Industrial activities such as leather tanning involve the use of highly toxic inorganic pollutants, like Chromium (Cr). This work evaluated Cr(VI) remediation by hairy roots (HR) of Brassica napus, paying close attention to the mechanisms involved and the toxicity of post-removal solutions. Results showed that these roots were capable of tolerating concentrations of up to 10 mg L⁻¹ Cr(VI), while higher concentrations were toxic for HR development. Removal efficiency was assessed through the use of synthetic solutions containing different initial Cr(VI) concentrations (2, 5, or 10 mg L⁻¹). Regardless of these initial concentrations, the highest removal efficiency values were between 80 and 90% after 24 and 48 h of treatment, using a 2.0 g inoculum. The mechanisms involved were Cr accumulation (60%) and to a lesser extent, adsorption to the root biomass (30%). A fraction of Cr(VI) was intracellularly reduced to Cr(III), which suggests reductases may have played a role. Additionally, post-removal toxicity was evaluated through two bioassays (Lactuca sativa L. and AMPHITOX test) after the removal of 10 mg L⁻¹ Cr(VI). The treated solutions showed moderate phytotoxicity for L. sativa L. and no toxicity for R arenarum. The ability of HR to remove 10 mg L⁻¹ Cr(VI) from real tannery effluents collected from a regional industry (Córdoba province, Argentina) was also determined. The high removal efficiency observed (98%) demonstrates this system can be successful in treating complex wastewaters.

Dioctyl phthalate (DOP) (200, 500, and 1000 mg kg⁻¹ bw, i.g.), Pb (Ac)₂ (50 mg L⁻¹, p.o.), and NaAsO₂ (10 mg L⁻¹, p.o.) were administered individually and as mixtures to weanling male mice for 8 weeks. It was observed that Pb, As, and DOP exposure could significantly inhibit the growth and development of mice. Compared with the Pb, As, and Pb + As groups, the activities of iNOS and TNOS were significantly increased, the levels of AChE and SOD were significantly decreased, and the level of MDA was significantly increased in the Pb + DOP-H, As + DOP-H, and Pb + As + DOP-H groups. The factorial analysis shows that the iNOS, TNOS, and AChE present synergistic effects on Pb, As, and DOP. A significant increase of escape latency and a significant decrease of original platform quadrant stops were observed between Pb + As + DOP-H and Pb + As groups. The factorial analysis shows that there was a synergistic effect on Pb, As, and DOP. Compared with that of the control group, the expression levels of caspase-3 and Bax expression in Pb + As, DOP-H, Pb + DOP-H, As + DOP-H, and Pb + As + DOP-H groups were significantly increased in the hippocampus. The expression levels of Bcl-2 expression decreased significantly and the Bax/Bcl-2 ratio increased significantly. Pathological alterations on the hippocampus were found in exposed groups. This result shows that combined exposure of Pb, As, and DOP could induce neurotoxicity, of which possible mechanism is hippocampal neuronal apoptosis. Graphical abstract This study shows that there were three components with eigenvalues greater than 1, which together explained 89.40% of total variance. The first component (PC1) showed high loadings on B-SOD, L-SOD, B-MDA, L-MDA, K-MDA, iNOS, tNOS, and AChE and accounted for 46.55% of the total variance after Varimax rotation. PC2 accounted for 23.81% of the total variance with high loadings on B-As, L-As, K-As, and K-SOD, whereas PC3 showed high loadings on B-Pb, L-Pb, and K-Pb and accounted for 19.04% of the total variance.

The freshwater mollusk, Melanoides tuberculata, contains bioconcentration trace metals in its tissues from the surrounding area. M. tuberculata was used as a bioindicator for pollution with seven trace metals (Mn, Fe, Ni, Cu, Zn, Cd, and Pb) accumulated in snail soft tissues near Bahr El-Baqar and El-Serw agricultural drains of industrial activities in Port Said and Damietta, respectively. The biota sediment accumulation factors (BSAF) in this study reveals that all the soft tissues of the M. tuberculata snails were macro-concentrators with the exception of Ni; it was deconcentrated, and thus provides that the selective tissues as good biomonitors. The bioconcentration factor (BCF) showed the highest concentrations of Fe and Cu in the soft tissues of the M. tuberculata snail, which has the potential to be used as a biomonitoring agent for Fe and Cu contamination of the water.

In modern agriculture, farm produce accumulates a lot of nitrates that can reach toxic levels owing to the unfair use of nitrogen fertilizers, cultural methods, farming policies in multiple areas of the world, thereby increasing concerns about the availability of hygienic food supply and environmental hazards. Over the past few decades, global interest in achieving greater output through intensive fertilization has been a growing trend. The fertilizer based on urea or ammonium mainly yields ammonium, which is then transformed to nitrate through the oxidation process that is biologically mediated. Nitrate tends to accumulate differently in distinct crop plants and distinct components of agricultural commodities based on species, crop variety, genetic history, environmental circumstances, harvest phase, post-harvest storage conditions, agronomic variables, nature, and fertilizer application rate. The current article highlights various factors that could directly or indirectly contribute to the accumulation of nitrates in different parts of crop plants and discusses strategies to minimize the accumulation of nitrates in farm produce, thus ensuring healthy food supply and protecting the environment from the accumulation of nitrates.

Embracing energy efficiency (EE) and renewable energy (RE) is essential for improving environmental quality. This research investigates the asymmetric impacts of EE, RE, and other factors on CO₂ emissions in BRICS (i.e., Brazil, Russia, India, China, and South Africa) countries from 1990 to 2014. In contrast to previous studies, the present study considers EE as a major cause of CO₂ emissions in BRICS countries. By using the new hidden panel cointegration and nonlinear panel autoregressive distributive lag model, this study is the first of its kind that unfolds the asymmetric links among EE, RE, and CO₂ emissions. Findings clearly explain that the impact of the selected variables on CO₂ emissions is asymmetric, and both EE and RE help to lower CO₂ emissions in BRICS countries. In the long run, positive shocks in EE and RE can significantly mitigate CO₂ emissions in BRICS economies. In particular, a 1% fluctuation in the positive sum of EE reduces CO₂ emissions by 0.783% in the long run. On the other hand, a 1% fluctuation in the positive component of RE reduces CO₂ emissions by 0.733%. Moreover, individual country estimates suggest the heterogeneous effects among BRICS countries. Based on the empirical findings, policymakers should consider the asymmetric behavior of the EE, RE, and economic growth while formulating, energy, environment, and growth policies of BRICS countries. Graphical abstract

Applying the climatological water balance (WB) concept to describe the relationship between climatic seasonality and surface water quality according to different forms of land use and land cover (LULC) is an important issue, but little explored in the literature. In this paper, we evaluate the influence of WB on surface water quality and its impacts when interacting with LULC. We monitored 11 sampling points during the four seasons of the year, from which we estimate WQI (water quality index) and TSI (trophic state index). We found an effect of the seasonality factor on both WQI values (F(3,30) = 12.472; p < 0.01) and in TSI values (F(3,30) = 6.967; p < 0.01). We noticed that LULC interferes in the way that the water balance influences the WQI and TSI values since in sampling points closest to higher urban density, with little or no riparian protection, the correlation between water balance and water quality was lower. In the stations that had the lowest water surplus and deficit, there was positive linearity between water balance and WQI. However, in the seasons when the surplus and water deficit recorded were extreme, there was no linearity. We conclude that water deficiency impairs the quality of surface water. In the extreme surplus water season, the homogeneity of WQI samples was lower, suggesting a higher interaction between rainwater and LULC. This study contributes to design management strategies of water resources, considering the climatic seasonality for optimization.

This paper investigates the nexus between carbon emissions (CO₂) and economic growth in West Africa based on the Environment Kuznets Curve (EKC) hypothesis by utilizing spatial panel data technique to check the possible effect of spatial dependence among countries in West Africa. Our empirical findings suggest the presence of spatial dependence of carbon emissions distribution in West Africa. By examining the existence of EKC embedded within the Stochastic Impacts by Regression on Population, Affluence, and Technology (STIRPAT) approach, we conclude an inverse N-trajectory of the relationship between carbon emissions and economic growth. Furthermore, to mitigate global carbon emissions, we utilize a recurrent neural network (RNN) bidirectional long short-term memory (BiLSTM) algorithm devoid of exogenous variables and assumptions to forecast carbon emissions from the year 2015 to the year 2030 based on the predictive accuracy of our formulated algorithm. Due to the upward trends in future emission levels, we propose emissions mitigation pathways for countries in West Africa to still hold carbon emissions-related global warming well below 1.5 and 2 °C. Such mitigation pathways proposed could help implement strategic policies to minimize carbon emissions to a considerable level. As a policy implication, drafting strict environmental regulations and utilizing renewable energy technologies will help mitigate carbon emissions for all West African countries.

This study analyzes the impact of economic growth, energy consumption, trade openness, and tourism on environmental degradation measured by CO₂ emissions by using annual data of 112 countries for the period 1995 to 2017. Furthermore, the study also analyzes the relationship of the variables as mentioned above in four income and five regional groups of the world. The findings confirm the existence of environmental Kuznets curve (EKC), and level of income (turning point) is also determined, which helps in the improvement of the environmental quality of selected sample countries. The results of the overall sample show that economic growth, use of energy, and tourism are proved to be harmful to the environment, whereas the result of trade openness is not statistically robust. Results of sub-samples are mixed. Findings of this study highlight some essential steps which must be taken by the government and international environmental agencies for the protection of the environment through efficient utilization of energy and sustainable tourism.

Understanding the relationship between nitrogen (N) cycle and N transformation-related functional genes is crucial to reduce N loss during composting process. Urease inhibitor (UI) is widely used to reduce N loss in agriculture. However, the effects of UI on N transformation and related N functional genes during composting have not been well investigated. The goal of this study was to investigate the effects of a urease inhibitor (UI) on N functional genes and bacterial community succession during pig manure composting. Results showed that the addition of UI decreased the ammonium N content during the thermophilic stage and notably increased the total N and nitrite N contents of the final compost. The UI significantly decreased the abundances of amoA, nirS, nirK, and nosZ during the initial composting stage, while the opposite trend was observed at the maturation stage. Bacterial community richness and diversity were increased after the UI amendment, but the relative abundance of the phyla Firmicutes and Proteobacteria significantly decreased compared with control during the thermophilic stage. Redundancy analysis indicated that the evaluated environmental factors and bacterial community showed a cumulative 94.7% contribution to the total variation in N functional genes. In summary, UI addition is a recommended method for N conservation during composting, but the added forms of UI, such as delayed addition, combined with adsorbing materials, or microorganism inoculant, should be further evaluated.