Environmental and Socio-Economic Impacts of Kariba Weed Infestation of Lakes Kyoga and Kwania, Uganda

The objective of this study was to quantify the coverage of Kariba weed (Salvinia molesta) on lakes Kyoga and Kwania and document the environmental and socio-economic impacts associated with its infestation. Data on weed infestation status was collected in 2017 and compared with pre-infestation period of 2013. Weed infestations were approximately 15,643 and 13,688 ha on lakes Kyoga and Kwania respectively. The infestation impaired fishing activities, water quality, water abstraction and water transport. They also led to 20.4, 60.1, 7.7, 17.6 and 5.7 kg reduction in catches per day for Tilapia, Mukene, Catfish, Nile perch and Mudfish respectively. The infestations were also associated with a general increase in the prices of the fish. Individual fishermen registered losses in fish revenue. Household spent approximately UGX 108,523 annually as treatment costs for diseases associated with weed infestation. While 32% of the respondents tried to manually control the waterweed at approximately UGX 83,988/year, the mobile nature of the weed rendered these efforts unsuccessful. A strategy to sustainably control the waterweed using specific bio-control agents (Cyrtobagous salviniae) is recommended.

Adsorption of chromium (Cr6+) on dead biomass of Salvinia molesta (Kariba weed) and Typha latifolia (broadleaf cattail): isotherm, kinetic, and thermodynamic study

This study evaluated the adsorption of Cr6+ from aqueous solution using dead biomass of aquatic plants Salvinia molesta (Kariba weed) and Typha latifolia (broadleaf cattail). The batch experiments were carried out to study the effects of pH, adsorbent dose, initial metal concentration, contact time, agitation speed in rotation per minute (rpm), and temperature. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were used to characterize the adsorbent and analyze the functional groups and morphology of the adsorbent, respectively. The hydroxyl and amine groups were the main functional groups involved in the adsorption. Both adsorbents showed good results at pH 1, metal concentration of 20 mg/L for Cr6+ removal, and adsorption equilibrium was attained within 60 min with 150 rpm at 25 °C. The adsorption rate obtained was above 95% for both the adsorbents at a dose of 0.150 g for S. molesta and 0.8 g for T. latifolia. Isotherm and kinetic models were applied on the adsorption data. The monolayer adsorption capacity (qm) was found to be 33.33 mg/g for S. molesta and 10.30 mg/g for T. latifolia. The Langmuir isotherm was better fitted to S. molesta, while the Freundlich isotherm was better fitted to T. latifolia. It was reported that the pseudo-second-order model (R2 = 0.999) was better fitted to the adsorption data for both the adsorbents. The thermodynamic study was also conducted and found the adsorption process was exothermic and spontaneous. Results revealed the good adsorption potential of S. molesta and T. latifolia, and they can be used for the removal of hexavalent chromium.

Salvinia molesta (kariba weed).

S. molesta is a free-floating aquatic plant native to south-eastern Brazil. It has been spread widely throughout the world during the past 50 years and is invasive in a variety of aquatic habitats, including lakes, rivers and rice paddies. Based on the environmental, economic and human health impacts, S. molesta ranks a close second behind water hyacinth on a list of the world's most noxious aquatic weeds. It has also been recently added onto the list of the world's 100 most invasive species.

Effect of Combination Kiambang (Salvinia molesta) and Zeolite on Consentration of Heavy Metal Cadmium (Cd).

Water is the most important requirement for all organisms, either to humans, plants, animals, and microorganisms. It was caused water function in the growth and survival organisms. Aquaculture is an activity to maintain, raise, and/or breeding fish and harvest their products in a controlled environment. Cultivation was done in a sustainable manner for the benefit.Pollution in water can be caused death of fish is heavy metal cadmium (Cd) pollution. Processing of heavy metal contaminated water is the most simple and low cost is a biological treatment with kariba weed (Salvinia molesta). But the effect of kariba weed to the decline of heavy metal cadmium is not significantly reduced, so that needs to be combined with the zeolite so that the heavy metal cadmium decline more significantly. This reseacrh to determine the effect of the combination kariba weed (Salvinia molesta) and zeolite to the decline of the heavy metal cadmium (Cd). This reseacrh uses a completely randomized design (CRD) with four treatments performed five repetitions, treatment A using 0 g kariba weed and 150 g of zeolite, Treatment B using 50 g kariba weed and 100 g of zeolite, Treatment C using 100 g kariba weed and 50 g of zeolite and treatment D using 150 g kariba weed and 0 g zeolite. The result on this research analize by ANOVA statistical test (Analisis of Variance) to know there was the different between treatments, afterwards, continued by space doubled test Duncan. The result showed combination kariba weed (Salvinia molesta) and zeolite significant effect on decreasing the concentration of heavy metal cadmium (Cd) (F count > F Tabel 0.05). It is evident in this research, and only had one week treated water cadmium (Cd) of 1 ppm concentrations is fall. The averages treatment on decreasing concentration heavy metal cadmium (Cd) was treatment A 98,7%, tretment B 97,1%, treatment C 97,2 % and treatment D 95,8%.