Lockdown measures to contain COVID-19 pandemic has resulted in a considerable change in air pollution worldwide. We estimate the temporal and diurnal changes of the six criteria air pollutants, including particulate matter (PM₂.₅ and PM₁₀) and gaseous pollutants (NO₂, O₃, CO, and SO₂) during lockdown (25ᵗʰ March – 3ʳᵈ May 2020) across regions of India using the observations from 134 real-time monitoring sites of Central Pollution Control Board (CPCB). Significant reduction in PM₂.₅, PM₁₀, NO₂, and CO has been found in all the regions during the lockdown. SO₂ showed mixed behavior, with a slight increase at some sites but a comparatively significant decrease at other locations. O₃ also showed a mixed variation with a mild increase in IGP and a decrease in the South. The absolute decrease in PM₂.₅, PM₁₀, and NO₂ was observed during peak morning traffic hours (08–10 Hrs) and late evening (20–24 Hrs), but the percentage reduction is almost constant throughout the day. A significant decrease in day-time O₃ has been found over Indo Gangetic plain (IGP) and central India, whereas night-time O₃ has increased over IGP due to less O₃ loss. The most significant reduction (∼40–60%) was found in PM₂.₅ and PM₁₀. The highest decrease in PM was found for the north-west and IGP followed by South and central regions. A considerable reduction (∼30–70%) in NO₂ was found except for a few sites in the central region. A similar pattern was observed for CO having a ∼20–40% reduction. The reduction observed for PM₂.₅, PM₁₀, NO₂, and enhancement in O₃ was proportional to the population density. Delhi’s air quality has improved with a significant reduction in primary pollutants, however, an increase in O₃ was observed. The changes reported during the lockdown are combined effect of changes in the emissions, meteorology, and atmospheric chemistry that requires detailed investigations.

Gradual contamination of agricultural land with copper (Cu), due to the indiscriminate uses of fungicides and pesticides, and the discharge of industrial waste to the environment, poses a high threat for soil degradation and consequently food crop production. In this study, we combined morphological, physiological and biochemical assays to investigate the mechanisms underlying acetate-mediated Cu toxicity tolerance in lentil. Results demonstrated that high dose of Cu (3.0 mM CuSO₄. 5H₂O) reduced seedling growth and chlorophyll content, while augmenting Cu contents in both roots and shoots, and increasing oxidative damage in lentil plants through disruption of the antioxidant defense. Principle component analysis clearly indicated that Cu accumulation and increased oxidative damage were the key factors for Cu toxicity in lentil seedlings. However, acetate pretreatment reduced Cu accumulation in roots and shoots, increased proline content and improved the responses of antioxidant defense (e.g. increased catalase and glutathione-S-transferase activities, and improved action of glutathione-ascorbate metabolic pathway). As a result, excess Cu-induced oxidative damage was reduced, and seedling growth was improved under Cu stress conditions, indicating the role of acetate in alleviating Cu toxicity in lentil seedlings. Taken together, exogenous acetate application reduced Cu accumulation in lentil roots and shoots and mitigated oxidative damage by activating the antioxidant defense, which were the major determinants for alleviating Cu toxicity in lentil seedlings. Our findings provide mechanistic insights into the protective roles of acetate in mitigating Cu toxicity in lentil, and suggest that application of acetate could be a novel and economical strategy for the management of heavy metal toxicity and accumulation in crops.

Liquid hydrocarbon pipeline accidents, including leaks due to the illegal or unauthorized collection of petroleum from oil pipelines, are a widespread phenomenon that can lead to pollution that may negatively affect soil quality and plant growth. The aim of this study is to evaluate hydrocarbon uptake and accumulation in Zea mays plants grown on soil affected by spills of fossil fuels. The experiments were conducted in microcosm, mesocosm and field tests. The potential transfer of contaminants from soil to plant and their effects on plant growth were investigated. The results from both the laboratory and field experiments showed that the plants grew better in the uncontaminated soil than in the soil polluted by hydrocarbons. Despite their significantly lower aerial biomass, plants grown in contaminated soil did not show any significant differences in C > 12 concentration, either in shoots or roots, compared to the control plants. Thus, the decrease in plant yield might not be attributed to hydrocarbons accumulation in the plant tissues and may rather be due to a reduced soil fertility, which negatively affected plant growth.Under our experimental conditions, the hydrocarbons present in the contaminated soil were not absorbed by the plants and did not accumulate in plant tissue or in grains, thus avoiding the risk of them entering the food chain.

Surface waters are becoming increasingly contaminated by pharmaceutically active compounds (PhACs), which is a potential risk factor for drinking water quality owing to incomplete riverbank filtration. This study examined the efficiency of riverbank filtration with regard to 111 PhACs in a highly urbanized section of the river Danube. One hundred seven samples from the Danube were compared to 90 water samples from relevant drinking water abstraction wells (DWAW) during five sampling periods. The presence of 52 PhACs was detected in the Danube, the quantification of 19 agents in this section of the river was without any precedent, and 10 PhACs were present in >80% of the samples. The most frequent PhACs showed higher concentrations in winter than in summer. In the DWAWs, 32 PhACs were quantified. For the majority of PhACs, the bank filtration efficiency was >95%, and not influenced by concentrations measured in the river. For carbamazepine lidocaine, tramadol, and lamotrigine, low (<50%) filtration efficiency was observed; however, no correlations were observed between the concentrations detected in the Danube and in the wells. These frequently occurring PhACs in surface waters have a relatively even distribution, and their sporadic appearance in wells is a function of both space and time, which may be caused by the constantly changing environment and micro-biological parameters, the dynamic operating schedule of abstraction wells, and the resulting sudden changes in flow rates. Due to the changes in the efficiency of riverbank filtration in space and time, predicting the occurrence and concentrations of these four PhACs poses a further challenge to ensuring a safe drinking water supply.

Plastic pollution has become a pressing issue due to its persistence in the environment. Smaller plastics are more easily ingested, potentially exerting greater influences on organisms. In this study, the effects of polystyrene nanoplastics (NP) on the toxic effects, bioaccumulation, biodegradation and enantioselectivity of ibuprofen (IBU) in algae Chlorella pyrenoidosa were explored. The influences on the growth rate, chlorophyll a, total antioxidant capacity (T-AOC), reactive oxygen species (ROS) and lipid peroxidation (MDA) were evaluated after 96 h of exposure to a combination of polystryene NP (1 mg L⁻¹) and IBU (5–100 mg L⁻¹). The results indicated that the inhibitory effect of IBU on C. pyrenoidosa growth was alleviated in the presence of NP. For instance, the 96 h-IC₅₀ value for rac-IBU in the treatment lacking NP was 45.7 mg L⁻¹, and the corresponding value in the treatment containing NP was 63.9 mg L⁻¹. The co-exposure of NP led to a significant enhancement of T-AOC and slight reduction of ROS and MDA compared with the individual exposure (IBU) group, suggesting a decreased oxidative stress. In addition, treatment with NP led to a decreased bioaccumulation and accelerated biodegradation of IBU in C. pyrenoidosa and enhanced removal in the medium. The enantioselective toxicity, bioaccumulation and biodegradation of IBU were observed both in the absence and presence of NP. S-IBU exhibited a greater toxicity, and R-IBU was preferentially accumulated and degraded in C. pyrenoidosa. No interconversion of the two enantiomers occurred regardless of the presence of NP. This consequence implied that the influence of coexistent NP should be considered in the environmental risk assessment of pharmaceuticals and personal care products in aquatic environments.

Plant species occurrence in Europe is affected by changes in nitrogen deposition and climate. Insight into potential future effects of those changes can be derived by a model approach based on field-based empirical evidence on a continental scale. In this paper, we present a newly developed empirical model PROPS, predicting the occurrence probabilities of plant species in response to a combination of climatic factors, nitrogen deposition and soil properties. Parameters included were temperature, precipitation, nitrogen deposition, soil pH and soil C/N ratio. The PROPS model was fitted to plant species occurrence data of about 800,000 European relevés with estimated values for pH and soil C/N ratio and interpolated climate and modelled N deposition data obtained from the Ensemble meteo data set and EMEP model results, respectively. The model was validated on an independent data set. The test of ten species against field data gave an average Pearson’s r-value of 0.79.PROPS was applied to a grassland and a heathland site to evaluate the effect of scenarios for nitrogen deposition and climate change on the Habitat Suitability Index (HSI), being the average of the relative probabilities, compared to the maximum probability, of all target species in a habitat. Results for the period 1930–2050 showed that an initial increase and later decrease in nitrogen deposition led to a pronounced decrease in HSI, and with dropping nitrogen deposition to an increase of the HSI. The effect of climate change appeared to be limited, resulting in a slight increase in HSI.

Glandless cotton can be grown to obtain cotton seeds free of toxic gossypol for use as both food and feed. However, they are not grown normally due to their lesser productivity and higher susceptibility to biotic stress. Great attention has been paid to biotic stresses rather than abiotic stresses on glandless cotton. Chromium (Cr) is a common pollutant of soil and considered a serious threat to plants due to its adverse effects on different functions. Although numerous studies are available on the toxicity of Cr⁶⁺ in various plants. However, its adverse effects and mechanism of toxicity in glandless cotton can seldom be found in the literature. This study examined the Cr⁶⁺ effect on glandless cotton in comparison to glanded cotton. Four pairs of glanded and glandless cotton near-isogenic lines (NILs) were exposed to different doses (0, 10, 50, and 100 μM/L) of Cr⁶⁺ for seven days, and biochemical, physiological, molecular, and ultrastructure changes were observed, which were significantly affected by Cr⁶⁺ at high concentrations in all NILs. The effect of Cr⁶⁺ on ionic contents shows the same trend in glanded and glandless NILs except for manganese (Mn²⁺) that show inhibition in glandless (ZMS-12w and Coker-312w) and enhance in the glanded NIL (ZMS-17). The gene expression of superoxide dismutase (SOD) and peroxidase (POD) revealed similar trends as enzyme activities in glandless NILs. The principal component analysis (PCA) and Agglomerative hierarchical clustering (AHC) results of all NILs from morpho-physiological traits, cluster ZMS-16, and ZMS-17 into Cr⁶⁺ sensitive group. While the glandless NILs have the potential to cope with the Cr toxicity by increasing the antioxidant enzyme activity and their gene expression. This study also revealed that Cr⁶⁺ tolerance in cotton is genotypic and has an independent mechanism in the root that not related to low gossypol.

Based on the archival data on oil facilities, oil spill incidents, and environmental conditions, we researched the plausible causes of oil spill disasters in the Niger Delta of Nigeria between 2006 and 2019. The data were analyzed for geospatial and statistical patterns, using ArcGIS and R programming platforms, respectively. A fuzzy logic algorithm was employed to generate three oil spill disaster models (hazard, vulnerability, and risk). Ordinary Least Square algorithm was adopted to model the relationships between oil spill and two sets of predictor variables: oil facilities (oil well, flow station, and pipeline) and disaster models. We found that, during the 23 years, the Niger Delta experienced 7940 oil spill incidents, of which 67% occurred onshore. A total of 4,950, 501, 855 episodes were attributed to sabotage, corrosion, and equipment failure, with 87%, 62%, and 45% occurring onshore, respectively. Besides, 81% of the 5320 onshore oil spill cases were attributed to sabotage, while corrosion and equipment failure accounted for mere 6% and 7% of the incidents, respectively. The estimated average risk index (R = 0.20) shows that the risk of an oil spill disaster in the Niger Delta is low. Whereas, 5% of the region is characterized by a high risk of oil spill disaster. Furthermore, the regression model infers that the oil spillages exhibit a positive relationship with disaster models and oil facilities at α = 0.10. However, only 16% of the incidents were explained by disaster models, while the oil facilities account for 23% of the total cases, indicating the influence of other factors. To avert further socio-environmental damage in the Niger-Delta, oil theft and sabotage should be curbed, polluted areas are remediated, and an all-inclusive socio-economic development is prioritized.

Excess fluoride in drinking water is an environmental issue of increasing worldwide concern, because of its adverse effect on human health. Skeletal fluorosis caused by chronic exposure to excessive fluoride is a metabolic bone disease characterized by accelerated bone turnover accompanied by aberrant activation of osteoblasts. It is not clear whether Wnt/β-catenin signaling, an important signaling pathway regulating the function of osteoblasts, mediates the pathogenesis of skeletal fluorosis. A cross-sectional case-control study was conducted in Tongyu County, Jilin Province, China showed that fluoride stimulated the levels of OCN and OPG, resulting in accelerated bone turnover in patients with skeletal fluorosis. To investigate the influence of fluoride on Wnt/β-catenin signaling pathway, 64 male BALB/c mice were allotted randomly to four groups and treated with deionized water containing 0, 55, 110 and 221 mg/L NaF for 3 months, respectively. The results demonstrated that fluoride significantly increased mouse cancellous bone formation and the protein expression of Wnt3a, phospho-GSK3β (ser 9) and Runx2. Moreover, partial correlation analysis indicated that there was no significant correlation between fluoride exposure and Runx2 protein levels, after adjusting for β-catenin, suggesting that β-catenin might play a crucial role in fluoride-induced aberrant osteogenesis. In vivo, viability of SaoS2 cells was significantly facilitated by 4 mg/L NaF, and fluoride could induce the abnormal activation of Wnt/β-catenin signaling, the expression of its target gene Runx2 and significantly increased Tcf/Lef reporter activity. Importantly, inhibition of β-catenin suppressed fluoride-induced Runx2 protein expression and the osteogenic phenotypes. Taken together, the present study provided in vivo and in vitro evidence reveals a potential mechanism for fluoride-induced aberrant osteoblast activation and indicates that β-catenin is the pivot molecule mediating viability and differentiation of osteoblasts and might be a therapeutic target for skeletal fluorosis.

A compound system involving three matrices (water, sediment, and paddy soil) was conceived to determine the potential sources of metal(loid)s (Ti, Fe, Co, Ni, Cu, Zn, As, Cd, Pb, and U) and synthetically evaluate their pollution levels in the Le’an River basin. The result indicated that the established background values (BVs) of paddy soil and sediment in the compound system were obviously higher than those of the upper continental crust (UCC) and soils from Jiangxi Province, a difference which was especially marked for sediment. The concentrations of Cu, Zn, As, Cd in the system had high coefficients of variation (CVs), and metal(loid)s in sediment showed higher levels than those in paddy soil, except for Pb. Cd and Cu in the system had the highest Ef levels, which probably pose a high risk to organisms and the health of local residents. There were significantly linear relationships between the site rank index (SRI) for water and that for sediment or paddy soil, revealing that matrices in the system interacted with each other. Principal component analysis (PCA) and absolute principal component scores and multiple linear regression model (APCS-MLR) results demonstrated that Cu, Zn, As, Cu, Pb, and U enrichments in the system were mainly affected by mining activities and were predominately deposited in sediment. Point pollution sources rather than non-point pollution sources such as mining activities, contributed most of the anthropogenic metal(loid)s to sediment. Both SRI and Hierarchical cluster analysis (HCA) results visually showed that S5, S8, S9, S10, S11, and S12 severe pollution grouped together and scattered through areas with extensive mining activities, while other sites with moderate pollution were spread along the main stream of the Le’an River.