Determinant variables on the isotopic values of particulate organic matter in a neotropical floodplain

Particulate organic matter(POM)is an important energy source for aquatic consumers,understanding its origin and composition is essential for understanding the energetic dynamics of aquatic environments.The aim of this study was to analyze the relationship between POM and phytoplankton(isotopic values and chlorophyll concentration)and abiotic variables during dry and rainy seasons.Sampling was conducted in rivers and lagoons in the floodplain of the Upper ParanáRiver.We found a greater difference in ^(δ13)C values of POM between sampling points than between seasons,indicating that the composition of regional sources influences the composition of POM more than dry and rainy seasons.In addition,the concentration of chlorophyll during the dry season was positively correlated with ^(δ13)C values during that rainy period.Additionally,we found a relationship between factors limiting the growth of phytoplankton and ^(δ13)C values of POM,such as phosphate ions,indicating that variables that regulate phytoplankton growth tend to influence the composition of POM in river floodplains.Therefore,maintaining the variables that regulate the phytoplankton community is of fundamental importance for the composition of POM,an important energy source in aquatic environments.

Levels of Trihalomethanes in Stored Water from High and Fundamental Schools:Comparison between Two Temporal Data Sets

Epidemiological studies have been investigating the relationship between chlorination byproducts exposure and cancer. Studies showed the incidence of colon, rectum and bladder cancer in laboratory animals when halogenated byproducts were administered to them, such as trihalomethanes. Based on this fact, in this work, two data sets of water quality parameters were analyzed with focus on total trihalomethanes (THMt). These two data sets are from two different time periods (one in 2014 and other in 2017). All the samples were collected in the same months, in both data sets. The samples were taken from its same corresponding sampling points in both periods of time. Trihalomethanes (THMs) are undesired byproducts of chlorination and its formation occurs when the chlorine used in water treatment reacts with natural organic matter, which is present in natural waters, during the disinfection process. The aim of this research was to investigate the THMs levels in storage water from the chlorination performed by the Water Treatment Station (WTS) of the Maringá-Parana-Brazil;also, to compare the results obtained with the maximum allowable values (MAVs) established by the Consolidation Resolution n.05/2017, current law of water quality in Brazil. Water samples were collected in eight high and fundamental schools of Maringá-Paraná-Brazil and analyzed through the gas chromatography method by the use of mass spectrometry detector with purge-and-trap concentrator (GC-MS) for THM. Furthermore, parameters such as pH and residual chlorine were analyzed following the methodology proposed by the Standard Methods for the Examination of Water and Wastewater. The study results to THMt show that the maximum value of 21.5 μg/L obtained is within the MAV of 100 μg/L. Chloroform was the compound with higher concentrations in all samples in THMt analysis. Results of residual chlorine and pH also are within the MAVs. Studies like this are important to continuous monitoring of the water quality distributed to population.

Waste Tire Rubber-based Refrigerants for Solid-state Cooling Devices

Management of discarded tires is a compelling environmental issue worldwide.Although there are several approaches developed to recycle waste tire rubbers,their application in solid-state cooling is still unexplored.Considering the high barocaloric potential verified for elastomers,the use of waste tire rubber(WTR)as a refrigerant in solid-state cooling devices is very promising.Herein,we investigated the barocaloric effects in WTR and polymer blends made of vulcanized natural rubber(VNR)and WTR,to evaluate its feasibility for solid-state cooling technologies.The adiabatic temperature changes and the isothermal entropy changes reach giant values,as well as the performance parameters,being comparable or even better than most barocaloric materials in literature.Moreover,pure WTR and WTR-based samples also present a faster thermal exchange than VNR,consisting of an additional advantage of using these discarded materials.Thus,the present findings evidence the encouraging perspectives of employing waste rubbers in solid-state cooling based on barocaloric effects,contributing to both the recycling of polymers and the sustainable energy technology field.