Modeling runoff-sediment influx responses to alternative BMP interventions in the Gojeb watershed,Ethiopia, using the SWAT hydrological model

Environmental Science and Pollution Research - The Soil & Water Assessment Tool (SWAT) has been calibrated over a 33-year period to evaluate the Gojeb watershed’s hydrological...     

Etude des activites phosphatasiques du sol: Effets du pH et de certains herbicides

Phosphatasic activities in four alkaline soils and two acidic ones were studied. In all cases, the values for soil pH determined the prominent phosphatasic activity. The results indicated that acidic phosphatase was prominent in acidic soils, alkaline phosphatase was prominent in alkaline ones.We studied the action of 16 herbicides in two soils, an alkaline one and an acid one. We did not find any significant effect on the phosphatasic activities.     

Levels of polychlorinated biphenyls in Patella piperata from the coast of Fuerteventura (Canary Islands, Spain)

Concentration of 51 PCB congeners were determined in the visceral mass of the endemic limpet Patella piperata, sampled in four stations in the coast of Fuerteventura (Canary Islands, Spain) during 1991-1995, and evaluated in order to assess the origin of their contamination and the possibility of this limpet being used as a bioindicator organism for PCB contamination. PCB extracted from samples were fractionated on Florisil columns and analysed by capillary gas chromatography with flame ionisation detector. Principal Component, Factor and Cluster Analysis were used to study the patterns and relationships among PCBs.     

Land use and land cover dynamics in the Keleta watershed,Awash River basin,Ethiopia

Unprecedented pace and magnitude of land use/land cover (LULC) change in the Ethiopian highlands is a key problem threatening the natural ecosystem and creates vulnerability to an environmental hazard. A combination of remote sensing, field observations and focus group discussions were used to analyze the dynamics and drivers of LULC change from 1985 to 2011 in the Keleta watershed, Ethiopia. Supervised image classification was used to map LULC classes. Focus group discussions and ranking were used to explain the drivers and causes linked to the changes. The result showed rapid expansion of farmland and settlement (36%), shrublands cover shrinking by 50%, while the size of degraded land increased by 45%. Rapid population growth, rainfall variability and soil fertility decline, lack of fuelwood and shortage of cultivation land were ranked as the main causes of LULC change in the watershed according to the focus group discussion. Further effort is needed to improve the creation of new job opportunity, promotion of improved technologies to boost productivity and soil fertility, provide credit facility, extra push on irrigation infrastructure development and soil, water and natural ecosystem conservation practices. Generally, better community-based land resource management will need to ensure sustainable rural livelihoods.     

Intra-specific variability in the response of maize to arsenic exposure

The response of maize (Zea mays L.) to inorganic arsenic exposure was studied, at the seedling stage under hydroponic conditions, preliminarily in sixteen lines (fourteen hybrids and two inbred lines) and then, more deeply, in six of these lines, selected by showing contrasting differences in their sensitivity to the metalloid. The results indicated that (i) maize is rather tolerant to arsenic toxicity, (ii) arsenite is more phytotoxic than arsenate, (iii) roots are less sensitive than shoots to the metalloid, (iv) a great accumulation of non-protein thiols (probably phytochelatins), without substantial effect on the glutathione content, is produced in roots but not in shoots of arsenic-exposed plants and (v) maize is able to accumulate high levels of arsenic in roots with very low translocation to shoots. The study, thus, suggests that maize, for its very low rate of acropetal transport of arsenic from roots to shoots, may be a safe crop in relation to the risk of entry of metalloid in the food chain and, for being an important bioenergy crop capable of expressing high levels of arsenic tolerance and accumulation in roots, may represent an interesting opportunity for the exploitation of agricultural useless arsenic contaminated lands.