Ammonia-oxidixing bacteria (AOB) and archaea (AOA) mediate the first and rate-limiting step of nitrification and are responsive to agricultural management practices. These two attributes make them ideal indicators of biological soil health. We conducted a laboratory incubation study to determine their response to elevated levels of zinc (Zn) and copper (Cu) in poultry litter treated soil at three substrate concentrations: 0 (low), 50 (medium) and 100 (high) mg ammonium ([Formula: see text]-N) kg⁻¹ soil. Nitrification potential (NP) was measured to characterize changes in their function in which 1-octyne was used to separate their contributions. Quantitative polymerase chain reaction was used to measure their abundance by targeting amoA. Increasing Zn from 21 to 250 mg kg⁻¹ resulted in large reductions in AOB (78%) and AOA (85%) abundance at the high [Formula: see text] level over 28 days. Likewise, increasing Cu from 20 to 120 mg kg⁻¹ significantly reduced AOB (92%) and AOA (63%) abundance at the high [Formula: see text] level over 28 days. The relative contribution of AOB to NP was significantly higher than that of AOA in both Zn (~60%) and Cu (~70%) treated soils despite the numerical dominance of AOA over AOB. Overall, results indicate that elevated levels of Zn and Cu depressed AOB and AOA abundance and function and that their effect was dependent on availability of [Formula: see text]. The results also indicated that AOB are functionally more important than AOA under elevated Zn and Cu concentrations and that management practices to improve N use efficiency should focus on AOB under this condition.

Surfactants are considered promising and practical substances for enhancing polycyclic aromatic hydrocarbon (PAHs) removal from contaminated soil. In order to explore the effects of single and mixed surfactants on the removal of high-concentration PAHs from soil, a series of experiments have been conducted. In this study, Tween80-saponin (a mixed surfactant), Tween80 (a nonionic surfactant), and saponin (a biosurfactant) were used to remove two typical and high concentration PAHs (anthracene and pyrene) from contaminated soil. Results showed that the mixed surfactant had better performance on the solubilization of anthracene and pyrene than Tween80, but its performance was worse than saponin. When the proportion and concentration of the mixed surfactant were 1:9 and 800 mg L⁻¹ respectively, the elution rate of anthracene could reach 97.67%, it was better than that by Tween80 and saponin. In addition, the Tween80-saponin mixed surfactant had good performance on actual PAHs contaminated soil remediation. When the proportion and concentration of Tween80-saponin were 1:9 and 800 mg L⁻¹ respectively, the PAHs elution rate of actual contaminated soil could reach 81.31%.

The efficient removal of heavy metals from aqueous environment is imperative and challenging. A novel ternary composite constructed of diaminopyridine polymers, graphene oxide, and ferrite magnetic nanoparticles was designed by a facile in situ polymerization strategy for the removal of Pb(II) from aqueous solution. Detailed characterization of morphological, chemical, and magnetic properties was employed systematically to confirm the formation of the composite material. Batch adsorption experiment studies suggested that the composite was an excellent adsorbent for Pb(II) which was easily collected after use via exposure to an external magnetic field for 30 s. The effects of different parameters such as solution pH, adsorbent dosage, contact time, initial Pb(II) concentration, temperature, and co-existing ions were examined. The maximum adsorption capacity at pH = 5 was estimated to be 387.2 mg g⁻¹ at 298 K by the Langmuir isotherm model, accompanied by favorable adsorption recyclability according to the investigation of regeneration experiments. Thermodynamic studies revealed that the Pb(II) adsorption via our ternary composite was endothermic and spontaneous. The corresponding removal performance for effluent containing Pb(II) from the battery industry was successfully examined. The present results indicated that our designed adsorbent is beneficial to the practical Pb(II) removal in wastewater purification.

Steady efforts in using ultrasonic energy to treat oil-contaminated sand started in the early 2000s until today, although pilot studies on the area can be traced to even earlier dates. Owing to the unique characteristics of the acoustic means, the separation of oil from sand has been showing good results in laboratories. This review provides the compilation of researches and insights into the mechanism of separation thus far. Related topics in the areas of oil-contaminated sand characterizations, fundamental ultrasonic cleaning, and cavitation effects are also addressed. Nevertheless, many of the documented works are only at laboratory or pilot-scale level, and the comprehensive interaction between ultrasonic parameters towards cleaning efficiencies may not have been fully unveiled. Gaps and opportunities are also presented at the end of this article.

The increasing scarcity of arable land necessitates the development of effective decontamination techniques to re-gain contaminated areas and make them suitable for agricultural and other activities. Herein, we prepare a ferromanganese binary oxide-biochar composite (FMBC) and compare its potential for remediating Cd-contaminated red soil with that of biochar (BC), showing that (i) the obtained adsorption data are well described by the Langmuir model and (ii) Cd adsorption capacity increases with increasing adsorbent dosage. Specifically, the Cd adsorption capacity of FMBC-amended soil (6.72 mg g⁻¹) is demonstrated to significantly exceed that of BC-amended red soil (4.85 mg g⁻¹) and that of the control (2.28 mg g⁻¹) and increases with increasing temperature and pH, while the results of instrumental analyses indicate that Cd sorption on the soil surface occurs via the formation of CdO and Cd(OH)₂. Thus, FMBCs are concluded to play an important role in the adsorption of Cd, having the potential to prevent red soil acidification and improve soil quality, and are found to be promising remediation materials for mitigating the risks posed by Cd-contaminated red soil.

Methylmercury (MeHg) in sediment is difficult to be determined due to its low concentration and binding compounds like sulfide and organic matter. Moreover, wet sediment samples have been suggested to behave differently from certified reference materials in MeHg analysis. Optimal pretreatment procedure for MeHg determination in sediments has not been ascertained and whether the procedure could apply to sediment samples with complex matrix merits further research. This work firstly compared recovery results of five pretreatment procedures for MeHg determination using ERM-CC580. Using the optimal pretreatment procedure, recovery results were analyzed in different sediment samples after manipulation of moisture content, organic matter, and acid volatile sulfide. The procedure using CuSO₄/HNO₃ as leaching solutions and mechanical shaking as extraction method was proved to produce the most satisfactory recovery results (100.67 ± 6.75%, mean ± standard deviation). And when moisture content varied from 20 to 80%, average recovery results in sediment samples ranged from 100 to 125%. Furthermore, before and after the manipulation of organic matter or acid volatile sulfide, spiking recovery results varied little and were all within acceptable limit (85~105%). Therefore, the procedure of CuSO₄/HNO₃-mechanical is proposed as a universal pretreatment method for MeHg determination in sediment samples with various characteristics.

The main aims of the present research were (1) investigation of the temporal trends of atmospheric benzene concentrations in Tehran city during the period 2010 to 2013 and (2) assessment of carcinogenic and non-carcinogenic health risks of inhalation exposure to benzene. For the first objective, the data of ambient air benzene concentrations were derived from 15 air quality monitoring stations (AQMSs) in Tehran during the years 2010 to 2013 and they were temporally investigated after data cleaning and missing data imputation. The excess lifetime cancer risk (ELCR) and hazard quotient (HQ) were estimated to reveal the carcinogenic and non-carcinogenic health effects of exposure to ambient benzene. Our findings indicated that over 2010–2013, annual mean concentrations of benzene were in the range of 1.84 to 2.57 μg m⁻³, and the highest annual mean concentration was observed in 2011 with a mean of 2.57 μg m⁻³. The four-year average concentration of benzene during the period from 2010 to 2013 was 2.14 μg m⁻³. Furthermore, the HQ for inhalation exposure to ambient benzene was lower than the acceptable risk level (HQ < 1) over the study time period which indicated that the non-carcinogenic effects are very unlikely to happen. In addition, health risk assessment for ELCR showed that the potential cancer risk for inhalation exposure to benzene was 1.67 × 10⁻⁵ over the study period, which is significantly higher than the limits recommended by the U.S. EPA (1 × 10⁻⁶). Our study clearly proves that the ambient benzene concentration in Tehran has substantially higher carcinogenic effects on the population. Appropriate sustainable control measures should be taken to reduce air benzene concentration and protect public health.

Biological reduction is an effective method for removal of perchlorate (ClO₄⁻), where perchlorate is transformed into chloride by perchlorate-reducing bacteria (PRB). An external electron donor is required for autotrophic and heterotrophic reduction of perchlorate. Therefore, plenty of suitable electron donors including organic (e.g., acetate, ethanol, carbohydrate, glycerol, methane) and inorganic (e.g., hydrogen, zero-valent iron, element sulfur, anthrahydroquinone) as well as the cathode have been used in biological reduction of perchlorate. This paper reviews the application of various electron donors in biological perchlorate reduction and their influences on treatment efficiency of perchlorate and biological activity of PRB. We discussed the criteria for selection of appropriate electron donor to provide a flexible strategy of electron donor choice for the bioremediation of perchlorate-contaminated water.

Rapid detection of oil released from underground storage tanks and estimation of its flow rate allows for the prevention of further contamination or the limitation of the spread of contaminants. In this research, we developed a method for oil release detection by sensing volumetric water contents (VWC) in a hydraulic control system. Oil release detection tests were conducted at bench and pilot scales. In the bench-scale test, oil and water were released directly on top of the oil release detection system. In the pilot-scale test, the release detection system was installed in the soil and the oil was spilled on the soil surface. The new oil release monitoring system was capable of detecting the oil release using the VWC decrease (0.42 → 0.11 m³/m³). The infiltration of water did not affect the value of VWC. Sequential injection or mixture of oil and water also showed a decrease in VWC (0.42 → 0.12 m³/m³). The rate of VWC decrease was directly proportional (− 0.003 ml/min) to the rate of oil infiltration. A conceptual model was suggested to delineate the mechanism of oil release detection and to estimate the rate of oil infiltration. The detectability of the oil release in soil was also verified in the pilot-scale test (0.45 → 0.12 m³/m³). The rate of oil infiltration could be estimated using the slope of the measured VWC. The amount of time for oil infiltration through the soil and dispersion during the migration should be considered to analyze the VWC curve properly. These results showed that the oil release detection system can be used to monitor oil release and to determine the rate of oil infiltration by installation in the soil near an underground storage tank.

Despite the controversy, the ecological risk of microplastics research has increased sharply from only one in 1966 to 495 in 2018, according to Web of Science with microplastics as keyword. To date, an upward trend of global microplastics mass emission was confirmed by many environmental scientists. The ocean is the ultimate destination of land-based microplastics sources; therefore, most of efforts were concentrated on microplastics in aquatic environment. In this brief article, the global release of microplastics and flux into the ocean in the recent decade were estimated roughly. The plastics fragmentation in the marine environment only accounted for 22% of total microplastics release (assuming defined emission rate per capita and fragmentation rate of plastics). Future research is needed for microplastics generation and retention in the terrestrial system, especially indoor environments. The accumulated microplastics over the environmental self-purification capacity certainly increases stress for the marine, freshwater and terrestrial ecosystem.