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African tropical montane forests are facing fast and dynamic changes in land use. However, the impacts of these changes on stream water quality are understudied. This paper aims at assessing the effect of land use and physical catchment characteristics on stream water concentrations of dissolved organic carbon (DOC), total dissolved nitrogen (TDN), nitrate (NO 3 -N) and dissolved organic nitrogen (DON) in the Mau Forest, the largest tropical montane forest in Kenya. We conducted five synoptic stream water sampling campaigns at the outlets of 13–16 catchments dominated by either natural forest, smallholder agriculture or commercial tea and tree plantations. Our data show a strong effect of land use on TDN and NO 3 -N, with highest concentrations in stream water of catchments dominated by tea plantations (1.80 ± 0.50 and 1.62 ± 0.60 mg N l −1 , respectively), and lowest values in forested catchments (0.55 ± 0.15 and 0.30 ± 0.08 mg N l −1 , respectively). NO 3 -N concentration increased with stream temperature and specific discharge, but decreased with increasing catchment area. DOC concentrations increased with catchment area and precipitation and decreased with specific discharge, drainage density and topographic wetness index. Precipitation and specific discharge were also strong predictors for DON concentrations, with an additional small positive effect of tree cover. In summary, land use affects TDN and NO 3 -N concentrations in stream water in the Mau Forest region in Kenya, while DOC and DON were more related to hydrologic regimes and catchment properties. The importance of land use for NO 3 -N and TDN concentrations emphasizes the risk of increased nitrogen export along hydrological pathways caused by intensified land use and conversion of land to agricultural uses, which might result in deterioration of drinking water quality and eutrophication in surface water in tropical Africa. [ABSTRACT FROM AUTHOR]

Since 1990 carbon dioxide emissions in Africa have increased by about 50%. The total carbon dioxide emissions of the entire African continent are not, however, anywhere near those of countries such as India or China. Yet certain African countries have per capita emissions comparable to some European countries. What is the outlook for Africa? How should African countries respond as it becomes increasingly likely that climate change is occurring? Increased industrial growth and more foreign investment in Africa, especially in countries that are politically and economically stable, have led to huge commercial developments such as the In Salah gas project in Algeria, which releases more than a million tons of carbon dioxide annually; and synthetic fuel plants and power stations in South Africa that generate more than 350 million tons per year. In this perspective should some African countries be required to limit greenhouse gas emissions or should they be immune to 'environmental taxation'? This paper critically reviews the carbon dioxide problem in some parts of Africa and its role in climate change. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, energy consumption and carbon dioxide emissions from 17 countries of the Middle East and North Africa are studied using Data Envelopment Analysis. Four indicators for the year 1996 are employed in the analysis. The analysis shows that Sudan, Bahrain and Oman are considered efficient, and Saudi Arabia is rated as the least efficient under constant returns to scale (CRS) assumption. Mauritania and Israel are considered efficient under variable returns to scale (VRS) assumption, indicating that the CRS inefficiency of these two countries is due to the fact that they are not operating at the best possible scale size. The patterns of changes in efficiency of the countries are further analyzed using Malmquist Productivity Index (MPI) approach for the period of 1992–1996. The analysis shows that there is progress in achieving higher values of output-side indicators and in achieving lower values of the input-side indicators in the year 1996 compared to 1992 for 5 out of the 17 countries (Algeria, Egypt, Sudan, Oman and Syria). [Copyright &y& Elsevier]

The characteristics of colored dissolved organic matter (CDOM) as well as the concentrations and stable isotope composition (δC) of dissolved organic carbon (DOC) were characterized in several large rivers of Africa including the Congo, Niger, Zambezi, and Ogooué basins. We compared the spatial and temporal patterns of dissolved organic matter (DOM) quantity and quality along with various environmental gradients, including hydrology, river size, catchment vegetation, and connectivity to land. The optical proxies used include the absorption coefficient at 350 nm, the specific ultra-violet absorbance, and the spectral slope ratio ( S = 275-295-nm slope divided by 350-400-nm slope). Our results show that land cover plays a primary role in controlling both DOC concentration and optical properties of DOM in tropical freshwaters. A higher cover of dense forest in the catchment leads to a higher quantity of highly aromatic DOM in the river network, whereas an increasing savannah cover results in lower DOC concentrations and less absorptive DOM. In addition to land cover, the watershed morphology (expressed by the average slope) exerts a strong control on DOC and CDOM in tropical rivers. Our results also show that the percentage of C3 and C4 vegetation cover is not an accurate predictor for DOM and CDOM quality in rivers due to the importance of the spatial distribution of land cover within the drainage network. The comparison of our results with previously published CDOM data in temperate and high-latitude rivers highlights that DOM in tropical freshwaters is generally more aromatic, and shows a higher capacity for absorbing sunlight irradiance. [ABSTRACT FROM AUTHOR]

We analyze past and future trends in nitrogen (N), phosphorus (P), and carbon (C) export by rivers to the coastal waters of Africa as calculated by the Global Nutrient Export to WaterShed (NEWS) models for the period 1970-2050. Between 1970 and 2000 the total nutrient export by African rivers increased by 10-80%. For future years (2000-2050) we calculate an increase in the total loads of dissolved forms of N and P, but decreasing trends for dissolved organic C and particulate forms of N and P. There are large regions that deviate from these pan-African trends. We explore the regional patterns and the underlying processes, in particular for the Nile, Zaire, Niger, and Zambezi. In the future, anthropogenic sources may, in large parts of Africa, become larger contributors to riverine nutrient loads than natural sources. [ABSTRACT FROM AUTHOR]