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Water quality trends and trophic state
assessment of Laguna de Bay, Philippines
Carlito R. Barril*, Elvira T. Tumlos
Institute of Chemistry C. A. S., University
of the Philippines Los Ratios College, Laguna, 4031 Philippines
*Corresponding author Fax: (6349,1-536-0649; E-mail: memsi@haylinkmozcom.com
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Abstract
Monitoring of key water quality parameters
in Laguna de Bay was carried out from 1986 to 1996 to determine
trends in water quality and the trophic state of the lake. Monthly
sampling and field analyses were made at randomly selected sites
of the la/ca Three-year trend analysis of the annual mean values
of some key water quality parameters showed the worsening condition
of the lake. Ammonia-nitrogen, nitrate-nitrogen, ortho-phosphate,
total phosphorus, chemical oxygen demand, turbidity conductivity
and chlorides increased while alkalinity clarity and dissolved oxygen
decreased. The lake is judged to be extremely trophic or dystrophic.
Uses of the lake as a fishery resource and as a source of domestic
water supply are briefly discussed.
Keywords: eutrophication, hypertrophic, dystrophic
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