In situ variability of mass-specific beam attenuation and backscattering of marine particles with respect to particle size, density, and composition

Griet Neukermans, Hubert Loisel, Xavier Meriaux, Rosa Astoreca, David McKee

Research output: Contribution to journalArticle

120 Citations (Scopus)


This study analyzes relationships between concentration of suspended particles represented by dry mass, [SPM], or area, [AC], and optical properties including particulate beam attenuation (c(p)), side scattering (b(s)), and backscattering (b(bp)), obtained from an intensive sampling program in coastal and offshore waters around Europe and French Guyana. First-order optical properties are driven by particle concentration with best predictions of [SPM] by b(bp) and b(s), and of [AC] by c(p). Second-order variability is investigated with respect to particle size, apparent density (dry weight-to-wet-volume ratio), and composition. Overall, the mass-specific particulate backscattering coefficient, b(bp)(m) (5bbp : [SPM]), is relatively well constrained, with variability of a factor of 3-4. This coefficient is well correlated with particle composition, with inorganic particles having values about three times greater (b(bp)(m) = 0.012 m2 g21) than organic particles (b(bp)(m) = 0.005 m2 g21). The mass-specific particulate attenuation coefficient, c(p)(m) (=cp : [SPM]), on the other hand, varies over one order of magnitude and is strongly driven (77% of the variability explained) by particle apparent density. In this data set particle size does not affect c(p)(m) and affects b(bp)(m) only weakly in clear (case 1) waters, despite size variations over one order of magnitude. A significant fraction (40-60%) of the variability in b m bp remains unexplained. Possible causes are the limitation of the measured size distributions to the 2-302-mu m range and effects of particle shape and internal structure that affect b(bp) more than c(p) and were not accounted for.

Original languageEnglish
Pages (from-to)124-144
Number of pages21
JournalLimnology and Oceanography
Issue number1
Publication statusPublished - Jan 2012


  • inherent optical properties
  • particulate matter concentration
  • settling velocity
  • light-scattering
  • coastal waters
  • continental shelf
  • suspended particles
  • chlorophyll concentration
  • seawater constituents

Cite this