Immobilization of cadmium and lead in contaminated paddy field using inorganic and organic additives

Abstract

Heavy metal contamination of agricultural soils has posed a risk to environment and human health. The present study was conducted to assess the effectiveness of soil amendments for reducing cadmium (Cd) and lead (Pb) uptake by rice (Oryza sativa L) in a contaminated field. The soil amendments used include lime, DaSan Yuan (DASY), DiKang No.1 (DEK1), biochar, Fe-biochar, Yirang, phosphorus fertilizer, (Green Stabilizing Agent) GSA-1, GSA-2, GSA-3, and GSA-4, applied at 1% rate in a field experiment. The results exposed that GSA-4 treatment showed best effects on reducing Cd and Pb phytoavailability in soil and uptake by early rice. Linear increase in pH (i.e. 5.69 to 6.75) was recorded in GSA-4 amended soil from sowing to the 3rd month of growth season. GSA-4 decreased DTPA extractable contents of cadmium (Cd) from 0.324 to 0.136 mg kg−1 soil and lead (Pb) from 53.21 to 24.68 mg kg−1 soil at 90 days of amendment. Treatment with GSA-4 improved rice growth (56%) and grains yield (42%). The enhancement effects on grain yield may be result from the positive effects of GSA-4 application on increasing photosynthesis (116%) and transpiration rate (152%) as compared to the control. Significant reduction in Cd and Pb uptake in shoot (42% and 44%) and in grains (77 and 88%), was observed, respectively in GSA-4 treatment as compared with the control. Moreover, negative correlation was recorded between DTPA extractable Cd/Pb and soil pH that directly depended on applied amendments. In short, use of combined amendment (GSA-4) was more effective for immobilizing heavy metals in contaminated paddy field, and secures rice safe production, as compared other tested amendment products.

Effective Amendments on Cadmium, Arsenic, Chromium and Lead Contaminated Paddy Soil for Rice Safety

“…Results from the principal correlation analysis revealed that Fe and Mn had a high negative correlation with Cd, As, Cr, and Pb in both plants and soil, while there was a strong positive correlation within HMs and metalloids. Our results were similar with [41,[84][85][86]. This indicates that Fe and Mn reduce the metal toxicity both in plants and soil.…”

“…The mobility of HMs were significantly decreased due to the application of lime that caused alkalinity in the soil; as a result, the precipitation and adsorption of HMs were enhanced. This adsorption and precipitation increased the stability of HMs and metalloids in soil [40,41]. Lee et al [42] used granulated lime (Ca(OH) 2 ) and calcium carbonate (CaCO 3 ) for removal of heavy metals from contaminated water and about 98% of As and 96% Cd were removed from the contaminated water through sweep precipitation.…”

Efficacy of Woodchip Biochar and Brown Coal Waste as Stable Sorbents for Abatement of Bioavailable Cadmium, Lead and Zinc in Soil

“…The use of organic sorbents as remediative agents in soil has been questioned due to claims that they could be sources of contaminants including HMs. However, unlike other studies (Hamid et al 2018;Mbarki et al 2020) which found high HM concentrations in some organic sorbents (up to 5.7 mg kg −1 Cd, 12.9 mg kg −1 Pb and 116 mg kg −1 Zn), their contents in the sorbents used in this study were much lower and within acceptable range for use in soil systems (Barth et al 2008). Figures 1, 2 and 3 show the EDTA-extractable fractions of Cd, Pb and Zn, respectively, from soils contaminated with a mixture of HMs spiked into soil at three doses.…”

Visualizing the emerging trends of biochar research and applications in 2019: a scientometric analysis and review

“…Cd and Pb have received great concern (Fig. 2) because they are the primary pollutants in agricultural soils in many countries including China and Korea (Hamid et al 2018). An increasing research interest focused on engineered biochars, supported by various methods including physical, chemical and biological modifications in 2019.…”