Aim: Water quality has been the subject of many recent studies, moreover, the physical, chemical and biological parameters of water are used to investigate water quality and can be combined into a single index, the Water Quality Index (WQI), for use by water resource managers and the general public. The aim of this study was to use scientometrics to evaluate how water quality has been addressed in the international scientific literature. Method: For the quantitative analysis of the publications on WQI, we used the search database SCOPUS (http://www.scopus.com). The search was performed using the words "QUALIT* WATER* INDEX*" in papers published in all databases (through 2011). Results: We found 554 articles that dealt with the use of WQI the number of publications has increased significantly over the last 20 years. India had the most studies, with 177 articles, followed by China, Brazil and the United States. These four countries together published 57% of studies on WQI. We generated 15 linear models to explain the number of publication by study sit (country). According to the Akaike Information Criterion (AIC), the best model to explain the number of publications by country was the model that combined Sanitation and Public Supply. Conclusion: Finally, this paper presents the state of scientific literature on WQI and demonstrates the growing interest of the scientific community in this issue, which is certainly due to the importance of the quantity and quality of water for human supply, economics, health and the conservation of water resources.Keywords: scientometrics, river, stream, NSF, sanitation, water supply.Resumo: Objetivo: A qualidade da água tem sido objeto de muitos estudos recentes, além disso, os parâmetros físicos, químicos e biológicos da água são usados para investigar a qualidade da água e podem ser combinados em um único índice, um Índice de Qualidade de Água (IQA), para uso de recursos hídricos gestores e público em geral. O objetivo deste estudo foi utilizar a cienciometria para avaliar como a qualidade da água tem sido abordada na literatura científica internacional. Método: Para a análise quantitativa das publicações sobre IQA, foi utilizada a pesquisa de banco de dados SCOPUS (http://www.scopus.com). A pesquisa foi realizada utilizando as palavras "QUALIT* WATER* INDEX*", em artigos publicados em todos os bancos de dados (até 2011). Resultado: Encontramos 554 artigos que tratavam do uso de IQA, e o número de publicações aumentou significativamente ao longo dos últimos 20 anos. A Índia teve o maior número de estudos, com 177 artigos, seguidos por China, Brasil e Estados Unidos. Esses quatro países juntos publicados 57% dos estudos sobre IQA. Geramos 15 modelos lineares para explicar o número de publicação de estudo por país. De acordo com o Critério de Informação de Akaike (AIC), o melhor modelo para explicar o número de publicações por país foi o modelo que combinou Saneamento e Abastecimento Público. Discussão: Finalmente, este trabalho apresenta o estado da literatura científica...

Aim This study aimed to investigate the relative influence of climate (temperature and precipitation) and land use on limnological features of 30 floodplain lakes in the Araguaia River, in Central Brazil, an important river that drains in the Brazilian Cerrado. Methods The lakes were sampled in one same period, at a large spatial scale (900 km along the river) covering climate and landscape variability. For decomposing the relative importance of land use and climate, we used the RDA and partitioning variance techniques. Results The lakes presented limnological gradient along the floodplain; in general, the lakes presented low transparency, nutrients concentrations (total nitrogen and total phosphorus) and oxygen saturation. The water pH was considered weakly acidic. Considering land use in Araguaia river basin, lakes in downstream presented more remnant vegetation and lakes in upstream presented more livestock and agriculture soil use. The climate conditions were the most important in explaining the variation in limnological characteristics of the lakes, while the individual analysis of limnological variables showed that land use was important to explain to the pH and transparency of the water. Conclusions Finally, this study showed the importance of investigating regional climatic attributes and land use information to explain the limnological characterization of floodplain lakes. Thus, it highlights the importance of the possible impacts of global climate change on limnological conditions.

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ABSTRACT:Chlorophyll is a green pigment common to all photosynthetic cells of autotrophic organisms in aquatic or terrestrial environments. Techniques used to quantify this pigment include fluorescence, UV spectrophotometer, chromatography, HPLC, and remote sensing. Determination of the photosynthetic pigment chlorophyll -a (Chl-a), has been used widely in many areas of science. The present study investigated the state of the global scientific literature on Chl-a, determining the countries, approaches, and environments where Chl-a has been studied and the geographic scale used. To obtain this scientometric information, we conducted a study from the Scopus database over a 21-year period from 1990 through 2011. This period saw significant increases in the number of publications (r=0.84 and P< 0.001), different journals where publications appeared (160 journals), major papers with a multidisciplinary character, and a predominance of descriptive approaches with studies conducted in aquatic and marine habitats at a regional scale. The country with the highest number of publications was China (21.64% of total papers; location of study), and the USA had the highest number of authors (19.52% of total papers). The main determining factor for publications was socioeconomic (according to model selection criteria; AIC). This study highlight the multidisciplinary use of Chl-a, and may give some directions to new studies about this pigment.