Education

Ph.D. University of Maine

Research interests

Marine dissolved organic matter (DOM) is one of the largest reservoirs of organic carbon on the earth’s surface. Colored, or chromophoric organic matter (CDOM) is a variable component of the total DOM which interferes significantly with light propagation in surface and deep waters and greatly complicates the interpretation of remote sensing data. More importantly, the abundance and spectral characteristics of CDOM varies unpredictably over both temporal and spatial scales independently of traditional parameters (e.g. chl a, cell numbers, DOC, etc.). As a result, it is not possible to definitively correct remote sensing data for optical interferences arising from CDOM. Recent work in an adjacent oceanographic field has demonstrated that a major fraction (30-60%) of bulk marine DOM is colloidal (> 1 kDa) in nature, and preliminary evidence suggests that the optical signature of this organic colloidal matter differs markedly from the bulk CDOM. In addition, the colloidal organic fraction appears to cycle more rapidly than truly soluble organic matter. My working hypothesis is that a major part of the highly variable CDOM signal in surface waters can be explained mechanistically by short term fluctuations in the composition and cycling dynamics of colloidal CDOM. The two primary goals for this project are: 1) measure the optical signature of marine colloidal matter in nearshore waters and determine the extent to which this signature changes in response to biological activity (the source and likely sink of marine colloids), and 2) determine the extent to which photochemical processes differentially affect the optical characteristics and residence time of soluble and colloidal CDOM in seawater. The work proposed here takes the first critical steps towards physically teasing apart marine CDOM components to better explain their nature and cycling in seawater.

Publications

• Book Chapter
  Wells, M. L., 2002. Marine colloids and trace metals. In Biogeochemistry of Marine Dissolved Organic Matter. Elsevier Science, USA. Pp. 367-404
• Limnology and Oceanography
  Maldonado, M.T., M.P. Hughes, E. L. Rue, and M. L. Wells. 2002. The effect of Fe and Cu on growth and domoic acid production by Pseudo-nitzschia multiseries and Pseudo-nitzschia australis. Limnol. Oceanogr. 47:515-526.
• Marine Chemistry
  Wells, M. L., G. J. Smith, and K. W. Bruland. 2000 The distribution of colloidal and particulate bioactive metals in Narragansett Bay, RI. Mar. Chem. 71:143-163
• Limnology and Oceanography
  Wells, M. L. 1999.. Manipulating iron availability in nearshore waters. Limnology and Oceanography 44:1002-1008.
• Nature
  Wells, M. L., Vallis, G and Silver, E. 1999. Influence of tectonic processes in Papua New Guinea on past productivity in the eastern equatorial Pacific Ocean. Nature, 398:601-604.
• Marine Chemistry
  Wells, M. L.and Bruland, K. W. 1998. An improved method for rapid preconcentration and determination of bioactive trace metals in seawater using solid phase extraction and high resolution inductively coupled plasma mass spectrometry. Mar. Chem. 63:145-153.
• Marine Chemistry
  Wells, M. L., P. B. Kozelka, and K. W. Bruland. 1998. The complexation of "dissolved" Cu, Zn, Cd, and Pb by soluble and colloidal organic matter in Narragansett Bay, RI. Mar. Chem., 62:203-217.
• Nature
  Wells, M. L. 1998. Marine colloids: a neglected dimension. News and Views, Nature 391:530-531.
• Marine Chemistry
  Buesseler, K. O. et al.. 1996. An intercomparison of cross-flow filtration techniques used for sampling marine colloids: overview and organic carbon results. Mar. Chem., 55:1-31.
• Marine Chemistry Special Issue
  Marine Chemistry Special Issue. 1995. The Chemistry of Iron in Seawater and its Interaction with Phytoplankton. Co-Guest Editors K.W. Bruland and M. L. Wells. Volume 50: 1-241
• Limnology and Oceanography
  Wells, M. L., Price, N. M., and Bruland, K. W. 1994. Iron limitation and the Cyanobacterium Synechococcus in equatorial Pacific waters. Limnol. Oceanogr., 39:1481-1486.
• Nature
  Wells, M. L., 1994. Pumping Iron in the Pacific. News and Views, Nature 368:295-296.
• Limnology and Oceanography
  Wells, M. L. and Goldberg, E. D. 1994. The distribution of colloids in the North Atlantic and Southern Oceans. Limnol. Oceanogr. 39:286-302.
• Marine Chemistry
  Wells, M. L. and Goldberg, E. D. 1993. Colloid aggregation in seawater. Mar. Chem., 41:353-358.
• Marine Chemistry
  Wells, M. L. and Goldberg, E. D., 1992. Marine sub-micron particles. Mar. Chem., 40:5-18.
• Marine Ecology Progress Series
  Kepkay. P. and Wells, M. L.. 1992 Dissolved organic carbon north Atlantic surface waters. Mar. Ecol. Prog. Ser., 80:275-283.
• Deep-Sea Research
  Longhurst, A. R., Koike, L., Li, W., Rodriguez, J., Dickie, P., Kepkay, P., Partensky, F., Bautista, B., Ruiz, J., Wells, M. L. and Bird, D., 1992. Sub-micron particles in north-west Atlantic shelf water. Deep-Sea Res., Rapid Response Paper, 39:1-7.
• Nature
  Wells, M. L. and Goldberg, E. D., 1991. Small colloids in seawater. Nature 353:342-344.
• Nature
  Wells, M. L., Mayer, L. M., Donard, O. F. X., de Souza Sierra, M. M. and Ackleson, S. G., 1991. The photolysis of colloidal iron and its significance in the ocean. Nature 353:248-250.
• Deep-Sea Research
  Wells, M. L. and Mayer, L. M., 1991. The photoconversion of colloidal iron oxyhydroxides in seawater. Deep-Sea Res., Rapid Response Paper, 38:1379-1395.
• Marine Chemistry
  Wells, M. L., Mayer, L. M. and Guillard, R. R. L., 1991. A chemical method for estimating the availability of iron to phytoplankton in seawater, 1991. Mar. Chem., 33:23-40.
• Marine Ecology Progress Series
  Wells, M. L., Mayer, L. M and Guillard, R. R. L., 1991. Evaluation of Fe as a triggering factor for red tide blooms. Mar. Ecol. Prog. Ser., 69:93-102.
• Biological Oceanography
  Wells, M. L., 1991. The availability of iron in seawater: A perspective. Biol. Oceanogr., 6:463-476.
• Marine Chemistry
  Wells, M. L. and Mayer, L. M., 1991. Variations in the chemical lability of Fe in estuarine, coastal and shelf waters and its implications for phytoplankton. Mar. Chem., 32:195-210.
• Journal of Marine Research
  Wells, M. L., Zorkin, N. G. and Lewis, A. G., 1983. The role of colloid chemistry in providing a source of iron to phytoplankton. J. Mar. Res., 41:731-746.
• Marine Chemistry
  Wells, M. L., G. J. Smith, and K. W. Bruland. The distribution of colloidal and particulate bioactive metals in Narragansett Bay, RI. Mar. Chem. (in review)

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