content in the Svisloch River are given in Figure 2. Above the source of 

 pollution (Stations 1 and 2), the fraction of chlorophyll in the seston 

 made up 0.2 percent. In the polluted zone (Stations 3, 4, and 5), it 

 dropped to hundredths of a percent. Downstream, the processes of self- 

 purification lead to a considerable increase in the chlorophyll content 

 in the seston. 



Specific Oxygen Consumption (SOC) is an 

 characterizing the biological activity of s 

 amount of oxygen consumed by a unit mass of 

 According to Hargrave (1972) SOC values for 

 gin, composition and degree of dispersion 1 

 0.240 mg 02/mg organic matter per day. Whi 

 are apparent, for many scientific and pract 

 evaluation of water pollution, it is necess 

 this index depends on the trophic status an 

 this regard, a determination of SOC by sest 

 various types polluted to varying extent by 

 sewage. 



important functional index, 

 eston. It represents the 



suspension, per unit time. 



suspensions of various ori- 

 ie within a range of 0.002- 

 le the relative values of SOC 

 ical purposes, including the 

 ary to fully understand how 

 d the pollution degree. In 

 on has been made on lakes of 



domestic and industrial 



0.3 



-1 0.4 



> 



x 



Q. 

 O 

 DC 



O 



_l 



X 



CJ H 

 LU ^ 



> H 0.2 



< 



LU 

 DC 



I- 



LU 



o 



DC 

 LU 

 Q_ 



O 



STATIONS: 



1 AND 2 ARE ABOVE THE ZONE OF POLLUTION 



3, 4 AND 5 ARE IN THE ZONE OF ACTIVE DECOMPOSITION 



6, 7 AND 8 ARE IN THE ZONE OF RECOVERY 



0.1 - 







2 3 4 5 6 



SVISLOCH RIVER STATION 



Figure 2. Relative chlorophyll content in seston of the River Svisloch 



in June of 1973. 



153 



