Summary
Two experiments were carried out to determine the rate of release of ions to lake water from dry grass (largely Eragrostis species) and dung from elephant, impala and buffalo. The ions released most rapidly were PO3 3- and K+, followed by NO3 - and Ca2+ + Mg2+; the smallest increase was shown by Na+. In general, dung derived from grass released ions more rapidly than grass itself; the results are discussed in relation to ash analyses of grass and dung. The possible importance to Lake Kariba of the nutrients released by grass and dung following immersion under natural conditions is considered.
Résumé
On a procédé à la réalisation de deux expériences visant à déterminer la vitesse de libération des ions dans l'eau d'un lac à partir d'herbe sèche (appartenant principalement à l'espèce Eragrostis) et de crottin d'éléphant, d'impala et de buflle. Par ordre décroissant, on mesure les vitesses de libération des ions les plus grands pour PO4 3- et K+, et ensuite pour NO3 - et Ca2+ + Mg2+; Na+ manifeste l'augmentation de concentration la plus faible. En règle générale, le crottin formé à partir d'herbe a libéré les ions à vitesse plus grande que l'herbe elle-même; les résultats sont interprétés par rapport à des analyses de cendre d'herbe et de crottin. On a cherché à estimer l'importance que peuvent présenter, pour le lac Kariba, la libération de ces éléments nutritifs après immersion dans des conditions naturelles.
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Present address: Biology Department, Chancellor College, University of Malawi, Limbe, MalawiN
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McLachlan, S.M. The rate of nutrient release from grass and dung following immersion in lake water. Hydrobiologia 37, 521–530 (1971). https://doi.org/10.1007/BF00018817
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DOI: https://doi.org/10.1007/BF00018817