Remediation of Pb-polluted Agricultural Soils by Application of Biochar Amendments: Effects on Yield and Toxicological Risk Parameters in Soybean Crops

ROMINA ALEJANDRA ARIAS; BLANCO ANDRES; SHEILA DANIELA PARDO; WANNAZ EDUARDO DANIEL; MARIA JULIETA SALAZAR

Montevideo

Congreso; SETAC Latin America 15th Biennial Meeting; 2023

Society of Environmental Toxicology and Chemistry

The present work evaluated the use of biochar amendments made from peanut industry residues, using 3different pyrolysis temperatures, to remediate lead-contaminated agricultural soils. Biochar is a type oforganic amendment consisting of a stable, carbon-rich material obtained by the thermal decomposition oforganic matter. To evaluate its use for remediation in agricultural soils, an experiment was conducted undercontrolled greenhouse conditions with contaminated soils, under 4 different treatments: (1) withoutamendment, (2) with 5% biochar produced at 300°C, (3) with 5% biochar produced at 400°C and (4) with5% biochar produced at 500°C. A complete growth cycle of soybean (Glycine max (L.) Merrill) was carriedout in 9 L pots. The response variables determined included: Pb accumulation in plant organs (aciddigestion and atomic absorption spectrometry measurement), morphological state of the plants (length andplant dry weight), and yield of the produced grains (number of seeds and pods, weight of 1000 seed,aborted pods). Moreover, toxicological risk index (target hazard quotient, THQ) was evaluated forArgentinian and Chinese consumers, with the latter being one of the main destinations of Argentiniansoybean.The results showed that soybean plants grew better in amended soils, especially regarding plant length androot dry weight. The highest plant length was found in treatment (2), and the highest root dry weight wasfound in treatment (3). At the yield level, plants from all the amended treatments showed a greater numberof seeds than the not amended one, although the seed dry weight per plant and the weight of 1000 seedsdid not show differences. Pb accumulation in organs was mainly concentrated in the roots, with noremarkable differences among the treatments analyzed. It is noteworthy that the seeds showed Pbconcentrations that exceeded the limit values of international legislation for soybean consumption (circa 1.5ppm), a situation that was not reversed by the use of the amendment. In this sense, the evaluation of therisk index for consumers showed elevated values for Chinese consumers, although without an effective risk.In conclusion, the use of amendments made from peanut industry residues improved soybean developmentand yield, but it did not prevent metal accumulation in soybean seeds. For this reason, it is recommended toevaluate amendments from other sources for soybean production in agricultural soils contaminated with Pb.