WATER ANALYSIS--Determination of mercury in water


                                           July l5, 1970

QUALITY OF WATER BRANCH TECHNICAL MEMORANDUM 71.01

To:      Regional Hydrologists and District Chiefs, WRD

From:    Chief, Quality of Water Branch, WRD

Subject: WATER ANALYSIS--Determination of mercury in water

In response to QW Branch Technical Memorandum No. 70.12, 
May 19, 1970, a number of district offices have submitted 
water samples for mercury analysis, mostly from river sites 
where the presence of mercury was suspected. The sampling 
sites were selected after discussion with either FWQA or 
State authorities. The samples were sent directly to the 
Methods Development Unit, Denver, Colorado, where they were 
analyzed for dissolved mercury by Marvin Fishman with a 
recently adapted method using a silver wire cell and the 
atomic absorption spectrophotometer.

Grab samples of the water-sediment mixture were filtered at 
the time of collection through 0.45 micron filter and the 
filtrate acidified with about 1.5 ml concentrated nitric acid 
per liter of sample. Either polyethylene or glass containers 
were used. The following is a summary of the results:

Number of samples analyzed: 73 
Number of sampling sites: 72 
Number of States included: 31 
Range in concentration - Less than 0.1 to 17 
  ug/l (parts per billion) 
Statistical grouping of mercury concentrations: 
  Less than 0.1 ug/l -    34 
  O.l to l.O ug/l -       27 
  1.1 to 5.0 ug/l -       10 
  greater than 5.0 ug/1 -  2*
                         ___
                          73


*5. 0 ug/l is the U. S. Public Health Service tentative 
proposed standard or upper limit for mercury in drinking 
water.

The above results represent only concentrations in the 
dissolved phase, because the silver wire cell method is not 
applicable to mercury that may be adsorbed on sediments. 
However, a detectable amount of mercury in solution is a 
fairly good indicator that suspended sediment in the stream 
also may be mercury bearing. We are currently trying to 
determine the amount of mercury associated with suspended 
sediment through neutron activation analysis, in which the 
whole water sample (water plus sediment) is irradiated in the 
TRIGA Reactor in Building 15, Denver Federal Center. 
Mr. Thatcher expects to have some preliminary results soon.

Results will be collated as received, in order to establish a 
baseline of data on mercury in water resources. Sources will 
be identified as natural or man-made where this can be done.

Some districts, such as Florida, already have completed 
State-wide reconnaissance surveys for mercury, and other 
districts are encouraged to do so in consultation with FWQA 
and State officials,,

Summary

In view of the mounting evidence of mercury occurrence in the 
environment (about one-half of the results reported in this 
summary have dissolved mercury in detectable amounts, above 
0.1 ,ug/l), it is recommended that districts begin a limited 
reconnaissance of mercury in water at key water-quality sites 
to establish a baseline of relations between natural and man-
made sources of mercury. Suitable procedures also should be 
developed to examine the whole water sample (dissolved plus 
suspended sediment) and bed-material samples to establish the 
total amount of mercury in various phases of the hydrologic 
environment.


                                   W. H. Durum
Attachment
WRD Distribution:
A, B, S, FO