A5015517890- Soil Carbon and Nitrogen Dynamics
- Groundwater and Isotope Geochemistry
- Soil and Water Nutrient Dynamics
- Isotope Analysis in Ecology
- Peatlands and Wetlands Ecology
- Climate change and permafrost
- Atmospheric chemistry and aerosols
- Atmospheric and Environmental Gas Dynamics
- Cryospheric studies and observations
- Agriculture Sustainability and Environmental Impact
- Geology and Paleoclimatology Research
- Air Quality Monitoring and Forecasting
- Climate Change Policy and Economics
- Water Quality and Pollution Assessment
- Environmental Chemistry and Analysis
- Recycling and Waste Management Techniques
- Landfill Environmental Impact Studies
- Municipal Solid Waste Management
- Catalysis and Oxidation Reactions
- Plant Diversity and Evolution
- Water-Energy-Food Nexus Studies
- Soil Geostatistics and Mapping
- Air Quality and Health Impacts
- Catalytic Processes in Materials Science
- Scientific Research and Discoveries
Instituto Venezolano de Investigaciones Científicas
2011-2023
University of California, Berkeley
2021-2023
University of California, Irvine
2005-2011
Rice University
2011
California Institute of Technology
2001
University of Wollongong
2001
Centro Internacional de Mejoramiento de Maíz Y Trigo
2001
Stanford University
2001
Irvine University
2000
University of New Hampshire
2000
Food waste is a dominant organic constituent of landfills, and large global source greenhouse gases. Composting food presents potential opportunity for emissions reduction, but data on whole pile, commercial-scale the associated biogeochemical drivers are lacking. We used non-invasive micrometeorological mass balance approach optimized three-dimensional windrow compost piles to measure methane (CH4), nitrous oxide (N2O), carbon dioxide (CO2) continuously during composting. Greenhouse gas...
Agricultural soils are the most important anthropogenic source of nitrous oxide to atmosphere. We observed large shifts with time in emission rate (from 170 16 ng N cm −2 h −1 ) and δ 15 2 O emitted −46‰ +5‰ relative atmospheric from a urea‐fertilized irrigated agricultural field Mexico. calculated overall instantaneous enrichment factors for sampling period, which suggest that microbial production nitrification (week 1) denitrification 2). Isotopic signatures emissions were not always...
We report measurements of the 15 N and 18 O signature 2 emitted from tropical rain forest soils at La Selva Biological station in Costa Rica Fazenda Vitoria State Pará, Brazil. The δ values ranged −34 to 2‰ with respect atmospheric , while had a smaller range, −4 18‰ . attribute these large variations differences microbial production, consumption, transport O. In general emissions an Oxisol soil Brazil were consistently enriched by ∼20‰ compared those Ultisol Inceptisol Rica. Denitrification...
The isotopic signatures of 15N and 18O in N2O emitted from tropical soils vary both spatially temporally, leading to large uncertainty the overall source signature thereby limiting utility isotopes constraining global budget. Determining reasons for spatial temporal variations isotope requires that we know enrichment factors nitrification denitrification, two processes produce soils. We have devised a method measuring these using soil incubation experiments report results this three rain...
[1] Nitrous oxide (N2O) is an important greenhouse gas in which the main sources are tropical rainforest and agricultural soils. N2O produced soils by microbial processes, enhanced application of nitrogenous fertilizers. The soil bulk isotopic composition (δ15Nbulk δ18O) "site-specific," or intramolecular, 15N composition, i.e., 15N/14N ratio at cenral (α) terminal (β) nitrogen position, expressed this study as δ15Nα δ15Nβ could help identify both (natural anthropogenic) pathways production...
Human impacts on the N cycle require sustainable ecological solutions to preserve ecosystem and human health.
Abstract Recent field studies have shown that there are habitats in the subarctic tundra emitting N 2 O at exceptionally high rates. In this study, stable isotope techniques were applied to characterize processes responsible for these emissions which been found from bare peat surfaces permafrost peatlands. The results include first data on nitrogen and oxygen isotopic composition of emitted arctic tundra. emission‐weighted average δ 15 bulk value −13.0‰ ± 2.0‰ (mean SD; n = 8) falls within...
Urbanization and land use changes alter the nitrogen (N) cycle, with critical consequences for continental freshwater resources, coastal zones, human health. Sewage poor watershed management lead to impoverishment of inland water resources degradation zones. Here we review N contents rivers three most important watersheds in South America: Amazon, La Plata, Orinoco basins. To evaluate potential impacts on also present data small- medium-sized Venezuelan that drain into Caribbean Sea are...
Abstract. Nitrous oxide (N2O) emissions from permafrost-affected terrestrial ecosystems have received little attention, largely because they been thought to be negligible. Recent studies, however, shown that there are habitats in the subarctic tundra emitting N2O at high rates, such as bare peat (BP) surfaces on permafrost peatlands. Nevertheless, processes behind production these high-emission poorly understood. In this study, we established an situ 15N-labeling experiment with two main...
Abstract N fertilization significantly increases 2 O and NO soil fluxes to the atmosphere. In spite of expansion agricultural activities in tropical managed soils from developing world, there is little information about loss applied nitrogen (LAN) as these areas. this work, we determined LAN‐N LAN‐NO different crops during growing season at a sandy experimental field two active farms with loamy clay soils, respectively. Tillage (T) no‐tillage (NT) farming were separately evaluated. All...
Soil nitrous oxide (N 2 O) emissions are an important driver of climate change and a major mechanism labile nitrogen (N) loss from terrestrial ecosystems. Evidence increasingly suggests that locations on the landscape experience biogeochemical fluxes disproportionate to surrounding matrix (hot spots) time periods show disproportionately high relative background moments) strongly influence landscape-scale soil N O emissions. However, substantial uncertainties remain regarding how measure...
A palynological analysis of an organic paleosol found at 150-125 cm depth in a Mauritia swamp from the Eastern Orinoco Llanos is presented. The 25 pollen record summarizes vegetation history during Early Holocene, 10,225 to 7,800 calendar yr BP. was characterized by Poaceae marsh, where Asteraceae, Melastomataceae, Schefflera-type and Phyllanthus were most abundant shrubs trees. Pollen-types richness lower than that recorded today similar environments, absent. Results suggest climate as...
Atmospheric aerosols play an important role in atmospheric processes and human health. Characterizing identifying their sources large cities is relevant to propose site-specific air pollution mitigation strategies. In this study, we measured the mass concentration of with aerodynamic diameter smaller than 2.5 µm (PM2.5) city Caracas (urban) a tropical montane cloud forest (suburban site, located mountainous area 11 km far from Caracas) between June 2018 October 2019. We also equivalent black...
In this work, we study the interaction between OH radicals with black carbon (BC) modeled by a coronene molecule means of quantum chemistry calculations MOPAC, DeMon-nano, DeMon2K packages purpose understand aging process m
Abstract. Nitrous oxide (N2O) emissions from permafrost-affected terrestrial ecosystems have received little attention, largely because they been thought to be negligible. Recent studies, however, shown that there are habitats in subarctic tundra emitting N2O at high rates, such as bare peat surfaces on permafrost peatlands. The processes behind production these high-emitting are, poorly understood. In this study, we established an situ 15N-labelling experiment with the main objectives...