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Research Project: Developing Technologies that Enable Growth and Profitability in the Commercial Conversion of Sugarcane, Sweet Sorghum, and Energy Beets into Sugar, Advanced Biofuels, and bioproducts-Bridging Project

Location: Commodity Utilization Research

Title: Rhizospheric pore-water content predicts the biochar-attenuated accumulation, translocation, and toxicity of cadmium to lettuce

item WANG, YI-MIN - Hohai University
item LIU, QING - Hohai University
item LI, MING - Nanjing Institute Of Environmental Sciences
item YUAN, XU-YIN - Hohai University
item Uchimiya, Sophie
item WANG, SHAO-WEI - Hohai University
item ZHANG, ZHI-YUAN - Hohai University
item JI, TAO - Hohai University
item WANG, YING - Hohai University
item ZHAO, YU-YAN - Hohai University

Submitted to: Ecotoxicology and Environmental Safety
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/15/2020
Publication Date: 12/7/2020
Citation: Wang, Y.-M., Liu, Q., Li, M., Yuan, X.-Y., Uchimiya, M., Wang, S.-W., Zhang, Z.-Y., Ji, T., Wang, Y., Zhao, Y.-Y. 2020. Rhizospheric pore-water content predicts the biochar-attenuated accumulation, translocation, and toxicity of cadmium to lettuce. Ecotoxicology and Environmental Safety. 208. Article 111675.

Interpretive Summary: Cadmium is highly mobile and easily accumulates in edible parts of food crops such as lettuce. Traditional chemical methods are too simplified to measure how much cadmium is actually taken up by the plant root, at which level cadmium becomes toxic, or how much cadmium is transported to the edible part, i.e., leaf. This study employed a dedicated method to measure available cadmium to the root. Augmentation of soil organic carbon could help mitigate adverse effects of cadmium.

Technical Abstract: Sequential extraction is traditionally used to estimate the bioavailable fraction of Cd and other heavy metal contaminants to food crops. More recently, rhizospheric porewater sampling techniques became available to account for the spatiotemporal variations of metal fractions available for the root uptake. This study compared a simplified rhizospheric Cd monitoring against a sequential extraction technique to understand how biochar influences Cd mobility in sandy/acidic and more fertile soil types. Acidic soil with low organic carbon content and low cation exchange capacity was compared with another soil of contrasting properties with and without amended organic carbon, 3% corn-straw derived biochar. After 60 days of lettuce growth at five levels of Cd (CdCl2), soil bioavailable Cd was analyzed by BCR sequential extraction and soil pore-water extraction methods. Various regression analyses were used to establish correlations between soil bioavailable Cd and its phytotoxicity in lettuce tissues. Biochar increased pH, CEC and SOM, and decreased the contents of Cd in soil pore-water (Cdpore-water) and BCR extracted bioavailable Cd (CdFi+Fii). Linear regression and pearson correlation analyses showed that soil bioavailable Cd is negatively correlated with soil properties (p < 0.05). Soil Cdpore-water was the best predictor for Cd accumulation in lettuce roots (r2 = 0.964) and in leaves (r2 = 0.953), followed by CdFi+Fii. Transfer factor (TF) values of Cd from roots to leaves were lower than 1, and better correlated with soil Cdpore-water (r = -0.672, p < 0.01) than CdFi+Fii (r = -0.615, p < 0.01). Pearson and aggregated boosted tree (ABT) analyses indicated that soil properties together with bioavailable Cd (Cdpore-water) contribute more than 50% to root enzyme activities. Collectively, soil Cdpore-water is a promising predictor of Cd bioavailability, accumulation and phytotoxicity in soil-plant system with or without biochar.