Radiocarbon and Stable Carbon Isotopes in Two Soil Profiles from Northeast India

Laskar, Amzad H.; Yadava, M. G.; Ramesh, R.

doi:10.1017/s0033822200046762

Cited by 3 publications

(3 citation statements)

References 22 publications

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“…Soil organic matter reflects the type of vegetative cover present in a given soil. [21][22][23][24][25] A simplified diagram of the distribution of δ 13 C in ecosystems is shown in Figure 1. δ 13 C is also widely used for predicting the origin of diets through time and across space.…”

Section: Stable Carbon Isotopesmentioning

confidence: 99%

“…POM, particulate organic matter; DOM, dissolved organic matter. 2,7,12,13,22,24,[34][35][36][37][38] Figure 2 A simplified diagram showing trophic enrichment in carbon and nitrogen isotopic compositions from primary producers to herbivores to predators for (A) Terrestrial ecosystem and (B) Marine ecosystem. For terrestrial ecosystem, food chain starting with both C3 and C4 plants as primary producers are shown.…”

Section: Stable Carbon Isotopesmentioning

confidence: 99%

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2017

MOJES

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Stable isotope ratios at natural abundance levels are increasingly used in ecological studies. Common uses of stable isotopes in ecology include their use as biological tracers for source identifications, tracing nutrient and contaminant flows in food webs, identifying the geographic origin of migratory animals and birds, studying crosscontinental spread of infectious diseases, diet reconstruction of extinct animals, food authentication, study of photosynthesis by different types of plants, estimating CO2 emissions from different sources to the atmosphere and quantifying relative inputs in a system. Here we review some of the applications of stable isotopes in ecological and pale ecological studies. The review is restricted to the study of natural variations of the isotopes. Recently developed advanced stable isotope tools such as clumped and triple oxygen isotopes are also introduced in ecological studies. Potential of clumped isotopes to understand the thermal physiology of dinosaurs is discussed in this review.

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Section: Stable Carbon Isotopesmentioning

confidence: 99%

Section: Stable Carbon Isotopesmentioning

confidence: 99%

Untitled

2017

MOJES

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“…The amount of organic carbon (OC) in the upper 100 cm in the world's soils is estimated to be about 1550 Pg (1 Pg = 10 15 g) (Batjes 1996). Since soils are the largest reservoir for C in the terrestrial ecosystem, they play a key role within the global carbon cycle, and SOC dynamics were examined in numerous studies of increasing organic complexity over the past decades (Scharpenseel et al 1989;Trumbore et al 1989;Becker-Heidmann and Scharpenseel 1992;Wang and Amundson 1996;Six et al 2001;Baisden et al 2002;Rethemeyer et al 2005;Dreves et al 2007;Flessa et al 2008;Marschner et al 2008;Laskar et al 2012).…”

Section: Introductionmentioning

confidence: 99%

Origin of Subsoil Carbon in a Chinese Paddy Soil Chronosequence

2013

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Rice paddies are highly important agricultural soils in view of their relevance as major staple food provider in the world and their key role in the global carbon cycle, caused by special management practices. A soil chronosequence, consisting of paddy and upland soils, developed on reclaimed estuarine sediments in the Province of Zhejiang, China, was sampled to investigate the influence of duration of agricultural use (50 to 2000 yr) on soil composition. The uniform composition of the parent material provides the unique opportunity to compare the effects of different land management practices (paddy and non-paddy) on soil carbon dynamics and the origin of organic carbon (OC) in top- and subsoils, using 14C measurements by accelerator mass spectrometry (AMS). The total soil organic carbon (TOC) was split into chemically defined pools of different mobility, namely the acid- and water-soluble fulvic acids (FA), the alkali-soluble humic acids (HA), and insoluble humin fraction. The more mobile HA and FA fractions contain significantly more 14C than the corresponding TOC and humin, indicating a downward transport of OC in the subsoil. Plant roots with 14C concentrations up to 128% of the modern standard, found far below the plough pan, reveal plant roots and root exudates as other direct sources of subsoil OC in paddy soils.

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Radiocarbon constraints imply reduced carbon uptake by soils during the 21st century

Trumbore

Torn

et al. 2016

Science

180

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Subheading: Reduced carbon uptake by soils during the 21st century One Sentence Summary:Global radiocarbon observations show that Earth system models, lacking carbon stabilization mechanisms, overestimate the 21st century soil carbon sink by almost two-fold. Abstract:Soil is the largest terrestrial carbon reservoir and may influence the sign and magnitude of carbon cycle-climate feedbacks. Changes in soil carbon-the largest terrestrial carbon reservoir-may influence the sign and magnitude of climate-carbon cycle feedbacks. Many Earth system models (ESMs) estimate a significant soil carbon sink by 2100, yet the underlying carbon dynamics determining this response have not been systematically tested against observations. Using We used  14 C data from 157 globally distributed soil profiles sampled to 1 m depth, we to show that ESMs underestimated the mean age of soil carbon by more than six-fold (430±50 years vs. 3100±1800 years). Consequently, ESMs overestimated the carbon sequestration potential of soils 21 st century soil carbon sequestration by nearly two-fold (40 ± 27%). These biasesinconsistencies suggest that ESMs must better represent carbon stabilization processes and the turnover time of slow and passive reservoirs when simulating future atmospheric CO 2 dynamics.To improve simulations of future atmospheric CO 2 and carbon storage, ESMs must better represent stabilization processes and turnover times for soil carbon pools.Keywords: soil carbon, earth system models, carbon-concentration feedback, mean age, Rapid rates of carbon sequestration in ESMs contrast with findings from CO 2 and warming experiments (7, 8) as well as multiple theoretical and observational constraints indicating slow (millennial) rates of soil organic carbon accrual and turnover (9-14). Model uncertainty-as measured by inter-model spread-is high for soil carbon turnover time (τ) and exceeds the uncertainty estimated for carbon uptake through gross primary production (GPP) (15, 16).In coupled model simulations, the relative sink strength (i.e. percentage change in soil carbon) depends on the responses of net primary production (NPP) and soil carbon dynamics to increasing atmospheric CO 2 concentrations and to a lesser extent climate change (5). Elevated warms the climate, which tends to accelerate soil carbon turnover and reduce carbon storage (the carbon-climate feedback) (17,18). Although these feedbacks oppose one another, the carbonconcentration feedback is more than 4 times greater on average than the carbon-climate feedback in current ESMs at the global scale (3). Differences in the representation of elevated CO 2 versus climate effects on ecosystem processes result in substantial variation in soil carbon sequestration estimates (19) ( Table S1).Without a strong carbon-concentration feedbacks, ESMs would likely project smaller gains or larger losses of soil carbon over the 21 st century. Our aim was to constrain the magnitude of the soil carbon-concentration feedback with soil radiocarbon observations. Radiocarbon content can b...

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Radiocarbon and Stable Carbon Isotopes in Two Soil Profiles from Northeast India

Cited by 3 publications

References 22 publications

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Origin of Subsoil Carbon in a Chinese Paddy Soil Chronosequence

Radiocarbon constraints imply reduced carbon uptake by soils during the 21st century

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