Risk assessment and prediction for toxic heavy metals in chestnut and growth soil from China

Abstract

BACKGROUND Toxic heavy metals (THMs) cause severe environmental hazards and threaten human health through various consumption of food stuff. However, little is known of THMs in chestnuts. In this study, the risk assessment and prediction of THMs [lead (Pb), arsenic (As), chromium (Cr), cadmium (Cd) and mercury (Hg)] in chestnuts and growth soils from China were investigated. RESULTS The main detected THMs in chestnuts and growth soils were As and Cd. The total pollution levels of the five THMs (Nemerow pollution indexes, NPIs) were 0.062 and 1.06, respectively. The dietary risks for children were higher than those of adults, especially short‐term non‐carcinogenic risk. The main combined risks from the relationships between THMs were Pb‐Cr (r = 0.85, P < 0.01) in chestnuts and Pb‐As (r = 0.59, P < 0.01) in growth soils. The risk source was found to be the uptake effect of THMs from soil to chestnut, with the highest bioaccumulation factors (BCFs) of Cd (0.254). Several comprehensive risk models were established with the highest coefficient of determination (R2) of 0.79. In addition, the main contribution rates of different soil parameters to comprehensive risk of THMs uptake were 49.8% (Cd), 23.4% (pH), 13.8% (Cr) and 13.0% (organic carbon). CONCLUSION The total pollution levels of THMs fell outside of the safety domain in growth soils. Furthermore, more attention needs to be paid to Cd pollution owing to its low environment background value and high accumulation ability. Three main soil parameters (Cr content, pH, organic carbon) played important roles in the formations and accumulations of THMs in chestnuts. © 2019 Society of Chemical Industry

A risk‐based approach for the safety analysis of eight trace elements in Chinese flowering cabbage (Brassica parachinensis L.) in China

“…33 This was performed after acid digestion of 0.2 g soil for 4.5 h using a mixture of concentrated HNO 3 + H-ClO 4 + HF (6.4 + 1.6 + 4 mL) in a covered Teflon crucible with a temperature-controlled graphite digester (DigiBlock ED54; Lab-Tech, Shanghai, China) with the temperature gradually increased to 120°C for 0.5 h, 150°C for 0.5 h and 210°C for 2.5 h. For the total As and Hg concentrations, 0.25 g of soil was added to colorimetric tubes with stoppers and digested with a mixture of concentrated HCl:HNO 3 :H 2 O (3:1:4, 10 mL) in a water bath (100°C) for 2 h and then subjected to atomic fluorescence spectrometry (AFS) (AFS-9130, Jitian Instruments Co. Ltd, Beijing, China). 9 The available concentrations of Cr, Cd, Pb, Ni, Cu, Zn, As and Hg were determined by 10.0 g of soil with 100 mL of 0.01 mol L -1 CaCl 2 in centrifuge tubes. 34 Samples were placed on a horizontal shaker revolving at 180 times min −1 for 120 min in a room at a constant temperature of 20 ± 2°C.…”

“…11,14 BCF is the ratio of TE concentration in different parts of the plant to that in the soil, and it determines the degree of plant TE uptake from the soil. 3,9 TF is the ratio of TE in the aboveground part to that in the underground part, which is an important indicator for measuring the distribution and transportation of TEs in plants. 17 Higher values of BCF and TE indicate the greater potential of plants to transfer TEs from the soil to the food chain.…”

“…Soil pH is commonly considered a major factor in extractable soil TE concentrations and vegetable TE accumulation because it controls metal speciation, solubility and mobility in the soil metal pool, and a low soil pH usually facilitates TE bioavailability. 9,54 Taking the total TE concentrations as the soil thresholds, soil pH significantly contributed to the regression model fit for Cd transfer in soil-crop systems. 28,59 The total soil TEs should be combined with soil pH to be reasonably predictive of TE concentrations in aboveground plant tissue.…”

“…8 Therefore, the scientific assessment of TE uptake and accumulation characteristics of vegetables from the soil is necessary for the safe production of crops and evaluation of soil quality. 9,10 As China has rapidly transitioned from a traditionally agricultural-based economy to an industrial and technologybased economy over the last 30 years, increasing contaminant levels are threatening agricultural soil, especially in South China where there is also increasing soil acidification. 11 This combination could heighten the risk of TE accumulation in food and subsequently endanger human health.…”

Food safety considerations of urban agroforestry systems grown in contaminated environments

“…However, studies of Chinese chestnut [Ca. henryi (Skan) Rehder & E. H. Wilson] cultivated on nonurban HM-contaminated soils found that Cd and Pb concentrations in edible parts of the nut exceeded the safety limits and were not safe for human consumption (Li et al, 2007;Wu et al, 2019). The number of studies specifically exploring the accumulation of toxic substances in edible nuts and fruits are limited, and more research is clearly needed before specific recommendations might be made.…”