Particle Size Distribution and Concentration of Total Suspended Matter in Southern Lake Michigan : January 28 - February 10, 1998

By Winkelman, Andrew G.

Excerpt
Excerpt: PARTICLE SIZE DISTRIBUTION AND CONCENTRATION OF TOTAL SUSPENDED MATTER IN SOUTHERN LAKE MICHIGAN, JANUARY 28 to FEBRUARY 10, 1998. Profiles of grain size distributions of suspended matter in the water column of southern Lake Michigan are presented from a cruise from January 28 through February 10, 1998. This cruise was prior to the very large sediment resuspension event that began on March 10, 1998. The majority of samples had less than 1 mg/L of Total Suspended Material (TSM), although concentrations were higher off Racine, WI and Saugatuck, MI. An inverse thermal stratification was observed at Racine, all other stations were well-mixed. Although the error was large, the distribution of particle sizes throughout the coastal region of the southern basin were remarkably consistent, with the peak of the mass distribution generally between 20 and 40 mm.

Table of Contents
CONTENTS PAGE Abstract........................................................................................................................................................ 5 1. Introduction ............................................................................................................................................ 5 2. Methods .................................................................................................................................................. 7 3. References .............................................................................................................................................. 8 Figures and Tables Figure 1.--Cruise track of the RV Lake Guardian. Hydrocast stations are identified on each transect ....... 6 Figure 2.--Correlation of the Sea Tech 25 cm transmissometer with filtered TSM samples. TSM = 1.58*BAC - 0,24 (r2 = 0.92 for n = 48). .......................................................................... 8 Figure 3.--The average fraction of total TSM mass versus particle size distribution for all 48 samples collected on the cruise. The size scale is in 1 mm increments from 1 to 16 mm, then 5 mm increments to 90 mm; the vertical line identifies the scale break. Only station averages were used; individual sample errors were not propagated....................... 9 Figure 4.--The average fraction of total TSM mass versus particle size distribution for the 4 offshore surface samples. ........................................................................................................................... 9 Figure 5.--The average fraction of total TSM mass versus particle size distribution for all 12 surface samples ...................................................................................................................................... 10 Figure 6.--The average fraction of total TSM mass versus particle size distribution for samples collected at 1 m above the bottom at the 12 stations ................................................................................. 10 Figure 7.--The cumulative fraction of total TSM mass versus particle size distribution for all 48 samples collected on the cruise. Only station averages were used; individual sample errors were not propagated. the horizontal dashed line represented 90% of the cumulative fraction mass. The vertical dashed line represents the particle size at which 90% of the cumulative fraction mass is less than or equal to .................................................................................................................... 10 Figure 8.--The cumulative fraction of total TSM mass versus particle size distribution for the four offshore surface samples. ................................................................................................................ 10 Figure 9.--The cumulative fraction of total TSM mass versus particle size distribution for all 12 surface samples ...................................................................................................................................... 10 Figure 10.--The cumulative fraction of total TSM mass versus particle size distribution for samples collected at 1 m above the bottom at 12 stations ....................................................................... 10