 

 acquired P32 by feeding upon plankton and similar organisms. Recent experi- 

 ments have indicated that fish may absorb phosphorus and other nutrient 

 substances directly from water. These authors further found that zoo- 

 plankton could concentrate phosphorus up to IiO,000 times the level present 

 in surrounding water. An average of concentration ratios, given for 

 several aquatic plants and animals, showed that the floral level of phos- 

 phorus was about 2^0, and the f aunal level about 20,000 times the water 

 content. 



Hutchinson and Bowen (1950) postulated a steady exchange between 

 organic and phosphate phosphorus, and described rapid gains of P-' by 

 the h-j/polinTiion in terms of seston sedimentation. They concluded that 

 T^'- replacement in the epilimnion occurred each 3 weeks. Hayes et al. 

 (1952) proposed quantitative exchanges of phosphorus between the soluble 



