Assessment Of Air Quality In The Southwestern Part Of The Świętokrzyskie Mountains Based On Selected Indicators

Background: This article presents the results of research on the air quality which has been under the anthropogenic impact of the cement and lime industry in the Świętokrzyskie Mountains for many years. Research using geo- and bio-indicators was carried out at fixed measuring points in the years 2016-2018. Results: Hypogymnia physodes (L.) Nyl. and two-year old Scots pine needles Pinus silvestris L. were used for bioindication research. Physico-chemical properties of precipitation were developed on the basis of research conducted at the Jan Kochanowski University’s field research station located on the Malik. Increased pH and specific electrolytic conductivity (EC) of precipitation, as well as variable concentrations of heavy metals throughout a year were shown. Conslusions: Analysis of the chemical properties of transplanted lichens and pine needles confirmed the presence of elements from the cement and lime industry sector located in the Białe Zagłębie. Scanning electron microscope (SEM) image of the needles’ surface revealed morphological changes resulting from pollution of stoma opening and closing by small solid particles of anthropogenic origins, disturbing a gas exchange.

Hypogymnia physodes (L.) Nyl used in bioindication [34,35,36,37,38], and that is why, it was transplanted from the Borecka Primeval Forest (north-eastern Poland) where it occurs widely. The Borecka Primeval Forest belongs to the most valuable forest complexes in Europe due to the natural preservation of Central European deciduous forest habitats and the low anthropogenic impact characterised by a negligible share of heavy metal concentrations in atmospheric precipitation [39].
The Hypogymnia physodes (L.) Nyl lichens were taken on approx. 30-cm twigs and then placed in 22 control points at a height of approx. 2 m above ground level, using plastic self-locking bands. The duration of lichen exposure in the area of anthropogenic pressure lasted for six months in four measuring series, two for each half year (warm, cool). Each time, lichens (after the transplantation time) and pine needles (after the growing season) were transported to the Environmental Research Laboratory of the Jan Kochanowski University, where they were subjected to further tests. All samples were washed with deionised water three times. After having been dried at 65 0 C for 24 hours, the airdried samples were ground in an IKA A-11 Basic organic matter mill. In the ground samples, pH was analysed in solutions obtained by mixing the samples with water or a 1N KCl purum p.a. solution in a ratio of 1:2.5. After 24 hours, the pH value was measured using a HACH HQ-40d multiparameter with an INTELLICAL electrode. A mixture of nitric acid (V) (Suprapur Merck 65%) and hydrogen peroxide purum p.a. in a ratio of 2.5:1 was used for distributing wet samples of 0.1 g weighed amounts in polytetrafluoroethylene (PTFE) vessels. Material prepared in that way was subjected to microwave waves of 1400 W power and temperature of 200 o C for 40 minutes using the Multiwave 3000 Anton Paar mineraliser. The mineralised material and monthly collected samples of precipitation were subjected to chemical analysis for the content of selected metals (Al, Cd, Cr, Co, Cu, Fe, Ni, Pb, Zn), using the ICP-MS-TOF OptiMass 9500 mass spectrometer. Results consisted of an average value of three measurements. In order to control the quality of obtained results, such certified reference materials as ERM-CA713 made by the Institute for Reference Materials and Measurements in Belgium were used. The obtained data was statistically elaborated using the Statistica 13.1 program.
Meteorological and climate data for the Kielce weather station was obtained from the OGIMET portal.
The volume of emissions was elaborated basing on the data retrieved from the Regional Inspectorate of Environmental Protection in Kielce. Needle surface morphology was characterised by the method of scanning electron microscopy using a Hitachi TM3000 microscope (under full vacuum and with 15 kV accelerating voltage) at the Institute of Inorganic Chemistry and Technology at the Cracow University of Technology. The direction of air mass inflow was tested using the Hysplit model.

Results
The quality of atmospheric air in the Białe Zagłębie is primarily determined by the type of economy carried out in its area. The rock raw material mining and processing industry and, additionally,  Analysis of PM10 showed variable values throughout the year. Dust concentrations in the air correlate with the increase in cement and lime production (Fig. 4a). Increased values in winter periods could be related to the release of pollutants from domestic heating installations and the inflow of air from local and remote sources of industrial emissions [40], (Fig. 4b).
The hourly values of sulphur dioxide and nitrogen dioxide concentrations in the whole analysed period did not exceed the permissible values at both Provincial Inspectorate of Environmental Protection's measuring stations. In the case of sulphur dioxide and PM10, there was an increase in pollution during the cold half-year and a decrease during the warm half-year with lower concentration values.
The relationship between SO 2 and PM10 concentrations and air temperature was noticeable (Fig. 5).  Table 2.  (13) and Lipowica (21), located in the immediate vicinity of the cement plant [22]. The increased content of iron and aluminium in the air, apart from the emission from cement plants, was also associated with the weathering process of rocks and minerals [42]. The next largest element in the six-month series was zinc. Its values were the highest during the second series of transplantation, with an average of 41.7 mg.kg − 1 d.m. The highest concentrations were recorded in thalli exposed in Bolechowice (11) and Lipowica (21), and the lowest ones were found in Chorężów (7)  It was the largest for zinc -by 50%, lead and copper by 23%, aluminium by 17%, and iron and nickel by 10%. Only concentrations of cobalt, chromium and cadmium slightly decreased. During the second year of lichen transplantation, the concentrations of accumulated elements were higher in the samples exposed in the cold half-year in comparison with the elements accumulated in the warm halfyear for: copper (by 83%), cadmium (by 64%), lead (by 57%), cobalt (by 54%), and chromium (by 51%). A decrease in concentrations was noted for other heavy metals. It was the highest for aluminium (by 174%), zinc (by 97%), iron (by 50%), and nickel (by 9%).
There was a spatial pattern of concentrations of selected trace elements (Pb, Cu, Ni) observed in a latitudinal system, i.e. higher in the area of lime and cement plants within 2 km from the emission source, and lower east of them, located in the vicinity of forest complexes within more than 2 km from rock processing plants. A source of heavy metals in the vicinity of lime plants in Bukowa may be the co-combustion of car tires in a process of lime production. Particles deposited inside the intercellular structure of needle may penetrate it and thus cause its capping which disturbs a gas exchange [43,44,45]. SEM/EDS analysis of the chemical composition confirmed the presence of metals (Pb, Fe and Al) as well as Ca, K and Mg (Fig. 8). The most important elements included in the cement-lime dust comprise of Pb, Fe, Al, and Ca. It may therefore be concluded that the direct source of emissions of elements found on the surface of the needles were the cement and lime plants operating in the study area.
Using the PCA (principal component analysis) method, three main components were distinguished, i.e. PC1 -PC3 (Table 3). In total, they generated 64% of cumulative total variance of trace elements in the samples from the analysed area of the Białe Zagłębie, regardless of bio-indicator's location. They take into account the conditions associated with the cement and lime industry operating in this area (PC1-PC3) and transportation resulting from the course of the S7 express way at a distance of about 1 km from the study area (PC3).
The first component (PC1) generated 34% of total variance and showed high weight (≤ -0.87) for Fe and Pb (Table 3). The second component (PC2), in turn, formed 17% of total variance with the highest weight for Zn and Cr. Also important is the PC3 analysis (13% of variance) which indicated high weight for Cu (Fig. 9).

Discussion Of Results
As a result of local emissions, the chemical composition mainly showed the impact of dust pollution, confirmed by the presence of heavy metals, especially lead, chromium, nickel, and copper. The results of the chemical composition of precipitation on the Malik Mountain were similar to the concentrations of nickel, cadmium, cobalt, and chromium obtained on the basis of atmospheric precipitation in the region of Upper Silesia [46]. In all years of research, the average annual concentrations of iron and copper in the precipitation water from the Białe Zagłębie were several times higher than those obtained in the most industrialised and urbanised part of the Central Europe.
Much lower concentrations of the analysed metals were found in atmospheric precipitation studied in 2007-2008 in the Tibetan Highland at Nam Co [47]. In samples of the melted mountain glacier from Mount Everest [48] and in snow samples taken in the Himalayas [49] and the Pamir Mountains [50], lower concentrations of aluminium, chromium, iron, and cobalt were found than in the Świętokrzyskie Mountains. Only concentrations of lead, aluminum and cobalt in the urban part of Mersin in Turkey [51] were several times higher than in the south-western part of the Świętokrzyskie Mountains.
Research conducted in Singapore [52], Virginia [53], Nakanoto [54], and the Aegean Sea [55] showed similar concentrations of lead, cadmium and chromium to those found in the Świętokrzyskie Mountains. Monthly average copper concentrations on the Malik Mountain, only in the case of research in 2017, especially for February and March, were comparable with the results obtained in precipitation water in Singapore [52]. In other regions of the world, lower copper concentrations were recorded than in the Świętokrzyskie Mountains (the lowest ones in the Himalayas and Virginia).
Research using the same lichen species is carried out in many regions of the world. Due to their high accumulation capacity, they are widely used in areas exposed to high industrial pressure. In Poland, studies on the same species were carried out by Białońska and Dayan [56] [61] than in the study area. Studies conducted on the Kola Peninsula (Russia), in its industrialised part [62], showed comparable concentrations of chromium and zinc and much higher concentrations of lead (7.4 times), strontium (2 times), copper (8.6 times), nickel (63.4 times) and iron (3 times) than in the study area. In the northern part of Estonia, being exposed to alkalisation by the cement plant [63,17], concentrations of chromium, lead, iron, zinc and copper were found to be about half as high as in the study area, but it should be noted that the authors did research on one-year-old needles.
Studies conducted by Juranović-Cindrić et al. [64] confirm the physiological changes of needles by demonstrating the relationship between mineral deficiency in soils and advanced alkalisation. Studies carried out by Barga-Wiecławska et al. [21] in the Białe Zagłębie confirm the changes in the soil profile towards alkalisation resulting from more than forty-year-old emission of cement-lime dust.
The conducted principal component analysis indicated the conditions associated with the cement and lime industry operating in this area (PC1-PC3) and transportation resulting from the course of the S7 express way at a distance of about 1 km from the study area (PC3). The Kozłowski's research (2013) showed that the cement and lime dust emitted by the industry operating in this area is characterised by an increased content of Fe, Pb, Cr, Zn, and Cu resulting from the technological process used. For the production of clinker and lime, coal, coal dust, coke and car tires are commonly used.
The aim to assess the extent of the impact of air pollution sources on the environment is a difficult task, especially if there are many emitters located in a small area. Such a case is in the south-western part of the Świętokrzyskie Mountains, where several plants extracting rock raw materials and producing cement and lime have been located in close proximity to each other. This area already in the 1970's was classified as the area of the so-called ecological disaster.
Based on the conducted research, significant changes in the natural environment were found in the Białe Zagłębie. They mainly concern the air quality and atmospheric precipitation properties which in Relationship between SO2 and PM10 concentrations and air temperature (January 2018). Graphic image of relationships among PC1, PC2 and PC3 components