Edta, Water-Extractable Arsenic and Bioavailability of Arsenic in Soil/Tailings: the Effects of Zeolite and Beringite Amendments

Abstract

The effects of zeolite and beringite ( 0, 30 and 60 kg ha^-1 w/w) on EDTA-extractable Arsenic (As), water soluble As, and bioavailability of arsenic (As) in non-mined agricultural soil and tailings of a mined site(capped and uncapped) were studied in a pot experiment. Un-amended non-mined agricultural soil was included as a control. EDTA-extractable and water extractable forms of As were monitored for 0-12-weeks after amendments and bioavailability of As was evaluated by growing lettuce (Lactuca sativa) on amended tailings/soil for 4-12 weeks after incubation. For EDTA-extractable As at week 12, beringite amendment (60 kg ha^-1 (w/w) was 29 %, 8.6 % and 26 % more efficient over zeolite for soil/capped and uncapped tailings respectively. For water-extractable As at week 12, beringite amendment 60 kg ha^-1 (w/w) again recorded 84 %, 54.5 % and 72 % less extractable As over zeolite in soil/capped and uncapped tailings respectively. Analysis for bioavailable-As in edible leafy aerial parts of lettuce, indicated 52.5 %, 82.0 % and 39.0 % less extractable As for beringte over zeolite in capped and uncapped tailings (week 12, 60 kg ha^-1 (w/w)... Beringite (week 12, 60 kg ha^-1 w/w) reduced As of capped tailing (0.3 mg kg^-1) below the FAO & WHO recommended maximum limit of 1.0 mg kg^-1 for human consumption.