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Potential of rice straw biochar, sulfur and ryegrass (Lolium perenne L.) in remediating soil contaminated with nickel through irrigation with untreated wastewater

PeerJ — Life and Environment Journal • 2020
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Publication Information
Authors Inas A. Hashem, Aonalah Y. Abbas, Abo El-Nasr H. Abd El-Hamed,Haythum M.S. Salem, Omr E.M. El-hosseiny, Mohamed A. Abdel-Salam,Muhammad Hamzah Saleem, Wenbing Zhou and Ronggui Hu
Keywords Rice straw biochar, Ryegrass, Nickel, Soil remediation, Sulfur, Untreated wastewater
Journal PeerJ — Life and Environment Journal
Publisher PeerJ (O
Volume Not Available
Issue Not Available
Pages Not Available
publication.type International
Paper Link Open Link
Supplementary Materials Inas Aboelnasr_peerj-08-9267-s001.xlsx
Abstract
Background
Untreated wastewater carries substantial amount of heavy metals and causes potential ecological risks to the environment, food quality, soil health and sustainable agriculture.

Methodology
In order to reduce the incidence of nickel (Ni2+) contamination in soils, two separate experiments (incubation and greenhouse) were conducted to investigate the potentials of rice straw biochar and elemental sulfur in remediating Ni2+ polluted soil due to the irrigation with wastewater. Five incubation periods (1, 7, 14, 28 and 56 days), three biochar doses (0, 10 and 20 g kg−1 of soil) and two doses of sulfur (0 and 5 g kg−1 of soil) were used in the incubation experiment then the Ni2+ was extracted from the soil and analyzed, while ryegrass seeds Lolium perenne L. (Poales: Poaceae) and the same doses of biochar and sulfur were used in the greenhouse experiment then the plants Ni2+-uptake was determined.

Results
The results of the incubation experiment revealed a dose-dependent reduction of DTPA-extractable Ni2+ in soils treated with biochar. Increasing the biochar dose from 0 g kg−1 (control) to 10 or 20 g kg−1 (treatments) decreased the DTPA-extractable Ni2+ from the soil by 24.6% and 39.4%, respectively. The application of sulfur increased the Ni2+-uptake by ryegrass plant which was used as hyper-accumulator of heavy metals in the green house experiment. However, the biochar decreased the Ni2+-uptake by the plant therefore it can be used as animal feed.

Conclusions
These results indicate that the biochar and sulfur could be applied separately to remediate the Ni2+-contaminated soils either through adsorbing the Ni2+ by biochar or increasing the Ni2+ availability by sulfur to be easily uptaken by the hyper-accumulator plant, and hence promote a sustainable agriculture.