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Being energy-autonomous has been suggested as a means of having sustainable energy in South Africa, where about 98% of electricity is derived from coal. Research has shown that biogas produced from animal wastes using a biodigester can be used as a source of renewable energy with the added benefits of a by-product called digestate, which can replace inorganic fertiliser. This study analyses the factors that influence smallholder farmers' willingness to adopt a biodigester technology. It uses a structured questionnaire to acquire data from 80 respondents in Ngaka Modiri Molema District in North West Province, South Africa. The respondents were 30 livestock farmers and 29 farmers practising mixed farming. Five extension officers were also interviewed to establish their level of knowledge about the technology. Descriptive statistics and Fisher's exact test were used to analyse the data. Factors such as gender, years of experience and family size were significant to willingness to adopt a biodigester. Farmers who were male and those with more years of experience were open to the idea, while those with larger families were less open to it, due to financial constraint. Overall, respondents practising mixed farming were more willing to adopt a biodigester than livestock farmers. [ABSTRACT FROM AUTHOR]

Distribution and equilibrium partitioning of metals (Cd, Cu, Cr, Fe, Ni, Pb, Mn, and Zn) between pore water and surface sediments at the Ilaje coast of Ondo State, Nigeria, were studied. The Ilaje River can be one of the interesting research locations because of its economic nature and history of oil pollution. Seasonal variations were observed to investigate possible variations in the availability of metals for organisms throughout the year. The concentrations in both sediments and pore water during the dry and wet seasons were as follows: Cu > Fe ⋙ Mn > Pb > Ni > Cr > Cd > Zn. The pore water-sediment partition coefficient (Kp) showed that Zn and Cd were highly mobile while Fe and Cu have restricted mobility. Dissolved organic carbon (DOC) in pore water had a strong influence on mobility and bioavailability of all the metals (p < 0.05) except Cr whose concentration was pH and DOC-dependent. Based on the normalized organic carbon partitioning coefficient (Koc), increased levels of Fe and Cu were linked to lithological origin. Concentrations of Pb and Ni were associated with petroleum-related sources. The significance of the field-based techniques for ecotoxicological purposes is discussed. [ABSTRACT FROM AUTHOR]

Leachate migration from open landfills is an environmental concern of developing cities. This study investigated the base soil-profile pedo-physical and chemical properties of the South African Sepane soil form or referred to as Cutanic Luvisol at the Bloemfontein southern landfill under the Mangaung municipality in the Free State Province. Six soil-profiles pedo-physical, exchangeable-cations and heavy metals concentrations were characterized from in-situ , core and loose soil-samples. The DTPA Test from a 5g air-dried soil extracted heavy metals. The soil profile was characterized by a layered Orthic-A, pedocutanic B- and C-horizons with lower horizons containing mean-total clay of 72%, bulk-density (≥1.5 gcm -3 ) and saturated hydraulic-conductivity (Ks < 6mmhr -1 ). Mean soil pH increased with depth from 6.4 to 6.8 along-side exchangeable-cations ranging from 19 to 2573 mgkg -1 in the order Ca > Mg > K > Na > S > P and Ca > Mg > Na > K > S > P for the respective A- and B-horizons. The Mg/K and (Ca + Mg)/K exceeded norm ratios. Soil-profile horizons had respective 44%, 34% and 22% heavy-metal distribution with mean content range of 0.001-37.3 mgkg -1 in the order Mn > Fe > Cr > Zn > Cu > As > Pb > Ni > Cd and Fe > Mn > Cr > Cu > As > Pb > Zn > Ni > Cd for the surface and subsurface horizons, respectively. Heavy-metal mean concentrations were below the norm except for Cr that was higher than 150% from upper horizons and posed serious risk to the near-surface environment. Soil profiles heavy-metal content and pollution-index was unpolluted (0.3-0.4), decreased with depth and reflected no subsurface pollution concerns. This study findings highlighted low internal-migration potential of clay soils and the need for understanding the sources and mode of migration of Cr at the landfill alongside continued monitoring., (© 2019 The Author(s).)

In recent decades, drought has been identified as part of the several regular climate-related hazards happening in many African countries including South Africa, often with devastating implications on food security. Studies have shown that the earth temperature has increased over the recent years which can trigger drought occurrences and other climate-related hazards. Drought occurrence is principally a climate-related event that cannot be totally effaced though it can be managed. This study is aimed at appraising drought severity in Cape Town area, South Africa using Geographic Information System (GIS) and remotely sensed data obtained from United States Geological Survey (USGS) database between the years 2014 and 2018. The study revealed that the land use dynamics witnessed drastic changes where vegetation, water body and bare surface decreased from 2095 to 141 km 2 , 616 to 167 km 2 and 2337 to 1381km 2 respectively while built up and sparse vegetation increased from 5301 to 8191 km 2 and 7382-7854 km 2 during the period. Vegetation health and drought severity of the study area was assessed using vegetation indices and Normalized Drought Dryness Index (NDDI). The result reveals that Normalized Difference Water Index (NDWI) and other vegetation indices decreased considerably more in recent years (2017 and 2018) which might have triggered drought events during the period compared to the other years (2014-2016). Furthermore, the spatial trend of land surface temperature (LST) and NDDI increased in recent years with NDDI values ranging between moderate drought and severe drought threshold. Consequently, if the increment persists, it can lead to adverse impacts such as food insecurity, land degradation and environmental health deterioration. Evidently, this study reveals the current state of vegetation health regarding drought severity in the area using remotely sensed data.