Environmental and socioeconomic impacts of cobblestone quarries in Addis Ababa and implication for resource use efficiency,environmental quality,and sustainability of land after‐use

The extraction of construction material in Addis Ababa has been a source of public conflict for many years, especially in terms of quarry operation, displacement of people, rehabilitation of quarry sites, and land after‐use. One of the main reasons for the conflict has been the extraction sector's inability to adjust to the existing laws. This paper reports the findings of a study undertaken to assess the environmental and socioeconomic impacts of quarry mining in Addis Ababa, Ethiopia, and it prescribes interventions that can assist in mitigating the negative impacts of mining. Marked operational, environmental, and socioeconomic impacts have occurred as a result of cobblestone quarrying in Addis Ababa. Improvements in the mitigation of these impacts can be achieved if quarrying operations are planned prior to commencement; resource‐efficient and sustainable mining techniques are employed; stakeholder participation is enhanced; the government provides institutional, organizational, and technical support to the operators; regulations are improved and regulatory implementations receive strict follow‐up; and the provision of the Ethiopian constitution's regarding “rights to development” is respected.     

中小学开展环境教育的方法和途径

在中小学开展环境教育是从根本上解决环境危机、实施可持续发展战略、开展素质教育的需要。本文针对目前中小学环境教育中存在的问题,提出了开展环境教育的方法与途径。     

The Ethiopian mining sector

The Ethiopian Constitution of 1928 vests in the state ownership of all mineral resources. However, the mining code of 1944 recognized the right of individuals and private companies to explore for and develop those resources. The results were quite impressive; Ethiopia became a producer of gold, platinum, copper and other minerals. A revised mining code in 1971 further extended the rights of individuals and companies to develop the mineral resources of the country. In 1974, the newly established revolutionary government eliminated private ownership of mines and established instead state-owned mining companies to develop the mineral resources of the country. In time, the demand for government funding by other sectors of the economy left little for the mining sector and it went into decline. To correct that problem, the Government of Ethiopia in 1989 decided to again make private ownership in the mining sector legal. This paper describes some of the recent initiatives to open the mining sector to private enterprise.     

Optimized pre-treatment of high strength food waste digestate by high content aluminum-nanocluster based magnetic coagulation

Coagulation-based pre-treatment efficiency of high strength digestate of food waste (HSDFW) anaerobic digestion is negated by organic ligand-catalyzed decomposition of coagulants. In this study, an efficient HSDFW pre-treatment method, magnetic seeds (MS) coagulation, was employed by using highly stable Keggin Al₃₀ nanocluster (PAC₃₀), MS and polyacrylamide (PAM), and its operation was optimized by evaluating the performance of removing turbidity, total suspended solids (TSS), chemical oxygen demand (COD), and total phosphorous (TP) phosphate. Results showed that at the optimum dosage of 4.82 g/L, PAC₃₀ demonstrated excellent removals as high as 98.93% ± 0.1% of turbidity, 98.04% ± 0.1% of TSS, 58.28% ± 0.3% of total COD, 99.98% ± 0.01% of TP and 99.50% ± 0.01% of dissolved phosphate, respectively. Apparent molecular weight (AMW) and three-dimensional excitation-emission matrix (3D-EEM) fluorescence spectroscopy analyses demonstrated more efficient removal of dissolved organic matter (DOM), particularly non-biodegradable and hydrophobic components by PAC₃₀ than commercial coagulant. The sedimentation was much improved from 40 min by coagulation/flocculation to about 5 min settling by MS coagulation. The PAC₃₀ based magnetic coagulation (MC) presents theoretical guidance on a cost-effective and much less footprint pre-treatment alternative for high strength wastewater.     

Exposure to DDT and HCH congeners and associated potential health risks through khat (Catha edulis) consumption among adults in South Wollo,Ethiopia

Environmental Geochemistry and Health - Khat (Catha edulis) chewing is widespread in the region of East Africa. Even low levels of organochlorine pesticides (OCPs) in khat could induce public...