Characteristics And Mitigation Strategies Of Heavy Metal Pollution In Rice Based On Ionomics

Under the influence of industrial and mining activities and agricultural activities,the heavy metal pollution of cultivated land is becoming more and more serious,and the accumulation of heavy metals in rice fields will affect human health through the food chain.When rice is polluted by various heavy metals,it is not only affected by a single element,but also co-regulated by other ions with significant correlation.In this study,the pollution characteristics of rice were studied by collecting rice samples around Changsha,and the comprehensive regulation of heavy metal pollution in rice was carried out through hydroponic cultivation experiments and cooking experiments.The main conclusions are as follows:(1)Study on the characteristics of heavy metal pollution in rice system based on ionomicsThe heavy metal content in the rice and paddy soil around the Changsha rice planting area and the Zhuzhou lead-zinc mining area was collected and measured,and it was found that there was significant cadmium pollution in the Zhuzhou soil.The arsenic in the Changsha brown rice sample and the cadmium and mercury in the Zhuzhou brown rice sample exceeded the national standard requirements,and there was significant pollution..For different tissues of rice,the distribution of elements showed different patterns.For example,the roots of rice had a strong ability to accumulate elements such as cadmium,arsenic,and lead,while elements such as manganese,zinc,and barium were more transported to stems and leaves.Principal component analysis found that the absorption and transport of cadmium by rice were related to copper,zinc,manganese and other elements,indicating that the ionomic analysis method was more sensitive to changes in environmental factors.(2)Front-end regulating ions reduce the enrichment of heavy metal pollution-taking Cd as an exampleBy adding 0.5 mg/L of copper,zinc and manganese to the culture medium to regulate the uptake and transport of cadmium by two different rice varieties,Fenghuazhan and Huanghuazhan,it was found that the cadmium content in the roots of the two rice varieties was Cd++Manganese group>cadmium group>cadmium+zinc group>cadmium+copper group>control group;the content of cadmium in the treatment group added with zinc and manganese in stems and leaves was higher than that in other treatment groups.For biomass,Fenghuazhan rice was significantly better than Huanghuazhan rice in biomass,and copper added had the strongest inhibitory effect on rice growth.The absorption and transport of cadmium,copper,zinc and manganese have both competition and synergy.The process is regulated by various factors such as ionic environment and rice varieties,and copper is dominant in the competition.Therefore,it is feasible to adjust the cadmium content in rice by changing the copper,zinc,and manganese in the growth environment,but precise dosage is required during the addition process to avoid new pollution.(3)End-treatment procedures reduce the bioavailability of heavy metal pollutionIn view of the heavy metal pollution in rice,the effect of different treatment methods on reducing the bioavailability of heavy metals in rice was investigated.The content of heavy metals in polished rice from Hunan Province and Northeast China was collected and determined.The average content of copper and cadmium in Hunan rice was higher than that in Northeast rice,but there were more extreme values in Hunan rice,and there were samples of arsenic and cadmium exceeding the standard.The effects of cooking water ratio and pre-soaking on the total amount of heavy metals in rice were investigated,and it was found that the 30-min soaking process could significantly reduce the contents of mercury,iron and cobalt in rice.The PBET analysis of the samples showed that the bioavailability of cadmium,copper,zinc and manganese in rice increased and the bioavailability of arsenic decreased after soaking for 30 min.According to the correlation analysis,appropriate addition of food or additives containing Ti and Zn can reduce the absorption of cadmium and arsenic by the human body.