Dr. James McManus

Dr. James McManus

Title: Professor and Chair
Department: Geosciences
Office: CRH 114
Phone: 330-972-7991
Fax: 330-972-7611
Email: jmcmanus@uakron.edu
Website: http://scholar.google.com/citations?user=aAv58RkAAAAJ&hl=en

Research Accomplishments

Research Interests

My research focuses on a variety topics related to Earth and ocean biogeochemistry. Research topics include studies on past ocean conditions and climate, modern biogeochemical processes, and how anthropogenic perturbations might influence biogeochemical cycles in the future. My research examines elemental cycling in the ocean, estuaries, rivers, and lakes.  I have a number of ongoing projects in marine and freshwater environments. 

Current Research

I have a number of ongoing projects that examine trace element and biogenic material cycling in marine and freshwater environments. I have a specific interest in developing trace element “tools” for interpreting the Earth's geologic record of climate and chemical variation. Some of the elements and their isotopes that I have recently been working on include germanium, molybdenum, and iron.



Deutsch, C., Berelson, W., Thunell, R., Weber, T., Tems, C., McManus, J., Crusius, J., Ito, T., Baumgartner, T., Ferreira, V., Mey, J., van Geen, A. Centennial changes in North Pacific anoxia linked to tropical trade winds, Science, 345, 665-668 http://www.sciencemag.org/content/345/6197/665.abstract

Chase, Z., McManus, J., Mix, A., *Muratli, J. Biogenic flux along the Chilean margin over the past 30,000 years, Quaternary Science Reviews, 99, 135-145. http://www.sciencedirect.com/science/article/pii/S0277379114002443

Scholz, F., Severmann, S., McManus, J., Hensen, C. (2014) Beyond the Black Sea paradigm: The sedimentary fingerprint of an open-marine iron shuttle, Geochim. Cosmochim. Acta, 127:368-380. http://www.sciencedirect.com/science/article/pii/S0016703713006807

Scholz, F., McManus, J., Mix, A.C., Hensen, C., Schneider, R.R. (2014) The impact of ocean deoxygenation on iron release from continental margin sediments, Nature Geoscience, 7: 433-437, published online: 18 May 2014, DOI: 10.1038/NGEO2162.


Chong, L.S., Berelson, W.M., McManus, J., Hammond, D.E., Rollins, N.E., Yager, P.L. (2014) Carbon and biogenic silica export influenced by the Amazon River plume: Patterns of remineralization in deep-sea sediments. Deep Sea Research, 85: 124-137.


Scholz, F., McManus, J., Sommer, S. (2013) The Manganese and iron shuttle in a modern euxinic basin and implications for molybdenum cycling at euxinic ocean margins. Chemical Geology, 355, Pages 56–68. http://www.sciencedirect.com/science/article/pii/S0009254113003094

Goldberg, T., Gordon, G., Izon, G., Archer, C., Pearce, C.R., McManus, J., Anbar, A.D., and Rehkämper, M. (2013) Resolution of inter-laboratory discrepancies in Mo isotope data: an intercalibration. J. Anal. At. Spectrom., DOI: 10.1039/C3JA30375F, http://pubs.rsc.org/en/content/articlelanding/2013/ja/c3ja30375f

Berelson, W.M., McManus, J., Severmann, S., Reimers, C.E. (2013) Benthic flux of oxygen and nutrients across Oregon/California shelf sediments. Continental Shelf Research, 55, 66-75. http://dx.doi.org/10.1016/j.csr.2013.01.009

Roy, M., McManus, J., Goñi, M.A., Chase, Z., Borgeld, J.C., Wheatcroft, R.A., Muratli, J.M., Megowan, M.R., Mix, A. (2013). Reactive iron and manganese distributions in seabed sediments near small mountainous rivers off Oregon and California, (USA). Continental Shelf Research, 54, 67-69. http://dx.doi.org/10.1016/j.csr.2012.12.012


McManus J., Berelson, W.M., Severmann, S., Johnson, K.S., Hammond, D.E., Roy, M., Coale, K.H. 2012. Benthic manganese fluxes along the Oregon-California continental shelf and slope, Continental Shelf Research, 43: 71-85.

Homoky, W., Severmann, S., McManus, J., Berelson, W.M., Riedel, T.E., Statham, P.J., Mills, R.A. (2012) Dissolved oxygen and suspended particles regulate the benthic flux of iron from continental margins. Marine Chemistry, 134-135, 59-70.

Poulson Brucker, R., McManus, J., Poulton, S.W. (2012) Molybdenum isotope fractionations observed under anoxic experimental conditions, Geochem. J., 46, 201-209.

Ziebis, W., McManus, J., Ferdelman, T., Schmidt-Schierhorn, F., Bach, W., Muratli, J., Edwards, K.J., Villinger, H. (2012) Interstitial fluid chemistry of sediments underlying the North Atlantic gyre and the influence of subsurface fluid flow. Earth Planet. Sci. Letts., 323-324, 79-91.

Muratli, J.M., McManus, J., Mix, A., Chase, Z. (2012) Dissolution of fluoride complexes following microwave-assisted hydrofluoric acid digestion of marine sediments. Talanta, 89, 195-200.

Chong, L.S., Prokopenko, M.G., Berelson, W.M., Townsend-Small, A., McManus, J. (2012) Nitrogen cycling within suboxic and anoxic sediments from the continental margin of Western North America. Marine Chemistry, 128-129, 13-25.


Poulson Brucker, R., J. McManus, S. Severmann, J. Owens, T.W. Lyons. (2011) Trace metal enrichments in Lake Tanganyika sediments: Controls on trace metal burial in lacustrine sediments. Geochem. Cosmochim. Acta. 75, 483-499. doi:10.1016/j.gca.2010.09.041

Siebert, C., D. E. Hammond, A. Ross, J. McManus. (2011) Erratum to C. Siebert, A. Ross and J. McManus (2006) “Germanium isotope measurements of high-temperature geothermal fluids using double-spike hydride generation MC-ICP-MS”, Geochimica et Cosmochimica Acta 70, 3986–3995. Geochem. Cosmochim. Acta. 75, 6267-6269. 


Severmann S., McManus J., Berelson W. M., and Hammond D. E. (2010) The continental shelf benthic iron flux and its isotope composition. Geochem. Cosmochim. Acta. 74 3984-4004, doi:10.1016/j.gca.2010.04.022. 

Muratli, J.M., Z. Chase, A.C. Mix, and J. McManus. (2010) Increased glacial-age ventilation of the Chilean margin by Antartic Intermediate Water. Nature Geoscience 3, 23 – 26, DOI: 10.1038/NGEO0715. (Published online Dec. 13, 2009) DATA Link: http://hurricane.ncdc.noaa.gov/pls/paleox/f?p=519:1:2753773130701464::::P1_STUDY_ID:10333

Muratli, J.M., Z. Chase, J. McManus and A.C. Mix. (2010) Ice-sheet control of continental erosion in central and southern Chile (36° - 41°S) over the last 30,000 years. Quaternary Science Reviews, doi:10.1016/j.quascirev.2010.06.037. DATA Link: ftp://ftp.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/muratli2010b/muratli2010b.xls


Poulson Brucker, R.L., J. McManus, S. Severmann, W. M. Berelson. (2009) Molybdenum behavior during early diagenesis: Insights from Mo isotopes. Geochemistry, Geophysics, Geosystems. Volume 10, Number 6, Q06010, doi:10.1029/2008GC002180.


Wheat, C.G. and J. McManus. (2008) Germanium in mid-ocean ridge flank hydrothermal fluids. Geochemistry, Geophysics, Geosystems. Volume 9, Number 3, Q03025, doi:10.1029/2007GC001892.

McQuay, E.L., M. E.Torres, R. W. Collier, C-A Huh, J. McManus. (2008) Contribution of cold seep barite to the barium geochemical budget of a marginal basin. Deep Sea Research I., 10.1016/j.dsr.2008.03.001

Severmann, S., T. W. Lyons, A. Anbar, J. McManus, G. Gordon. (2008) A modern iron isotope perspective on the redox evolution of ancient oceans. Geology, June 2008; v. 36; no. 6; p. 487–490; doi: 10.1130/G24670A.1; Data Repository item 2008110.

Hulme, S.M., C.G. Wheat, R.M. Coggon, and J. McManus. (2008) Data Report: Trace element, Sr isotope, and Ge/Si composition of fluids and sediments in Ridge-Flank Low-Temperature Hydrothermal Environments. ODP Scientific Results volume for Leg 301 http://publications.iodp.org/proceedings/301/301toc.htm#Expedition%20Reports


 McManus, J., W. M. Berelson, S. Severmann, R. Poulson, D. E. Hammond, C. Holm, and G. P. Klinkhammer. (2006) Molybdenum and uranium geochemistry in continental margin sediments: Paleoproxy potential. Geochim. Cosmochim. Acta. 70: 4643-4662.

 Siebert, C., A. Ross, J. McManus. (2006) Germanium isotope measurements of high-temperature geothermal fluids using double-spike hydride generation MC-ICPMS. Geochim. Cosmochim. Acta. 70: 3986-3995.

 Poulson, R.L., C. Siebert, J. McManus, and W. Berelson. (2006) Authigenic Molybdenum Isotope Signatures in Marine Sediments. Geology 34: 617-620.

 Severmann, S., C. M Johnson, B. L. Beard and J. McManus. (2006) The effect of early diagenesis on the Fe isotope compositions of porewaters and authigenic minerals in continental margin sediments. Geochim. Cosmochim. Acta. 70: 2006-2022.

 Siebert, C., J. McManus, A. Bice, R. Poulson, and W. M. Berelson. (2006) Molybdenum isotope signatures in continental margin marine sediments. Earth and Planet. Sci. Letts. 241: 723-733.


Berelson, W.M., M. Prokopenko, A. Graham, F. Sansone, J. McManus, J. Bernard. (2005) Anaerobic diagenesis of silica and carbon in continental margin sediments: Discrete zones of TCO2 production. Geochim. Cosmochim. Acta. 69: 4111 - 4129.

 Colbert, D., and J. McManus. (2005) Manganese and Barium Cycling in a Pacific Northwest Estuary: Importance of Seasonal Variability on Elemental Distributions and Delivery to the Coastal Ocean. Continental Shelf Research, 25: 1395 - 1414.

 Wheat, C.G., and J. McManus. (2005) The role of ridge-flank hydrothermal systems on the oceanic germanium and silicon balances. Geochim. Cosmochim. Acta, 69: 2021 - 2029.

 Bernhard, A.E., D. Colbert, J. McManus, and K. Field. (2005) Microbial community dynamics based on 16S rDNA profiles in a Pacific Northwest estuary and its tributaries. FEMS Microbiology Ecology. 52: 115-128.

 McManus, J. William M. Berelson, Gary P. Klinkhammer, Douglas E. Hammond, and Chris Holm. (2005) Authigenic uranium: Relationship to oxygen penetration depth and organic carbon rain. Geochim. Cosmochim. Acta. 69: 95-108.


 Johnson, T.C., E.T. Brown, and J. McManus. (2004) Diatom productivity in Northern Lake Malawi during the past 25,000 years: The intertropical convergence zone and comparisons to other high resolution paleoclimate records from East Africa. In: R.W. Battarbee, F. Gasse, and C.E. Stickley eds. Past climate variability through Europe and Africa. Kluwer Academic.

 Heinen, E.A. and J. McManus. (2004) Carbon and nutrient cycling at the sediment-water boundary in western Lake Superior. Journal of Great Lakes Res. 30 (Supplement 1): 113-132.

 Komar, P.D., J. McManus, M. Styllas. (2004) Sediment accumulation in Tillamook Bay, Oregon—Natural processes versus human impacts. Journal of Geology. 112: 455-469.

 Hammond, D.E., J. McManus, W.M. Berelson. (2004) Oceanic Germanium:Silicon Ratios: Evaluation of the potential overprint of temperature on weathering signals. Paleoceanography 19, PA2016, doi: 10.1029/2003PA000940, 2004.

 Hammond, D.E., K. M. Cummins, J. McManus, W.M. Berelson, G. Smith, F. Spagnoli. (2004) A comparison of methods for benthic flux measurement along the California margin: shipboard core incubations vs. in situ benthic landers. Limnol. Oceanogr. Methods 2: 146-159.

 Haley, B., G.P. Klinkhammer., J. McManus, (2004) Rare earth elements in pore waters of marine sediments. Geochim. Cosmochim. Acta. 68: 1265-1279.


 McManus, J., D. E. Hammond, K. Cummins, G. P. Klinkhammer, and W. M. Berelson. (2003) Diagenetic Ge-Si fractionation in continental margin environments: Further evidence for a non-opal Ge sink. Geochim. Cosmochim. Acta. 67: 4545-4557.

 Colbert, D. and J. McManus. (2003) Nutrient Biogeochemistry in an Upwelling-Influenced Estuary of the Pacific Northwest (Tillamook Bay, Oregon, USA). Estuaries. 26: 1205-1219.

 Wheat, C.G., J. McManus, M.J. Mottl, and E. Giambalvo. (2003) Oceanic phosphorus imbalance: the magnitude of the ridge-flank hydrothermal sink. Geophys. Res. Letts. 30, 17, 1895, doi:10.1029/2003GL017318, 2003.

 Baehr, M.M. and J. McManus. (2003) The measurement of phosphorus and its spatial and temporal variability in western Lake Superior. Journal of Great Lakes Res. 29(3):479-487.

 Torres, M.E., A.C. Mix, K. Kinports, B. Haley, G.P. Klinkhammer J. McManus, and M.A. de Angelis. (2003) Is methane venting at seafloor recorded by 13C benthic foraminifera shells?. Paleoceanography, 18, 3, 1062, doi1029/2002PA000842, 2003.

 McManus, J., E.A. Heinen, M. M. Baehr. (2003) Hypolimnetic oxidation rates in Lake Superior: Impact of dissolved organic material on the lake's carbon budget. Limnol. Oceanogr. 48: 1624-1632.

 Berelson, W. J. McManus, K. Coale, K. Johnson, D. Burdige, T. Kilgore, D. Colodner, F. Chavez, R. Kudela, and J. Boucher. (2003) A time series of benthic flux measurements from Monterey Bay, CA. Continental Shelf Res. 23: 457-481.


 McManus, J., T.F. Nägler, C. Siebert, C.G. Wheat, D.E. Hammond. (2002) Oceanic molybdenum isotope fractionation: Diagenesis and hydrothermal ridge-flank alteration. Geochem., Geophys., Geosys. 3(12), 1078, doi:10.1029/2002GC000356. 

 Torres, M.E., J. McManus, and C.-A. Huh. (2002) Fluid seepage along the San Clemente fault scarp: Impact on the geochemical barium cycles on a basin-wide scale. Earth and Planetary Science Letters 203: 181-194.

 Torres, M.E., J. McManus, D. Hammond, M.A. de Angelis, K. Hescheen, S. L. Colbert, M.D. Tryon, K.M. Brown, and E. Suess. (2002) Fluid and chemical fluxes in and out of sediments hosting methane hydrate deposits on Hydrate Ridge, OR. I. Hydrological provinces. Earth and Planetary Science Letters 201: 525-540.

 Johnson, T.C., E.T. Brown, J. McManus, S. Barry, P. Barker, and F. Gasse. (2002) A high-resolution record spanning the past 25,000 years in southern east Africa. Science 296: 113-132.

 McManus, J. J. Dymond, R. B. Dunbar, and R. W. Collier. (2002) Particulate barium fluxes in the Ross Sea. Marine Geology 184 (1-2): 1-15.

2001 and prior

D. Darby, J. Bischof, G. Cutter, A. de Vernal, C. Hillaire-Marcel, G. Dwyer, J. McManus, L. Osterman, L. Polyak, and R. Poore. (2001) New Record of Pronounced Changes in Arctic Ocean Circulation and Climate. Eos 82: 601, 607.

Klinkhammer, G.P., and J. McManus. (2001) Dissolved manganese and the turbidity maximum: High resolution data from the Columbia River estuary. Geochim. Cosmochim. Acta. 65: 2835-2841.

Hammond, D.E., J

McManus, C. Meredith,W M Berelson, and G P Klinkhammer. (2000) Fractionation of Ge and Si in Reducing Sediments as a Mechanism to Cause Glacial/Interglacial variations in Oceanic Ge/Si. Geochim. Cosmochim. Acta. 64: 2453-2465.

Klinkhammer, G.P., J. McManus, D. Colbert, and M.D. Rudnicki. (2000) Terrestrial dissolved organic matter at the continent-ocean boundary: Evidence for nonconservative behavior from high-resolution distributions. Geochim. Cosmochim. Acta. 64: 2765-2774.

Rushdi, A.I., J McManus, and R.W. Collier. (2000) Solubility products of barite and celestite in sea water as a function of temperature, salinity, and pressure. Marine Chemistry 69: 19-31.

Komar, P.D. and J. McManus. (2000) Natural tracers of Coastal Sediments. In: L. Ewing, O.T. Magoon and S. Robertson, eds. Sand Rights '99: Bringing back the beaches. New York, Am. Soc. Civil Eng., p. 70-84.

Tryon, M.D., K.M. Brown, M.E. Torres, J. McManus, A. Trehu, and R.W. Collier. (1999) Measurements of transience and flow cycling near episodic methane gas vents, Hydrate Ridge, Cascadia, Geology. 27: 1075-1078.

Burdige, D.J., W.M. Berelson, K.H. Coale, J. McManus, and K.S. Johnson. (1999) Fluxes of dissolved organic carbon from California continental margin sediments. Geochim. Cosmochim. Acta. 63: 1507-1515.

McManus, J., W.M. Berelson, D.E. Hammond, and G.P. Klinkhammer. (1999) Sedimentary barium cycling in the North Pacific: Implications for the utility of Ba as a paleoproductivity and a paleoalkalinity proxy. Paleoceanography. 14: 53-61.

McManus, J., W. M. Berelson, G. P. Klinkhammer, K. S. Johnson, K. H. Coale, D. C. McCorkle, D. J. Burdige, D. E. Hammond, H. Brumsack, and A. Rushdi. (1998) Geochemistry of barium in marine sediments: Implications for its use as a paleoceanographic proxy. Geochim. Cosmochim. Acta. 62: 3453-3473.

Wheat, C.G., J. McManus, J. Dymond, R.W. Collier, and M. Witicar. (1998) Hydrothermal fluid circulation through the sediment of Crater Lake, Oregon: Pore water and heat flow data. Journal of Geophys. Res. No. B5, 103: 9931-9944.

Berelson, W., R. Anderson, R. Collier, J. Dymond, D. DeMaster, D. Hammond, S. Honjo, M. Leinen, J. McManus, R. Pope, C. Smith, and M. Stephens. (1997) Biogenic Budgets of rain, regeneration, and sediment accumulation in the Equatorial Pacific. Deep Sea Res. 44: 2251-2282.

McManus, J., W.M. Berelson, T.E. Kilgore, K. Coale, and K Johnson. (1997) Phosphorus regeneration in continental margin sediments. Geochim. Cosmochim. Acta. 61:2891-2907.

Dymond, J., R.W. Collier, J. McManus, S. Honjo, and S. Manganini. (1997) Can the Al/Ti ratio in marine sediments be used as a paleoproductivity proxy? Paleoceanography 12:586-593.

Hammond, D.E., J. McManus, W.M. Berelson, T.E. Kilgore, and R. Pope. (1996) Early diagenesis of organic material in Equatorial Pacific sediments: stoichiometry and kinetics. Deep Sea Res. 43:1365-1412.

Berelson, W.M., J. McManus, T.E. Kilgore, K. Coale, K. Johnson, D. Burdige, and C. Pilskaln. (1996) Biogenic matter diagenesis on the sea floor: A comparison between two continental margin transects. Journal of Marine Research. 54:731-762.

McManus, J., R. Collier, J. Dymond, C.G. Wheat and G. Larson. (1996) Spatial and temporal distribution of dissolved oxygen in Crater Lake, Oregon. Limnology and Oceanography. 41: 722-731.

Dymond, J., R. Collier, J. McManus, and G. Larson. (1996) Unbalanced particle flux budgets in Crater Lake, Oregon: Implications for edge effects and sediment focusing in lakes. Limnology and Oceanography. 41: 732-743

McManus, J, W.M. Berelson, D.E. Hammond, T.E. Kilgore, O.G. Ragueneau, D.J. DeMaster and R.W. Collier. (1995) Early diagenesis of biogenic silica: Dissolution rates, kinetics, and paleoceanographic implications. Deep Sea Res. 42: 871-903.

McManus, J., W. M. Berelson, G. P. Klinkhammer, T. E. Kilgore, and D.E. Hammond. (1994) Barium remobilization fluxes along the continental margin. Geochim. Cosmochim. Acta., 58: 4899-4907.

Berelson, W.M., D.E. Hammond, J. McManus, and T. Kilgore. (1994) Dissolution kinetics of calcium carbonate in Equatorial Pacific sediments. Global Biogeochemical Cycles. 8: 219-235.

McManus, J., R. Collier, and J. Dymond. (1993) Mixing processes in Crater Lake, Oregon. Journal of Geophys. Res. 98: 18295-18307.

McManus, J., R. Collier, C.T. Chen, and J. Dymond. (1992) Physical properties of Crater Lake, Oregon: A method for the determination of a conductivity- and temperature-dependent expression for salinity. Limnology and Oceanography 37: 41-53.

Collier, R.W., J. Dymond, J. McManus. (1991) Studies of hydrothermal processes in Crater Lake, OR. (Report to the National Park Service). http://ir.library.oregonstate.edu/xmlui/handle/1957/14875

 Collier, R.W., J. Dymond, J. McManus, and J. Lupton. (1990) Chemical and physical properties of the water column at Crater Lake, OR. p. 69-80. In: Crater Lake: An Ecosystem Study. E. Drake, R. Collier, J. Dymond and G.L. Larson (eds). AAAS, Pacific 


1992, Ph.D., Oceanography, Oregon State University
1986 B.Sc. Chemistry, Stockton State College