Lake Michigan environmental survey : final report / [edited] by John C. Ayers.

CHAPTER B

NEUTRON ACTIVATION AND ATOMIC ABSORPTION ANALYSIS
Richard Copeland and Ronald Rossmann
FIELD METHODS
Metal-free collecting techniques were employed during the cruises of
1969 and 1970. Metal-free techniques are a prerequisite to the subsequent
analysis of trace elements. The samples taken by the metal-free methods
were water, bottom sediments, benthos, phytoplankton, and zooplankton.
The equipment used for metal-free collection included water sampling
apparatus rigged on the ship's bowsprit, a ponar dredge, # 000, # 5, # 20
plankton nets, synthetic line, assorted pieces of nylon stocking, large
and small plastic spoons, plastic funnels, plastic bags, plastic bottles,
plastic buckets, large plastic garbage pails, plastic mats, plastic bottles
filled with sand for use as weights, a metal-free pump and hoses, fiberglass tubs, and a plastic coated underwater sled.
The water sampling apparatus consisted of a plastic pulley mounted on
the forward end of the bowsprit and several yards of light synthetic line
running around the pulley and back to the bow of the ship. A water sampling
bottle and a metal-free weight were attached to the line and heaved forward.
Manipulation of the line maintained the sampling bottle at the proper depth
(ca. 2 ft) and at maximum distance from the ship's hull. The forward position of the sampling rig permitted collection of water which had not come in
contact with the ship's hull.
Water sampling commenced immediately upon arrival at a station. The
sampling bottles were filled and taken to the ship's lab where the water was
filtered using glass and plastic apparatus and the filtered water was acidified and stored in plastic bottles. The filters were handled with plastic
forceps. After each filtration, the filters were placed in a plastic bag and
frozen and the filtering apparatus was rinsed with concentrated nitric acid.
Sediment samples were taken with a ponar dredge. The sediments were deposited on a large plastic mat and samples from the center portion that had
not touched the dredge were transferred to plastic bags with a plastic spoon.

B-L