Evaluation of the LISST-ST instrument for suspended particle size distribution and settling velocity measurements

The Laser In Situ Scattering Transmissometry (LISST) instruments produced by Sequoia Scientific Inc. use light scattering to measure concentration and size distributions of sediment suspensions. In this article, the capabilities of the LISST-ST instrument are studied. The instrument reports the suspended sediment concentration and the settling velocity for eight different size classes by measuring the sediment concentration at the bottom of a small settling column. The size resolution of the LISST-100 and LISST-ST instruments is studied. This study utilizes a new inversion algorithm to obtain the size distribution from the scattered light pattern. In addition, attention is directed to observed deviations in laboratory measurements that may affect the relative concentrations and the settling velocity estimations. These deviations are analyzed in terms of: sample mixing problems; deviations on the settling of a suspension from its ideal behavior; and the effect of the shape of natural particles on laser scattering compared to that of spheres. Results suggests, of these three points the difference in the light scattering by irregular particles compared to the scattering by spheres is the main source of deviation on the settling velocity estimations. Finally, practical recommendations are given in order to gain confidence in the instrument results.

[1]  J. C Winterwerp,et al.  Fine sediment dynamics in the marine environment , 2002 .

[2]  J. Hovenier,et al.  Laboratory studies of scattering matrices for randomly oriented particles , 2003 .

[3]  Paul M. Chaikin,et al.  Long-range correlations in sedimentation , 1997 .

[4]  Prabhata K. Swamee,et al.  Closure of discussion on Drag coefficient and fall velocity of nonspherical particles , 1991 .

[5]  E. Baker,et al.  The effect of particle size on the light attenuation coefficient of natural suspensions , 1984 .

[6]  H. C. Pottsmith,et al.  Laser diffraction particle sizing in STRESS , 1994 .

[7]  James D. Irish,et al.  Determining suspended sediment particle size information from acoustical and optical backscatter measurements , 1994 .

[8]  E. D. Hirleman.  Optimal Scaling of the Inverse Fraunhofer Diffraction Particle Sizing Problem: The linear system produced by quadrature , 1987 .

[9]  Y. C. Agrawal,et al.  Instruments for particle size and settling velocity observations in sediment transport , 2000 .

[10]  J. Hovenier.  Measuring Scattering Matrices of Small Particles at Optical Wavelengths , 2000 .

[12]  Hideo Yamamoto,et al.  Transformation of Diffraction Pattern due to Ellipsoids into Equivalent Diameter Distribution for Spheres , 2000 .

[13]  Xie Shizhong,et al.  Improved projection algorithm to invert forward scattered light for particle sizing. , 2001, Applied optics.

[14]  A. Jones.  Fraunhofer Diffraction by Random Irregular Particles , 1987 .

[15]  R. Chant,et al.  In situ particle size distributions and volume concentrations from a LISST-100 laser particle sizer and a digital floc camera , 2005 .

[16]  Zhenhua Ma,et al.  Characterization of large fractal aggregates by small-angle light scattering , 2002 .

[17]  Hester Volten,et al.  Scattering matrices of mineral aerosol particles at 441.6 nm and 632.8 nm , 2001 .

[18]  R. T. Cheng,et al.  Laboratory and field evaluations of the LISST-100 instrument for suspended particle size determinations , 2001 .

[19]  E. Creed,et al.  Inter-comparison of turbidity and sediment concentration measurements from an ADP, an OBS-3, and a LISST , 2001, MTS/IEEE Oceans 2001. An Ocean Odyssey. Conference Proceedings (IEEE Cat. No.01CH37295).

[20]  Stuart N. Lane,et al.  Laboratory and field assessment of an infrared turbidity probe and its response to particle size and variation in suspended sediment concentration , 1995 .

[21]  Desmond F. Lawler,et al.  Interactions of Two Settling Spheres: Settling Rates and Collision Efficiency , 1991 .

[22]  K. Cheung,et al.  Settling Characteristics of Calcareous Sand , 2003 .

[23]  R. Kuhnle,et al.  Field Techniques for Suspended-Sediment Measurement , 2000 .

[24]  E. Dan Hirleman,et al.  Laser Diffraction Spectroscopy: Influence of Particle Shape and a Shape Adaptation Technique , 1998 .

[25]  James D. Irish,et al.  A laboratory evaluation of the laser in situ scattering and transmissometery instrument using natural sediments , 1999 .

[26]  Hester Volten,et al.  Laboratory measurements of angular distributions of light scattered by phytoplankton and silt , 1998 .

[27]  Hester Volten,et al.  Experimental determination of scattering matrices of randomly oriented fly ash and clay particles at 442 and 633 nm , 2001 .

[28]  T S Huang,et al.  Iterative image restoration. , 1975, Applied optics.

[29]  S. Twomey.  Introduction to the Mathematics of Inversion in Remote Sensing and Indirect Measurements , 1997 .

[30]  M. V. Wijngaarden,et al.  In situ measurements of settling velocity and particle size distribution with the LISST-ST , 2002 .

[31]  T. Gross,et al.  In-situ measurements of particle settling velocity in the deep sea , 1991 .

[32]  M. Chahine.  Inverse Problems in Radiative Transfer: Determination of Atmospheric Parameters , 1970 .

[33]  C. Friedrichs,et al.  DETERMINING CONCENTRATION AND FALL VELOCITY OF ESTUARINE PARTICLE POPULATIONS USING ADV, OBS AND LISST , 2002 .

[34]  A. J. Bale,et al.  Intercomparison of in situ suspended matter (floc) size measurements , 1996 .

[35]  D. Thoenes,et al.  Laser Diffraction Spectrometry: Fraunhofer Diffraction Versus Mie Scattering , 1987 .

[36]  K. Dyer,et al.  A laboratory examination of floc characteristics with regard to turbulent shearing , 1999 .

[37]  J. Hovenier,et al.  Scattering matrix of quartz aerosols: comparison and synthesis of laboratory and Lorenz–Mie results , 2003 .

[38]  J B Riley,et al.  Sampling and inversion of data in diffraction particle sizing. , 1991, Applied optics.

[39]  B. Gustafson.  Microwave Analog to Light-Scattering Measurements , 2000 .

[40]  Paul S. Hill,et al.  INSSECT—an instrumented platform for investigating floc properties close to the seabed , 2004 .

[41]  G. Batchelor.  Sedimentation in a dilute dispersion of spheres , 1972, Journal of Fluid Mechanics.

[42]  H. V. Hulst.  Light Scattering by Small Particles , 1957 .

[43]  E. Hinch,et al.  Spreading fronts and fluctuations in sedimentation , 2003 .