Urban dietary heavy metal intake from protein foods and vegetables in Dar es salaam
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Date
2011
Journal Title
Journal ISSN
Volume Title
Publisher
International Journal of Biological and chemical science
Abstract
This was an investigation to characterize seasonal and spatial distribution of particulate organic matter
(POM) in the surface water of Lake Victoria at Speke Gulf, by using carbon-13 and nitrogen-15 isotopic
signatures. Speke Gulf is under the influence of terrestrial inflow through river Simiyu. The POM from the lake
surface water had higher C:N ratio values decreasing towards the deeper lake water, an indication of decreasing
nitrogen content relative to carbonic materials. Samples away from the river mouth provided C:N ratios within
the Redfield ratio range (C:N:P; 106:16:1) indicating materials of phytoplanktonic origin. The POM isotopes
composition indicated a maximum δ 13 C value of −21.2‰ close to the river mouth and lowest value (~ −25‰)
away from the river influence. The δ 15 N maximum (14.7‰) was observed near the river mouth with lower
values (5.8‰) found in deeper waters away from the river mouth. Overall, there was a general decrease of 13 C
and δ 15 N values from shallow water to deeper water. There was higher δ 15 N value dispersion (std. Dev. ±3.4‰)
compared to δ 13 C values with std. Dev.±1.2‰. These values also varied with seasons, a phenomenon showing
significant influence of land run off on the lake elemental distribution, carbon and nitrogen in particular.
Description
Journal Article
Keywords
Lake Victoria, Particulate Organic Matter, Carbon and nitrogen, Isotope signatures