Soil potentially toxic metals (PTMs) pollution caused by anthropogenic activities has become serious concern with respect to the crop safety production. In this study, an emerging biochar derived from kiwi pruning branches waste was employed as amendment aiming to evaluate its remediation potential on smelter- and mining-contaminated soils. The effect of biochar on the soil physicochemical properties, leachability, and chemical fractions acted on stabilization practice of PTMs in soil was investigated. The results showed that the addition of biochar increased the soil pH, cation exchange capacity, organic matter, and enzymatic activities (dehydrogenase, urease, and sucrase) but reduced the extraction toxicity of PTMs in both smelter (Fengxian, FX) and mining (Tongguan, TG) soils. The fraction analysis showed that the maximum reduction of exchangeable fraction of Cd, Zn, and Pb in the 4% biochar amended soils decreased by 11.1, 13.3, and 24.7% in FX soil and 7.67, 22.8, and 7.89% in TG soil, respectively, in comparison with to control (no biochar added). Additionally, the residual fraction of Cd, Zn, and Pb increased by 55.9, 7.14, and 11.0% in FX soil and 23.7, 5.86, and 10.0% in TG soil, respectively. The further greenhouse experiment showed that the Indian mustard (Brassica juncea) production increased with the increasing application dosages of biochar, while the PTMs uptakes in plant notably decreased after amendments. Conversion of kiwi pruning branches waste into emerging biochar benefits the agricultural waste recycling utilization and enhances PTMs-contaminated soil remediation in practice. Graphical abstract

Fipronil (FPN) is a relatively new and broad spectrum insecticide that induces toxic effects to animals and humans through induction of oxidative stress. Ginseng is a medicinal plant that has antioxidant, anti-inflammatory, and anti-apoptotic activities. Thus, the current study was conducted to evaluate the anti-toxic potential of ginseng aqueous extract (GAE) against FPN-induced hepatorenal toxicity in rats. Thirty-two male Wistar albino rats were randomly allocated into four equal groups. Rats of the control group received distilled water. The second group was administrated with GAE at a dose of 200 mg/kg b.w. orally day by day for 6 weeks. The third group was intoxicated with FPN at a dose of 4.85 mg/kg b.w. orally day by day for 6 weeks. The fourth group was administrated with GAE 2 h before FPN intoxication. Intoxication of rats with FPN significantly elevated the activities of serum alanine aminotransferase and aspartate aminotransferase and serum levels of urea and creatinine, as well as increased malondialdehyde level and protein expressions of caspase-3 and cyclooxygenase-2 in hepatic and renal tissues. However, it significantly decreased hepatic and renal GSH content and catalase activity. In addition, it induced histopathological alterations in hepatic and renal tissue architectures. Conversely, concomitant oral administration of GAE ameliorated the FPN-induced biochemical, pathological, and histochemical alterations in both hepatic and renal tissues. This study indicated that ginseng attenuates FPN-induced hepatorenal toxicity, possibly via its antioxidant, anti-apoptotic, and anti-inflammatory properties. Graphical Abstract CAL ABSTRACTPHIRAG

The evaluation of microplastic (MP) pollution has been drawing attention for the last decades. MP pollution has been studied widely in marine environments, but limited data exists for freshwater ecosystems on potential source and transport of MPs. The type, shape, plastic components, and the color of the MPs were investigated using various-mesh-sizes (300 and 100 μm) nets in four sampling stations of Süreyyabey Dam Lake in Turkey. The growth of bacterial isolates on the MPs surface and surrounding water was also investigated. The type of the MPs and the interaction between the mesh size and the type of the MPs showed significant differences (p < 0.05). Fibers were found to be the most abundant particle type constituting 45% and 80% of the total MPs found in 330-μm and 100-μm mesh sizes, respectively. In total the observed MP abundance in the dam lake was 5.25 particles m⁻³, and 4.09 particles m⁻³ was observed for 100-μm and 330-μm mesh sizes, respectively. The color of the identified microplastics showed variations among microplastic types; however, the dominant color was transparent in each net. The main plastic components of the MPs are polyethylene terephthalate, polyvinyl chloride, polystyrene, polyethylene, and polypropylene. The microbial community mainly consists of potentially pathogenic strains such as Escherichia coli, Enterococcus faecalis, and Acinetobacter baumanii complex. The current study could contribute valuable background information both for MP pollution and for biofilm composition in a dam. However, the surface of the MPs and biofilm formation should be investigated urgently to understand the vector potential of MPs.

Fractal geometry is widely applied in the process description of contaminant transport, but few studies quantify the complexity of contaminant plume in the time series. Although the required accuracy is outside the scope of existent characterization methods, the model of solute transport remains the most sensitive issue for researchers due to its fractal behaviour. In this paper, a synthetic model is firstly presented under the condition of homogeneous/heterogeneous aquifer with different dispersivities and numbers of continuous point leakage sources. The new Hausdorff fractal dimension for the contaminant plume in the time series is obtained by the 3D box-counting method. According to the comparison among different hydro-geologic conditions, the result shows that the complexity of the contaminant plume decreases to the constant value with the passage time when the dispersivity increases and the number of point leakage sources rises. The decreasing fractal dimension is matched with the power-exponential function. The effect resulted from the number of point sources is tended to be weak when the amount is enormous. It is showed that the number of point leakage sources does not make a noticeable distinction in the homogeneous and heterogeneous aquifers.

Urinary benzene, toluene, ethylbenzene, and xylenes (BTEX) can be used as a reliable biomarker of exposure to these pollutants. This cross-sectional study aimed to employ biomonitoring to assess BTEX exposure among South Pars Gas Field (SPGF) workers in Assaluyeh, Iran. Forty employees who were working on the site were recruited as the case group. Besides, 31 administrative employees were recruited as the control group. Pre-shift and post-shift spot urine samples were collected from the subjects in the case group, while the subjects in the control group provided mid-morning urine samples. Overall, 111 urine samples, including 80 samples from the case group and 31 samples from the controls, were collected. Gas chromatography-mass spectrometry (GC/MS) was used to determine the urinary levels of BTEX compounds. The median urinary levels of benzene, toluene, ethylbenzene, m,p-xylene, and o-xylene in the post-shift samples of the exposed group were 1.24, 2.28, 0.5, 1.32, and 1.5 μg/l, respectively. Significant differences were observed in urinary BTEX levels among smokers and non-smokers in both studied groups (p < 0.05). Accordingly, the median urinary BTEX concentrations in smokers were 2 to 6.5 times higher than the corresponding values in non-smoker subjects. Smoking status was the only predictor of the urinary BTEX concentration. Our findings revealed that refinery workers are exposed to significant levels of BTEX compounds. Considering the health risks associated with BTEX exposure for refinery workers, implementation of suitable control strategies, such as using appropriate personal protective equipment and improving on-site ventilation systems, are recommended reducing their exposure to BTEX via the inhalation.

Magnetic magnesium-zinc spinel ferrite Mg₁ ₋ ₓZnₓFe₂O₄ (where x = 0.4, 0.6, and 0.8) was investigated as adsorbent for the efficient removal of Sr(II) ions and salicylic acid (SA) contaminants from aqueous medium. The characterization of ferrites was carried out using XRD, VSM, BET, SEM, and EDS. The surface charge of magnetic adsorbents was measured by the drift method. The determination of SA and Sr(II) ion concentrations in the solution phase was carried out by UFLC and complexometry, respectively. It was shown that varying of the Zn(II) content affected the adsorption capacities of magnesium-zinc ferrites. The increasing of zinc content from x(Zn²⁺) = 0.4 to x(Zn²⁺) = 0.6 increased the adsorption of Sr(II) ions from 50 to 65 mg/g, and then it was decreased to 36 mg/g for the sample with x(Zn) = 0.8. The Mg₀.₄Zn₀.₆Fe₂O₄ sample demonstrated the maximum adsorption capacity of 74 mg/g. The adsorption isotherm for Sr(II) was fitted by the Dubinin-Radushkevich, Langmuir, Freundlich, and Sips models. The adsorption kinetics of Sr(II) was analyzed by PFO, PSO, and Elovich models. The adsorption kinetics of SA was also investigated. It was demonstrated that the Mg₀.₂Zn₀.₈Fe₂O₄ sample exhibited 90% removal of salicylic acid from the water solutions. The results demonstrated that magnetic Mg-Zn ferrites with spinel structure are good sorbents for the removal of SA and Sr(II) ions from aqueous solution.

The Loess Plateau is the largest apple cultivation region in the world. However, the role of rain-fed apple orchards as carbon sinks or sources, including the dynamic variation and influencing factors, are still unclear. In this study, the net ecosystem CO₂ exchange (NEE) was monitored by an eddy covariance (EC) system in Loess Plateau apple orchards during 2016–2017. The results demonstrated that the annual NEE was higher in 2016 (− 698.0 g C m⁻² year⁻¹) than in 2017 (− 554.0 g C m⁻² year⁻¹). Particularly, the amount of orchard CO₂ uptake was significantly greater in 2016 (− 772.0 g C m⁻²) than in 2017 (− 642.1 g C m⁻²) during the carbon sink period. This difference may be attributed to the higher NEE in 2016 compared to 2017 during the fast and slow growth periods. In addition, a higher daily NEE occurred to the higher air temperature (Tₐ), which promoted early sprouting in 2016 (− 3.91 g C m⁻² day⁻¹) compared to 2017 (− 2.86 g C m⁻² day⁻¹) during the fast growth period. The daily NEE in 2016 (− 2.59 g C m⁻² day⁻¹) was remarkably higher than that in 2017 (− 1.41 g C m⁻² day⁻¹) during the slow growth period, owing to the greater number of cloudy and rainy days and lower temperatures in 2017. Overall, the present study demonstrated the key role played by the amount of precipitation and temperature in regulating the NEE during the growth season and provided accurate quantitative information on the carbon budget in apple orchards. Graphical abstract

Copper contamination of industrial waste streams is increasingly common with copper used in an array of industrial processes. Phytoremediation of copper-contaminated water with Pistia stratiotes presents a cost-effective, efficient and uncomplicated alternative for copper removal from industrial wastewater. This study examines the ability of Pistia stratiotes to remove copper from distilled water representing a highly nutrient-deficient medium and natural surface water containing plant nutrients inherently. Control and experimental sets were set up with growth solutions of distilled water and natural surface water spiked with 5 g/mL, 10 g/mL, 15 g/mL, 20 g/mL and 25 g/mL copper. The control sets were devoid of Pistia stratiotes while the experimental sets contained Pistia stratiotes. Copper concentration and pH of the solutions were tracked over 10 days. This study revealed the ability of Pistia stratiotes to remove copper in both types of growth solution with contamination level ranging from 5 to 25 mg/L and pointed to its ability to phytoremediate higher level of copper contamination. Pistia stratiotes also raised the pH of the growth solutions. Copper removal from both types of growth solution demonstrated a predominantly first-order elimination kinetics except for copper concentrations above 15 mg/L in distilled water where the zero-order elimination kinetics predominated. Copper removal efficiency decreased with increasing copper concentrations in both types of growth solution with removal efficiency in natural surface water growth solutions consistently higher. It highlights the ability of Pistia stratiotes to phytoremediate highly nutrient-deficient and natural surface water media.

In order to unravel the cadmium (Cd) enrichment patterns in rice (Oryza sativa L.) grown under different exogenous exposure pathways, the pot experiment was conducted in a greenhouse. Cd was added to the soil-rice system via mixing soil with Cd-containing solution, irrigating the pots with Cd-containing water and leaf-spraying with Cd solution to simulate soil pollution (SPS), irrigation water pollution (IPS), and atmospheric deposit pollution sources (APS), respectively. No significant (p > 0.05) differences in plant height and rice grain yield were observed among all treatments including three different Cd pollution sources and control. The contents of Cd in rice plants significantly (p < 0.05) increased with increase in Cd concentrations in three pollution sources. The distribution pattern of Cd in the rice plant organs treated with SPS and IPS followed the order: roots > stems > leaves > husk > brown rice, while it was leaves > roots > stems > husk > brown rice treated with APS. At the same level of treatment, the highest concentration of Cd was observed in rice organs (except for middle and high concentrations treatment roots) grown under APS, followed by IPS and SPS, suggesting that the Cd bioavailability from different pollution sources followed the order of APS > IPS > SPS. It is concluded that the atmospheric pollution contributed more enrichment of rice with Cd. Therefore, in field environment, air deposits should also be analyzed for toxic metals during assessment of food chain contamination and health risk.

The enzymatic reactions of microbial communities are rapid and adequate to changes in the composition of organic matter and environmental factors; therefore, they can be used as descriptors of biological responses in freshwater systems. The objective of this work was to determine the proteolytic enzymatic activity in the Almendares and San Juan rivers (western Cuba) and their relationship with physicochemical and microbiological indicators. The Almendares River (Havana, Cuba) presented water quality index between very poor and unusable for consumption, which makes impossible for recreational uses. In contrast, the waters of the San Juan River (Artemisa, Cuba) are classified as excellent and good in most of the sampling stations during the study period. The greatest proteolytic activities were detected in the San Juan River compared to the Almendares River, which indicates that in more contaminated ecosystems, the proteolytic enzyme activity decreases compared to another less impacted system. In addition, the annual variation in the proteolytic activity of both rivers was evidenced. In the San Juan River, a correlation was observed among proteolytic activity, the concentration of proteolytic bacteria and the physicochemical indicators of water quality, suggesting that proteolytic activity is related to naturally occurring contaminants. In contrast, in the Almendares River, this relationship was not observed, which suggests that the proteolytic activity is not directly affected by the indicators measured in this study.