Newsletter - Winter 2011
Current Research - Landscape Processes
Sanjai Parikh Lab, October 2010
Research in the Sanjai Parikh lab is focused on investigating the many different interfacial processes occurring on soil surfaces and their role on transport and fate of environmental contaminants. Current research efforts in the lab include studies examining antibiotic transport in soil and groundwater from range and dairy settings, C and N cycling in soils receiving biochar soil amendments, the effects of irrigation using recycled winery effluent on soil properties and vine health, and the specific soil physical and chemical parameters which correlate to soil survey map units for forensic investigations.
Graduate students Daniel Bair, Sarah Hafner, Brian Mathison and Lina Bachert are conducting research to address the fate and transport of antibiotics in the environment. This is of particular interest as antibiotics are used in livestock production for treatment of disease and for growth promotion. Up to 75% of administered antibiotics are believed to be excreted unaltered in waste making the manure an environmental source of both antibiotics and genetic resistance determinants. These studies aim to quantify sorption of various antibiotics (e.g., monensin, sulfamethazine, oxytetracycline, ivermectin) to soil and mineral phases. In addition possible abiotic degradation pathways via Mn- and Fe-oixide minerals are being determined. The Parikh lab is Collaborating with Ken Tate and Thomas Harter on various projects related to antibiotic transport in the Central Valley.
Maya Buelow is focused on identifying relationships between the composition of treated winery wastewater, which is applied to vineyards, and soil chemical and physical characteristics at wineries in Northern and Central California (collaboration with Kerri Steenwerth). Adequate soil levels of potassium are necessary for enhancing grape color and sufficient acidity and to ensure this, vineyards typically add potassium to their irrigation water. However, not much investigation has been done on what effect this potassium enriched irrigation water has on soil properties and grape vine health. She will also investigate how winery cleaning procedures, using sodium (Na)-and potassium (K)-based cleaners, affect irrigation water chemistry and to determine how this influences young grapevines and soils of contrasting mineralogy receiving the treated wastewater through a series of greenhouse and laboratory based studies. Also of interest is how shifts in wastewater composition, especially enrichment in potassium due to use of potassium-based cleaning chemistry in the winery, will influence mature vine growth in Northern California vineyards.
Soil science is also important in forensic science where two types of questions are often posed when soil samples are involved. The first is comparative, which involves trying to connect a suspect to the crime scene using soil found on the suspect’s belongings and the second is investigative, trying to identify the location from which a sample originated. Currently there is a dearth of information to answer the latter question and this is the primary goal of Melissa Suarez’s research. Several physical, mineralogical and chemical techniques including particle size analysis, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and sequential chemical extractions will be used on soils collected from Fallbrook sandy loam map units (5 locations) and adjacent map units (3 locations) in Riverside and San Diego County.
Dr. Fungai Mukome (Postdoctoral Scholar) is investigating the effect of biochar soil amendments on carbon and nitrogen biogeochemistry (collaboration with Johan Six). Biochar is produced during the low temperature pyrolysis of organic residues (plant matter, animal waste) to generate renewable energy. Since the discovery of the Terra Preta de Indio (Indian Black Earth) soils in the Amazon, the use of biochar amendments to agricultural soils is receiving increased attention as a method for reducing N leakage while sequestering carbon, improving soil fertility, and increasing water retention in soil. Dr. Mukome’s is conducting careful characterization of biochars from different feedstock and produced under varied pyrolysis conditions and also evaluating their influence on soil greenhouse gas emissions. His research will help to answer some fundamental questions the role of biochar on soil N-cycles and C sequestration and its use in agriculture.
Parikh Lab, October 2010:
PhD Students: Danny Bair, Sarah Hafner
MS Students: Maya Buelow, Brian Mathison, Lina Bachert, Melissa Suarez
Undergrad Students: Ellen Zhang, Allie Jefferson
Staff Research Associate: Chris Alaimo