A procedure for tracing of kraft mill effluent from an ocean outfall by constituent fluorescence

WATER pollution control agencies are concerned with tracing pollutants discharged from ocean outfalls for the following reasons: (1) the information obtained on the concentration distribution in the environment can be used to improve the fundamental understanding of dispersion and will lead to improved methods for designing ocean outfalls; and (2) as a means of surveillance activities to assure that operating systems are meeting water quality requirements. Several methods are available for performing this task which have utility for both objectives. HhRREMO~S (1966) used radioactive bromine for tracing drift plumes which developed below the surface. Rhodamine dye has been used by a number of investigators (BAUMGARTNER et al., 1969; STEWART et al., 1969). Coliform bacteria have also been used (FoxWORTHY and KNEELING, 1969), either alone or with an additional tracer such as rhodamine, to aid in correcting the coliform counts which are influenced not only by dilution, but also by variable regrowth and die-offpatterns. One objection to the use of rhodamine is on the basis of its cost, because the useful technical attributes are well recognized (ANON, 1968). Assume that in a typical plume study, a minimum rhodamine WT concentration desired at the initial point in the study is 10 parts per billion by weight (ppb). If dilution on the order of 100 times will be achieved in the vertical rise of the waste from the diffuser to the surface, the amount of stock rhodamine solution which must be added to the pipeline is 13 ml of 20 per cent rhodamine per minute per million gallons per day (mgd) of waste flow. Hence, for a study of a 10 mgd discharge over a 10-h period, 20 gal. of 20 per cent rhodamine would be required; at a cost of $10 per gallon in 50 gal. drums, this would amount to an expenditure of $200. The limitations for the use of radionuclides, in addition to the cost, are the special equipment required for counting, the problem of dosing with high energy stock solutions, the licensing requirement of state and federal regulations, and the local public concern. The most desirable situation is to find some constituent of the waste stream itself which, because it is either conservative or the rate of decay is well established, can be used as a tracer.