Application of an Antibacterial Coating Layer via Amine-Terminated Hyperbranched Zirconium-Polysiloxane for Stainless Steel Orthodontic Brackets.

The massive growth of various microorganisms on the orthodontic bracket can form plaques and cause diseases. A novel amine-terminated hyperbranched zirconium-polysiloxane (HPZP) antimicrobial coating was developed for an orthodontic stainless steel tank (SST). After synthesizing HPZP and HPZP-Ag coatings, their structures were characterized by nuclear magnetic resonance spectroscopy, scanning electron microscopy, thickness measurement, contact angle detection, mechanical stability testing, and corrosion testing. The cell toxicity of the two coatings to human gingival fibroblasts (hGFs) and human oral keratinocytes (hOKs) was detected by cell counting kit eight assays, and SST, HPZP@SST, and HPZP-Ag@SST were cocultured with Staphylococcus aureus, Escherichia coli, and Streptococcus mutans for 24 hr to detect the antibacterial properties of the coatings, respectively. The results show that the coatings are about 10 µm, and the water contact angle of HPZP coating is significantly higher than that of HPZP-Ag coating (P < 0.01). Both coatings can be uniformly and densely distributed on SST and have good mechanical stability and corrosion resistance. The cell counting test showed that HPZP coating and HPZP-Ag coating were less toxic to cells compared with SST, and the toxicity of HPZP-Ag coating was greater than that of HPZP coating, with the cell survival rate greater than 80% after 72 hr cocultured with hGFs and hOKs. The antibacterial test showed that the number of bacteria on the surface of different materials was ranked from small to large: HPZP@SST < HPZP-Ag@SST < SST and 800 µg/mL HPZP@SST showed a better bactericidal ability than 400 µg/mL after cocultured with S. aureus, E. coli, and S. mutans, respectively (all P < 0.05). The results showed that HPZP coating had a better effect than HPZP-Ag coating, with effective antibacterial and biocompatible properties, which had the potential to be applied in orthodontic process management.

Exploring the environmental risks and seasonal variations of potentially toxic elements (PTEs) in fine road dust in resource-based cities based on Monte Carlo simulation, geo-detector and random forest model.

The environmental pollution caused by mineral exploitation and energy consumption poses a serious threat to ecological security and human health, particularly in resource-based cities. To address this issue, a comprehensive investigation was conducted on potentially toxic elements (PTEs) in road dust from different seasons to assess the environmental risks and influencing factors faced by Datong City. Multivariate statistical analysis and absolute principal component score were employed for source identification and quantitative allocation. The geo-accumulation index and improved Nemerow index were utilized to evaluate the pollution levels of PTEs. Monte Carlo simulation was employed to assess the ecological-health risks associated with PTEs content and source orientation. Furthermore, geo-detector and random forest analysis were conducted to examine the key environmental variables and driving factors contributing to the spatiotemporal variation in PTEs content. In all PTEs, Cd, Hg, and Zn exhibited higher levels of content, with an average content/background value of 3.65 to 4.91, 2.53 to 3.34, and 2.15 to 2.89 times, respectively. Seasonal disparities were evident in PTEs contents, with average levels generally showing a pattern of spring (winter) > summer (autumn). PTEs in fine road dust (FRD) were primarily influenced by traffic, natural factors, coal-related industrial activities, and metallurgical activities, contributing 14.9-33.9 %, 41.4-47.5 %, 4.4-8.3 %, and 14.2-29.4 % to the total contents, respectively. The overall pollution and ecological risk of PTEs were categorized as moderate and high, respectively, with the winter season exhibiting the most severe conditions, primarily driven by Hg emissions from coal-related industries. Non-carcinogenic risk of PTEs for adults was within the safe limit, yet children still faced a probability of 4.1 %-16.4 % of unacceptable risks, particularly in summer. Carcinogenic risks were evident across all demographics, with children at the highest risk, mainly due to Cr and smelting industrial sources. Geo-detector and random forest model indicated that spatial disparities in prioritized control elements (Cr and Hg) were primarily influenced by particulate matter (PM10) and anthropogenic activities (industrial and socio-economic factors); variations in particulate matter (PM10 and PM2.5) and meteorological factors (wind speed and precipitation) were the primary controllers of seasonal disparities of Cr and Hg.

Post-translational modifications in diabetic cardiomyopathy.

The increasing attention towards diabetic cardiomyopathy as a distinctive complication of diabetes mellitus has highlighted the need for standardized diagnostic criteria and targeted treatment approaches in clinical practice. Ongoing research is gradually unravelling the pathogenesis of diabetic cardiomyopathy, with a particular emphasis on investigating various post-translational modifications. These modifications dynamically regulate protein function in response to changes in the internal and external environment, and their disturbance of homeostasis holds significant relevance for the development of chronic ailments. This review provides a comprehensive overview of the common post-translational modifications involved in the initiation and progression of diabetic cardiomyopathy, including O-GlcNAcylation, phosphorylation, methylation, acetylation and ubiquitination. Additionally, the review discusses drug development strategies for targeting key post-translational modification targets, such as agonists, inhibitors and PROTAC (proteolysis targeting chimaera) technology that targets E3 ubiquitin ligases.

Spatial distribution characteristics and source apportionment of heavy metal(loid)s in park dust in the Mianyang urban area, China.

Park dust is a carrier of heavy metal pollutants and could potentially harm the health of urban residents. The concentrations of 10 heavy metal(loid)s (HMs) in park dust from the Mianyang urban area were analysed via X-ray fluorescence spectrometry. Based on ArcGIS spatial analysis, Spearman correlation analysis, spatial autocorrelation analysis, and the positive matrix factorization (PMF) model, the spatial distribution and sources of HMs in park dust were studied. The average contents of Zn, Co, Cu, Cr, Pb, and Ba in park dust were 185.0, 33.7, 38.7, 178.7, 51.0, and 662.1 mg/kg, respectively, which are higher than the reference values. The 10 HMs exhibited obvious spatial distribution and local spatial agglomeration patterns. High concentrations of As and Pb were primarily concentrated in the eastern part of the Mianyang urban area. High concentrations of Zn, Cr, and Cu were largely distributed in parks near the Changjiang River and Fujiang River. A high concentration of Co was concentrated in the northern region. The high-value areas of Mn, Ba, V, and Ni occurred far from the city centre and were located in the southwestern region. We found that Pb and As primarily originated from mixed traffic and natural sources; Zn, Cr, and Cu mainly originated from industrial activities; Co largely originated from building sources; and Ba, Ni, Mn, and V were mostly derived from natural sources. Mixed, industrial, building, and natural sources accounted for 24.5%, 24.8%, 24.7%, and 26.0%, respectively, of the HM sources. Co, Cu, Cr, and Zn in the Mianyang urban area were obviously influenced by human activities and should receive close attention.

Source-specific probabilistic risk evaluation of potentially toxic metal(loid)s in fine dust of college campuses based on positive matrix factorization and Monte Carlo simulation.

Contamination, hazard level and source of 10 widely concerned potentially toxic metal(loid)s (PTMs) Co, As, Pb, Cr, Cu, Zn, Ni, Mn, Ba, and V in fine dust with particle size below 63 µm (FD63) were investigated to assess the environmental quality of college campuses and influencing factors. PTMs sources were qualitatively analyzed using statistical methods and quantitatively apportioned using positive matrix factorization. Probabilistic contamination degrees of PTMs were evaluated using enrichment factor and Nemerow integrated enrichment factor. Eco-health risk levels of content-oriented and source-oriented for PTMs were evaluated using Monte Carlo simulation. Mean levels of Zn (643.8 mg kg-1), Pb (146.0 mg kg-1), Cr (145.9 mg kg-1), Cu (95.5 mg kg-1), and Ba (804.2 mg kg-1) in FD63 were significantly larger than soil background values. The possible sources of the concerned PTMs in FD63 were traffic non-exhaust emissions, natural source, mixed source (auto repair waste, paints and pigments) and traffic exhaust emissions, which accounted for 45.7%, 25.4%, 14.5% and 14.4% of total PTMs contents, respectively. Comprehensive contamination levels of PTMs were very high, mainly caused by Zn pollution and non-exhaust emissions. Combined ecological risk levels of PTMs were low and moderate, chiefly caused by Pb and traffic exhaust emissions. The non-cancer risks of the PTMs in FD63 to college students fell within safety level, while the carcinogenic PTMs in FD63 had a certain cancer risks to college students. The results of source-specific health risk assessment indicated that Cr and As were the priority PTMs, and the mixed source was the priority pollution source of PTMs in FD63 from college campuses, which should be paid attention to by the local government.

Source-specific risk judgement and environmental impact of potentially toxic elements in fine road dust from an integrated industrial city, North China.

The contamination of potentially toxic elements (PTEs) in road dust of large industrial cities is extremely serious. Determining the priority risk control factors of PTE contamination in road dust is critical to enhance the environmental quality of such cities and mitigate the risk of PTE pollution. The Monte Carlo simulation (MCS) method and geographical models were employed to assess the probabilistic pollution levels and eco-health risks of PTEs originating from different sources in fine road dust (FRD) of large industrial cities, and to identify key factors affecting the spatial variability of priority control sources and target PTEs. It was observed that in FRD of Shijiazhuang, a typical large industrial city in China, more than 97% of the samples had an INI > 1 (INImean = 1.8), indicating moderately contaminated with PTEs. The eco-risk was at least considerable (NCRI >160) with more than 98% of the samples, mainly caused by Hg (Ei (mean) = 367.3). The coal-related industrial source (NCRI(mean) = 235.1) contributed 70.9% to the overall eco-risk (NCRI(mean) = 295.5) of source-oriented risks. The non-carcinogenic risk of children and adults are of less importance, but the carcinogenic risk deserves attention. The coal-related industry is a priority control pollution source for human health protection, with As corresponding to the target PTE. The major factors affecting the spatial changes of target PTEs (Hg and As) and coal-related industrial sources were plant distribution, population density, and gross domestic product. The hot spots of coal-related industrial sources in different regions were strongly interfered by various human activities. Our results illustrate spatial changes and key-influencing factors of priority source and target PTEs in Shijiazhuang FRD, which are helpful for environmental protection and control of environmental risks by PTEs.

Ascertaining priority control pollution sources and target pollutants in toxic metal risk management of a medium-sized industrial city.

Re-suspended surface dust (RSD) often poses higher environmental risks due to its specific physical characteristics. To ascertain the priority pollution sources and pollutants for the risk control of toxic metals (TMs) in RSD of medium-sized industrial cities, this study took Baotou City, a representative medium-sized industrial city in North China, as an example to systematically study TMs pollution in RSD. The levels of Cr (242.6 mg kg-1), Pb (65.7 mg kg-1), Co (54.0 mg kg-1), Ba (1032.4 mg kg-1), Cu (31.8 mg kg-1), Zn (81.7 mg kg-1), and Mn (593.8 mg kg-1) in Baotou RSD exceeded their soil background values. Co and Cr exhibited significant enrichment in 94.0 % and 49.4 % of samples, respectively. The comprehensive pollution of TMs in Baotou RSD was very high, mainly caused by Co and Cr. The main sources of TMs in the study area were industrial emissions, construction, and traffic activities, accounting for 32.5, 25.9, and 41.6 % of the total TMs respectively. The overall ecological risk in the study area was low, but 21.5 % of samples exhibited moderate or higher risk. The carcinogenic risks of TMs in the RSD to local residents and their non-carcinogenic risks to children cannot be ignored. Industrial and construction sources were priority pollution sources for eco-health risks, with Cr and Co being the target TMs. The south, north and west of the study area were the priority control areas for TMs pollution. The probabilistic risk assessment method combining of Monte Carlo simulation and source analysis can effectively identify the priority pollution sources and pollutants. These findings provide scientific basis for TMs pollution control in Baotou and constitute a reference for environmental management and protection of residents' health in other similar medium-sized industrial cities.

Potentially toxic elements in surface fine dust of residence communities in valley industrial cities.

A comprehensive analysis of content, pollution characteristics, health hazard, distribution, and source of some broadly concerned potentially toxic elements (PTEs, Pb, V, Mn, Cr, Ba, Zn, Ni, and Cu) in surface fine dust with particle size <63 µm (SFD63) from residence communities in Xi'an, a representative valley industrial city, was conducted in this research to analyze the quality of environment and influencing factors of valley industrial cities in China. The average contents of Ba (794.1 mg kg-1), Cu (61.3 mg kg-1), Pb (99.9 mg kg-1), Zn (408.1 mg kg-1), Cr (110.0 mg kg-1), and Ni (33.4 mg kg-1) in SFD63 of Xi'an residence communities surpassed their background contents of local soil. The high enrichment-value regions of PTEs were chiefly located in the regions with high traffic flow, high population density, and areas around industries. Zn and Pb had moderate enrichment, and the overall pollution level of PTEs was unpolluted-to-moderate and moderate pollution. Three source categories (including natural geogenic source, industrial anthropogenic source, and mixed anthropogenic source of transportation, residential activities, and construction) were identified as the predominant sources for the PTEs pollution in SFD63, with the contribution levels of 29.9%, 32.4%, and 37.7%, respectively. The assessment of health risks according to Monte Carlo simulation revealed that the 95% of the non-cancer risk of PTEs to residents (the elderly, working people, and children) was less than the threshold of 1, while the probability of cancer risk exceeding the acceptable threshold of 1E-6 was 93.76% for children, 68.61% for the elderly, and 67.54% for working people. Industrial source was determined as priority pollution source and Cr was determined as priority pollutant, which should be concerned.

Applications of photothermally mediated nanohybrids for white spot lesions in orthodontics.

In orthodontic treatment, cariogenic bacteria in the oral cavity are the main cause of enamel white spot lesions (WSLs). Therefore, to effectively prevent and treat WSLs, it is crucial to inhibit the cariogenic bacterial activity while promoting the remineralization of demineralized tooth enamel. However, fluoride preparations commonly used for the prevention and treatment of WSLs can induce dental fluorosis if ingested in excess, and their remineralization effect is limited by the residual hydroxyapatite (HAp) content and salivary Ca2+ and PO43- levels. In this study, we propose a strategy (CMCS/ACP@PDA) for antibacterial and remineralization of WSLs by a nanohybrid of carboxymethyl chitosan (CMCS)-stabilized amorphous calcium phosphate (ACP) loaded polydopamine nanoparticles (PDA NPs) based on biomimetic remineralization techniques and biocompatible near-infrared (NIR) photoactivation therapy. The nanohybrid utilizes the excellent photothermal conversion ability of polydopamine for antimicrobial purposes, while CMCS with its own positive and negative charges (-NH3+ and -COO-) acts as a biomimetic mineralizing agent to stabilize ACP, supplemented with abundant Ca2+ and PO43- for remineralization of demineralized enamel. The results showed that CMCS/ACP@PDA could effectively inhibit the adhesion of cariogenic Streptococcus mutants (S. mutants) with high bactericidal rates. In addition, the remineralization of demineralized enamel by nanohybrid was more effective after 7 days of in vitro mineralization. This study provides a theoretical and experimental basis for the use of CMCS/ACP@PDA nanohybrid materials as potential materials against WSLs.

Multi-element features and trace metal sources of road sediment from a mega heavy industrial city in North China.

As the primary carrier of harmful elements, road sediment poses severe hazards to human health and ecological environment, especially in megacities. Based on the industrial cities in North China, this research focused on the multi-element features and the pollution levels, sources, and spatial distributions of trace metals in road sediment of Shijiazhuang. The mean levels of P (928.4 mg kg-1), S (1446.2 mg kg-1), Cl (783.9 mg kg-1), Br (5.3 mg kg-1), Na2O (2.0%), CaO (9.9%), Co (36.0 mg kg-1), Pb (38.0 mg kg-1), Cu (34.7 mg g-1), Zn (149.1 mg kg-1), Ba (518.1 mg kg-1), and Sr (224.9 mg kg-1) in road sediment were greater than their soil background values. Trace metals in most samples was moderately (75%) and heavily contaminated (15.6%). The industrial areas, congested roads, and residential areas in the northeast, middle and south of Shijiazhuang are the hotspots of trace metals pollution. A comprehensive analysis of trace metals sources indicated that Ni, V, Ga, Rb, Y, Sc, La, Ce, Zr, and Hf were mainly from natural source, which contributed to 34.2% of the total trace metals concentrations. Cu, Pb, Zn, Cr, Ba, Sr, and Mn primarily originated from mixed source, which accounted for 46.5%. Co principally came from building source, which accounted for 19.3%. This study shows that industrial discharges, construction dust and traffic emissions are the primary anthropogenic sources of trace metals in road sediment in the study area.

Contamination and Probabilistic Ecological-Health Risk of Heavy Metal(loid)s in Urban Topsoil of Mianyang, SW China.

Heavy metal(loid) (HM) pollution in urban topsoil seriously endangers the health of urban residents and urban sustainable development. Compared with large cities, the research on the HM pollution of topsoil in emerging medium-sized industrial cities is quite limited. This study focuses on topsoil HM contamination in Mianyang, which is a representative moderate emerging industrial city in Southwest China. The results indicate that Ba, Cr, Cu, and Zn in the samples were much higher than their background values. The hot spots of Ba, As, Cu, Pb, Co, Cr, and Zn showed an obvious enrichment trend. The potential ecological risk of HMs showed a low ecological risk, which was mainly caused by As. The investigated HMs presented no significant non-carcinogenic hazard to local adult residents, but there were three sampling sites which presented a non-carcinogenic hazard to children; the carcinogenic risks of As, Cr, Co, and Ni were acceptable. In this study, a mixed source of industry and traffic was identified to be the priority anthropogenic source, and Cr and As were identified as the priority elements for further risk control. The findings of our study could be beneficial to decision-makers with regard to taking appropriate measures to control and reduce HM pollution in the Mianyang urban area.

Reducing traffic violations in the online food delivery industry-A case study in Xi'an City, China.

Online food delivery (OFD) is one of the top industries in the Online-to-offline (O2O) commerce sector. Deliverymen need to complete a large number of delivery orders in limited default time every day, which cause high working stress to them. Therefore, a high level of traffic violations and crashes by deliverymen and corresponding negative impact on public safety are observed. To reduce traffic violations by deliverymen and resulting crashes, a hierarchical online food delivery framework is proposed, which is based on data from questionnaire surveys conducted in Xi'an City, China. The study includes the analysis of the root cause correlated with traffic violations during online food delivery as part of an empirical study on the priority delivery fee by applying a conditional price sensitivity measurement (PSM) model. The feasibility and rationality of the framework are further investigated by using cross analysis of urban dwellers' occupation, income, and commuting cost. The results identify that, through rationally shunting the demand of online food delivery, prolonging the default delivery duration, and providing diversified delivery services, the proposed hierarchical online food delivery mechanism is able to relieve the stress of deliverymen during peak hours of food requests. This reduces the willingness of deliverymen to engage in traffic violations, and other risky behaviors during food delivery trips. All of which facilitate high-quality and timely online food delivery service while enabling improved safety of deliverymen and others as part of enhanced public safety and health.

Spatial distribution and source apportionment of heavy metal(loid)s in urban topsoil in Mianyang, Southwest China.

Spatial distributions and sources of some commonly concerned heavy metal(loid)s (HMs, As, Ba, Cr, Co, Cu, Ni, Pb, Mn, Zn, and V) in topsoil of Mianyang city, a typical medium-sized emerging industrial city in Southwest China, were determined to explore the influences of anthropogenic activities on the urban environment. The contents of the 10 HMs in 101 topsoil samples were analyzed using an X-ray fluorescence spectrometer, and their sources were analyzed by positive matrix factorization and statistical analysis. The spatial distributions of the HMs and the source contributions were mapped using GIS technology. The results showed that the mean contents of Ba, Cr, Cu, and Zn in the topsoil were significantly higher than their background values. Industrial activities resulted in high contents of Ba, Zn, Cu, and Cr. As, Co, Ni, and V that primarily came from natural sources; Pb, Cr, Cu, and Zn were chiefly derived from a mixed source of industry and traffic; and Ba and Mn primarily originated from industrial sources. Natural sources, mixed sources, and industrial sources contributed 32.6%, 34.4%, and 33.0% of the total HM contents, respectively. Industrial sources and mixed sources of industry and traffic were the main anthropogenic sources of HMs in the urban topsoil and should be the focus of pollution control.

Spatial distribution, risk estimation and source apportionment of potentially toxic metal(loid)s in resuspended megacity street dust.

The levels of potentially toxic metal(loid)s (PTMs) As, Cu, Co, Cr, Hg, Mn, Ni, Pb, and Zn in resuspended street dust (<100 µm particles) from a megacity in north China were determined. The sources of PTMs in resuspended street dust were analyzed using multivariate statistical analysis and positive matrix factorization methods that combined the spatial distributions of PTMs. Average levels of Zn, As, Pb, Cu, Co, and Hg exceeded those found in local soil samples, while those of Cr, Mn, and Ni were less than their background levels found in local soil. The overall contamination of PTMs in resuspended street dust was characterized as moderately contaminated and as uncontaminated to moderately contaminated. The ecological risk associated with Hg was very high, while the ecological risks associated with Cu, Co, Cr, Mn, Ni, Pb, and Zn were low. The overall ecological risk of PTMs was defined as high, driven by Hg. The non-carcinogenic risks of PTMs to inhabitants fell within safety limits, and the carcinogenic risks of As, Co, Cr, and Ni were below receivable values. A comprehensive analysis of PTMs sources revealed that Co, Zn, Cu, and Pb were principally associated with traffic emissions, which accounted for about 38.3% of these PTMs' contents. Mn, Ni, and Cr were mainly generated by natural source, which contributed to about 41.5% of these PTMs' concentrations. Hg and As were primarily derived from coal-related industrial source, which accounted for 77.9% of Hg and 62.9% of As in resuspended street dust. This study demonstrates that coal-related industrial discharges and traffic emissions are the main anthropogenic sources of PTMs contamination in resuspended street dust in the study area.

Spatial distribution, pollution level, and health risk of Pb in the finer dust of residential areas: a case study of Xi'an, northwest China.

The spatial distribution, pollution level, and exposure risk of Pb in the finer dust (particle size < 63 µm) of residential areas in Xi'an, northwest China were investigated in this study. Geographical information systems and geodetector methods were used to analyze the spatial variability of Pb content in the finer dust of Xi'an and its forming mechanism. The enrichment factor was used to assess the extent of Pb pollution, and the hazard index was used to evaluate the health risks to children and adults exposed to Pb. The results showed that the average content of Pb in the finer dust of residential areas in Xi'an was 99.9 mg kg-1. In the Xi'an urban area, a higher Pb content was mainly found in the finer dust near the Second Ring Road of Xi'an City, and the Pb content in the old town of Xi'an City was relatively lower than that near the Second Ring Road. The results of geodetector analysis indicate that the spatial variability of Pb in the finer dust of the Xi'an urban area was primarily controlled by the interaction among vehicle emissions, daily behavior of residents, and industrial emissions. Pb in the finer dust from residential areas in all districts showed moderate enrichment. The non-cancer risks of Pb in the finer dust were within the safe range for both children and adults. However, the prolonged exposure risk of Pb in the finer dust of residential areas should be considered for children.

Risk and sources of heavy metals and metalloids in dust from university campuses: A case study of Xi'an, China.

College students study and live at university for several years; however, the pollution levels, ecological health risks, and sources of heavy metals and metalloids (HMMs) in the dust found at university campuses are still unknown. In this study, dust samples from university campuses in Xi'an were collected and the Zn, Mn, As, Pb, V, Cr, Co, Cu, Ba, and Ni contents were measured using X-ray fluorescence spectrometry. The pollution levels and ecological health risks of these HMMs were evaluated using the geo-accumulation, pollution load, and potential ecological risk indices and a health risk assessment model while their sources were apportioned using positive matrix factorization. The mean HMM concentrations in the dust were higher than the corresponding background values in the topsoil of Shaanxi Province. The Mn, V, Co, As, and Ni concentrations in the dust samples analyzed were within the levels categorized as no pollution by the geo-accumulation index standard, whereas other HMMs caused pollution to different degrees. Assessment of the pollution load index indicated that the dust samples analyzed were moderate contamination with HMMs. Pb and Cu in the dust presented considerable and moderate ecological risks, respectively; the other HMMs presented low ecological risks. The combined ecological risk of the HMMs measured in the dust samples was considerable. The non-carcinogenic and carcinogenic risks to male and female college students were within the safe levels. This study found three main sources of the HMMs measured in the dust: traffic, natural, and mixed sources (the latter including automobile repair industry waste and paints and pigments), which accounted for 47.5%, 29.3%, and 23.2% of the total HMM concentration, respectively.

Analyzing environmental risk, source and spatial distribution of potentially toxic elements in dust of residential area in Xi'an urban area, China.

A comprehensive study on concentration, spatial distribution, pollution, ecological-health risk and source of potentially toxic elements (PTEs) in dust of residential area in Xi'an, China were conducted to explore the environmental quality of residential area in urban district. The results show that the concentrations of V, Ni, and Mn in the dust were less than, while the contents of Cr, Zn, Pb, Cu, and Ba in the dust were obviously larger than, the soil background values of Shaanxi. The high-value area of PTEs primarily concentrated in densely populated areas, heavily trafficked areas and the surroundings of plants. Cr, Pb and Zn posed moderate enrichment and Pb possessed moderate ecological risk in the dust. The comprehensive pollution levels of PTEs in the dust were uncontaminated to moderately contaminated and their comprehensive ecological risk were moderate. The non-carcinogenic risks of the PTEs for adults and children were in the safe level and the carcinogenic risks of Ni and Cr were under the current acceptable value. Four major sources were discriminated on basis of the multivariate statistical analysis results and the content characteristics, enrichment degrees, and the spatial distribution features of the PTEs, viz. Mn, V, and Ni primarily came from natural source; Pb, Zn, and Cu mainly originated from traffic source; and Ba and Cr were respectively from construction source and coal-fired power plant source, which respectively contributed 22.8%, 28.3%, 47.3%, and 1.6% to the total content of PTEs determined in the dust.

[Pollution and Source Analysis of Heavy Metal in Surface Dust from Xi'an University Campuses].

Surface dust samples were collected from university campuses in Xi'an, and X-ray fluorescent spectrometry was used to determine the contents of nine heavy metals (Mn, As, Pb, Cr, Co, Ni, Cu, V, and Zn). Enrichment factors were subsequently used to determine the enrichment degree of each element and the preliminary determination of the pollution sources. The R programming language and SPSS were used for cluster analysis and principal components analysis to identify the pollution sources. The results showed that the average concentrations of all nine heavy metal elements were higher than their surface soil background values in Shaanxi Province; however, Mn, Co, As, V, and Ni exhibited relatively little enrichment and were less affected by human interference. Cr and Cu were moderately enriched, whereas Zn and Pb were significantly enriched, and human activities played a major role in the enrichment of these four elements. The main sources of Mn, Co, As, V, and Ni in surface dust samples from the university campuses were natural sources, whereas the accumulation of Zn, Cr, and Pb were mainly due to traffic sources, and Cu originated both from the auto repair industry and from paint coatings.

[Source Identification and Pollution Characteristics of Heavy Metals in Suspended Particles of Urban Road Dust from Xingtai City].

Fifty dust samples were collected from Xingtai City to study the source characteristics of heavy metals in suspended particles of urban road dust from industrial enterprise transformation cities. The contents of Cr, Mn, Co, Ni, Cu, Zn, As, and Pb in particles of urban road dust smaller than 100 µm were determined by X-ray fluorescence spectrometry, and their pollution levels were assessed by enrichment factor. The possible sources of heavy metals measured in the dust were identified by multivariate statistical analysis methods including correlation analysis, principal component analysis, and cluster analysis. The results indicated that in comparison to the element background values of local soil, the particles of urban road dust smaller than 100 µm from Xingtai City had higher Cr, Mn, Co, Cu, Zn, and Pb concentrations. The accumulation level of Co was the highest, followed by Zn, and Pb and Cu, whereas the other trace metals were deficient or showed minimal enrichment in the suspended road dust. The multivariate statistical analysis results showed that Cr, Mn, and Ni had significant positive correlation. These metals belong to both a principal component and a cluster, whereas Cu, Zn, and Pb belong to just a principal component. Considering the content characteristics and the results of multivariate statistical analysis of various heavy metal elements in the suspended samples, these results illustrated that the Cr, Mn, and Ni in the suspended particles of urban dust from Xingtai City roads mainly come from natural and industrial sources, whereas the Zn, Pb, and Cu originate from transportation and coal sources; As comes from natural sources, and Co is mainly affected by industrial activities.

Concentrations, Speciation, and Bioavailability of Heavy Metals in Street Dust as well as Relationships with Physiochemcal Properties: A Case Study of Jinan City in East China.

A total of 77 street dust samples were collected from Jinan City in East China and were analyzed for the concentrations, speciation, bioavailability, and influencing factors of ten heavy metals. The results showed that the average concentrations of Ba, Co, Cr, Cu, Cd, Mn, Ni, Pb, Zn, and V in the street dust were 642.77, 8.24, 114.09, 87.71, 1.08, 517.04, 30.29, 80.32, 497.84, and 51.76 mg/kg, and the concentrations of Ba, Cr, Cu, Cd, Ni, Pb, and Zn exceeded the local soil element background values. In the street dust, Ba, Co, Cr, Mn, Ni, and V were mainly in the residual; Cu and Pb were controlled by the oxidizable; Cd mainly existed in the acid extractable; and Zn was dominated by the reducible. According to the ratios of the acid extractable to the sum of four forms, Cd (39.85%) presented a high environmental risk; Mn and Zn (24.29% and 27.78%) exhibited a medium risk; and V, Cu, Pb, Ba, Co, Ni, and Cr had no environmental risk. The order of mobility or potential risk of heavy metals was Cd ( 85.8%) > Zn (77.1%) > Cu (64.3%) > Pb (62.0%) > Mn (51.7%) > Ba ( 38.9%) > Co (31.2%) > Ni (30.1%) > V (25.8%) > Cr (23.1%), suggesting that Cd, Zn, Cu, Pb, and Mn presented relatively high movability and risk. The bioavailability order of heavy metals was Cd (82.7%) > Zn (63.6%) > Mn (40.4%) > Ni (20.4%) > Pb (11.7%) > Cu (11.1%) > V (7.8%) > Cr (3.7%) in the gastric phase and Cu (24.6%) > Cd (19.9%) > Mn (16.2%) > Ni (6.6%) > Pb (5.7%) > Zn (4.4%) > Cr (3.0%) > V (2.3%) in intestinal phase, implying that Cd, Zn, Mn, and Cu were highly bioavailable in the gastrointestinal environment, which coincided with the risk of speciation. The speciation of heavy metals in street dust had certain correlations with their bioavailability. The physiochemical properties of street dust had significant effects on the concentrations, speciation, and bioavailability of heavy metals in street dust. The simple, fast, and nondestructive magnetic measurements could be used as indicators of the concentrations, speciation, and bioavailability of heavy metals in street dust.