OIL AND TAR POLLUTION OF WATEES. 5 



shallow water vegetation which directly or indirectly furnishes fish 

 food and shelter; and by impairment of the market value of fish 

 through imparting to them an offensive taste. 



DIRECT TOXIC EFFECTS. 



A great variety of tars and tar oils, either from coal or petroleum, 

 have been shown to be highly poisonous. Butterfield and writers 

 in the (London) Fishing Gazette and the Salmon and Trout Maga- 

 zine, and Shelford and Thomas in this country (see bibliography) 

 have reported various experiments which show that tar and tar 

 oils are poisonous in great dilutions. Tars or tar oils result from 

 distillations of coal, petroleum, woods, etc. These distillation 

 products are very complex and varying in composition, but all may 

 be assumed to contain some of the substances which, in very weak 

 dilutions, have been shown to be highly poisonous to various fishes. 

 Phenols and cresols (in dilutions of less than 100 parts per million) 

 have been found quickly fatal by Butterfield and Shelford. Other 

 constituents which are quickly fatal in the dilutions indicated are 

 phenanthene and naphthalene (4 to 5 parts per million) ; xylene, 

 toluene, benzene , and ethylene (22 to 65 parts per million) • sulphur 

 compounds, as hydrogen sulphide (5 parts per million), sulphur 

 dioxide (16 parts per million); carbon bisulphide (100 parts per 

 million) ; thiophene (27 parts per million) ; ammonia (7 parts per 

 million) ; and ammonium salts and other nitrogenized compounds 

 (some hundred parts per miUion) ; tiuinoline and isoquinoline (50 to 

 65 parts per million). The strengths given as ciuickly fatal are those 

 which have caused death in one hour, or very little more, to sunfish 

 (American) or gudgeon (European), fish which seem more than ordi- 

 narily resistant to poisons. It is stated (Seydel) that Russian 

 investigators find hexahvdrobenzoic acid (C„HnCO.CH), to be the 

 essential poison of Russian petroleum, and that 4 to 16 parts per 

 million were quickly fatal to a cyprinid and a percid. 



The experiments of Thomas and others indicate that prolonged 

 exposure to very much greater dilutions of these substances are 

 fatal. Dilutions of various tars and crude distillates of petroleum, 

 which required 66 or more parts per million for quick fatality, have 

 proved fatal in strengths of from 13 to 33 parts per million in from 

 1 to 3 days. A great variety at 13 parts per million proved fatal in 

 3 days. One liquid tar waste at 2 parts per million killed sunfish 

 (Lepomis humilu) in one day. 



MECHANICAL EFFECTS. 



Certain petroleum products appear to contain no poisonous sub- 

 stances soluble in water and to liavo little direct efrert when allowed 

 to form a surface film, but when cmulsi(icd by agitation prove deadly. 

 A high-boiling petroleum distillate and a light fuel oil wore found Ijy 

 Thomas to be quite harmless, unless as aeration retarders, or unless 

 emulsified, as by continued moderate agitation, when they coated 

 the gill membranes of the lish and caused <l<^ath by suffocation. 

 Rushton found that by shaking up 1 pjirt of benzine with 40,000 parts 

 of water, a mixture was formecl which killed (i-ih in five minutes, 

 appartjiitly eritiroly from poisonous action. 

 68637*— 21 2 



