Engineered Carbonaceous Nanomaterials in Legume Agroecosystems: Potential Effects and Fates

ABSTRACT

With the pervasive presence of engineered nanomaterials (ENMs) in our society and the increasing interest in using ENMs to improve crop productivity, ENMs are predicted to enter agricultural soils. The potential hazards of ENMs in agroecosystems, including risks to food production and soil fertility, are still relatively poorly understood. My research aims to address current knowledge gaps and methodological needs in ENM hazard assessment by 1) investigating the effects of carbonaceous nanomaterials (CNMs) on a globally important legume, soybean, and its symbiotic dinitrogen (N₂) fixation in pot-scale mesocosms, and 2) developing a dispersion protocol in support of rapid ENM toxicity screening to identify particularly hazardous ENMs for prioritized further evaluation. I show that CNMs can impair soybean N₂ fixation. CNMs at lower concentrations had stronger effects because they were more dispersed in soil water and so more bioavailable than at higher concentrations. To offset inhibited N₂ fixation, soybeans shifted their N source to the soil, accompanied by changes in bean metabolite profiles. In addition to affecting soybeans cultivated under optimal conditions, CNMs can also compound damages caused by other stressors (heat and insect herbivory). Altogether, through this systematic evaluation of a plant-soil-microbial system at the process scale, I demonstrate that CNM buildup in soil could affect an important food crop and its N₂ fixation, with possible consequences to crop productivity, food quality, and soil nutrient cycling. Finally, a protocol was developed for dispersing hydrophobic ENMs to enable rapid toxicity testing. Overall, my work has advanced the ecological understanding of ENM impacts on complex plant-soil-microbial interactions that are important to agriculture, and contributed methodologies to support effective ecological risk assessment of ENMs.

BIO

Ying is broadly interested in addressing soil health and sustainable agriculture under global change. Her recent research has focused on evaluating how emerging contaminants can affect critical plant-microbe interactions in soil. Her work has been published in peer reviewed journals and presented at conferences, and has been recognized with awards from the American Chemical Society (ACS) and the Society of Environmental Toxicology and Chemistry (SETAC). Ying holds an MS and a BS both in Environmental Science from Nanjing University, China. Upon graduating from the Bren School, she will join the Lawrence Berkeley National Laboratory as a postdoctoral scholar.