915 research outputs found
Sorption de l'atrazine et du diuron sur charbon actif en poudre en présence de tensioactifs, ions calcium et bichromate. Essai de modélisation
La contamination des eaux naturelles par les micropolluants organiques tels que les herbicides, nécessite le recours à des procédés trÚs performants, en particulier l'adsorption sur charbon actif pour satisfaire aux normes de potabilité sur les eaux distribuées. Si le charbon actif en poudre (CAP) présente une bonne efficacité pour l'élimination des herbicides seuls dans l'eau distillée, la présence dans l'eau d'autres composés organiques et / ou minéraux aura pour conséquence la modification des paramÚtres de l'équilibre de l'adsorption du systÚme initial et la modification des performances du matériau adsorbant. Cette étude a montré que le CAP utilisé présente une bonne affinité pour les deux herbicides étudiés (atrazine et diuron), dont les capacités d'adsorption, déterminées par le modÚle de Langmuir, sont 1,42 et 1,72 mmol.g-1 respectivement. La présence de composés organiques tels que les tensioactifs anionique le dodécylsulfate de sodium (DSS), et cationique le bromure d'hexadécyl triméthyl ammonium (BHTA) provoque une forte diminution de la capacité d'adsorption des deux herbicides par le charbon actif. Le BHTA provoque l'effet le plus marqué, par contre, les ions calcium et bichromate n'ont pas d'influence sur l'adsorption des deux herbicides. Les essais de désorption ont montré que l'introduction des coadsorbats organiques provoque la désorption d'une partie de l'herbicide. Ce phénomÚne est accentué dans le cas du DSS en présence d'ions calcium. L'application de modÚles simples de coadsorption, a permis de mettre en évidence l'existence presque exclusive de sites spécifiques d'adsorption pour chacun des substrats étudiés et une inhibition non compétitive due a une interdépendance possible entre les sites d'adsorption et une altération des interactions de chaque composé à la surface du charbon.Contamination of natural waters by organic micropollutants like pesticides requires the use of powdered activated carbon (PAC) during the flocculation step of water treatment. One of the main factors affecting the efficiency of this process is the presence in natural waters of organic and mineral compounds. The aim of this study was to determine the influence of two surfactants [(i) anionic (sodium dodecyl sulfate : SDS) and (ii) cationic (hexadecyl-trimethyl ammonium bromide : HTAB)], and two mineral ions (calcium and dichromate) upon atrazine and diuron adsorption on powderd activated carbon resulting from Chemviron Filtrasorb-400. The adsorption capacities on PAC of atrazine and diuron alone were determinated according to the Langmuir model for the isothermes (table I). They were estimated to be 1.42 and 1.72 mmol.g-1 respectly at pH 5.5. Coadsorption results pointed out that the herbicide adsorption was inhibited in the presence of surfactants whatever their nature (fig. 1 and 2).This inhibition was most importante with HTAB (45%), according to the zeta surface potential and the streric dimensions of molecules, than with SDS (23%) for atrazine . The same result was noted for diuron with an inhibition respectly of 15% for SDS and 27% for HTBA. Calcium and dichromate ions, each one with one herbicide had no effect. In any case, Langmuir isothermes were drawn and adsortion capacities were calculated with a good correlation (tables II and III). The influence of coadsorbats was always greatest for atrazine than for diuron. All the experiments were performed at pH=5.5, without influence upon the adsorption, even for the dichromate ions. Desorption tests showed that a part of adsorbed pesticides was desorbed with surfactants introduction (fig. 3) : with SDS 12.3% of atrazine and 8% of diuron against respectly 23% and 17% with HTBA. The phenomenon was increased with SDS in presence of calcium ions (fig. 4 and 5) according to the increase of SDS adsorption (table II and III). The use of two simple coadsorption models was reinforced by the calculated values obtained for adsoartion capacities (fig. 6 and 7) which were very closely with the experimental ones. The calculation of constantes given by the models confirmed the existence of specific sites of adsorption for every compound and a non competitive inhibition due to a change in the nature of the interactions between pesticides and activated carbon surface (table III)
Organic Rural Innovation Systems and Networks: Findings From a Study of Ethiopian Smallholders
Agriculture in Ethiopia is changing. New players, relationships, and policies are influencing the ways in which information and knowledge are used by smallholders. While this growing complexity suggests opportunities for Ethiopian smallholders, too little is known about how these opportunities can be effectively leveraged to promote pro-poor processes of rural innovation. This paper examines Ethiopiaâs smallholder agricultural sector from an innovation systems perspective to understand the changing roles, responsibilities, and interactions of diverse actors in relation to smallholder livelihoods. The paper uses a combination of qualitative and quantitative research tools to paint a picture of the innovation landscape at both the system and local levels. Findings suggest that public sector extension, administration, and related service providers form a closely-knit network in rural Ethiopia with the ability to influence smallholder access to knowledge and information. Given the Government of Ethiopiaâs priorities of improving rural welfare by increasing market access among smallholders, these findings suggest the need for policies and programs designed to strengthen innovative capabilities among rural service providers from the public sector, and to create more space for private and civil society actors to participate in smallholder innovation networks.Ethiopia, Agricultural development, innovation, technology, Social networks, Social learning, Agribusiness, Agricultural and Food Policy, Consumer/Household Economics, Farm Management, Food Consumption/Nutrition/Food Safety, Food Security and Poverty, International Relations/Trade, Marketing, Productivity Analysis, Research and Development/Tech Change/Emerging Technologies,
Influence of Residues Level, Parts and Duration of Decomposition of Some Major Broadleaved Weeds on Germination and Early Seedling Growth of Maize (Zea mays)
A greenhouse experiment was conducted at International Livestock Research institute (ILRI), Wolaita Soddo during 2012-13 with the objective of investigating the effect of soil incorporated Benghal dayflower (Commelina benghalensis L; Commelanaceace) and Thorn apple (Datura stramonium L.; Solanaceae) root and whole plant residues and their duration of decomposition on germination and early growth of maize (Zea mays L.). The soil was unamended and amended with the root and whole plant dry residues at the rate of (5, 10, 20, 40 g/ kg soil) and exposed for three different decomposition periods (0, 2 and 4 weeks) in Completely Randomized Design with 3 replications. None of the treatments was affects the germination of maize significantly. Whereas, the root length of maize seedling was significantly affected by the weed part, amount of residue incorporation and duration of decomposition period and the shoot length and dry matter weight of maize seedling was also significantly affected by the weed part of C. benghalensis, amount of residue incorporation due to both weeds and duration of decomposition period due to D. stramonium 10 days after maize planting. Keywords: Allelopathy, Commelina benghalensis, Datura stramonium, Zea mays, residue decomposition
Influence de l'origine et de la nature des substances humiques sur l'adsorption de l'atrazine sur charbon actif en poudre
Les essais d'adsorption sur charbon actif en poudre, de sept acides humiques (H) ou fulviques (F) et pour trois pH (5,6 ; 7,0 ; 8,8) marquent que ces acides ont un comportement diffĂ©rent suivant leur origine.Lorsque le pH de la suspension de charbon est basique, l'adsorption des diffĂ©rentes fractions humiques diminue, ce qui est en relation avec l'augmentation de leur solubilitĂ©. Pour un mĂȘme pH de la suspension, les acides humiques et fulviques d'origine aqueuse s'adsorbent mieux que ceux d'origine commerciale ou que ceux extraits de sol.La capacitĂ© maximale d'adsorption de l'atrazine sur charbon actif en poudre : 260 mg.g-1 (Langmuir), est plus fortement diminuĂ©e en prĂ©sence d'acides fulviques que d'acides humiques d'une part, et plus inhibĂ©e (jusqu'Ă 40 %) par les acides fulviques extraits d'eau (F1, F2) que par ceux extraits de sol (F3) d'autre part.Par contre, les acides humiques provenant de substances commerciales (H4, H5) influencent moins l'adsorption de l'atrazine.L'ensemble des essais montre que l'origine et la nature des substances humiques joue un rĂŽle prĂ©pondĂ©rant sur l'adsorption de l'atrazine sur charbon actif, le pH ayant une influence limitĂ©e.Enfin l'Ă©tude de l'influence de l'atrazine sur l'adsorption des substances humiques sur charbon actif en poudre indique Ă©galement une diffĂ©rence de comportement entre les acides fulviques, pour lesquels on note peu de variation, et les acides humiques, pour lesquels on note Ă la fois une promotion de l'adsorption et une meilleure affinitĂ© d'adsorption sur le charbon actif en poudre en prĂ©sence d'atrazine.Ce travail met en Ă©vidence l'importance du choix des substances humiques pour des essais d'Ă©valuation des interactions substances humiques - pesticides lors de l'adsorption sur charbon actif en poudre.Though the subject was copiously and oldly studied, this work is bringing a new contribution to the study of the influence of the origin and the nature upon their properties and in particular with atrazine, the more used herbicide these fast years.In order to study this influence of the origin and nature of various humic substances upon the removal of atrazine by adsorption onto powdered activated carbon (PAC), humic substances were obtained from different sources :- Natural aquatic fulvic (F1) and humic (H1) acids isolated from Beaune Lake (Limoges, France).- Natural aquatic fulvic (F2) and humic (H2) acids extracted from hydroxyde sludges of the water treatment plant of La Bastide (Limoges, France).- Soil fulvic acids (F3) extracted from a canadian top soil horizon.- Commercial humic acids (Aldrich. H4 and Jansen H5) obtained from commercial sodium humates.The results of adsorption test of humic acids, fulvic acids and atrazine (alone or together) onto powdered activated carbon (PAC) at three different pH (5,6 ; 7,0 ; 8,8) were expressed by Freundlich's and Langmuirâs models and permitted us to note that :- According to the increasing of water solubility of humic substances with basic pH, their adsorption was better in acidic medium.- Natural aquatic humic substances (H1, H2, F1, F2) were more adsorbed onto PAC than humic substances tram soil (H3) or commercial origines (H4, H5).- Atrazine adsorption capacity was 260 mg.g-1 according to Langmuir's model.- Atrazine adsorption decreased with F1 for all pH ; the same result was also observed with the other natural aquatic humic substances.- Commercial humic acids didnât importantly affect atrazine adsorption. These differences appeared to be derived from the nature and the origin of fulvic and humic acids. The rose of atrazine on the humic substances adsorption showed a difference between humic and fulvic acids whose adsorption was not influenced by atrazine even humic acids only presented an increasing of adsorption.All these results showed the importance of the selection of humic substances to evaluate the interaction SH-Pesticides during adsorption onto PAC and let us think to a competitive adsorption between fulvic acids and atrazine onto PAC
Influence du dodécylsulfate de sodium sur l'adsorption des acides humiques sur charbon actif en poudre
L'objectif de ce travail est d'Ă©tudier l'influence d'un tensioactif anionique, le dodĂ©cylsulfate de sodium (DSS) sur l'adsorption d'acides humiques (AH), sur le charbon actif en poudre (CAP).L'adsorption sur CAP, en fonction du temps, des AH seuls, puis du DSS seul, a Ă©tĂ© effectuĂ©e en rĂ©acteur discontinu, Ă diffĂ©rents pH (7,0 et 10,5). Les mĂȘmes expĂ©riences ont Ă©tĂ© rĂ©alisĂ©es avec le mĂ©lange des deux composĂ©s et l'on a pu constater une inhibition rĂ©ciproque de leur adsorption, moins importante Ă pH basique (10,5).L'influence de l'ordre d'introduction des coadsorbats, sur l'adsorption de chacun d'eux, a permis de montrer que l'inhibition de l'adsorption des AH sur CAP par le DSS est encore plus importante lorsque les AH sont ajoutĂ©s sur une suspension DSS-CAP dĂ©jĂ en Ă©quilibre. Aucune dĂ©sorption du DSS n'a pu ĂȘtre mise en Ă©vidence aprĂšs 24 heures. Ces rĂ©sultats pourraient permettre de conclure Ă une adsorption « compĂ©titive » des AH et du DSS sur les mĂȘmes sites superficiels du charbon actif.Ce travail permet de prĂ©ciser les phĂ©nomĂšnes d'adsorption pouvant intervenir entre divers micropolluants susceptibles de s'adsorber simultanĂ©ment soit sur des sĂ©diments naturels, soit sur charbon actif lors du traitement des eaux naturelles.The removal of humic acids (HA) from natural waters is a very old yet modern problem : humic substances are at the origin of the coloration of water but also, they give off nocive trihalomethanes during chlorination.Humic acids are also known to be a metal micropollutant vector and their behavior is not well defined when there is coadsorption.The purpose of this work was to study the effect of an anionic surfactant, sodium dodecyl sulphate (SDS), on the adsorption on powdered activated carbon (PAC) of humic substances from a commercial source, as a function of the pH (7.0 or 10.5), as well as the effect of the order of introduction of the coadsorbate.Results (fig. 1 to 3 and fig. 6) showed an inhibition of the adsorption for both HA and SDS in the presence of the coadsorbate. The inhibition was more significant for a pH = 7.0.Results of the influence of the order of introduction of the coadsorbate on the adsorption (fig. 4 and 5) showed a more significant inhibition of HA adsorption when HA were introduced into the equilibrium suspension SDS-PAC (the contact lime was 24 hours).Table 1 gives parameter values of the Langmuir equation for the adsorption on PAC of HA atone or with SDS.All these results suggest that a competition on the same sites occurs during the adsorption on PAC of HA and SDS
Ătude de l'adsorption de l'atrazine sur le charbon actif en poudre en prĂ©sence de tensioactifs
Les tensioactifs, adjuvants participant Ă la formulation des pesticides peuvent se trouver en compĂ©tition avec ces derniers lors de l'adsorption sur charbon actif en poudre (CAP) utilisĂ© au cours du traitement de potabilisation des eaux. L'adsorption de l'atrazine, qui reste l'un des produits phytosanitaires le plus souvent dĂ©tectĂ© dans les eaux de surface malgrĂ© les rĂ©glementations sur son utilisation, a Ă©tĂ© Ă©tudiĂ©e en prĂ©sence de trois tensioactifs afin de dĂ©terminer l'influence de ces derniers; il a Ă©tĂ© choisi un tensioactif anionique (DSS), cationique (BHTA), et un non ionique (DE6). Les rĂ©sultats ont montrĂ© que quelle que soit la nature du tensioactif, celui-ci diminue toujours l'adsorption de l'atrazine pour des pH variant de 3,5 Ă 10 ce qui a pour consĂ©quence une diminution Ă la fois de la constante de vitesse (Adams et Bohart) et de la capacitĂ© d'adsorption (Langmuir). L'Ă©tude de l'influence de l'ordre d'introduction des diffĂ©rents Ă©lĂ©ments participant Ă l'adsorption (CAP, atrazine, tensioactif) a montrĂ© que la fixation prĂ©alable de DSS anionique, favorisĂ©e en milieu acide, inhibe davantage l'Ă©limination de l'atrazine. L'application des modĂšles d'adsorption compĂ©titive et non compĂ©titive de Langmuir n'a pas permis de dĂ©finir avec certitude la nature des interactions entre l'herbicide et les diffĂ©rents tensioactifs.Atrazine, in spite of the restrictions concerning its use, remains one of the most prevalent pesticides in natural surface waters. If a sudden pollution incident occurs, powdered activated carbon (PAC) is used during the flocculation step of water treatment; under such circumstances, atrazine might be in adsorption competition with surfactants included in commercial formulations. The aim of this study was thus to determine the influence of three surfactants [anionic (sodium dodecylsulphate, SDS), cationic (hexadecyl-trimethylammonium bromide, HTAB) and nonionic (2-dodecyloxy-pentaethanoxy)-ethanol, DE6)] on atrazine adsorption onto PAC. At pH 5.5, adsorption onto PAC of atrazine alone was estimated to be 230 mg. g-Âč; it was inhibited whatever the nature of the surfactant (cationic anionic or nonionic: figs. 2, 3 and 4). The adsorption capacities (Langmuir) and the kinetic constants (Adams & Bohart) decreased in the presence of the surfactants (table 4) and this diminution was most important for HTAB (fig. 5), perhaps the consequence of a steric effect.The adsorption onto PAC of the molecular form of atrazine (pK=1.68) was not affected by the pH variations. However, when the pH was increased (3.5 to 10) in the presence of SDS, adsorption onto PAC of the anionic surfactant decreased and atrazine adsorption increased (fig. 9). In contrast, for the same experimental conditions but with the cationic surfactant HTAB, adsorption of the surfactant increased over the pH range 3.5 to 10 and the relative adsorption of atrazine diminished (fig. 9). The nonionic surfactant DE6 had no influence.A study of the introduction order of the different components (atrazine, SDS surfactant and PAC) showed the same final equilibrium distribution of atrazine was obtained (fig. 10), regardless of the order of introduction. A similar result was obtained for the adsorption of SDS (fig. 11).For all these cases, the Langmuir equation yielded the adsorption capacity for atrazine and the equilibrium constant. However, competitive and noncompetitive adsorption models (table 1) were unsuccessful in predicting the nature of the interactions between atrazine and the surfactants (table 5)
Adsorption du pentachlorophenol sur divers matériaux : Influence de co-adsorbats organiques (Substances humiques et lindane)
Nous avons rĂ©alisĂ©, pour de faibles concentrations, l'Ă©tude de l'adsoprtion d'un pesticide le pentachlorophĂ©nol, sur plusieurs matĂ©riaux adsorbants : le charbon actif, la kaolinite et la bentone. Les rĂ©sultats montrent que l'adsorption du pentachlorophĂ©nol sur la kaolinite reste nĂ©gligeable tandis que la bentone SD-3 (argile traitĂ©e) permet d'obtenir des rĂ©sultats intĂ©ressants avec toutefois une capacitĂ© maximale d'adsorption 10 Ă 100 fois plus faible que celle du charbon actif. Le charbon actif reste le meilleur matĂ©riau adsorbant pour le pentachlorophĂ©nol. La solubilitĂ© de ce composĂ© Ă©tant trĂšs variable en fonction du pH du milieu on constate que l'adsorption du pentachlorophĂ©nol-pentachlorophĂ©nate (5 mg.l-1) diminue pour des valeurs de pH supĂ©rieures au pKa du couple acide-base que nous avons dĂ©terminĂ© expĂ©rimentalement, Ă©gal Ă 5,9 ± 0,1. L'adsorption du pentachlorophĂ©nol n'est pas affectĂ©e par la prĂ©sence d'acides humiques (obtenus Ă partir de substances commerciales) utilisĂ©s comme coadsorbats (10 mg.l-1) alors que les acides fulviques (20 mg.l-1) extraits de sols semblent provoquer une promotion de l'adsorption. On observe d'autre part que le pentachlorophĂ©nol n'affecte pas l'adsorption des acides humiques mais augmente lĂ©gĂšrement celle des acides fulviques. Ces remarques suggĂšrent la possible formation d'un complexe acides fulviques-pentachlorophĂ©nol. Lorsqu'on utilise le lindane, pesticide hydrophobe comme coadsorbat (165 mg.l-1), on observe encore d'une façon systĂ©matique pour tous les nombreux essais une lĂ©gĂšre promotion de l'adsorption.Adsorption studies for the removal of the pesticide pentachlorophenol found in a number of water supplies (BELAMIE and GIROUD, 1986) were carried out using various materials including kaolinite, bentone SD-3 and powdered activated carbon (WEBER and GOULD, 1966; WEBER and JODELHAH, 1985). It was found that adsorption on kaolinite was negligible, whereas bentone SD-3 presented and adsorption efficiency from 10 to 100-fold less than equivalent quantities of powdered activated carbon (LOTSE et al., 1968; SHAROM et al., 1980). The effect of the pH on the removal of pentachlorophenol by activated carbon was studied. The removal efficiency of pentachlorophenol by activated carbon is better in acidic media. A clear dependence of adsorption on the pH appeared to be the result of a marked variation of the pesticide solubility as a function of the pH (fig. 3). Adsorption of pentachlorophenol/phenate (5mg.l-1) diminishes markedly at pH values above the pKa of this weak acid (that we found equal to 5,9 ± 0,1) when the pentachlorophenol exists almost entirely in ionic form in aqueous solution, and is enhanced at low pH when the percentage of molecular species (whose concentration can be determined from pKa value) becomes significant (WARD and GETZEN, 1970). These remarks and the adsorptive capacities (163 mg.g-1= 0,6 mmol.g-1 at pH = 5,2 and 79 mg.g-1 0,3 mmol.g-1 at pH =12,7), suggest a Đ-Đ interaction between pentachlorophenol and activated carbon which seems to be confirmed by the results with bentone SD-3 (tables 1 to 4), and the values of the electrokinetic potential of these materials. This study emphasizes the effect of organic coadsorbates (e.g., dissolved humic substances and the pesticide lindane) on the adsorption capacity of activated carbon for pentachlorophenol. Two different natural organic matters were studied as coadsorbates : purified humic acids from a commercial source (at 10 mg.l-1) and fulvic acids extracted from a top soil horizon (et 20 mg.l-1) (SCHNITZER and SKINNER, 1963; THURMAN and MALCOLM, 1981). Pentachlorophenol adsorption was not affected by humic acids, whereas an increase of adsorption seemed to be observed in the presence of fulvic acids (fig. 6). Pentachlorophenol does not affect the adsorption of humic acids, but improves slightly the removal of fulvic acids. This suggests an association between the two kinds of organic compounds (WERSNAW et al., 1969; KHAN, 1972; OGNER and SCHNITZER, 1970), the resulting « complex », fulvic acids/pentachlorophenol, being more adsorbed than the compounds themselves. The coadsorbate lindane (0,65 mg.l-1) which is easily adsorbed by activated carton (GOMELLA and BELLE, 1975...) seemed also to Improve slightly the removal efficiency of pentachlorophenol by activated carton (fig. 7)
Prediction of HLA class II alleles using SNPs in an African population
BACKGROUND:
Despite the importance of the human leukocyte antigen (HLA) gene locus in research and clinical practice, direct HLA typing is laborious and expensive. Furthermore, the analysis requires specialized software and expertise which are unavailable in most developing country settings. Recently, in silico methods have been developed for predicting HLA alleles using single nucleotide polymorphisms (SNPs). However, the utility of these methods in African populations has not been systematically evaluated.
METHODOLOGY/PRINCIPAL FINDINGS:
In the present study, we investigate prediction of HLA class II (HLA-DRB1 and HLA-DQB1) alleles using SNPs in the Wolaita population, southern Ethiopia. The subjects comprised 297 Ethiopians with genome-wide SNP data, of whom 188 had also been HLA typed and were used for training and testing the model. The 109 subjects with SNP data alone were used for empirical prediction using the multi-allelic gene prediction method. We evaluated accuracy of the prediction, agreement between predicted and HLA typed alleles, and discriminative ability of the prediction probability supplied by the model. We found that the model predicted intermediate (two-digit) resolution for HLA-DRB1 and HLA-DQB1 alleles at accuracy levels of 96% and 87%, respectively. All measures of performance showed high accuracy and reliability for prediction. The distribution of the majority of HLA alleles in the study was similar to that previously reported for the Oromo and Amhara ethnic groups from Ethiopia.
CONCLUSIONS/SIGNIFICANCE:
We demonstrate that HLA class II alleles can be predicted from SNP genotype data with a high level of accuracy at intermediate (two-digit) resolution in an African population. This finding offers new opportunities for HLA studies of disease epidemiology and population genetics in developing countrie
Understanding Industrial Energy Use through Lean Energy Analysis
Due to rising energy costs and global climate change, many industries seek to improve their energy efficiency. This paper describes a three-step method to analyze utility billing, weather, and production data to understand a companyâs energy performance over time. The method uses regression modeling of utility billing data against weather and production data. The regression models are then driven with typical weather and production data to calculate the ânormal annual consumptionâ, NAC. These steps are repeated on sequential sets of 12 months of data to generate a series of âslidingâ NACs and regression coefficients. The method can quantify successful energy efficiency initiatives and lend insight into the cause of the energy savings. In addition, the method is able to proactively identify energy saving opportunities. The method is demonstrated with a case study. The case study shows that the method is able to disaggregate energy use into weather, production and independent components, accurately measure changes in plant energy efficiency, lend insight into the nature of the those changes, identify savings opportunities and identify changes in overall process control
Spatial and temporal patterns of deformation at the Tendaho geothermal prospect, Ethiopia
Observations of ground deformation in East Africa have been fundamental for unveiling the tectonics of continental rifting, assessing the seismic and volcanic hazard to development, and identifying geothermal resources. Here we investigate the active natural and anthropogenic processes in the Tendaho Graben, Afar using Interferometric Synthetic Aperture Radar (InSAR) collected by the Envisat satellite in 2004â2010. We used the Poly-Interferometric Rate And time series Estimation (Ï-RATE) method to calculate displacement in satellite line-of-sight, and a least-square inversion to decompose the line-of-sight displacement into vertical and rift perpendicular components. We observe two zones of deformation: a 20âŻkm wide circular region of subsidence located 10âŻkm northeast of the town of Semera with a maximum displacement rate of âŒ5âŻcm/yr; and elongated zone (50âŻkm) of subsidence in the area of the geothermal prospect, maximum rate of âŒ4âŻcm/yr. The temporal characteristics of subsidence varies between these zones, with an increase in subsidence rate observed in the circular region in August 2008. We used a Bayesian inversion to find the best fitting source models and compared this to locations of seismicity and other geophysical observations. The pattern of deformation is consistent with a combination of magmatic and geothermal processes, but there does not appear to be a direct link to a sequence of dyke intrusions during 2005â2010 at Manda Hararo graben âŒ60âŻkm away, but dynamic stress changes or deep crustal flow could account for the observations
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