NATIONAL OCEANOGRAPHIC PROGRAM—1965 417 
Sediments with the highest immediate oxygen demand had the greatest organic 
content. Laboratory studies on Lake Erie sediments showed that large amounts 
of iron and phosphorus are released into the water from the sediments when 
the oxygen content of the water dropped below 1 ppm. 
The sampling efficiencies of the Petersen, orange-peel, and Smith- 
McIntyre dredges in relation to water depth and bottom type in Lake Michigan 
have been compared. Three samples were taken with each dredge at depths of 
3, 10, 20, 30, and 40 fathoms along each of four transects. Data from this 
undertaking have not been analyzed fully. However, a comparison made in 1960 
of the Petersen and Smith-McIntyre dredges showed that both collected about the 
same number of organisms from bottoms shallower than 15 fathoms. The Petersen 
dredge collected fewer organisms at each subsequent 5-fathom increase in 
depth whereas the Smith-McIntyre collected about the same numbers at all depths 
from 15 to 30 fathoms. These results cast doubt on the validity of much of 
the data on abundance of benthic organisms in the deeper waters of the Great 
Lakes. 
We have started to investigate the nature and concentrations of organic 
nutrients in Great Lake: waters. ALthouzh developments of sampling procedures 
and methods for identifyins organic compounds are of immediate concern, 
nevertheless, we are usinjyy activated charcoal filters to adsorb and concen-= 
trate the organics in water. A filter unit is in operation at Hammond Bay, 
Lake Huron, and a similar unit was installed aboard the M/V Cisco during 1961. 
Spectrophotometric (ultraviolet, infrared), polarographic, and radiographic 
methods are being investigated for identifying the organics. Standard 
methods for detecting alkyl-benzene-sulfonants (detergents), tanin, and lignin 
will be employed to study the interrelationships between these major organic 
groups. An adsorption column assembly has been constructed to study several 
physical variables such as column size and flow rate. 
The organic compounds are extracted from the activated charcoal with 
chloroform and alcohol. Amounts of choloroform and alcohol extractables ap- 
pear to be useful for indicating relative water qualities. Chloroform ex- 
tractables are assumed to represent less polar compounds of industrial 
origin (pollution) and alcohol extractables the more polar varieties from 
humic acid (natural organics), etc. These criterin indicate that the waters 
of northern Lake Michigan and in the vicinity of Iluwanond Bay, Lake Iuron, 
are "clean" waters. The limnectic waters of Late Michigan had a particularly 
high ratio of alcohol to chloroform extractables. This ratio indicates a 
seasonal fluctuation when monthly samples are compared. 
35-377 O—64—— 28 
