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During the rice growth cycle, the average available cadmium concentration (C A-Cd) in the soil determines the Cd content in rice plant. Given defined soil properties and rice varieties, the meteorological factors play a crucial role in soil's available cadmium concentration (C Cd) during the rice growth cycle. Thus, it is significant to investigate the influence of meteorological factors in C Cd during the rice growth cycle and develop a predictive model for C A-Cd. The rice was cultivated under seven different sowing dates in Cd and As-contaminated soil in Hunan Province. Studied the impact of meteorological factors on paddy soil. The results showed that accumulated temperature (AT) and total precipitation (TP) were key factors affecting the soil C Cd. The correlation coefficients between AT and TP with soil C A-Cd were 0.98 and −0.94 (p < 0.01), respectively. However, there was no significant correlation with C As. AT mainly influenced the C Cd during the grouting and maturity stages. A straightforward empirical prediction model was developed, capable of accurately forecasting C A-Cd during the rice growth cycle by considering meteorological factors and the initial soil C Cd. This study supported a novel foundation for the precise prediction of Cd content in rice. [Display omitted] • AT and AP are the main meteorological factors affecting soil C A-Cd. • The first report of field experiment on the meteorological factors on the C A-Cd. • The C A-Cd prediction model was constructed based on the initial C Cd and AT, TP, ITI. [ABSTRACT FROM AUTHOR]

The paddy-crusts (PCs) play an important pole in the transformation and transfer of heavy metal in paddy. Different PCs were collected from paddy fields whose soils contained cadmium (Cd) at four concentration levels (0.61, 0.71, 1.53, and 7.08 mg/kg) in Hunan Province, China P.R. at Sep 2017. This metal's distribution among and biological community structures of PCs were both measured. Our results indicated that PCs were able to accumulate Cd from irrigation water and soil. With greater Cd levels in paddy fields, the weak EPS-binding Cd fraction decreased whereas the non-EDTA-exchangeable Cd fraction increased. The sorbed Cd fraction was initially enhanced at low-to mid-level Cd concentrations, but then gradually declined. Biomineralization was shown to function as the dominant Cd accumulation mechanism in non-EDTA-exchangeable fractions. The biological diversity of soil microbes decreased with more Cd in soil, and the Proteobacteria, Bacteroidetes, and Cyanobacteria were the dominant phyla in all the sampled PCs. Canonical correspondence analysis (CCA) between the composition of microbial communities and soil chemical variables in the PCs clustered all samples based on the Cd-contaminated level, and demonstrated that Cd, Mn, and Fe all significantly influenced the microbial communities. In particular, the Alphaproteobacteria and Chloroplast classes of bacteria may play a significant role in Cd accumulation via the bio-mineralization process. Taken together, our results provide basic empirical information to better understand the heavy metal speciation transformation mechanisms of PCs upon Cd-contaminated paddy fields. Image 1 • The PCs can accumulate heavy metals from irrigation water and soil. • Cd accumulation mainly associated with the biosorption and biogenic birnessite in PC polluted with mid- or high-level Cd. • The Alphaproteobacteria and Chloroplast might play a significant role in the accumulation of Cd in PCs. [ABSTRACT FROM AUTHOR]