Changes in crude oil production and distribution have increased the incidence of oil spills throughout the world. Oil spills often cause destructive effects on aquatic and land ecosystems. The oil spill cleanup and recovery techniques are challenging and usually involve complex mechanical, chemical, and biological methods. Usually, mechanical removal of free oil is utilized as an effective strategy for cleanup in aquatic and terrestrial environments; however, they are expensive and need specialist personnel and equipment. The other commonly used method is the application of chemical materials such as dispersants, cleaners, demulsifiers, biosurfactants, and soil oxidizers. Nevertheless, these reagents can have potential harmful environmental impacts, which may limit their application. As an alternative, bioremediation can offer reduced environment risk; however, the limitations of microbial activity in the soil can make this option unsuitable. One area of bioremediation is phytoremediation, which offers potential for restoring large areas of contaminated ground. Plants are able to remove pollutants through processes such as biodegradation, phytovolatilization, accumulation, and metabolic transformation. This review presents the fate of crude oil spills in aquatic and land ecosystems and their environmental effects. Furthermore, the paper focuses on crude oil phytoremediation and its applications in polluted ecosystems.

Mg, Zn, Mn, and Al oxide powders have been synthesized through chemical combustion and calcination methods to compare their CO₂ capture performances. The characteristic properties of the adsorbents were evaluated by X-ray diffraction analysis, scanning electron microscopy, and N₂ physisorption measurements. The porous γ-Al₂O₃ prepared through combustion with a BET-specific surface area of 192.1 m²/g, achieving a maximum gas adsorption capacity of 1.71 mmol/g at 60 °C and 1.5 MPa. The MgO adsorbent performed poorly during CO₂ capture, while that Zn and Mn oxides showed no CO₂ adsorption. The results showed theoretical contribution to the field of separation science.

The internal concentration represented by the critical body residue (CBR) is an ideal indicator to reflect the intrinsic toxicity of a chemical. Whilst some studies have been performed on CBR, the effect of exposure route on internal toxicity has not been investigated for fish. In this paper, acute toxicity data to fish comprising LC₅₀ and LD₅₀ values were used to investigate CBR. The results showed that exposure route can significantly affect the internal concentration. LD₅₀ and CBR calculated from LC₅₀ and BCF both vary independently of hydrophobicity as expressed by log Kₒw; conversely, LC₅₀ is related to log Kₒw. A poor relationship was observed between LC₅₀ and LD₅₀, but the relationship can be improved significantly by introduction of log Kₒw because log CBR is positively related to log LD₅₀. The parallel relationship of log CBR-log Kₒw and log LD₅₀-log Kₒw indicates that LD₅₀ does not reflect the actual internal concentration. The average LD₅₀ is close to the average CBR for less inert and reactive compounds, but greater than the average CBR for baseline compounds. This difference is due to the lipid fraction being the major storage site for most of the baseline compounds. Investigation on the calculated and observed CBRs shows that calculated CBRs are close to observed CBRs for most of compounds. However, systemic deviations of calculated CBRs have been observed for some compounds. The reasons for these systemic deviations may be attributed to BCF, equilibrium time and experimental error of LC₅₀. These factors are important and should be considered in the calculation of CBRs.

A novel cerium-loaded cellulose nanocomposite bead (CCNB) is synthesized and tested for fluoride adsorption. The optimization of the process under the cooperative influence of different experimental variables was made employing response surface methodology (RSM). It is found from fractional factorial design (FFD) that among the different experimental variables, only adsorbent dose, temperature, and pH are significant. At the optimum condition (adsorbent dose 1 g L⁻¹, temperature 313 K, pH 3.0), a maximum fluoride adsorption of 94 % was observed for an initial fluoride concentration of 2.5 mg L⁻¹. A quadratic polynomial model equation based on central composite design (CCD) was built to predict the extent of adsorption. The result of the analysis of variance (ANOVA) shows high coefficients of determination (correlation coefficient; R² = 0.9772, adjusted R² = 0.9545, and adequate precision = 18.1045) and low probability value (Prob > F, 0.001) which signifies the validity of the model. The equilibrium adsorption data conformed to the Tempkin isotherm, having higher R²and lower SE value, among the Langmuir, Freundlich, and Tempkin equations at different temperatures. The adsorption data was found to fit well the second-order rate equation with film diffusion governing the overall rate. The activation energy value was calculated to be 16.74 kJ mol⁻¹. Fluoride can be eluted from fluoride-loaded CCNB using alkali. CCNB can be reused at least for five successive operations.

Macroscopic (germination and root growth) and microscopic (mitotic index, chromosome, and nuclear aberrations) analyses have been used to determine the toxicity of environmental pollutants. To better understand the molecular mechanisms of mutation and their effects, molecular markers offer a key perspective, as they measure the direct effects of DNA mutagenic agents. The aim of this study was to evaluate the toxic potential of the fungicides difenoconazole (DZ) and tebuconazole (TZ) on Allium cepa. A reduction was observed in the germination, root growth, and mitotic index at higher concentrations of DZ and TZ, compared to the negative control. In addition, high incidence of chromosome and nuclear aberrations was detected in treated roots. This demonstrates the genotoxic, cytotoxic, and phytotoxic effects of DZ and TZ on the root tips of A. cepa. Moreover, the molecular results indicate a change in the amplification profiles of the simple sequence repeats (SSR) and intersimple sequence repeats (ISSR) obtained from A. cepa after exposure to the tested compounds. Loss and gain of bands increased dose-dependently. Further, the grouping methods distinguished the higher concentrations from the negative control. The ISSR and SSR analyses proved to be efficient tools for evaluating DNA alterations caused by DZ and TZ. In association with macroscopic and microscopic analyses, they constitute an informative approach for environmental mutagen studies.

The behaviour of sulphate-reducing microbial community was investigated at the oxic–anoxic interface (0–2 cm) of marine sediments when submitted to oil and enhanced bioturbation activities by the addition of Hediste diversicolor. Although total hydrocarbon removal was not improved by the addition of H. diversicolor, terminal restriction fragment length polymorphism (T-RFLP) analyses based on dsrAB (dissimilatory sulphite reductase) genes and transcripts showed different patterns according to the presence of H. diversicolor which favoured the abundance of dsrB genes during the early stages of incubation. Complementary DNA (cDNA) dsrAB libraries revealed that in presence of H. diversicolor, most dsrAB sequences belonged to hydrocarbonoclastic Desulfobacteraceae, suggesting that sulphate-reducing microorganisms (SRMs) may play an active role in hydrocarbon biodegradation in sediments where the reworking activity is enhanced. Furthermore, the presence of dsrAB sequences related to sequences found associated to environments with high dinitrogen fixation activity suggested potential N₂ fixation by SRMs in bioturbated-polluted sediments.

The aim of this study was to describe the mechanisms that native Bacillus cereus M6 isolated from heavy crude oilᵒAPI gravity 11.5 uses to tolerate and/or resist toxic metals. Metal tolerance and removal of Pb(II), Cr(VI), and As(V) was determined. In addition, we evidenced the subcellular distribution of metals, the efflux pump kinetics, and morphological changes in metal-tolerant bacteria. B. cereus M6 exhibited strong tolerance and resistance to the metals evaluated and efficiently removed the metal content by operating efflux pumps and accumulating mainly in membrane fraction. Also, it was found that the model that best fit the efflux corresponds to an equation for resonant oscillations. B. cereus M6 uses mechanisms, including efflux pumps, intracellular and extracellular accumulation in parallel in order to maintain metal levels below a toxic threshold and overcome the effects of high concentrations. These findings are an approach of an energy-dependent efflux system to eliminate excessive amounts of crude oil-associated metals in Bacillus. B. cereus M6 may potentially be useful in designing improved strategies for the bioremediation of soils polluted with metals. Additionally, the prediction model developed would be useful for improving the monitoring of in vitro and in vivo bioremediation processes.

Fe₃O₄and Fe₃O₄/bentonite were prepared by chemical co-precipitation method. They were characterized by X-ray powder diffraction (XRD), Fourier infrared spectroscopy (FTIR), and transmission electron microscope (TEM). Adsorption of cobalt(II) on the bentonite, Fe₃O₄, and Fe₃O₄/bentonite nanocomposite was studied. The results indicated that the metal oxides mainly occurred in the form of spinel structure of Fe₃O₄and the presence of Fe₃O₄significantly affect the surface area and pore structure of the bentonite. The specific surface area (Brunauer–Emmett–Teller (BET) method) of bentonite, Fe₃O₄, and Fe₃O₄/bentonite were determined to be 34.44, 98.44, and 140.5 m² g⁻¹, respectively. TEM image of Fe₃O₄/bentonite shows the particle diameter at 10 nm. The maximum adsorption capacity of cobalt(II) by Fe₃O₄/bentonite nanocomposite was determined to be 18.76 mg g⁻¹. The adsorption strongly depends on pH, where the removal efficiency increases as the pH turns to alkaline range (pH 9). The results suggest that higher adsorption capacity of composite than bentonite is attributed to the presence of Fe₃O₄. The adsorption process follows pseudo-second-order kinetics. The equilibrium data was analyzed by Langmuir model showing high correlation coefficient. The thermodynamic study of adsorption process showed that the adsorption of Co(II) onto Fe₃O₄/bentonite was carried out spontaneously.

To test the hypothesis that lead (Pb) content of rice grain may be related to its transport and subcellular distribution in rice plant, the present study was conducted with six rice cultivars of different types under different soil Pb levels. The results showed that grain Pb concentrations were correlated positively and significantly (P < 0.05 or 0.01) with distribution ratios (DRs) of Pb from shoots to ears/grains, but insignificantly (P > 0.05) with the DR from roots to shoots. The DR from shoots to ears/grains was correlated positively and significantly (P < 0.05 or 0.01) with subcellular distribution ratios (SDRs) of Pb in soluble fraction of shoots, but negatively and significantly (P < 0.05 or 0.01) with the SDR in cell wall fraction of shoots. In conclusion, Pb transportation from the shoot to the grain is the key factor in determining Pb content of rice grain. The Pb distributed in soluble fraction of shoot tissue is the key source of Pb for transferring into the grain. The Pb precipitated in cell wall fraction is the key sink of Pb in shoot tissue that restricts the transport of Pb from the shoot to the grain.

Thifluzamide fungicide is widely used to protect rice (Oryza sativa) against the sheath blight fungus (Rhizoctonia solani). The continuous application of thifluzamide may lead to accumulation in soil and contaminate rice crop. To sustain the environment, it is necessary to assess its accumulation and degradation in field. The method limit of detection (LOD) was 0.022 ng. The limits of quantitation detection (LOQ) were 5.0 μg L⁻¹in water and 4.0 μg kg⁻¹in paddy soil and rice crop. In this study, a 2-year (2011–2012) field study was performed to monitor thifluzamide degradation in the rice production areas of Nanjing, Xiaoxian, and Changsha. The degradation dynamics of thifluzamide in paddy water, paddy soil, and rice crop were well described by the first-order kinetics equation. The 2-year average half-lives of thifluzamide in paddy water, paddy soil, and rice crop were 26.19, 17.92, 14.61 days (Nanjing), 15.63, 20.71, 9.10 days (Xiaoxian), and 9.47, 13.92, 10.08 days (Changsha), respectively. Thifluzamide degraded more rapidly in rice crop than in soil and paddy water. The variation in thifluzamide degradation was attributed to the difference in rainfall during the period of rice cultivation. The maximum residue of thifluzamide in brown rice was 0.0303 mg kg⁻¹in Nanjing and the residue of thifluzamide in brown rice was not detected in other two sites before thifluzamide was applied at pre-harvest. The experimental data demonstrated that thifluzamide recommended dosage of 72 g a.i.ha⁻¹can be used in rice fields with less than three times within a 30-day time interval.