PhD Theses

Permanent URI for this collection

http://192.168.13.253:4000/handle/123456789/1251

Browse

Browsing PhD Theses by Author "Andrew, Minu"

Now showing 1 - 1 of 1
  • No Thumbnail Available
    Item
    Investigation of anthropogenic and climatic influences on nutrients and organic matter dynamics in the Rufiji delta mangroves, Tanzania.
    (University of Dar es Salaam, 2018) Andrew, Minu
    Anthropogenic and climatic influences within and/or around the Rufiji Delta mangroves has increased considerably. These influences affect availability of nutrients and organic matter which in turn pose a threat to the mangrove ecosystems. The study therefore was designed to examine anthropogenic perturbation on nutrients and organic matter dynamics in the Rufiji Delta mangroves. Also, the future net primary productivity of the Rufiji Delta in relation to changes in temperature was modeled. Sediment cores were collected from six sampling locations in the Rufiji delta mangrove forests. The geochronology was derived based on the distribution of 210Pbex methodology. The trace metals in sediments was sequentially extracted using the BCR sequential extraction scheme and analyzed using an ICP-MS. Future primary productivity was studied by developing a simulation model using a dynamic software program called STELLA 8.1.1 version. The results showed that the mass accumulation rates ranged from 0.4 g cm-2 yr-1 (cores NR3 and NR4) to 1.75 g cm-2 yr-1 (core SR1). Trace metals in the cores were mainly associated with the residual phase implying that trace metals are mainly of crustal origin and they are least available for plant uptake. The C: N ratios have indicated that the mangrove derived and terrestrial derived organic sources contribute substantially to the sedimentary organic matter pool. Similarly, n-alkanes and fatty acid has indicated both aquatic microbial and terrestrial sources were derived from vascular plants. Net primary productivity has indicated an increase with time. Similarly, a cycle of an abrupt increase in net primary productivity was noted. This result implied that the Rufiji Delta mangrove forest will periodically interchange its role as being the nutrient sink as well as source.