Preprints
Filtering by Subject: Environmental Chemistry
Prioritizing Safety, Advancing Efficiency: Developing a New Total Phosphorous Microwave Digestion Method for Sediment Core Nutrient Analysis
Published: 2024-09-26
Subjects: Biogeochemistry, Environmental Chemistry, Inorganic Chemistry, Soil Science
Long-term datasets are invaluable resources for understanding broad-level temporal patterns in ecosystems. For over two decades, UC Davis and Lake County Water Resources Department have collaborated on a long-term monitoring project of Clear Lake sediment nutrient concentrations, in an effort to better understand nutrient cycling in Clear Lake. When the need for a new total phosphorus digestion [...]
Graph Characterization of Higher Order Structure in Atmospheric Chemical Reaction Mechanisms
Published: 2024-02-13
Subjects: Atmospheric Sciences, Biogeochemistry, Environmental Chemistry, Other Applied Mathematics, Other Environmental Sciences
Atmospheric chemical reactions play an important role in air quality and climate change. While the structure and dynamics of individual chemical reactions are fairly well understood, the emergent properties of the entire atmospheric chemical system, which can involve many different species that participate in many different reactions, are not well described. In this work, we leverage [...]
Soil geochemistry of hydrogen and other gases along the San Andreas Fault
Published: 2023-07-23
Subjects: Environmental Chemistry, Geochemistry, Geology, Multivariate Analysis, Oil, Gas, and Energy, Soil Science
Natural hydrogen has generated great interest as a potential clean and renewable energy source. To understand the occurrence of natural hydrogen, 103 1-m deep soil gas samples were acquired near the San Andreas Fault at Jasper Ridge and Portola Valley, California, USA. The gas samples were analyzed for hydrogen, helium, carbon dioxide, light hydrocarbons, and fixed gas concentrations. Statistical [...]
FIELD LEVEL VARIATION INFLUENCED OUTCOMES MORE THAN N-FERTILISER, FYM, COVER CROPS OR THEIR LEGACY EFFECTS FOLLOWING CONVERSION TO A NO-TILL ARABLE SYSTEM
Published: 2022-10-08
Subjects: Agriculture, Biogeochemistry, Earth Sciences, Environmental Chemistry, Other Earth Sciences, Other Environmental Sciences, Soil Science
Crop establishment in no-till arable systems benefits from favourable soil conditions. Combined with the incorporation of crop residues and manures, no-till can influence soil organic carbon (SOC) and organic matter (SOM) dynamics, crop productivity and nutrient cycling. These processes are shaped by spatial and temporal factors and associated microbial processes. There is a lack of diachronic [...]
Emerging advanced oxidation processes for water and wastewater treatment – guidance for systematic future research
Published: 2022-09-09
Subjects: Environmental Chemistry, Environmental Engineering, Environmental Sciences
Advanced oxidation processes (AOPs) for water treatment are a growing research field with a large variety of different concepts and materials being tested at laboratory scale. However, only few concepts have been translated into pilot- and full-scale operation recently. One major concern are the inconsistent experimental approaches applied across different studies that impede identification, [...]
Generation of Reproducible Model Freshwater Particulate Matter Analogues to Study the Interaction with Particulate Contaminants.
Published: 2022-08-31
Subjects: Environmental Chemistry, Environmental Health and Protection, Environmental Sciences, Fresh Water Studies
Aquatic fate models and risk assessment require experimental information on the potential of contaminants to interact with riverine suspended particulate matter (SPM). While for dissolved contaminants partition or sorption coefficients are used, the underlying assumption of chemical equilibrium is invalid for particulate contaminants, such as engineered nanomaterials, incidental nanoparticles, [...]
Unraveling the role of polysaccharide-goethite associations on glyphosate’ adsorption-desorption dynamics and binding mechanisms
Published: 2022-07-23
Subjects: Agriculture, Analytical Chemistry, Biogeochemistry, Environmental Chemistry, Environmental Sciences, Organic Chemistry, Physical Chemistry, Soil Science
Hypothesis Glyphosate retention at environmental interfaces is strongly governed by adsorption and desorption processes. In particular, glyphosate can react with organo-mineral associations (OMAs) in soils, sediments, and aquatic environments. We hypothesize mineral-adsorbed biomacromolecules modulate the extent and rate of glyphosate adsorption and desorption where electrostatic and noncovalent [...]
Advecting Superspecies: Efficiently Modeling Transport of Organic Aerosol with a Mass-Conserving Dimensionality Reduction Method
Published: 2022-06-26
Subjects: Atmospheric Sciences, Climate, Earth Sciences, Engineering, Environmental Chemistry, Environmental Engineering, Environmental Sciences, Other Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics
The chemical transport model LOTOS-EUROS uses a volatility basis set (VBS) approach to represent the formation of secondary organic aerosol (SOA) in the atmosphere. Inclusion of the VBS approximately doubles the dimensionality of LOTOS-EUROS and slows computation of the advection operator by a factor of two. This complexity limits SOA representation in operational forecasts. We develop a [...]
Freshwater Suspended Particulate Matter – Key Components and Processes in Floc Formation and Dynamics.
Published: 2022-02-18
Subjects: Biogeochemistry, Environmental Chemistry, Environmental Microbiology and Microbial Ecology Life Sciences, Environmental Sciences, Fresh Water Studies, Geochemistry, Hydrology, Sedimentology
Freshwater suspended particulate matter (SPM) plays an important role in many biogeochemical cycles and serves multiple ecosystem functions. Most SPM is present as complex floc-like aggregate structures composed of various minerals and organic matter from the molecular to the organism level. Flocs provide habitat for microbes and feed for larger organisms. They constitute microbial bioreactors, [...]
Multi-proxy assessment of surface sediments using APPI-P FTICR-MS reveals a complex biogeochemical record along a salinity gradient in the Pearl River estuary and coastal South China Sea
Published: 2021-12-10
Subjects: Analytical Chemistry, Biogeochemistry, Chemistry, Earth Sciences, Environmental Chemistry, Environmental Monitoring, Environmental Sciences, Geochemistry, Physical Sciences and Mathematics
The Pearl River drains the second largest watershed in China, funnelling large amounts of freshwater and organic matter into the northern part of the South China Sea through an estuary characterized by pronounced biogeochemical gradients. In this study we analyzed organic extracts of surface sediments collected along land-sea transect that captures a transition from freshwater environment at the [...]
BENTHIC NUTRIENT FLUXES ACROSS A PRODUCTIVE SHELF ADJACENT TO AN OLIGOTROPHIC BASIN: CASE OF THE NORTHEASTERN MEDITERRANEAN SEA
Published: 2021-04-08
Subjects: Environmental Chemistry, Oceanography
The coastal ecosystem of the Northeastern (NE) Mediterranean has been affected by nutrient inputs originated from regional rivers and wastewater discharges leading to development of eutrophication. Atmospheric nutrient inputs have also remarkable contribution to marine nutrient pool in the NE Mediterranean, especially in dry periods. Sediment porewater nutrient fluxes into the deep waters are [...]
Crisis at the Salton Sea: The Vital Role of Science
Published: 2021-03-04
Subjects: Atmospheric Sciences, Biogeochemistry, Chemistry, Climate, Earth Sciences, Environmental Chemistry, Environmental Public Health, Environmental Sciences, Environmental Studies, Geochemistry, Geology, Geomorphology, Hydrology, Medicine and Health Sciences, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics, Public Health, Social and Behavioral Sciences
The Salton Sea—a hypersaline, terminal lake in southern California—is in crisis. A combination of mismanagement and competition among federal, state and local agencies has hindered efforts to address declining lake levels and unstable water chemistry. This delay has heightened the public health threat to regional communities as retreating shorelines expose dry lakebed— a source of potentially [...]
Sedimentary structures discriminations with hyperspectral imaging on sediment cores
Published: 2020-07-17
Subjects: Analytical Chemistry, Chemistry, Earth Sciences, Environmental Chemistry, Environmental Monitoring, Environmental Sciences, Multivariate Analysis, Optics, Physical Sciences and Mathematics, Physics, Sedimentology, Statistical Models, Statistics and Probability
Hyperspectral imaging (HSI) is a non-destructive high-resolution sensor, which is currently under significant development to analyze geological areas with remote devices or natural samples in a laboratory. In both cases, the hyperspectral image provides several sedimentary structures that need to be separated to temporally and spatially describe the sample. Sediment sequences are composed of [...]
Forecasting the localized bilateral effects of ocean acidification on the counter carbonate pump using recurrent neural networks
Published: 2020-07-08
Subjects: Artificial Intelligence and Robotics, Chemistry, Computer Sciences, Environmental Chemistry, Numerical Analysis and Scientific Computing, Oceanography, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics
The counter carbonate pump(CCP) is responsible for carbon dioxide sequestration and cycling forms of carbon in the ocean. It is primarily driven by calcifying plankton, such as foraminifera, coccolithophores, and pteropods. These organisms are particularly vulnerable to ocean acidification, which can have disastrous effects on their skeletons and productivity, upsetting the marine carbon cycle in [...]
Toward stable, general machine-learned models of the atmospheric chemical system
Published: 2020-03-23
Subjects: Artificial Intelligence and Robotics, Chemistry, Computer Sciences, Earth Sciences, Environmental Chemistry, Environmental Sciences, Physical Sciences and Mathematics
Atmospheric chemistry models—used as components in models that simulate air pollution and climate change—are computationally expensive. Previous studies have shown that machine-learned atmospheric chemical solvers can be orders of magnitude faster than traditional integration methods but tend to suffer from numerical instability. Here, we present a modeling framework that reduces error [...]