Spatial distribution, food chain translocation, human health risks, and environmental thresholds of heavy metals in a maize cultivation field in the heart of China’s karst region

2022

Foods

Self Cite

Heavy metal(loid) contamination of farmland is a crucial agri−environmental problem that threatens food safety and human health. In this study, we examined the contamination levels of heavy metals (As, Pb, Cd, Hg, Cr) in farmland and foods (rice, maize, and cabbage) in the core of Asia’s largest karst region and assessed the potential health risks of consumption of these three foods. In addition, we developed a predictive transfer model of heavy metals in the soil−food chain through multiple regression equations. The results reveal that the soil heavy metals in the study area showed high accumulation characteristics, and the average concentration exceeded the national background value by 1.6−130 times, among which Cd pollution was the most serious. The order of contamination of the three soils in the study area was cabbage land > maize land > rice land. The order of potential risk of toxic elements in all three soils was Cd > Hg > As > Pb > Cr. The results of the risk assessment of agricultural consumption indicated a high carcinogenic and noncarcinogenic risk for the local population. The top contributor to carcinogenic risk was Cr, followed by As. Cd is the major noncarcinogenic contributor in maize and cabbage, and the noncarcinogenic contribution in rice is mainly caused by As. The risk was higher in children than in adults and was the highest for rice consumption. In addition, the predictive transfer model showed that the Cd levels in the three foods showed sufficient predictability and reasonable simulations of Cd concentrations in rice, maize, and cabbage throughout the study area. It could allow decision-making on the need for remediation strategies to reduce the risk of metal contamination of agricultural land in potentially high−risk areas of karst.

Section: Resultsmentioning

confidence: 99%

Characteristics, Health Risk Assessment, and Transfer Model of Heavy Metals in the Soil—Food Chain in Cultivated Land in Karst

2022

Foods

Self Cite

“…It is worth noting that the benchmark values obtained are well above the national thresholds (Table 3). These results should be attributed to the high levels of heavy metals in the soils and the low levels in the maize grains of the study area [38,53,54]. Low availability of Cd in karst soil is one of the key reasons why the Cd concentration in maize was lower in study areas with a high Cd background [55,56].…”

Section: Discussionmentioning

confidence: 99%

“…Therefore, the current standards are not fully applicable to soil evaluation in high background Cd value areas, and it is necessary to adjust the corresponding farmland soil safety limit standards based on the Cd concentrations in the edible parts of the crop products. Based on the results of a preliminary investigation of the corn planting area in Shuicheng District [38], a soil geochemical anomaly area in northwest Guizhou, in this research, a collaborative monitoring investigation with 492 pairs of soil-maize samples was carried out. The aims of the study were to (a) systematically investigation the characteristics of the accumulation and distribution of Cd in soil and edible parts of maize in the region, (b) evaluation the suitability of the current Chinese standards for the evaluation of soil Cd levels in this region, and (c) proposition a soil environmental quality benchmark of farmland soil Cd levels for Shuicheng District, Northwest Guizhou Province based on the method of species sensitivity distribution (SSD).…”

Section: Introductionmentioning

confidence: 99%

Study on Safe Usage of Agricultural Land in Typical Karst Areas Based on Cd in Soil and Maize: A Case Study of Northwestern Guizhou, China

2022

Agriculture

Self Cite

Cadmium (Cd) is an unnecessary dietary toxin that is harmful to human health. The Cd translocation in soil-crops system varies greatly depending on different soil matrices; therefore, a valuable method that could accurately evaluate soil Cd thresholds needs to be proposed immediately. In the southwestern part of China, a typical karst mountainous area of east Asia, the results of our survey of 492 soil-maize samples in the region showed high Cd accumulation in the soil, with concentrations ranging from 0.07 to 31.95 mg kg−1. The Cd concentrations in maize kernels planted in those fields, however, were quite low, and only 4 samples exceeded the national standard. A comparative study with nonkarst areas revealed a low bioaccumulation factor for soil Cd. This may be interpreted as the weathering soil-forming process of mineral-bearing rock systems, leading to high accumulation as well as low bioavailability of Cd in karst soils. A total of 172 soil-maize samples were evaluated inaccurately by the national standard evaluation procedure, accounting for 34.96% of the total. Therefore, we proposed the species sensitivity distribution model to address this inaccurate assessment. The results show that the hazardous concentrations of 95% and 5% in maize fields were 2.2 and 85.1 mg kg−1 for soil pH ≤ 5.5, 2.5 and 108.5 mg kg−1 for 5.5 < pH ≤ 6.5, and 3.0 and 161.8 mg kg−1 for 6.5 < pH ≤ 7.5, respectively. The total number of unsuitable samples according to the evaluation results decreased from 172 to 2 after modification. Therefore, this result could be considered a more accurate assessment threshold.

“…Rice is a major food crop in East and Southeast Asia, and the kernels take up, translocate and accumulate Cd in the soil and, through the dietary chain, threaten human health (Yang, Wu, & Yang, 2022). Soil Cd contamination is currently a global environmental problem that poses a potential hazard to the agro‐environment (Yang, Chen, et al, 2022).…”

Section: Introductionmentioning

confidence: 99%

Effects of rapeseed residue organic fertilizer on cadmium toxicity in soil and its uptake and transfer by rice plants (Oryza sativa L.)

Jing

et al. 2023

Land Degrad Dev

Self Cite

Cadmium (Cd) contamination of rice fields is a global agro‐environmental issue. Rapeseed (canola) residue organic fertilizer (RROF) as a potential strategy to minimize Cd accumulation in rice planted in acidic soil. The results showed that application of 7.5–30.0 g kg−1 RROF increased the soil pH value by 0.01–0.55 units, increased soil organic matter (OM) by 7.8–25.0%, increased soil microbial biomass carbon (MBC) and nitrogen (MBN) by 0.0–89.7% and 0.0–47.5%, respectively, and increased soil dehydrogenase (DH), acid phosphatase (ACP), and urease (UA) activities by 14.3–344.0%, 0.0–127.1%, and 3.5–14.3%, respectively. The application of RROF treatments reduced the soil acid‐extractable Cd (ACI–Cd) content by 8.1–36.4% and increased the reducible Cd (RED–Cd) and oxidizable Cd (OXI–Cd) by 1.3–36.4% and 16.2–47.9%, respectively. The path analysis demonstrated that soil OM, ACP activity, Mn, and Ca ions had a significant negative indirect effect on the decrease in soil ACI‐Cd (rOM = −0.628, rACP = −0.582, rMn = −0.627, rCa = −0.341), while Zn ions showed a strong direct effect (bZn = 0.567) and indirect positive effect (rZn = 0.580). In rice plants, the contents of Cd, Fe, K, Mg, P, and Zn in rice tissues increased, and the Cd content in rice grains decreased by 3.1–31.3% under RROF application. The results of the correlation analysis found that K and Zn in rice husks and Mg in grains were significantly and negatively correlated with the husk–grain translocation factor of Cd (r = −0.88** for Zn, r = −0.81** for K, and r = −0.59* for Mg). In addition, a significant negative correlation of root–straw translocation factors of Cd with Ca and Fe ions in the roots was observed (r = −0.63* and r = −0.60* for Ca at the filling and maturity stages of rice, r = −0.61* for Fe at the tillering stage of rice). RDA showed that the distribution fraction of soil Cd controlled the accumulation of Cd in various parts of rice, with soil ACI–Cd content explaining 22.4% of the total eigen values at a significant level, followed by 14.1% for OXI–Cd. This means that ACI–Cd was the primary factor that controlled Cd accumulation in rice grain, followed by OXI–Cd.