Journal
ENVIRONMENTAL POLLUTION
Volume 268, Issue -, Pages -Publisher
ELSEVIER SCI LTD
DOI: 10.1016/j.envpol.2020.115944
Keywords
Cadmium; Chemical speciation; Release kinetics; Rice; Soil amendments
Categories
Funding
- Natural Science Foundation of China [21661132001, 41671309]
- Innovative Research Team Development Plan of the Ministry of Education of China [IRT_17R56]
- Fundamental Research Funds for the Central Universities [KYT201802]
- China Scholarship Council
Ask authors/readers for more resources
The bioavailability of cadmium in paddy soils is strongly influenced by the flooding-draining cycle and amendments such as CaCO3 and CaSO4. The speciation and release kinetics of cadmium are affected by the duration of flooding and different amendments in paddy soils. Adding CaCO3 can reduce cadmium accumulation in rice plants.
Cadmium bioavailability in paddy soils is strongly affected by flooding-draining cycle. In this study, we used synchrotron-based X-ray absorption spectroscopy and a stirred-flow method to investigate the effects of flooding-draining and amendments of CaCO3 and CaSO4 on Cd speciation and release kinetics from a Cd-spiked paddy soil (total Cd concentration of 165 mg kg(-1)). Extended X-ray absorption fine structure analysis showed that Cd was predominantly bound to non-iron-clay minerals (e.g. Cd-kaolinite, Cd-illite, and Cd-montmorillonite, accounting for 60-100%) in the air-dried soil and 1- or 7-day flooded samples. After prolonged flooding (30 and 120 days), Cd-iron mineral complexes (e.g. Cd bound to ferrihydrite and goethite) became the predominant species (accounting for 52-100%). Stirred-flow kinetic analysis showed that both prolonged flooding and the amendments with CaCO3 and CaSO4 decreased the maximum amount and the rate coefficient of Cd release. However, the effect of prolonged flooding was reversed after a short period of draining, indicating that although Cd was immobilized during flooding, it became mobile rapidly after the soil was drained, possibly due to pH decrease and rapid oxidation of CdS. The effects of the amendments on Cd uptake in rice plants were tested in a pot experiment using the same paddy soil without Cd spiking (total Cd 2.1 mg kg(-1)). Amendment with CaCO3 and, to a lesser extent, CaSO4, decreased the Cd accumulation in two cultivars of rice. The combination of CaCO3 amendment and a low Cd accumulating cultivar was effective at limiting grain Cd concentration to below the 0.2 mg kg(-1) limit. (C) 2020 Elsevier Ltd. All rights reserved.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available