The inherent oxidation potential (OP) of atmospheric particulate matter has been shown to be an important metric in assessing the biological activity of inhaled particulate matter and is associated with the composition of PM₂.₅. The current study examined the chemical composition of 388 personal PM₂.₅ samples collected from students and guards living in urban and suburban areas of Beijing, and assessed the ability to predict OP from the calculated metrics of carcinogenic risk, represented by ELCR (excess lifetime cancer risk), non-carcinogenic risk represented by HI (hazard index), and the composition and sources of the particulate matter using multiple linear regression methods. The correlations between calculated ELCR and HI and the measured OP were 0.37 and 0.7, respectively. HI was a better predictor of OP than ELCR. The prediction models based on pollutants (Model_1) and pollution sources (Model_2) were constructed by multiple linear regression method, and Pearson correlation coefficients between the predicted results of Model_1 and Model_2 with the measured volume normalized OP are 0.81 and 0.80, showing good prediction ability. Previous investigations in Europe and North America have developed location-specific relationships between the chemical composition of particulate matter and OP using regression methods. We also examined the ability of relationships between OP and composition, sources, developed in Europe and North America, to predict the OP of particulate matter in Beijing from the composition and sources determined in Beijing. The relationships developed in Europe and North America provided good predictive ability in Beijing and it suggests that these relationships can be used to predict OP from the chemical composition measured in other regions of the world.

Cadmium (Cd) contamination in paddy soil often results in elevated Cd concentrations in rice grain, which is a serious concern threatening food safety. Most of the Cd accumulated in rice grain is derived from its remobilization in paddy soil during the grain filling period when paddy water is drained. We have previously shown that the voltaic cell effect controls the oxidative release of cadmium sulfide (CdS) during the drainage period. Metal sulfides with lower electrochemical potentials than CdS can suppress the oxidation of CdS. In the present study, we tested whether amendments of ZnSO₄ or MnSO₄ could enhance the suppressive voltaic effect on Cd release and subsequent accumulation in rice grain. The one-time addition of ZnSO₄ (75 kg/ha Zn) decreased CaCl₂-extractable Cd concentrations in soils by 32–64% in pot experiments and by 16–30% in field trials during the drainage period. Consequently, Cd concentrations in brown rice were reduced by 74–87% and 60–72% in pot experiments and field trials, respectively. Importantly, this effect persisted in the second year without further addition. The amendment of MnSO₄ had similar effects in decreasing soil extractable Cd and Cd concentrations in brown rice. These effects were not attributed to the addition of sulfate. A single application of such doses of ZnSO₄ or MnSO₄ (e.g. 75–150 kg/ha Zn or Mn) only caused a marginal increase in soil Zn or Mn concentrations and had no significant impact on grain yield. Taken together, amendments of ZnSO₄ and/or MnSO₄ (at the rate of 75–150 kg/ha Zn and or Mn) formed a protective voltaic cell partner against the oxidative dissolution of CdS and thus were highly effective in reducing Cd accumulation in rice grain. This work provides a simple but effective method to decrease soil Cd availability during soil drainage and mitigate Cd accumulation in rice to ensure food safety.

Standard monitoring programs give limited insight into groundwater status, especially transformation products (TPs) formed by natural processes or advanced oxidation processes (AOP), are normally underrepresented. In this study, using suspect and non-target screening, we performed a comprehensive analysis of groundwater before and after AOP by UV/H₂O₂ and consecutively installed biological activated carbon filters (BAC). By non-target screening, up to 413 compounds were detected in the groundwater, with an average 70% removal by AOP. However, a similar number of compounds were formed during the process, shown in groundwater from three waterworks. The most polar compounds were typically the most stable during the AOP. A subsequent BAC filter showed removal of 95% of the TPs, but only 46% removal of the AOP remaining precursors. The BAC removal for polar compounds was highly dependent on the acidic and basic functional groups of the molecules. 49 compounds of a wide polarity range could be identified by supercritical fluid chromatography (SFC) and liquid chromatography (LC) with high resolution mass spectrometry (HRMS); of these, 29 compounds were already present in the groundwater. To the best of our knowledge, five compounds have never been reported before in groundwater (4-chlorobenzenesulfonic acid, dibutylamine, N-phenlybenzenesulfonamide, 2-(methylthio)benzothiazole and benzothiazole-2-sulfonate). A further five rarely reported compounds are reported for the first time in Danish groundwater (2,4,6-trichlorophenol, 2,5-dichlorobenzenesulfonic acid, trifluormethansulfonic acid, pyrimidinol and benzymethylamine). Twenty of the identified compounds were formed by AOP, of which 10 have never been reported before in groundwater. All detected compounds could be related to agricultural and industrial products as well as artificial sweeteners. Whereas dechlorination was a common AOP degradation pathway for chlorophenols, the (ultra-) short chain PFAs showed no removal in our study. We prioritized 11 compounds as of concern, however, the toxicity for many compounds remains unknown, especially for the TPs.

Quinone is the important redox functional group for electron transfer capacity (ETC) of humic acid (HA). Lignin, as major component in corn straw, can be decomposed into phenol monomers, then oxidation into quinones for synthesis of HA during composting process. However, it is still unclear that the effects of type and variation characteristics of phenol monomers on redox characteristics of HA during straw composting process. In this study, p-hydroxybenzoic acid (P1), vanillic acid (P2), syringic acid (P3), p-hydroxy benzaldehyde (P4), 4-coumaric acid (P5), 4-hydroxyacetophenone (P6), ferulic acid (P7) and 4-hydroxy-3-methylacetophenone (P8) were recognized and clustered into three groups. The concentration of polyphenol presented a significant downward trend during the straw composting process. Based on the relationships among phenol monomers to ETC, electron donating capacity (EDC), electron accepting capacity (EAC) and quinone, we found that P1, P2, P3, P5 and P7 were significantly related to ETC, EDC and EAC of HA (P < 0.05). Furthermore, NH₄⁺-N and NO₃⁻-N were the main micro-environmental factors linking to ETC-related phenol monomers and redox characteristics of HA in straw composts (P < 0.05). Finally, two groups of core microflora that promoting the ETC-related phenol monomers and NH₄⁺-N, and ETC-related phenol monomers and NO₃⁻-N were identified by Mantel test, respectively. This study contributes a new insight for polyphenol way for redox capacity of HA in traditional composting and utilization of straw compost in contaminated environments.

Using the Spectral characteristics of gold nanorods to investigate heavy metals Pb in agricultural soils. Studied included: (1) The effects of humic acid on Pb transformation and its formation changing were explored. The laboratory model was established to simulate Pb leaching process in the soil and investigated the change of total Pb content at different layers. (2) The migration and transformation of different forms Pb were studied by the nano system. The effect of humic acid and pH were analyzed based on the nano-analysis method. (3) The relationship between various forms Pb irons were analyzed. (4) The data showed that ion exchange state and iron-manganese oxidation state Pb were more likely to enriched at 0 cm depth, and organic bound state was more likely to enriched at 10 cm depth. Humic acid increased the solidify ability of different forms of Pb in agricultural soil, and the analysis system was efficient to supply the exactly transition process.

Uranium, a radionuclide, is a predominant element utilized for speciality requirements in industrial applications, as fuels and catalyst. The radioactive properties and chemical toxicity of uranium causes a major threat to the ecosystem. The hazards associated with Uranium pollution includes the cancer in bones, liver, and lungs. The toxicological properties of Uranium are discussed in detail. Although there are many methods to eliminate those hazards, this research work is aimed to describe the application of bioremediation methods. Bioremediation methods involve elimination of the hazards of uranium, by transforming into low oxidation form using natural microbes and plants. This study deeply elucidates the methods as bioleaching, biosorption, bioreduction and phytoremediation. Bioleaching process involves bio-oxidation of tetravalent uranium when it gets in contact with acidophilic metal bacterial complex to obtain leach liquor. In biosorption, chitin/chitosan derived sorbents act as chelators and binds with uranium by electrostatic attraction. Bio reduction employs a bacterial transformation into enzymes which immobilize and reduce uranium. Phytoremediation includes phytoextraction and phytotranslocation of uranium through xylems from soil to roots and shoots of plants. The highest uranium removal and uptake reported using the different methods are listed as follows: bioleaching (100% uranium recovery), biosorption (167 g kg⁻¹ uranium uptake), bioreduction (98.9% uranium recovery), and phytoremediation (49,639 mg kg⁻¹ uranium uptake). Among all the techniques mentioned above, bioleaching has been proved to be the most efficient for uranium remediation.

PM₂.₅ (particulate matter having aerodynamic diameter ≤2.5 μm) samples were collected during wintertime from two polluted urban sites (Allahabad and Kanpur) in the central Indo-Gangetic Plain (IGP) to comprehend the sources and atmospheric transformations of light-absorbing water-soluble organic aerosol (WSOA). The aqueous extract of each filter was atomized and analyzed in a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). Water-soluble organic carbon (WSOC) and WSOA concentrations at Kanpur were ∼1.2 and ∼1.5 times higher than that at Allahabad. The fractions of WSOC and secondary organic carbon (SOC) to total organic carbon (OC) were also significantly higher ∼53% and 38%, respectively at Kanpur compared to Allahabad. This indicates a higher abundance of oxidized WSOA at Kanpur. The absorption coefficient (bₐbₛ₋₃₆₅) of light-absorbing WSOA measured at 365 nm was 46.5 ± 15.5 Mm⁻¹ and 73.2 ± 21.6 Mm⁻¹ in Allahabad and Kanpur, respectively, indicating the dominance of more light-absorbing fractions in WSOC at Kanpur. The absorption properties such as mass absorption efficiency (MAE₃₆₅) and imaginary component of refractive index (kₐbₛ₋₃₆₅) at 365 nm at Kanpur were also comparatively higher than Allahabad. The absorption forcing efficiency (Abs SFE; indicates warming effect) of WSOA at Kanpur was ∼1.4 times higher than Allahabad. Enhancement in light absorption capacity was observed with the increase in f44/f43 (fraction of m/z 44 (f44) to 43 (f43) in organic mass spectra) and O/C (oxygen to carbon) ratio of WSOA at Kanpur while no such trend was observed for the Allahabad site. Moreover, the correlation between carbon fractions and light absorption properties suggested the influence of low-volatile organic compounds (OC3 + OC4 fraction obtained from thermal/optical carbon analyzer) in increasing the light absorption capacity of WSOA in Kanpur.

Biochemical oxidation and reduction are key processes in treating biological wastewater and they require the presence of electron acceptors. The functional impact of electron acceptors on microbiomes provides strategies for improving the treatment efficiency. This research focused on two of the most important electron acceptors, nitrate and oxygen. Molecule ecological network, null model, and functional prediction based on high-throughput sequencing were used to analyze the microbiomes features and assembly mechanism. The results revealed nitrate via the homogeneous selection (74.0%) decreased species diversity, while oxygen via the homogeneous selection (51.1%) and dispersal limitation (29.6%) increased the complexity of community structure. Microbes that were more strongly homogeneously selected for assembly included polyphosphate accumulating organisms (PAOs), such as Pseudomonas and variovorax in the nitrate impacted community; Pseudomonas, Candidatus_Accumulibacter, Thermomonas and Dechloromonas, in the oxygen impacted community. Nitrate simplified species interaction and increased the abundance of functional genes involving in tricarboxylic acid cycle (TCA cycle), electron transfer, nitrogen metabolism, and membrane transport. These findings contribute to our knowledge of assembly process and interactions among microorganisms and lay a theoretical basis for future microbial regulation strategies in wastewater treatment.

The weathering and contaminant transport behavior of both primary (PMPs) and secondary microplastics (SMPs) are interrelated to their original physiochemical features and variations within the environment. This study examines the influence of PMPs' intrinsic characteristics (polymer structure and crystallinity) and SMPs' extrinsic features (surface oxidation and external sediments attachment) on the photodegradation kinetics, and subsequently Pb(II) and Zn(II) uptake from stormwater. For this purpose, high density polyethylene (HDPE) and low density polyethylene (LDPE) with different degrees of crystallinities were produced as PMPs, and their photodegradation behaviors were compared with original polymers. Furthermore, the SMPs generated by abrasion and surface oxidation of PMPs and the virgin PMPs underwent accelerated photodegradation, and the changes of their crystallinity, surface chemistry, and morphology were examined. Scanning electron microscopy (SEM) imaging and X-ray photoelectron (XPS) studies revealed the formation of cracks and different oxidized functionalities on MPs surface due to UV photodegradation. The vinyl and carbonyl indices calculated using Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) spectroscopy demonstrated an elevated photodegradation rate for SMPs compared to the PMPs. Moreover, the Differential Scanning Colorimetry (DSC) demonstrated an increasing percentage of crystallinity in all MPs due to the photodegradation. The percent crystallinity of HDPE pellets increased after photodegradation from 49.8 to 62.6 and it increased from 17.2 to 38.9 for LDPE pellets respectively. The greater level of increase in crystallinity for LDPE in comparison to HDPE upon photodegradation was referred to as LDPE's greater amorphous content and branched structure. A greater level of metal uptake was obtained for photodegraded LDPE pellets as 2526 μg/m² for Pb(II) and 2028 μg/m² for Zn(II) respectively.

Electric and magnetic fields characterized by high efficiency, low consumption and environment-friendly performance have recently generated interest as a possible measure to enhance the performance of the biological treatment process used to remove refractory organics. Few studies have been carried out to-date regarding the simultaneous application of electric and magnetic fields on biofilm process to degrade diclofenac. In this study, 3DEM-BAF was designed to evaluate the electrio-magnetic superposition effect on diclofenac removal performance, kinetics, community structure and synergistic mechanism. The results show that 3DEM-BAF could significantly increase the average removal rate of diclofenac by 65.30 %, 57.46 %, 9.48 % as compared with that of BAF, 3DM-BAF, 3DE-BAF, respectively. The diclofenac degradation kinetic constants and dehydrogenase activity of 3DEM-BAF were almost 6.72 and 2.53 times higher than those of BAF. Microorganisms of 3DEM-BAF in the Methylophilus and Methyloversatilis genera were distinctively enriched, which was attributed to the screening function of electric field and propagation effect of magnetic field. Moreover, three processes were found to contribute to diclofenac degradation, namely electro-magnetic-adsorption, electro-chemical oxidation and electro-magnetic-biodegradation. Thus, the simultaneous application of electric and magnetic fields on biofilm process was demonstrated to be a promising technique as well as a viable alternative in diclofenac degradation enhancement.