Jonathan Williams
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View article: Seasonal isoprene emission estimates over tropical South America inferred from satellite observations of isoprene
Seasonal isoprene emission estimates over tropical South America inferred from satellite observations of isoprene Open
Isoprene, a volatile organic compound (VOC) emitted by plants, plays a significant role in atmospheric chemistry and climate. The Amazon rainforest is a globally relevant source of atmospheric isoprene. We report isoprene emissions inferre…
View article: Coordinated volatile isoprenoid production and leaf turnover protect central Amazon Forest trees against stress
Coordinated volatile isoprenoid production and leaf turnover protect central Amazon Forest trees against stress Open
Climate stress is shifting the Amazon Forest from a carbon sink to a source, highlighting the need to understand tree resilience strategies, including leaf turnover and volatile isoprenoid (VI) production. Dry-season leaf turnover in Amazo…
View article: Mirror image molecules expose state of rainforest stress
Mirror image molecules expose state of rainforest stress Open
Monoterpenes are key to plant communication and defence against biotic (e.g., herbivory) and abiotic (e.g., heat, drought) stress. Chiral monoterpenes, like alpha-pinene, exist as mirror image pairs, known as enantiomers. Enantiomers have …
View article: Forest Diversity and Environmental Factors Shape Contrasting Soil-Litter BVOC and Methane Fluxes in Three Central Amazonian Ecosystems
Forest Diversity and Environmental Factors Shape Contrasting Soil-Litter BVOC and Methane Fluxes in Three Central Amazonian Ecosystems Open
Biogenic volatile organic compounds (BVOCs) play a crucial role in biosphere-atmosphere interactions and the global carbon cycle. While vegetation is recognized as the primary source of BVOC fluxes in forest ecosystems, recent studies sugg…
View article: Mirror image molecules expose state of rainforest stress
Mirror image molecules expose state of rainforest stress Open
Monoterpenes (C10H16) serve as a vital medium for plant communication and defence against biotic (e.g., herbivory) and abiotic (e.g., heat and drought) stresses[1-6]. Some monoterpenes, such as alpha-pinene, are chiral, existing as a (-) a…
View article: Personal care products disrupt the human oxidation field
Personal care products disrupt the human oxidation field Open
People generate hydroxyl radicals (OH) in the presence of ozone via the ozonolysis of skin-emitted alkenes. In this study, we found that the application of personal care products (PCPs) including fragrances and body lotions suppresses the …
View article: Impacts of convection, chemistry, and forest clearing on biogenic volatile organic compounds over the Amazon
Impacts of convection, chemistry, and forest clearing on biogenic volatile organic compounds over the Amazon Open
The Amazon rainforest is the largest source of biogenic volatile organic compounds (BVOCs) to the atmosphere. To understand the distribution and chemistry of BVOCs, airborne and ground-based measurements of BVOCs are conducted over the Ama…
View article: Soil and Litter BVOC and GHG Fluxes in Central Amazonia: Variability Across Forest Types and Seasons 
Soil and Litter BVOC and GHG Fluxes in Central Amazonia: Variability Across Forest Types and Seasons  Open
The Amazon rainforest, characterized by its vast biodiversity and diverse vegetation formations, plays a crucial role in global biogeochemical cycles, including the emission and consumption of biogenic volatile organic compounds (BVOCs) an…
View article: Isoprene nitrates drive new particle formation in Amazon’s upper troposphere
Isoprene nitrates drive new particle formation in Amazon’s upper troposphere Open
For several decades intense new particle formation (NPF) events have been observed by aircraft measurements in the upper tropical troposphere (UTT) (Brock et al. 1995, Weigel et al. 2011, Williamson et al. 2019). These events typically occ…
View article: Seasonal dynamics of Volatile Organic Compound Fluxes from Soil in the Amazon rainforest 
Seasonal dynamics of Volatile Organic Compound Fluxes from Soil in the Amazon rainforest  Open
Volatile organic compounds (VOCs) are important to atmospheric chemistry as they readily react with ambient oxidants, such as ozone (O3) and hydroxy radicals (OH) to produce particles, thereby influencing air quality, trace gas lifetimes a…
View article: Investigating small-scale vertical concentration gradients of formaldehyde and glyoxal above the canopy at the Amazon Tall Tower Observatory (ATTO) using two MAX-DOAS instruments
Investigating small-scale vertical concentration gradients of formaldehyde and glyoxal above the canopy at the Amazon Tall Tower Observatory (ATTO) using two MAX-DOAS instruments Open
Multi-AXis Differential Optical Absorption Spectroscopy (MAX-DOAS) measurements use trace gas absorptions in spectra of scattered sun light recorded under different elevation angles to retrieve vertical profiles of trace gas concentrations…
View article: Occurrence of a “forever chemical” in the atmosphere above pristine Amazon Forest
Occurrence of a “forever chemical” in the atmosphere above pristine Amazon Forest Open
Per- and polyfluoroalkyl substances (PFAS), often referred to as "forever chemicals", are a class of man-made, extremely stable chemicals, which are widely used in industrial and commercial applications. Exposure to some PFAS is now known …
View article: Monoterpene and sesquiterpene emissions increase with forest degradation and land use change in the Amazon Arc of Deforestation
Monoterpene and sesquiterpene emissions increase with forest degradation and land use change in the Amazon Arc of Deforestation Open
Biogenic Volatile Organic Compounds (BVOCs) are primarily emitted into the atmosphere by plants. These compounds serve various functions, including cellular protection and defense at the leaf level, chemical signaling between and within pl…
View article: Low Tropospheric Ozone Over the Indo‐Pacific Warm Pool Related to Non‐Electrified Convection
Low Tropospheric Ozone Over the Indo‐Pacific Warm Pool Related to Non‐Electrified Convection Open
Lightning is the most important source of nitric oxide (NO) in the tropical upper troposphere and controls the formation of tropospheric ozone (). It is associated with deep convection and occurs mostly over continents. The Chemistry of th…
View article: Seasonal isoprene emission estimates over tropical South America inferred from satellite observations of isoprene
Seasonal isoprene emission estimates over tropical South America inferred from satellite observations of isoprene Open
Isoprene, a volatile organic compound (VOC) emitted by plants, plays a significant role in atmospheric chemistry and climate. The Amazon rainforest is a globally-relevant source of atmospheric isoprene, influencing regional and global atmo…
View article: Comprehensive Non-targeted Molecular Characterization of Organic Aerosols in the Amazon Rainforest
Comprehensive Non-targeted Molecular Characterization of Organic Aerosols in the Amazon Rainforest Open
The Amazon rainforest plays a crucial role in the global climate system, hydrological cycle, and earth's energy balance. As one of the planet's least industrialized regions, it allows investigation of organic aerosol formation and constitu…
View article: High Concentrations of Nanoparticles From Isoprene Nitrates Predicted in Convective Outflow Over the Amazon
High Concentrations of Nanoparticles From Isoprene Nitrates Predicted in Convective Outflow Over the Amazon Open
The biogenic volatile organic compounds isoprene and α‐pinene are abundant over the Amazon and can be efficiently transported to the upper troposphere by deep convective clouds (DCC). We simulate their transport and chemistry following DCC…
View article: Isoprene nitrates drive new particle formation in Amazon’s upper troposphere
Isoprene nitrates drive new particle formation in Amazon’s upper troposphere Open
New particle formation (NPF) in the tropical upper troposphere is a globally important source of atmospheric aerosols 1–4 . It is known to occur over the Amazon basin, but the nucleation mechanism and chemical precursors have yet to be ide…
View article: An integrative approach prioritizes the orphan GPR61 genomic region in tissue-specific regulation of chronotype
An integrative approach prioritizes the orphan GPR61 genomic region in tissue-specific regulation of chronotype Open
Objectives Chronotype, a manifestation of circadian rhythms, affects morning or evening preferences and ease of getting-up. This study explores the genetic basis of morning chronotype and ease of getting-up, focusing on the G protein-coupl…
View article: Frequent rainfall-induced new particle formation within the canopy in the Amazon rainforest
Frequent rainfall-induced new particle formation within the canopy in the Amazon rainforest Open
Atmospheric aerosol particles are essential for forming clouds and precipitation, thereby influencing Earth’s energy budget, water cycle and climate on regional and global scales. However, the origin of aerosol particles over the Amazon ra…
View article: Investigating carbonyl compounds above the Amazon rainforest using a proton-transfer-reaction time-of-flight mass spectrometer (PTR-ToF-MS) with NO <sup>+</sup> chemical ionization
Investigating carbonyl compounds above the Amazon rainforest using a proton-transfer-reaction time-of-flight mass spectrometer (PTR-ToF-MS) with NO <sup>+</sup> chemical ionization Open
The photochemistry of carbonyl compounds significantly influences tropospheric chemical composition by altering the local oxidative capacity; free radical abundance in the upper troposphere; and formation of ozone, peroxycarboxylic nitric …
View article: Attribution of Excess Methane Emissions Over Marine Environments of the Mediterranean and Arabian Peninsula
Attribution of Excess Methane Emissions Over Marine Environments of the Mediterranean and Arabian Peninsula Open
To accurately assess the current atmospheric methane budget and its future trends, it is essential to apportion and quantify the anthropogenic methane emissions to specific sources. This poses a significant challenge in the under‐sampled M…