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In order to better understand both the conceptual and operational aspects of bioaccessibility and phytobioavailability of PTMs (Co, Cr, Cu, Li, Mn, Ni, Pb, Zn) in different urban soils, a total of 30 soil samples from agricultural region, entertainment district, education area, traffic area, residential area and industrial area (IA) in Baoji urban city (NW China) were collected and the bioaccessibility and phytobioavailability were measured by multi-in vitro models of PBET, SBET, citric acid leaching and Tessier sequential extraction procedure, respectively. The suitable in vitro measurement of bioaccessibility and phytobioavailability for each PTM was selected and would be reliably applied for health risk assessment. The results indicated that the bioaccessibility and phytobioavailability for each PTM evaluated by in vitro models depended on PTM total concentration and anthropologic activity influence. The health risks associated with bioaccessibility of PTMs exposure showed that the carcinogenic and non-carcinogenic risks in all areas for children and adults were below the threshold or acceptable risk levels except lead exposure on children in IA, indicating there were more health risks to the children in than that in other functional areas. It was worth that the highest observation of Pb in IA would strongly correlate with lead–acid battery industries, which the emissions would influence on the occurrences of Pb distributing in the other functional areas, which were supported from the analysis results of XPS. Therefore, the continuous monitoring and attention to the health risk of inhabitants in different functional areas should be paid. [ABSTRACT FROM AUTHOR]

A total of 155 urban soil and 157 dust samples were collected from Xining city (NW, China) with the objective to systematically investigate the spatial occurrences, sources, and health risk status of potential toxic metals (PTMs) bound in urban soil and street dust. Results established by Geographic Information System tools with inverse distance weighted interpolation technique indicated that the spatial status of 24 multi-PTMs varied with their concentration levels in urban soils and street dusts in monitored local areas. However, they had the similar sources in soil and dust. It was found that Bi, Ga, Nb, Ni, Rb, Sr, Th, U, Y, Zr, As, Mn, Nb, Ti, and V would be possibly predominated by nature material, whereas contamination of Ba, Cr, Cu, Pb, and Zn was clearly related to traffic-related sources. Peculiar associations among Sb, Sn, Ce, and Co were possibly enriched in soil and dust very close to the industrial activities. It was noted that PTMs in urban soil was an important contributor to them in dust. Compared with the potential ecological risk index of all PTMs, Sb posed very high risk. The calculated hazard index and cancer risk of all PTMs suggested the acceptable range both to noncarcinogenic and carcinogenic risk to children and adults except for the case of Cr. However, the noncarcinogenic risk for children was usually higher compared with adults. Although the noncarcinogenic and carcinogenic risk were not significant, the risk of Cr above the threshold for children and adults were observed in most local sites, which should be given more attention. [ABSTRACT FROM AUTHOR]

Street dusts (SDs) were a significant tracer to understand the pollution status of potentially toxic metal/metalloids (PTMs) in local environment. In this study, a total of 157 SDs were collected in the valley-city of Xining, NW China, with the objective to systematically investigate the spatial occurrences, sources and health risk status of 24 PTMs bound in SDs. The basic datasets of pH and size-fractions showed that the SDs with PTMs were more alkaline and dominated with the coarse particle sizes between PM10–50, respectively. Results of concentration levels and spatial status of 24 PTMs processed with multi-statistical tools well established the sources identification in monitored local areas. It was suggested that the principal elements, Al, Fe, Si, K, Ca, Na, Mg, coupled with the trace elements Bi, Ga, Nb, Ni, Rb, Sr, Th, U, Y, Zr, As, Mn, Ti, V, Ce and La would be possiblely predominated by geogenic source or nature material, whereas contamination of Ba, Cu, Pb and Zn was clearly related to traffic-related sources. Peculiar associations among Cr and Co were possiblely enriched in SDs very close to the alloy industries. However, Sb and Sn differed from other observed PTMs, which appeared to derive predominantly from the coal combustion other than sources of electronic and mechanical industries. Compared to the integrated potential ecological risk index (PERI) of all PTMs with considerable contamination level and ecological risk, the single PTM of Sb posed very high risk. Calculated Hazard Index (HI) suggested ingestion as the most important exposure pathway for the majority of PTMs in children and adults, and no significant health risks of non-carcinogenic to children and adults were found except Cr (2.78) exposured to children. However, the evaluated cancerous risk was in the acceptable range both to children and adults except for the case of Cr exposure to adults (1.55E-06) compared to other PTMs. Although the carcinogenic risk was found no significant level, the maps of spatial carcinogenic risks above the threshold for children and adults were observed in some local monitoring areas, which should be attention and not to be always ignored. [ABSTRACT FROM AUTHOR]

The fate and risk in the environment of potentially toxic metals (PTMs) pollutants depends on the size-fractions of contaminated soil. In this study, the variable micro-nano size-fractions of 50–250 μm, 5–50 μm, 1–5 μm, <1 μm in long-term Pb-contaminated alkaline soil (NW China) were obtained by Sequential Wet Sieving Separation Procedure (SWSSP). The chemical speciation, mobility and risk of PTMs in micro-nano particle fractions as well as their uptaken and translocation in Maize (Zea mays L.) plant were systematically determined. The results demonstrated that higher accumulation of both investigated PTMs was observed in the fine fractions of <1 μm. The metallic Pb predominantly occurred in all size-fractions (65%–86%) identified by XPS, and the reducible forms of lead oxide (Ⅱ,Ⅳ) would also likely preferred to enrich in the fine fraction of <1 μm. The mobility and bioaccessibility of PTMs in fine fraction of <1 μm were higher than other fractions, which were identified by the multi-indices, enrichment factor (EF), accumulation factor (AF), mobility factor (MF), potential ecological risk index of single metal (E r i) and the comprehensive potential ecological risk index (RI). The scenario for phyto-uptake of Pb and Cu in <1 μm soil nanoparticles under pot tests indicated that the Pb and Cu enriched in <1 μm with high ecological risk were inclined to translocate into the Maize roots and shoots with nano size fractions. The results implied that further environmental management should be needed in order to prevent the risk of PTMs from Pb-bearing micro-nano size fractions in the industrial contaminated alkaline soil. [Display omitted] • Size-fractions of Pb-contaminated alkaline soil affected the PTMs fate and risk. • Pb in micro-nano size-fractions from alkaline soils had higher mobility and risk. • Pb and Pb(Ⅱ,Ⅳ) oxide in fine size-fractions emitted from industry were the possible source of BLLs. • Pb and Cu in fine size fraction uptaken by Maize and translocate in nano-size particles mostly. [ABSTRACT FROM AUTHOR]

Potentially toxic metals (PTMs), associated with different size particles in soil, may play an important role in adverse health effect and risk for human. The objective is to evaluate the lung and gastrointestinal bioaccessibility and risk of PTMs in Pb-contaminated alkaline urban soil depending on the particle size fractions. The size fractions of 50–250 μm, 5–50 μm, 1–5 μm, <1 μm in Pb-contaminated alkaline urban soil from Baoji Heavy Industrial Base City, NW China, were screened by Sequential Wet Sieving Separation Procedure (SWSSP) based on Stokes' Law. The concentrations of 9 potentially toxic metals (As, Ba, Co, Cr, Cu, Mn, Ni, Pb and Zn) in each particle size fractions were characterized by ICP-OES and ICP-MS, and the in vitro bioaccessibility dependent of size fractions were evaluated by the simulation fluids of Artificial Lysosomal Fluid (ALF) and Gamble for lung, PBET, SBET, IVG, SBRC, UBM for gastric and intestinal, respectively. Health risks were assessed considering simulated external exposure using intestinal and lung bioaccessibility. The lung and gastrointestinal bioaccessibility and exposure risks of PTMs in fine particle size (i.e. <1 μm) was higher than larger particle size fractions (i.e. 50–250 μm, 5–50 μm, 1–5 μm), however, some different variations of bioaccessibility observed the simulation fluids and time dependent. In case of single PTMs, the lung bioaccessibilities of PTMs in ALF were higher than those in Gamble fluids, most prominent in Co, Cu, Mn and Zn, while the gastrointestinal [G + I] bioaccessibility of PTMs was less than those in gastric [G], like Cu, Mn, Pb and Zn mostly. The non-carcinogenic risks of these PTMs to children via inhalation were acceptable and higher than those of adults, but reverse for carcinogenic risk. Comparatively, the non-carcinogenic and carcinogenic risks of PTMs via ingestion pathway were both higher than those for adults. Although the risks from ingestion were in acceptable range, the total carcinogenic risks for children were more than 10−4, which would bring carcinogenic risks and should be paid attention to. It was noted that the toxic metal, Co in all size fractions was the most important contributor for noncarcinogenic risks and Cr mostly for carcinogenic risks via inhalation pathway for adults and children in local areas. However, Pb was the most important contributor for noncarcinogenic risk both for adults and children via ingestion pathway relative to Co and Cr for carcinogenic risks through hand-to-mouth ingestion. Those observations demonstrated the important role that the smaller particle fractionations in Pb-contaminated alkaline soil played in both bioaccessibility and the refinement of human health-risk assessments for the inhalation and ingestion pathway. Image 1 • A novel Sequential Wet Sieving Separation Procedure were developed for separating < 1 μm portions from bulk soils. • In vitro lung and gastrointestinal bioaccessibility and exposure risks of metal (loids) dependent of soil size fractions. • Simulated internal exposure methodology of lung and gastrointestinal in vitro has the selectivity for metal (loids). • TOC and chemical forms (PbSO 4 , PbO and PbO 2) would increase the bioaccessibility of Pb in soil size fractions. • Pb, Co, Cr were the predominant contributors for noncarcinogenic and carcinogenic risks via inhalation and ingestion. [ABSTRACT FROM AUTHOR]

Atmospheric fallouts (AFs) were collected in the south of Xi'an, NW China, during the dust episodes of 2001–2012. The chemical characteristics of total 68 AF samples including their chemical compositions, size distribution and magnetic susceptibility were studied. The contamination degree and the source of heavy metals in AF were also explored with enrichment factor method and multivariate statistical analysis. The results showed that the particle mass size distribution of AFs dominated by coarse particles (PM10–50) in dust days. The concentrations of 26 elements associated with AFs determined by wavelength dispersive X-ray fluorescence spectrometry (WDXRF) in studied sites varied from 92.90 to 188.10 mg kg−1 for Cr, 31.40 and 63.00 mg kg−1 for Cu, 16.60 to 167.30 for Pb and 106.60 to 196.80 for Zn. Their average concentrations found in this study were 139.22 ± 29.41 mg kg−1, 46.93 ± 10.56 mg kg−1, 78.42 ± 46.52 mg kg−1 and 150.61 ± 32.84 mg kg−1, respectively, which exceeded their corresponding recommended background values more than two times. While, other elements, such as Br varied from 1.10 to 5.90 with 3.34 ± 1.60 mg kg−1 mean, Cs from 2.90 to 10.90 with mean of 7.23 ± 2.47 mg kg−1, Ga between 6.90 and 20.80 with 15.23 ± 3.59 mg kg−1, Rb in the range of 62.10–124.20 with the average of 80.69 ± 16.89 mg kg−1, Y from 9.90 to 35.00 with 20.43 ± 6.27 mg kg−1 average, La from 29.60 to 54.20 with mean of 37.28 ± 8.28 mg kg−1 and V with average of 81.97 ± 8.93 mg kg−1 in the 57.7–92.10 mg kg−1. Multivariate statistical analysis (principal component analysis and clustering analysis) was suggested that the principal element elements, Al, Fe, Si, K, Ca, Na, Mg, coupled with the trace elements Co, V, Ce, Mn, Ni, Ga, Y, Rb, La, Br, Cs were predominated by crustal material sources, whereas, Cr, Cu, Ba, Sr, As, Pb and Zn were highly influenced by anthropogenic activities. Simultaneously, the water-soluble ions (WS-ions) of NH4 +, SO4 2−, SO3 2−, NO3 −, SiO4 4−, HSO4 − contained in APs identified by FT-IR spectroscopy were possible originated from coal combustion. The results were also confirmed and consistent with the observations of magnetic susceptibility (MS), enrichment factor (EFs) and contamination evaluation analysis. With such rates of atmospheric fallouts that contain elevated levels of toxic elements during the dust storm condition, actions should be taken to continually examine and understand of the potential impacts of AFs on surface ecosystem, water resource, and human health in the dust storm condition. [ABSTRACT FROM AUTHOR]