This work presents the results of five-year investigations (2010-2014) on the content of water-soluble fraction of heavy metals in atmospheric precipitation in Pribaikalye (Russia). The studies have been performed at the urban (Irkutsk) and rural (Listvyanka) sites within the EANET program (Monitoring of Acid Deposition in East Asia) since 2000. Precipitation was sampled during continuous monitoring. In warm period (May-October), atmospheric precipitation was collected by automatic “wet-only” samplers. In cold season, plastic containers were used for snow sampling. Maximal concentrations of the majority of elements were recorded at site Irkutsk, which is subject to higher anthropogenic impact. The exception was for Pb, Ni and Zn characterized by higher acidity, whose content was higher at the rural site. Maximal concentrations of the majority of elements were recorded in spring during the driest period of the year and minimal in summer with the annual maximal amount of precipitation. Correlation analysis revealed high coefficient of interconnection V and Mn with major acid-forming anions and . Maximal correlation coefficient (0.98) was recorded for Co and at site Listvyanka. There was no correlation between pH of atmospheric precipitation and concentrations of all heavy metals, except Pb. The results obtained show higher level of pollution of atmospheric precipitation by heavy metals at monitoring sites in Pribaikalye compared to some European countries.
Global emissions of heavy metals into atmosphere from the main anthropogenic sources have been reviewed in [
In Russia, data on emissions of heavy metals from the main sources are incomplete, as some enterprises control rather emissions of particulates than those of heavy metals. This is attributed to the fact that heavy metals concentrate on the surface of particulates emitted, and their decrease automatically reduces emission of heavy metals. In addition, the control of emission of particulates is less complicated and less laborious than the control of certain metals. In European countries, the composition of heavy metals in atmospheric precipitation and atmospheric aerosol is monitored continuously, annual reports on investigations at monitoring sites are published [
The study of chemical composition of atmospheric precipitation helps estimate the level of atmosphere pollution. Precipitation is an integral indicator of airborne pollution as they capture and wash out the majority of impurities, including heavy metals, from the atmosphere. Many of them are highly toxic [
The aims of this work were to estimate quantitatively the content of heavy metals in atmospheric precipitation at monitoring sites in Pribaikalye, to study the mechanisms of them within year distribution and to reveal correlation between heavy metals and major anions.
Chemical composition of atmospheric precipitation was studied at monitoring sites-Irkutsk (52.3˚N, 104.4˚E) and Listvyanka (51.9˚N, 104.7˚E). Site Irkutsk is the largest industrial center in the south of East Siberia with the population of about 600,000 people. Site Listvyanka is a rural site located 70 km away from Irkutsk on the north-western coast of the southern basin of Lake Baikal. In recent years, the settlement of Listvyanka (5000 people) has become a tourist center at Lake Baikal, thus causing an increase of road transport on the relatively small isolated territory. In 2000, these sites were included in the International Program “Monitoring of Acid Deposition in East Asia (EANET)”. Sampling and analyses of samples of atmospheric precipitation were performed according to recommended methods for the entire network of sites of this program [
In 2010-2014, approximately 600 samples of atmospheric precipitation were analyzed for heavy metals, major anions and pH. Samples of rain and snow water were filtered through membrane filters of 0.45 µm. Concentrations of heavy metals were measured in the dissolved fraction using inductively coupled plasma mass spectrometry on a spectrometer “Agilent-7500ce”. Anions were studied using high-performance liquid chromatography on a chromatograph “Milichrom A-02”. The measurement accuracy of concentrations of heavy metals and major anions were regularly controlled by annual inter-laboratory calibrations within the framework of international programs NIVA [
As is known, chemical composition of atmospheric precipitation is regulated by meteorological, climatic, seasonal and other factors affected by both natural processes and human activity.
Humid air masses penetrate deep into the continent from the Atlantic. Regeneration of cyclones above large industrial regions can be one of the circulation mechanisms of this effect, due to which they stay longer and are transported to East Siberia more intensely [
Average annual concentrations of heavy metals measured in atmospheric precipitation at monitoring sites (Irkutsk and Listvyanka) in Pribaikalye were compared with those obtained at three EMEP monitoring sites [
Hence, the content of heavy metals at monitoring sites of Europe and Pribaikalye can be compared only in case when atmospheric precipitation forms under
Monitoring site | Amount of precipitation, mm | Element | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
V | Cr | Mn | Fe | Co | Ni | Cu | Zn | Cd | As | Pb | ||
Germany (Zingst) | 771 | 0.38 | 0.13 | 2.34 | 14 | 0.02 | 0.29 | 2.13 | 7 | 0.03 | 0.08 | 0.81 |
Finland (Hailuoto) | 452 | 0.43 | 0.16 | 2.03 | 25 | 0.04 | 0.17 | 1.93 | 3 | 0.03 | 0.04 | 0.66 |
Sweden (Arup) | 1049 | 0.64 | 0.13 | 4.07 | - | 0.02 | 0.28 | 0.79 | 8 | 0.03 | 0.14 | 0.47 |
Russia (Irkutsk) | 480 | 1.33 | 0.84 | 20.6 | 39 | 0.38 | 1.54 | 4.55 | 23.3 | 0.26 | 0.14 | 0.52 |
Russia (Listvyanka) | 430 | 0.76 | 0.66 | 11.5 | 30 | 0.29 | 1.81 | 3.66 | 29.4 | 0.22 | 0.09 | 1.01 |
the influence of natural factors. However, we observe rather high concentrations of heavy metals at site Listvyanka and even higher at site Irkutsk, which is likely caused by the impact of other factors on chemical composition of precipitation, including anthropogenic ones.
The main source of atmosphere pollution in Pribaikalye is Irkutsk-Che- remkhovo industrial complex, which includes enterprises of heat and power engineering, nonferrous metallurgy, chemical, pulp-and-paper industry, construction materials, road and railway transport and others. Because of prevailing north-western transport of air masses in this region, impurities emitted into atmosphere are transported from cities and towns, including Irkutsk, along the Angara River valley towards the coast and water area of Southern Baikal, where site Listvyanka is located. Another source of atmosphere pollution in Pribaikalye may be transport of air pollutants from the neighboring industrial region (Krasnoyarsk Krai) [
As was mentioned earlier, one of the main sources of emission of heavy metals into atmosphere is heat and power engineering. According to the EMEP report, the content of heavy metals in atmospheric precipitation significantly decreased from 1990 to 2011: lead by 90% and cadmium by 60% due to the complete substitution of coal by natural gas at the enterprises of heat and power engineering [
As is seen from these figures, no pronounced maximum of heavy metals was registered in winter period. During December-February, metals are emitted into atmosphere mainly with particulates. Therefore, they are in insoluble state. The exceptions are such elements as V and Co, whose concentrations are, on the contrary, maximal in winter. According to the data of National Atmospheric
Emission Inventory, motor fuel, mainly diesel, is 98% source of V emission [
Maximal concentrations of the majority of metals were recorded in spring, as a rule, in dry period, which was attributed primarily to natural factors. In spring, the concentrations of aerosol of terrigenous origin increased after snow melting and with the rise of air temperature and increase of wind velocity in atmosphere of Pribaikalye. Forest fires, a powerful source of aerosol in the Siberian region, usually happen in this period.
Hence, despite significant variations of average monthly concentrations of heavy metals there was a trend in the within-year dynamics with spring maximum and summer-fall minimum for the majority of elements. Minimal content of heavy metals in atmospheric precipitation in summer-fall was attributed to purification of atmosphere from impurities due to high amount of precipitation (up to 70% of annual total), which is consistent with within-year dynamics of ionic composition of atmospheric precipitation. According to Netsvetaeva et al. 2013 [
Long-term investigations showed that average annual concentrations of Pb, Ni and Zn in atmospheric precipitation at site Listvyanka were higher than at site Irkutsk despite high anthropogenic load on the industrial center (see
Similar dynamics was observed for Ni at site Listvyanka where its content was higher than in Irkutsk because of spring maximum (
As it is seen from
A minimal value for Со is revealed in September, and maximal one-in April for Irkutsk site. At Listvyanka site, minimal value is observed in October, and maximal one-in February. Ni content is maximal in April and minimal in October at both sites. Ascontent for Irkutsk site is maximal in April, and for Listvyanka site-in November. The only element which has maximal values during summer period is Cd, its content is maximal in July at both monitoring sites. This is probably due to cyclones from Mongolia passing at that time over the region. Pb content is maximal in November at Irkutsk site and in December at Listvyanka site.
Such elements as Fe, Mn, Cu, Zn have maximal values in April except Fe, its maximum for Irkutsk site takes place in January. For Listvyanka site, maximal content of Mn is in February, one of Fe is in December, and one of Cu and Zn is in April, like for Irkutsk site (
Correlation coefficients were calculated for establishing interconnection between concentrations of major anions and pH and heavy metals in atmospheric precipitation (
In Listvyanka, the majority of atmospheric precipitations were acidified to a certain degree. It was supposed that there would be good correlation between concentrations of heavy metals and pH value. However, the calculations showed opposite correlation. At site Listvyanka, the highest correlation coefficient was recorded only for lead (0.56).
Component | V | Cr | Mn | Fe | Co | Ni | Cu | Zn | As | Cd | Pb |
---|---|---|---|---|---|---|---|---|---|---|---|
0.68 | 0.08 | 0.43 | 0.25 | 0.20 | 0.20 | 0.42 | 0.07 | 0.47 | −0.06 | 0.09 | |
0.52 | 0.35 | 0.69 | 0.39 | 0.41 | 0.28 | 0.51 | 0.26 | 0.46 | 0.10 | −0.06 | |
0.59 | 0.14 | 0.52 | 0.23 | 0.57 | 0.40 | 0.20 | 0.10 | 0.18 | 0.30 | −0.33 | |
0.65 | 0.08 | 0.58 | 0.30 | 0.15 | 0.11 | 0.55 | 0.06 | 0.54 | 0 | 0.21 | |
рН | −0.45 | −0.11 | −0.27 | −0.12 | −0.39 | −0.34 | −0.09 | −0.13 | −0.19 | −0.17 | 0.70 |
Component | V | Cr | Mn | Fe | Co | Ni | Cu | Zn | As | Cd | Pb |
---|---|---|---|---|---|---|---|---|---|---|---|
0.62 | −0.02 | 0.81 | 0.86 | 0.63 | 0.46 | 0.47 | −0.15 | 0.66 | 0.72 | 0.49 | |
0.83 | 0.14 | 0.57 | 0.67 | 0.98 | 0.23 | 0.17 | −0.11 | 0.25 | 0.50 | 0.13 | |
0.48 | 0.25 | 0.68 | 0.68 | 0.45 | 0.26 | 0.38 | −0.04 | 0.74 | 0.50 | 0.27 | |
рН | −0.30 | −0.18 | −0.11 | −0.08 | −0.39 | −0.01 | 0.26 | −0.29 | −0.21 | −0.19 | 0.56 |
In recent years, the rise of acidity of atmospheric precipitation has been registered in Pribaikalye [
At site Listvyanka, correlation coefficients were higher. Anions correlated with a higher number of elements (
Thus, the investigations performed confirm that in the regions of Pribaikalye remote from industrial centers, solubility of heavy metals increased because of acidification of atmospheric precipitation. High concentrations of heavy metals in atmospheric precipitation can negatively affect the natural environment causing inhibition of forests, increase of areas of necrosis of needles and leaves and decrease of their mass [
In 2010-2014, investigations of the content of heavy metals in atmospheric precipitation, their emission into atmosphere and seasonal dynamics were performed at two monitoring sites in Pribaikalye. The main sources of emission of heavy metals into atmosphere are eolian transport from the underlying surface, enterprises of heat and power engineering, forest fires and road transport. Maximal concentrations of the majority of elements were recorded in spring in a drier period of the year, whereas minimal content was registered in summer, when the amount of precipitation in this region was maximal.
The results obtained show higher level of pollution of atmospheric precipitation by heavy metals at monitoring sites in Pribaikalye compared to some European countries. High correlation was established V and Mn with major acid-forming anions
The work was supported by the program 0345-2016-0008 “Assessment and Forecast of Ecological State of Lake Baikal and Adjacent Territories under Conditions of Anthropogenic Impact and Climate Changes”.
Onishchuk, N., Khodzher, T. and Netsvetaeva, O. (2017) Chemical Composition of Atmospheric Pre- cipitation at Monitoring Sites in Pribaikalye (East Siberia, Russia). American Journal of Climate Change, 6, 374-384. https://doi.org/10.4236/ajcc.2017.62019