scholarly journals Extreme droughts drive tropical semi-arid eutrophic reservoirs towards CO2 sub-saturation

2018 ◽  
Vol 30 (0) ◽  
Author(s):  
Jurandir Rodrigues de Mendonça Júnior ◽  
André Megali Amado ◽  
Luciana de Oliveira Vidal ◽  
Arthur Mattos ◽  
Vanessa Becker
Keyword(s):  
Carbon Dioxide ◽  
Water Level ◽  
Chlorophyll A ◽  
Co2 Reduction ◽  
Water Volume ◽  
Drought Period ◽  
Autotrophic Metabolism ◽  
Semi Arid Region ◽  
Carbon Dioxide Co2 ◽  
Semi Arid

Abstract Aim: This study aimed to evaluate the carbon dioxide (CO2) dynamics in tropical semi-arid reservoirs during a prolonged drought period as well as to test if the trophic state affects the CO2 saturation. Methods This study was performed in four reservoirs located in the tropical semi-arid region in the northeast of Brazil. All samplings were performed between 9 and 12 am using a Van Dorn Bottle. Samples for partial pressure of carbon dioxide (pCO2 ) measurements were taken in the sub-surface as well as samples for total phosphorus and chlorophyll-a. Correlation analysis and linear regression were used to detect relations among the calculated pCO2, water volume and chlorophyll-a. Results The water level reduction due to atypical droughts caused chlorophyll-a concentrations to increase, which in turn, led to CO2 reduction in the water. However, CO2 concentrations were very variable and an alternation between CO2 sub-saturation and super-saturation conditions was observed. This paper showed that water volume and chlorophyll-a were important regulators of CO2 in the water, as well as important carbon balance predictors in the tropical semiarid reservoirs. Conclusions The results of this paper indicate that the eutrophication allied to drastic water level reductions lead to a tendency of autotrophic metabolism of these systems.

scholarly journals Effectiveness of abundance and biomass curves in detecting environmental alterations in semi-arid region reservoirs

2018 ◽  
Vol 18 (2) ◽  
Author(s):  
Carlinda Raílly Medeiros ◽  
Evaldo de Lira Azevêdo ◽  
José Etham de Lucena Barbosa ◽  
Joseline Molozzi
Keyword(s):  
Arid Region ◽  
Water Resource Management ◽  
Environmental Indicators ◽  
Water Volume ◽  
Severe Drought ◽  
Drought Period ◽  
Littoral Region ◽  
Semi Arid Region ◽  
Effective Diagnosis ◽  
Semi Arid

Abstract For mitigation of environmental problems generated by bad water resource management, the first step is to develop methods for effective diagnosis. The potential bioindicator, mainly in the benthic community, in the evaluation of water quality is the structure of the community, associated with magnitude of environmental impact. The aim of the present study was to evaluate the effectiveness of abundance biomass curves (ABC) as tools to estimate ecological quality in reservoirs in the Brazilian semi-arid region. Two reservoirs, Epitácio Pessoa and Argemiro de Figueiredo were selected. These reservoirs are located in the watershed of the Paraíba River, in Northeast Brazil. Sampling was done at 40 sites in the littoral region of each reservoir, during the periods of higher and lower water volume in the reservoirs. ABC for semi-arid region reservoirs showed disparate results for biological and environmental indicators, because they had a better relationship with momentary variables (physical and chemical parameters). This may be related to the high occurrence of exotic species, principally Corbicula largillierti, which has a high biomass, in association with a severe drought period. ABC must thus be used with parsimony and combined with other indicators, for an accurate and coherent characterization.

Hierarchical three-dimensional copper selenide nanocubes microelectrodes for improved carbon dioxide reduction reaction

2021 ◽  
Author(s):  
Rajasekaran Elakkiya ◽  
Govindhan Maduraiveeran
Keyword(s):  
Carbon Dioxide ◽  
High Performance ◽  
Three Dimensional ◽  
Co2 Reduction ◽  
Value Added ◽  
Carbon Dioxide Reduction ◽  
Reduction Reaction ◽  
Earth Abundant ◽  
Carbon Dioxide Co2 ◽  
Co2 Reduction Reaction

Design of high-performance and Earth-abundant electrocatalysts for electrochemical carbon dioxide (CO2) reduction reaction (CO2RR) into fuels and value-added chemicals offers an emergent pathway for environment and energy sustainable concerns. Herein,...

Low Full‐Cell Voltage Driven High‐Current‐Density Selective Paired Formate Electrosynthesis

2021 ◽  
Author(s):  
Chuqian Xiao ◽  
Ling Cheng ◽  
Yating Wang ◽  
Jinze Liu ◽  
Rongzhen Chen ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
High Current Density ◽  
Co2 Reduction ◽  
Value Added ◽  
Cell Voltage ◽  
High Current ◽  
Oxidation Of Methanol ◽  
Promising Strategy ◽  
Electro Oxidation ◽  
Carbon Dioxide Co2

Anodic selective electro‐oxidation of methanol paring with cathodic carbon dioxide (CO2) reduction is regarded as a promising strategy to generate value added formate product. We firstly design a 3D‐assembled NiCo...

scholarly journals Ichthyofauna diversity of Taperoá II reservoir, semi-arid region of Paraíba, Brazil

2012 ◽  
Vol 72 (1) ◽  
pp. 113-120 ◽  
Author(s):  
AKA Montenegro ◽  
JER Torelli ◽  
MC Crispim ◽  
MIM Hernández ◽  
AMA Medeiros
Keyword(s):  
Diversity Index ◽  
Significant Negative Correlation ◽  
Local Economy ◽  
Water Volume ◽  
Degree Of Dominance ◽  
Similarity Indices ◽  
Semi Arid Region ◽  
One Year ◽  
Number Of Individuals ◽  
Semi Arid

To determine the fish species present in Taperoá II Reservoir, and their relevance to the local economy, this research aimed to evaluate the composition, abundance, degree of dominance and constancy of species, along with diversity, richness, evenness and similarity indices in a tropical semi-arid fish assemblage, during one year. Six 24 hour-long samplings were carried out between October 2005 and October 2006 using cast, seine and gillnets. The 889 collected individuals belonged to 11 species from 9 families. Temporal variation was observed in the capture frequency of different species, and a significant negative correlation between precipitation and number of individuals was also observed. Among the recorded families, Characidae showed a higher frequency of occurrence (38.4%), mostly due to Astyanax bimaculatus (Linnaeus, 1758) and A. fasciatus (Cuvier, 1819). Eight species were categorised as constant, two as accessory and one as accidental. Diversity index values were intermediate with low fluctuation throughout the study period, and no correlation with precipitation or water volume. However, the greatest diversity value was recorded in March 2006, when the peak of the precipitation was recorded. Evenness values showed a similar trend to the diversity index.

scholarly journals Diversity and structure of microcrustacean assemblages (Cladocera and Copepoda) and limnological variability in perennial and intermittent pools in a semi-arid region, Bahia, Brazil

2011 ◽  
Vol 101 (4) ◽  
pp. 317-324 ◽  
Author(s):  
Nadson R. Simões ◽  
Sylvia M. M. S. Ribeiro ◽  
Sérgio L. Sonoda
Keyword(s):  
Electrical Conductivity ◽  
Arid Region ◽  
Suspended Solids ◽  
Diversity Index ◽  
Total Alkalinity ◽  
Water Volume ◽  
Aquatic Environments ◽  
Physical Factors ◽  
Semi Arid Region ◽  
Semi Arid

Temporary wetlands undergo recurrent drought due to the scarcity of water, which disrupts the hydrological connectivity with adjacent aquatic systems. However, some environments retain water for longer periods, allowing greater persistence of the community. The current study evaluated differences in the microcrustacean assemblages and limnological variability between perennial and intermittent pools in a semi-arid region of Brazil. The abiotic features (water temperature, pH, total alkalinity, electrical conductivity and depth) of intermittent pools were affected more than perennial pools due to loss of water volume. This may have contributed to a higher average richness and diversity index in some intermittent pools and differences in the structure of the assemblages. The lowest species richness and diversity were recorded where physical factors, such as a large quantity of suspended solids and variability in the electrical conductivity of the water and pH, make the environment unsuitable for these organisms. These results suggest that community development in intermittent pools is interrupted by the dry season; when the water returns, due to rainfall or rising groundwater, each pond undergoes a different process of colonization. In these circumstances, the biological importance of temporary aquatic environments is clear, since such pools provide shelters and have an important role in the maintenance of the regional diversity of aquatic environments.

scholarly journals Análise de atributos limnológicos em reservatórios do semiárido nordestino

2021 ◽  
Vol 14 (1) ◽  
pp. 357
Author(s):  
Keicyane Alves de Sousa ◽  
Giovana Mira de Espindola ◽  
Carlos Ernando da Silva
Keyword(s):  
Water Quality ◽  
Chlorophyll A ◽  
Total Solids ◽  
Average Temperature ◽  
Temperature And Precipitation ◽  
Full Capacity ◽  
Semi Arid Region ◽  
Semi Arid ◽  
Limnological Parameters

Este trabalho objetiva investigar os parâmetros limnológicos: condutividade, sólidos totais, turbidez, pH, e clorofila-A, de quatro reservatórios multiuso do semiárido nordestino, sendo estes: Barreiras, Bocaina, Estreito e Piaus. Durante os anos de 2018 a 2019, tais reservatório sofreram impactos decorrentes da seca resultando em volumes inferiores a 30% da capacidade total desses reservatórios. Ao longo do período estudado, foram comparados valores obtidos in situ aos valores estabelecidos na resolução CONAMA n° 357/2005 para águas doces de classe II. A correlação linear foi aplicada para verificar as relações entre os parâmetros estudados e fatores naturais como temperatura média e precipitação. A caracterização climática, volumétrica e a ocorrência de seca, foram fatores importantes na discussão dos atributos limnológicos. Os resultados demostram que a ocorrência da seca tem relação com a redução dos volumes dos reservatórios, impactando negativamente na qualidade da água. Os sólidos em suspensão na água foram apontados como determinantes na variação de outros parâmetros, principalmente, da turbidez, da condutividade e do pH. A clorofila-A, variável de grande importância para a qualidade da água, apresentou correlação significativa positiva com precipitação e temperatura. Quanto os valores determinados pelo CONAMA, observou-se que o pH, sólidos totais, e clorofila-A encontram-se com valores superiores ao que é recomendado. A turbidez foi o único parâmetro que se enquadrou dentro do limite de aceitabilidade desta resolução. Os reservatórios Barreiras e Estreito apresentaram os piores valores médios para os parâmetros analisados. Analysis of limnological attributes in northeastern semi-arid reservoirs A B S T R A C TThis work investigates the limnological parameters: conductivity, total solids, turbidity, pH, and chlorophyll-A, from four multipurpose reservoirs in the northeastern semi-arid region of Brazil, namely: Barreiras, Bocaina, Estreito, and Piaus. During the years 2018 to 2019, these reservoirs suffered impacts due to droughts, resulting in volumes below 30% of the reservoirs' full capacity. Over the study period, values obtained in situ were compared to the values established in CONAMA resolution n° 357/2005 for class II freshwater. A linear correlation was applied to verify the relationships between the studied parameters and natural factors such as average temperature and precipitation. Climatic and volumetric characterization and the occurrence of drought were essential factors in the discussion of limnological attributes. The results show that droughts' occurrence is related to the reduction of reservoir volumes, negatively impacting water quality. Suspended solids in water were identified as determining the variation of other parameters, mainly turbidity, conductivity, and pH. Chlorophyll-A, a variable of great importance for water quality, showed a significant positive correlation with precipitation and temperature. Regarding the values determined by CONAMA, it was observed that the pH, total solids, and chlorophyll-A are higher than what is recommended. Turbidity was the only parameter that fell within the acceptability limit of this resolution. The Barreiras and Estreito reservoirs had the worst average values for the analyzed parameters.Keywords: water quality, CONAMA resolution n° 357/2005, drought, semi-arid.

C3 Production from CO2 Reduction by Concerted *CO Trimerization on Single Atom Catalyst

2022 ◽  
Author(s):  
Ling Chen ◽  
Cheng Tang ◽  
Yao Zheng ◽  
Egill Skúlason ◽  
Yan Jiao
Keyword(s):  
Carbon Dioxide ◽  
Carbon Monoxide ◽  
Co2 Reduction ◽  
Single Atom ◽  
Carbon Dioxide Co2

The direct electroreduction of carbon dioxide (CO2) and carbon monoxide (CO) to C3 products is challenging. The main reason is the competitive C2 production resulting from a traditional sequential C–C...

Electrochemical CO2 Reduction to Ethanol: From Mechanistic Understanding to Catalyst Design

2021 ◽  
Author(s):  
Tu Ngoc Nguyen ◽  
Jiaxun Guo ◽  
Ashwini Sachindran ◽  
Fengwang Li ◽  
Ali Seifitokaldani ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Greenhouse Gas ◽  
Electrochemical Reduction ◽  
Co2 Reduction ◽  
Catalyst Design ◽  
Greenhouse Gas Mitigation ◽  
Electrochemical Co2 Reduction ◽  
Mechanistic Understanding ◽  
Carbon Dioxide Co2

The electrochemical reduction of carbon dioxide (CO2) to chemicals is gaining great attention as a pragmatic solution for greenhouse gas mitigation and for the utilization of CO2 to produce useful...

scholarly journals Stabilization Effects in Binary Colloidal Cu and Ag Nanoparticle Electrodes under Electrochemical CO2 Reduction Conditions

Nanoscale ◽  
2021 ◽  
Author(s):  
Longfei Wu ◽  
Kees Kolmeijer ◽  
Yue Zhang ◽  
Hongyu An ◽  
Sven Arnouts ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Electrochemical Reaction ◽  
Co2 Reduction ◽  
Modified Electrodes ◽  
Ag Nanoparticle ◽  
Reaction Conditions ◽  
Electrochemical Co2 Reduction ◽  
Carbon Dioxide Co2 ◽  
Reduction Catalysts ◽  
Sintering Processes

Nanoparticle modified electrodes constitute an attractive way to tailor-make efficient carbon dioxide (CO2) reduction catalysts. However, the restructuring and sintering processes of nanoparticles under electrochemical reaction conditions not only impedes...

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