Determination of Soil Cadmium Safety Thresholds for Food Production in a Rice-Crayfish Coculture System

Abstract

Previous studies have mainly focused on cadmium (Cd) contamination in conventional rice monocultures, and no research on rice-crayfish coculture has been reported. In this study, a Cd-contaminated (0–30 mg kg−1) rice-crayfish co-culture system was established by adding exogenous Cd. The results showed that the Cd concentration in each tissue of rice and each organ of crayfish increased with increasing soil Cd concentration. Specifically, the Cd concentration in each rice tissue was as follows: root > stem > leaf ≈ panicle > grain > brown rice, and the jointing and heading stages were critical periods for the rapid enrichment of Cd in the aboveground tissues of rice. The Cd concentration in each organ of crayfish was as follows: hepatopancreas > gut > gill ≈ exoskeleton > abdominal muscle. Cd was gradually enriched in the abdominal muscle after 30 days of coculture between crayfish and rice. Pearson’s correlation analysis showed that the soil’s total Cd concentration, available Cd concentration, and water Cd concentration were positively correlated with Cd content in various tissues of rice and various organs of crayfish, whereas EC and TDS in water were markedly related to rice stems, leaves, stalks, and small crayfish. According to the maximum limit of Cd in grain (0.2 mg kg−1) and crustacean aquatic products (0.5 mg kg−1) in China, the safe threshold of soil Cd for rice and crayfish under the rice-crayfish coculture system is 3.67 and 14.62 mg kg−1, respectively. Therefore, when the soil Cd concentration in the rice-crayfish coculture system exceeds 3.67 mg kg−1, the safety risk to humans through the consumption of food from this coculture system will increase. This study provides a theoretical basis for safe food production in a rice-crayfish coculture system using the established Cd pollution model.

Detection of Cadmium(II) in Aquatic Products Using a Rolling-Circle Amplification-Coupled Ratio Fluorescent Probe Based on an Aptamer–Peptide Conjugate

“…Rapid industrialization in recent years has led to increases in the use of Cd 2+ . Cadmium-containing pollutants in the aquatic environment are becoming increasingly common, exacerbating Cd 2+ contamination of aquatic products. − To regulate the market and ensure the safety of food for humans, the World Health Organization set a standard of limited detection amount of Cd 2+ in drinking water as 0.003 mg L –1 and the Chinese government has established a maximum residue limit for Cd 2+ in food (0.0001 mg L –1 for aquatic products). , However, Cd 2+ overload in aquatic products is still common. − Food has been reported to be one of the major sources of Cd 2+ exposure. Cd 2+ were detected in seaweeds, crustaceans, shellfish, and cephalopods .…”