Proceedings of the Tomsk Technological Institute of Emperor Nicholas II.
Vol. XXIV, 1911, No. 4.

Study of the Chemical Composition of Atmospheric Precipitation in Tomsk in the Winter of 1909–10, Depending on Meteorological Factors.

Diploma thesis by students of the engineering-construction department, A. Bykov and K. Karpov.

The present work was carried out at the meteorological station of the physical laboratory of the Tomsk Technological Institute at the suggestion of Professor B. P. Weinberg, to whom the authors are indebted for his supervision of the work and for providing the scientific means for carrying it out. The authors of the work also made use of the valuable guidance of Professor D. P. Turbaba and instructors A. V. Ignat’ev, S. M. Filatov, and S. V. Lebedev.

For collecting atmospheric precipitation, we installed a glass vessel on the tower of the Institute’s physics building. In addition, several analyses were made of precipitation collected by special glass vessels on the outskirts of the city, far from dwellings and buildings. The vessels were kept open, since closing them is inconvenient in that it can lead to the loss of the first portion of falling precipitation, as it is very difficult to catch the moment when it begins to fall. However, so that accidental dust and soot present in the air would nevertheless not affect the chemical composition of the precipitation, the vessels were washed almost daily with distilled water. The amount of precipitation collected by our vessels was not measured, since for this purpose it was possible to use the data of the Institute’s meteorological station. Precipitation that fell during the day was collected, as far as possible, soon after it had fallen; precipitation that fell at night was collected at 10 o’clock in the morning.

Of all the compounds occurring in meteoric water, we studied ammonia (NH₃), nitrous acid (NO₂H), and nitric acid (NO₃H), in view of their importance in agriculture. In choosing methods for the quantitative determination of NH₃, NO₂H, and NO₃H, we settled on the methods that had been used for the same purposes at the observatory in Montsouris and by A. Pozdnyakov¹) at the magneto-me—

¹) “An Experiment in Studying the Chemical Composition of Precipitation in Relation to Meteorological Factors”—Journal of Experimental Agronomy, 5, 740, 1904.

…of the meteorological observatory of Novorossiysk University, in view of the fact that uniformity of methods is the best condition for comparability of results.

The methods we used are described in sufficient detail in A. Pozdnyakov’s article, and therefore we shall confine ourselves to listing them. For the quantitative determination of ammonia we used the methods of Frankland and Armstrong with Nessler’s reagent; for the quantitative determination of nitrous acid—the Griess method¹; for the quantitative determination of nitric acid—the methods of Grandval and Lajoux².

The titer was established by a colorimetric method with variable volumes of the normal and the solution being compared. Having at our disposal neither a Duboscq colorimeter nor Hehner cylinders, which are commonly used in investigations of this kind, we used simple test tubes of identical diameter and height, placed in a special dark colorimetric chamber, and achieved equality of coloration by simply pouring off or adding the corresponding liquid, measuring the thickness of their layers with a scale. The chamber (Fig. 1) had 8 compartments for placing test tubes with typical liquids of various definite concentrations and test tubes with the liquids under investigation. When the chamber was illuminated from below by light diffused from white paper, it became possible to detect very small differences in the intensity of coloration and thus to determine rather accurately the content of the substance under investigation in the solution.

Analyses of falling atmospheric precipitation were carried out from February 1 to May 10, 1910 (old style). The period from September 26, 1909, to February 1, 1910, was spent on preparatory work, on learning the methods of quantitative analysis of water in the quantitative-analysis laboratory and in the laboratory of nutrients of the Institute, on preparing normal solutions and reagents, on equipping the appropriate laboratory, etc.

In all, precipitation collected in vessels on the tower of the physics building was investigated—37 samples, and precipitation collected in vessels placed outside the city—5; thus, in total, 42 observations. In addition, attempts were made to collect snow in wooden boxes painted with ocher; 5 analyses were made of such snow, collected on 3 occasions.

...on the tower of the Institute and in 2 cases outside the city, showed that the wood and paint affect the increase in the content of the compounds under study in meteoric water, and therefore the attempt to collect snow in wooden boxes was abandoned.

Leaving aside for the time being the consideration of studies of precipitation collected outside the city and in wooden boxes, we shall subject to detailed examination only the systematic analyses (37) of precipitation collected in glass vessels on the tower of the physical building of the Institute.

According to the data of the meteorological station of the Institute, for the period from February 1 to May 10, 1910 (old style), 44 cases of precipitation were recorded, so that we did not investigate only 7 cases, namely those when the precipitation fell in very insignificant quantities.

By type, the precipitation subjected to our study is distributed as follows:

snow was observed . . . . . . . . 28 times
rain ” . . . . . . . . 4 ”
hoarfrost ” . . . . . . . . 1 ”
mixed precipitation . . . . . . . . 4 ”

Analyses were made:

in February . . . . . 17
” March . . . . . 13
” April . . . . . 5
” May (from 1 to 10) . . 2
Total . . 37

The distribution by months and by type of precipitation is seen from Table I:

Table I.

The intervals of time between the occurrence of precipitation during the period considered by us were extremely uneven. Whereas in February precipitation occurred almost daily, from April 11 to 29 the precipitation measured by the rain gauges of the meteorological station of the Institu-

...was not observed at all. The distribution of precipitation by days and the total amount of atmospheric water that fell and was measured with rain gauges at the Institute’s meteorological station are given in Table II.

Table II.

Notes to Table II. a) From April 15 to May 10, the wind data are not given, since, owing to the departure of A. V. Ignat’ev, observations of the wind were not made; b) wind observations for February and March refer to 1 o’clock in the afternoon; further, observations were made three times a day; for uniformity, we have also taken into account for April only the observations referring to 1 o’clock in the afternoon.

From this it is evident that the greatest average amount of meteoric water falling in one precipitation event was observed in April. In this same month there occurred the largest amount of water, which fell on April 1 in the amount of 87 mm.

If the winds are divided into 4 principal directions, then Table II shows that

for 10 days with wind from N to W there were 6 (60%) days with precipitation,
for 11 days with wind from W to S there were 8 (75%) days with precipitation,
for 45 days with wind from S to E there were 24 (55%) days with precipitation,
for 7 days with wind from E to N there was 1 (15%) day with precipitation.

Thus, during the fall of precipitation, southerly and southeasterly winds were observed predominantly, but precipitation occurred relatively more often with westerly and northerly winds.

Let us now compare the mean monthly velocities of the winds that accompanied precipitation with the mean monthly velocities from daily observations.

Table III.

From the data of Table III one may conclude that the mean wind velocity during the fall of precipitation is close to the overall mean velocity.

A comparison of wind velocities with the number of cases of precipitation and with the amount of water that fell in each case likewise does not make it possible to detect any regularities in this respect.

In all analyses, both nitrous and nitric acids were found, and the precipitation proved to be richest in ammonia.

The results of all analyses of precipitation collected in glass vessels on the tower of the physical building of the Institute are given in Table IV.

Table IV.

Table IV (continued).

From Table IV it is seen that the following maximum and minimum values were found for the nitrogen compounds studied in atmospheric precipitation (Table V):

Table V:

The average content of the studied compounds in the various kinds of precipitation is as follows.

Table VI.

If we discard the data for hoarfrost, since such an analysis was carried out only once and may, perhaps only accidentally, have given more significant quantities of the compounds studied, then we obtain the following average quantities of nitrogen compounds in atmospheric precipitation falling in the city of Tomsk:

It is of interest to compare the average quantities of ammonia and nitric acid found by us in local precipitation with the quantities of these compounds in precipitation in other places. Here, together with the data for the city of Tomsk, are some similar data borrowed by us from the article by A. Pozdnyakov.

Table VII.

The average quantities of ammonia for different kinds of precipitation are also given there; we place them in Table VIII together with the corresponding data for Tomsk.

Study of the Composition of Atmospheric Precipitation

Table VIII.

From this table it is evident that the absolute amount of $NH_3$ increases from rain to rime at all three points. In addition, it turned out that: a) the average ammonia content in snow in Tomsk is almost the same as in Ploty, and considerably greater than in Odessa; b) the average ammonia content in rain and in rime is almost the same in all three places.

The relation between the average amounts of ammonia and nitric acid for the various places, according to Table XI, is as follows:

for Montsouris it is equal to . . . 1 : 1.29
    “ Odessa . . . . . . . . . 1 : 0.84
    “ Tomsk . . . . . . . . . 1 : 0.44
    “ St. Ploty . . . . . . . . 1 : 0.20

The dependence of the average monthly amounts of the nitrogen compounds studied on the number of days with precipitation is difficult to derive, given the insignificance of our observations. According to Pozdnyakov, the content of nitrogenous compounds in precipitation is in inverse relation to the number of days with precipitation.

If the average monthly amounts of the compounds studied, derived in Table IV, are compared with the data of Table II, it may be noted that precipitation more abundant in moisture is distinguished by a smaller content of nitrogenous compounds.

To clarify the question of how the composition of a given precipitation changes as it falls, separate portions were taken at the beginning and at the end of the fall. Here are the results of such analyses:

Table IX.

The data of this table show that the composition of precipitation during its fall is not the same. It may be said that in all cases the amount of nitrogenous compounds decreases toward the end of the precipitation; the falling precipitation seems to wash them out of the air.

In order to clarify the question of the extent to which local conditions influence the content of the nitrogen compounds under investigation in atmospheric precipitation, we simultaneously collected them on the tower of the Institute and outside the city, far from dwellings and buildings. Unfortunately, we were able to do this in only four cases. The results of the analysis are placed in Table X.

Table X.

From consideration of Table X it is evident that the amounts of ammonia and nitrous acid in the precipitation collected on the tower of the Institute’s physics building are greater than in the precipitation from outside the city, whereas the amount of nitric acid proved, in one case, to be smaller.

The influence of the time of day and night and of the season on changes in the quantity of the nitrogenous compounds we studied is difficult to determine from the given number of observations.

The greatest influence on the composition of atmospheric precipitation is undoubtedly exerted by the direction and speed of the winds that accompanied its fall. In Table XI all cases of precipitation, with the exception of hoarfrost, are grouped according to wind direction, and the averages of all quantities of the compounds studied, found for each wind direction, are taken.

Table XI.

Table XI generally shows that the highest content of the investigated nitrogen compounds is observed with winds from the south and southwest (from S to WSW).

In Table XII the winds accompanying precipitation are distributed by velocities, and the average quantities of the investigated compounds in the precipitation corresponding to these velocities are given.

Table XII.

It is difficult to draw any definite conclusions from this table. For this, a larger number of observations is evidently necessary.

Finally, it must be mentioned that the passage of the tail of Halley’s comet near the Earth had no noticeable effect on the content of nitrogen compounds in atmospheric precipitation, as is shown by the analysis of the rain of May 7.

Conclusions.

1. Ammonia, nitrous acid, and nitric acid should be regarded as constant constituents of meteoric water falling in Tomsk.

2. In the precipitation investigated by us the following average quantities were obtained:

1. More abundant precipitation is characterized by a lower content of the nitrogen compounds studied.

2. The composition of precipitation during its fall is not uniform: toward the end of the fall, the amount of nitrogen compounds decreases.

3. Precipitation collected in the city is distinguished by a higher content of ammonia and nitrous acid and, apparently, a lower content of nitric acid than precipitation collected outside the city, far from dwellings and buildings.

4. The highest content of nitrogen compounds is observed with winds from S to WSW.

5. No influence of wind speed on changes in the content of nitrogen compounds was found.

Tomsk
May 10, 1911.

Plate for the article by A. Bykov and K. Karpov.

Front view.

Side view.

Section along A–B.

Longitudinal section.

A.

B.

Plan.

80 60 40 20 0 100 200 300 400 mm.

1. See Molinie, “Étude critique de dosages d’azote nitreux,” Annales de l’Observatoire de Montsouris, 1901. ↩

2. S. K., 101, p. 62. ↩