radioactivity of 4 curies; the tagging efficiency was not reported. The 

 survey was essentially a zigzag pattern in the ship channel, and covered 

 a track about 1,000 feet wide and 8 miles long. The detector vehicle 

 was a sled that carried one scintillation counter with a sensitivity of 

 6,000 counts per minute per microcurie per square foot. Radioactivity 

 was recorded on an analog strip chart; counts were accumulated over a 

 10-second period. Location of the towing vehicle was determined by the 

 cutoff angle technique at 2-minute intervals. The experiment lasted 1 week; 

 one survey was made each day. Method of data reduction is not stated, but 

 it is assumed to be essentially by manual computation. Results - only 

 qualitative - are shown as a diagram indicating the presence and level of 

 radioactivity versus distance along the channel. Other WES programs of 

 this type have been conducted in San Francisco Bay, The Galveston area 

 and in Charleston, South Carolina. 



(b) Fluorescent Systems . In the United States more studies 

 using fluorescent dyes have been reported than those using radioisotopes. 

 Although most studies are at beaches, some have been made of river 

 transport . 



The United States Geological Survey (USGS) recently prepared an 

 open-file report on sediment discharge at Clear Creek, Colorado (Kennedy 

 and Kouba, 1968). In this investigation, dyed sand was introduced at a 

 constant rate at a point for a period of 28 hours. Samples were obtained 

 from a point near the stream bed 1/2 mile downstream. In this USGS study, 

 three fractions of different sizes of the sand carried by the river were 

 dyed with different colored fluorescent material. During the experiment, 

 0.2 pound (90 grams) of each size fraction were injected every 3 minutes 

 for 28 hours. About 300 pounds of sand were used. The stream was sam- 

 pled continuously during the test. Samples were dried and sieved. Each 

 size fraction was placed in a vibrating- feeder device with a spiral 

 trough, and observed under ultra-violet light so that the number of 

 fluorescent grains could be recorded with a manual counting device. 

 Results of the program are quantitative, based on the Crickmore and 

 Lean constant-injection technique. 



At the University of Florida, the Department of Coastal and Oceano- 

 graphic Engineering has been experimenting with fluorescent tracing in 

 the marine environment for several years. In their beach studies, the 

 experiments have generally been carried out between the high- and low- tide 

 line. In a recent study (Stuiver and Purpura, 1969) , material was in- 

 jected as a band 50 feet wide from the high-tide line to the low-tide 

 line with additional sand placed in water-soluble bags to a 3-foot depth. 

 Samples were obtained along ranges spaced 500 feet apart; three samples 

 were collected along each range. After the samples dried, they were split 

 into 100-gram parts which were then counted to give the concentration of 

 fluorescent particles as the function of distance from the injection line. 

 The experiment lasted about 45 days, and samples of tagged sand were 

 obtained as far as 5,000 feet downcoast. In addition to the studies 

 at the beach, the University of Florida scientists studied sediment 



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