Zoeken
Zoeken kan via de modus 'eenvoudig zoeken' (één veld) of uitgebreid via 'geavanceerd zoeken' (meerdere velden). Zo kan je bv. zoeken op een combinatie van een auteursnaam (auteur), een jaartal (jaar) en een documenttype.
Boekenmand
Nuttige resultaten kan je aanvinken en toevoegen aan een mandje. De inhoud hiervan kan je exporteren of afdrukken (naar bv. PDF).
RSS
Op de hoogte blijven van nieuw toegevoegde publicaties binnen uw interessegebied? Dit kan door een RSS-feed (?) te maken van jouw zoekopdracht.
nieuwe zoekopdracht
Assessment of environmental quality using diatoms in Nairobi River, Kenya
Ndiritu, G.G. (2001). Assessment of environmental quality using diatoms in Nairobi River, Kenya. MSc Thesis. VUB: Brussel. 100 pp.
|
| Beschikbaar in | Auteur |
|
Documenttype: Doctoraat/Thesis/Eindwerk
|
| Abstract |
Environmental variables and diatom data were collected from Nairobi River, Kenya to study the response of diatom assemblages on natural and artificial substrates to water pollution. Fifteen stations were sampled, covering a distance of 60 km from the source. The river was experiencing agricultural, domestic and industrial pollution. Environmental variables data were described by quartiles and standard error; explored using PCA and cluster analysis; and analysed using spearman correlation, ANOVA and multiple regression. Species data was analysed using, biodiversity indices (Pielou 1975, Hill 1973). Multivariate analyses used included the two way indicator species analysis (TWINSPAN) and cluster analysis for classification; and canonical correspondence analysis (CCA) and detrended correspondence analysis (DCA) for ordination. Ecological indicator values were also used (van Dam 1994). The multivariate analysis revealed three types of gradients in both substrates. The first gradient represented the upstream stations, which corresponded to high oxygen. The second gradient related to high agricultural pollution and had high NO3. The third group corresponded to both industrial and domestic pollution and included stations situated in lower parts of the river. Those stations had high measurernents of total dissolved solids, total suspended solids and PO4. Species richness, diversity and evenness tended to be higher in the second group while high densities were recorded in the third group. Our results showed that the response of diatom assemblages to environmental change and substrate type was observed in species composition variation. Multivariate analyses and ecological indicator values revealed this response and were preferred to species diversity measures. |
IMIS is ontwikkeld en wordt gehost door het VLIZ.
