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n, pl -nions or -nia (-nɪə)
(Physical Geography) the upper layer of water in a lake
[C20: from epi- + Greek limnion, diminutive of limnē lake]


(ˌɛp əˈlɪm niˌɒn, -ən)

n., pl. -ni•a (-ni ə)
(in certain lakes) the layer of water above the thermocline.
[1905–10; epi- + Greek límnion small pond]
ep`i•lim•net′ic (-ˈnɛt ɪk) ep`i•lim′ni•al, adj.
References in periodicals archive ?
Fetch determines how deeply wind-driven currents can mix the upper layer of the water column, or epilimnion.
2B), with small fluctuations during most of the year at the epilimnion, except for December 15 th 2010.
En la LR las diferencias entre el epilimnion y el hipolimnion se hicieron cada vez menores hasta la ruptura de la estratificacion termica durante el otono con la mezcla completa de la columna de agua, lo que genero que las condiciones fisicas y quimicas del lago fueran similares a las determinadas en LM y LTP, durante este periodo.
Factors affecting seasonal pattern in epilimnion zooplankton community in one of the largest man-made lake in Africa (Lake Nasser, Egypt).
The high surface temperatures and the presence of a thermocline prevent mixing between the hypolimnion and epilimnion, leading to differences in parameters such as phytoplankton, pH and DO (Gu and Stefan, 1995).
Water samples were taken from the epilimnion and hypolimnion in the deepest portion of the lake using a Kemmerer sampler (Clean Lakes Program 2001; EPA 2007).
2009), the profiles showed homogenous temperature and salinity in the epilimnion, indicative of complete mixing to the halocline.
The results of this study will provide information on the physico--chemical parameters of the lake at the epilimnion.