and others, 1983). The concentrations of trace 
metals and hydrocarbons in commercially impor- 
tant species of fish and shellfish on Georges Bank 
have been determined in ongoing programs con- 
ducted by the National Oceanic and Atmospheric 
Administration (Cooper and others, 1981; Cooper 
and others, 1983). This report is based on data 
generated by the USGS during all 3 years of the 
program. Only the data generated in the third year 
is tabulated in this report. Tabulation and inter- 
pretation of data obtained during year 1 and year 
2 are contained in the final reports for each year 
(Bothner and others, 1984a, b). 
The first cruise of the monitoring program 
occurred just before exploratory drilling com- 
menced in July 1981, and subsequent cruises have 
been conducted on a seasonal basis (November, 
February, May, and July) over a 3-year period. On 
each cruise, samples were collected at regional sta- 
tions 1-8 (fig. 1A) and at 29 site-specific stations 
(fig. 1B). Regional stations 19, 20, and 21 were 
added to the program during the July 1983 cruise. 
Locations indicated by a triangle on figure 1A are 
sites of sediment cores that were taken on other 
cruises during the postdrilling period. The 18 
regional stations were positioned to evaluate 
changes with time over different environments 
within the entire region. For example, stations 13 
and 13A are thought to be areas of deposition for 
material winnowed by currents from Georges Bank 
(Bothner and others, 1981; Twichell and others, 
1981), as are stations 14 and 14A in the Gulf of 
Maine and stations 7A and 9 in the heads of 
Lydonia and Oceanographer Canyons. Station 15 
is in an area of eroding coarse sediment. Given the 
mean current flow to the west on the southern 
flank of Georges Bank (Butman and others, 1982a), 
the stations in transect I (stations 1, 2, and 3) are 
considered to be upstream controls for stations 
among the major lease blocks (transect II) and for 
stations downstream of the lease blocks (transect 
III). (Station 13A was added on cruise 4. Because 
the sediment texture varied considerably over 
short distances at stations 7 and 14, the positions 
were changed in the second year of the program 
to locations labeled 7A and 144A; see fig. 1A. Sta- 
tions 15 and 14A were discontinued after the 
eighth and ninth cruises, respectively.) 
The site-specific survey, designed to monitor 
changes close to a rig, was centered around the 
platform operated by Mobil in block 312 (regional 
station 5), where drilling took place between 
December 1981 and June 1982. A less detailed 
local survey was conducted with three stations 
(regional stations 16, 17, and 18) near the Shell Oil 
Company platform that operated in block 410 be- 
tween July 1981 and March 1982. 
Hight exploratory wells have been drilled to date 
on Georges Bank. The first was started on July 22, 
1981, and the last well was completed on Septem- 
ber 27, 1982. Each of the exploratory wells was 
classified as a dry hole with no commercial quan- 
tities of hydrocarbons. There has been no addi- 
tional drilling on Georges Bank in the period be- 
tween September 27, 1982, and February 15, 1985. 
FIELD SAMPLING AND SAMPLE PREPARATION 
Positioning of the ship on each monitoring cruise 
was based on the Loran-C navigation network. A 
Northstar 6000 (Digital Marine Equipment Corp., 
Bedford, Mass.) receiver was used to read time 
delays and to calculate latitude and longitude. The 
latitude and longitude values reported in this paper 
are not as accurate as those calculated by using 
a more modern algorithm, and workers who wish 
to plot or to reoccupy the stations of this program 
should rely on the time-delay values rather than 
the latitude and longitude. Samples were collected 
when the ship was within +0.3 us of the target 
time delays for each station. At station 5, for exam- 
ple, +0.3 us converts to an error in positioning of 
+140 m drms (distance root mean square; see 
Bowditch, 1977, p. 1231). Navigation data for each 
sample analyzed for chemistry are compiled in 
appendix tables 1A-1C. 
Special steps were taken to minimize contamina- 
tion of sediment samples at sea. The samples for 
chemical analyses were collected with a 0.1-m? 
stainless steel Van Veen grab sampler with teflon 
coating on all surfaces in contact with sediment. 
A polyethylene-coated cable was used to lower the 
grab to the sea floor. Upon recovery of a sample, 
the overlying water was siphoned off with a glass 
tube, and the upper 2 cm of material was (1) col- 
lected with a noncontaminating utensil, (2) placed 
in an acid-washed polyethylene container, and (3) 
frozen until analyzed. Because individual grab 
samples were subsampled for both trace-metal and 
hydrocarbon analyses, the grab sampler was rinsed 
with distilled methanol and hexane before each use. 
Sediment cores were collected on other USGS 
cruises in the study area with a hydraulically 
damped gravity corer similar to the one described 
by Pamatmat (1971). This apparatus has a slow 
rate of penetration controlled by a water-filled 
piston, and it collects cores as long as 70 cm (in 
