Abstract
Vegetable gardens are increasingly common in urban areas and can provide numerous societal benefits; however, contamination with potential toxic elements (PTEs) due to urbanization and industrialization is cause for concern. The present study aimed to assess the source of contamination and pollution levels in urban garden soils, as well as the health risks for adults and children consuming vegetables grown in such environments. Various types of vegetable samples and their corresponding soils from 26 community gardens were collected throughout Chengdu City in southwestern China. The results showed that leafy vegetables, particularly lettuce leaves and Chinese cabbage, had relatively higher levels of Cd (0.04 mg/kg FW) and Pb (0.05 mg/kg FW), while higher levels of As (0.07 mg/kg FW), Cr (0.07 mg/kg FW), and Hg (0.003 mg/kg FW) were found in amaranths, tomatoes, and Houttuynia cordatas, respectively. The pollution indices revealed that the vegetable purplish soils were relatively more polluted by Cd and As, and the concentrations of these metals in vegetables were correlated with their concentrations in the soils. Principal component analysis grouped the PTEs in two dimensions that cumulatively explained 62.3% of their variation, and hierarchical clustering identified two distinct clusters indicating that Cr originated from a unique source. The health risk assessment revealed that exposure to As and Cd induced the greatest non-carcinogenic risk, whereas Cr was most likely to cause cancer risks. Furthermore, contaminated vegetable consumption was riskier for children than adults. The critical factors contributing to PTE contamination in vegetable gardens were determined to be vegetable species, total soil element content, soil pH, and soil organic matter content. Overall, Cr and As pollution present the greatest concern, and community health care services must enact more effective regulatory and preventative measures for urban gardens in terms of PTEs.
Highlights
Soil is considered a vital component contributing to human survival on the earth because of its role as a nutrient benefactor for plant growth; soil is anticipated to be a principal recipient of potential toxic elements (PTEs)[1,2,3]
Urban vegetable gardening is common, but exposure to PTEs originating from industrial activities or irrigation with polluted water tainted by domestic sewage or heavy traffic requires urgent attention
Higher Cd concentration was found in lettuce leaves (0.04 mg/kg FW) and Pb in Chinese cabbage (0.05 mg/kg FW), Cr in tomatoes (0.07 mg/ kg FW), As in amaranths (0.07 mg/kg FW), respectively
Summary
Soil is considered a vital component contributing to human survival on the earth because of its role as a nutrient benefactor for plant growth; soil is anticipated to be a principal recipient of potential toxic elements (PTEs)[1,2,3]. In China, pollution with toxic elements has become an increasingly serious issue, leading to increased public concern about the possible accumulation of heavy metals in agricultural soils, which poses a major threat to human health through the food c hain[3,12]. Because urban regions are often subjected to several emission sources of vegetable garden soils contamination by heavy metals is more severe and complicated. Soil acts as reservoir of toxic metals accumulation that transfer to vegetables and enter into human food chain that cause non-carcinogenic and carcinogenic health hazards due to consumption of contaminated v egetables[17,20]. The PTE concentrations in urban soil and vegetables were compared with the results of several studies conducted around the world to assess the relative pollution levels of southwest China’s urban vegetable gardens in a global context
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