The use of water hyacinth (Eichornia Crassipes Mart. (SOLM) a biological indicator of chromium levels in Laguna de Bay

Date

1989

Abstract

A study was conducted on the potential application of water hyacinth as biological indicator in the monitoring of chromium levels in Laguna de Bay. Water hyacinth samples were taken from 17 stations along the lake and the mouth of major tributaries in three sampling occasions from May 1987 to February 1988. Chromium concentrations in the stems and leaves of water hyacinth varied from 673 to 3350 ppb in dried samples and 114 to 467 ppb as estimated for the wet weight of the plant. Aqueous concentrations during the time of sampling ranged from 1-13 ppb. Seasonal variations in aqueous and plant tissue concentrations of chromium was significant but spatial differences were slight. The accumulation potential of water hyacinth expressed as enrichment factors or ratio between plant and aqueous concentrations varied from 118 to 848 for oven dried plants and from 20 to 144 for fresh plants. The observed enrichment factors were sufficiently high to raise chromium concentrations to levels detectable by common atomic absorption spectrophotometry. Plant tissue concentrations however were slightly correlated with aqueous concentrations for both arithmetic (r = 0.59737, P .05) and logaritmic values (r Using estimates of the natural variability, measurement errors, and data collection costs, alternative sampling designs for monitoring of chromium using water and water hyacinth as indicators were examined. The sampling design of existing water quality monitoring programs in Laguna de Bay were found to be applicable for trend monitoring of chromium levels. Optimization suggests that monitoring of chromium levels in Laguna de Bay using water hyacinth may be equally cost effective. Plant tissue concentrations of chromium may be used as surrogate variables for aqueous values once a predictive relationship between the two variables is established. However, given the

33 problems associated with the applications of water hyacinth as indicator, direct analyses of water is considered more reliable if a more practical and sensitive method for chemical analyses of heavy metals at trace quantities is employed.

Document Type

Master Thesis

Degree

Master of Science in Environmental Science

College

School of Environmental Science and Management (SESAM)

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