[Response of Cadmium in Soil-rice to Different Conditioners Based on Field Trials].

A plot experiment was carried out to assess the applicability of soil conditioners on Cd-polluted acidic paddy fields. The effects of five soil conditioners[Tianxiang 1 Hao (TX1), limestone (Li), silicon fertilizer, Nuodikang (NDK), and calcium magnesium phosphate fertilizer (CaMg-P)] on Cd accumulation and transport between contaminated soil and rice plants and rice yield on the land were analyzed. The results showed that compared with that under the control, other tested methods increased soil pH by 0.41-0.68 units and decreased available Cd content in the soil by 11.2%-39.7%. The difference between Li- and NDK-treated soil available Cd reached a significant level (P < 0.05). ② Compared with that in the blank control, the application of soil conditioner could significantly reduce the total amount of Cd in rice, and the Cd content in roots, other leaves, rachises, chaffs, and brown rice were significantly lower than those in the CK treatment (P < 0.05). The Cd translation factor between various sites was shown as TFroots-other nodes > TFroots-first nodes > TFroots-rachises > TFroots-chaffs ≈ TFroots-flag leaves > TFroots-brown rice. The Cd content of brown rice met the national safety standard (0.2 mg·kg-1), in which the TX1, Li, and CaMg-P treatments showed significant Cd reduction effects, and ω(Cd) was 0.097, 0.094, and 0.134 mg·kg-1, respectively. ③ The application of soil conditioner could increase the yield by 9.9%-35.8%, and the yield of the CaMg-P and TX1 treatments was significantly higher than that of other treatments (P < 0.05). ④ Correlation analysis showed that the Cd content in brown rice was significantly positively correlated with available Cd content in soil, available Fe content in soil, and available phosphorus but negatively correlated with soil pH. In summary, TX1 and CaMg-P are recommended to be applied in farmland lightly polluted by the heavy metal Cd to ensure the safety of agricultural products.

[Low Accumulation Characteristics of Sweet-waxy Maize in Pb and Cd Complex Contaminated Soils Based on Field Trials].

To screen out sweet-waxy maize varieties with low accumulation characteristics suitable for planting in lead (Pb) and cadmium (Cd) complex contaminated soils, 39 maize varieties were selected, and the enrichment characteristics and differences of grains and straws on Pb and Cd were studied through field trials. Maize yield, bioaccumulation factors, and soil Pb and Cd risk thresholds were used as evaluation indicators for screening low accumulation maize varieties. The results showed that there were significant differences between the yield and Pb and Cd contents in grains and straws of different varieties of maize (P<0.05). Bioaccumulation factors of grains for Pb and Cd were in the range of 0.00003-0.00230 and 0.01-0.15, respectively, and those of straws for Pb and Cd were in the range of 0.003-0.065 and 0.64-4.28, respectively. Through the cluster analysis of bioaccumulation factors, the soil Pb and Cd risk thresholds of different varieties of maize were comprehensively obtained:Huitian 5, Xinmeitian 818, and Yunuo 9 could be safely produced in the farmland with Pb and Cd content exceeding the risk control value, and Tianguinuo 937 and Jinwannuo 2000 could be safely produced in the farmland with Cd content exceeding the risk screening value. Huitian 5, Xinmeitian 818, and Yunuo 9, as low Pb and Cd accumulation varieties, were suitable to be popularized on Pb and Cd polluted soil in Guangxi, China. Tianguinuo 937 and Jinwannuo 2000, as low grain and high Cd accumulation varieties, are suggested to be used as phytoremediation resources.

[Accumulation Effects and Health Risks of Heavy Metals in Rice in Location-based Cadmium Anomaly Area in Liuzhou].

In order to explore the migration and transformation characteristics of soil heavy metals in rice in an area of ground source cadmium anomaly and to evaluate the safe planting of rice, a total of 91 pairs of soil and rice samples were collected from paddy fields in the typical area of Liuzhou city, Guangxi province, and the contents of heavy metals such as Cd, soil pH, and organic matter were tested. The results showed that:① Cd, Cu, Ni, and Zn in the paddy field exceeded the background values of 92.31%, 34.07%, 36.26%, and 90.11%, respectively. Compared with the screening values in the Soil Environmental Quality Agricultural Land Soil Pollution Risk Control Standard, Cd and Zn exceeded 30.53% and 25.26%, respectively. Super standard points were mainly distributed in Fushi Town. ② Cd and Ni exceeded 35.16% and 3.30%, respectively, and Daliang town had the highest Cd enrichment coefficient and Cd exceeded rate. ③ Correlation analysis showed that soil pH was the main influencing factor of heavy metals in rice, and Cd and Ni had similar pollution sources in rice. ④ The results of rice health risk assessment showed that the THQ value of rice Cd in Daliang town was greater than 1.0, indicating the potential health risk of rice Cd in this area. The TTHQ values were all greater than 1.0, indicating that the risks to children were higher than those to adult women, which were higher than those of adult men, showing that reasonable dietary structure is crucial to prevent heavy metal intake in different ages and genders. Therefore, there are certain risks in rice planting in the Liuzhou area of ground source cadmium anomaly, which need to be controlled using different safety utilization measures.