Heavy metal poisoning has caused serious and widespread human tragedies via the food chain. To alleviate heavy metal pollution, particular attention should be paid to low accumulating vegetables and crops. In this study, the concentrations of five hazardous heavy metals (HMs), including copper (Cu), chromium (Cr), lead (Pb), cadmium (Cd), and arsenic (As) were determined from soils, vegetables, and crops near four typical mining and smelting zones. Nemerow’s synthetical pollution index (P_n), Potential ecological risk index (RI), and Geo-accumulation index (I_geo) were used to characterize the pollution degrees. The results showed that soils near mining and metal smelting zones were heavily polluted by Cu, Cd, As, and Pb. The total excessive rate followed a decreasing order of Cd (80.00%) > Cu (61.11%) > As (45.56%) > Pb (32.22%) > Cr (0.00%). Moreover, sources identification indicated that Cu, Pb, Cd, and As may originate from anthropogenic activities, while Cr may originate from parent materials. The exceeding rates of Cu, Cr, Pb, Cd, and As were 6.7%, 6.7%, 66.7%, 80.0%, and 26.7% among the vegetable and crop species, respectively. Particularly, vegetables like tomatoes, bell peppers, white radishes, and asparagus, revealed low accumulation characteristics. In addition, the hazard index (HI) for vegetables and crops of four zones was greater than 1, revealing a higher risk to the health of local children near the mine and smelter. However, the solanaceous fruit has a low-risk index (HI), indicating that it is a potentially safe vegetable type.

To examine levels, health risks, sources, and spatial distributions of potentially toxic elements in settled dust over Beijing urban area, 62 samples were collected mostly from residential building outdoor surfaces, and their <63 μm fractions were measured for 12 potentially toxic elements. The results show that V, Cr, Mn, Co, Ni, and Ba in dust are from predominantly natural sources, whereas Cu, Zn, As, Cd, Sb, and Pb mostly originate from anthropogenic sources. Exposure to these elements in dust has significant non-cancer risks to children but insignificant to adults. Cancer risks of Cr, Co, Ni, As, and Cd via inhalation and dermal contact are below the threshold of 10⁻⁶–10⁻⁴ but As via dust ingestion shows a tolerable risk. The non-cancer risks to children are contributed mainly (75%) by As, Pb, and Sb, and dominantly (92%) via dust ingestion, with relatively higher risks mainly occurring in the eastern and northeastern Beijing urban areas. Although Cd, Zn, and Cu in dust are heavily affected by anthropogenic sources, their health risks are insignificant. Source appointments suggest that coal burning emissions, the dominant source of As, are likely the largest contributors to the health risk, and traffic-related and industrial emissions are also important because they contribute most of the Pb and Sb in dust.

A total of 61 PM₁₀ samples in Huangshi (HS), Central China, were collected every sixth day from April 2012 to March 2013 and were analyzed for water-soluble inorganic ions (WSIIs) by ion chromatography. The sum of three major ions (SO₄²⁻, NO₃⁻, and NH₄⁺) accounted for 75.8% of the total WSIIs on average. The results of a non-parametric test (Kruskal-Wallis) show that, except for Na⁺ (p > 0.05), the other ions present a distinctly seasonal variation with a statistically significant difference (p < 0.05). The minimum concentrations of all ions were found in summer, while the maximum values presented in autumn (for Ca²⁺) and winter (for Cl⁻, NO₃⁻, SO₄²⁻, K⁺, NH₄⁺, Mg²⁺). Based on the highest ratio of Cl⁻/Na⁺ (3.02) and the highest concentration of K (4.37 μg·m⁻³), Ba (0.37 μg·m⁻³), and Sr (0.07 μg·m⁻³) in February 2013, it can be concluded that firework powders have aggravated the haze weather during the Spring Festival of 2013. The micro-equivalent concentrations of cations and anions were calculated and the comparisons between the calculated and measured NH₄⁺ concentrations were conducted. The results illustrate that aerosol particles in HS are acidic and there may exist some other cationic ions not detected in this study. An obvious positive correlation and good linear regression among WSIIs suggest that the chemical forms in HS aerosols show a great variety of combinations, such as NH₄NO₃, NH₄HSO₄, (NH₄)₂SO₄, NH₄Cl, KCl, KNO₃, NaCl, NaNO₃, Ca(NO₃)₂, CaSO₄, MgCl₂, Mg(NO₃)₂, and MgSO₄. The WSIIs have large positive correlation and linear regression with the elements, suggesting that WSIIs in mining cities are strongly influenced by element constituents. Principal component analysis implies that WSIIs in PM₁₀ are probably from three sources. NH₄⁺, Mg²⁺, NO₃⁻, K and K⁺, Cl⁻ and Cl, SO₄²⁻, and S accounted for 46.9% of the total variances, suggesting likely anthropogenic sources, especially coal combustion, vehicular exhaust, and biomass burning. Mg accounted for 23.3% of the total variances and Ca²⁺ and Ca explained 18.1% of the total variances, demonstrating that another important source is mineral dust from both natural and anthropogenic sources.

PM₁₀ samples were collected from Huangshi (HS) city, Central China during April 2012 to March 2013, and were analyzed for short-chain saturated dicarboxylic acids (diacids) using a capillary gas chromatograph (GC). We found that oxalic acid (C₂, 318 ± 104 ng·m⁻³) was the most abundant diacid species, followed by malonic acid (C₃, 25.4 ± 9.11 ng·m⁻³) and succinic acid (C₄, 2.09 ± 0.52 ng·m⁻³). The concentrations of C₂ and C₄ diacids were highest in winter, followed by summer and spring, and lowest in autumn. C₃ diacid was decreased in the order of summer > winter > autumn > spring. Further, the seasonal variations of WSOC (water-soluble organic carbon)- and OC (organic carbon)-normalized diacid concentrations were similar to those of diacid concentrations, suggesting that both primary emission and secondary production are important sources for diacids in Huangshi (HS) aerosols. Strong correlations were found among C₂ diacid and the three ions SO₄²⁻, NO₃⁻, and NH₄⁺ in summer and winter, suggesting that the species could undergo a similar secondary oxidation processing. C₂ had good correlation with K⁺ in summer and autumn, which indicates an enhanced contribution of combustion sources for C₂ diacid. Moreover, according to the ratio of C₂/K⁺, we can conclude that C₂ diacid should be formed by a secondary reaction of biomass combustion in HS aerosols, especially in summer and autumn. The ratios of C₂/C₄ and C₃/C₄ were compared with those reported in other sites, and the results suggest that HS aerosols should be more photochemically aged than at other urban areas. Principal component analysis of diacids and selected water-soluble inorganic ions over four seasons suggests that HS aerosols are influenced not only from primary emission, but also from secondary reaction. According to the linear relation between C₂ and C₃ diacids, the results indicate that C₂ diacid is formed from the oxidation of hydrocarbon compounds in spring, while it is from the oxidation of C₃ and C₄ diacids in summer, autumn, and winter.