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Soluble iron (FeS) in aerosols contributes to free oxygen radical generation with implications for human health, and potentially catalyzes sulfur dioxide oxidation. It is also an important external source of micronutrients for ocean ecosystems. However, factors controlling FeS concentration and its contribution to total iron (FeT) in aerosols remain poorly understand. Here, FeS and FeT in PM2.5 was studied at four urban sites in eastern China from 21 to 31 December, 2017. Average FeT (869–1490 ng m−3) and FeS (24–68 ng m−3) concentrations were higher in northern than southern China cities, but Fe solubility (%FeS, 2.7–5.0%) showed no spatial pattern. Correlation analyses suggested %FeS was strongly correlated with FeS and PM2.5 instead of FeT concentrations. Individual particle observations confirmed that more than 65% of nano-sized Fe-containing particles were internally mixed with sulfates and nitrates. Furthermore, there was a high correlation between sulfates or nitrates/FeT molar ratio and %FeS. We also found that the sulfates/nitrates had weaker effects on %FeS at RH 50%, suggesting RH as indirect factor can influence %FeS in PM2.5. These results suggest an important role of chemical processing in enhancing %FeS in the polluted atmosphere.

The minimization of Cd pollution in wheat is urgently needed in many parts of the world. Thus, the aims of the present study were to evaluate the feasibility of popular technologies (i.e., soil amendment and low-Cd wheat cultivar) at sites with different Cd risk levels (high and low) and to propose a risk-based strategy for safe grain production. At a high-Cd site, wheat variety JM22 yielded significantly lower grain Cd than SX828, regardless of soil amendment (biochar, sepiolite, and microbial agent YZ1). Neither biochar nor sepiolite amendment reduced grain Cd, DTPA-Cd, or bioconcentration factors, possibly due to low dosage. Metagenomic sequencing and quantitative PCR showed that YZ1 colonization had little effect on rhizospheric fungal community structure and could not be sustained through winter. At a low-Cd site, significantly lower grain Cd was observed in JM22, LX99, and JM262, which could be used as low-Cd cultivars in the study area. Interestingly, the grain Cd of JM22 was linearly correlated with soil Cd (R2 = 0.84), which allowed the inference of a soil Cd threshold of 1.55 mg·kg−1, below which JM22 alone was capable of producing safe grain. Cost-benefit analysis also indicated that the use of low-Cd cultivars is promising for pollution control. This study provides viable technical solutions for minimizing the grain Cd of wheat grown in northern China.

Heavy metal risks to human health in farmland of wastewater-irrigated areas have long been recognized. It remains to be shown whether farmland heavy metals from wastewater irrigation can migrate to deeper soil at a regional scale. In this study, nine soil cores deep to 30 m from three transects (A, B and C) of a linear wastewater reservoir and the adjacent farmland topsoils and wheat grains were sampled. Heavy metals including As, Cd, Cr, Cu, Pb and Zn in the soils and wheat grains were determined, and the grains’ health risks were assessed using the Target Hazard Quotient (THQ). Considerably high contents of heavy metals in both total and soluble forms were detected in deep soils, especially for the transect B where total As of 73.0 mg kg−1 at 29 m, Cd of 3.80 mg kg−1 at 13 m and Pb of 214 mg kg−1 at 30 m were detected. The silty clayey and silty layers of the transect B had higher contents of As, Cr, Cu, Pb and Zn compared with the sandy layers. Across the studied area, 19.5%–34.1% of the topsoil samples were contaminated by As, Cd, Cu, Pb and Zn, and 34.1% and 19.5% of the wheat grains were contaminated by Cd and Pb, respectively. Wheat grains from all the sampling sites had a combined target hazard quotient (TTHQ) value of >1, with As and Cd being the most important contributors. Our study revealed a wider and deeper risk of typical heavy metals originated from long-term wastewater irrigation in the sampling area, which may pose substantial health risks to the local residents via wheat grains and groundwater.

The atmospheric pollution created by coal-dominated industrial cities in China cannot be neglected. This study focuses on the atmospheric PM10 in the typical industrial city of Pingdingshan City in North China. A total of 44 PM10 samples were collected from three different sites (power plant, mining area, and roadside) in Pingdingshan City during the winter of 2013, and were analyzed gravimetrically and chemically. The Pingdingshan PM10 samples were composed of mineral matter (average of 118.0±58.6μg/m(3), 20.6% of the total PM10 concentration), secondary crystalline particles (338.7±122.0μg/m(3), 59.2%), organic matter (77.3±48.5μg/m(3), 13.5%), and elemental carbon (38.0±28.3μg/m(3), 6.6%). Different sources had different proportions of these components in PM10. The power plant pollutant source was characterized by secondary crystalline particles (377.1μg/m(3)), elemental carbon (51.5μg/m(3)), and organic matter (90.6μg/m(3)) due to coal combustion. The mining area pollutant source was characterized by mineral matter (124.0μg/m(3)) due to weathering of waste dumps. The roadside pollutant source was characterized by mineral matter (130.0μg/m(3)) and organic matter (81.0μg/m(3)) due to road dust and vehicle exhaust, respectively. A positive matrix factorization (PMF) analysis was performed for PM10 source apportionment to identify major anthropogenic sources of PM10 in Pingdingshan. Six factors-crustal matter, coal combustion, vehicle exhaust and abrasion, local burning, weathering of waste dumps, and industrial metal smelting-were identified and their contributions to Pingdingshan PM10 were 19.0%, 31.6%, 7.4%, 6.3%, 9.8%, and 25.9%, respectively. Compared to other major cities in China, the source of PM10 in Pingdingshan was characterized by coal combustion, weathering of waste dumps, and industrial metal smelting.

PM10 samples were collected on haze days (visibility

A total of 19 24-h PM 10 samples, the 11 for a typical coal industrial city and 8 for a non-coal industrial city, were collected by a TSP-PM 10 sampler during a serious and continuous haze event in Henan Province, North China. An X-ray diffractometer (XRD) was used to determine the mineralogy and a scanning electron microscope equipped with an energy-dispersive X-ray spectrometer (SEM-EDS) was used to determine the morphology and chemical composition of the PM 10 samples. The crystalline phases that were identified by XRD mainly include sulfate (dominated by koktaite, boussingaultite, gypsum, etc.) and silicate (quartz and kaolinite) as well as small amount of chloride (sal-ammoniac). Silicate particles mainly originate from crust as well as waste dumps for coal industrial cities, and usually have an irregular shape, while sulfate particles occur as individual sheets or needles, and have an anthropogenic origin, which are the products of chemical reaction of preexisting carbonate with SO 2 emitted by coal combustion. Nitrogen, S and Cl occurring in particulate matter are considered to have an anthropogenic origin due to their high enrichment factors, and their abundance in particulate matter is associated with coal industrial activities. Nitrogen mainly occurs as NH 4 + in sulfate, as well as in small amount of organic matter. Sulfur mainly occurs as SO 4 2 − in sulfate. Chlorine mainly occurs in chloride.

Oxidative damage to plasmid DNA induced by airborne PM10 (particulate matter with an aerodynamic diameter of 10 μm or less) is caused by the bioavailable (i.e., soluble) heavy metals on the particle surface. However, quantitative analyses of the links between PM10 and oxidative damage are limited. In this study, plasmid DNA assay and ICP-MS were applied to study oxidative capacity and trace element compositions, respectively, of summer and winter PM10 samples collected at several sites (Sun Yat Sen Municipal Park (SYSP) and Av. de Horta e Costa (AHC) on the Macao peninsula and Macao University on Taipa Island (TI)) in Macao. At AHC and TI, the oxidative capacity of PM10 collected in winter was higher than that collected in summer, for both the whole sample and the water-soluble fraction. In contrast, no seasonal variation was noted at SYSP. PM10 exhibited the highest oxidative capacity at SYSP and lowest oxidative capacity at TI in both seasons, demonstrating that the PM10 collected on the Macao peninsula had a higher toxicity than that from Taipa Island. ICP-MS analyses revealed that the concentrations of total analyzed trace elements and their water-soluble components in PM10 from TI and AHC were higher in winter than in summer, whereas SYSP displayed the opposite trend. The extents of oxidative damage induced by the water-soluble fractions and intact whole particles were generally similar, implying that the oxidative damage caused by particles in Macao resulted mainly from the water-soluble fraction. The oxidative capacities of PM10 were positively correlated with both whole and soluble Zn at the 95% confidence level, indicating that Zn was the major element responsible for the oxidative damage caused by particles in Macao. Other heavy metals, such as Cr, Cu, Cd, Ni, As, and Pb, also exhibited elevated concentrations, and the potential health impacts of these metals should be considered.

Fungi are promising materials for soil metal bioextraction and thus biomining. Here, a macrofungi-based system was designed for rapid cadmium (Cd) removal from alkaline soil. The system realized directed and rapid fruiting body development for subsequent biomass harvest. The Cd removal efficiency of the system was tested through a pot culture experiment. It was found that aging of the added Cd occurred rapidly in the alkaline soil upon application. During mushroom growth, the soil solution remained considerably alkaline, though a significant reduction in soil pH was observed in both Cd treatments. Cd and dissolved organic carbon (DOC) in soil solution generally increased over time and a significant correlation between them was detected in both Cd treatments, suggesting that the mushroom‒substratum system has an outstanding ability to mobilize Cd in an alkaline environment. Meanwhile, the growth of the mushrooms was not affected relative to the control. The estimated Cd removal efficiency of the system was up to 12.3% yearly thanks to the rapid growth of the mushroom and Cd enrichment in the removable substratum. Transcriptomic analysis showed that gene expression of the fruiting body presented considerable differences between the Cd treatments and control. Annotation of the differentially expressed genes (DEGs) indicated that cell wall sorption, intracellular binding, and vacuole storage may account for the cellular Cd accumulation. In conclusion, the macrofungi-based technology designed in this study has the potential to become a standalone biotechnology with practical value in soil heavy metal removal, and continuous optimization may make the system useful for biomining.

A study was undertaken to determine the use of a plasmid DNA scission assay to evaluate the causal relationships between particle oxidative capacity and physico-chemistry. Field emission scanning electron microscopy (FESEM), image analysis (IA) and inductively coupled plasma-mass spectrometry (ICP-MS) were employed to investigate the physico-chemical characteristics of indoor PM10 (particulate matter with an aerodynamic diameter of 10 μm or less) in Beijing, China. Six PM10 samples (indoor smoker's living room; indoor non-smoker's living room and kitchen; and outdoor Beijing city; winter versus summer) were selected to represent typical indoor Beijing PM10 environments that contain high particle mass. The PM10 collected from a kitchen and two smoker's homes had the lowest TD50 (toxic dosage of PM10 causing 50% plasmid DNA damage), being as low as 45 μg ml−1 (kitchen) and 100 μg ml−1 (living room), which suggests a high oxidative capacity, with the PM10 generated in kitchens appearing to be the most toxic. The indoor PM10 from the non-smoker's home and outdoor PM10 samples demonstrated high TD50 values and were deemed less bioreactive (i.e. caused limited DNA damage). FESEM observations revealed that four types of particle species were prevalent in Beijing indoor PM10; soot aggregates, minerals, coal fly ash and unknown fine particles. IA showed that higher percentages of soot and unknown fine particles were associated with the lower TD50 values, suggesting that soot and the unknown fine particles may be important components responsible for the observed plasmid DNA damage. The water-soluble trace elements were negatively correlated with the TD50 values, implying that the DNA damage may be attributed to the water-soluble fraction of the PM10. Water-soluble zinc revealed the best relationship with the TD50 values than other analyzed elements, signifying it may play a role in driving the oxidative damage.

PM2.5 samples were collected simultaneously at three representative areas (central city, industrial area and clean air suburban) of Shanghai city. Their morphologies and elemental compositions were determined by scanning electron microscopy coupled with energy analysis (SEM-EDX). The particles were classified into four groups based on morphology and elemental composition. Soot aggregates and spherical fly ash particles were the two dominant types and they were identified as originating from automobile exhaust, metallurgical industry and coal combustion. The size distribution of the particles showed that most had diameters in the range of 0.2-1.4 mu m. Individual particles were measured by synchrotron radiation micro-beam X-ray fluorescence (micro-SXRF) and the micro-SXRF spectra were obtained. Pattern recognition techniques, which took the micro-SXRF spectrum of a single aerosol particle as its fingerprint, were used to identify the origins of the particles. Seven source types were identified. They were: metallurgical industry, vehicle exhaust, soil dust, coal combustion, diesel exhaust, oil combustion and motorcycle exhaust. Metallurgical industry, automobile exhaust, and coal combustion were recognized to be the main pollution sources Of PM2.5 in the air of Shanghai city. (c) 2006 Elsevier B.V. All rights reserved.