Sunflower stalk–derived biochars (BC) were prepared at various temperatures (i.e., 500, 650, and 1000 °C) and demonstrated as a highly efficient catalyst in persulfate (PS) activation for the oxidation of p-nitrophenol (PNP) at 60 °C. The apparent PNP oxidation rate constant in the BC500 (0.1543 L mol⁻¹ S⁻¹), BC650 (0.6062 L mol⁻¹ S⁻¹), or BC1000 (2.1379 L mol⁻¹ S⁻¹) containing PS system was about 2, 8 and 28 times higher than that in PS/PNP (0.0751 L mol⁻¹ S⁻¹) system, respectively. The effect of reaction temperature on PNP oxidation was also investigated. Furthermore, the radical quenching tests and electron paramagnetic resonance spectroscopy (EPR) were employed to investigate the sulfate and hydroxyl radicals for PNP oxidation. The Raman results suggested that the defective sites on biochars possess vital role for oxidation of PNP in PS system. The possible activation pathway of PS/BC was proposed that the defective sites on BC were involved for weakening the O–O bond in PS and subsequently cleaving O–O bond by heat to generate sulfate radical. The oxidation of PNP at low concentration (below 100 μg L⁻¹) was completely removed in urban wastewater by PS/BC system within 30 min. This work would provide new insights into PS activation by BC catalyst and afford a promising method for organic pollutant removal in high-temperature wastewater.

Tibial dyschondroplasia (TD) is most the common tibiotarsal bone disease in rapidly growing birds throughout the world. There is accumulating evidence that COX-2 abnormal expression in tibia plays an important role in TD progression. So, the regulation of COX-2 is an ever more appealing target for therapeutic intervention in TD. Astragaloside IV has an indispensable role in maintaining COX-2 expression in many diseases. So, we designed this study to use Astragaloside IV (AST-IV) against TD-affected chickens. A total of 180 Arbor Acres chickens were randomly divided in the control group, TD group, and Astr (AST-IV-treated chickens) group. During the experiment, mortality, feed conversion ratio, physiological changes, biochemical criterion, liver antioxidant enzymes, and gene expression of COX-2 were examined in all the chicken groups at various days. The results showed that AST-IV administration restored the growth performance and tibia lesions and decreased the mortality as compared with TD chickens. The biochemical criterion (ALP, AST, and ALT) of serum and liver antioxidant enzymes (SOD, GSH-Px, MDA, and T-AOC) improved after the administration of AST-IV. The COX-2 gene was upregulated significantly (P < 0.05) in TD chickens. Whereas, AST-IV treatment downregulated both gene and protein expression of COX-2 significantly (P < 0.05) in TD-affected chickens. AST-IV recovered tibial dyschondroplasia chickens by increasing the growth performance, ameliorating tibial cartilage damage, and decreasing COX-2 expression. In conclusion, AST-IV can be used to prevent thiram-induced TD in chickens.

Stable Hg(II)-containing flue gas has been successfully simulated by the plasma oxidation of Hg(0), and an effective solution for Hg(0) mercury fumes was obtained by combining the plasma with a ceramic nanomaterial. Characterization tests showed that the ceramic nanomaterial was mainly composed of silicon dioxide (SiO₂) with other minor constituents, including potassium mica (KAl₃Si₃O₁₁), iron magnesium silicate (Fe₀.₂₄Mg₀.₇₆SiO₃) and dolomite (CaMg(CO₃)₂). The nanomaterial had many tube bank structures inside with diameters of approximately 8–10 nm. The maximum sorption capacity of Hg(II) was 5156 μg/g, and the nanomaterial can be regenerated at least five times. During the adsorption, chemical adsorption first occurred between Hg(II) and sulfydryl moieties, but these were quickly exhausted, and Hg(II) was then removed by surface complexation and wrapped into Fe moieties. The pseudo-first-order kinetic model and the Langmuir equation had the best fitting results for the kinetics and isotherms of adsorption. This work suggests that the ceramic nanomaterial can be used as an effective and recyclable adsorbent in the removal of gaseous Hg(II).

The denitrifying anaerobic methane oxidation (DAMO) process can achieve methane oxidation and denitrification at the same time by using nitrate or nitrite as an electron acceptor. The short- and long-term effects of nitrite on DAMO organisms were studied from macro (such as denitrification) to micro (such as microbial structure and community) based on two types of DAMO microbial systems. The results showed that the inhibitory effects of nitrite on the two DAMO microbial systems increased with rising concentration and prolonged time. In the short-term inhibitory phase, nitrite with concentrations below 100 mg N L⁻¹ did not inhibit the two distinct DAMO enrichments. When nitrite concentration was increased to 950 mg N L⁻¹, the nitrogen removal performance was completely inhibited. However, in the long-term inhibition experiment, when nitrite concentration was increased to 650 mg N L⁻¹, the nitrogen removal performance was completely inhibited. In addition, in acidic conditions, the real inhibitor of nitrite is FNA (free nitrous acid), while in alkaline conditions, the real inhibitor is the ionized form of nitrite. By using high-throughput sequencing technology, the species abundance and diversity of the two DAMO microbial systems showed an apparent decrease after long-term inhibition, and the community structure also changed significantly. For the enrichment culture dominated by DAMO bacteria, the substantial drop of Methylomonas may be the internal cause of the decreased nitrogen removal rate, and for the coexistence system that hosted both DAMO bacteria and archaea, the reduction of Nitrospirae may be an internal reason for the decline of the denitrification rate.

In this paper, we present a characterization of the optical properties of the aerosols emitted during biomass burning (BB) season in the period 2005–2009. Trends of aerosol optical depth (AOD), Angstrom exponent (α), and precipitable water (PW) were analyzed using a 5-year dataset from AErosol RObotic NETwork (AERONET) observations over Tuxtla Gutierrez (TG), Chiapas. The overall mean AOD (500 nm) during the 2005–2009 period was 0.26 ± 0.18. However, monthly mean values of AOD > 0.5 during the spring months (April and May) would indicate the high load of particles emitted by fires. The overall mean of α (440–870 nm) was 1.40 ± 0.21, which confirms the presence of fine aerosols. Additionally, the combined analysis of the α with its spectral curvature δα, and the results from the spectral de-convolution algorithm (SDA) shows that fine-mode aerosols dominated AOD variability in TG. In this paper, the trajectories of air masses (400 and 1500 m, a.s.l.) arriving at the TG site were classified by using backward trajectory cluster analysis. Trajectory clustering results indicate a BB regional transport from Central America that affects the atmosphere in southeastern Mexico. We use observations of fire radiative power (FRP) from the Moderate Resolution Imaging Spectroradiometer (MODIS) to study the incidence of wildfires and to estimate the BB emissions from 2005 to 2009 in southeastern Mexico. The results indicated a gradual decrease in fires throughout the years. Campeche and Yucatan are the states in southeastern Mexico where BB produces the highest emissions of carbon dioxide (CO₂), carbon monoxide (CO), black carbon (BC), and particulate material PM₂.₅. However, the largest emissions come from wildfires in Guatemala. Finally, to put in context the aerosol optical properties over southeastern Mexico, the sun photometric measurements in TG are compared with those retrieved from AERONET stations located in other tropical biomass burning regions (Brazil and Zambia).

Agriculture intensification and the use of pesticides have led to biodiversity loss due to soil toxic compounds. Thus, soil contamination studies are important to understand the negative effects in the physicochemical interactions. The use of biomarkers through bioindicators is a useful tool for assessing toxicity in agricultural environments complemented with the determination of pesticides. The objectives of this study were to determine the presence of organochlorine (OCPs) and organophosphate (OPPs) pesticides and the soil’s potential toxicity in agricultural fields with different crops from the center of Quintana Roo State, using a set of enzymatic biomarkers (BMs), such as acetylcholinesterase (AChE), glutathione-S-Transferase (GST), and catalase (CAT) on earthworms (Eisenia fetida). Earthworms were exposed for 96 h on nine different agricultural soils as well as on a reference soil from a conservation area. Within all samples of soils, only OCPs were detected in low concentrations (ranged from non-detected to 1.40 ppm). However, no correlation was observed between these pesticides and the BMs activity. AChE and CAT activity was significantly inhibited in at least one agricultural soil if compared to the conservation area, while no significant differences of GST were observed. The AChE activity observed suggests the presence of anticholinergic substances (that were neither detected nor determined analytically) in the sampled soils. The characterization of oxidative stress BMs was not correlated with the OCPs analyzed. Our results demonstrate that further studies of toxicity under field conditions are required, given the complexity of environmental conditions outside the laboratory.

Inorganic and organic constituents present in textile effluents have a noticeable effect on the performance of Fenton processes. However, studies have been focused on simple wastewater matrices that do not offer enough information to stakeholders to evaluate their real potential in large-scale facilities. Chemical auxiliaries, commonly present in textile wastewaters (NaCl = 30 g/L, Na₂CO₃ = 5 g/L, and CH₃COONa = 1 g/L), affect both the economic and environmental performance of the process because they increase the treatment time (from 0.5 to 24 h) and the consumption of H₂SO₄ (657%) and NaOH (148%) during conditioning steps. The life cycle assessment (LCA) performed with the IPCC-2013 method revealed that dyeing auxiliaries increase from 1.06 to 3.73 (252%) the emissions of carbon dioxide equivalent (CO₂-Eqv/m³). Electricity consumption can be considered an environmental hotspot because it represents 60% of the carbon footprint of the Fenton process. Also, the presence of auxiliaries is critical for the process because it results in the increase of the relative impact (between 50 and 80%) in all environmental categories considered by the ReCiPe-2008 method. Chemical auxiliaries increased the costs of the treatment process in 178% (US$2.22/m³) due to the higher energy consumption and the additional reagent requirements. It is worthwhile mentioning that the technical simplicity of the Fenton process and its low economic and environmental costs turn this process into an attractive alternative for the treatment of textile effluents in emerging economies.

Cadmium and mercury are non-biodegradable toxic metals that may cause many detrimental effects to the thyroid gland and blood. Vitamin C has been found to be a significant chain-breaking antioxidant and enzyme co-factor against metal toxicity and thus make them less available for animals. The current study was performed to find the effect of individual metals (cadmium and mercury), their co-administration, and the ameliorative effects of vitamin C on some of the parameters that indicate oxidative stress and thyroid dysfunction. Cadmium chloride (1.5 mg/kg), mercuric chloride (1.2 mg/kg), and vitamin C (150 mg/kg of body weight) were orally administered to eight treatment groups of the rabbits (1. control; 2. Vit C; 3. CdCl₂; 4. HgCl₂; 5. Vit C + CdCl₂; 6. Vit C + HgCl₂; 7. CdCl₂ + HgCl₂, and 8. Vit C + CdCl₂ + HgCl₂). After the biometric measurements of all experimental rabbits, biochemical parameters viz. triidothyronine (T₃), thyroxine (T₄), thyroid-stimulating hormone (TSH), and triglycerides were measured using commercially available kits. The results exhibited significant decline (p < 0.05) in mean hemoglobin, corpuscular hemoglobin, packed cell volume, T₃ (0.4 ± 0.0 ng/ml), and T₄ (26.3 ± 1.6 ng/ml) concentration. While, TSH (0.23 ± 0.01 nmol/l) and triglyceride (4.42 ± 0.18 nmol/l) were significantly (p < 0.05) increased but chemo-treatment with Vit C reduces the effects of Cd, Hg, and their co-administration but not regained the values similar to those of controls. This indicates that Vit C had a shielding effect on the possible metal toxicity. The Cd and Hg also found to accumulate in vital organs when measured by atomic absorption spectrophotometer. The metal concentration trend was observed as follows: kidney > liver > heart > lungs. It was concluded that Cd and Hg are toxic and tended to bioaccumulate in different organs and their toxic action can be subdued by vitamin C in biological systems.

To effectively combat global warming, an enormous reduction in CO₂ emissions is required. Cameroon, which is currently the largest emitter of CO₂ in the CEMAC subregion, has committed to reducing its greenhouse gas emissions by 32% by 2035. However, previous studies in Cameroon have only addressed the relationship between economic growth, energy consumption, and CO₂ emissions without estimating all causal relationships at the same time. Moreover, no study has yet decomposed this country’s CO₂ emissions to date. To fill these research gaps and further assess the determinants of these CO₂ emissions, an extended Kaya identity and the Logarithm Mean Divisia Index (LMDI I) have been applied in this paper to identify, quantify, and explain the main drivers of Cameroon’s CO₂ emissions from 2007 to 2014. Seven effects were measured and the main findings show that carbon intensity and the emission factor increased by 0.57% and 107.50% respectively. Regarding contributions to the increase of CO₂ emissions, the population effect was the most positive followed by the activity effect, whereas the energy intensity, the substitution of fossil fuels and the penetration of renewable energies have contributed to reduce the CO₂ emission. To enable Cameroon to not only achieve the goals of its vision but also develop a low-carbon economy, this paper provides some proposed avenues that should be considered by policymakers.

One hundred and fifty years of mineral extraction throughout the mountainous Ruby Creek watershed, Washington has left a legacy of historical hard rock mines and placer claims and their wastes. We conducted a watershed-scale chemical analysis of these gold-bearing tributaries, accounting for seasonal variability in streamflow, to identify spatial and temporal changes in stream chemistry and attribute them to natural processes or mining activities. We used hierarchical cluster analysis (HCA) to group chemically similar water samples based on concentrations of 23 metals, pH, and conductivity and compared the chemistry of HCA-generated clusters of water samples using pairwise comparisons to find chemical patterns. Total concentrations of As, Ba, Ca, Mg, Na, Sb, and Se, dissolved concentrations of Fe, and conductivity increased as streamflow progressed from snowmelt-influenced to baseflow. High total concentrations of Al, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Sb, V, and Zn during spring snowmelt and after rains were attributable to acid mine drainage at historical hard rock mines and prospect sites. Smaller-scale placer mining, by way of suction dredging and motorized gold panning, was associated with high concentrations of Al, Ba, Cd, Co, Fe, Mg, Mn, Mo, and Zn downstream. Stream biota may be adversely affected by exposure to Pb, which exceeded USEPA’s Aquatic Life Criteria, and exposure to particulate metals suspended in the water column.