Background: Copper (Cu) and zinc (Zn) are essential nutrients that must be maintained at adequate levels in the human body in order to make physiological functions normal and sustainable. Rice is a leading staple cereal crop which can be the main source of Cu and Zn in the diet. Results: Here, we aimed to investigate Cu and Zn concentrations in rice with corresponding soil influencing factors and to assess the dietary intake of Cu and Zn from rice consumption by residents of major rice producing regions. A total of 712 rice grain and 90 paired soil–rice samples were collected from September to November 2015 covering eleven provinces across China. Average Cu and Zn concentrations were 27.2 and 69.1 mg kg⁻¹, respectively, in soils, and 1.98 and 12.3 mg kg⁻¹ in rice. The concentrations and bioconcentration factors (BCFs) of Cu and Zn followed the sequence: roots > shoots > grains. Soil pH, cation exchange capacity (CEC), and soil organic carbon (SOC) play important roles in rice Cu and Zn uptake with negative effects. The average Cu and Zn intakes from rice consumption were 0.597 and 3.68 mg day⁻¹, respectively. Conclusions: The status of Cu and Zn daily intake from rice consumption were fully adequate but there remained some sampling sites where Zn intake for males and Cu intakes were deficient at 1.40%, indicating that local residents need to maintain their dietary nutrient requirements.

Heavy metal pollution in agricultural soil has been tightly associated with anthropogenic emissions. Although there are many studies that focus on a regional scale, the source identification of heavy metal contamination on a field scale around industrial areas remains unclear. The average concentrations in topsoils of Hg, Cd, As, Pb, Cr, Ni, Zn, and Cu were 2.07, 0.13, 8.56, 42.3, 81.1, 37.3, 105, and 43.8 mg kg⁻¹, respectively. The enrichment of Hg was particularly presented on topsoils, with the highest single pollution index (Pi) (9.00) and ecological risk index (Eri) (922) values. An integrated methodology was employed in source identification of heavy metals contamination, especially for Hg, including Pearson’s and PCA analysis, soil profile morphology, mathematical modeling, and Hg isotope analysis. Results revealed that the concentrations of Hg decreased as a function of depth, suggesting Hg contamination was an anthropogenic source and can be supported by Hg isotope analysis. The negative Δ¹⁹⁹Hg values of the residual Hg (F4-Hg) and soil profile in 80–100 cm deviate from those of the soil profiles in 0–80 cm, indicating exogenous input of Hg occurred in the study area. According to the UNMIX model, the contribution of coal combustion, agricultural activities, parent material, and industrial/traffic emissions to Hg accumulation in soils were 66.2%, 16.9%, 9.81%, and 7.0%, respectively. However, the contribution rates calculated with the PMF model of mixed industrial source, traffic emissions, and parent material were 71.4%, 27.8%, and 0.8%, respectively. This study can accurately quantify and identify the factors contributing to heavy metal contamination in agricultural soil on a field scale.

Soil microbial communities are essential for the natural attenuation of organic pollutants, yet their ecological responses under long-term contamination remain insufficiently understood. This study examined the bacterial community structure and the abundance of dechlorinating bacteria at a decommissioned pharmaceutical-chemical site in northern Jiangsu Province, China, where the primary pollutants were dichloromethane, 1,2-dichloroethane, and toluene. Eighteen soil samples from the surface (0.2 m) and deep (2.2 m) layers were collected using a Geoprobe-7822DT system and analyzed for physicochemical properties and microbial composition via 16S rRNA gene amplicon sequencing. The results showed that the bacterial community composition was significantly shaped by the soil pH, moisture content, pollutant type, and depth. Dechlorinating bacteria were detected at all sites but exhibited low relative abundance, with higher concentrations in the surface soils. Desulfuromonas, Desulfitobacterium, and Desulfovibrio were the dominant dechlorinators, while Dehalococcoides appeared only in the deep soils. A network analysis revealed positive correlations between the dechlorinators and BTEX-degrading and fermentative taxa, indicating potential cooperative interactions in pollutant degradation. However, the low abundance of dechlorinators suggests that the intrinsic bioremediation capacity is limited. These findings provide new insights into microbial ecology under complex organic pollution, and support the need for integrated remediation strategies that enhance microbial functional potential in legacy-contaminated soils.