Impact of Technogenic Saline Soils on Some Chemical Properties and on the Activity of Selected Enzymes

: The study was based on saline soils with surface mineral layers impacted by the waste produced by the soda plant in Poland. The activity of selected enzymes (catalase CAT, alkaline AlP, and acid phosphatase AcP), pH in KCl, content of the clay, total organic carbon (TOC), total nitrogen (TN), total exchangeable bases (TEB), electrical conductivity (EC e ), CaCO 3 , and concentration of available phosphorus AP were investigated in the soil next to the soda plant. Based on the enzyme activity, the following were calculated: enzymatic pH indicator AlP/AcP , the resistance index ( RS ), resilience index ( RL ), relative changes ( RCh ), and the time index ( TI ). The soil was sampled from the mineral horizon in spring and autumn from eight (S1–S8) soil sampling sites in the area of the soda plant and from the control point (C). Soil is characterized by alkaline reaction. Statistical analysis (ANOVA, η 2 effect size) showed signiﬁcant variation in parameters under the inﬂuence of different sites next to soda plant. The content of TOC ranged from 4.70 to 47.7 g kg − 1 , and TN from 19 to 4.36 g kg − 1 . EC e next to the soda plant ranged between 6.87 and 204 mS cm − 1 . The highest values were conﬁrmed in the soil of S1 both in spring and autumn. Higher TEB values were noted in the soil in autumn. In the soil within the impact of the soda plant, the AP content decreased and in the soil from sites S1, S3, S6, and S8 (in spring), the lowest AP content was recorded at 1.20, 4.14, 5.98, and 0.99 mg kg − 1 , respectively. The highest activity of AlP in spring was noted at site S1 and in autumn at site S4. In the soil next to the soda plant, the activity of AcP decreased, as compared to the control which is seen from the negative values of the coefﬁcient of relative changes ( RCh ). The analysis of RCh in the catalase activities showed that in the soil from sites S1, S2, S3, S4, and S5, the activity increased, as compared to the control. The lowest values of the resistance index ( RS ) for phosphatases were reported in the soil of S6. Research shows that the activity of enzymes and their indexes make it possible to conduct long-term monitoring and identify the processes in soil. J.L., J.L., K.G. A.S.-Z.; J.L.; visualization, J.L.; writing—original draft, J.L. and K.G.; writing—review and J.L. A.S.-Z. read of


Introduction
Soil salinity is one of the major causes of environmental degradation and human health deterioration [1]. High salinity has negative effects on soil fertility. Salinated soils are formed by salts that are more easily soluble in cold water as compared to gypsum. They include saline soils (solonchak), sodium soils (solonetz), and saline-sodium soils [2]. Soil salinization occurs due to a high salt content, high Na + accumulation, and high pH, often due to high CO 3 2− content in soil [3]. Sodium accumulates in the sorption complex, affects the state of the soil dispersion, and affects its capacity for swelling increases while the soil water permeability decreases. As for an excessive salinity, the soil solution contains too many, as compared to the plants requirements, with such cations as: Mg 2+ , Ca 2+ , K + , Na + , and anions: NO 3 − , SO 3 2− , and Cl − , (COO) 2 2− [4]. According to Rengasamy [5,6], soil salinisation covers 932.2 Mha globally (representing about 7% of earth's continental extent), with 38.4% in Australasia, 33.9% in Asia, 15.8% phosphorus concentration in soils in the territories adjacent to the soda plant. The aim of the study was also to assess whether in changed soil conditions, the enzymatic activities retain typical relationships with selected physical and chemical soil properties.

Study Area and Soil Samples
The research was carried out in the Notec River valley in the area adjacent to the CIECH Soda Polska S.A. (the soda plant founded in 1882) in Inowrocław. The city is located on the Inowrocław Plain in the Kujawsko-Pomorskie province (52 • 40 N; 18 • 16 E) (Central Poland), with dominant Mollic Gleysols and Gleyic Phaeozems (in Poland, known as black earths). The soils degraded by the technogenically induced salinization process in Inowrocław-Matwy can be classified as Mollic Technosols (Calcaric) [8]. In that area, the climate demonstrates to be cold and temperate. Inowrocław is a town with considerable precipitation. Even during the driest months, precipitation is high. The climate in that area has been classified as Dfb-compliant with the Köppen-Geiger system. The year-average temperature is 7.9 • C (from −3.2 • C to 18.1 • C) ( Figure 1) and the year-average precipitation is 44.25 mm ( Figure 2) (from 23 mm to 77 mm). The mean temperature of 18.1 • C makes July the hottest month of the year. Precipitation is lowest in February with an average precipitation of 23 mm and it mostly occurs in July (on average, 77 mm).
Energies 2021, 14, x FOR PEER REVIEW 3 of 1 activity of some enzymes. Our objective was to study the alkaline, acid phosphatase, an catalase activity, in addition to the total organic carbon, total nitrogen, and available pho phorus concentration in soils in the territories adjacent to the soda plant. The aim of th study was also to assess whether in changed soil conditions, the enzymatic activities retai typical relationships with selected physical and chemical soil properties.

Study Area and Soil Samples
The research was carried out in the Notec River valley in the area adjacent to th CIECH Soda Polska S.A. (the soda plant founded in 1882) in Inowrocław. The city is lo cated on the Inowrocław Plain in the Kujawsko-Pomorskie province (52°40′ N; 18°16′ E (Central Poland), with dominant Mollic Gleysols and Gleyic Phaeozems (in Poland known as black earths). The soils degraded by the technogenically induced salinizatio process in Inowrocław-Matwy can be classified as Mollic Technosols (Calcaric) [8]. In tha area, the climate demonstrates to be cold and temperate. Inowrocław is a town with con siderable precipitation. Even during the driest months, precipitation is high. The climat in that area has been classified as Dfb-compliant with the Köppen-Geiger system. Th year-average temperature is 7.9 °C (from −3.2 °C to 18.1 °C) ( Figure 1) and the year-ave age precipitation is 44.25 mm ( Figure 2) (from 23 mm to 77 mm). The mean temperatur of 18.1 °C makes July the hottest month of the year. Precipitation is lowest in Februar with an average precipitation of 23 mm and it mostly occurs in July (on average, 77 mm  In the city center, the Cechsztyn salt dome (109 m a.s.l.) accumulates salt [23]. CIECH Soda Polska S.A. produces, e.g., precipitated calcium carbonate, light and heavy soda ash and sodium bicarbonate, as well as silica gels, zeolites and molecular sieves, hopcalit and fertilizer chalk. The plant satisfies 98% of the Polish demand for sodium carbonat exporting a considerable part of the production. The Solvay method uses very hig amounts of water and as a result, high amounts of wastewater are discharged through th pipeline into the Vistula River [23]. The waste used to be stored in the so-called sedimen tation tanks without appropriate safety measures, which resulted in the percolation of sa Energies 2021, 14, x FOR PEER REVIEW 3 of 1 activity of some enzymes. Our objective was to study the alkaline, acid phosphatase, an catalase activity, in addition to the total organic carbon, total nitrogen, and available phos phorus concentration in soils in the territories adjacent to the soda plant. The aim of th study was also to assess whether in changed soil conditions, the enzymatic activities retai typical relationships with selected physical and chemical soil properties.

Study Area and Soil Samples
The research was carried out in the Notec River valley in the area adjacent to th CIECH Soda Polska S.A. (the soda plant founded in 1882) in Inowrocław. The city is lo cated on the Inowrocław Plain in the Kujawsko-Pomorskie province (52°40′ N; 18°16′ E (Central Poland), with dominant Mollic Gleysols and Gleyic Phaeozems (in Poland known as black earths). The soils degraded by the technogenically induced salinizatio process in Inowrocław-Matwy can be classified as Mollic Technosols (Calcaric) [8]. In tha area, the climate demonstrates to be cold and temperate. Inowrocław is a town with con siderable precipitation. Even during the driest months, precipitation is high. The climat in that area has been classified as Dfb-compliant with the Köppen-Geiger system. Th year-average temperature is 7.9 °C (from −3.2 °C to 18.1 °C) ( Figure 1) and the year-aver age precipitation is 44.25 mm ( Figure 2) (from 23 mm to 77 mm). The mean temperatur of 18.1 °C makes July the hottest month of the year. Precipitation is lowest in Februar with an average precipitation of 23 mm and it mostly occurs in July (on average, 77 mm  In the city center, the Cechsztyn salt dome (109 m a.s.l.) accumulates salt [23]. CIECH Soda Polska S.A. produces, e.g., precipitated calcium carbonate, light and heavy soda ash and sodium bicarbonate, as well as silica gels, zeolites and molecular sieves, hopcalite and fertilizer chalk. The plant satisfies 98% of the Polish demand for sodium carbonate exporting a considerable part of the production. The Solvay method uses very hig amounts of water and as a result, high amounts of wastewater are discharged through th pipeline into the Vistula River [23]. The waste used to be stored in the so-called sedimen tation tanks without appropriate safety measures, which resulted in the percolation of sal  I  II  III  IV  V  VI VII VIII IX  X  XI XII   0   20   40   60   80   100   I  II  III  IV  V  VI  VII VIII IX  X  In the city center, the Cechsztyn salt dome (109 m a.s.l.) accumulates salt [23]. CIECH Soda Polska S.A. produces, e.g., precipitated calcium carbonate, light and heavy soda ash, and sodium bicarbonate, as well as silica gels, zeolites and molecular sieves, hopcalite, and fertilizer chalk. The plant satisfies 98% of the Polish demand for sodium carbonate, exporting a considerable part of the production. The Solvay method uses very high amounts of water and as a result, high amounts of wastewater are discharged through the pipeline into the Vistula River [23]. The waste used to be stored in the so-called sedimentation tanks without appropriate safety measures, which resulted in the percolation of salt to ground waters and thus in the salinity of fertile soils in the neighboring areas. The cause of soil salinity is also the emission of limestone dust and wind spreading around the waste from the surface of sedimentation tanks [24]. Ciech Soda Polska plants focus on green solutions. Such investments in Mątwy included, e.g., a post-production sludge dewatering system used for producing lime fertilizer, a flue-gas desulphurization system, barrier drainages at landfill sites protecting the land against flooding and salinization, and the insulation of waste ponds. About 90% of waste has been used for economic purposes (e.g., for the production of cement and lime fertilizer) and used-out waste ponds have undergone reclamation. Despite such actions, soil salinity remains at a relatively constant level. Some waste ponds were insulated with a foil screen, while others are found immediately on permeable land without any security measures. The construction of sedimentation tanks increased an undisturbed water table of ground waters, which has an unfavorable effect on soil properties (pH, ECe, the content of SOM and macronutrients, and sorption properties) [23]. According to Hulisz et al. [13], another factor affecting the soil salinity at the vicinity of Inowrocław is the breakdown of pipelines discharging wastewater and brine.
The soil was sampled from the mineral horizon (0-20 cm deep) in spring (April) and autumn (October) 2016 from eight sites in the area of the soda plant and from the control point ( Figure 3).

FOR PEER REVIEW 4 of 17
to ground waters and thus in the salinity of fertile soils in the neighboring areas. The cause of soil salinity is also the emission of limestone dust and wind spreading around the waste from the surface of sedimentation tanks [24]. Ciech Soda Polska plants focus on green solutions. Such investments in Mątwy included, e.g., a post-production sludge dewatering system used for producing lime fertilizer, a flue-gas desulphurization system, barrier drainages at landfill sites protecting the land against flooding and salinization, and the insulation of waste ponds. About 90% of waste has been used for economic purposes (e.g., for the production of cement and lime fertilizer) and used-out waste ponds have undergone reclamation. Despite such actions, soil salinity remains at a relatively constant level. Some waste ponds were insulated with a foil screen, while others are found immediately on permeable land without any security measures. The construction of sedimentation tanks increased an undisturbed water table of ground waters, which has an unfavorable effect on soil properties (pH, ECe, the content of SOM and macronutrients, and sorption properties) [23]. According to Hulisz et al. [13], another factor affecting the soil salinity at the vicinity of Inowrocław is the breakdown of pipelines discharging wastewater and brine.
The soil was sampled from the mineral horizon (0-20 cm deep) in spring (April) and autumn (October) 2016 from eight sites in the area of the soda plant and from the control point ( Figure 3). The sites differed in their method of use, as follows. Site S1: up to year 2000 places flooded with post-soda sludge to be reclaimed with secondary succession (a natural process leading to the recovery of primary qualities of the natural environment); site S2: flooded with post-soda sludge and with a deficiency of natural succession; site S3: the places around the clarifying-cooling "pond", in which carbonates get precipitated as waste; sites S4 and S5: where technical (the relief was transformed; it was covered with a layer of fresh soil and drainage was performed) and agrotechnical (for the fastest turfing possible of the sedimentation tanks with a mixture of grasses and the Fabaceae including Italian ryegrass, orchard grass, red fescue, red clover, and white clover) reclamation was completed; site S6: at the dried pond for ash waters; site S7: an agricultural field in which spring barley (Hordeum vulgare L.) was grown 500 m away from the soda plant; site S8: the Figure 3. Location of the study area. S1: up to year 2000 places flooded with post-soda sludge to be reclaimed with secondary succession; S2: flooded with post-soda sludge and with a deficiency of natural succession; S3: the places around the clarifying-cooling "pond", in which carbonates get precipitated as waste; S4 and S5: where technical and agrotechnical reclamation was completed; S6: at the dried pond for ash waters; S7: an agricultural field in the distance of 500 m from the soda factory; S8: the places in the vicinity of the city waste dumping sites, sewage treatment plant, and soda plant (with numerous communities of halophytes, mainly with Salicornia europaea); and C: the control site.
The sites differed in their method of use, as follows. Site S1: up to year 2000 places flooded with post-soda sludge to be reclaimed with secondary succession (a natural process leading to the recovery of primary qualities of the natural environment); site S2: flooded with post-soda sludge and with a deficiency of natural succession; site S3: the places around the clarifying-cooling "pond", in which carbonates get precipitated as waste; sites S4 and S5: where technical (the relief was transformed; it was covered with a layer of fresh soil and drainage was performed) and agrotechnical (for the fastest turfing possible of the sedimentation tanks with a mixture of grasses and the Fabaceae including Italian ryegrass, orchard grass, red fescue, red clover, and white clover) reclamation was completed; site S6: at the dried pond for ash waters; site S7: an agricultural field in which spring barley (Hordeum vulgare L.) was grown 500 m away from the soda plant; site S8: the places in the vicinity of the waste dumping sites, sewage treatment plant, and soda plant (with numerous communities of halophytes, mainly with Salicornia europaea); and site C: the control site. Soil control is defined as very fertile uncultivated soils (Mollic Gleysols) away from the soda plant impact site In each test area, 12 individual samples were taken using a random sampling design. The core samples were mixed to get the weight of about 1 kg of a representative sample for each site [25].

Chemical and Biochemical Analysis of Soil Samples
In the air-dried soil samples, sieved through ø 2 mm, some physical and chemical properties were determined: the content of the clay was assayed with the laser diffraction method applying the Masterssizer MS 2000 analyzer; pH in 1M KCl was measured potentiometrically [26]; total organic carbon (TOC) was assayed with the analyzer Vario Max CN, provided by Elementar (Germany); total nitrogen (TN) using the Kjeldahl method with the Kjeltec analyzer; total exchangeable bases (TEB) with the Kappen method [27]; and the electrical conductivity (EC e ) in the soil paste. CaCO 3 content was measured with the Scheibler's volumetric method. The content of available phosphorus (AP) was determined with the Egner-Riehm DL method [28].
The activity of the enzymes was assayed in fresh, moist, and sieved soil. The activity of the redox enzyme, namely catalase (CAT) [E.C. 1.11.1.6], in the soil with the Johnson and Temple method [29] was measured by applying the manganometric titration of the surplus of H 2 O 2 under acidic conditions.
The analyses of the enzyme representing the class of hydrolases, namely alkaline phosphatase [E.C. 3.1.3.1] (AlP) and acid phosphatase [E.C. 3.1.3.2] (AcP), were performed with 1 g of soil samples with the Tabatabai and Bremner method [30]. It is based on the colorimetric assaying of the released substrate p-nitrophenylphosphate (pNP) after the incubation of soil with MUB (modified universal buffer) at pH 11.0 for alkaline phosphatase and at pH 6.5 for acid phosphatase samples for 1 h at the temperature of 37 • C.
With the values of the activity of alkaline and acid phosphatase reported, the enzymatic index of the soil was calculated [31]: The resistance index (RS) and resilience index (RL) determined according to the activity of enzymes in the soil was calculated using the formulas proposed by Orwin and Wardle [32]: where D 0 = C 0 − P 0 , C 0 is the parameter value in the control, and P 0 is the parameter value in the disturbed soil.
where D 0 is the difference between the control (C 0 ) and the disturbed soil (P 0 ) in the soil sampled in spring, and D x represents a difference between the control and the disturbed soil with regard to time (soil sampled in autumn). The value of the resistance and resilience index is bounded by −1 and +1.
The mean values of the enzyme activities were also used to calculate the relative changes (RCh) according to the formula defined by Chaer and others [33]: where T is the mean enzymatic activity in the soil next to the soda plant and C is the mean value obtained for the control. Based on the results, the time index (TI) [34] was calculated: where t1 is the content of the element in spring and t2 is the content of the element in autumn. TI > 1 represents an increase, while TI < 1 represents a decrease in the content of some elements and the activity of the enzymes studied.

Statistical Analysis
An ANOVA test was performed with the results and analyses were conducted using Statistica 12 for Windows. One-way analysis of variance (ANOVA) was conducted to determine the effect of different sites on soil physical and chemical properties (clay, pH in 1 M KCl, CaCO 3 , TOC, and NT). A two-way analysis of variance was conducted to examine the main effect of different sites and the months of study on the enzymatic activities and the content of phosphorus. The relations between the CAT, AlP, and AcP activity, and the physical and chemical parameters were estimated with a correlation analysis based on Pearson's correlation coefficients (p < 0.05). The percentage share of the observable variability was calculated using the η 2 indicator with the ANOVA variance analysis method.
Multivariate characterization (PCA: principal component analysis) was applied using data for soil CAT, AlP, and AcP activities, in addition to the clay, pH, EC e , TEB, content of CaCO3, TOC, TN, and AP to analyze the relationships between the variables observed. The first three principal components (PC1, PC2, and PC3) were selected for a further interpretation of the results. Hierarchical cluster analysis (CA) with Ward's method [35] was used to identify the sampling similarity groups.

Physicochemical Properties
The accumulation of clay fraction ranged from 4.22 to 14.8%. Soils are characterized by the alkaline reaction (pH in 1 M KCl 7.7-7.9 at the sites of influence of the emitter and 7.1 in the control). There was a significant variation found in the content of CaCO 3 (from 3.88% to 48.3%) and 1.85% in the control soil (Table 1). C, N, and P are the three macroelements that are necessary for plant growth and soil quality. The content of TOC ranged from 4.70 to 47.7 g kg −1 (control 22.0 g kg −1 ) ( Table 1). The concentration of TOC varied significantly depending on the soil sampling site. The highest concentration of TOC was at S6 (at the dried pond for ash waters). However, no significant differences in the content of TOC at S1, S2, and S5 were identified. According to Peinemann et al. [36] and Wong et al. [37], salinity adversely affects the content of organic carbon in salt-affected areas by increasing the dispersion of aggregates, which intensifies SOC mineralization, and by increasing bulk density, which restricts access to the substrate for mineralization. Saline soils contain carbonates that complicate the C dynamics and are also subjected to increased losses of SOM due to dispersion and leaching.
The content of total nitrogen varied across the sites. The highest TN was observed in the soil of S8 (4.36 g kg −1 ), followed by S5 (3.29 g kg −1 ). As compared to the control, it was 120% and 67% higher than the control (C-1.96 g kg −1 ). The agricultural field (S7) showed a low TN value (1.77 g kg −1 ) ( Table 1).
The value of TOC/NT ranged from 2.5 to 58.1 (control 1.1) ( Table 1). The differences of TOC/NT (Table 1) demonstrate a varied rate of mineralization of organic C and N compounds. The narrow ratio of TOC/NT in the soils (S1, S2, S3, S4, S5, S7, S8, and C) indicates a very fast decomposition of organic matter by soil microorganisms, that nitrogen is more intensively mineralized, and that high amounts of N-NH + 4 are not used by the plants and gets accumulated in the ground. In the soil of S6, the value above 20 was recorded. Then, nitrogen immobilization occured. According to Lu and others [38], this might be due to the higher cation contents in the S6 soil as confirmed by Dąbkowska-Naskręt and Bartkowiak [39].
The value EC e next to the soda plant ranged from 6.87 to 204 mS cm −1 (control 4.11-5.97 mS cm −1 ) ( Table 2). Earlier research of those soils [40] showed that EC e was increasing with depth. The highest EC e value was found at a depth of 40-60 cm. The values varied significantly depending on the soil sampling site. The value EC e S7 (agricultural field) was 66.35 mS cm −1 . The estimates show that by 2050, salinity will have affected 50% of all the global arable land [41]. Most crops are sensitive to salinity [1]. Crops grown in saline soils suffer due to the high osmotic stress and disturbed nutrients' uptake, which decreases yields. According to Munns and Tester [42], soils are saline when EC e is 4 dS m −1 or more (131), which is approximately 40 mM NaCl. The highest values (p < 0.05) were found in the soil of S1 (up to 2000 places flooded with post-soda sludge), both in spring and autumn. The value EC e in the soil was changing throughout the season. A significantly higher EC e value was recorded in spring compared to autumn. Changes in rainfall and evaporation are key factors in the content of salts in soil layers. During spring, there is less rain (April) than in autumn (October) in Inowrocław (Table 1); thus, previously available moisture evaporated, leaving the salts on the soil surface. This increases the value of EC e . Heavy rainfall can change the soil salinity (EC e ) and macro and micronutrient status of the soil due to leaching. Total exchangeable bases (TEB) in the soil were significantly modified by the soil sampling site (in spring) ( Table 2). While higher TEB values were noted in the soil in autumn, there were no significant differences found in the TEB in the soils sampled from S1, S6, and S8.
The content of AP in the soil ranged from 0.99 to 44.65 mg kg −1 (in spring) ( Figure 4). In autumn, the content was significantly higher (p < 0.05) and ranged from 3.92 to 49.5 mg kg −1 . The content of available phosphorus varied significantly depending on the soil sampling site. The highest accumulation was recorded for the control. In the soil within the influence of the soda plant, the AP decreased, and in the soil from the S1, S3, S6, and S8 sites (only in spring), the lowest AP content was recorded. The AP concentration was significantly negatively related to pH in KCl (r = −0.652, p = 0.0033) and EC e (r = −0.481, p = 0.0430). However, the two parameters only in 42.5% and 23.1% determined the variation in AP in the soil. The results of the investigations by Dąbkowska-Naskręt and Bartkowiak [39] in the soil near the soda plant showed that with the cations affecting salinity measured with EC e were calcium and, to a lesser extent, sodium. According to Fageria et al. [43], phosphate availability in saline soils is highly controlled by both sorption processes and the low solubility of Ca-P minerals. However, Artamonova, et al. [44] stated that in the case of salinization, the degree of Ca 2+ saturation of the soil is reduced due to its replacement with Na + and Mg 2+ . The toxic effect of Na + increases in the presence of Cl − , sharply reducing the absorption of N, P, and K. The regression equation shows that with an increase in pH in KCl by 1 unit, the content of P decreased, lined by 45.83 mg kg −1 . According to Bano and Fatima [45], soil salinity and pH > 7.5 significantly reduces the plant P uptake as phosphate ions precipitate with Ca ions. However Pan et al. [46], Mahmood et al. [47], and Lemanowicz and Bartkowiak [20] reported that most saline soils are adequately supplied with P as the content of sodium ions may result in more soluble Na 3 PO 4 being formed. In the soil from S7 (arable field), the content of AP was 24.2 mg kg −1 (spring) and 39.7 mg kg −1 (autumn), which classifies the soil as part of the IV (low) class of concentrations in P [48]. The soil showed higher AP contents in autumn as compared to spring. According to Lu et al. [38], the differences in seasonal nutrient changes across different sampling areas could have been due to the differences in plant uptake, soil properties, and hydrological conditions. Total exchangeable bases (TEB) in the soil were significantly modified by the sampling site (in spring) ( Table 2). While higher TEB values were noted in the soil i tumn, there were no significant differences found in the TEB in the soils sampled from S6, and S8.
The content of AP in the soil ranged from 0.99 to 44.65 mg kg −1 (in spring) (Figu In autumn, the content was significantly higher (p < 0.05) and ranged from 3.92 to 49. kg −1 . The content of available phosphorus varied significantly depending on the soil pling site. The highest accumulation was recorded for the control. In the soil withi influence of the soda plant, the AP decreased, and in the soil from the S1, S3, S6, an sites (only in spring), the lowest AP content was recorded. The AP concentration wa nificantly negatively related to pH in KCl (r = −0.652, p = 0.0033) and ECe (r = −0.48 0.0430). However, the two parameters only in 42.5% and 23.1% determined the vari in AP in the soil. The results of the investigations by Dąbkowska-Naskręt and Bartko [39] in the soil near the soda plant showed that with the cations affecting salinity meas with ECe were calcium and, to a lesser extent, sodium. According to Fageria et al. phosphate availability in saline soils is highly controlled by both sorption processes the low solubility of Ca-P minerals. However, Artamonova, et al. [44] stated that i case of salinization, the degree of Ca 2+ saturation of the soil is reduced due to its rep ment with Na + and Mg 2+ . The toxic effect of Na + increases in the presence of Cl -, sh reducing the absorption of N, P, and K. The regression equation shows that with a crease in pH in KCl by 1 unit, the content of P decreased, lined by 45.83 mg kg −1 . Accor to Bano and Fatima [45], soil salinity and pH > 7.5 significantly reduces the plant P up as phosphate ions precipitate with Ca ions. However Pan et al. [46], Mahmood et al. and Lemanowicz and Bartkowiak [20] reported that most saline soils are adequately plied with P as the content of sodium ions may result in more soluble Na3PO4 b formed. In the soil from S7 (arable field), the content of AP was 24.2 mg kg −1 (spring 39.7 mg kg −1 (autumn), which classifies the soil as part of the IV (low) class of conce tions in P [48]. The soil showed higher AP contents in autumn as compared to sp According to Lu et al. [38], the differences in seasonal nutrient changes across diff sampling areas could have been due to the differences in plant uptake, soil properties hydrological conditions.

Soil Enzyme Activities
The enzymes' activities at all the sites across the months are provided in Table 3 activity of the enzymes is to the parameter specifying the quality soil (e.g., the conte organic matter and cycle of macronutrients including C, N, P, and S). Enzymes ar volved in the breakdown of various types of pollutants (e.g., salinization and heavy als). The impacts of the months and sites of the activities of soil enzymes varied months demonstrated the strongest effect on the activity of CAT (η 2 33.54%) and A 12.6%), and the weakest effect on the activity of AcP (η 2 8.38%).

Soil Enzyme Activities
The enzymes' activities at all the sites across the months are provided in Table 3. The activity of the enzymes is to the parameter specifying the quality soil (e.g., the content of organic matter and cycle of macronutrients including C, N, P, and S). Enzymes are involved in the breakdown of various types of pollutants (e.g., salinization and heavy metals). The impacts of the months and sites of the activities of soil enzymes varied. The months demonstrated the strongest effect on the activity of CAT (η 2 33.54%) and AlP (η 2 12.6%), and the weakest effect on the activity of AcP (η 2 8.38%). The activity of the other enzymes was higher in spring than autumn, which is also seen from the values of coefficient TI < 0 (except for the activity of AlP assayed at soil site 8) ( Figure 5).  The activity of the other enzymes was higher in spring than autumn, which is seen from the values of coefficient TI < 0 (except for the activity of AlP assayed at so 8) ( Figure 5). The seasonal changes in soil enzyme activity are a derivative of the hydrothe conditions; the distribution of temperature and precipitation as the factors with the est effect on the biological activity of soil [49]. Shao et al. [50] stated that the activ some enzymes (urease, invertase, and alkaline phosphatase) had lower activity in w and higher in summer. The analysis of coefficient η 2 has demonstrated that the soil pling around the soda plant accounted for the variation in the activity of enzymes ( line phosphatase accounted for 51%, catalase for 60%, and acid phosphatase for 75. more considerably as compared to the research months (Table 3). There were no sig cant differences found in the activity of catalase in the soil at sites S2, S3, S4, and S5 (T 3). The significantly highest activity of that enzyme was reported at site S1 and the lo at site S8 (spring and autumn). The study of the RCh index of the catalase activities sho that in the soil from sites S1, S2, S3, S4, and S5, the activity increased in comparison t control. In soil sites S6, S7, and S8, the decrease was greater, from 2.88% to 63.94% (F 6). The available literature shows that of all the soil enzymes, the ones most sensiti salinization are oxidoreductases [51][52][53], especially catalase, which is also confirme the present study. The seasonal changes in soil enzyme activity are a derivative of the hydrothermal conditions; the distribution of temperature and precipitation as the factors with the highest effect on the biological activity of soil [49]. Shao et al. [50] stated that the activity of some enzymes (urease, invertase, and alkaline phosphatase) had lower activity in winter and higher in summer. The analysis of coefficient η 2 has demonstrated that the soil sampling around the soda plant accounted for the variation in the activity of enzymes (alkaline phosphatase accounted for 51%, catalase for 60%, and acid phosphatase for 75.57%) more considerably as compared to the research months (Table 3). There were no significant differences found in the activity of catalase in the soil at sites S2, S3, S4, and S5 ( Table 3). The significantly highest activity of that enzyme was reported at site S1 and the lowest at site S8 (spring and autumn). The study of the RCh index of the catalase activities showed that in the soil from sites S1, S2, S3, S4, and S5, the activity increased in comparison to the control. In soil sites S6, S7, and S8, the decrease was greater, from 2.88% to 63.94% ( Figure 6). The available literature shows that of all the soil enzymes, the ones most sensitive to salinization are oxidoreductases [51][52][53], especially catalase, which is also confirmed by the present study. Energies 2021, 14, x FOR PEER REVIEW 10 of 17 The ANOVA analysis indicated that alkaline phosphatase was affected by the method of use of the soil next to the soda plant (p < 0.05) ( Table 4). The highest AlP activity in spring was reported in at soil site S1 (3.124 mM pNP kg −1 h −1 ) and in autumn (1.803 mM pNP kg −1 h −1 ) at soil site S4, whereas the activity of acid phosphatase was highest in the control in spring (4.645 mM pNP kg −1 h −1 ) and autumn (2.894 mM pNP kg −1 h −1 ). In the soil under the impact of the soda industry, the activity of AcP decreased as compared to the control, which is seen from the negative values of coefficient RCh (Figure 6). There were no significant differences identified (p < 0.05) in the activity of AcP across S2, S3, S4, and S5 (spring) ( Table 4). The alkaline phosphatase activities did not exhibit a response to the salinity. Due to the concentration of ions Na+ and Clin the soil solution, salting-out of enzymatic proteins occurred. This involved the reduction in enzyme solubility through dehydration, thus altering the enzyme 'catalytic site' and resulting in a decrease in the activity of enzymes [54]. In addition, this affects enzyme activities by denaturing proteins and decreasing their solubility. The study by Garcia-Gil, et al. [55] showed that soil salinity disperses the fraction clays, resulting in the enzymes becoming less protected and denaturated. Based on the results of the activity of both phosphatases, the enzymatic pH index was calculated (Figure 7). The values at all the soil sampling sites within the impact of the soda plant exceeded the value of 0.5, above which we can consider the soil to be alkaline [31], which is confirmed by the values of pH in KCl. The highest values were recorded at S6, S7, and S8. The ANOVA analysis indicated that alkaline phosphatase was affected by the method of use of the soil next to the soda plant (p < 0.05) ( Table 4). The highest AlP activity in spring was reported in at soil site S1 (3.124 mM pNP kg −1 h −1 ) and in autumn (1.803 mM pNP kg −1 h −1 ) at soil site S4, whereas the activity of acid phosphatase was highest in the control in spring (4.645 mM pNP kg −1 h −1 ) and autumn (2.894 mM pNP kg −1 h −1 ). In the soil under the impact of the soda industry, the activity of AcP decreased as compared to the control, which is seen from the negative values of coefficient RCh ( Figure 6). There were no significant differences identified (p < 0.05) in the activity of AcP across S2, S3, S4, and S5 (spring) ( Table 4). The alkaline phosphatase activities did not exhibit a response to the salinity. Due to the concentration of ions Na + and Cl − in the soil solution, salting-out of enzymatic proteins occurred. This involved the reduction in enzyme solubility through dehydration, thus altering the enzyme 'catalytic site' and resulting in a decrease in the activity of enzymes [54]. In addition, this affects enzyme activities by denaturing proteins and decreasing their solubility. The study by Garcia-Gil, et al. [55] showed that soil salinity disperses the fraction clays, resulting in the enzymes becoming less protected and denaturated. Based on the results of the activity of both phosphatases, the enzymatic pH index was calculated (Figure 7). The values at all the soil sampling sites within the impact of the soda plant exceeded the value of 0.5, above which we can consider the soil to be alkaline [31], which is confirmed by the values of pH in KCl. The highest values were recorded at S6, S7, and S8. The resistance of saline soil is not covered in the literature. The resistance of its ability to renew the balance is for important quality elements and basic indic tween the impact caused by salinization and the soil capacity for regeneration RS values showed that the activities of enzymes varied in their sensitivity to the to the soda plant. According to Orwin and Wardle [32], Borowik and others Bartkowiak et al. [53], the soil resistance factor is an effective measure of enzy sponses to environmental stress. Higher values of index RS show that the dist had an inconsiderable effect (maximum resistance). The highest average RS v noted for catalase (in spring) (RS = 0.702) and the lowest for acid phosphatase (in (RS = 0.261) ( Table 4). Low RS values are indicative of long-term toxic effects of The lowest values of RS for alkaline and acid phosphatase were recorded in the s Regardless of the soil sampling site, enzyme resistance was generally lower in spr autumn, excluding catalase, the resistance of which in spring was 29.6% highe autumn.
The resilience (RL) index is provided in Table 5. The study demonstrated the of acid phosphatase activity (the mean RL = 0.288) and alkaline phosphatase (RL which was proven by the mean positive RL values. In some samples, especially lase, the soil resilience (RL) index was negative. According to Baćmaga et al. [58], the progressing harmful anthropogenic impact on soil biology from spring to au  The resistance of saline soil is not covered in the literature. The resistance of soil and its ability to renew the balance is for important quality elements and basic indicators between the impact caused by salinization and the soil capacity for regeneration [56].
The RS values showed that the activities of enzymes varied in their sensitivity to the soil next to the soda plant. According to Orwin and Wardle [32], Borowik and others [57], and Bartkowiak et al. [53], the soil resistance factor is an effective measure of enzymatic responses to environmental stress. Higher values of index RS show that the disturbances had an inconsiderable effect (maximum resistance). The highest average RS value was noted for catalase (in spring) (RS = 0.702) and the lowest for acid phosphatase (in spring) (RS = 0.261) ( Table 4). Low RS values are indicative of long-term toxic effects of salinity. The lowest values of RS for alkaline and acid phosphatase were recorded in the soil at S6. Regardless of the soil sampling site, enzyme resistance was generally lower in spring than autumn, excluding catalase, the resistance of which in spring was 29.6% higher than in autumn.
The resilience (RL) index is provided in Table 5. The study demonstrated the recovery of acid phosphatase activity (the mean RL = 0.288) and alkaline phosphatase (RL = 0.142), which was proven by the mean positive RL values. In some samples, especially for catalase, the soil resilience (RL) index was negative. According to Baćmaga et al. [58], it reflects the progressing harmful anthropogenic impact on soil biology from spring to autumn. Statistical analysis correlation proved that the enzymes and AP in the soil were correlated with some parameters at p < 0.05 (Table 6). In our research, catalase proved to be more affectionate to soil salinization. With the analysis of the relation, there was a positive dependence found between the activity of catalase and EC e (r = 0.623, p = 0.0057), and a negative dependence with TEB (r = −0.523, p = 0.0258), while the inhibition of the activity of catalase depended on the increasing content of salt in the soil due to the introduction of sodium chloride as reported by Telesiński [52]. The activity of acid phosphatase was also negatively correlated with TEB (r = −0.497, p = 0.0355). According to Pan et al. [45], the enzyme activity related to the salinity of the soil varied depending on the type of enzyme and degree of salinization. Catalase takes part in the defense of the plants against external factors triggering oxidation stress in plants such as growing in saline soils. In saline soils, the process of protein salting-out occurs, therefore enzymes lose their biological activity. The study by Aechra et al. [59] revealed that the application of high soil salinity decreased the concentration of TP and AP, and the activity of DEH and AlP. In contrast, the study by Shirale et al. [60] demonstrated that the soils containing high amounts of Na + hindered the microbial number under the restricted use of organic supplements, which resulted in a decrease in the activity of AcP of Mollic Gleysols. Acid phosphatase activity was positively related with AP (r = 0.597, p = 0.0089), which indicates that the soil was more effectively organic P-mineralizing. The explanation of that phenomenon is complex because there is a probability of a long-term occurrence of soil enzymes in bonds with colloids. The activities of enzymes are correlated with soil organic matter concentration as they plays the key role as initiators for enzyme synthesis. However, in our study, the correlation between TOC and AcP was negative (r = −0.509, p = 0.0355). There was a negative correlation found between the content of CaCO 3 , the AlP (r = −0.595, p = 0.0092), and AcP (r = 0.527, p = 0.0244). However, according to Acosta-Martínez and Tabatabai [61], the alkaline and acid phosphatases react to lime differently because these enzymes are inductive and the intensity of their excretion by plant roots and microorganisms is determined by their requirement for orthophosphate, which is affected by soil pH. The research showed that CAT, AlP, and AcP were all positively significantly related with each other ( Table 6), indicating that the enzyme activity can other the activity of another enzyme in the soil to a large extent. Another measure to evaluate the dependence of the activity of CAT, AlP, and AcP on physical and chemical soil properties is the regression equation and the R 2 . With the value of R 2 , it was found that the activity of catalase was only 38.8% dependent on EC e and 27.3% on TEB. Similarly, the activity of AcP was only 24.7% dependent on TEB and 25.9% on TOC, while about 75% can be accounted for by other soil parameters. In terms of the content of AP, only 23.1% was dependent onEC e , 42.5% by pH KCl, and 37.2% by CaCO 3 . The regression equation shows that with an increase in pH by 1 unit, the content of AP decreased by 45.83 mg kg −1 .
To define the nature and strength of dependencies of CAT, AlP, and AcP to the selected soil properties (grain size composition, pH in KCl, TOC, NT, AP, and TEB) and environmental variables, the principal component analysis (PCA) was applied. The drawing (Figure 8) shows that three principal hypothetical reasons of variation (PC1, PC2 and PC3) allowed to account for a total of 92.72% of the variation.  [62] showed that these f can be assumed as strong (>0.750). The use of the PCA is important in the interpre of how the soil is used because it can identify soil-next-to-soda-industry variables th be excluded to remove repetitive and difficult-to-measure information. PCA is f through the method for selecting more effective indexes in soil sustainability [63].   Table 7). The PC2 accounts for 31.98% of the variable data. It showed a negative correlation with the activity of CAT (−0.865), EC e (−0.860), and clay (−0.758). The PC3 describes the role of NT (0.793) and TEB (0.859), and it accounts for 19.37% of the total variation ( Figure 8). Research by Liu et al. [62] showed that these factors can be assumed as strong (>0.750). The use of the PCA is important in the interpretation of how the soil is used because it can identify soil-next-to-soda-industry variables that can be excluded to remove repetitive and difficult-to-measure information. PCA is found through the method for selecting more effective indexes in soil sustainability [63]. To determine the similarities across the eight sites next to the soda plant and the control, the grouping method by Ward [35] was used. Physicochemical and enzymatic soil properties were applied. The results of the cluster analysis (CA) are shown with the dendrogram in Figure 9. The grouping procedure differentiated two clusters with soils with similar properties and one outlier (S1 is the lowest phosphorus content and the highest EC e ). Cluster 1 groups soils S2, S4, S5, S7, and the control (the highest phosphorus content and the lowest EC e ), while cluster 2 groups soils S3, S6, and S8, which differed from the control soil in terms of the properties studied (the highest TOC, TEB, and CaCO 3 content).
Energies 2021, 14, x FOR PEER REVIEW 14 similar properties and one outlier (S1 is the lowest phosphorus content and the hi ECe). Cluster 1 groups soils S2, S4, S5, S7, and the control (the highest phosphorus co and the lowest ECe), while cluster 2 groups soils S3, S6, and S8, which differed from control soil in terms of the properties studied (the highest TOC, TEB, and CaCO3 con

Conclusions
The seasonal dynamics of AP and the activity of AlP, AcP, and CAT were ass in the area of sustained emissions of soda compounds. Technogenic salinization resu the formation of soils that have no natural counterparts. The presented research re have shown no one-way changes in the study parameters. The parameters differe pending on the soil sampling site. The values of coefficients RS, RL, RCh, and TI demonstrated the direction of transformations of the enzymes depending on the an pogenic and seasonal factors. The concentration of AP was lower in spring than aut Changes that occur in technogenic saline soils as a result of a constant supply of N quire continuous enhancement and further development of the knowledge on the ac of enzymes and P compounds in soil. This research shows that irrespective of th sampling locations, the mean values of RS allow us to arrange the enzymes in resp their tolerance to the impact of anthropopression: in spring, CAT (0.702) > AlP (0.5 AcP (0.261), and in autumn, AlP (0.553) > CAT (0.494) >AcP (0.299). The recovery o activity (index RL), though, was demonstrated only by AcP (0.288) and AlP (0.142).
Dynamic transformation in the activity of soil enzymes are strongly related t water content and temperature; however, they also coincide with anthropogenic acti and their consequences.
The present correlation study and multivariate analysis (CA and PCA) can he select a few parameters that could be frequently measured to determine the status o and to take measures to prevent the deterioration of soil. It is important that the enzy activity in the salt-affected soils in this study are tested at a minimum of two consec years later, which may show that the soil properties have become more stable and t fore research should be continued.

Conclusions
The seasonal dynamics of AP and the activity of AlP, AcP, and CAT were assessed in the area of sustained emissions of soda compounds. Technogenic salinization results in the formation of soils that have no natural counterparts. The presented research results have shown no one-way changes in the study parameters. The parameters differed depending on the soil sampling site. The values of coefficients RS, RL, RCh, and TI have demonstrated the direction of transformations of the enzymes depending on the anthropogenic and seasonal factors. The concentration of AP was lower in spring than autumn. Changes that occur in technogenic saline soils as a result of a constant supply of Na + require continuous enhancement and further development of the knowledge on the activity of enzymes and P compounds in soil. This research shows that irrespective of the soil sampling locations, the mean values of RS allow us to arrange the enzymes in respect to their tolerance to the impact of anthropopression: in spring, CAT (0.702) > AlP (0.553) > AcP (0.261), and in autumn, AlP (0.553) > CAT (0.494) > AcP (0.299). The recovery of the activity (index RL), though, was demonstrated only by AcP (0.288) and AlP (0.142).
Dynamic transformation in the activity of soil enzymes are strongly related to the water content and temperature; however, they also coincide with anthropogenic activities and their consequences.
The present correlation study and multivariate analysis (CA and PCA) can help to select a few parameters that could be frequently measured to determine the status of soil and to take measures to prevent the deterioration of soil. It is important that the enzymatic activity in the salt-affected soils in this study are tested at a minimum of two consecutive years later, which may show that the soil properties have become more stable and therefore research should be continued.