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ARS Home » Pacific West Area » Riverside, California » Agricultural Water Efficiency and Salinity Research Unit » Research » Publications at this Location » Publication #358677

Research Project: Identifying, Quantifying and Tracking Microbial Contaminants, Antibiotics and Antibiotic Resistance Genes in Order to Protect Food and Water Supplies

Location: Agricultural Water Efficiency and Salinity Research Unit

Title: Transport of biochar colloids in saturated porous media in the presence of humic substances or proteins

item YANG, WEN - China Agricultural University
item Bradford, Scott
item YANG, WANG - China Agricultural University
item SHARMA, PRABHAKAR - Nalanda University
item SHANG, JIANYING - China Agricultural University
item LI, BAOGUO - China Agricultural University

Submitted to: Environmental Pollution
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/23/2018
Publication Date: 12/28/2018
Citation: Yang, W., Bradford, S.A., Yang, W., Sharma, P., Shang, J., Li, B. 2018. Transport of biochar colloids in saturated porous media in the presence of humic substances or proteins. Environmental Pollution. 246:855-863.

Interpretive Summary: Biochar application to soils has received considerable attention as a means to store carbon, adsorb contaminants, and improve fertility, but little is known about the fate of biochar colloids (BCs) in soils. The objective of this study was to investigate the mobility of BCs in soils under different solution chemistry conditions (solution ionic strength and the pH), with special focus on dissolved organic matter (DOM). The transport of BCs was sometimes greatly enhanced by the presence of DOM. This implies that interactions between BCs and the various components of DOM should be considered before application of a biochar to a particular environment. This information will be of interest to scientists, engineers, and government agencies that are interested in applying biochar to field soils.

Technical Abstract: Application of biochar in the field has received considerable attention in recent years, but there is still little known about the fate and transport of biochar colloids (BCs) in the subsurface. Natural organic matter (NOM), which mainly consists of humic substance (HS) and proteins, is ubiquitous in the natural environment and its dissolved fraction is active and mobile. In this study, the transport of BCs in saturated porous media has been examined in the presence of two HSs (humic and fulvic acids) and two proteins. Bull serum albumin (BSA) and Cytochrome c (Cyt) were selected to present the negatively and positively charged protein, respectively. At low and high salt concentration and different pH conditions, the transport of BCs was strongly promoted by HSs. HSs significantly increased the mobility of BCs in porous media under both low and high salt conditions due to the enhanced electrostatic repulsion and modification of surface roughness and charge heterogeneity. While BC mobility in porous media was suppressed by both BSA and Cyt in the low salt solution, the presence of BSA largely promoted and Cyt slightly enhanced the transport of BCs in high salt solutions. BSA and Cyt adsorption onto BC surface decreased the negatively charge of BC and resulted in a less repulsive interaction in low salt solutions. In high salt solutions, the adsorbed BSA layers disaggregated BCs and reduced the strength of the interaction between BC and the sand. Adsorbed Cyt on BCs caused more attractive patches between BC and sand surface, and greater retention than BSA.