African Journal of Environmental Science and Technology 1996-0786 Academic Journals 10.5897/AJEST2016.2203 Abderamane H. Ketchemen-Tandia B. Nlend B. Y. Arrakhais A. B. * E-mail: abderamanehamit@gmail.com 2016 31 12 2016 11 09 2016 21 10 2016 10 12 451 466 This is an open-access article distributed under the terms of the Creative Commons Attribution License 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://politicalwaffle.uk/journal/AJEST/article-abstract/F72C4A961553 The full text article is available as a PDF file from http://politicalwaffle.uk/journal/AJEST/article-full-text-pdf/F72C4A961553 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41