Isotopes of sulfur

Sulfur (16S) has 24 known isotopes with mass numbers ranging from 26 to 49, four of which are stable: 32S (95.02%), 33S (0.75%), 34S (4.21%), and 36S (0.02%). The preponderance of sulfur-32 is explained by its production from carbon-12 plus successive fusion capture of five helium nuclei, in the so-called alpha process of exploding type II supernovas (see silicon burning).

Other than 35S, the radioactive isotopes of sulfur are all comparatively short-lived. 35S is formed from cosmic ray spallation of 40Ar in the atmosphere. It has a half-life of 87 days. The next longest-lived radioisotope is sulfur-38, with a half-life of 17 minutes. The shortest-lived is 49S, with a half-life shorter than 200 nanoseconds.

When sulfide minerals are precipitated, isotopic equilibration among solids and liquid may cause small differences in the δS-34 values of co-genetic minerals. The differences between minerals can be used to estimate the temperature of equilibration. The δC-13 and δS-34 of coexisting carbonates and sulfides can be used to determine the pH and oxygen fugacity of the ore-bearing fluid during ore formation.

In most forest ecosystems, sulfate is derived mostly from the atmosphere; weathering of ore minerals and evaporites also contribute some sulfur. Sulfur with a distinctive isotopic composition has been used to identify pollution sources, and enriched sulfur has been added as a tracer in hydrologic studies. Differences in the natural abundances can also be used in systems where there is sufficient variation in the 34S of ecosystem components. Rocky Mountain lakes thought to be dominated by atmospheric sources of sulfate have been found to have different δS-34 values from oceans believed to be dominated by watershed sources of sulfate.

Main isotopes of sulfur (16S)
Iso­tope Decay
abun­dance half-life (t1/2) mode pro­duct
32S 94.99% stable
33S 0.75% stable
34S 4.25% stable
35S trace 87.32 d β 35Cl
36S 0.01% stable
34S abundances vary greatly (between 3.96 and 4.77 percent) in natural samples.
Standard atomic weight Ar, standard(S)
  • [32.059, 32.076][1]
  • Conventional: 32.06

List of isotopes

Z(p) N(n)  
isotopic mass (u)
half-life decay
isotope(s)[n 1]
spin and
(mole fraction)
range of natural
(mole fraction)
excitation energy
26S 16 10 26.02788(32)# 10# ms 2p 24Si 0+
27S[n 2] 16 11 27.01883(22)# 15.5(15) ms β+ (98.0%) 27P (5/2+)
β+, 2p (2.0%) 25Al
β+, p (<.1%) 26Si
28S 16 12 28.00437(17) 125(10) ms β+ (79.3%) 28P 0+
β+, p (20.7%) 27Si
29S 16 13 28.99661(5) 187(4) ms β+ (53.6%) 29P 5/2+
β+, p (46.4%) 28Si
30S 16 14 29.984903(3) 1.178(5) s β+ 30P 0+
31S 16 15 30.9795547(16) 2.572(13) s β+ 31P 1/2+
32S[n 3] 16 16 31.97207100(15) Stable 0+ 0.9493(31) 0.94454-0.95281
33S 16 17 32.97145876(15) Stable 3/2+ 0.0076(2) 0.00730-0.00793
34S 16 18 33.96786690(12) Stable 0+ 0.0429(28) 0.03976-0.04734
35S 16 19 34.96903216(11) 87.51(12) d β 35Cl 3/2+ Trace[n 4]
36S 16 20 35.96708076(20) Stable 0+ 0.0002(1) 0.00013−0.00027
37S 16 21 36.97112557(21) 5.05(2) min β 37Cl 7/2−
38S 16 22 37.971163(8) 170.3(7) min β 38Cl 0+
39S 16 23 38.97513(5) 11.5(5) s β 39Cl (3/2,5/2,7/2)−
40S 16 24 39.97545(15) 8.8(22) s β 40Cl 0+
41S 16 25 40.97958(13) 1.99(5) s β (>99.9%) 41Cl (7/2−)#
β, n (<.1%) 40Cl
42S 16 26 41.98102(13) 1.013(15) s β (96%) 42Cl 0+
β, n (4%) 41Cl
43S 16 27 42.98715(22) 260(15) ms β (60%) 43Cl 3/2−#
β, n (40%) 42Cl
43mS 319(5) keV 480(50) ns (7/2−)
44S 16 28 43.99021(42) 100(1) ms β (82%) 44Cl 0+
β, n (18%) 43Cl
45S 16 29 44.99651(187) 68(2) ms β, n (54%) 44Cl 3/2−#
β (46%) 45Cl
46S 16 30 46.00075(75)# 50(8) ms β 46Cl 0+
47S 16 31 47.00859(86)# 20# ms
[>200 ns]
β 47Cl 3/2−#
48S 16 32 48.01417(97)# 10# ms
[>200 ns]
β 48Cl 0+
49S 16 33 49.02362(102)# <200 ns n 48S 3/2−#
  1. ^ Bold for stable isotopes
  2. ^ Has 2 halo protons
  3. ^ Heaviest theoretically stable nuclide with equal numbers of protons and neutrons
  4. ^ Cosmogenic


  • The precision of the isotope abundances and atomic mass is limited through variations. The given ranges should be applicable to any normal terrestrial material.
  • Values marked # are not purely derived from experimental data, but at least partly from systematic trends. Spins with weak assignment arguments are enclosed in parentheses.
  • Uncertainties are given in concise form in parentheses after the corresponding last digits. Uncertainty values denote one standard deviation, except isotopic composition and standard atomic mass from IUPAC, which use expanded uncertainties.
  • Abundance updated from Nubase data.


  1. ^ Meija, Juris; et al. (2016). "Atomic weights of the elements 2013 (IUPAC Technical Report)". Pure and Applied Chemistry. 88 (3): 265–91. doi:10.1515/pac-2015-0305.
  2. ^ "Universal Nuclide Chart". nucleonica. (Registration required (help)). Cite uses deprecated parameter |registration= (help)

External links

Carbonate-associated sulfate

Carbonate-associated sulfates (CAS) are sulfate species found in association with carbonate minerals, either as inclusions, adsorbed phases, or in distorted sites within the carbonate mineral lattice. It is derived primarily from dissolved sulfate in the solution from which the carbonate precipitates. In the ocean, the source of this sulfate is a combination of riverine and atmospheric inputs, as well as the products of marine hydrothermal reactions and biomass remineralisation. CAS is a common component of most carbonate rocks, having concentrations in the parts per thousand within biogenic carbonates and parts per million within abiogenic carbonates. Through its abundance and sulfur isotope composition, it provides a valuable record of the global sulfur cycle across time and space.


Chlorine is a chemical element with symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between them. Chlorine is a yellow-green gas at room temperature. It is an extremely reactive element and a strong oxidising agent: among the elements, it has the highest electron affinity and the third-highest electronegativity on the Pauling scale, behind only oxygen and fluorine.

The most common compound of chlorine, sodium chloride (common salt), has been known since ancient times. Around 1630, chlorine gas was first synthesised in a chemical reaction, but not recognised as a fundamentally important substance. Carl Wilhelm Scheele wrote a description of chlorine gas in 1774, supposing it to be an oxide of a new element. In 1809, chemists suggested that the gas might be a pure element, and this was confirmed by Sir Humphry Davy in 1810, who named it from Ancient Greek: χλωρός, translit. khlôros, lit. 'pale green' based on its colour.

Because of its great reactivity, all chlorine in the Earth's crust is in the form of ionic chloride compounds, which includes table salt. It is the second-most abundant halogen (after fluorine) and twenty-first most abundant chemical element in Earth's crust. These crustal deposits are nevertheless dwarfed by the huge reserves of chloride in seawater.

Elemental chlorine is commercially produced from brine by electrolysis. The high oxidising potential of elemental chlorine led to the development of commercial bleaches and disinfectants, and a reagent for many processes in the chemical industry. Chlorine is used in the manufacture of a wide range of consumer products, about two-thirds of them organic chemicals such as polyvinyl chloride, and many intermediates for the production of plastics and other end products which do not contain the element. As a common disinfectant, elemental chlorine and chlorine-generating compounds are used more directly in swimming pools to keep them clean and sanitary. Elemental chlorine at high concentrations is extremely dangerous and poisonous for all living organisms, and was used in World War I as the first gaseous chemical warfare agent.

In the form of chloride ions, chlorine is necessary to all known species of life. Other types of chlorine compounds are rare in living organisms, and artificially produced chlorinated organics range from inert to toxic. In the upper atmosphere, chlorine-containing organic molecules such as chlorofluorocarbons have been implicated in ozone depletion. Small quantities of elemental chlorine are generated by oxidation of chloride to hypochlorite in neutrophils as part of the immune response against bacteria.

Reference materials for stable isotope analysis

Isotopic reference materials are compounds (solids, liquids, gasses) with well-defined isotopic compositions and are the ultimate sources of accuracy in mass spectrometric measurements of isotope ratios. Isotopic references are used because mass spectrometers are highly fractionating. As a result, the isotopic ratio that the instrument measures can be very different from that in the sample's measurement. Moreover, the degree of instrument fractionation changes during measurement, often on a timescale shorter than the measurement's duration, and can depend on the characteristics of the sample itself. By measuring a material of known isotopic composition, fractionation within the mass spectrometer can be removed during post-measurement data processing. Without isotope references, measurements by mass spectrometry would be much less accurate and could not be used in comparisons across different analytical facilities. Due to their critical role in measuring isotope ratios, and in part, due to historical legacy, isotopic reference materials define the scales on which isotope ratios are reported in the peer-reviewed scientific literature.

Isotope reference materials are generated, maintained, and sold by the International Atomic Energy Agency (IAEA), the National Institute of Standards and Technology (NIST), the United States Geologic Survey (USGS), the Institute for Reference Materials and Measurements (IRMM), and a variety of universities and scientific supply companies. Each of the major stable isotope systems (hydrogen, carbon, oxygen, nitrogen, and sulfur) has a wide variety of references encompassing distinct molecular structures. For example, nitrogen isotope reference materials include N-bearing molecules such ammonia (NH3), atmospheric dinitrogen (N2), and nitrate (NO3). Isotopic abundances are commonly reported using the δ notation, which is the ratio of two isotopes (R) in a sample relative to the same ratio in a reference material, often reported in per mille (‰) (equation below). Reference material span a wide range of isotopic compositions, including enrichments (positive δ) and depletions (negative δ). While the δ values of references are widely available, estimates of the absolute isotope ratios (R) in these materials are seldom reported. This article aggregates the δ and R values of common and non-traditional stable isotope reference materials.


S33 may refer to :

S33: Take precautionary measures against static discharges, a safety phrase in chemistry

33S: One of the isotopes of sulfur

S33 (Long Island bus)

S33 postcode for Hope Valley area

Blériot-SPAD S.33, a 1920 small French airliner

County Route S33, a county route in Bergen County, New Jersey

Spectrum S-33 Independence, a 2006 new Very Light Jet

USS S-33 (SS-138), a 1918 S-class submarine of the United States Navy

s.33 or Section 33 of the Canadian Charter of Rights and Freedoms, also known as the Notwithstanding Clausea shortening or designation for

Madras Municipal Airport, FAA identifier

a Zürich S-Bahn line

Shuhei Ono

Dr. Shuhei Ono is an associate professor of earth, atmospheric, and planetary sciences at the Massachusetts Institute of Technology. In his research, he measures isotopes of sulfur and other elements to investigate water-rock-microbe interactions, seafloor hydrothermal systems, the deep biosphere, and global sulfur cycles.


Sulfur or sulphur is a chemical element with symbol S and atomic number 16. It is abundant, multivalent, and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formula S8. Elemental sulfur is a bright yellow, crystalline solid at room temperature.

Sulfur is the tenth most common element by mass in the universe, and the fifth most common on Earth. Though sometimes found in pure, native form, sulfur on Earth usually occurs as sulfide and sulfate minerals. Being abundant in native form, sulfur was known in ancient times, being mentioned for its uses in ancient India, ancient Greece, China, and Egypt. In the Bible, sulfur is called brimstone, which means "burning stone". Today, almost all elemental sulfur is produced as a byproduct of removing sulfur-containing contaminants from natural gas and petroleum. The greatest commercial use of the element is the production of sulfuric acid for sulfate and phosphate fertilizers, and other chemical processes. The element sulfur is used in matches, insecticides, and fungicides. Many sulfur compounds are odoriferous, and the smells of odorized natural gas, skunk scent, grapefruit, and garlic are due to organosulfur compounds. Hydrogen sulfide gives the characteristic odor to rotting eggs and other biological processes.

Sulfur is an essential element for all life, but almost always in the form of organosulfur compounds or metal sulfides. Three amino acids (cysteine, cystine, and methionine) and two vitamins (biotin and thiamine) are organosulfur compounds. Many cofactors also contain sulfur including glutathione and thioredoxin and iron–sulfur proteins. Disulfides, S–S bonds, confer mechanical strength and insolubility of the protein keratin, found in outer skin, hair, and feathers. Sulfur is one of the core chemical elements needed for biochemical functioning and is an elemental macronutrient for all living organisms.


Troilite is a rare iron sulfide mineral with the simple formula of FeS. It is the iron rich endmember of the pyrrhotite group. Pyrrhotite has the formula Fe(1-x)S (x = 0 to 0.2) which is iron deficient. As troilite lacks the iron deficiency which gives pyrrhotite its characteristic magnetism, troilite is non-magnetic.Troilite can be found as a native mineral on Earth but is more abundant in meteorites, in particular, those originating from the Moon and Mars. It is among the minerals found in samples of the meteorite that struck Russia on February 15th, 2013. Uniform presence of troilite on the Moon and possibly on Mars has been confirmed by the Apollo, Viking and Phobos space probes. The relative intensities of isotopes of sulfur are rather constant in meteorites as compared to the Earth minerals, and therefore troilite from Canyon Diablo meteorite is chosen as the international sulfur isotope ratio standard.


The δ34S (pronounced delta 34 S) value is a standardized method for reporting measurements of the ratio of two stable isotopes of sulfur, 34S:32S, in a sample against the equivalent ratio in a known reference standard. Presently, the most commonly used standard is Vienna-Canyon Diablo Troilite (VCDT). Results are reported as variations from the standard ratio in parts per thousand, per mil or per mille, using the ‰ symbol. Heavy and light sulfur isotopes fractionate at different rates and the resulting δ34S values, recorded in marine sulfate or sedimentary sulfides, have been studied and interpreted as records of the changing sulfur cycle throughout the earth's history.

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