Coastal Wetlands Part I, Microscopy Imaging Intro

Microscopic examination of the soil samples from the beaches of the Southwest Florida coastal wetlands is foundational to the understanding of this part of the State. The use of microscopy aids in determining particle size, surface roughness, percentage of constituents, homogeneity of particle size and reaction to chemicals. Much of this is silica sand called quartz. This naturally occurring glass is an enormous part of our civilization. Sand is used for construction of concrete structures like streets and highways, buildings, and infrastructure such as dams, oil fracking and park benches. It is also the basis of our communications and computer systems from silicone chips, monitor screens and fiberoptic cables. It is the window through which we look and the lens we use to see the far reaches of our universe.

The featured image is an excellent example of a grain of high quality quartz sand. It is shown as seen under microscopic examination illuminated by transmitted polarized light. It is a sample of the standard to which other samples are compared.

This is an introduction to the assessment of samples that appear through microscopic examination of these natural building blocks. The samples shown here were collected from the surface of the beaches along a few miles north of Naples, Florida’s west facing coast. They were collected and recorded in the database found at Beaches of Southwest Florida

This posting is intended to assist you in interpreting the reported results of observations made.

This square meter of costal hinterland is packed with information. It is site #87 in the Costal Database. The following micrografs were made with just a pinch of the surface soil.

Through the microscope, several light sources were used that include incident flash white light, transmitted white light, transmitted polarized white light, occasional combinations of these sources, transmitted ultra blue light for fluorescence and selected color filtered light. These images will be identified by observation number as shown in the database.

#87, Fig 1. Sample showing clear quartz and transparent quartz particles with white transmitted light
#87, Fig 2. Sample showing colorful quartz and transparent quartz particles using polarized transmitted light
#87, Fig 3. Sand sample 5x polarized transmitted and flash light. Note the rounded corners of the quartz sand grains when compared to the wharf edges of the cover picture.
#87, Fig 4. same sample but added vinegar. Spherical bubbles are easily identified forming during the test process. See video below.
#87, Fig 5. This movie clip shows the off gassing of carbon dioxide from a fragment of mollusk shell as it goes into solution. Note the developmental striations in the shell sample.

These findings are reported in the database as a ‘1’ in the response choice.

Other characteristics are also recorded as shown in the following chart extracted from the database site. Where homogeneity ranges from poor to very well, size ranges from coarse to very fine, shape ranges from sharp to well rounded, source is by mineral composition, quartz ratio is in percentage by count of particles in the field of view X3, particle size can be measured down to .035 mm. Further sizing of smaller dimension is by micrometer.

Chart sample of finding characteristics of observation #87

The quartz portion of the sand is the common building block of most beaches. Under polarized light it behaves like a prism and is polychromatic. This feature is readily identifiable as a distinguishing feature. The non quartz particles may be of other ingredients such as stone, fossil, coral, plastic resin, or other salts. When vinegar is added to the sample a chemical reaction transpires where calcium carbonate reacts with the weak acid and goes into solution releasing the carbon dioxide as a gas in bubble form. This is seen in the video micrograph. The non quartz shell findings can also be distinguished by the repetitive pattern of growth and development lines in the fragments.

I hope that you find this useful when you check out our new database link Beaches of SWFL

#photomicrograph #quartz #sand #videomicrograph #polarized light #database #beaches #Southwest Florida #SWFL #transmitted light #reflected direct light #costal ecosystems

The microscope used is referenced on an earlier posting

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