Biochar-Dual Oxidant Composite Particles Alleviate the Oxidative Stress of Phenolic Acid on Tomato Seed Germination.

Phenolic acid is a well-known allelochemical, but also a pollutant in soil and water impeding crop production. Biochar is a multifunctional material widely used to mitigate the phenolic acids allelopathic effect. However, phenolic acid absorbed by biochar can still be released. In order to improve the removal efficiency of phenolic acids by biochar, the biochar-dual oxidant (BDO) composite particles were synthesized in this study, and the underlying mechanism of the BDO particles in ameliorating p-coumaric acid (p-CA) oxidative damage to tomato seed germination was revealed. Upon p-CA treatment, the BDO composite particles application increased the radical length, radical surface area, and germination index by 95.0%, 52.8%, and 114.6%, respectively. Compared to using biochar or oxidants alone, the BDO particles addition resulted in a higher removal rate of p-CA and produced more O2•-, HO•, SO4•- and 1O2 radicals via autocatalytic action, suggesting that BDO particles removed phenolic acid by both adsorption and free radical oxidation. The addition of BDO particles maintained the levels of the antioxidant enzyme activity close to the control, and reduced the malondialdehyde and H2O2 by 49.7% and 49.5%, compared to the p-CA treatment. Integrative metabolomic and transcriptomic analyses revealed that 14 key metabolites and 62 genes were involved in phenylalanine and linoleic acid metabolism, which increased dramatically under p-CA stress but down-regulated with the addition of BDO particles. This study proved that the use of BDO composite particles could alleviate the oxidative stress of phenolic acid on tomato seeds. The findings will provide unprecedented insights into the application and mechanism of such composite particles as continuous cropping soil conditioners.

[Experimental study on prediction model for leachate quality variation in MSW landfills].

The changing rule of leachate quality in Xiaping Sanitary Landfill was studied using pilot-scale leaching test for waste pollutants. And the parameters for Pollutants Leaching Model were determined using the data from the test by exponential regression method. Both the results from the test and the monitoring data in site indicated that the leachate concentration reached its maximum with COD of 31,581 mg/L after 75 days. Meanwhile, the accuracy of this prediction model was testified by comparing with the monitoring data in site, that means the model and its parameters achieved by leaching test for pollutants load can be used to predict the leachate quality variation in MSW landfills. Thus it provides a scientific numerical model and leaching test method for leachate quality prediction and basis for designing and managing leachate treatment facilities.