Heavy Metal and Organochlorine Pollutants in Tissues of Marine Fauna along the Coast of Mombasa Island - Kenya
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Date
2000
Authors
Kipkosgei, Bor Samuel
Journal Title
Journal ISSN
Volume Title
Publisher
Kenyatta University
Abstract
Marine pollution is increasingly becoming a problem along the Kenyan coast.
Heavy metals and organochlorine pollutants have the potential to damage
the delicate marine ecosystem with the result that the country's important
foreign exchange earner - tourism - could seriously be affected. This study
aimed at assessing the levels of cadmium, lead, copper, zinc, manganese,
iron and titanium using Energy Dispersive X-ray Fluorescene (EDXRF) and
Atomic Absorption Spectroscopy (AAS) in selected marine fauna. It further
assessed the levels of lindane, aldrin, dieldrin, endosulfan (o-, B-), DDT
and its metabolites using Gas-Liquid Chromatographic (GLC) techniques.
Certified reference material (Mussel Tissue, MA-M-2ITM, IAEA) was
analyzed by, both AAS and EDXRF techniques, for quality assurance and
control. The two methods are in good agreement and the results are within
10% of the certified values (Appendix III). For statistical analysis,
regression analysis was used to calculate the concentration of samples
and relationship between pollutant concentrations. Some of the
calculations refer to the dry weight of soft tissues. One-way analysis of
variance (ANOVA) was applied with the aid of a computer programme to
investicate the differences in pollutant concentrations between animal
samples and between locations. The level of statistical significance was
set at p::;0.05, unless otherwise stated. Tukey's studentized range test was
used to separete the means when ANOVA indicated significant
differences.
Marine animals used for the study were chosen from molluscs,
echinoderms, crustaceans and chordates sampled mainly along thexiii
coast of Mombasa Island. Some samples were also collected from Vanga
in the South Coast, Nyali Beach and Marine Park in the north.
The four groups of animals were all found to have accumulated heavy
metals and pesticides to some considerable extent. Concentrations of lead
and cadmium ranged from 3.68 - 5.70 ppm and 0.47 - 1.45 ppm
respectively. Pesticide levels were, however, relatively low (0.227 ± 0.026
ppm ). Lindane which was found in 64% of all the animals studied, ranged
from the detection limit (0.01 ppm) - 0.561 ppm.
Marine fauna sampled near the Mombasa showground (English Point)
contained higher than average (4.25±0.37 ppm against a mean value of
2.295±0.22 ppm) levels of the heavy metals studied. Pesticide
concentraion had a similar pattern with a level of 0.383±0.039 ppm against
a mean value of 0.235±0.039 ppm.
Vanga was another place where marine animals were found to have
accumulated the heavy metals and pesticides to a significant (p = 0.0481)
extent (4.07±0.25 ppm and 0.242±0.01 pprn respectively).
The highest concentration of lead (14.80 ± 0.42 ppm ), recorded in this study was found in Crassostrea sp. sampled from Vanga. Cadmium
registered a concentration of 3.49 ± 0.31 ppm in Uca vocans collected
from Mbaraki. The same species registered the highest concentration of
lindane ( 0.561±0.5 ppm ).
Although this study has confirmed that marine fauna from the Kenyan
Coast have accumulated both the heavy metals and pesticides studied, the
levels are generally low compared to the results from a similar study by
Windom (1991). However, unless the pollutants are monitored
continuously, the levels are set to increase, with serious implications.
Description
Masters Thesis
Keywords
Heavy Metal, Organochlorine Pollutants, Marine Fauna, Mombasa Island, Kenya