Céline Pallud, Professor

Closed (1) Biotic and abiotic oxidation of selenium nanoparticles

Applications for Fall 2017 are now closed for this project.

Selenium (Se) is a geochemically complex redox-sensitive element playing an important role in modern and ancient environments. Se is known as an “essential toxin” due to its biological importance and toxic effects on living organisms in a narrow concentration range. It has recently emerged as an environmental contaminant detrimental to aquatic wildlife at elevated concentration. In natural settings, Se occurs in four oxidation states (VI, IV, 0, -II), each displaying differing solubility and sorption characteristics. In the environment, several biotic and abiotic processes catalyze Se redox transformations. Among them, reduction of Se-oxyanion has been extensively studied for both microbial and abiotic Se pathways, whereas Se oxidation is not as well understood. Although Se oxidation is an important process for controlling Se biogeochemical cycle in natural settings, and has been a major Se mobilizing process throughout the geologic history very little is known about the biotic and abiotic oxidation of Se(0). Hence, the major objective of the project is to investigate the rate of abiotic and biotic oxidation of Se(0) in presence of various chemical oxidants.


Step I: Chemical synthesis and purification of Se(0) nanoparticles by reducing Se(IV) for Se(0) oxidation study.
Step II: Abiotic oxidation of Se(0) experiments with three different oxidants (e.g. MnO2, KMnO4 and Fe(III)) will be conducted. Soluble Se concentrations will be measured using ICP-OES.
Step III: Two different bacteria will be used to study the biotic oxidation of Se(0). Samples will be collected and measured by ICP-OES to quantify dissolved Se produced due to biotic oxidation of Se(0).


The student will be trained in microbiology methods, including working in sterile conditions, preparing culture media, maintaining pure cultures, studying bacterial growth curve and rate of biotic oxidation of Se(0).

Day-to-day supervisor for this project: Joyabrata Mal, Post-Doc

Weekly Hours: to be negotiated

Related website: celinepallud.com

Closed (2) Comparing the effects of chemical and organic fertilization on soil quality and plant yield in tomato cropping systems

Closed. This professor is continuing with Spring 2017 apprentices on this project; no new apprentices needed for Fall 2017.

Chemical fertilizers and pesticides are commonly used in industrial and small-scale agriculture. Application of synthetic fertilizers, can lead to increased insect pest densities, decreased soil quality, and runoff of nutrients that harm neighboring ecosystems. Our project seeks to evaluate the effects of organic agricultural treatments (composts and compost teas) compared to conventional agriculture (chemical fertilizer). Compost tea is a solution leached from a mixture of water, compost, manure, sugars and proteins that is used both as an organic fertilizer and pesticide. More specifically, by combining a field-scale study using tomato plants, and laboratory microbiological work on the soil, this project will investigate the effects of compost and compost tea applications on improving soil quality as well as plant health and productivity.
We will compare the effects of compost tea and of chemical fertilizer application on both plant health and soil health. The field study will be performed at the UC Berkeley Gill Tract where tomato plants will be receiving different treatments. More specifically, we will compare the effects of (i) compost tea application to the soil, (ii) compost tea application to the foliage, (iii) chemical fertilizer application to the soil and (iv) no treatment (control).

We will measure the effects on:
1. Plant health
- Plant vigor (health and size)
- Tomato fruit production
- Tomato fruit quality (sugar content)
2. Soil health
- Abundance of total bacteria in soil
- Abundance of phosphorus-solubilizing rhizobacteria
- Potential of the soil to inhibit the growth of fungal pathogens
- Abundance and diversity of nematodes in the rhizosphere
- Abundance of coliforms in soil and on plant
- Soil quality (structure, texture, nutrient content…)


Our project seeks to evaluate the effects of organic agricultural treatments (composts and compost teas) compared to conventional agriculture (fertilizer) on (i) the production of tomatoes, (ii) the number of beneficial insects, (iii) the soil microorganisms and (iv) soil quality. The experiment is conducted at UC Berkeley facilities in Albany (Gill Tract). Undergraduate student will participate in:
- Harvesting tomatoes
- Monitoring tomato plants in the field (heights of the plants, weights of tomatoes, tomato sugar content, foliage and root biomass)
- Collecting soil samples
- Performing soil microbiological analysis in the lab (total bacterial counts, detection of E. coli…)
- Characterizing soil in the lab (water content, C/N ratio, density…)


Qualifications: We are looking for highly motivated students interested in both laboratory and field work. No qualification is needed, but any experience with laboratory chemistry or microbiology is a plus.

Weekly Hours: 6-9 hrs

Off-Campus Research Site: UC Berkeley and Gill Tract (Albany)

Closed (3) Phytoremediation of Arsenic-Contaminated Soils

Closed. This professor is continuing with Spring 2017 apprentices on this project; no new apprentices needed for Fall 2017.

The overarching goal of the proposed project is to clean up soils contaminated with arsenic in one vacant block of the old Santa Fe Right-of-Way (SFROW) in Southwest Berkeley. The SFROW corridor in South Berkeley is the last undeveloped land in Berkeley, but public use is prevented due to health risks concerning soil contamination by arsenic. In fact, while US surface soils contain on average 7.2 mg of arsenic per kg of soil, samples from this site showed arsenic at levels up to 100 mg/kg. We are proposing to use an environmentally-friendly remediation approach to remove arsenic from those soils, called phytoremediation. Phytoremediation is a novel and effective approach that uses living plants for in situ remediation of contaminated soils, with less impact for the ecosystem than conventional methods including soil excavation. In order to optimize arsenic removal from soil, we will test various additions of nutrients to the soil.

The student will participate in both field work and laboratory work (mostly field work), as well as outreach work:
1) Field:
- Collecting and sieving soil samples
- Applying soil treatments
- Watering ferns
- Harvesting ferns
- Making compost

2) Laboratory :
- Measuring soil physical and chemical characteristics (pH, structure, texture, soil nutrient content, C/N...)
- Analyzing data

3) Outreach work:
- Preparing brochures about soil pollution/remediation for a large audience


Day-to-day supervisor for this project: Sarick Matzen

Qualifications: We are looking for highly motivated students interested in both field work and laboratory work. No qualification is needed, but any experience with soil analysis is a plus.

Weekly Hours: 6-9 hrs

Off-Campus Research Site: Field work is done at our field site in SouthWest Berkeley (10 minutes biking from campus)

Related website: http://celinepallud.com/

Closed (4) Managing soil to control water quality in subalpine wetlands

Closed. This professor is continuing with Spring 2017 apprentices on this project; no new apprentices needed for Fall 2017.

Our undergraduate research project fits within a larger scale project that is investigating the effects of climate change on drinking water quality from wetlands in the Colorado Rocky Mountains. We are examining the influence of changing temperature and rainfall regimes on microbially-mediated processes that control water quality. Our laboratory investigations use both natural, wetland soils and artificial soils to determine how anaerobic microbial respiration processes control important drinking water quality parameters such as dissolved organic carbon and iron concentrations.


The student will be responsible for, while under the guidance of a graduate student, experimental setup, maintenance, sample analysis, and data entry for all laboratory assays. The student will help create artificial soil aggregates and maintain flow through reactors. They will make synthetic porewater and collect porewater samples from the flow through experiments throughout the summer. Using the Ferrozine method, they will analyze porewater samples for ferrous and ferric iron content and see how this changes over time and with treatment (temperature and flow rate). They will also analyze the porewater for ions using Liquid Ion Chromatography and Dissolved Organic Carbon using a total organic carbon analyzer. Culture Shewanella putrefaciens for experiments and determine most probable number.

Qualifications: The student must have taken one chemistry class with a laboratory component. They need to be organized, self-motivated, and work well independently once trained. They need to be able to follow procedures, while troubleshooting and clearly and frequently communicating with their graduate student supervisor. They should be interested in soils, mineralogy, biogeochemistry, or water quality. Ideally, we would be able to lay a foundation of strong laboratory skills for continued collaboration towards a senior thesis project or other future projects.

Weekly Hours: 6-9 hrs