Recipient Organization
UNIVERSITY OF CALIFORNIA, DAVIS
410 MRAK HALL
DAVIS,CA 95616-8671
Performing Department
Land, Air and Water Resources
Non Technical Summary
This projects supports the mission of the Agricultural Experiment Station by addresses the Hatch Act areas of soil and water conservation and sustainable agriculture.Soil amendments are utilized to improve agricultural production, remediation soil, and enhance soil health and sustainability. Amendments can be derived from a number or materials, including rocks and minerals and waste biomass. These amendments weather and release their constituents, primarily of benefits but sometimes with unintended negative consequences. Recycled organic waste (ROW) materials can be a valuable way to return nutrient to the soil, dispose of unwanted waste materials, and improve the sustainability of our agricultural systems. This project examines the co-application soil amendments (biosolids, biochar, manure, compost). While these materials can provide valuable benefits to agriculture, the presence of undesirable compounds such as heavy metals, pharmaceuticals, and polycyclic aromatic hydrocarbons can reduce their use in agriculture. It is proposed that their co-application to soil will reduce the compound bioavailability as biochar has a high potential to bind the unwanted chemicals and, in some cases, facilitate soil remediation. However, one unintended consequence of this practice may be the off-site transport of these materials via surface runoff and in dust generated from on-farm practices (e.g., tillage) which could pose risks to the surrounding environment and human population. This project will therefore conduct laboratory, mesocosm, and field experiments to evaluate the potential for transport under a range of environmental conditions and utilize chemical analysis and bioassays to determine the potential human toxicity of the transported materials.
Animal Health Component
35%
Research Effort Categories
Basic
65%
Applied
35%
Developmental
(N/A)
Goals / Objectives
Characterize abiotic and biotic processes that influence the sources, fate, transport and transformations of agrochemicals in agricultural and natural ecosystems.
Quantify and mitigate human and environmental impacts of agrochemicals.
Project Methods
A. We will examine how long-term soil processes impact the fate of contaminants when present with co-amendments, such as rock amendments (gypsum, basalt), biosolids, animal manures, and biochar. We will use soils from Campbell Tract at UC Davis, the Russell Ranch Sustainable Agriculture Facility, and various Research and Education Centers (RECs) in California. Studies will be conducted at different scales: batch reactors, mesocosm scale, and field trials. For field trials, we will take advantage of current biochar field experiments at Campbell Tracts, Russell Ranch, Kearney REC, and other locations.B. We will conduct batch sorption and incubation experiments with the following variables: biochar, rock amendment, soil, moisture content, manure, compost, biosolids and contaminants. Initial efforts will focus on soils of contrasting particle (silt loam, sandy loam) and numerous biochar feedstock (ponderosa pine, walnut shell, almond shell, etc.) produced at a range of pyrolysis temperatures with detailed analysis of both physical (e.g., surface area, porosity, and particle size) and chemical (e.g., pH, C:N:H:O, CEC) properties. Following up on previous soil remediation work using biochars to reduce heavy hydrocarbons in soils, we will examine the degradation of organic chemicals in incubations to evaluate what properties of biochars are must conducive to facilitating soil remediation.C. Concentrations of organic contaminants and heavy metals in the amendments and soil samples will be quantified via liquid chromatography mass spectrometry (LCMS) and inductively coupled (ICP) MS. Additional analyses will be conducted using Fourier transform infrared (FTIR) spectroscopy, extended X-ray absorption fine structure spectroscopy (EXAFS; for metals), LC-MS and ICPMS and, when concentrations detected are sufficiently high, relevant bioavailability will be assessed.D. Soil and amendments will be characterized to determine a range of standard physical and chemical properties. Samples will be analyzed for CEC using the standard (soil) and modified (biochar) ammonium acetate method developed in the Parikh lab, pH (1:2 w/v) solution with and without 0.01 M CaCl2, total negative surface charge (Boehm Titration) and elemental composition. Saturated paste extracts will be analyzed using inductively coupled plasma mass spectrometer (ICP-MS; Agilent Technologies7500a). C, H and N will be measured simultaneously in finely ground 1 mg samples by total combustion (Costech ECS 4010). Particle size (Beckman-Coulter LS-230), moisture content, and ash content will also be determined. In addition, BET surface area measurements will be conducted (AUTOSORB-1, Quantachrome Instruments) and mineralogy/crystallinity will be determined using X-ray Diffraction (XRD) spectroscopy (Diano XRD 8000 diffractometer). Finally, attenuated total reflectance (ATR) FTIR spectroscopy (Thermo Nicolet 6700) and Raman spectroscopy (Renishaw RM1000) will be used to examine contributions from aromatic and various functional groups (e.g., -COOH, -OH, -CH3) from the soil and biochar samples.E. Biochar content in soil and dust will be determined using benzene polycarboxylic acids (BPCAs) as specific markers to quantify biochar. BPCA can be markers of biochar because BPCA originates only from benzene rings repeatedly substituted by carbon atoms, which is a typical structural feature of biochar. The basic process involves: 1) breakup of adjacent benzene rings and 2) formation of carboxylic groups61 through the oxidation with 65% HNO3 under heated conditions. High performance liquidchromatography with diode array detector (HPLC-DAD) will be used to detect and quantify BPCA compounds.F. Bioassays will be conducted to determine if the detected compounds pose a biological risk. First, we will screen all materials (soil, biochar, biosolids, manure) using the Ames test in order to evaluate potential mutagenicity. Following the Ames test, a chemically activated luciferase expression bioassay (CALUX) will be used to determine if the biochar extracts contain compounds that have endocrine-disrupting activity; the biological activities of receptors for estrogen (ER), androgen (AR), arylhydrocarbon (AhR), and glucocorticoid/progesterone (GR/PR) will be analyzed. The CALUX bioassay is highly sensitive to trace concentrations, such as those found in environmental samples, and thus provides a quick screening test. These assays are highly sensitive to trace concentrations, such as those found in environmental samples. CALUX bioassays will be conducted based on standard methods.