Estimating the Possibility of Surface Soil Pollution with Atmospheric Lead Deposits Using the ADMER Model

Online in situ detection of local air conditions in hazardous operation scenarios

Although the risk of some hazardous operations has been greatly reduced, the changes in air conditions caused by them cannot be ignored. A lot of smoke is produced in some hazardous workplaces, which is very easy to cause air pollution. Exposed to this condition for a long time, human health is also greatly endangered. Therefore, the online detection of air conditions in hazardous workplaces is of great significance. In this work, electric welding operation is taken as an example to study the air conditions in hazardous workplaces. The real-time detection of smoke generated from electric welding operation is carried out by Laser induced breakdown spectroscopy (LIBS). The spectral line of lead is found in the smoke spectrum of lead tin wire. Some other metal elements are also detected in the smoke of the tin wire, such as Sn, Cu, Ca and K. Consequently, it is recommended to use lead-free tin wire. In addition, two welding scenarios are simulated. The results show that the generated smoke contains different element information with different welding objects. Then, the quantitative analysis of lead in smoke is carried out. It shows that the concentration of Pb can be calculated by the spectral line intensity in the spectrum. Finally, combined with the error back propagation artificial neural network (BP-ANN), different kinds of smoke are classified, and the recognition accuracy is more than 99%, which proves that the combination of LIBS and BP-ANN is developed into an important method in the monitoring of different air pollutants.

Screening Risk Assessment at the Production and Use Stage of Carbon Nanomaterials Generated in Hydrogen Manufacture by Methane Decomposition

We performed a screening evaluation of the human health risk posed by nanocarbon materials at the lifecycle stages of manufacturing and the use of the solid carbon generated in hydrogen manufacture by methane decomposition. We first estimated the atmospheric emission volumes of the solid carbon produced by small-, medium-, and large-scale hydrogen manufacturing plants. We then estimated the atmospheric emission due to tire wear, which largely contributes to the emission of solid carbon usage. Next, we estimated the atmospheric concentration of solid carbon in an atmospheric simulation using the METI–LIS model, which estimates the atmospheric distribution of a pollutant’s concentration near methane decomposition factories. We also used the AIST–ADMER model that estimated the regional atmospheric distributions around central Tokyo, where the traffic volume is the highest nationally. Finally, we performed a screening evaluation of human health risk in the surrounding areas, considering the permissible exposure concentrations of solid carbon. Our study identified no risk concerns at small- and medium-scale factory locations equipped with high-efficiency particulate air (HEPA) filtration facilities. At large-scale factories installed with HEPA filters, these emissions likely remain within the factory site. Furthermore, we determined that emissions from tire wear pose no risk to human health. The surroundings of small- and medium-scale factory sites installed with HEPA filters posed no risk to human health.

Settleable matter in a highly industrialized area: Chemistry and health risk assessment

Settleable particulate matter (SPM) was collected at two sampling points within an urban area highly affected by nearby industrial activities. Total deposition values up to 386 mg ·m^-2·d^-1 were registered, the majority of samples exceeding the limit value established in the legislation in force in Spain until 2002 (300 mg·m^-2·d^-1). Dry deposition values showed high variability (8.6-830.3 mg·m^-2·d^-1). Forty-one metals and metalloids were analysed in the dry fraction of SPM, the main being Fe and Ca (maximums: 304.4 and 68.6 mg·m^-2·d^-1, respectively), followed by Al, Mg, Na, K, Mn, Ti, P and Zn. Trace elements like As and Pb reached up to 7.3 and 76.3 μg· m^-2·d^-1, respectively. Strong correlations (r > 0.90, p-value < 0.05) between Fe and other elements (Ca, Mn and Pb) were found at both sampling sites. Scanning electron microscopy confirmed the presence of these particles rich in Fe and Ca, in addition to other components, whose morphologies pointed out to anthropogenic sources. These results combined with meteorology data suggest a common industrial source contributing to the levels of these metals. Furthermore, a human health risk study was carried out to assess the potential carcinogenic and non-carcinogenic risks of exposure to thirteen elements in these particles (Al, As, Cd, Co, Cu, Mn, Mo, Ni, Pb, Sb, Sr, V and Zn). The highest levels of risk seemed to be associated with the presence of As, Pb and Sb.

Clay mineralogy affects the efficiency of sewage sludge in reducing lead retention of soils

Recent studies have shown the feasibility of using of sewage sludge for the remediation of heavy metal-contaminated soils. However, there are no researches to check the influence of clay mineralogy on the efficiency of the sewage sludge to remediation of contaminated soils with heavy metals. For this purpose, we use two contrasting soils: Oxisol rich in hematite and gibbsite and Inceptisol rich in kaolinite. Thermal-treated sludge was applied to Pb-contaminated soil samples and incubated for 40 days. The soil samples were submitted to seven sequential extractions: soluble-Pb, exchangeable-Pb, precipitated-Pb, organic matter-Pb, Fe and Mn oxide-Pb, gibbsite and kaolinite-Pb, and residual-Pb. The reduction of soluble Pb forms by thermal sludge application was more pronounced in the Oxisol than in the Inceptisol because of the conversion of soluble-Pb into more stable forms, such as precipitated-Pb and oxides-Pb. For Inceptisol was necessary to apply high rates of thermal sludge to reach a significant reduction in soluble-Pb contents. The addition of humic fractions in the form of thermal sludge increased the concentration of organic matter-Pb. In confined area, the use of sewage sludge to reduce the heavy metals levels in soils must be better considered, mainly in more weathered soils.