carbon and sulfur isotopic data are helpful in understanding environmental conditions under which soils are formed. soils from 18 sampling sites along a climotoposequence from higher laleh zar mountains (4,351 m above sea level with xeric-mesic soil moisture-temperature regimes) to shahdad depression (250 m above sea level with arid-hyperthermic soil moisture-temperature regimes) in kerman prov...

Biology and the environment interact, one shaping the other (1). In the oceans, the chemistry of seawater and the chemistry of life are intimately linked (2). In 1958, Alfred Redfield (3) noted that the microscopic plankton of the surface ocean contain carbon, nitrogen, and phosphorous atoms in a stoichiometry of ∼105:16:1 and that as these organisms sink and decay, the deep waters of the ocean...

At the present time, soil carbon sequestration is of paramount importance to address the imminent threat of increased atmospheric carbon dioxide, which is looming large on the very survival and existence of the biome. The quantum of all carbon everywhere in the globe is same and fixed. It exists to the tune of 800 Pg in the atmosphere, 1700 Pg in terrestrial and 38000 Pg in aquatic ecosystem. E...

During phytoplankton growth a fraction of dissolved inorganic carbon (DIC) assimilated by phytoplankton is exuded in the form of dissolved organic carbon (DOC), which can be transformed into extracellular particulate organic carbon (POC). A major fraction of extracellular POC is associated with carbon of transparent exopolymer particles (TEP; carbon content = TEPC) that form from dissolved poly...

Turnover of deep organic carbon in cultivated soils: an estimate from a review of isotope data Description of the subject. This study is an estimate of medium-term renewal (decades) of deep carbon in cultivated soils. Objectives. Sequestration of organic carbon in soils is a way to mitigate the global rise in CO2 and warming. Deep horizons (> 30 cm) contain about half of the soil organic carbon...

Allochthonous organic carbon can subsidize consumers in aquatic systems, but this subsidy may only be significant in relatively small systems with high organic matter loading. We tested the importance of allochthonous carbon to consumers in a relatively large (258,000 m2) clear-water lake by adding HCO3 daily for 56 d. Dissolved inorganic carbon (DIC) was substantially enriched in 13C by the ad...

[1] Ecosystem models have not comprehensively considered how interactions among fire disturbance, soil environmental conditions, and biogeochemical processes affect ecosystem dynamics in boreal forest ecosystems. In this study, we implemented a dynamic organic soil structure in the Terrestrial Ecosystem Model (DOS‐TEM) to investigate the effects of fire on soil temperature, moisture, and ecosys...

The Toarcian oceanic anoxic event (T-OAE; ∼ 183 million y ago) is possibly the most extreme episode of widespread ocean oxygen deficiency in the Phanerozoic, coinciding with rapid atmospheric pCO2 increase and significant loss of biodiversity in marine faunas. The event is a unique past tipping point in the Earth system, where rapid and massive release of isotopically light carbon led to a majo...

[1] To study cycling of organic fractions in the ocean, relative abundances and radioand stable-carbon isotope measurements of total lipid extract, acid-soluble, and acidinsoluble fractions of suspended particulate organic carbon (POC) were made. Changes in relative abundances occurred mostly in the upper 1000 m of the water column, with a decrease in total lipid extract and the acid-soluble fr...

We conducted a source apportionment and investigated the atmospheric behavior of carbonaceous aerosols during hazy and normal days using radiocarbon ((14)C) and biomass burning/secondary organic aerosol (SOA) tracers during winter in Guangzhou, China. Haze episodes were formed either abruptly by local emissions or through the accumulation of particles transported from other areas. The average c...