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

Yasir Hamid,Muhammad Zahir Aziz,Lin Tang,Muhammad Yaseen,Bilal Hussain,Xiaoe Yang,Xiaozi Wang

doi:10.1038/s41598-018-35881-8

Yasir Hamid, Muhammad Zahir Aziz + Show 5 more

Open Access

https://doi.org/10.1038/s41598-018-35881-8

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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.

Highlights

Heavy metals (HMs) enter soil environment via different anthropogenic activities e.g., smelting, mining, disposing hazardous materials and fertilization[1,2,3]
It is obvious from the results that application of organic material does not affect total Cd content but decrease Cd availability by converting exchangeable fraction to organic matter bound fraction[23]
Similar reaction might occur to biochar treatment, which reduced Cd availability from 0.324 to 0.158 mg kg−1 soil

Summary

Introduction

Heavy metals (HMs) enter soil environment via different anthropogenic activities e.g., smelting, mining, disposing hazardous materials and fertilization[1,2,3]. Overall reduction in Cd availability among the treatments decreased in the order of GSA-4 > GSA-3 > Biochar > GSA-2 > Lime > FE-BIOCAHR > Yirang > DASY > P fertilizer > GSA-1 > DEK1 > CK (0.136; 0.147; 0.158; 0.165; 0.173; 0.188; 0.188; 0.190; 0.195; 0.205; 0.224; 0.324 mg kg−1 soil, respectively). After three months of amendment, biochar decreased DTPA extractable Pb from 53.2 (control) to 24.68 mg kg−1 soil in GSA-4 treatment.

Results

Conclusion