title: Metal and physico-chemical variations at a hydroelectric reservoir analyzed by Multivariate Analyses and Artificial Neural Networks: environmental management and policy/decision-making tools.
abstract: This paper compared and evaluated seasonal variations in physico-chemical parameters and metals at a hydroelectric power station reservoir by applying Multivariate Analyses and Artificial Neural Networks (ANN) statistical techniques. A Factor Analysis was used to reduce the number of variables: the first factor was composed of elements Ca, K, Mg and Na, and the second by Chemical Oxygen Demand. The ANN showed 100% correct classifications in training and validation samples. Physico-chemical analyses showed that water pH values were not statistically different between the dry and rainy seasons, while temperature, conductivity, alkalinity, ammonia and DO were higher in the dry period. TSS, hardness and COD, on the other hand, were higher during the rainy season. The statistical analyses showed that Ca, K, Mg and Na are directly connected to the Chemical Oxygen Demand, which indicates a possibility of their input into the reservoir system by domestic sewage and agricultural run-offs. These statistical applications, thus, are also relevant in cases of environmental management and policy decision-making processes, to identify which factors should be further studied and/or modified to recover degraded or contaminated water bodies.
authors.affiliation: Universidade Federal do Pará (UFPA), Instituto de Ciências Exatas e Naturais, Faculdade de Estatística and Faculdade de Ciências da Computação, Rua Augusto Correa, 01, CEP: 66075-110, Belém, PA, Brazil. yurilimacavalcante@gmail.com
authors.forename: Y L
authors.initials: YL
authors.lastname: Cavalcante
authors.forename: R A
authors.initials: RA
authors.lastname: Hauser-Davis
authors.forename: A C F
authors.initials: AC
authors.lastname: Saraiva
authors.forename: I L S
authors.initials: IL
authors.lastname: Brandão
authors.forename: T F
authors.initials: TF
authors.lastname: Oliveira
authors.forename: A M
authors.initials: AM
authors.lastname: Silveira
mesh_terms: D057919:Biological Oxygen Demand Analysis; D001938:Brazil; D055598:Chemical Phenomena; D003658:Decision Making, Computer-Assisted; D004784:Environmental Monitoring / Q000379:methods* / Q000706:statistics & numerical data; D006863:Hydrogen-Ion Concentration; D008670:Metals / Q000032:analysis* / Q000737:chemistry; D015999:Multivariate Analysis; D016571:Neural Networks, Computer; D010100:Oxygen / Q000032:analysis; D011210:Power Plants; D012621:Seasons; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000737:chemistry
chemical_list: D008670:Metals; D014874:Water Pollutants, Chemical; D010100:Oxygen