1340
I N D U S T R I A L A N D ENGINEERING CHEMISTRY
the lake samples. I n the bottom samples the numbers exceeded 100 per cubic centimeter in the Genesee River waters and in an area less than three-quarters of a mile in radius around the outfall. The bottom waters between the outlet and the shore showed lower numbers than the shore samples. The average numbers of organisms of the coli-aerogenes group as shown by the count on eosin methylene blue agar in the top and bottom waters were similar to those found by the presumptive test, except that the average result for the bottom sample at the effluent outlet was much larger in the case of the count on eosin methylene blue agar. The dissolved-oxygen determinations showed that the lake waters were saturated with oxygen. Summary and Conclusions
Samples collected near the sewer outlet and samples of Genesee River water were the only ones in which the numbers - of bacteria of the coli-aerogenes group were in excess of 100 per cubic centimeter. I n a few cases numbers of such bac-
Vol. 22, No. 12
teria in the vicinity of 100 per cubic centimeter were found in samples taken along the shore. I n those cases, however, the bacteria evidently were due very largely to violent wave action upon the banks and shores. The bacterial analyses showed no movement of sewage pollution in well-defined currents in the lake. There was evidence of a general easterly flow of river water toward the beaches east of the river mouth. This flow may have resulted in some of the bacteria from the river being carried to these beaches. There is some indication of a tendency for the sewage effluent also to be carried in an easterly direction. The bacterial results demonstrate the great ability of the lake for diluting and dispersing the effluent discharged from the outlet. The results show that for the summer of 1929 there was relatively little bacterial pollution a t any of the beaches. A consideration of all the conditions led to the conclusion that the health hazard attending bathing a t the several beaches of Rochester during the summer of 1929 was negligible.
Some Observations of the Effect of Pollution Contributed to Streams' J. K. Hoskins and H. R. Crohurst U. S. PUBLICHEALTHSEXVICZ, CINCINNATI, 0x10
A resurvey of the pollution of the Ohio River between past and present conditions RESURVEY of the Cincinnati and Louisville during the past year gave with the river flowing in pollution of the Ohio data for comparison with results obtained in 1914, open channel, and a summer River b e t w e e n Cin1915, and 1916 prior to the completion of many of the period, when the velocity of cinnati and Louisville has dams on the river. The river at Cincinnati appears flow is i n f l u e n c e d by the been in progress by the U. S. to have been in better condition except for available o p e r a t i o n of n a v i g a t i on Public Health Service during dissolved oxygen than at the time of the previous indams; the past summer r e p the past year. This study vestigation. r e s e n t i n g a period of exhas been u n d e r t a k e n for ceedingly low stream flow the purpose of ascertaining the extent to which increasing population and industrial with the navigation dams continuously in operation since activity on a large watershed is reflected in the sanitary May. Sampling stations were re-opened at Mile 461, above Cincondition of the receiving stream, and also of determining the effect produced by complete canalization of the river cinnati a t the water-works intake; a t Mile 475, immediately by means of a succession of pools at low water stages. below the city and above Dam No. 37, which forms the The present investigation has made available chemical and Cincinnati pool; and a t Mile 488, which is 7 miles below this bacteriological information for comparison with similar data dam. Samples have also been collected from the Little collected during the first survey in 1914, 1915, and 1916, Miami and Licking Rivers, which enter the main stream within this stretch. prior to the completion of many of the river dams. The drainage area of the Ohio River, above the Cincinnati water-works intake, is 70,950 square miles and supports a Seasonal Variation in Oxygen Balance and Bacterial Load population of varied industrial, agricultural, and mining purI n Table I, the chemical and bacteriological findings for the suits which in 1915 totaled 7 million. Of this total, 2.9 previous and present investigation a t main river and tributary million lived in urban communities and were mostly sewered. sampling stations in the vicinity of Cincinnati have been To this must be added the equivalent population of industry, summarized as winter and summer averages. The dissolvedwhich exceeded in effect that of the domestic sewered popula- oxygen and biochemical oxygen demand are presented as tion itself. Present population statistics are not available, daily averages in pounds of available and required oxygen, but must be in considerable excess of those determined for respectively; the bacteriological results in terms of quantity 1915. units, the product of the discharge in thousands of second feet, I n the following brief discussion an attempt has been made, and the bacteria per cubic centimeter. in so far as the data are at present available, to compare the Confirming previous studies, Table I indicates a marked sanitary condition of the Ohio River, within the Cincinnati seasonal variation in the chemical and bacteriological content metropolitan area, at the time of the previous investigation, of the river water. I n winter the water carries greater 1914 to 1916, inclusive, with conditions a t the present time. amounts of dissolved oxygen, but the oxygen demand is also The data have been divided into a winter period representing higher than in the summer, The ratio of available to required oxygen was higher in the summer a t the time of the 1 Received September 20, 1930.
A
INDUSTRIAL AND ENGINEERING CHEMISTRY
December, 1930
Table I-Chemical
I YEAR
I
and Bacteriological Data for Sampling Stations in Vicinity of Cincinnati
I
WINTERPERIOD Dissolved oxygen
Lbs.
1341
Oxygen demand
Lbs.
I
SUMMER PERIOD
I
BACTERIA
370 c. aear
Dissolved oxygen
Coliaeroeenes
Quantity units
Oxygen demand
Lbs.
BACTERIA
37" c. aear
ColiILPTOPPtlPS
Quantity units
Lbs.
S T A T I O N NO. 461
1913-14 1914-15 1915-16 Average 1929-30
9,182,470
3,119,220
9,182,470 10,862,800
3,119,220 1,818,298
126,859 306,950 491,960 325,110 270,225
4,126 7,151 4,860 5,493 11,552
719,250
142,550
719,250 536,912
142,550 105,943
KO d a t a
No d a t a
12,661 167,382 62,827 82,605 32,825
207 5,270 675 2,175 489
1,758 39,438 3,597 16,961 46,648
118 349 66 188 1,232
LITTLE MIAMI R I V E R
1913-14 1914-15 1915-16 Average 1929-30
398,264
119,454
398,264 260,205
119,454 62,880
12,450 21,859 69,045 36,450 32,425
129 367 632
~
~~
LICKING RIVER
1913-14 1914-15 1915-16 Average 1929-30
514,050
195,390
514,050 424.705
195,390 83.760
15,079 55,197 69,197 49,350 19.957
724 334
18,407
8,605
18,407 19.761
8,605 6.685
674,856
278,202
574,586 490.052
278,202 180.780
640,410
220,701
640,410 527,503
220,701 150,997
4,260 56,940 11,694 25,445 7.373
141 1,613 296 718
3,681,900 3,093,480 3,439,300 3,401,750 1,479,200
103,250 129,920 50,610 98,600 17.120
744,270 2,926,320 2,520,430 2,022,180 1,224,100
28,040 83,567 49,850 54,180 9,188
97.5
S T A T I O N NO. 476
1913-14 1914-15 1915-16 Average 1929-30
10,285,400
5,028,522
10,285,400 11,551,500
5,028,522 2,272,100
392,912 873,774 896,192 750,782 880,110
21,180 46,006 28,643 32,922 28,572
I
I
S T A T I O N NO. 488
1913-14 1914-15 1915-16 Average 1929-30
10,235,700
4,469,830
10,235,700 11,357,780
4,469,830 1,826,540
1,229,460 772,080 1,000,770 545,090
14,435 23,980 19,210 21,150
previous investigation but a t present it is lower. The bacterial load above Cincinnati and in the less polluted Licking River is greater in winter than in summer, but at the more polluted points below Cincinnati and in the Little Miami River the reverse is true. Comparison of the winter results of the past and present study shows greater amounts of dissolved oxygen and a smaller biochemical oxygen demand during the winter of 1930 than during that of 1914. The tributaries show less dissolved oxygen and a decrease in oxygen demand during the winter of 1930, the ratio of the available to the required oxygen being greater in 1930 than in 1914. The bacteriological data indicate smaller numbers of 37" C. organisms during the winter of 1930, at tributary and main river sampling stations above and below Cincinnati, but a tendency toward higher numbers of organisms of the coli-aerogenes group above the city and on the Little Miami River, the increase being greatest immediately above Cincinnati. The summer data indicate smaller amounts of dissolved oxygen in 1930 as compared with 1914, but the ratio of the available to the required oxygen was practically the same in both summer periods. Bacteriological data reveal a decrease in bacterial load a t all main river stations during the summer of 1930. The Little Miami River showed increased numbers of both 37" C. and coli-aerogenes organisms in the summer of 1930, the Licking smaller numbers of 37" C. organisms and greater numbers of coli-aerogenes.
increased somewhat, both in the main stream and in the Little Miami River, since the previous study. With minimum stream flows during the past summer the dissolved-oxygen content below Cincinnati has been seriously reduced and, a t times, entirely depleted. At this same sampling station (No. 475) the oxygen demand has been less than during the previous study and decreases in numbers of both 37 O C. and coli-aerogenes organisms have been observed, resulting, it is believed, from lower velocities in the river with consequent increased sedimentation. On the tributaries, the oxygen conditions appear to have improved, but the bacterial load in general is greater than a t the time of the previous study. Table 11-Per-Capita Changes during the Winter and Summer Seasons, in the Oxygen Balanc;? and Bacterial Content of the Ohio River, below Cincinnati
I
WINTERPERIOD
I
SUMXER PERIOD
PER-CAPITA CHANGE IN:
YEAR Oxygen
-balance
37' C. ColiOxygen organisms aerogenes balance
Quantity units" 1914 1915 1916 Average 1930
3.24
0.507
0.483 0.993 0.538
0.034 0.076 0.048
0.687 0.797
0.053 0.027
37' C. Coliorganisms aerogenes
Quantity units 0.587
0.222
7.41 5.73 6.80
0.208 0.248 0.100
6.64 2.30
0.193 0.024
a One bacterial quantity unit = 2 446 589 000 000 bacteria per day. Note-Sewered population Cincinnati metrdpolitan area, 1915, 494 000, 1030, 605,000.
Discussion of Data
Summarizing the data thus far available, the Ohio River a t Cincinnati appears to have been in better condition, except for available dissolved oxygen, than a t the time of the previous investigation fifteen years ago. During the past winter improved oxygen conditions have existed and the bacterial load, as indicated by the 37 " C. organisms, has been generally less, although organisms of the coli-aerogenes group appear to have
The effect, on a stream, of the pollution contributed by a community should be indicated by changes in oxygen conditions and by the increase in bacterial load between sampling stations on the river above and below the community in question. I n Table I1 the data of Table I have been summarized to show the per-capita seasonal changes in oxygen balance and the increase in bacterial load, in the Ohio River below Cincinnati, based on the sewered population in 1915 and 1930.
INDUSTRIAL AND ENGINEERING CHEMISTRY
1342
The data indicate, in the winter period, greater per-capita changes in oxygen balance and lower per-capita contributions of bacteria. The 1930 per-capita contributions in both summer and winter, with the exception of the 37" C. organisms in winter, are less than in the years of the previous investigation. The indicated decrease in the per-capita contribution of bacteria during the past summer is believed to be due, as already suggested, to processes of natural stream purification resulting from increased times of flow past Cincinnati during pool stage. Monthly Changes in Oxygen Balance
I n order that more data might be available to determine any seasonal variation in the per-capita oxygen balance past Cincinnati, the average monthly changes have been calculated from the 1930 data and are arranged by months in the order of increasing stream flow, in Table 111. Table 111-Calculated Monthly Average Per-Capita Changes in Oxygen Balance below Cincinnati, September, 1929, t o July, 1930, Inc1u si v e PER-CAPITA CHANGEIN OXYGENBALANCE
DISCKARGB
MONTH
Second-feet 3,400 9,000 9,500 25,200 65,100 103,300 130,000 138,600 158,600 2 12,000 212,900
July September
June
May October April December February November January March
Lbs. 0.184 0.198 0.225 0.300 1.670 0.754 0.993 0.267 1.258 0.679 0.269
Vol. 22, No. 12
At least two possibilities seem to be suggested-errors in the calculations due to errors in stream-flow measurements, combined with errors in the oxygen determinations, or a material contribution of oxygen demand from other than the sewered population, with the inflow of surface run-off. Assuming a possible error of 10 per cent in the stream-flow measurements and an error of 0.05 p. p. m. in the oxygen-de mand determination, a cumulative error varying from 10 to 50 per cent is possible with stream flows of 5000 to 200,000 second-feet, respectively, in calculating the oxygen demand from a sewered population of 605,000-that of the Cincinnati metropolitan area. I n order to compare variations in rates of run-off with the oxygen demand of streams, several watersheds were selected which were essentially rural in character above the sampling points at which the calculations were made. The monthly average oxygen demand, in pounds per square mile, and the discharge, in second-feet per square mile, was calculated for each of these areas. The data are summarized in Figure 1 and indicate an increase in oxygen demand with increased rates of run-off. I n Table IV the discharge and corresponding calculated oxygen demand, both per square mile of watershed, have been separated into periods of high and low run-off, to indicate the difference in oxygen demand present in the stream under these extremes of conditions. The oxygen demand present during periods of higher run-off varies from five up to twentytwo times that of the low-water period, the average for the high-water period being twelve times that of the low-water period. Table IV-Comparison between Discharge and Oxygen Demand during Periods of High and Low Run-Off from Rural Watersheds 5-DAY B. 0. D.
AVERAGE DISCHARGE 301
1
I
I
c
--..
I
.
WATERSHED
I
*
-7Minnesota River Licking River Zumbro River Mississippi (above Minneapolis) Spoon River Mackinaw River Kankakee River Ohio (above Cincinnati) St. Croix River
Low-water months
High-water months
Sec-ft. per sq. mi. 0.040 0.462 0,089 1.87 0.582 0.107 0.120 0,1375 0.1376 0.185 0.216 0.309
Low-water High-water months months
1
Lbs. per sq. mi. 0.348 6.63 1.854 40.31 5.37 0.911
0.5S7 0.818 1.608 1.566
0.754 2.022 1.609
1.560
6.66 16.62 20.78 20.37
1,900 1.273
2.750 2.29
38.1 10.86
Copclueion
.o/
I
5
10
/5
BO
85
30
F / V E OAY B / O C f f € M / C A L O X Y G E N DEMAND (POUNDS P F . ~D A Y PER SQUAREM / L E )
Figure 1-Relation between Estimated Discharge, Second-Feet per Square Mile, and Calculated 5-Day Biochemical Oxygen Demand Pounds per Square Mile, o n Water sheds Essentially Rural'in Character
These data, supported by data from other stream-pollution studies, suggest that the effect of pollution from a community can be more accurately ascertained from the oxygen data when the volume of the receiving water is small, as during summer, with less precipitation on the watershed, or in the winter months when the precipitation is held on the drainage area in the form of ice and snow and the stream flow consists largely of ground-water infiltration.
I n view of the data thus far collected in the resurvey of the Ohio River, supported by data from other stream-pollution studies, the results of the application of the biochemical oxygen demand test in interpreting the effect of a sewered population the size of that of the Cincinnati metropolitan area, on the Ohio River, may be influenced to such an extent by errors in stream-flow measurements and in the oxygendemand determination itself, or by the oxygen demand contributed with the run-off from the watershed, as to lead to erroneous conclusions. The data thus far available seem to indicate that the most accurate analysis of the chemical, hydrometric, and sewered population data will result when the flow of the receiving stream approaches a minimum, as during the summer months, or, in the case of northern watersheds, during the winter period when the discharge from the drainage area is also a minimum and the stream flow made up largely by contributions of ground water. For the intermediate periods of spring and fall there yet remains to determine the extent of the "normal" oxygen demand contributed by a watershed, in order to estimate the effect of that contributed through artificial drainage systems.
