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Impact of Altitude and Land Use Type on Some Physical and Chemical Properties of Acidic Soils in Tsegede Highlands, Northern Ethiopia

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Open Journal of Soil Science 2012年第3期2卷 223-233页

作者： Abreha Kidanemariam heluf gebrekidan Tekalign Mamo Kibebew Kibret Haramaya University School of Natural Resource Management and Environmental Science Haramaya Ethiopia inistry of Agriculture and Rural Development Addis Ababa Ethiopia

A study was conducted in the Tsegede highlands of Tigray Region, northern Ethiopia to determine the changes in some physical and chemical attributes across three adjacent acidic soil sites with different elevation and three land use types. Analytical results of the collected surface layer soil samples showed significant (P ≤ 0.05) correlation of soil bulk density, OM and total N with elevation. In the lower elevation site (Indaslasie), soil OM content declined by about 43 and 52% compared with that of the two higher elevation sites (Cheguarcudo and Indamariam), respectively. Soil pH, exchangeable acidity, exchangeable Al, OM, total N and available phosphorus also exhibited significant (P ≤ 0.05) disparity across the three land use types of the area. Soils of the forest land were less acidic by 0.43 and 0.68 pH units than the cultivated and grazing lands, respectively. The soil OM content of the cultivated land was significantly lower by about 25 and 35% than the grazing and forest land soils, respectively. Available soil P status was low and showed significant correlations with pH (r = 0.65), exchangeable acidity (r = –0.58) and Al (r = –0.53). In general, the study results revealed altitude did not impose any significant effect in aggravating soil acidity whereas land use type affected significantly not only soil acidity but also the important soil fertility related parameters such as OM, total N and available P contents. Therefore, it can be suggested that besides to the usual acid soil management and/or reclamation practices, introducing proper land use management systems are of paramount importance.

关键词： Acidic Soil Altitude Variability Highland Land Use Type

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Microstructure and Properties of the Cr–Si–N Coatings Deposited by Combining High-Power Impulse Magnetron Sputtering(HiPIMS) and Pulsed DC Magnetron Sputtering

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Acta Metallurgica Sinica(English Letters) 2017年第7期30卷 688-696页

作者： Tie-Gang Wang Yu Dong Belachew Abera gebrekidan Yan-Mei Liu Qi-Xiang Fan Kwang Ho Kim Tianjin Key Laboratory of High Speed Cutting and Precision Manufacturing Tianjin University of Technology and Education Global Frontier R&D Center for Hybrid Interface Materials Pusan National University

The Cr–Si–N coatings were prepared by combining system of high-power impulse magnetron sputtering and pulsed DC magnetron sputtering. The Si content in the coating was adjusted by changing the sputtering power of the Si *** virtue of electron-probe microanalysis, X-ray diffraction analysis and scanning electron microscopy, the influence of the Si content on the coating composition, phase constituents, deposition rate, surface morphology and microstructure was investigated systematically. In addition, the change rules of micro-hardness, internal stress, adhesion, friction coefficient and wear rate with increasing Si content were also obtained. In this work, the precipitation of silicon in the coating was *** increasing Si content, the coating microstructure gradually evolved from continuous columnar to discontinuous columnar and quasi-equiaxed crystals; accordingly, the coating inner stress first declined sharply and then kept almost constant. Both the coating hardness and the friction coefficient have the same change tendency with the increase of the Si content, namely increasing at first and then decreasing. The Cr–Si–N coating presented the highest hardness and average friction coefficient for an Si content of about 9.7 at.%, but the wear resistance decreased slightly due to the high *** above phenomenon was attributed to a microstructural evolution of the Cr–Si–N coatings induced by the silicon addition.

关键词： Cr–Si–N coating High-power impulse magnetron sputtering(HiPIMS) Pulsed DC magnetron sputtering Mechanical property Friction coefficient

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Current and future predicting potential areas of Oxytenanthera abyssinica(***)using MaxEnt model under climate change in Northern Ethiopia

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Ecological Processes 2020年第1期9卷 59-73页

作者： Yikunoamlak Gebrewahid Selemawi Abrehe Esayas Meresa Gebru Eyasu Kiros Abay Gebrehiwot Gebreab Kiros Kidanemariam Gezu Adissu gebrekidan Abreha Girmay Darcha Mekelle Agricultural Research Center(MARC) Tigray Agricultural Research Institute(TARI)P.O.Box 256TigrayEthiopia Mekelle Soil Research Center(MSRC) Tigray Agricultural Research Institute(TARI)P.O.Box 1070TigrayEthiopia Humera Agricultural Research Center(HuARC) Tigray Agricultural Research Institute(TARI)P.O.Box 62TigrayEthiopia Abergele Agricultural Research Center(AARC) Tigray Agricultural Research Institute(TARI)P.O.Box 44TigrayEthiopia Shire-Mytsebri Agricultural Research Center(SmARC) Tigray Agricultural Research Institute(TARI)P.O.Box 241TigrayEthiopia

Introduction:Climate change will either improve,reduce,or shift its appropriate climatic habitat of a particular species,which could result in shifts from its geographical *** the potential distribution through MaxEnt modeling has been developed as an appropriate tool for assessing habitat distribution and resource conservation to protect bamboo ***:Our objective is to model the current and future distribution of Oxytenanthera abyssinica(***)based on three representative concentration pathways(RCP)(RCP2.6,RCP4.5,and RCP8.5)for 2050s and 2070s using a maximum entropy model(MaxEnt)in Northern *** modeling procedure,77 occurrence records and 11 variables were retained to simulate the current and future distributions of Oxytenanthera abyssinica in Northern *** evaluate the performance of the model,the area under the receiver operating characteristic(ROC)curve(AUC)was ***:All of the AUCs(area under curves)were greater than 0.900,thereby placing these models in the“excellent”*** jackknife test also showed that precipitation of the coldest quarter(Bio19)and precipitation of the warmest quarter(Bio18)contributed 66.8%and 54.7%to the *** the area of current distribution,1367.51 km2(2.52%),7226.28 km2(13.29%),and 5377.26 km2(9.89%)of the study area were recognized as high,good,and moderate potential habitats of Oxytenanthera abyssinica in Northern Ethiopia,and the high potential area was mainly concentrated in Tanqua Abergele(0.70%),Kola Temben(0.65%),Tselemti(0.60%),and Tsegede(0.31%).Kafta Humera was also the largest good potential area,which accounts for 2.75%.Compared to the current distribution,the total area of the high potential regions and good potential regions for Oxytenanthera abyssinica under the three RCPs(RCP2.6,RCP4.5,and RCP8.5)would increase in the 2050s and ***,the total area of the least potential regions under the three RCPs(RCP2.6,RCP4.5,and RCP8.5)in 2050s and 2070s would

关键词： Oxytenanthera abyssinica MaxEnt model Climate change

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<i>Acacia etbaica</i>as a Potential Low-Cost Adsorbent for Removal of Organochlorine Pesticides from Water

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Journal of Water Resource and Protection 2015年第3期7卷 278-291页

作者： Abraha gebrekidan Mekonen Teferi Tsehaye Asmelash Kindeya Gebrehiwet Amanual Hadera Kassa Amare Jozef Deckers Bart Van Der Bruggen Department of Chemistry Mekelle University Mekelle Ethiopia Department of Biology Mekelle University Mekelle Ethiopia Department of Microbiology Mekelle University Mekelle Ethiopia Department of Land Resource Management & Environmental Protection Mekelle University Mekelle Ethiopia Department of Earth Science Mekelle University Mekelle Ethiopia Department for Earth and Environmental Science KU Leuven Leuven Belgium Department of Chemical Engineering Process Engineering for Sustainable Systems (ProcESS) KU Leuven Leuven Belgium

The presence of pesticides in the environment is of great concern due to their persistent nature and chronic adverse effect on human health and the environment. Water bodies are subject to pollution by organochlorine pesticides, especially in developing countries, where water pollution is a key sustainability challenge. Hence, activated carbon is considered a universal adsorbent for the removal of organochlorine pollutants from water. Activated carbon from Acatia etbaica was prepared using traditional kilns with low investment costs. Pesticides such as aldrin, dieldrin and DDT were selected for adsorption because of their common usage in agricultural and malaria control activities and may occur in high concentrations in surface waters that are used as drinking water sources. The effect of the adsorbent dose and initial concentration were investigated. To describe the equilibrium isotherms the experimental data were analyzed by the Langmuir and Freundlich isotherm models. The Freundlich model gave the best correlation with the experimental data. Activated carbon prepared from Acacia etbaica was found to be an effective and low-cost alternative for the removal of organochlorine pesticides from aqueous solutions. The preparation method allows the use of this material by local communities for effective remediation of pollution by pesticides.

关键词： Acacia etbaica Activated Carbon Organochlorine Pesticides Adsorption Water Purification

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