About

Arturo Keller is a Distinguished Professor at the Bren School of Environmental Science & Management at UC Santa Barbara. His research focuses on the sustainable use of chemicals and materials in modern society, emphasizing understanding and quantifying their potential impacts while seeking ways to minimize these impacts and achieve benefits. He has a particular interest in emerging materials such as nanoparticles and biochemicals, for which limited information is available. Additionally, Dr. Keller conducts large-scale work to design improved management strategies for common chemicals like fertilizers and pesticides. Dr. Keller is known for his involvement in the phasing out of the gasoline additive MTBE, where his research demonstrated its serious effects on water resources and its modest air quality benefits compared to alternatives. He facilitated the award-winning Nitrogen TMDL process for the Santa Clara River, which successfully reached consensus through science-supported decision-making and stakeholder collaboration, earning the 2003 H. David Nahai Water Quality Award. His work with Regional Water Quality Control Boards on various TMDL processes has advanced watershed-scale water quality modeling and management. He teaches courses on Sustainable Watershed Management and is recognized for his expertise in the fate and transport of pollutants, including organic liquids and pesticides. His research team has developed technologies to address water-quality problems, including innovations in oil spill skimming technology that received coverage in the New York Times.

Research topics

• Biology
• Materials science
• Environmental chemistry
• Environmental science
• Chemistry
• Nanotechnology
• Agronomy
• Computer Science
• Ecology
• Environmental resource management
• Philosophy
• Environmental planning
• Linguistics
• Water resource management
• Environmental engineering
• Composite material
• Organic chemistry
• Metallurgy

Selected publications

• Pre-Release: Water and Sediment Quality Web Application (snakekn/pilcomayo_water_sediment_quality_app)

  Open MIND · 2026-03-18

  otherOpen accessSenior author

  This application supports stakeholders in understanding environmental conditions in the Pilcomayo River Basin, mainly within Bolivia. The web application is in pre-release and currently has bugs. It will be updated by the Bren School of the Environment's River Remedy team, with expected updates continuing until June 2026. Full Changelog: https://github.com/snakekn/pilcomayo_water_sediment_quality_app/commits/v0.1

  PublisherDOI

• Biochar Reduces Nanoplastics Uptake by Lettuce and Alleviates Its Toxicity to the Plant

  Journal of Agricultural and Food Chemistry · 2026-02-13

  article

  The accumulation of micro- and nanoplastics (MPs/NPs) in croplands threatens food quality and human health. This study investigates the effectiveness of pristine biochar (BC) and iron-doped biochar (Fe-BC), produced from pine sawdust via one-step pyrolysis, in reducing NPs uptake by lettuce (Lactuca sativa L. var. adela). Fe-BC exhibited greater porosity, higher surface area, and a slightly positive surface charge compared to BC. Using Pd-doped NPs, we confirmed that NPs can penetrate roots and translocate to leaves, accumulating more in older tissues. Soil application of 3 wt % BC or Fe-BC significantly lowered leaf NPs concentrations, with Fe-BC showing a greater reduction, by approximately 60% (from 0.90 to 0.36 mg/kg). While both BC and Fe-BC demonstrated a capacity for alleviating NPs-induced metabolic disturbances and partially restoring soil enzyme activities, Fe-BC presents a more promising amendment for mitigating NPs contamination and protecting crop quality.

  PublisherDOI

• Seed priming with bare and PVP-coated boron-based nanoparticles modulated the germination and early growth of tomato

  Plant Nano Biology · 2026-03-03

  articleOpen access

  Enhancing seed germination and early development is vital for sustainable agriculture and nutrient-efficient crop production. In this context, we investigated the application of boron-based nanoparticles (B NPs), with or without polyvinylpyrrolidone (PVP) coating (B-PVP NPs), as seed priming agents to enhance germination and early growth performance in tomato ( Solanum lycopersicum ), given the essential role of B as a micronutrient. Physicochemical characterization of B-based NPs by XRD, Raman, FTIR, and DLS confirmed the presence of B₂O₃ phases I and II, with partial β-boron composition. PVP-coating increased crystallinity and exhibited smaller crystallite sizes, therefore enhancing nanoparticle dispersion and stability. Nanopriming improved germination in a coating- and dose-dependent manner; B-PVP NPs (0.1 ppm) and B NPs (10 ppm) were the optimal treatments. In addition, redox and defense metabolisms were strongly modulated, as evidenced by total antioxidant capacity (TAC) (101.08–234.04%), GSH (-46.78%), and proline levels (-86.63%), which varied depending on dose and coating. Positive correlations of B NPs with Ca and Zn, and B-PVP NPs with Fe revealed the interactions between B-based NPs and nutrient homeostasis, and B from NPs up-regulated total soluble sugars (130.86%). In contrast, negative correlations of B-PVP NPs with total soluble sugars and chlorophyll b were identified, revealing that PVP-mediated interactions can disrupt essential metabolisms. Taking all these findings into consideration, we suggest that B NPs can serve as effective B-nanofertilizers, modulating germination and early growth of tomato, while minimizing stress-related damage. Nonetheless, proper dose management is crucial to strike a balance between efficacy and unintended nutrient homeostasis and interactions with essential metabolisms. • PVP-coating altered NPs physicochemical properties and interactions with tomato. • Boron-based NPs improved seed germination performance in tomato. • Germination gains were coating- and dose-dependent: B NPs (10 ppm), B-PVP (0.1 ppm). • NPs modulated nutrient homeostasis and metabolism in tomato seeds and seedlings. • PVP-coating disrupted total soluble sugars and B NPs up-regulated them.

  PublisherDOI

• Water and Sediment Quality Web Application

  Zenodo (CERN European Organization for Nuclear Research) · 2026-03-18

  otherOpen accessSenior author

  This application supports stakeholders in understanding environmental conditions in the Pilcomayo River Basin, mainly within Bolivia. The web application has bugs and will be updated by the Bren School of the Environment's River Remedy team, with expected updates continuing until June 2026. Full Changelog: https://github.com/nadavkempinski/pilcomayo_water_sediment_quality_app/commits/v0.1

  PublisherDOI

• A decade of nanotechnology in maize (Zea mays): Benefits, risks, and future directions

  Plant Nano Biology · 2026-02-01

  articleOpen access

  Maize ( Zea mays ) is a staple crop globally, and the application of nanotechnology holds great promise in enhancing maize growth, resilience, and yield. While various studies have reported the effects of several metallic, metalloid, and non-metallic-based nanomaterials (NMs) in maize, the full extent of their benefits, risks, and influencing factors remains to be fully understood. This systematic review of the last decade adhered to the PRISMA methodology. It examined 74 cutting-edge studies on the impact of NMs used as nanofertilizers for germination, plant growth, and abiotic stress alleviation, as nanopesticides, and the risks of NMs as toxic agents. We observed that NM-effects can be limited by influencing factors such as size, chemical composition, oxidation state, shape, surface chemistry, delivery system, exposure time, and concentration. Concentration might interplay with the exposure time, which is a crucial factor influencing a hormetic behavior of NMs in maize. NMs based on Zn, Ti, Ag, Fe, Mg, Se, and HA enhance imbibition and nutrient uptake, promoting Reactive Oxygen Species (ROS) production, and stimulating metabolic activity. In growth, NMs can up-regulate genes associated with essential metabolic processes, and the mitigation of abiotic and biotic stress has also been observed. This summary provides crucial insights into the role of nanotechnology in optimizing maize production. However, it also highlights the need for further research to fully understand this role, identify research gaps, and suggest directions for future studies in this rapidly evolving field. • NMs can enhance maize germination, growth, stress resilience, and yield. • The properties of nanomaterials (NMs) influence their effects on maize. • Hormetic behavior has been observed in NMs, such as Ti, Ag, Zn, and Se-based. • Biogenic NMs have a higher concentration threshold than chemically synthesized NMs. • Non-metallic-based NMs pose fewer risks than metallic and metalloid-based NMs.

  PublisherDOI

• Machine Learning-Based Quantitative Model of Coupled Water-Energy-Chemical-Carbon Efficiency of Wastewater Treatment Plants

  ACS ES&T Water · 2026-04-16

  article

  As typical urban facilities processing several types of resources, wastewater treatment plants (WWTPs) consume chemicals and electricity to remove pollutants, generating substantial greenhouse gas (GHG) emissions. Identifying synergistic mechanisms for reducing pollution and carbon emissions from WWTPs is essential to optimizing energy and chemical use. In this study, we propose an integrated water-energy-chemical-carbon (WECC) efficiency model that reveals the synergistic pathways for pollutant removal and carbon reduction. The model identifies optimized operational parameters by assessing the WECC efficiency of resource inputs, pollutant removal, and carbon emission from WWTPs, and predicts the optimal influent and effluent quality based on a multilayer perceptron (MLP) model. The results show that carbon source chemicals in the assessed WWTP are the main limiting factors for synergies, accounting for 40% of total chemical-related emissions. However, introducing carbon source chemicals to increase the influent organic matter concentration can reduce energy and carbon intensities by up to 34.64% and 40.96%, respectively. For other factors, synergistic effects on pollution removal and carbon reduction are expected to be achieved by increasing influent COD/TN ratio, setting a reasonable safe discharge threshold, and optimizing chemical use. This machine learning-based model of the coupled WECC efficiency is expected to improve the performance of WWTPs.

  PublisherDOI

• Improving the Sustainability of Tomato Production With Biochar and Biofertilizers in Emilia‐Romagna, Italy

  Soil Use and Management · 2025-04-01 · 4 citations

  articleOpen access

  ABSTRACT Conventional agriculture is mainly dependent on chemistry and energy to promote growth and yield and on pesticides to protect crops from pests or pathogens. Biofertilizers as plant growth‐promoting microbes (PGPM) and novel soil amendments, as biochar, are considered sustainable alternatives to diminish the excessive use of chemicals in agriculture. The effects of biochar, whether used alone or in combination with biofertilizers, are still not fully understood, and its potential benefits have yet to be thoroughly investigated. Additional field studies across various agronomic conditions are needed to confirm the impact of biochar–microbial consortia before they can be widely adopted in sustainable agricultural practices. Industrial tomato is a paradigmatic example of a culture requiring resources as well as fertilisers and energy. Results from field trials performed in two different locations in Emilia‐Romagna (Italy): Parma and Ferrara (two different fields), with both conventional and organic practices, are here reported. Biochar, PGPM and arbuscular mycorrhizal fungi (AMF) were applied in field trials for two to three consecutive years. Soil characteristics, both chemical and biological, revealed that the fields had features comparable to the average European arable soils; specifically, the rhizospheric biological diversity indexes were similar in the three locations. The most interesting results were obtained in the Parma field location, where it was observed that biochar and PGPM treatment determined a reduction in the number of not ripe fruits (average 65%). When biochar was combined with newly developed PGPM in the two conventional fields, the value of commercial production and the Brix index of the harvest increased. The biofertilizers, when combined with biochar, remarkably permitted saving 20% of chemical fertilisers with a consequent saving in greenhouse gas (GHG) emissions. These results were also considered from an economic perspective, which revealed that PGPM and biochar increase the gross margins while reducing the environmental impact of the tomato cultivation.

  PublisherOA PDFDOI

• Unraveling the effects of cerium oxide nanoparticles on the metabolism of anaerobic digestion of waste activated sludge

  Environmental Science Nano · 2025-01-01 · 1 citations

  articleOpen accessSenior author

  Influence of nanoceria in anaerobic digestion of WAS.

  PublisherOA PDFDOI

• CuO@SiO ₂ Seed Priming Enhances Drought Tolerance and Phosphorus Acquisition Efficiency of Maize

  Environmental Science & Technology · 2025-10-27 · 2 citations

  article

  Sustainable agriculture requires minimizing resource inputs while maximizing the outputs. Here, we report that rationally engineered Fenton-like CuO@SiO2 nanoparticles (NPs), as a seed priming agent (20 mg/L, 24 h), concurrently enhanced drought tolerance and phosphorus (P) acquisition efficiency of maize, a climate vulnerable staple crop. Importantly, life cycle field pot trials reveal that CuO@SiO2 NPs seed priming increased the grain yield by 9.3% and 16.6%, respectively, under normal and drought conditions, compared to the hydropriming control. This enhanced drought-resilience and yield were attributed to reactive oxygen species (ROS)-intensified root system architecture (RSA) plasticity, including enhanced root hair density, deeper primary root, and prolific lateral root branching. RNA-seq revealed the activation of genes related to RSA modulation (PLA2, PG, and EXP), P/N/S uptake and assimilation (PHT, NRT, NR, NiR, and SULTR), and drought tolerance (ELIP, LEA, and DRP) in CuO@SiO2 NPs-primed seeds. Additionally, seed priming altered the seed metabolite profile, systematically elevating the content of adenosine triphosphate (24.1%), amino acids (7.6–105%), sugars (20–24%), organic acids (49–121%), phenolic acids (47–315%), and fatty acids (4.2–39%), indicating the boosted respiration and accelerated mobilization of seed stored reserves. Collectively, this simple and inexpensive ($0.62–1.15 per acre) seed priming strategy effectively enhances maize resilience to water and nutrient stress, offering a promising path toward sustainable food security.

  PublisherDOI

• Interpretable-generative machine learning approaches for predicting simultaneous removal of organic pollutants and heavy metals from water by adsorbent materials

  Journal of Cleaner Production · 2025-11-01 · 5 citations

  article
  PublisherDOI

Recent grants

• DEVELOPING AND INTEGRATING "-OMIC" TOOLS TO ELUCIDATE NANOPARTICLE TRANSPORT MECHANISM AND RESPONSES IN AGRICULTURAL CROPS

  NSF · $390k · 2019–2022

Frequent coauthors

• Yuxiong Huang

  Tsinghua–Berkeley Shenzhen Institute

  121 shared

• Adeyemi S. Adeleye

  University of California, Irvine

  70 shared

• Hongtao Wang

  Tsinghua University

  64 shared

• Hunter S. Lenihan

  University of California, Santa Barbara

  54 shared

• Omid Bozorg‐Haddad

  University of Tehran

  51 shared

• Ali Arefinia

  University of Tehran

  51 shared

• Babak Zolghadr‐Asli

  University of Queensland

  51 shared

• Arman Oliazadeh

  50 shared

Labs

• Arturo Keller's Research GroupPI

Awards & honors

• 2003 H. David Nahai Water Quality Award