Lead (Pb) persists among the most hazardous contaminant metals. Pb-induced genotoxic effects remain a matter of debate as they are a major cause of plant growth impairment, but assessing Pb genotoxicity requires the selection of Pb-sensitive genotoxic biomarkers. Seedlings of the ecotoxicological model species Pisum sativum L. were exposed to Pb²⁺ (≤ 2000 mg L⁻¹). Flow cytometry (FCM) revealed that 28 days after, Pb²⁺ arrested root cell cycle at G₂ but no eu/aneuploidies were found. Comet assay and FCM-clastogenicity assays showed that Pb²⁺ increased DNA breaks in roots at concentrations as low as 20 mg L⁻¹. Leaves showed no variation in DNA-ploidy or cell cycle progression but had increased DNA breaks at the highest Pb²⁺ dose. We conclude that both Comet assay and the full-peak coefficient of variation (FPCV) were the most relevant endpoints of Pb-phytogenotoxicity. Also, the Pb-induced DNA breaks may be related with the arrest at the G₂-checkpoint. Data will be relevant to better define Pb²⁺ ecogenotoxicological effects and their measuring tools and may contribute to a regulatory debate of this pollutant limits.

As geographic limitation has gradually vanished, many economic activities occurred with apparent spillover on the neighboring regions. To study other social pressures on energy consumption considering spatial spillover effects, this paper constructs STIRPAT spatial model to investigate the relationship among energy intensity, foreign direct investment (FDI), economic growth, population scale, and technology progress in the case of 30 provinces in China over the period of 2001–2016. Spatial correlation test methodologies are applied, and STIRPAT spatial Durbin model (SDM) is preferred to describe the pushing-in and pushing-out effects among regions. We find that there is obvious spatial spillover of energy intensity; economic growth, industrial development, and population scale positively relate to energy intensity in local regions; technology progress is an effective way for energy conservation; the spillover effects of global domestic production (GDP), population size, and technology in adjacent regions are significant on local energy consumption; in China, FDI inflows into the local and neighboring regions negatively affect energy intensity, indicating that FDI would release the pressure of energy consumption.

Copper (Cu) is one of the micronutrients needed by living organisms. In plants, Cu plays key roles in chlorophyll formation, photosynthesis, respiratory electron transport chains, oxidative stress protection as well as protein, carbohydrate, and cell wall metabolism. Therefore, deficiency of Cu can alter various functions of plant metabolism. However, Cu-based agrochemicals have traditionally been used in agriculture and being excessively released into the environment by anthropogenic activities. Continuous and extensive release of Cu is an imperative issue with various documented cases of phytotoxicity by the overproduction of reactive oxygen species (ROS) and damage to carbohydrates, lipids, proteins, and DNA. The mobility of Cu from soil to plant tissues has several concerns including its adverse effects on humans. In this review, we have described about importance and occurrence of Cu in environment, Cu homeostasis and toxicity in plants as well as remediation and progress in research so far done worldwide in the light of previous findings. Furthermore, present review provides a comprehensive ecological risk assessment on Cu in soils and thus provides insights for agricultural soil management and protection.

Polycyclic aromatic hydrocarbons as byproducts of carbon-based fuel combustion are an important group of pollutants with wide distribution in the environment. Polycyclic aromatic hydrocarbons are known as toxic compounds for almost all organisms. Different plant species can uptake polycyclic aromatic hydrocarbons by roots and translocate them to various aerial parts. The aim of this study is to investigate the uptake, translocation, and accumulation of pyrene and phenanthrene in maize under controlled conditions. Seeds were cultivated in perlite containing 25, 50, 75, and 100 ppm of phenanthrene and pyrene, and their concentrations in the roots and shoots of the plants were measured using high-performance liquid chromatography technique after 7, 14, and 21 days. The results revealed that phenanthrene naturally existed in maize and its concentration showed a time-dependent decrease in shoots and roots. In contrast, the concentration of pyrene was increased in the roots and reduced in the shoots. Although pyrene had higher uptake than phenanthrene in roots of maize, the translocation factor value for pyrene was lower than for phenanthrene. According to these findings, phenanthrene could be metabolized in maize in the shoot and root tissues, but pyrene had more tendency to be accumulated in roots.

A laboratory-scale study was conducted to investigate the effect of bioaugmentation (BA) and biostimulation (BS) on the remediation of oily sludge with high total petroleum hydrocarbon (TPH) content (269,000 mg/kg d.w. sludge). TPH concentration significantly decreased by 30.4% (P < 0.05) in the BS treatment after 13-week incubation, and 17.0 and 9.1% of TPH was removed in the BA and control treatments (amended with sterile water only), respectively. Aliphatic and other fractions (i.e., saturated n-alkanes and cyclic saturated alkanes) were reduced in the BS treatment, whereas no decrease in aromatic hydrocarbons occurred in any treatment. Gas chromatography–mass spectrometry analysis of aliphatic fractions showed that low-chain-length alkanes (C8–C20) were the most biodegradable fractions. The BS treatment supported fungal proliferation, with Sordariomycetes and Eurotiomycetes as the dominant classes. BS increased fungal diversity and decreased fungal abundance, and changed bacterial community structure. The findings show the potential of using BS to treat oily sludge with high TPH content. Graphical abstract

Drawing on the insights from the literature in environmental economics and politics, this study examines the configurational conditions of national carbon intensity by constructing a new analytical framework integrating six factors, i.e. population, affluence, industrial structure, energy intensity, urbanization rate and democracy. A fuzzy set analysis of 136 countries shows that national carbon intensity is not determined by any single factor but rather by the combined effects of multiple factors. There are two configurational pathways to low-carbon development while four pathways to high-carbon development, each with its own configuration. Low-carbon development occurs most often in those affluent, highly urbanized and democratic countries with low intensity of energy use, while high-carbon development is most likely in those small, poor countries with high intensity of energy use. This study also shows that the role of particular factor should be understood in the context as its combinations with different sets of other factors may produce opposite effects on national carbon intensity. That is, the policy efforts concentrated on single factor may be ineffective to reduce carbon intensity. These findings permit a more contextualized and systematic understanding of the determinants of national carbon intensity.

The impact of Moringa oleifera leaf ethanol extract (MOLEE) was assessed on the expression of the steroidogenic genes (steroidogenic acute regulatory protein (StAR) and cytochrome P450c17 subfamily a (CYP17a) and luteinizing hormone receptor (LHR) gene) as well as on the cadmium chloride (CdCl₂)–induced reproductive toxicity for 56 days in male rats. Four groups were used: control, Moringa-treated (MOLEE), CdCl₂-treated, and CdCl₂ + MOLEE groups. The reproductive toxicity of CdCl₂ was confirmed; it caused a significant decrease in the accessory sex organ weights, testosterone level, testicular GST level, elevated MDA level (lipid peroxidation indicator), and histopathological alterations in seminiferous tubules, prostate, seminal vesicles, and epididymis as well as sperm characteristics. It also induced downregulation in the expression of StAR and CYP17a genes without change in the expression LHR gene. Eleven active compounds were detected in the GC-MS analysis of MOLEE; six of them have antioxidant properties, and five new compounds presented variable activities. MOLEE alone induced a stimulatory effect on the expression of steroidogenic and LHR genes. It restored the weight of reproductive organs to the control level; however, the recovery in sperm count, motility, abnormalities, percentage of alive sperm, testosterone, and MDA level are still comparable with the control level. Similar findings were also reported at the histological structure of the testes, epididymis, and accessory sex glands. Complete recovery of the GST enzyme activity was observed. Additionally, a restoration in the expression level of the steroidogenic genes was also reported. Our results indicated that the concurrent administration of MOLEE with CdCl₂ can partially mitigate its harmful effects on male fertility.

The current study demonstrates oxidative damage and associated neurotoxicity following pH stress in two freshwater carp Labeo rohita and Cirrhinus cirrhosus. Carp (n = 6, 3 replicates) were exposed to four different pH (5.5, 6, 7.5, and 8) against control (pH 6.8 ± 0.05) for 7 days. After completion of treatment, levels of enzymatic (superoxide dismutase [SOD], catalase [CAT], glutathione reductase [GRd]) and non-enzymatic antioxidants (malondialdehyde [MDA], glutathione [GSH]), brain neurological parameters (Na⁺-K⁺ATPase, acetylcholinesterase [AcHE], monoamine oxidase [MAO], and nitric oxide [NO]), xanthine oxidase (XO), heat shock proteins (HSP70 and HSP90), and transcription factor NFkB were measured in carp brain. Variation in the pH caused a significant alteration in the glutathione system (glutathione and glutathione reductase), SOD-CAT system, and stress marker malondialdehyde (MDA). Xanthine oxidase was also induced significantly after pH exposure. Brain neurological parameters (MAO, NO, AChE, and Na⁺-K⁺ATPase) were significantly reduced at each pH-treated carp group though inhibition was highest at lower acidic pH (5.5). Cirrhinus cirrhosus was more affected than that of Labeo rohita. Molecular chaperon HSP70 expression was induced in all pH-treated groups though such induction was more in acid-stressed fish. HSP90 was found to increase only in acid-stressed carp brain. Expression of NFkB was elevated significantly at each treatment group except for pH 7.5. Finally, both acidic and alkaline pH in the aquatic system was found to disturb oxidative balance in carp brain which ultimately affects the neurological activity in carp. However, acidic environment in the aquatic system was more detrimental than the alkaline system regarding oxidative damage and subsequent neurotoxicity in carp brain.

Persistent organic pollutants (POPs) constitute a wide range of chemicals. Their release into the environment has raised great concern due to their potentially harmful impact in humans and wildlife species. The aim of this current study was to detect selected POPs in hair samples of wild terrestrial mammals from Primorsky Krai, Russia, so as to assess potential environmental exposure. The tested wild species were leopard cat, musk deer, wolf, amur hedgehog, and raccoon dog. The targeted organochlorines were hexachlorobenzene (HCB) and DDTs (opDDE, ppDDE, and opDDD), polychlorinated biphenyl (PCB) congeners (28, 52, 101, 118, 138, 153, and 180), and polycyclic aromatic hydrocarbons (PAHs) (acenaphylene (ACEN), fluorene (FLU), anthracene (ANTH) phenathrene (PHEN), and pyrene (PYR)). The detection of POPs was conducted in hair samples by a one-step hair extraction method, by using a headspace solid-phase microextraction technique (HS-SPME) and analyzed then by GC-MS. The majority of the wild animal hair samples were found positive in all tested pollutants. More specifically, the percentage of positive hair samples for HCB was 93.3% and for DDTs, PCBs, and PAHs, 20.0 to 100.0%, 6.7 to 100.0%, and 75.0 to 100.0%, respectively. DDT, PCB, and PAH detection ranged from 1.26 to 52.06 pg mg⁻¹, 0.73 to 31.34 pg mg⁻¹, and 2.59 to 35.00 pg mg⁻¹, respectively. The highest mean concentration levels of all tested pollutants were found for musk deer (PCBs 12.41 pg mg⁻¹, DDTs 21.87 pg mg⁻¹, PAHs 22.12 pg mg⁻¹) compared to the other wild species. To the best of our knowledge, this is the first study that provides results regarding contamination in different terrestrial mammals by POP exposure. The use of hair as a matrix is proven to be an effective tool for nondestructive biological monitoring of POP contamination in terrestrial ecosystems.

To study the impact of leachate recirculation frequency on the transformation of carbon and nitrogen pollutants in a semi-aerobic bioreactor landfill (SABL), three laboratory-scale SABLs were investigated, each using a different leachate recirculation frequency (daily, once each 3 days, and once each 5 days). Results showed that degradation of total nitrogen (TN), ammonium nitrogen (NH₄⁺-N), chemical oxygen demand (COD), and total organic carbon (TOC) could be described using a quadratic polynomial-compound index model. Degradation rates of TN, NH₄⁺-N, COD, and TOC slightly increased from 0.01795, 0.01814, 0.01451, and 0.01166 day⁻¹ to 0.02054, 0.01903, 0.01488, and 0.01203 day⁻¹, respectively, when the recirculation frequency increased from once per 5 days to once per 3 days. When recirculation frequency was increased to daily, degradation rates of TN, NH₄⁺-N, COD, and TOC significantly increased to 0.03698, 0.02718, 0.02479, and 0.02872 day⁻¹, respectively. Moreover, when recirculation frequency increased from once per 5 days to once per 3 days, the gasification rate of nitrogenous and carbonaceous pollutants was enhanced between 20.38 and 8.17%, respectively. When the leachate recirculation rate further increased to daily, only a small amount of carbonaceous and nitrogenous pollutants was transformed to the liquid phase. Thus, increasing the leachate recirculation frequency in an SABL benefits the removal of carbonaceous and nitrogenous pollutants from the reactor. In addition, the greater is the recirculation frequency, the lower is the residual carbon and nitrogen in the solid phase, and the higher is the gasification rate. A proper recirculation frequency promotes the stabilization of landfill leachate. This study provides a theoretical reference and experimental evidence for accelerating the stabilization of MSW and contributes to the macro-control of landfills.