Contamination levels and ecological risk assessment of phthalate esters (PAEs) in the aquatic environment of Chaohu Lake.

Phthalate esters (PAEs), widely recognized as synthetic organic compounds with extensive production and utilization, are known to disrupt physiological processes in both animals and humans, even at low environmental concentrations. This study investigated the occurrence, distribution, and potential ecological risk of five representative PAEs (DMP, Dimethyl phthalate; DEP, Diethyl phthalate; DBP, Dibutyl phthalate; DiBP, Diisobutyl phthalate; DEHP, Bis(2-ethylhexyl) phthalate) in a typical lake (Chaohu Lake, China). It was found that PAEs were detected in both the aqueous (1.09-6.402 µg/L) and solid phases (0.827-6.602 µg/g) of Chaohu Lake. Notably, DiBP and DBP were the predominant PAEs in the water, and DiBP and DEHP were the most prevalent in the sediments. The concentrations of PAEs exhibited significant seasonal variations in the aqueous phases, with total PAEs in summer being nearly twice those in winter. Toxicity assessments revealed that DEHP, DBP, and DiBP posed high risks to the survival of three indicator organisms (algae, Daphnia, and fish) in the aqueous phase. In the solid phase, the exceeding rate of DiBP was as high as 92.9%. On the other hand, DBP and DEHP generally presenting moderate risk, although some sites were identified as high-risk. This study's analysis of PAEs concentrations in Chaohu Lake reveals a discernible increasing trend when compared with historical data. These findings underscore the urgent need for interventions to mitigate the ecological threats posed by PAEs in Chaohu Lake.

Variations in the concentration, inventory, source, and ecological risk of polycyclic aromatic hydrocarbons in sediments of the Lake Chaohu.

In this study, the ecological risk assessment of PAHs pollution, the existing S-T model was improved and applied to this PAHs pollution assessment in surface sediment in Lake Chaohu. The potential sources and contributions of PAHs in the surface sediment were estimated by molecular diagnostic ratio (MDR) and positive matrix factorization (PMF). The results showed that the average concentration of 16 priority PAHs in the surface sediment was 718.16 ng/g in 2009 and 334.67 ng/g in 2020. In 2020, PAHs concentration has decreased compared to 2009 and the dominant composition has changed from high- to low-molecular-weight PAHs. The estimated PAHs mass inventory of the top 2 cm surface sediment was 2712 tons in 2009 and 1263 tons in 2020. Ecosystem risk assessment by improved S-T models suggested that the overall ecosystem risk of the studied regions was acceptable.

Simultaneous adsorption of Cd(II) and degradation of OTC by activated biochar with ferrate: Efficiency and mechanism.

Biochar-supported zero-valent iron nanocomposites have received much attention due to their application potential in environmental pollution remediation. However, in many occasions, zero-valent iron loading improves the electron transfer efficiency and catalytic oxidation capacity of biochar while blocking the original pore structure of biochar, limiting its application potential. In this study, a zero-valent iron composites with large SSA (865.86 m2/g) was prepared in one step using pre-pyrolysis of biochar powder and K2FeO4 grinding for co-pyrolysis. The processes of ZVI generation and SSA expansion during the pyrolysis were investigated. The factors affecting the removal process of Cd and OTC in water by the composites were investigated. The mechanisms of Cd fixation and OTC degradation by the composites were explored by experiments, characterization, and DFT calculations. The OTC degradation pathway was proposed by theoretical predication and LC-MS spectrometry. The results indicate that ion exchange, complexation with oxygen-containing functional groups, electrostatic attraction, and interaction with π-electrons are the main mechanisms of Cd immobilization. The degradation pathways of OTC mainly include dehydroxylation, deamination and dealkylation.

Recycling chestnut shell for superior peroxymonosulfate activation in contaminants degradation via the synergistic radical/non-radical mechanisms.

The efficient recycling of agricultural chestnut shell waste is of considerable interest due to its large availability and economic feasibility. Herein, an alkaline-activated biochar was thermally prepared using chestnut shell by finely regulating main conditions; its morphological, structural and physic-chemical properties were well characterized. Fenton-like capacity to trigger peroxymonosulfate activation for superior pollutant degradation with high efficiency and good selectivity was validated in different water matrix. Both radical formation and electron transfer were identified as reaction pathways, while the selective non-radical mechanism played the major role in pollutant degradation. Surface ketonic groups were identified as the main reactive sites for non-selective radical production, while crystal edges and structural defects on sp2/sp3 carbon network could smoothly mediate the selective electron transfer from pollutant to oxidant in the non-radical Fenton-like catalysis. The two-mixed radical/non-radical pathways exhibited important advantages for environmental decontamination, in comparison with the one-single radical or non-radical mechanism. Our study provided a promising recycling strategy for agricultural chestnut shell, as well as an environment-friendly catalyst for heterogeneous Fenton-like catalysis in green water purification rendered by the synergistic radical/non-radical reaction pathways.

Study of the denitration performance of a ceramic filter using a manganese-based catalyst.

A MnO x /γ-Al2O3 catalyst was prepared by impregnation of manganese acetate and alumina. After optimizing the composition, it was loaded into a ceramic filter (CF) by a one-step coating method. The results show that MnO x /γ-Al2O3 had the best denitration activity when the Mn loading was 4 wt% with a calcination temperature of 400 °C. The MnO x /γ-Al2O3 catalyst ceramic filter (MA-CCF) was made by loading the CF twice with MnO x /γ-Al2O3. When face velocity (FV) was 1 m min-1, MA-CCF displayed more than 80% NO conversion at 125-375 °C and possessed a good resistance of H2O and SO2. The abundant surface adsorbed oxygen, dense membrane and high-density fiber structure on the outer layer of CF effectively protected the catalyst and could improve MA-CCF denitration activity. The multiple advantages of MA-CCF made it possible for good application prospects.

Removal of oxytetracycline promoted by manganese-doped biochar based on density functional theory calculations: Comprehensive evaluation of the effect of transition metal doping.

The regulation of surface electrons by non-metal doping of biochar (BC) is environmentally and ecologically significant. However, systematic studies on the regulation of surface electrons by transition metal doping are lacking. The present study is based on the observation that the removal efficiency of oxytetracycline (OTC) by Mn-doped BC is eight times higher than that of undoped BC in 20 min. The effects of Mn doping on the crystal phase formation, persistent free radicals (PFRs), electron density, molecular orbitals, and nucleophilic active sites of BC are investigated, and the intermediate products of OTC are evaluated. Mn doping enhances the signal for sp2-hybridised carbon-carbon double bond, forms more delocalised π-bonds, and promotes the formation of free radicals centred on the carbon atoms. The specific surface area of BC increases, and manganese oxide is formed on the its surface. Density functional theory calculations show that Mn doping accelerates the electron transfer of BC, provides additional electrons for the BC system, and makes this system more ionised. OTC molecules preferentially attack the nucleophilic reaction sites near Mn atoms based on molecular electrostatic potential measurements. Therefore, this study provides new insights into the surface electronic structures regulated by transition metal elements.

Synthesis of Calcium Silicate Hydrate from Coal Gangue for Cr(VI) and Cu(II) Removal from Aqueous Solution.

Both the accumulation of coal gangue and potentially toxic elements in aqueous solution have caused biological damage to the surrounding ecosystem of the Huainan coal mining field. In this study, coal gangue was used to synthesize calcium silicate hydrate (C-S-H) to remove Cr(VI) and Cu(II)from aqueous solutions and aqueous solution. The optimum parameters for C-S-H synthesis were 700 °C for 1 h and a Ca/Si molar ratio of 1.0. Quantitative sorption analysis was done at variable temperature, C-S-H dosages, solution pH, initial concentrations of metals, and reaction time. The solution pH was precisely controlled by a pH meter. The adsorption temperature was controlled by a thermostatic gas bath oscillator. The error of solution temperature was controlled at ± 0.3, compared with the adsorption temperature. For Cr(VI) and Cu(II), the optimum initial concentration, temperature, and reaction time were 200 mg/L, 40 °C and 90 min, pH 2 and 0.1 g C-S-H for Cr(VI), pH 6 and 0.07 g C-S-H for Cu(II), respectively. The maximum adsorption capacities of Cr(VI) and Cu(II) were 68.03 and 70.42 mg·g-1, respectively. Furthermore, the concentrations of Cu(II) and Cr(VI) in aqueous solution could meet the surface water quality standards in China. The adsorption mechanism of Cu(II) and Cr(VI) onto C-S-H were reduction, electrostatic interaction, chelation interaction, and surface complexation. It was found that C-S-H is an environmentally friendly adsorbent for effective removal of metals from aqueous solution through different mechanisms.

Anaerobic co-digestion of landfill leachate and acid mine drainage using up-flow anaerobic sludge blanket reactor.

A laboratory-scale up-flow anaerobic sludge blanket (UASB) reactor was developed and constructed for the treatment of landfill leachate and acid mine drainage (AMD). The removal of chemical oxygen demand (COD), sulfate, and metal ions was studied. The maximum COD and sulfate removal efficiency reached 75% and 69%, respectively, during the start-up phase of the UASB. The hydraulic retention time (HRT) had a significant influence on the system. The maximum removal efficiency for COD and sulfate reached 83% and 78%, respectively, at an HRT of 20 h. The methane production process competed with the sulfate reduction process in the UASB. The fractionation of metals in the sludge was analyzed to facilitate metal recovery in a later processing stage. The most abundant sulfate-reducing bacteria was Desulfobulbus, and the methanogen archaeal community in the reactor was mainly composed of Methanobacterium.

Heavy metals in face paints: Assessment of the health risks to Chinese opera actors.

The actors in Chinese operas are exposed to heavy metals through the face paints that they use but the resulting health risks are unknown. We therefore conducted a survey of face paint use by Chinese opera actors and then assayed 91 paint samples of various paint brands and colors for their contents of eight heavy metals. The potential health risks of heavy metal exposure due to face paint use were determined as well. The average concentrations of As, Cd, Co, Cr, Cu, Ni, Pb, and Zn were 1.8, 0.6, 4.4, 23.1, 610, 7.6, 16.2, and 10,415 µg/g, respectively, and at least four of the eight elements were detected in all samples. Samples from the most frequently paint brands were the most highly contaminated, especially with Zn, whose mass contribution was extremely high (18.3%). Moreover, contamination of the paint was color-specific, with significantly higher heavy metal levels in brown (As, Cr, and Ni), black (Co and Zn), red (Pb), and green (Cu) paints. The total carcinogenic risk posed by the metals in 25 paint samples ranged between 0.01% and 0.96%, with the highest risk that of Cr. Thus, lifetime exposure to Cr-containing paints would result in a high probability of the actor developing cancer. The findings of our study highlight the need for Chinese regulations addressing the heavy metals in face paints, especially Cr. Capsule: Chinese opera actors have a high probability of developing cancer due to a lifetime exposure to high levels of heavy metals in their face paints.

Impact of goethite dosed continuous stirred tank reactor on continuous methane production at different organic loading rates.

Iron oxides facilitated anaerobic digestion process has been attracted more and more attention in the renewable energy production area. In the current study, goethite was added into the continuous stirred tank reactor with glucose as the substrate. Effect of the influent organic loading rate (OLR) on the reactor performances was explored. Results showed that goethite promoted the methane production significantly (p < 0.05) when OLR was changed between 1.20 and 1.80 g glucose L-1  day-1 . Compared to the control reactor, addition of goethite improved the methane production by13.4%-22.9%. The iron reduction rate had a positive correlation with the methane production rate. Microbial community analysis results showed that OLRs influenced the dominant methanogenic species in the both reactors. Methanothrix, Methanobacterium, Methanosarcina, and Methanocella were dominant under various OLR levels. PRACTITIONER POINTS: Goethite could promote the methanogenic process of glucose in the CSTRs under certain levels of OLRs. Iron reduction rate had a positive correlation with the methane production rate. OLRs influenced the dominant methanogenic species in the goethite-dosed reactors.

Multiplexed discrimination of microRNA single nucleotide variants through triplex molecular beacon sensors.

Herein, we develop a new nanopore sensing strategy for the selective detection of microRNAs and single nucleotide variants (SNVs) based on triplex molecular beacon sensors. This sensing system shows very high specificity in discriminating microRNA SNVs and can be applied for the simultaneous detection of several microRNAs of the same family in a mixture.

Photochemical transformation of dimethyl phthalate (DMP) with N(iii)(H2ONO+/HONO/NO2-) in the atmospheric aqueous environment.

The photochemical transformation of dimethyl phthalate (DMP) with N(iii)(NO2-/HONO/H2ONO+) was investigated using 365 nm steady-state irradiation and 355 nm laser flash photolysis (LFP) techniques. The results showed that N(iii) concentration, DMP initial concentration and pH values all strongly affected the oxidation efficiency of DMP. The primary step of the reaction was the attack of ˙OH radicals on the aromatic ring to form a DMP-OH adduct, and the bimolecular rate constant was determined to be (5.5 ± 0.4) × 109 M-1 s-1. The DMP-OH adduct not only underwent monomolecular self-decay with a rate constant of (1.6 ± 0.3) × 104 s-1 but also interacted with HONO, H2ONO+ and O2 with rate constants of (6.4 ± 0.4) × 106 M-1 s-1, (8.8 ± 0.5) × 106 M-1 s-1 and (1.6 ± 0.1) × 108 M-1 s-1, respectively. Major transformation products including methyl salicylate, monomethyl phthalate, dimethyl 4-hydroxyphthalate and dimethyl 4-nitrophthalate were identified by GC-MS and characteristics of these secondary contaminants required extra attention.

Kinetics analysis of interfacial electron-transfer processes in goethite suspensions systems.

The photochemical behavior of goethite has been one of the most important topics in the field of environmental science due to it plays a significant role in the removal and transformation process of numerous pollutants. However, the interfacial electron transfer process of goethite is not clear. Using a nanosecond laser flash photolysis spectrometer, we report the transient spectroscopic observations of interfacial electron-transfer reactions in goethite dispersion under UV irradiation. Excitation of goethite generated conduction-band electron (ecb-) and hole (h+). The conduction band electron (ecb-) reacted with an electron acceptor, methylviologen dichloride hydrate (MV2+), forming reduced methylviologen (MV+) with a second-order rate constant of (2.6 ± 0.3) × 109 L mol-1 s-1. The concentration of MV+ was strongly influenced by MV2+ initial concentration and pH values. The flat band potential of goethite was calculated to be Efb (goethite, pH = 7) = 0.24 V (vs NHE). Oxygen did not react with conduction band electron of goethite. The present study provides a reliable method to investigate the photo-induced interfacial charge transfer of goethite.

Identification and determination of the contribution of iron-steel manufacturing industry to sediment-associated polycyclic aromatic hydrocarbons (PAHs) in a large shallow lake of eastern China.

Seventeen polycyclic aromatic hydrocarbon (PAH) compounds were determined in surface sediments collected from the Chaohu Lake (a large shallow lake in eastern China) and its tributaries. Both diagnostic ratios and a receptor model (positive matrix factorization, PMF) were applied to identify and determine the contribution of a local iron-steel manufacturing plant located in the Nanfei River (NFR) to the Chaohu Lake basin. The results show that sites located in the downstream of the steel plant contained concentrations of 17 PAH (Σ17PAH) approximately two orders of magnitudes higher than those from other sites. Five factors were identified by the PMF model, including industrial waste, wood/biomass burning, diagenetic origin, domestic coal combustion, and industrial combustion. Our findings suggest that sediments in the downstream of the plant and in the western part of the Chaohu Lake were predominantly affected by industrial coal combustion. A mixture of pyrolytic origins impacted urban sediments in the upstream of the plant, whereas diagenetic origins along with coal and biomass burning were suggested to influence the eastern part and rural tributaries of the lake. To assess the potential ecological risk and toxicity caused by the iron-steel plant, sediment toxicity was evaluated by the PMF model, sediment quality guideline, and toxic equivalent factors. All of the three approaches suggested PAH accumulation in the NFR sediments could produce significant adverse ecological effects and half of the sediment toxicity in the NFR may be attributed to the emissions from the iron-steel plant. Some rural locations also exhibited PAH concentrations above probable effects, most likely contributed by wood/biomass burning.

Influence of Different Electron Acceptors on the Anaerobic Degradation of Curly-Leaf Pondweed.

Curly-leaf pondweed (Potamogeton crispus) was utilized as the representative to investigate the biodecomposition process of aquatic plants under different reducible conditions. Results showed that the methane production was inhibited when different electron acceptors (Fe(III), and ) were available. The methane production was decreased by 57% when Fe(III) and or were both available compared to the control. The degradation efficiency of hemicellulose and lignin with Fe(III) and were increased significantly. This provided a theoretical basis for slowing down the emissions of methane.

Occurrence, compositional distribution, and toxicity assessment of pyrethroid insecticides in sediments from the fluvial systems of Chaohu Lake, Eastern China.

Surface sediment-associated synthetic pyrethroid insecticides (SPs) are known to pose high risks to the benthic organisms in Chaohu Lake, a shallow lake of Eastern China. However, the pollution status of the lake's tributaries and estuaries is still unknown. The present study was conducted to investigate the occurrence, compositional distribution, and toxicity of 12 currently used SPs in the surface sediments from four important tributaries, as well as in the sediment cores at their estuaries, using GC-MS for quantification. All SPs selected were detectable, with cypermethrin, es/fenvalerate, and permethrin dominant in both surface and core sediments, suggesting that these compounds were extensively applied. Urban samples contained the highest summed concentrations of the 12 SPs analyzed (Σ12SP) in both surface and core sediments compared with rural samples, suggesting that urban areas near aquatic environments posed high risks for SPs. The mean concentration of Σ12SP in surface sediments of each river was generally higher than that found in core sediments from its corresponding estuary, perhaps implying recent increases in SP usage. Surface sediments were significantly dominated by cypermethrin and permethrin, whereas core sediments were dominated by permethrin and es/fenvalerate. The compositional distributions demonstrated a spatial variation for surface sediments because urban sediments generally contained greater percentages of permethrin and cypermethrin, but rural sediments had significant levels of es/fenvalerate and cypermethrin. In all sediment cores, the percentage of permethrin gradually increased, whereas es/fenvalerate tended to decrease, from the bottom sediments to the top, indicating that the former represented fresh input, whereas the latter represented historical residue. Most urban samples would be expected to be highly toxic to benthic organisms due to the residue of SPs based on a calculation of toxic units (TUs) using toxicity data of the amphipod Hyalella azteca. However, low TU values were found for the samples from rural areas. These results indicate that the bottom sediments were exposed to high risk largely by the residual SPs from urban areas. The summed TUs were mostly attributable to cypermethrin, followed by λ-cyhalothrin and es/fenvalerate. Despite permethrin contributing ∼28.7 % of the Σ12SP concentration, it only represented 6.34 % of the summed TUs. Therefore, our results suggest that high levels of urbanization can increase the accumulation of SPs in aquatic environments.

Occurrence, source identification and ecological risk evaluation of metal elements in surface sediment: toward a comprehensive understanding of heavy metal pollution in Chaohu Lake, Eastern China.

In the present study, surface sediment samples from 48 sites covering the whole water area and three main estuaries of Chaohu Lake were collected to determine the concentrations of 25 metal elements using microwave-assisted digestion combined with ICP-MS. Spatial variation, source appointments, and contamination evaluation were examined using multivariate statistical techniques and pollution indices. The results show that for the elements Cd, Pb, Zr, Hf, U, Sr, Zn, Th, Rb, Sn, Cs, Tl, Bi, and Ba, which had higher coefficients of variation (CV), the concentrations were significantly higher in the eastern lake than in the western lake, but other elements with low CV values did not show spatial differences. The accumulation of Cu, Zn, Rb, Sr, Zr, Cd, Sn, Cs, Ba, Hf, Ta, Tl, Pb, Bi, U, and Th in the surface sediments was inferred as long-term agricultural cultivation impact, but that of Ti, V, Cr, Mn, Co, and Ni may have been a natural occurrence. The contribution from industrial and municipal impact was negligible, despite the rapid urbanization around the studied area. Principal component analysis-multiple linear regression (PCA-MLR) predicted the contribution from agricultural activities to range from 0.45 ± 1.31% for Co to 92.7 ± 17.7% for Cd. The results of the pollution indices indicate that Chaohu Lake was weakly to moderately affected by Ti, V, Cr, Mn, Co, and Ni but was severely contaminated by Hf and Cd. The overall pollution level in the eastern lake was higher than that in the western lake with respect to the pollution level index (PLI). Therefore, our results can help comprehensively understand the sediment contamination by metals in Chaohu Lake.

[Modeling the Environmental Behaviors and Ecological Risks of Permethrin in Chaohu Lake].

Environmental pollution caused by synthetic pyrethroid insecticides has received a great deal of attention with the increase in usage recently.To understand the occurrence, environmental processes, fate and ecological impact of permethrin in Chaohu Lake, fugacity based multimedia fate model combining species sensitivities model (SSD) were employed.The concentration distribution, and transfer fluxes were predicted under nonequilibrium steady-state condition, and the effect of input parameter on the outputs was evaluated by sensitive and uncertainty analysis.Furthermore, SSD model of aquatic organisms was constructed for permethrin to assess the potential ecological risk and to determine the maximum annual input amount of permethrin for the purpose of protecting 95% of species.The results showed that the predicted concentrations of permethrin in air, water and sediment were 3.99×10-16, 5.63×10-11, 1.95×10-5mol·m-3, and sediment was the largest sink.Most permethrin was transported from water to air via volatilization, but elimination from air was mostly by particle dry deposition.Permethrin in water was predominately from advection, and was removed by deposition of suspended particulate matter.Sediment associated permethrin was generally derived from suspended particulate matter deposition, and was eliminated by resuspension and sediment burial.The results of SSD model suggested HC5 value was at 0.97 ng·L-1, which was much higher than the predicted environmental concentration of permethrin in water.Only 0.77% of species was possibly impacted by exposure to permethrin.In order to protect 95% of species in Chaohu Lake, the maximum annual input amount of permethrin should be controlled below 78.2 t·a-1.

[Screening of epoxy-degrading halophiles and their application in high-salt wastewater treatment].

In this study, two halophilic bacteria were isolated from activated sludge in the epoxy wastewater treatment system. The strains were identified, and the growth and degradation characteristics were investigated. Strain J1 and J2 was identified respectively by morphological observation and 16S rDNA sequence alignment analysis. It was found that both strains belong to the Bacillus genus (Bacillus sp.) and branch Bacillus (Virgibacillus sp.). The optimized growth condition of strain J1 and J2 in the high salt CM culture medium was as follows: solution temperature 30 degrees C, pH 7.0 and 5-50 g x L(-1) of NaCl. Furthermore, the best degradation condition of the organic epoxy wastewater was: temperature 30 degrees C, pH 7.0 and NaCl concentration 30 g x L(-1). When the volume ratio of bacterial suspension mixture of J1 and J2 was 2:1 and the inoculum size of the composite strains was 10%, the highest COD removal efficiency was achieved in the epoxy wastewater treatment.

Feasibility of anaerobic digested corn stover as biosorbent for heavy metal.

Anaerobic digested (AD) corn stover collected from a lab-scale reactor was used as bioadsorbent to remove the heavy metal in aqueous solution. Effects of contact time and initial heavy metal concentrations on the removal process of Cu(2+) and Cd(2+) were investigated. The maximum adsorption capacities of AD corn stover obtained from Langmuir isotherm models were 83.3 and 50.0mg/g for Cu(2+) and Cd(2+), respectively. Fourier transform infrared spectroscopy (FTIR) was also used to investigate the surface characteristic of raw and heavy metal loaded AD corn stover.