The aim of this study was to evaluate changes in hematological parameters of O. niloticus exposed to sublethal concentrations of the imidacloprid in order to utilize these parameters as biomarkers of exposure. Fish with an average weight of 68.5 ± 2.0 g were exposed to sublethal concentrations of imidacloprid (1.405, 2.810, 14.050, and 28.1 mg L⁻¹) for 7 days. Blood samples were collected by puncture of the tail vein. Blood samples were used to determine the number of erythrocytes, hemoglobin level, hematocrit number, total plasma protein concentration, total and differential leukocytes count, and thrombocytes number. All tested concentrations caused changes in fish leukogram. Concentrations from 14.050 mg L⁻¹ reduced the number of erythrocytes and total plasma proteins. The tilapia exposed to 28.1 mg L⁻¹ had a significant increase in the number of thrombocytes. Although considered slightly toxic to fish, sublethal concentrations of imidacloprid in aquatic environments, even if it does not cause immediate death, may compromise the health and long-term survival of these animals. The sublethal responses adopted for evaluation toxicity in this study were sensitive and adequate to show the extent to which pesticide can affect non-target organisms. This study recommends the use of blood parameters as biomarkers of exposure of fish to pesticides.

The indirect carbon emission embodied in the intermediate input is also an important indicator of assessing a producer’s carbon emissions. Structural analysis of indirect carbon emissions is helpful to understand the responsibilities between producers and pay efforts to key areas. The aim of this study is to analyze indirect carbon emissions embodied in intermediate input between sectors and explore the distribution structure of indirect carbon emissions flow network (namely, ICEFN). Based on the modified input-output model and complex network theory, this study constructed four directed and weighted ICEFNs with 28 sectors from 1997 to 2012. The results show that indirect carbon emissions between sectors are significantly higher than direct carbon emissions, accounting for nearly 70% of the total carbon emissions of China. Second, we analyzed the embodied carbon emission intensity (namely, ECI) of each sector. Although the ECI has been decreasing over time, the decrease has increasingly diminished, which indicates that the additional carbon emission reductions are more difficult. Third, we identified the key sectors which play different roles in the ICEFNs. Meanwhile, we studied the key paths which show more closed relationships between some sectors in ICEFNs. Finally, based on the above analysis, we made policy recommendations.

Phosphogypsum (PG), the waste byproduct resulting from wet process phosphoric acid production, is employed as a selective and effective adsorbent for total rare earth elements (REEs) from aqueous solution and leach liquor. The elaboration of PG adsorbent complemented after some physical treatments. Adsorption and elution studies carried out in experimental batches, including the effect of pH, adsorbent dose, initial REE concentration, and equilibrium time. Adsorption of REEs onto PG fitted well with Langmuir isotherm with a theoretical capacity surpassed 357 mg/g. REEs were effectively eluted from loaded PG with 2 mol L⁻¹ HCl acid with an efficiency of 94%. PG showed an outstanding selectivity towards REEs in the presence of many cations and anions, for instance (Fe³⁺, UO₂²⁺, Ca²⁺, SO₄²⁻, NO₃⁻). Different qualitative techniques such as EDS, SEM, and FTIR used to emphasize the adsorption of REEs onto PG. The film diffusion model was the preponderant adsorption mechanism for REEs; also, the adsorption process has a good accordance with pseudo-second-order kinetic model.

Calcium ion-incorporated hydrous iron(III) oxide (CIHIO) samples have been prepared aiming investigation of efficiency enhancement on arsenic and fluoride adsorption of hydrous iron(III) oxide (HIO). Characterization of the optimized product with various analytical tools confirms that CIHIO is microcrystalline and mesoporous (pore width, 26.97 Å; pore diameter, 27.742 Å with pore volume 0.18 cm³ g⁻¹) material. Increase of the BET surface area (> 60%) of CIHIO (269.61 m² g⁻¹) relative to HIO (165.6 m² g⁻¹) is noticeable. CIHIO particles are estimated to be ~ 50 nm from AFM and TEM analyses. Although the pH optimized for arsenite and fluoride adsorptions are different, the efficiencies of CIHIO towards their adsorption are very good at pH 6.5 (pHzₚc). The adsorption kinetics and equilibrium data of either tested species agree well, respectively, with pseudo-second order model and Langmuir monolayer adsorption phenomenon. Langmuir capacities (mg g⁻¹at 303 K) estimated are 29.07 and 25.57, respectively, for arsenite and fluoride. The spontaneity of adsorption reactions (ΔG⁰ = − 18.02 to − 20.12 kJ mol⁻¹ for arsenite; − 0.2523 to − 3.352 kJ mol⁻¹ for fluoride) are the consequence of entropy parameter. The phosphate ion (1 mM) compared to others influenced adversely the arsenite and/or fluoride adsorption reactions. CIHIO (2.0 g L⁻¹) is capable to abstract arsenite or fluoride above 90% from their solution (0 to 5.0 mg L⁻¹). Mechanism assessment revealed that the adsorption of arsenite occurs via chelation, while of fluoride occurs with ion-exchange.

This study has compared the harvesting efficiency of four flocculation methods, namely, induced by pH, FeCl₃, AlCl₃ and chitosan. No changes were observed on M. aeruginosa cells. Flocculation assays performed at pH 3 and 4 have shown the best harvesting efficiency among the pH-induced tests, reaching values above 90% after 8 h. The adjustment of zeta potential (ZP) to values comprised between − 6.7 and − 20.7 mV enhanced significantly the settling rates using flocculant agents, being FeCl₃ the best example where increments up to 88% of harvesting efficiency were obtained. Although all the four methods tested have presented harvesting efficiencies above 91% within the first 8 h after the optimization process, the highest performance was obtained using 3.75 mg L⁻¹ of FeCl₃, which allowed reaching 92% in 4 h.

The exploitation of thallium (Tl) resources through mining poses a significant threat to ecological systems and human health due to its high toxicity and ready assimilation by human body. We report the first assessment of the pollution, spatial distribution, source, and ecological-health risks of potentially toxic elements (PTEs) in Tl mining area of southwest Guizhou, China. Spatial distribution maps for PTEs were visualized by ArcGIS to identify their distribution trends. We use the enrichment factor (EF), correlation analysis, and principal component analysis to identify likely sources of seven PTEs mining area. The wider risk assessment was evaluated using the geoaccumulation index (Igₑₒ), potential ecological risk index (RI), human non-carcinogenic risk (HI), and carcinogenic risk (CR). The results revealed the PTEs content in the study area identifies direct mining, metal production, and domestic pollution sources. In addition, the distribution of PTEs was also affected by the topography, rain water leaching, and river dispersals. The main elements of concern are Tl and As, while Cd, Cr, Cu, Pb, and Zn do not show significant enrichment in the area despite associations with the ore deposit. Risk assessment identifies strong pollution and ecological risks and poses unacceptable human health risks to local residents, especially for children. The ecological risk in the study is identified to be predominantly from Tl (74.32%), followed by As (8.57%) and Cd (7.32%). The contribution of PTEs to the non-carcinogenic risk of humans in the study area is exclusively from As and Tl, while the carcinogenic risk is dominated by As, and the other elements pose no significant risk to human health.

Cyproconazole is a triazole fungicide used to protect a diverse range of fruits, vegetables, and grain crops. As such, it has the potential to enter aquatic environments and affect non-target organisms. The objective of this study was to assess the acute toxicity of the triazole fungicide cyproconazole to zebrafish embryos by assessing mortality, developmental defects, morphological abnormality, oxidative respiration, and locomotor activity following a 96-h exposure. Zebrafish embryos at 6-h post-fertilization (hpf) were exposed to either a solvent control (0.1% DMSO, v/v), or one dose of 10, 25, 50, 100, 250, and 500 μM cyproconazole for 96 h. Data indicated that cyproconazole exhibited low toxicity to zebrafish embryos, with a 96-h LC₅₀ value of 90.6 μM (~ 26.4 mg/L). Zebrafish embryos/larvae displayed a significant decrease in spontaneous movement, hatching rate, and heartbeats/20 s with 50, 100, and 250 μM cyproconazole exposure. Malformations (i.e., pericardial edema, yolk sac edema, tail deformation, and spine deformation) were also detected in zebrafish exposed to ≥ 50 μM cyproconazole, with significant increases in cumulative deformity rate at 48, 72, and 96 hpf. In addition, a 20–30% decrease in basal and oligomycin-induced ATP respiration was observed after 24-h exposure to 500 μM cyproconazole in embryos. To determine if cyproconazole affected locomotor activity, a dark photokinesis assay was conducted in larvae following 7-day exposure to 1, 10, and 25 μM cyproconazole in two independent trials. Activity in the dark period was decreased for zebrafish exposed to 25 μM cyproconazole in the first trial, and hypoactivity was also observed in zebrafish exposed to 1 μM cyproconazole in a second trial, suggesting that cyproconazole can affect locomotor activity. These data improve understanding of the toxicity of cyproconazole in developing zebrafish and contribute to environmental risk assessments for the triazole fungicides on aquatic organisms. We report that, based on the overall endpoints assessed, cyproconazole exhibits low risk for developing fish embryos, as many effects were observed above environmentally-relevant levels.

The study explores the relationship between ecological footprint, urbanization, and energy consumption by applying the ARDL estimation technique on data spanning 1965–2014 for South Africa. After applying the unit root test that accounts for a break in the data, the Bayer and Hanck (J Time Ser Anal 34:83–95, 2013) combined cointegration test affirms cointegrating relationship among the variables. Findings further reveal that economic growth and financial development exact a deteriorating impact on the environment in the short run. However, the same was not true for both energy use and urbanization. While urbanization and energy use promote environmental quality in the long run, financial development and economic growth degrade it further. The long-run findings of our study are confirmed to be robust as reported by the fully modified OLS (FMOLS), dynamic OLS (DOLS), and the canonical cointegrating regression (CCR) estimates. The direction of causality supports the energy-led growth hypothesis for South Africa. Policy outcomes and directions, and the possibility of promoting sustainable growth without degrading the environment are discussed.

The present work aimed to evaluate the effects of commercial fungicides containing the active compounds from the triazole group—tebuconazole (TBZ) and difenoconazole (DFZ)—and dicarboximide group—procymidone (PRD) and iprodione (IPD) on the mitotic cycle of the plant model Lactuca sativa L. These active compounds have been present in foods sampled at different Brazilian’s states and amounted higher than recommended by law. The bioassay with L. sativa was applied to access the toxicity and better understand the mechanisms of action of these compounds in living beings. The active principles IPD and DFZ presented mitodepressive effect, statistically reducing the MI at all applied concentrations in comparison to the negative control. TBZ was the most cytotoxic active compound tested inhibited in 77% mitotic active in the lowest concentration applied. PRD alter the frequency of mitotic cells only in the concentration above that recommended by the manufacture. C-metaphase and adherent chromosomes were the most frequent cell cycle alteration observed on the treated cells, followed by bridges and lost chromosomes. Therefore, the mechanism of action was mainly aneugenic (70%). For TBZ, the frequency of condensed nucleus was very expressive (313 higher than the negative control).

Pistia stratiotes is a common aquatic plant of the northern region of the state of Rio de Janeiro, and its use as adsorbent material was studied in the present work. The preparation process included washing, drying, grinding, and acid activation. The sorption potential for removal of the indigo carmine dye from aqueous solutions was tested under various conditions, such as initial concentration, contact time, and temperature. The tests showed that the obtained biosorbent showed good performance for dye removal with a maximum capacity of 41.2 mg/g. The kinetic studies revealed that the pseudo-second-order equation provided the best fit of the experimental data. The Freundlich isotherm provided the best fit of the experimental sorption data for the system under study. The results obtained show that Pistia stratiotes has great potential to be used as biosorbent for the removal of dyes from aqueous solutions.