Pyrite formation and the measurement of sulfate reduction in salt marsh sediments

Journal Article · Tue May 01 00:00:00 EDT 1984 · Limnol. Oceanogr.; (United States)

DOI:https://doi.org/10.4319/lo.1984.29.3.0598· OSTI ID:6802846

Howarth, R W; Merkel, S

A new method was used to study the formation of pyrite plus elemental sulfur during /sup 35/SO/sub 4//sup 2 -/ reduction experiments in salt marsh sediments: the reduction with chromium(II) of pyrite and elemental sulfur to hydrogen sulfide. It is both more specific and more sensitive than the previous method, the oxidation of pyrite and elemental sulfur to sulfate by aqua regia, which measures the formation of refractory organic sulfur compounds as well as pyrite and elemental sulfur. A direct comparison of the two methods in salt marsh sediments in Georgia and in Massachusetts showed that they compare very well. The chromium(II) reduction method, combined with the authors' previous results, conclusively shows that pyrite is the major product of /sup 35/SO/sub 4//sup 2 -/ reduction measurements in these sediments. The agreement between the two methods indicates that the formation of /sup 35/S-labeled, refractory organic matter is a minor process if it occurs at all. The authors' results suggest that both the aqua regia oxidation method and the chromium(II) reduction method, if used with care, are suitable for measuring incorporation of /sup 35/S into pyrite and elemental sulfur during /sup 35/SO/sub 4//sup 2 -/ reduction measurements in salt marsh sediments. Failure to explicitly measure the formation of /sup 35/S-labeled pyrite can result in the rate of sulfate reduction being underestimated by 2-fold to 10-fold or more.

• Research Organization: Marine Biological Lab., Woods Hole, MA
• OSTI ID: 6802846
• Journal Information: Limnol. Oceanogr.; (United States), Vol. 29:3
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
SEDIMENTS
CHEMICAL ANALYSIS
SULFATES
REDUCTION
SOIL CHEMISTRY
SULFUR
WETLANDS
LABELLED COMPOUNDS
MEASURING METHODS
PYRITE
SULFUR 35
TRACER TECHNIQUES
AQUATIC ECOSYSTEMS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CHALCOGENIDES
CHEMICAL REACTIONS
CHEMISTRY
DAYS LIVING RADIOISOTOPES
ECOSYSTEMS
ELEMENTS
EVEN-ODD NUCLEI
IRON COMPOUNDS
IRON SULFIDES
ISOTOPE APPLICATIONS
ISOTOPES
LIGHT NUCLEI
MINERALS
NONMETALS
NUCLEI
OXYGEN COMPOUNDS
RADIOISOTOPES
SULFIDE MINERALS
SULFIDES
SULFUR COMPOUNDS
SULFUR ISOTOPES
TRANSITION ELEMENT COMPOUNDS
520101* - Environment
Aquatic- Basic Studies- Radiometric Techniques- (-1989)