Geochemical fractionation study in combination with equilibrium based chemical speciation modelling of Cd in finer sediments provide a better description of Cd bioavailability in tropical estuarine systems

• Published in: The Science of the total environment 2021-04, Vol.764, p.143798-143798, Article 143798
• Main Authors: Ramteke, Darwin, Chakraborty, Parthasarathi, Chennuri, Kartheek, Sarkar, Arindam
• Format: Article
• Language: English
• Subjects: Cd bioaccumulation; Cd speciation; Edible oyster contamination; Geochemical fractionation; Metals in mangrove sediment; Visual MINTEQ
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2020.143798

Geochemical fractionation study of cadmium (Cd) in combination with equilibrium based chemical speciation modelling (visual MINTEQ) in finer sediment samples (silt and clay portion), provided a better description of Cd bioavailability for sessile organisms (like oysters) in the Zuari estuary, west coast of India. A substantial fraction of total Cd in the finer sediment samples was present as water soluble, exchangeable and carbonate/bicarbonate forms and showed a strong positive relationship with Cd-bioaccumulation in oysters (Magallana sp.) from the study area. Cadmium bioaccumulation (ranged from 2.4–7.9 mg·kg−1) in soft tissues of the edible oyster was high (higher than the maximum permissible limit for human consumption) throughout the study period of one year. Equilibrium based speciation modelling suggest that sedimentary CdCl2, CdCl+ and Cd2+ were responsible for Cd bioaccumulation in the oysters. This study describes that combination of geochemical fractionation study of metals in finer sediments and equilibrium based speciation modelling can be very useful in comprehending link between sedimentary metal speciation and its bioaccumulation in sessile organisms. [Display omitted] •Cd-bioaccumulation in oyster depend on Cd speciation in finer sediments.•Sequential extraction and speciation modelling can pinpoint bioavailable Cd species.•Sedimentary CdCl2, CdCl+ and Cd2+ were responsible for Cd-bioaccumulation in oysters.•Cd concentration in oyster was higher than permissible limit for human consumption.