Keberdaan Fosfat Pascaaerasi Hipolimnion pada Lokasi Keramba Jaring Apung di Danau Lido, Bogor, Jawa Barat

Abstract

The purpose of this research is to study about phosphate presence after hypolimnetic aeration in Lido Lake, Bogor, West Java. The research is carried out from May to July 2011 with 5 sampling spot which is decided by purposive sampling based on the aeration equipment outflows, consist of 0 m;1,5 m; 3 m; 4,5 m; and 8 m. Orthophosphate is one of dissolved inorganic phosphate form that can be used by algae and aquatic plant directly. The presence of orthophosphate is affected by dissolved oxygen concentration in water. Orthophospate mostly found in hypolimnetic layer, this is happened because orthophosphate can form a bond and precipitation with Fe, Ca, or Al ion in the oxic condition, then fall to the bottom of water. In the other side, in anoxic condition, the bond between orthophospate and Fe, Ca, or Al ion will be released. This research aim to observe the presence of phosphate after hypolimnetic aeration. This aeration is expected to increase the ability of ions to make a bond and do precipitation with orthophosphate. The research showed that aeration which is done for 10 hours can decrease the orthophosphate concentration in hypolimnetic layer of Lido Lake for 21,05- 97,56%. The most slope is occurred in 3 m distance from the outlet of aeration (97.56%). After the aeration, the decrease of orthophosphate concentration still can be maintained for 5 hours. The concentration of orthophosphate begin to increase after 10 hours from the end of aeration.