Metabolomics reveals how spinach plants reprogram metabolites to cope with intense stress responses induced by photoaged polystyrene nanoplastics (PSNPs).

While land-based sources have been recognized as significant long-term sinks for micro- and nanoplastics, there is limited knowledge about the uptake, translocation, and phytotoxicity of nanoplastics (NPs) in terrestrial environments, especially aged NPs. In this study, we investigated the impact of aged polystyrene nanoplastics (PSNPs) on the uptake, physiology, and metabolism of spinach. Our findings revealed that both pristine and aged PSNPs can accumulate in the roots and subsequently translocate to the aboveground tissues, thereby influencing numerous key growth indicators in spinach plants. A more pronounced impact was observed in the treatment of aged PSNPs, triggering more significant and extensive changes in metabolite levels. Furthermore, alterations in targeted pathways, specifically aminoacyl-tRNA biosynthesis and phenylpropanoid biosynthesis, were induced by aged PSNPs, while pristine PSNPs influenced pathways related to sulfur metabolism, biosynthesis of unsaturated fatty acids, and tryptophan metabolism. Additionally, tissue-specific responses were observed at the metabolomics level in both roots and leaves. These results highlight the existence of diverse and tissue-specific metabolic responses in spinach plants exposed to pristine and aged PSNPs, providing insights into the mechanisms of defense and detoxification against NP-induced stress.

Insight into interactions between microplastics and fulvic acid: Mechanisms affected by microplastics type.

Microplastics (MPs) can interact with dissolved organic matter (DOM), a common component found in the environment. However, the effect of MPs type on its interaction with DOM has not been systematically studied. Therefore, the binding properties of different MPs with fulvic acid (FA) were explored in this study. The results showed that polypropylene (PP) and polyethylene (PE) had higher adsorption affinity for FA than polystyrene (PS) and polyvinyl chloride (PVC). The interaction between MPs and FA conformed to the pseudo-first-order model and Freundlich model (except PS). The interaction mechanisms between various MPs tested in this paper and FA are considered to be different. PP, PE and PS interacted with the aromatic structure of FA and were entrapped in the FA polymers by the carboxyl groups and CO bonds, resulting in a highly conjugated co-polymer, suggesting that oxygen-containing functional groups played a key role. However, it was assumed that the interaction between PVC and FA was more likely to be caused by hydrophobic interaction. This research will help to enhance our comprehension of the environmental behavior of MPs and their interaction with the DOM specifically.

Bacterial community succession and the enrichment of antibiotic resistance genes on microplastics in an oyster farm.

Microplastics can be colonized by microorganisms and form plastisphere. However, knowledge of bacterial community succession and the enrichment of antibiotic resistance genes (ARGs) and pathogens on microplastics in aquaculture environments is limited. Here, we conducted a 30-day continuous exposure experiment at an oyster farm. Results showed that the alpha-diversity of communities on most microplastics continuously increased and was higher than in planktonic communities after 14 days. Microplastics could selectively enrich certain bacteria from water which can live a sessile lifestyle and promote colonization by other bacteria. The composition and function of plastisphere communities were distinct from those in the surrounding water and influenced by polymer type and exposure time. Microplastics can enrich ARGs (sul1, qnrS and blaTEM) and harbor potential pathogens (e.g., Pseudomonas aeruginosa). Therefore, microplastic pollution may pose a critical threat to aquaculture ecosystems and human health. Our study provides further insight into the ecological risks of microplastics.

Deterministic processes shape bacterial community assembly in a karst river across dry and wet seasons.

Karst rivers are particularly vulnerable to bacterial pollution because immigrations are easily diffused from the surrounding environments due to their strong hydraulic connectivity. However, the assembly mechanism in shaping riverine bacterial biogeography is still poorly understood, especially for an ecosystem in the karst area. Here, 16S rRNA genes were used to explore the spatiotemporal and biogeographical patterns of bacterial communities from the Chishui River in the dry and wet seasons, and explore the impact of external immigration on the assembly of water bacterial communities. Our results showed clear spatiotemporal patterns of bacterial communities with a more pronounced seasonal rather than spatial fluctuation, which appeared to be dependent on seasonal-related environmental factors (e.g., temperature and turbidity). The bacterial communities exhibited a significant (p < 0.05) distance-decay pattern in both seasons, and they had a stronger distance-decay relationship in the dry season than in the wet season. However, most of the biomarkers of different external immigrations did not show significant (p > 0.05) distance-decay patterns along the Chishui river, implying that the biomarkers could be used as indicators of external immigration (e.g., OTU_125 and OTU_536). Also, the tributaries were the main external immigration (20.44-83.68%) for the Chishui River, while other terrestrial immigration (e.g., livestock, the soil of the cropland, brewing wastewater treatment plant, and sewages) showed relatively little influence, which could be due to the hydrodynamic conditions (e.g., fragile rock-soil system and hydrological structure) of the karst river. Additionally, the assembly of water bacterial communities in the Chishui river was governed by more determinism (50.7-85.7%) than stochasticity (14.3-49.3%) in both the dry and wet seasons. We demonstrated that the bacterial community's substantial variations are largely shaped by deterministic processes, thereby providing a better understanding of spatiotemporal patterns and mechanisms of the bacterial community in karst river waters.

Different functional areas and human activities significantly affect the occurrence and characteristics of microplastics in soils of the Xi'an metropolitan area.

Microplastics (MPs) pollution in the environment has become a global hotspot, but there is insufficient research on MPs in soils of large cities. This study investigated the pollution status of MPs in soils in different functional areas (commercial, tourist, industrial, and residential areas) of the Xi'an metropolitan area. The average abundances of MPs were 2218 items/kg in Xi'an city, 1329 items/kg in Xianyang city and 1400 items/kg in Yangling city. All MPs presented different shapes and were dominated by fragment and fiber. The 0-0.5 mm MPs accounted for the largest proportion. Polyethylene terephthalate (PET) was the predominant polymer type for MPs. The results showed that the soil in the Xi'an metropolitan area was polluted by MPs, with the pollution of MPs in Xi'an city being more severe than other two cities. This could be related to the advanced urbanization and industrialization process. Moreover, industrial and tourist areas had frequent industrial and human activities, so their MPs pollution was the worst. In addition, residential areas and some commercial areas far away from pollution sources had lower pollution levels and a more uniform distribution of MPs. This study may provide data and valuable reference for the investigation of soil MPs pollution in the Xi'an metropolitan area.

Distribution and correlation between antibiotic resistance genes and host-associated markers before and after swine fever in the longjiang watershed.

Antibiotic resistance genes (ARGs) are abundantly shed in feces. Thus, it is crucial to identify their host sources so that ARG pollution can be effectively mitigated and aquatic ecosystems can be properly conserved. Here, spatiotemporal variations and sources of ARGs in the Longjiang watershed of South China were investigated by linking them with microbial source tracker (MST) indicators. The most frequently detected ARGs (>90%) were sulI, sulII, blaTEM, tetW, ermF, and the mobile element intI1. Spatial distribution analyses showed that tributaries contributed significantly more sulI, sulII, and ermF contamination to the Longjiang watershed than the main channel. MST indicator analysis revealed that the Longjiang watershed was contaminated mainly by human fecal pollution. Livestock- and poultry-associated fecal pollution significantly declined after the swine fever outbreak. The occurrence of most ARGs is largely explained by human fecal pollution. In contrast, pig fecal pollution might account for the prevalence of tetO. Moreover, combined human-pig fecal pollution contributed to the observed blaNDM-1 distribution in the Longjiang watershed. Subsequent analysis of the characteristics of MST markers disclosed that the relatively lower specificities of BacHum and Rum-2-Bac may lead to inaccurate results of tracking ARG pollution source. The present study determined spatiotemporal variations and ARG origins in the Longjiang watershed by combining MST markers. It also underscored the necessity of using multiple MST markers simultaneously to identify and characterize ARG pollution sources accurately.

Water quality prediction model using Gaussian process regression based on deep learning for carbon neutrality in papermaking wastewater treatment system.

Wastewater recycling is the measure with enormous potentiality to achieve carbon neutrality in wastewater treatment plants. High-precision online monitoring can improve the stability of wastewater treatment system and help wastewater recycling. A new water quality prediction CSWLSTM-GPR model, which fused the spatial feature of convolutional neural network (CNN), the temporal feature of sharing-weight long short-term memory (SWLSTM) and the probabilistic reliability of Gaussian process regression (GPR), was applied for monitoring papermaking wastewater treatment system with high-precision point prediction and interval prediction. Compared with SWLSTM-GPR and CLSTM-GPR, RMSE of CSWLSTM-GPR reduced by more than 48.9% on effluent chemical oxygen demand (CODeff), MAE reduced by more than 49.3%, R2 increased by more than 25.14%, R increased by more than 7.07%. And for the effluent suspended solids (SSeff), CSWLSTM-GPR had better predictive results than SWLSTM-GPR and CSWLSTM-GPR. Compared with SWLSTM-GPR, RMSE, MAE, R, R2 of CSWLSTM-GPR on effluent suspended solids (SSeff) were improved by 4.8%, 6.1%, 29.01% and 31.15%, respectively. Simulation results showed convincing comprehensive forecasting ability were obtained and the true values frequently stayed within the water quality range obtained by CSWLSTM-GPR model, which provided important insights for online monitoring, wastewater recycling and carbon neutrality of papermaking industry.

Magnetic biochars have lower adsorption but higher separation effectiveness for Cd2+ from aqueous solution compared to nonmagnetic biochars.

Magnetic biochars were prepared by chemical co-precipitation of Fe3+/Fe2+ onto rice straw (M-RSB) and sewage sludge (M-SSB), followed by pyrolysis treatment, which was also used to prepare the corresponding nonmagnetic biochars (RSB and SSB). The comparison of adsorption characteristics between magnetic and nonmagnetic biochars was investigated as a function of pH, contact time, and initial Cd2+ concentration. The adsorption of nonmagnetic biochars was better described by pseudo-second-order kinetic model, and the adsorption of RSB and SSB was better described by Langmuir and Freundlich models, respectively. Magnetization of the biochars did not change the applicability of their respective adsorption models, but reduced their adsorption capabilities. The maximum capacities were 42.48 and 4.64 mg/g for M-RSB and M-SSB, respectively, underperforming their nonmagnetic counterparts of 58.65 and 7.22 mg/g for RSB and SSB. Such a reduction was fundamentally caused by the decreases in the importance of cation-exchange and Cπ-coordination after magnetization, but the Fe-oxides contributed to the precipitation-dependent adsorption capacity for Cd2+ on magnetic biochars. The qualitative and quantitative characterization of adsorption mechanisms were further analyzed, in which the contribution proportions of cation-exchange after magnetization were reduced by 31.9% and 12.1% for M-RSB and M-SSB, respectively, whereas that of Cπ-coordination were reduced by 3.4% and 31.1% for M-RSB and M-SSB, respectively. These reductions suggest that for adsorbing Cd2+ the choice of conventional biochar was more relevant than whether the biochar was magnetized. However, magnetic biochars are easily separated from treated solutions, depending largely on initial pH. Their easy of separation suggests that magnetic biochars hold promise as more sustainable alternatives for the remediation of moderately Cd-contaminated environments, such as surface water and agriculture soil, and that magnetic biochars should be studied further.

Distribution and characteristics of microplastics in the basin of Chishui River in Renhuai, China.

As an emerging pollutant, microplastics widely exist in rivers all over the world. Due to the differences of economic development, economic structure and population in different regions, the abundance of microplastics in rivers is different. In those areas where agriculture is developed, the content of film microplastics is more, while in densely populated areas, the content of fibrous microplastics is more. Taking Renhuai Basin of Chishui River as the research object, the pollution characteristics and current situation of microplastics in the basin were analyzed, and the contamination risk of microplastics was evaluated. The abundance of microplastics in Renhuai basin of Chishui River ranges from 1.77 to 14.33 items/L. The main forms of microplastics were fibrous (59.4%), white (including transparent) (41.3%) and polychromatic (44.1%). The particle size of microplastics was mainly 500- 1000 µm (63.9%). According to the assessment, the risk of microplastics in the basin is 111.79, which is a secondary risk area. This study can provide a further reference for understanding the pollution characteristics of microplastics in rivers.

Occurrence and distributions of human-associated markers in an impacted urban watershed.

Numerous genetic markers for microbial source tracking (MST) have been evaluated by testing a panel of target and nontarget faecal samples. However, the performance of MST markers may vary between faecal and water samples, thereby resulting in inaccurate water quality assessment. In this study, a 30-day sampling study was conducted in an urban river impacted by human- and sewage-associated pollution to evaluate the performance of different human-associated markers in environmental water. Additionally, marker decay was assessed via a microcosms approach. Overall, Bacteroidales 16sRNA and crAssphage markers exhibited higher prevalence in the study area, and their detection frequencies exceeded 90%. In contrast, Bacteroidales protein markers exhibited poor detection frequencies compared to other markers, with the prevalence of Hum2 and Hum163 reaching only 63% and 84%, respectively. Regarding marker abundance, there was no significant difference in the detection concentrations between Bacteroidales 16sRNA and crAssphage markers (p > 0.05); however, the concentrations of Bacteroidales protein markers were nearly 1 order of magnitude lower than those of other MST markers. The microcosm experiments indicated that the decay rate of crAssphage markers was significantly lower than that of other bacterial target markers, which may improve their detectability when the pollution source is located far from the sampling site. Due to the observed differences in performance and decay patterns among Bacteroidales 16sRNA, crAssphage, and Bacteroidales protein markers, we recommend the simultaneous use of multiple markers from different target microorganisms to obtain a more comprehensive understanding of the pollution sources. This approach would also provide an accurate assessment of pollution levels and health risks.

High-efficiency removal capacities and quantitative adsorption mechanisms of Cd2+ by thermally modified biochars derived from different feedstocks.

Adsorption characteristics of Cd2+ on the three biochars modified by pyrolysis and calcination were investigated that were derived from rice straw (TRSB), chicken manure (TCMB) and sewage sludge (TSSB). The pH effect, adsorption kinetics, isotherms and thermodynamics, and desorption were determined, and qualitative analysis of adsorption mechanisms was performed by SEM, XRD, FTIR and XPS. Maximum adsorption capacities reached 177.28, 96.03 and 74.04 mg/g for TCMB, TRSB and TSSB, respectively, which were higher than that of many previously reported biochars. Even after five adsorption-desorption cycles, TCMB showed the strongest reusability without losing significantly adsorption capacity. This suggested that thermally modified biochars, particularly TCMB, could be a preferred adsorbent for Cd2+. Relative distribution of adsorption mechanisms was examined by direct and indirect calculation, in which the precipitation and cation-exchange dominated the whole chemisorption process, jointly accounting for 84% (TRSB) to 95% (TCMB) of total adsorption. While the complexation was of minor importance in total adsorption accounting for 5%-16%. The relationship of each mechanism with the properties of biochar was also discussed. These provided new insights on the adsorption effectiveness and mechanisms for Cd2+ in the aqueous solution that was critical for evaluating the application of modified biochars.

Horizontal and vertical distribution of microplastics in the Wuliangsuhai Lake sediment, northern China.

Microplastics are ubiquitous in the environment, sediments in the water body are considered as the sink of microplastics, but its accumulation and change trend have received little attention. We assessed the concentrations of microplastics in sediment samples collected in Wuliangsuhai Lake. The abundance of microplastics (0-6 cm) in surface sediment ranged from 16.5 to 72.4 particles 100 g-1 dry weight. The results show that the abundance, type and size of microplastics in surface sediment of different functional areas are different. Four sampling points were selected to investigate the vertical distribution of microplastics. The abundance of microplastics exhibited a clear decreasing trend with increased sediment depth, the abundance of microplastics in deep sediments is much less. This result shows that when estimating the storage of microplastics in sediments, if only considered the surface sediments, the assessment of microplastic storage worldwide might be underestimated.

The occurrence and abundance of microplastics in surface water and sediment of the West River downstream, in the south of China.

Microplastic pollution has aroused great concern in inland waters. Freshwater is the transport routes and potential sources for plastic fragments to the oceans. However, information especially about the occurrence of microplastics in freshwater systems is unclear in certain key areas. This work studied the distribution and characteristics for microplastics in the downstream area of West River. Both sediment and surface water detected microplastics with abundance ranging from 2560 to 10,240 items/kg and 2.99 to 9.87 items/L, respectively. Small size (<0.5 mm) and fiber were the main size and type in both surface waters and sediments. Polypropylene, polyethylene, polyethylene, polyvinyl chloride and polyethylene terephthalate were the polymer types of microplastics, as identified using a Fourier transform infrared spectrometer. In addition, findings here might be in consideration of studying about the distribution of microplastics and the degree to which they were influenced by the use of land. In descending order, the highest microplastics abundance was observed in commercial/public/recreational > residential > industrial > natural areas. Our results indicate the occurrence of high abundance microplastics in river impacted by human activities, and suggest that spatial distribution of microplastics varies between different land use areas.

Qualitative and quantitative characterization of adsorption mechanisms for Cd2+ by silicon-rich biochar.

The adsorption characteristics of rice-husk biochar (RHB) rich in silicon (Si) for Cd2+ in solution and soil were investigated. Three biochars were produced at different pyrolytic temperatures of 300 °C(RHB300), 500 °C(RHB500) and 700 °C (RHB700). The pH effect, adsorption kinetics and isotherms were examined, and chemical analyses of Cd2+-loaded biochars were conducted by SEM-EDS, FTIR, XRD and Boehm titration. Biochars produced at higher temperature have much larger pH and surface area, resulting in greater adsorption capacities and faster adsorption kinetics. Maximum adsorption capacities calculated from Langmuir isotherm were 62.75, 77.37 and 93.50 mg/g for RHB300, RHB500 and RHB700, respectively. Cd2+ adsorption was primarily attributed to cation exchange and precipitation, which jointly contributed 59.55% (RHB300) to 76.05% (RHB700) of the total adsorption, but the mechanisms of complexation and coordination were of minor importance in total adsorption. The relationship of each mechanism with biochar's properties was further discussed. Si-containing minerals within biochar made a much larger contribution to precipitation than total adsorption, as the respective contribution proportion were 33.92% and 8.33% on average. When added to highly Cd-polluted soil, the biochars could effectively reduce the availability of Cd2+ after incubation for 35 days, and ameliorate soil acidification through the speediness of Si released into soil solutions. These demonstrate that rice husk-derived biochar, produced at high temperatures, can be suitable applied to mitigate Cd-contamination of soil and water, and the presented analyses shed light on the mechanisms underlying the adsorption by this Si-rich biochar.

Adsorption Behavior and Relative Distribution of Cd2+ Adsorption Mechanisms by the Magnetic and Nonmagnetic Biochars Derived from Chicken Manure.

The present study investigated the adsorption of Cd2+ by nonmagnetic and magnetic biochars (CMB and M-CMB) derived from chicken manure, respectively. The adsorption characteristics were investigated as a function of initial pH, contact time, initial Cd2+ concentration and magnetic separation. Adsorption process of both biochars were better described by Pseudo-second-order kinetic equation and Freundlich isotherm model, which were spontaneous and endothermic in nature. It was found that maximum capacities were 60.69 and 41.07 mg/g obtained at the initial Cd2+ concentration of 180 mg/L for CMB and M-CMB, and the turbidity of adsorption-treated solution was reduced from 244.3 to 11.3 NTU after magnetic separation of 0.5 min. These indicated that M-CMB had lower adsorption capacity of Cd2+ than CMB, though it was successfully separated from the treated solutions. Furthermore, both biochars before and after adsorption were analyzed by SEM-EDS, XRD and FTIR. Adsorption mechanisms mainly included precipitation, ion-exchange, complexation and Cπ-coordination, in which precipitation and ion-exchange dominated the adsorption process by CMB, while in M-CMB, precipitation was always predominant mechanism, followed by ion-exchange. The two other mechanisms of complexation and Cπ-coordination were trivial in both biochars, jointly contributing 7.21% for CMB and 5.05% for M-CMB to total adsorption. The findings deepen our understanding of the mechanisms governing the adsorption process, which are also important for future practical applications in the removal of heavy metals from wastewater by the biochars.

Microplastics in the surface water of Wuliangsuhai Lake, northern China.

As a new type of pollutant, microplastics have attracted increased attention because of their widespread and persistent existence in the water environment. In this study, we investigated one of the eight largest lakes in China-Wuliangsuhai Lake in Inner Mongolia. The microplastic concentration in Wuliangsuhai Lake ranges from 3.12 to 11.25 n/L. The different functional areas in Wuliangsuhai can be divided into four categories, namely effluent, fishing, intake and wetland areas. The highest microplastic concentration occurs in the intake area. The collected microplastics are divided into four types, i.e., fibers, pellets, fragments and films, of which fibers are the most abundant. Among the four functional areas of Wuliangsuhai Lake, the highest fiber concentration is observed in the fishing area. The microplastics in Wuliangsuhai Lake are mainly small size, and the microplastics smaller than 2 mm account for 98.2% of the total microplastics, while the microplastic size in the intake area is relatively large. Polystyrene and polyethylene are the main polymer types. Agricultural wastewater, domestic sewage and fishery discharge have the greatest impact on the microplastic distribution. This study reveals that the inland lakes in northern China are polluted by microplastics, which may cause potential harm to the surrounding environment.

Aging mechanism of microplastics with UV irradiation and its effects on the adsorption of heavy metals.

Microplastics are formed by the degradation of plastic wastes under the action of physicochemical mechanisms in environment, and they are becoming a new type of pollutant that is attractings global attention. However, research on the aging characteristics and mechanism of microplastics is limited. The aging mechanism of Polystyrene (PS) with UV irradiation under different conditions (air, pure water and seawater) and the effect of aging on heavy metal adsorption were studied. The results show that PS have different characteristics with UV irradiation under different conditions, and the aging of PS is the most obvious in air. Based on the 2D-COS analysis, different aging mechanisms were identified under different aging conditions, aging sequence of aged PS functional groups in air and water were clearly definited. An isothermal adsorption model shows that aging can significantly increase the adsorption of heavy metals by PS. The adsorption of heavy metals is also affected by different aging methods. Over all, a 2D-COS analysis was an effective method for understanding the aging process of PS. These results further clarify the aging mechanism of PS, and provides a theoretical basis for the assessment of environmental behavior and ecological risk when microplastics and heavy metals coexist.

Performance of host-associated genetic markers for microbial source tracking in China.

Numerous genetic markers have been developed to establish microbial source tracking (MST) assays in the last decade. However, the selection of suitable markers is challenging due to a lack of understanding of fundamental factors such as sensitivity, specificity, and concentration in target/nontarget hosts, especially in East Asia. In this study, a total of 506 faecal samples comprised of human and 12 nonhuman hosts were collected from 28 cities across China and tested for marker performance characteristics. We firstly tested 40 host-associated markers based on a binary (presence/absence) criterion. Here, 15 markers (7 human-associated, 4 pig-associated, 3 ruminant-associated, and 1 poultry-associated) showed potential applicability in our study area. The selected 15 markers were then tested using qualitative and quantitative methods to characterise their performance. Overall, Bacteroidales markers presented higher sensitivity and concentrations in target samples compared to other bacterial or viral markers, but their specificity was low. Among nontarget samples, pets accounted for 43.7% and 35.7% of cross-reactivity with human-associated and poultry-associated markers, respectively. Noncommon animals, including horse and donkey, contributed 61.3% of cross-reactivity with ruminant-associated markers. When considering the quantitative distribution of markers, their concentration in nontarget samples were 1-3 orders of magnitude lower than in target samples. Moreover, a novel classification method was proposed to classify the nontarget hosts into four groups spanning "no cross-reactivity", "weak cross-reactivity", "moderate cross-reactivity", and "strong cross-reactivity" animal hosts. There were 77.9% nontarget samples identified as no cross-reactivity and weak cross-reactivity hosts, suggesting that these nontarget hosts produce little interference for corresponding markers. Our findings elucidate the performance of host-associated markers around China in a qualitative and quantitative manner, and reveal the interference degree of cross-reactivity from nontarget animals to genetic markers, which will facilitate tracking of multiple faecal pollution sources and planning timely remedial strategies in China.

High frequency discharge plasma induced plasticizer elimination in water: Removal performance and residual toxicity.

Plasticizers are widely present in water and soil environment, and they can bring enormous threats to environmental safety and human health. A discharge plasma system driven by a high-frequency electric source was used to remove the plasticizer from wastewater; and dimethyl phthalate (DMP) was chosen as the representative of plasticizer. DMP elimination performance at various operating parameters, roles of active species in DMP degradation, DMP decomposition process, and its residual toxicity after decomposition were systematically investigated. The experimental results demonstrated that almost all of the DMP and 80.4% of the total organic carbon (TOC) were removed after 30 min of treatment. The DMP decomposition process fitted well with the first-order kinetic model. Relatively higher applied voltage, lower initial concentration, and alkaline conditions favored its decomposition. •OH was the decisive species for DMP decomposition, in addition to •O2- and 1O2; while the role of hydrated electrons was negligible. The analysis of DMP decomposition process showed that the molecular structures of the DMP were destroyed, and 3-hydroxy-dimethyl phthalate, monomethyl phthalate, and phthalic acid were detected. Furthermore, the residual toxicity after DMP decomposition was analyzed via seed germination and photobacterium bioassay.

Non-thermal plasma oxidation of Cu(II)-EDTA and simultaneous Cu(II) elimination by chemical precipitation.

Cu2+ readily complexes with ethylenediaminetetraacetic acid (EDTA) to form a heavy metal complex (Cu-EDTA) that is typical in the effluents from mining and electroplating industries. It was difficult for the classical alkaline precipitation method to eliminate the heavy metal complex due to the strong bonding ability between Cu(II) and EDTA. Cu(II) release and removal performance after Cu-EDTA decomplexation in a non-thermal plasma oxidation system was carried out in this study. The removal process was characterized by chemical oxygen demand, total organic carbon, atomic force microscopy, and electroconductivity analysis. The toxicity effect of the treated Cu-EDTA solution was also tested by photobacterium bioassay. The experimental results showed that 80.2% of Cu was released and removed within 60 min of the non-thermal plasma treatment/alkaline precipitation. Relatively higher energy input, lower Cu-EDTA concentration, and acidic conditions were necessary to obtain greater Cu release and removal performance, and there existed an appropriate air flow rate for high-efficient Cu release and removal. O2-, OH, 1O2, and O3 were the main active substances leading to Cu2+ release. Its residual toxicity to P.phosphoreum sp.-T3 was significantly reduced after treatment.