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Soil contamination in urban environment by trace metals is of public concerns. For better risk assessment, it is important to determine their background concentrations in urban soils. For this study, we determined the background concentrations of 9 trace metals including As, Ba, Cd, Co, Cu, Ni, Pb, Se, and Zn in 214 urban soils in Florida from two large cities (Orlando and Tampa) and 4 small cities (Clay County, Ocala, Pensacola and West Palm Beach). The objectives were to determine: 1) total concentrations of trace metals in urban soils in cities of different size; 2) compare background concentrations to Florida Soil Cleanup Target Levels (FSCTLs); and 3) determine their distribution and variability in urban soils via multivariate statistical analysis. Elemental concentrations in urban soils were variable, with Pb being the highest in 5 cities (165-552 mg kg -1 ) and Zn being the highest concentration in Tampa (1,000 mg kg -1 ). Besides, the As and Pb concentrations in some soils exceeded the FSCTL for residential sites at 2.1 mg kg -1 As and 400 mg kg -1 Pb. Among the cities, Clay County and Orlando had the lowest concentrations for most elements, with Cd, Co, and As being the lowest while Ba, Pb and Zn being the highest. Among all values, geometric means were the lowest while 95th percentile was the highest for all metals. Most 95th percentile values were 2-3 folds higher than the GM data, with Pb presenting the greatest difference, being 4 times greater than GM value (58.9 vs. 13.6 mg kg -1 ). Still they were lower than FSCTL, with As exceeding FSCTL for residential sites at 2.1 mg kg -1 . In addition, the linear discriminate analysis showed distinct separation among the cities: Ocala (Ba & Ni) and Pensacola (As & Pb) were distinctly different from each other and from other cities with higher metal concentrations. The large variations among elemental concentrations showed the importance to establish proper background concentrations of trace metals in urban soils., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Published by Elsevier Ltd.)

Lead (Pb) exposure is known to affect the health of children while soil Pb is an important contributor to human Pb exposure. To analyze the effects of both environmental and other factors, especially total and bioaccessible Pb in neighborhood soil, on school-aged urban children's blood lead level (BLL), 75 children (6-11 years old) were recruited from an industry city in eastern China for BLL measurement and questionnaire survey. Soil samples were collected from their living neighborhoods and measured for total and bioaccessible Pb. The mean BLL was 4.82 μg dL -1 , with 42 out of 75 children having BLL exceeding the international guideline of 5 μg dL -1 . Low Pb contamination was observed in soil with total Pb ranging from 12.5 to 271 mg kg -1 (mean 34.3 mg kg -1 ). Based on the in vitro Solubility Bioaccessibility Research Consortium (SBRC) gastric fluid extraction, bioaccessible Pb in soil ranged from 0.40 to 79.1 mg kg -1 (mean 7.58 mg kg -1 ) with Pb bioaccessibility ranging from 1.74 to 68.1 (mean 19.9%). When BLL was correlated with total Pb in soil, insignificant linear relationship was observed (P > 0.05, correlation coefficient 95%CI = -0.047-0.40, R 2  = 0.07). However, when BLL was correlated with soil bioaccessible Pb or Pb bioaccessibility, much stronger linear relationships were observed (P < 0.01, correlation coefficient 95%CI = 0.28-0.64, R 2  = 0.16-0.20), suggesting that bioaccessible Pb was a much stronger predictor of BLL. In addition, strong associations were also observed between BLL and social factors such as house decoration, residence time, and personal habits, suggesting that both soil Pb contamination and social factors play important roles in elevating BLL for city children., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous organic contaminants, with soil being the most important sink. This study determined the concentrations, bioaccessibility and spatial distributions of 6 emerging PAHs in Orlando and Tampa urban soils. They included 3 carcinogenic (anthanthrene, 7H-benzo[c]fluorene, and dibenzo[a,l]pyrene: 3cPAHs) and 3 non-carcinogenic (dibenzo[a,e]pyrene, dibenzo[a,i]pyrene and dibenzo[a,h]pyrene) PAHs. Based on benzo[a]pyrene-equivalent, the 7 USEPA priority cPAHs (7cPAHs) and 3cPAHs in Orlando soils averaged 452 and 7387 μg kg -1 , and Tampa soils 802 and 4943 μg kg -1 , respectively, with ∑3cPAHs being 6-16 times greater than ∑7cPAHs. Based on ArcGIS maps, the concentrations of ∑3cPAHs in commercial sites, business district and heavy-traffic areas were higher. The concentrations of ∑3cPAHs have not been reported, but they had significant impacts on risk assessment of urban soils due to their high relative potency factor. However, their bioaccessibility based on n-butanol extraction in soils of both cities were low, averaging 3.4-7.4%. Therefore, to accurately assess the risk of soils contaminated with PAHs, emerging cPAHs together with USEPA 7cPAHs and their bioaccessibility need to be considered., (Copyright © 2019. Published by Elsevier B.V.)

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous organic contaminants, which are found in soils throughout the U.S. The objective of this study was to determine the background concentrations, distributions, and sources of 16 USEPA priority PAHs in two urban soils. A total of 114 soil samples were collected from two large cities in Florida: Orlando and Tampa. The results showed that soils were dominated by high molecular weight PAHs in both cities. The average ∑16-PAHs in Orlando and Tampa soils were 3227 and 4562 μg kg -1 , respectively. The averages of 7 carcinogenic PAHs based on the benzo[a]pyrene-equivalent (BaP-EQ) concentrations in the two cities were 452 and 802 μg kg -1 . BaP-EQ concentrations in 60-62% of samples were higher than the Florida Soil Cleanup Target Level (FSCTL) for residential soils at 100 μg kg -1 and 20-25% of samples were higher than FSCTL for industrial soils at 700 μg kg -1 . Based on molecular diagnostic ratios and PMF modeling, major sources of soil PAHs in both cities were similar, mainly from pyrogenic sources including vehicle emissions, and biomass and coal combustion. Based on ArcGIS mapping, PAH concentrations in soils near business districts and high traffic roads were higher. Thus, it is important to consider background PAH concentrations in urban soils when considering soil remediation., (Published by Elsevier Ltd.)