Evidence of reproductive disturbance in Astyanax lacustris (Teleostei: Characiformes) from the Doce River after the collapse of the Fundão Dam in Mariana,Brazil

Environmental Science and Pollution Research - The Fundão Dam collapsed, on November 5th, 2015, dumping more than 50 million/m3 of iron ore tailings, enriched with metals, into the Doce River...     

Inflammation biomarkers associated with arsenic exposure by drinking water and respiratory outcomes in indigenous children from three Yaqui villages in southern Sonora,México

Environmental Science and Pollution Research - Environmental arsenic exposure in adults and children has been associated with a reduction in the expression of club cell secretory protein (CC16) and...     

Steel mill waste application in soil: dynamics of potentially toxic elements in rice and health risk perspectives

Environmental Science and Pollution Research - Potentially toxic elements (PTEs) are of great concern in steel mill wastes. Therefore, in order to use them as potential fertilizers in soil, risk...     

Glyphosate concentrations in global freshwaters: are aquatic organisms at risk?

Environmental Science and Pollution Research - Glyphosate is the most used herbicide worldwide. Many studies have reported glyphosate risks to aquatic organisms of different trophic levels....     

Artificial light at night (ALAN) causes variable dose-responses in a sandy beach isopod

Artificial Light at Night (ALAN) is expanding worldwide, and the study of its influence remains limited mainly to documenting impacts, overlooking the variation in key characteristics of the artificial light such as its intensity. The potential dose–response of fitness-related traits to different light intensities has not been assessed in sandy beach organisms. Hence, this study explored dose-responses to ALAN by exposing the intertidal sandy beach isopod Tylos spinulosus to a range of light intensities at night: 0 (control), 20, 40, 60, 80 and 100 lx. We quantified the response of this species at the molecular (RNA:DNA ratios), physiological (absorption efficiency) and organismal (growth rate) levels. Linear and non-linear regressions were used to explore the relationship between light intensity and the isopod response. The regressions showed that increasing light intensity caused an overall?~?threefold decline in RNA:DNA ratios and a?~?threefold increase in absorption efficiency, with strong dose-dependent effects. For both response variables, non-linear regressions also identified likely thresholds at 80 lx (RNA:DNA) and 40 lx (absorption efficiency). By contrast, isopod growth rates were unrelated (unaltered) by the increase in light intensity at night. We suggest that ALAN is detrimental for the condition of the isopods, likely by reducing the activity and feeding of these nocturnal organisms, and that the isopods compensate this by absorbing nutrients more efficiently in order to maintain growth levels.

     

Solar heterogeneous photocatalytic degradation of phenol on TiO2/quartz and TiO2/calcite: a statistical and kinetic approach on comparative efficiencies towards a TiO2/glass system

Environmental Science and Pollution Research - Phenol is a widely used synthetic organic compound, which according to global estimations, is discharged into the environment at a rate of 10...     

Photocatalysis for arsenic removal from water: considerations for solar photocatalytic reactors

Environmental Science and Pollution Research - The following work provides a perspective on the potential application of solar heterogeneous photocatalysis, which is a nonselective advanced...     

Electrochemical monitoring of methylparathion degradation in an acid aqueous medium in presence of Cu(II)

A study was undertaken to determine the effect of Cu(II) in degradation of methylparathion (o,o-dimethyl o,4-nitrophenyl phosphoriotioate) in acid medium. Initial electrochemical characterization of Cu(II) and methylparathion was done in an aqueous medium at a pH range of 2-7. Cu(II) was studied in the presence of different anions and it was observed that its electroactivity depends on pH and is independent of the anion used. Methylparathion had two reduction signals at pH < or = 6 and only one at pH > 6. The pesticide's transformation kinetic was then studied in the presence of Cu(II) in acid buffered aqueous medium at pH values of 2, 4, and 7. Paranitrophenol appeared as the only electroactive product at all three pH values. The reaction was first order and had k values of 5.2 x 10(-3) s(-1) at pH 2, 5.5 x 10(-3) s(-1) at pH 4 and 9.0 x 10(-3) s(-1) at pH 7. It is concluded that the principal degradation pathway of methylparathion in acid medium is a Cu(II) catalyzed hydrolysis reaction.     

Evaluation of relative photonic efficiency in heterogeneous photocatalytic reactors

The evaluation of photonic efficiency in heterogeneous photocatalysis remains elusive because the number of absorbed photons is difficult to assess experimentally. The photonic efficiency of heterogeneous photocatalytic reactors depends on the reactor geometry, irradiation source, and photocatalyst properties. In this work, the relative photonic efficiency of heterogeneous photocatalytic reactors to degrade an azo dye was evaluated using phenol as the standard system. The experimental tests were carried out in a batch reactor under different conditions of pH, catalyst dosage, initial concentration, and ultraviolet (UV) lamps. The kinetics of disappearance of both phenol and azo dye were studied using the initial rate method and were described according to the Langmuir-Hinshelwood (L-H) kinetic model. It was observed that the relative photonic efficiency depends on the adsorption/desorption properties of the photocatalyst.     

DOC removal paradigms in highly humic aquatic ecosystems

Background, aim, and scope  Dissolved humic substances (HS) usually comprise 50–80% of the dissolved organic carbon (DOC) in aquatic ecosystems. From a trophic and biogeochemical perspective, HS has been considered to be highly refractory and is supposed to accumulate in the water. The upsurge of the microbial loop paradigm and the studies on HS photo-degradation into labile DOC gave rise to the belief that microbial processing of DOC should sustain aquatic food webs in humic waters. However, this has not been extensively supported by the literature, since most HS and their photo-products are often oxidized by microbes through respiration in most nutrient-poor humic waters. Here, we review basic concepts, classical studies, and recent data on bacterial and photo-degradation of DOC, comparing the rates of these processes in highly humic ecosystems and other aquatic ecosystems. Materials and methods  We based our review on classical and recent findings from the fields of biogeochemistry and microbial ecology, highlighting some odd results from highly humic Brazilian tropical lagoons, which can reach up to 160 mg C L⁻¹. Results and discussion  Highly humic tropical lagoons showed proportionally lower bacterial production rates and higher bacterial respiration rates (i.e., lower bacterial growth efficiency) than other lakes. Zooplankton showed similar δ¹³C to microalgae but not to humic DOC in these highly humic lagoons. Thus, the data reviewed here do not support the microbial loop as an efficient matter transfer pathway in highly humic ecosystems, where it is supposed to play its major role. In addition, we found that some tropical humic ecosystems presented the highest potential DOC photo-chemical mineralization (PM) rates reported in the literature, exceeding up to threefold the rates reported for temperate humic ecosystems. We propose that these atypically high PM rates are the result of a joint effect of the seasonal dynamics of allochthonous humic DOC input to these ecosystems and the high sunlight incidence throughout the year. The sunlight action on DOC is positive to microbial consumption in these highly humic lagoons, but little support is given to the enhancement of bacterial growth efficiency, since the labile photo-chemical products are mostly respired by microbes in the nutrient-poor humic waters. Conclusions  HS may be an important source of energy for aquatic bacteria in humic waters, but it is probably not as important as a substrate to bacterial growth and to aquatic food webs, since HS consumption is mostly channeled through microbial respiration. This especially seems to be the case of humic-rich, nutrient-poor ecosystems, where the microbial loop was supposed to play its major role. Highly humic ecosystems also present the highest PM rates reported in the literature. Finally, light and bacteria can cooperate in order to enhance total carbon degradation in highly humic aquatic ecosystems but with limited effects on aquatic food webs. Recommendations and perspectives  More detailed studies using C- and N-stable isotope techniques and modeling approaches are needed to better understand the actual importance of HS to carbon cycling in highly humic waters.