Environmental factors associated with toxic cyanobacterial blooms across 20 drinking water reservoirs in a semi-arid region of Brazil

Harmful Algae ◽  
2019 ◽  
Vol 86 ◽  
pp. 128-137 ◽  
Author(s):  
Mário U.G. Barros ◽  
Alan E. Wilson ◽  
João I.R. Leitão ◽  
Silvano P. Pereira ◽  
Riley P. Buley ◽  
...  
Keyword(s):  
Drinking Water ◽  
Environmental Factors ◽  
Arid Region ◽  
Cyanobacterial Blooms ◽  
Water Reservoirs ◽  
Factors Associated ◽  
Semi Arid Region ◽  
Semi Arid

scholarly journals Spatio-temporal variation of cyanobacteria and cyanotoxins in public supply reservoirs of the semi-arid region of Brazil

2019 ◽  
Vol 79 (1) ◽  
Author(s):  
Ranielle Daiana dos Santos Silva ◽  
Juliana Santos Severiano ◽  
Dayany Aguiar de Oliveira ◽  
Camila Ferreira Mendes ◽  
Vanessa Virgínia Barbosa ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Secondary Metabolites ◽  
Arid Region ◽  
Cyanobacterial Blooms ◽  
Cylindrospermopsis Raciborskii ◽  
Water Volume ◽  
Public Supply ◽  
Bioactive Secondary Metabolites ◽  
Semi Arid Region ◽  
Semi Arid

Cyanobacteria harmful algal blooms (CyanoHABs) have become increasingly frequent and intense in public supply reservoirs as a result of eutrophication and global climate change. The semi-arid region of Brazil has a well documented history of CyanoHABs but the underlying factors that control the excessive proliferation of these organisms and the production of their bioactive secondary metabolites are not comprehensively understood. This study aimed to identify the environmental factors that explain the spatial and temporal variations in the abundance of cyanobacteria and the concentration of cyanotoxins (microcystins, saxitoxins, and cylindrospermopsin) in semi-arid reservoirs. The following hypotheses were tested: (a) the largest biovolumes of potential toxin producing cyanobacteria occur when cyanotoxin concentrations are highest; and (b) the environmental factors that explain variations in biovolume of cyanobacteria also explain changes in cyanotoxins concentrations. Samples were taken from four reservoirs located in the Northeast region of Brazil, over a three-month period (October 2016 and February and June 2017). Of the 24 species of cyanobacteria identified, 13 were potentially toxin-producing. Physicochemical variables such as water volume of the reservoir, water transparency, soluble reactive phosphorus, and total phosphorus explained the abundance of cyanobacteria and the levels of cyanotoxins. These results corroborate the hypothesis that similar physicochemical conditions influence the abundance and diversity of cyanobacteria and cyanotoxins. Cyanobacterial blooms composed of more than one potential toxin producing species were observed in the studied reservoirs, where potential microcystin-producing species were the most common. Microcystins and saxitoxins were detected in all the reservoirs studied, while cylindrospermopsin and the cyanobacterium Cylindrospermopsis raciborskii were simultaneously recorded in only one reservoir (Camalaú Reservoir). Cylindrospermopsin was only detected in a reservoir for the first time in the State of Paraíba. Canonical redundancy analysis showed that the cyanotoxins were related to potential toxin producing species. These results corroborate the proposed hypothesis that there is a correlation between cyanotoxins and the biomass of potential producers. Also, there were situations where cyanotoxins were detected without the presence of potential producers. These results demonstrate the need for reassessment of potential toxin producing species of cyanobacteria in semi-arid reservoirs. This may lead to the identification and characterization of novel producers of these bioactive secondary metabolites.

Assessment of the geometry and volumes of small surface water reservoirs by remote sensing in a semi-arid region with high reservoir density

2019 ◽  
Vol 64 (1) ◽  
pp. 66-79 ◽  
Author(s):  
Bruno Pereira ◽  
Pedro Medeiros ◽  
Till Francke ◽  
Geraldo Ramalho ◽  
Saskia Foerster ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Surface Water ◽  
Arid Region ◽  
Water Reservoirs ◽  
Small Surface ◽  
Semi Arid Region ◽  
Semi Arid

scholarly journals Assessment of Salinity and Fluoride in Groundwater of Semi-Arid Region of Punjab, India

2017 ◽  
Vol 12 (1) ◽  
pp. 34-41 ◽  
Author(s):  
Gopal Krishan ◽  
M. S Rao ◽  
C. P Kumar ◽  
Sudhir Kumar ◽  
R. S Loyal ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Drinking Water ◽  
Human Health ◽  
Arid Region ◽  
Permissible Limit ◽  
Groundwater Levels ◽  
Groundwater Samples ◽  
Semi Arid Region ◽  
Semi Arid ◽  
Who 2008

Groundwater is the major source of drinking water in Southwestern semi-arid region of Punjab, India which is now facing severe salinity and fluoride (F-) problems. A study was carried out in the Bathinda district of southwest semi-arid region of Punjab to assess the salinity and F- concentrations. Groundwater samples from 21 locations were analyzed, and 59% were found to exceed the permissible electrical conductivity (EC) limit of 1500 µS/cm1. Fluoride concentrations exceeded the WHO (2008)1 permissible limit of 1.50 mg/L in 69% of the samples which may significantly affect human health by causing fluorosis. The increase in groundwater levels leading to high evaporation which caused an accumulation of salts and further resulted in increase in EC. The increased F- concentration is mainly due to rock-water interactions which led to fluorite dissolution.

Effects of environmental factors on the distribution of plant communities in a semi-arid region of the Qinghai-Tibet Plateau

2012 ◽  
Vol 27 (4) ◽  
pp. 667-675 ◽  
Author(s):  
Zeng-Ru Wang ◽  
Guo-Jing Yang ◽  
Shu-Hua Yi ◽  
Sheng-Yun Chen ◽  
Zhen Wu ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Plant Communities ◽  
Arid Region ◽  
Tibet Plateau ◽  
Semi Arid Region ◽  
Qinghai Tibet Plateau ◽  
Semi Arid

scholarly journals STATISTICAL ANALYSIS OF THE SPATIAL RELASHIONSHIP OF CAATINGA AND PHYSIOGRAPHIC FACTORS THROUGH REMOTE DATA

FLORESTA ◽  
2019 ◽  
Vol 49 (4) ◽  
pp. 755
Author(s):  
Janisson Batista de Jesus ◽  
Mariana Mizutani Ribeiro ◽  
Tatiana Mora Kuplich ◽  
Bruno Barros de Souza ◽  
Dráuzio Correia Gama
Keyword(s):  
Spatial Distribution ◽  
Statistical Analysis ◽  
Arid Region ◽  
Factors Associated ◽  
Independent Variables ◽  
Caatinga Vegetation ◽  
Semi Arid Region ◽  
Relationship Of ◽  
The Relationship ◽  
Semi Arid

The caatinga is characteristic of the semi-arid region of Brazil, of significant coverage in the northeast of the country and, therefore, geoprocessing and statistical techniques can be important tools to analyze the environmental factors associated with its distribution. The present study had the objective of analyzing the relationship of: altimetry, slope, soil type and river proximity in the spatial distribution of the caatinga vegetation, using a database generated by geoprocessing techniques. NDVI was used, and statistical analysis was based on multiple regression and Pearson's correlation. The results show that the weather station is the only variable that presented a high determination coefficient with the caatinga vegetation (R2 = 0.956), while the other independent variables have weak or nonexistent correlation. With the techniques of geoprocessing was allowed to observe that the Caatinga has a generalist spatial distribution of occurrence, not having a defined pattern.

Prevalence and risk factors associated with swine gastrointestinal nematodes and coccidia in the semi-arid region of northeastern Brazil

2019 ◽  
Vol 52 (1) ◽  
pp. 379-385 ◽  
Author(s):  
Hosaneide Gomes de Araújo ◽  
Juliana Trajano da Silva ◽  
Felipe Boniedj Ventura Álvares ◽  
Larissa Claudino Ferreira ◽  
Sérgio Santos Azevedo ◽  
...  
Keyword(s):  
Risk Factors ◽  
Arid Region ◽  
Gastrointestinal Nematodes ◽  
Northeastern Brazil ◽  
Factors Associated ◽  
Semi Arid Region ◽  
Semi Arid
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