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Pyrite formation and the measurement of sulfate reduction in salt marsh sediments
860
C. ChemicalOceanography
84:6023 Enting, I.G. and G.I. Pearman, 1983. Refinements to a one-dimensional carbon cycle model. CSIRO Div. atmos. Res. tech. Pap., 3:35pp. Refinements to the 1-D model of global carbon cycling developed at CSIRO, Australia, are presented; of primary importance is the use of techniques based on constrained inversion in calibrating carbon cycle models. Present geophysical knowledge 'is generally consistent with...observations of the carbon cycle.' (bwt) 84:6024 Howarth, R.W. and Susan Merkel, 1984. Pyrite formation and the measurement of sulfate reduction in salt marsh sediments. Limnol. Oceanogr., 29(3):598-608.
A new method was used to study the formation of pyrite plus elemental S during 35SO4 reduction experiments: the reduction with chromium(II) of pyrite and elemental S to hydrogen sulfide. It is both more specific and more sensitive than our previous method, the oxidation of pyrite and elemental S to sulfate by aqua regia, which measures the formation of refractory organic S compounds as well as pyrite and elemental S. The methods compared very well in salt marsh sediments in Georgia and Massachusetts. The chromium(II) reduction method, combined with our previous results, conclusively shows that pyrite is the major product of 35SO4 reduction measurements in these sediments. The agreement between the methods indicates that the formation of 35S-labeled, refractory organic matter is a minor process if it occurs at all. Failure to explicitly measure the formation of 35S-labeled pyrite can result in the rate of sulfate reduction being underestimated by 2- to 10-fold or more. Ecosystems Center, MBL, Woods Hole, Mass. 02543, USA. 84:6025 Jeng, Woei-Lih, 1983. Pristane and phytane in marine sediments. Acta oceanogr, taiwan., 14:1-8.
Concentrations were determined by gas-liquid chromatography. Levels of these two alkanes in coral, mariculture and offshore areas generally felt in the range of 0-1 ng/g indicative of unpolluted baseline values. High concentrations of pristane (_<417 ng/g) and phytane (_<65 ng/g) found in the commercial harbor sediments can be attributed to fossil hydrocarbon contamination. Inst. of Oceanogr., Natl. Taiwan Univ., Taipei, Taiwan. 84:6026 Jenkins, M.C. and W.M. Kemp, 1984. The coupling of nitrification and denitrification in two estuarine sediments. Limnol. Oceanogr., 29(3):609-619.
OLR(1984)31 (12)
A close coupling of the two processes was demonstrated in the Patuxent River estuary in spring: >99% of the added ~SNH4 which was oxidized to IsNO3 was subsequently reduced to ~SN-labeled N 2 during 48-h incubations. In contrast, this coupled nitrification-denitrification was decreased by two orders of magnitude in the summer. This pattern of sharply seasonal nitrification was corroborated with measurements of bacterial relative abundance. Indirect evidence suggests low redox conditions (and reduced 02 concentrations) as the possible cause of decreased summertime nitrification. Estimated springtime rates of about 77-89/~mol N m ~h-t are similar to previously reported values for denitrification supported by NO 3 diffusion from overlying water to coastal sediments. Kemp: Univ. of Maryland, Horn Point Environ. Lab., P.O. Box 775, Cambridge, Md. 21613, USA. 84:6027 Lan, Shihou, Xianfen Qiao and Jianyun Lin, 1984. Distribution and behaviour of dissolved aluminium and fluoride in the Jiniong River Estuary IChiual. Taiwan Strait, 3(1):36-43. (In Chinese, English abstract.) Third Inst. of Oceanogr., Natl. Bur. of Oceanogr., People's Republic of China. 84:6028 Li, Jing, Minxiu Zhang, Chao Xu, Chongli He, Jiayi Zhou and Wanying Qian, 1981. Marine environmental geochemistry: speciation of arsenic in surface seawater of Jiaozhou Bay. J. Shandong Coll. Oceanol., 11(3):32-38. (In Chinese, English abstract.) Dept. of Mar. Chem., Shandong Coll. of Oceanol., People's Republic of China. 84:6029 Hallberg, Rolf and Magnus LindstrOm, 1981/82. Transformation of iron in aquatic environments. Stockh. Contr. Geol., 37:67-78.
Formation of the primary iron sulfides and their transformation into pyrite are discussed. Experimental data on seasonal variations of the stability of ferric iron compounds in the uppermost sediments of the Baltic Sea are presented and explained. Some examples are given of iron minerals as indicators of past aquatic environments. Dept. of Geol., Univ. of Stockholm, Box 6801, S-11386 Stockholm, Sweden. 84:6030 Prahl, F.G., G. Eglinton, E.D.S. Corner and S.C.M. O'Hara, 1984. Copepod fecal pellets as a source of dthydrophytol in marine sediments. Science, 224(4654): 1235-1237.
Phytol is an important and abundant algal lipid. It has been suggested that dihydrophytol is formed by
C. ChemicalOceanography
84:6023 Enting, I.G. and G.I. Pearman, 1983. Refinements to a one-dimensional carbon cycle model. CSIRO Div. atmos. Res. tech. Pap., 3:35pp. Refinements to the 1-D model of global carbon cycling developed at CSIRO, Australia, are presented; of primary importance is the use of techniques based on constrained inversion in calibrating carbon cycle models. Present geophysical knowledge 'is generally consistent with...observations of the carbon cycle.' (bwt) 84:6024 Howarth, R.W. and Susan Merkel, 1984. Pyrite formation and the measurement of sulfate reduction in salt marsh sediments. Limnol. Oceanogr., 29(3):598-608.
A new method was used to study the formation of pyrite plus elemental S during 35SO4 reduction experiments: the reduction with chromium(II) of pyrite and elemental S to hydrogen sulfide. It is both more specific and more sensitive than our previous method, the oxidation of pyrite and elemental S to sulfate by aqua regia, which measures the formation of refractory organic S compounds as well as pyrite and elemental S. The methods compared very well in salt marsh sediments in Georgia and Massachusetts. The chromium(II) reduction method, combined with our previous results, conclusively shows that pyrite is the major product of 35SO4 reduction measurements in these sediments. The agreement between the methods indicates that the formation of 35S-labeled, refractory organic matter is a minor process if it occurs at all. Failure to explicitly measure the formation of 35S-labeled pyrite can result in the rate of sulfate reduction being underestimated by 2- to 10-fold or more. Ecosystems Center, MBL, Woods Hole, Mass. 02543, USA. 84:6025 Jeng, Woei-Lih, 1983. Pristane and phytane in marine sediments. Acta oceanogr, taiwan., 14:1-8.
Concentrations were determined by gas-liquid chromatography. Levels of these two alkanes in coral, mariculture and offshore areas generally felt in the range of 0-1 ng/g indicative of unpolluted baseline values. High concentrations of pristane (_<417 ng/g) and phytane (_<65 ng/g) found in the commercial harbor sediments can be attributed to fossil hydrocarbon contamination. Inst. of Oceanogr., Natl. Taiwan Univ., Taipei, Taiwan. 84:6026 Jenkins, M.C. and W.M. Kemp, 1984. The coupling of nitrification and denitrification in two estuarine sediments. Limnol. Oceanogr., 29(3):609-619.
OLR(1984)31 (12)
A close coupling of the two processes was demonstrated in the Patuxent River estuary in spring: >99% of the added ~SNH4 which was oxidized to IsNO3 was subsequently reduced to ~SN-labeled N 2 during 48-h incubations. In contrast, this coupled nitrification-denitrification was decreased by two orders of magnitude in the summer. This pattern of sharply seasonal nitrification was corroborated with measurements of bacterial relative abundance. Indirect evidence suggests low redox conditions (and reduced 02 concentrations) as the possible cause of decreased summertime nitrification. Estimated springtime rates of about 77-89/~mol N m ~h-t are similar to previously reported values for denitrification supported by NO 3 diffusion from overlying water to coastal sediments. Kemp: Univ. of Maryland, Horn Point Environ. Lab., P.O. Box 775, Cambridge, Md. 21613, USA. 84:6027 Lan, Shihou, Xianfen Qiao and Jianyun Lin, 1984. Distribution and behaviour of dissolved aluminium and fluoride in the Jiniong River Estuary IChiual. Taiwan Strait, 3(1):36-43. (In Chinese, English abstract.) Third Inst. of Oceanogr., Natl. Bur. of Oceanogr., People's Republic of China. 84:6028 Li, Jing, Minxiu Zhang, Chao Xu, Chongli He, Jiayi Zhou and Wanying Qian, 1981. Marine environmental geochemistry: speciation of arsenic in surface seawater of Jiaozhou Bay. J. Shandong Coll. Oceanol., 11(3):32-38. (In Chinese, English abstract.) Dept. of Mar. Chem., Shandong Coll. of Oceanol., People's Republic of China. 84:6029 Hallberg, Rolf and Magnus LindstrOm, 1981/82. Transformation of iron in aquatic environments. Stockh. Contr. Geol., 37:67-78.
Formation of the primary iron sulfides and their transformation into pyrite are discussed. Experimental data on seasonal variations of the stability of ferric iron compounds in the uppermost sediments of the Baltic Sea are presented and explained. Some examples are given of iron minerals as indicators of past aquatic environments. Dept. of Geol., Univ. of Stockholm, Box 6801, S-11386 Stockholm, Sweden. 84:6030 Prahl, F.G., G. Eglinton, E.D.S. Corner and S.C.M. O'Hara, 1984. Copepod fecal pellets as a source of dthydrophytol in marine sediments. Science, 224(4654): 1235-1237.
Phytol is an important and abundant algal lipid. It has been suggested that dihydrophytol is formed by