Simultaneous realization of cadmium bioavailability reduction and spinach growth promotion in acidic soils with calcined oyster shells and dolomite

Abstract

Cheap and widely available calcium-based materials have gained popularity for remediating cadmium-contaminated soils, but their potential to address cadmium (Cd) toxicity in acidic soils remains deeply understudied. The current study investigated the effects of calcined oyster shells (COS) and dolomite (DM), applied at a rate of 30 g kg−1, on Cd availability and its accumulation in spinach plants in acidic Cd-contaminated soils (Cd concentration: 4.42 mg kg−1). Additionally, the influence of active aluminium (Al) on Cd bioavailability and plant Cd accumulation was examined. The application of COS and DM led to a reduction in diethylenetriaminepentaacetic acid extracted Cd (DTPA-Cd) of 42.1% and 28.6%, respectively. Furthermore, the COS and DM positively increased soil pH (2.48 and 1.81 units), electrical conductivity (89.4% and 28.1%), organic matter content (17.2% and 11.9%) and available phosphorus (37.7% and 6.39%) and decreased soil exchangeable Al3+ (100% and 83.9%). As a result of amending with COS and DM, the Cd concentration (81.0%–82.9%) and bioaccumulation factor (78.8%–80.2%) in spinach plants were significantly decreased (p