No full-text available
To read the full-text of this research,
you can request a copy directly from the author.
Specific Gravity
Abstract
The specific gravity is the observed density of a material divided by a reference value, usually water at its maximum density, i.e. 1 kg L –1 . The specific gravity varies with fluid composition and temperature, as well as the amount of dissolved and suspended matter within them. Well construction relies on the large specific gravity of drilling muds to prevent the collapse of borehole walls in unconsolidated media. The specific weight is a related measure that is the product of the fluid density and the gravitational constant. These measures are used to find the freshwater head in the water column when using pressure measurements.
ResearchGate has not been able to resolve any citations for this publication.
We present an automated, in-situ technique for measuring suspended- sediment concentrations and particle-size distributions. The technique uses pressure transducers to continuously monitor the fluid density, which is shown to be directly related to the mass of sediments suspended in the water column. We estimate the depth-integrated mass of 5 g of suspended sediments with an accuracy of 3%, corresponding to a suspended sediment concentration of 542 ± 14 mg L-1. Particle-size distributions of the sediments were estimated from the rate of change of the suspended-sediment concentrations coupled with Stokes' Law. We evaluated the accuracy using three size classes of precision glass microspheres. Good agreement between observed and calculated fall times was only found for the smallest size fraction (106 to 150 μm). Larger particles (180 to 250 μm and 300 to 425 μm) fell slower than predicted by Stokes' Law, presumably due to the onset of turbulent flow around the particles. Also, equal masses of two different sizes of microspheres did not fall independently of each other. The larger microspheres were slowed by the presence of the smaller particles while the smaller microspheres were accelerated, presumably due to entrainment of smaller particles in the wake of the larger particles. Application to laboratory characterization of soil sedimentation processes, as well as field applications for automated suspended sediment monitoring, provides the ability for real-time determination of depth-integrated sediment characteristics.