Terrestrial ecosystem and carbon cycle feedbacks will significantly impact future climate, but their responses are highly uncertain. Models and tipping point analyses suggest the tropics and arctic/boreal zone carbon-climate feedbacks could be disproportionately large. In situ observations in those regions are sparse, resulting in high uncertainties in carbon fluxes and fluxes. Key parameters controlling ecosystem carbon responses, such as plant traits, are also sparsely observed in the tropics, with the most diverse biome on the planet treated as a single type in models. We analyzed the spatial distribution of in situ data for carbon fluxes, stocks and plant traits globally and also evaluated the potential of remote sensing to observe these quantities. New satellite data products go beyond indices of greenness and can address spatial sampling gaps for specific ecosystem properties and parameters. Because environmental conditions and access limit in situ observations in tropical and arctic/boreal environments, use of space-based techniques can reduce sampling bias and uncertainty about tipping point feedbacks to climate. To reliably detect change and develop the understanding of ecosystems needed for prediction, significantly, more data are required in critical regions. This need can best be met with a strategic combination of remote and in situ data, with satellite observations providing the dense sampling in space and time required to characterize the heterogeneity of ecosystem structure and function.

Exploring New Multi-Instrument Approaches To Observing Terrestrial Ecosystems And The Carbon Cycle From Space

Abstract The contribution of old soil C (SOM) to total soil respiration ( R S ) in forest has been a crucial topic in global change research, but remains uncertain. Isotopic methods, such as natural variations in carbon isotope composition (δ 13 C) of soil respiration, are more frequently being applied, and show promise in separating heterotrophic and autotrophic contributions to R S . However, natural and artificial modification of δ 13 C Rs can cause isotopic disequilibria in the soil-atmosphere system generating a mismatch between what is usually measured and what process-based models will predict. Here we report the partitioning of the soil surface CO 2 flux in a warm Mediterranean forest into components derived from root, litter/humus, and SOM sources using a new, three end-member mixing model, and compare this with the conventional partitioning into autotrophic and heterotrophic components. The three end-member mixing model takes into account both the discrimination during CO 2 respiration/decomposition of the three components, as well as the fractions of their CO 2 fluxes integrated over the total soil profile mass. In addition, we used a novel dual-chamber technique to ensure that δ 13 C Rs was subjected to minimal artefacts during measurement. We observed that by using measured soil surface CO 2 concentrations as a baseline level for the dual-chamber operation, it was possible to achieve and monitor the necessary conservation of the soil CO 2 steady-state diffusion conditions during the measurements, without using permanent collars inserted deeply into the soil. When R S (8.64 g CO 2  m 2  d −1 ) was partitioned into two components, the mean autotrophic and heterotrophic respiration was 56 and 44%, respectively. When R S was partitioned using the three-way model, however, roots, litter/humus, and SOM contributed 30, 33, and 37% of the total flux. Our results confirm that to improve the estimates of the partitioning method, it is important to distinguish the fractional contribution of the long-term SOM-derived flux from younger and more labile sources.

Dual-chamber measurements of δ13C of soil-respired CO2 partitioned using a field-based three end-member model

Abstract. Gas concentrations and isotopic signatures can unveil microbial
metabolisms and their responses to environmental changes in soil. Currently,
few methods measure in situ soil trace gases such as the products of
nitrogen and carbon cycling or volatile organic compounds (VOCs) that
constrain microbial biochemical processes like nitrification,
methanogenesis, respiration, and microbial communication. Versatile trace
gas sampling systems that integrate soil probes with sensitive trace gas
analyzers could fill this gap with in situ soil gas measurements that
resolve spatial (centimeters) and temporal (minutes) patterns. We developed
a system that integrates new porous and hydrophobic sintered polytetrafluoroethylene (sPTFE) diffusive
soil gas probes that non-disruptively collect soil gas samples with a
transfer system to direct gas from multiple probes to one or more central
gas analyzer(s) such as laser and mass spectrometers. Here, we demonstrate
the feasibility and versatility of this automated multiprobe system for
soil gas measurements of isotopic ratios of nitrous oxide (δ18O,
δ15N, and the 15N site preference of N2O), methane, carbon dioxide
(δ13C), and VOCs. First, we used an inert silica matrix to challenge
probe measurements under controlled gas conditions. By changing and
controlling system flow parameters, including the probe flow rate, we
optimized recovery of representative soil gas samples while reducing
sampling artifacts on subsurface concentrations. Second, we used this system
to provide a real-time window into the impact of environmental manipulation
of irrigation and soil redox conditions on in situ N2O and VOC
concentrations. Moreover, to reveal the dynamics in the stable isotope
ratios of N2O (i.e., 14N14N16O, 14N15N16O, 15N14N16O, and 14N14N18O), we
developed a new high-precision laser spectrometer with a reduced sample
volume demand. Our integrated system – a tunable infrared laser direct absorption spectrometry (TILDAS) in parallel with Vocus proton transfer reaction mass spectrometry (PTR-MS), in line with sPTFE
soil gas probes – successfully quantified isotopic signatures for N2O, CO2,
and VOCs in real time as responses to changes in the dry–wetting cycle and redox
conditions. Broadening the collection of trace gases that can be monitored in the
subsurface is critical for monitoring biogeochemical cycles, ecosystem
health, and management practices at scales relevant to the soil system.


Versatile soil gas concentration and isotope monitoring: optimization and integration of novel soil gas probes with online trace gas detection

. Gas concentrations and isotopic signatures can unveil microbial metabolisms and their responses to environmental changes in soil. Currently, few methods measure soil trace gases such as the products of nitrogen and carbon cycling, or volatile organic compounds (VOCs), that could constrain microbial biochemical processes like nitrification, methanogenesis, respiration, and microbial communication. Versatile trace gas sampling systems that integrate soil probes with sensitive trace gas analyzers could fill this gap with measurements resolving spatial (centimeter scale) and temporal (minutes) variations in concentrations and isotopic signatures of in situ soil gases. We developed a system that integrates new 15 cm long sintered PTFE diffusive soil gas probes with various infrared spectrometers and a VOC mass spectrometer. The system is based on porous and hydrophobic soil probes that non-disruptively collect and transport gas from multiple probes to one or more central gas analyzers. Here, we demonstrate the feasibility and versatility of an automated multi-probe system for soil gas measurements of isotopic ratios of nitrous oxide (δ18O, δ15N, and the 15N site-preference of N2O), methane, carbon dioxide (δ13C), and VOCs. First, we used an inert silica matrix to challenge probe measurements under controlled gas conditions. By changing and controlling system flow parameters, including probe flow rate, we optimized recovery of representative soil gas samples while reducing sampling artifacts on subsurface concentrations. Second, we forced environmental manipulations in soil-filled columns to demonstrate real-time detection of subsurface gas dynamics in response to irrigation and soil redox conditions. In addition, we developed a new laser spectrometer to recover isotope ratios for 14N14N16O ( δ446 ), 14N15N16O ( δ456 ), 15N14N16O ( δ546 ), and 14N14N18O ( δ448 ) with high precision and low concentration dependence. We captured temporal subsurface gas pulses in CO2, N2O, and VOCs. This demonstrated the potential for diffusive-based probes to couple to trace gas sensors for soil health and fertility studies, and to inform high-throughput meta-omics, leading to the development of a suite of powerful new tools for soil analysis.

/pdf/versatile-soil-gas-concentration-and-isotope-monitoring-4ynt68416j.pdf

A mid-infrared laser based analytical approach is newly developed in this study for gas chromatography (GC) separation and carbon compound specific isotope analysis (CSIA) of aromatic organic pollutants in water.

Compound specific stable carbon isotope analysis of aromatic organic contaminants in water using gas chromatography coupled to mid-infrared laser spectroscopy

Measuring techniques for concentration and stable isotopologues of CO2 in a terrestrial ecosystem: A review

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

Grega E. Voglar

Author Tools

Chat about Author

Papers

Measuring techniques for concentration and stable isotopologues of CO2 in a terrestrial ecosystem: A review