Salinization Processes Research Articles

Salt Stress in Plants and Mitigation Approaches.

Salinization of soils and freshwater resources by natural processes and/or human activities has become an increasing issue that affects environmental services and socioeconomic relations. In addition, salinization jeopardizes agroecosystems, inducing salt stress in most cultivated plants (nutrient deficiency, pH and oxidative stress, biomass reduction), and directly affects the quality and quantity of food production. Depending on the type of salt/stress (alkaline or pH-neutral), specific approaches and solutions should be applied to ameliorate the situation on-site. Various agro-hydrotechnical (soil and water conservation, reduced tillage, mulching, rainwater harvesting, irrigation and drainage, control of seawater intrusion), biological (agroforestry, multi-cropping, cultivation of salt-resistant species, bacterial inoculation, promotion of mycorrhiza, grafting with salt-resistant rootstocks), chemical (application of organic and mineral amendments, phytohormones), bio-ecological (breeding, desalination, application of nano-based products, seed biopriming), and/or institutional solutions (salinity monitoring, integrated national and regional strategies) are very effective against salinity/salt stress and numerous other constraints. Advances in computer science (artificial intelligence, machine learning) provide rapid predictions of salinization processes from the field to the global scale, under numerous scenarios, including climate change. Thus, these results represent a comprehensive outcome and tool for a multidisciplinary approach to protect and control salinization, minimizing damages caused by salt stress.

Spatial patterns of soil salinity in the central Argentinean Dry Chaco

The Dry Chaco is a semi-arid ecoregion in South America that hosts one of the largest dry forests in the world, but expansion of dryland agriculture and cattle ranching led to gradual conversion of native vegetation to anthropogenic land cover. The potential impact of these newly established agricultural lands on the surrounding environment is of great concern. Local studies have shown that deforestation leads to changes in the soil-water balance, and can expedite groundwater rise and mobilization of water-soluble salts to the surface affecting plant growth and crop productivity. This study is a regional assessment of soil salinity and salinization processes in the central Argentinean Dry Chaco. It is based on extensive dataset of 492 surface and 142 subsurface samples taken along east-west transects across the Dry Chaco. Soil electrical conductivity (EC) was used as an indicator of salinity, and supplementary information on salt crusts was derived from Google Earth imagery. Subsurface salinity (i.e., measured at 100 cm depth) showed clear regional patterns in natural soil salinity that are related to the annual water budget and topography. Besides primary salinization due to arrested drainage and landscape stagnation, anthropogenic activities increased secondary salinization, especially in the agricultural areas with shallow groundwater tables and irrigated croplands. In addition, the study demonstrated that remotely-sensed vegetation indices such as the seasonal variation in the density of green vegetation are particularly suitable to monitor regional variation in soil salinity. Our results show that the extent of future dryland salinization in the Dry Chaco will mainly depend on whether areas prone to natural soil salinity are further protected from deforestation, and the magnitude and rate of groundwater rise after deforestation as conditioned by local climate and geomorphology. This better understanding of soil salinity patterns and how they are affected as a result of anthropogenic activities is important for the implementation of appropriate and effective measures to prevent severe salinization.

Chemical Quality of Waters of the Atoyac-Verde River As It Passes Through Forest Ecosystems of Oaxaca, Mexico

In granitic regions, water salinity typically ranges from 30 to 40 mg L−1 at the surface and from 300 to 500 mg L−1 for groundwater. Technogenic activity in Oaxaca has altered the concentration and chemical composition, which explains the occurrence of salinization processes and contamination of natural waters. To determine the physical–chemical composition of the Atoyac-Verde river, fifty-two water samples were collected from tributaries and semi-deep wells in the basin. The pH, electrical conductivity (EC), major cations and anions, total dissolved solids (TDS), residual sodium carbonate (RSC), and sodium adsorption ratio (SAR) were identified. Likewise, osmotic potential (Ψπ) was evaluated, and the effective salinity (ES) and potential salinity (PS) indexes. Results indicate that the water of the basin is bicarbonate-magnesium-calcium. Of the 52 samples analyzed, only 2 identified in the high relief points presented high levels of alkalinity and salinity with a pH of 8.1, EC of 2320 µS cm−1, Ψπ of − 0.08 MPa, SAR of 3.74 (mmolc L−1) 1/2, RSC of 0.53, ES of 9.88, and PS of 7.79 mmolc L−1, indicating restriction for its use in agricultural and domestic activities. In the meso relief, the water did not present restrictive levels for anthropic use, while in the low relief, only two points presented high salinity levels and restriction of anthropic use. In conclusion, the greatest chemical alteration of the water was detected in areas close to the city of Oaxaca and to a lesser extent in areas adjacent to riverside populations of more than 2500 inhabitants.

Hydrogeochemical Characterization and Identification of Factors Influencing Groundwater Quality in Coastal Aquifers, Case: La Yarada, Tacna, Peru.

The coastal aquifer La Yarada has anthropogenic and geogenic contamination that adversely affect the quality of groundwater for population and agricultural use. In this scenario, multivariate statistical methods were applied in 20 physicochemical and isotopic parameters of 53 groundwater pumping wells in October 2020, with the aim of characterizing the hydrogeochemical processes that dominate the groundwater of the coastal aquifer and the factors that cause them to optimize the effective management of water resources, delimiting areas affected by more than one salinization process. The samples were grouped into three clusters (C1, C2, and C3) with cluster analysis, the spatial distribution of C2 and C3 (reclassified in stiff diagrams), evidenced hydrogeochemical facies associated with the flow and recharge directions governed by the structural lineaments (NE-SO), favoring some areas more than others, arising different facies and hydrogeochemical processes. Factor analysis was applied from three different approaches: (1) main elements, (2) trace elements, and (3) physicochemical and isotopic parameters; exposing 6 distinguishable hydrogeochemical processes in the aquifer and factors that cause them: (i) salinization—marine intrusion, (ii) fertilizer leaching and dissolution of (Ca2+, Mg2+), (iii) wastewater mixture (NO3−), (iv) reducing conditions (Fe, Mn, Al), (v) contributions of (B, Sr), (vi) conservative mixtures and dissolution (As, F). It was validated with water quality indices (WQI) according to the national limits, delimiting 67 km2 parallel to the coast with “bad” to “very bad” quality for human consumption and unsuitable for irrigation according to the Wilcox diagram thus pre-treatment in this area is indispensable.

Moisture and Salinity Distribution around the Root of Drip-tape-irrigated Maize Cultivated in Heavy Soil of Khuzestan Province of Iran

ABSTRACT Limited water resources have increased the need for optimal use of water in agriculture. One solution in this regard is to employ modern irrigation methods, including drip tape irrigation. In this study, furrow surface irrigation (the standard method used in the local area) was compared with a drip tape irrigation system under three irrigation regimes (two-, three-, and four-day regimes). Soil moisture and salinity during every stage of plant development (primary, middle, and final) were monitored by collecting soil samples from 0–25, 25–50, and 50–75 cm depths before and after irrigation. Similar moisture distribution was achieved in the 2 consecutive crop years. Under the 2 day irrigation regime, the most substantial moisture changes were observed in the 0–25 cm deep layer and under 3 and 4-day irrigation regimes in the 0–50 cm depth. Soil moisture content before irrigation was around 16 wt.%, reaching 18% after the 2 day irrigation treatment and 23% after 3 and 4 day irrigation treatments. Salinity in the 2-day EC irrigation regime, the soil salinity has decreased from 9 to 5 dS/m in the first year and from 11.5 to 2.8 dS/m in the second year, and in 3- and 4-day irrigation regimes, soil EC has increased from 9 to 10 ds/m in the first year and from 11.5 to 4.5 dS/m in the second year. The study of salinity distribution at different depths of plant roots introduces the best soil depth to 0 to 25 cm with the lowest salinity in all three irrigation regimes. In contrast, by the end of the second crop year, salinity dropped to a quarter, which was primarily due to the better water quality of The Karun River compared to the previous year. A similar outcome was achieved with surface irrigation. The results show that replacing tape strip irrigation with surface irrigation, in addition to saving on the amount of irrigation water consumption, also controls the soil salinization process by applying irrigation management and choosing the best irrigation regime.

Современная сравнительная характеристика горно-луговых почв Азербайджана

The northeastern slope of the Lesser Caucasus occupies a large territory in the western part of Azerbaijan. One of the most widespread soils in Azerbaijan is mountain meadow soils. The purpose of the research is a comprehensive and comparative study of morphodiagnostic parameters, physicochemical properties and biochemical activity of natural and anthropogenically modified biogeocenosis of mountain meadow soils of the Gadabay District. Some results of many years study are described in the article. Villages like Gara Murad, Kichik, Garamurad, Saratovka and others were researched. The research was carried out on virgin soils and cultivated lands in villages. A total of 15 land plots have been allocated, some of the research results are presented in the article. Carrying out numerous agro-reclamation activities, we managed to attract uncultivated land to agriculture and obtain high-quality products. The groundwater level in these areas exceeds 2 meters, and the salinization processes are active. Comparative results from all these agro-chemical studies helped to get virgin soils into agriculture in the plains and achieve high productivity. This can be invaluable literary material for a new generation of soil scientists.

Identifying the Major Hydrogeochemical Factors Governing Groundwater Chemistry in the Coastal Aquifers of Southwest Bangladesh Using Statistical Analysis

People in the southwestern (SW) coastal part of Bangladesh are suffering from a severe freshwater crisis due to saline groundwater at a shallow depth. Fresh groundwater below a 200 m depth is an option, but it is costly to construct deep tubewells for the local inhabitants. The processes of salinization and freshening were previously identified using conventional methods. In this study, we brought new insight into these processes by analyzing existing datasets using multivariate statistics to identify the factors affecting groundwater chemistry. Cluster analysis (CA) revealed three major clusters. Cluster A corresponded to saline (NaCl-type) water. Cluster B was also saline (NaCl-type) water but showed mixing effects. Cluster C was fresh groundwater (NaHCO3-type) and isolated. The hydrochemical characteristics of clusters A, B and C compared remarkably well with the groundwaters from the upper shallow aquifer (USA), lower shallow aquifer (LSA) and deep aquifer (DA), respectively. Factor analysis (FA) showed that 75% of the total variance was influenced by evaporate dissolution, carbonate dissolution/precipitation, cation exchange and anthropogenic pollution to some extent. Therefore, the integrated approach showed the validity of applying multivariate statistical techniques to infer the dominant hydrochemistry and to characterize and understand a complicated hydrogeological system.

Origins and processes of groundwater salinisation in Barka coastal aquifer, Sultanate of Oman

The quality of groundwater resources in many coastal aquifers in the world is threatened by salinity due to several contamination sources and processes. The aim of this work is to identify the sources of salinity and to improve understanding of the major processes controlling groundwater chemistry in Barka coastal region, Sultanate of Oman. Data of pH, EC and concentration of major ions available for 99 groundwater samples in spring 2010 were analysed using statistical and multivariate tools, PHREEQC code and molar ratios. The EC of the groundwater varied from 1,252 to 25,800 μS/cm with an average value of 8,409 μS/cm. Three water types were found in the groundwater: Ca–Mg–Cl, Na–Cl and Ca–Cl. They suggest the mixing of freshwater infiltrated from rock aquifers of Jabal Al Akhdar Mountain with the salt water caused from seawater intrusion followed by reverse cations exchange reactions. Piezometric map, and geochemical criteria and indices confirmed the occurrence of seawater intrusion into the coastal aquifer. The mixing rate of freshwater-seawater ranged from 0.04% to 57.72% through the study area. PHREEQC modelling shows that the groundwater was under-saturated with halite, anhydrite and silica, and saturated with calcite and dolomite. Pearson's correlations, principle component analysis, ionic changes (Nachange, Cachange, Mgchange and Kchange), scatter diagram and diagrams of some cations versus Cl− justified that dissolution of halite, anhydrite and silica minerals, and reverse cations exchange reactions controlled the groundwater chemistry in the study area.

Application of Aqueous Saline Process to Extract Silkworm Pupae Oil (Bombyx mori): Process Optimization and Composition Analysis.

Silkworm pupae, a waste product from the silk production industry, can be an alternative source of edible oil, thus reducing the industry’s waste. In the present work, frozen silkworm pupae were used as raw material to extract oil via an aqueous saline process. The Box–Behnken design (BBD) and response surface methodology (RSM) were used to optimize the extraction process. The extraction conditions with the highest oil yield and a low peroxide value were obtained when using a saline solution concentration of 1.7% w/v, a ratio of aqueous liquid to silkworm pupae of 3.3 mL/g, and a 119 min stirring time at the stirring speed of 100 rpm. Under these conditions, silkworm oil with a yield of 3.32%, peroxide values of approximately 1.55 mM, and an acid value of 0.67 mg KOH/g oil was obtained. The extracted oil contained omega-3 acids (α-linolenic acid), which constituted around 25% of the total fatty acids, with approximate cholesterol levels of 109 mg/100 g oil. The amounts of β-carotene and α-tocopherol were approximately 785 and 9434 μg/100 g oil, respectively. Overall, the results demonstrated that oil extracted from silkworm pupae has good quality parameters and thus can be used as a new valuable source of edible lipids.

Spatial Analysis of the Chemical Regime of Groundwater in the Karatal Irrigation Massif in South-Eastern Kazakhstan

Understanding the groundwater chemical regime on irrigated lands is relevant for assessing hydrogeological and reclamation processes. Water chemistry, natural and climatic conditions, and drainage characteristics define the complex hydrochemical connections which are formed between irrigation waters, soil, and water of the unsaturated zone and groundwater. This research paper presents the results of studies of seasonal changes in the chemical composition of groundwater in the Karatal irrigated massif. A detailed analysis of the salt regime and chemical composition of groundwater have been performed based on a large number of samples for 2019. Besides, data related to the Karatal River and drainage waters quality inside the basin have also been analyzed. Results demonstrate that the salinization processes in the massif are determined by hydrogeological conditions and drainage availability. In the north-eastern part of the massif, a high risk of soil salinization has been observed as a consequence of all the salinization processes which are determined by its hydrogeological conditions and drainage availability. Data analysis over soil samples and irrigation and drainage waters show that the hydrochemical regime of groundwater on Karatal irrigation massif is influenced by the presence of saline soil-forming rocks, the groundwater depth, the volume, and the quality of irrigation waters, the characteristics of the natural drainage, and evaporation processes.

Isotopic and hydrochemical evidence for the source and mechanism of groundwater salinization in Kashan Plain aquifer in Iran.

Groundwater salinization and interaction between Playa Lake and regional groundwater were investigated using multi-chemo-isotopic evidences. Forty groundwater and 26 Kashan Playa Lake (KPL) water samples were collected and analyzed for their geochemical compositions. The evolution of hydrochemical facies in Kashan Plain Aquifer (KPA) to KPL is Ca-HCO3 (19%), Mix Ca-Cl (9%), Ca-Cl (17%), and Mix Na-Cl and Na-Cl (55%). Also, the Hydrochemical Facies Evolution Diagram (HFE-D) proposed cation exchange as the main process of salinization in KPA. Based on the binary hydrogeochemical diagrams of (Na+/Cl-)/Cl-, (Ca2+ + Mg2+)/HCO3- + SO42-, and Cl/Br, dissolution of halite and gypsum in the Miocene marlstone in the KPA is the main source of salinity. The δ18O of waterin aquifer and playa water samples varies from -10.03 to 7.03‰ (VSMOW) with an average of -6.95‰ and -60.73 to 25.08‰ with average of -45.82‰ for δ2H. Based on the results, the relation between δ18O and δ2H, and δ18O and Br, approves discharge of saline water from KPA to KPL. Likewise, the isotopic composition of δ34SO4, varies from 5.95 to 22.55‰ CDT in KPA, and 5.95 to 9.99 ‰ CDT in KPL. Also, the relations between δ18O-δ34SSO4 and Cl-δ34S were non-linear, indicating that sulfur concentration in KPA and KPL changed due to sulfide oxidation and sulfate reduction in the freshwater and deep brines in the aquifer and mixed during the over-pumping in the KPA. Oxidation of sulfide minerals in the mineralized region in the western part of the aquifer (recharge zone) may have been the source of sulfur leached by seasonal runoff. Water-rock interaction, ion exchange, and hydraulic gradient have been the dominating factors in changing the water chemistry between aquifer and playa leading to saline groundwater discharged to the playa.

Environmentally significant indicators of mountain meadow soils in Azerbaijan

The most widespread soils in the Republic of Azerbaijan are mountain-meadow soils. The aim of the research was a comprehensive and comparative study of morphodiagnostic parameters, physical and chemical properties, as well as the biochemical activity of natural and anthropogenically modified biogeocenoses of the Kedabey region. The area has unique flora and fauna. Surroundings of the villages Gara Murad, Kichik Garamurad, Saratovka and others were investigated. The research was carried out on virgin and cultivated lands in villages. The degree of mineralization of the rivers Zayamchay and Chekhrichay ranges from 140 to 430 mg. The groundwater level in these areas exceeds 2 m, salinization processes are active. A herbarium was collected and the floristic composition of natural cenoses was determined. Invertebrates were also collected and the dominant composition of the fauna of natural cenoses was determined. Of the saprophages in these biocenoses, woodlice of the genus Hemilepisthus and Armadillidium are widely used. The most intensive decomposition of the remains of cereal vegetation is observed in the soil of the coastal strip (65.9%). In the natural cenosis, the rate of destruction of saltwort and salt-tolerant grass vegetation reaches 44.3%. The main role in the destruction of plant remains is played by a group of saprphages, which actively use plant litter. The decomposing material reaches its final stage of microbiological transformation. The duration and amount of CO2 in different soil horizons were also studied. It has been established that with increasing depth, the amount of carbon dioxide decreases. The hydrolytic activity of invertase and urease enzymes in the studied soils can be assessed as very weak. Comparative results of all these agrochemical studies helped to develop virgin soils in agriculture on the plains and achieve high productivity.

Irrigation quality and management determine salinization in Israeli olive orchards

Abstract. Olive (Olea europaea L.) orchard brackish water irrigation with incorrect irrigation management reduces soil fertility and degrades soil health through soil salinization. This study was conducted in the Beit She'an Valley, one of the main agricultural regions in Israel, in an olive orchard in which a combination of soil salinization and poor drainage conditions impedes plant development and causes severe economic damage. By combining various research methods, including soil salinity monitoring, field experiments, remote sensing (frequency domain electromagnetic – FDEM), and unsaturated soil profile saline water movement modeling, the salinization processes were quantified. Irrigation water conductance of 3.13 dS m−1 points to salinization within the tree upper root zone, whereas the modeling results suggest that salinization danger is greater with brackish treated wastewater rather than with lower-salinity brackish irrigation groundwater and that irrigation with potable water can help reduce salt accumulation and recover damaged plots.

Recharge mechanism and salinization processes in coastal aquifers in Nam Dinh province, Vietnam

In Nam Dinh province, in the Red River delta plain in Northern Vietnam, groundwater in the shallow Holocene aquifer shows elevated total dissolved solids up to 35 km from the coastline, indicating a saltwater intrusion from the Gulf of Tonkin. High groundwater salinities have been encountered below and adjacent to the Red River in the deep Pleistocene aquifer. Since 1996, large-scale groundwater abstraction was initiated from the deep aquifer, and the observed elevated salinities now raise concerns about whether the groundwater abstraction is undertaken sustainably. We have conducted a study to obtain a fundamental understanding of the recharge mechanisms and salinization processes in the Nam Dinh province. A holistic approach with multiple methods including transient electromagnetic sounding and borehole logging, exploratory drilling, sampling and analyzing primary ion and stable isotope compositions of water and pore water, groundwater head monitoring, hydraulic experiments laboratory of clay layers, and groundwater modeling by using the SEAWAT code. Results reveal that saline river water is leached from the Red River and its distributaries into the shallow aquifers. The distribution and occurrence of salty pore water in the Holocene aquitard clay shows that meteoric water has not been flowing through these low permeable clay layers. Marine pore water has, however, been leached out of the Pleistocene clay. When this layer is present, it offers protection of the lower aquifer against high salinity water from above. Salinity as high as 80 % of oceanic water is observed in interstitial pore water of the transgressive Holocene clay. Saltwater is transported into the Pleistocene aquifer, where the Holocene clay is directly overlying the aquifer.

Evaluation of Groundwater Quality in the Deep Maastrichtian Aquifer of Senegal Using Multivariate Statistics and Water Quality Index-Based GIS

A regional groundwater quality evaluation was conducted in the deep Maastrichtian aquifer of Senegal through multivariate statistical analysis and a GIS-based water quality index using physicochemical data from 232 boreholes distributed over the whole country. The aim was to 1) identify the water types and likely factors influencing the hydrochemistry, and 2) determine the suitability of groundwater for drinking and irrigation. Results showed that sodium, chloride, and fluoride are highly correlated with electrical conductivity (EC) reflecting the significant contribution of these elements to groundwater mineralization. The principal component analysis evidenced: 1) salinization processes (loaded by Na+, K+, EC, Cl-, F- and HCO3-) controlled by water/rock interaction, seawater intrusion and cation exchange reactions; 2) dolomite dissolution loaded by the couple Ca2+ and Mg2+ and 3) localized mixing with upper aquifers and gypsum dissolution respectively loaded by NO3- and SO42-. The hierarchical clustering analysis distinguished four clusters: 1) freshwater (EC = 594 μs/cm) with mixed-HCO3 water type and ionic contents below WHO standard; 2) brackish (Na-mixed) water type with moderate mineralization content (1310 μs/cm), 3) brackish (Na-Cl) water type depicted by high EC values (3292 μs/cm) and ionic contents above WHO and 4) saline water with Na-Cl water type and very high mineralization contents (5953 μs/cm). The mapping of the groundwater quality index indicated suitable zones for drinking accounting for 54% of the entire area. The occurrence of a central brackish band and its vicinity, which were characterized by high mineralization, yielded unsuitable groundwater for drinking and agricultural uses. The approach used in this study was valuable for assessing groundwater quality for drinking and irrigation, and it can be used for regional studies in other locations, particularly in shallow and vulnerable aquifers.

ЭФФЕКТИВНОСТЬ ИСПОЛЬЗОВАНИЯ ФОСФОГИПСА С ОРГАНИКОЙ ДЛЯ ПОЧВ КОМПЛЕКСНОГО ПОКРОВА ПРИ ОРОШЕНИИ

Purpose: to determine the impact of phosphogypsum rates in combination with organic matter on the properties of integrated cover soils, their productivity, and also to substantiate the economic feasibility of their application for chemical reclamation during irrigation. Materials and methods. The studies were carried out in the Martynovsky district Rostov region for 4 years on the integrated cover soils according to the scheme of the experiment, including the application of phosphogypsum (Ph) and organic matter (OM) at certain rates. The studies were carried out according to generally accepted methods. Results. It has been stated that the phosphogypsum application at 10 t/ha rate contributed to the southern chernozem desalination up to 3 % sodium from the total soil-absorbing complex and an calcium and magnesium increase to the optimal parameters for this soil. On the solonetz, the content of exchangeable sodium decreased to 9–8 % in the variants with 10 t/ha Ph rate. In the variant with 5 t/ha Ph rate, the process of soil salinization proceeded somewhat more slowly, which is associated with an insufficient ameliorant rate for the solonetz. The accumulation of humus to the greatest extent was observed in the variant 10 t/ha Ph + 40 t/ha OM. After 4 years, it amounted to 0.24 % on the southern chernozem, and 0.19 % on the solonetz. Both soils included in the complex decompacted, and in the better option, the southern chernozem density was 1.17 t/m³, and on the solonetz – 1.20 t/m³. The soil properties improvement contributed to the increase in productivity. By the 4th year of the aftereffect of ameliorants, it increased by 73–85 % on the southern chernozem and by 69–79 % on solonetz compared with the control. The average productivity for 4 years of research on the southern chernozem ranged from 7.18 (5 t/ha Ph + 40 t/ha OM) to 8.03 t grain units/ha (10 t/ha Ph + 40 t/ha OM), and in the control 4.82 t grain units/ha. On the solonetz, respectively, it increased from 6.03 to 6.93 t grain units/ha, in the control – 4.30 t grain units/ha. Conclusions: the application of phosphogypsum with organic matter provides both reclamative and economic effect on solonetz integrated cover soils.

Оценка пригодности очищенных хозяйственно-бытовых сточных вод КОС «Кадамовские» для орошения

The purpose of the research is to study the chemical composition of treated domestic wastewater and to assess the potential capability of their use for irrigation purposes. The object of the study is domestic wastewater from the «Kadamovskie» WWTP, Novocherkassk, after mechanical and biological treatment. Research methods included the determination of the wastewater suitability according to the following indicators: the concentration of toxic salts, the ratio of cations, the content of the main biogenic elements (NPK), the irrigation coefficient according to Stebler, the ion exchange coeffi cient by I.N. Antipov-Karataev and G.M. Kader, sodium-adsorption ratio (SAR), risk of magnesium alkalinization (Sabolch and Darab). For studying the chemical composition of treated domestic wastewater, wastewater samples were taken from the «Kadamovskie» WWTP in Novocherkassk and their chemical composition was determined in an accredited environmental analytical laboratory of the Federal State Budget Scientifi c Institution RosNIIPM. Based on laboratory results, wastewater is classifi ed as lowmineralized (1.0…3.0 g/dm3), according to the degree of mineralization. Wastewater (after mechanical and biological treatment) belongs to class III and is characterized as satisfactory. In accordance with the soil-reclamation classifi cation, its suitability for irrigation is limited due to the possibility of chloride salinization processes development. According to calculations based on irrigation coefficients, ion exchange coefficients and sodium adsorption ratio, treated domestic wastewater is suitable for irrigation and it doesn’t cause soil salinity hazard (soil alkalization). Thus, it is recommended to consider treated domestic wastewater from the «Kadamovskie» WWTP in Novocherkassk as an alternative source of irrigation water.

Ecological and geochemical state of soils and grounds of Moscow green spaces (analytical review)

The paper assesses the pollution of soils and grounds of green spaces in Moscow with heavy metals and de-icing agents. The analysis of literature sources indicates a decrease in integral pollution index of soils and grounds of green spaces in the city in recent years. The decrease in the integral pollution index is determined by the reduction of emissions from industrial enterprises and by the land reclamation with the replacement of the upper soil layer. At the same time, an observed increase in the lead concentrations in urban landscapes was caused by intensive automobile traffic. The lack of green territories was noted in central part of the metropolis, which is below the norm recommended by WHO (50 m2 of tree plantations per person). The processes of soil salinization and suppression of urban vegetation caused by the use of de-icing reagents are described. The literature data on the anthropogenic transformation of physical and chemical properties of soils and forms of heavy metal compounds in soils are presented. It is indicated that the study of these issues is promising for solving ecological-hygienic problems of the megalopolis. Soils of green spaces in Moscow are proposed to be divided into three groups, taking into account the genesis, ecological and geochemical state: 1) soils on artificial bulk ground of designed landscapes, 2) transformed soils with traces of past anthropogenic impact (postagrogenic soils, soils of post-settlement territories, 3) soils on the territories of parks, forest parks and forests, slightly affected by human activities and retaining the properties of natural zonal soils.

Impact of anthropogenic activity on the chemical regime of underground waters


 
 
 
 The article is dedicated to definition of the tendency to change and pattern of formation of the chemical regime of underground waters in the Turyanchay-Girdimanchay interfluve in the Shirvan steppe, Azerbaijan as a result of anthropogenic activity. The subsoil waters studied are spread in the zone between the Turyanchay and Girdimanchay rivers. From 1930 to 2019 based on analysis of the observation of the chemical regime of subsoil waters, the natural regime of the groundwaters in the studied area strongly changed as a result of irrigation and construction works. In 1930 the average mineralization degree of subsoil waters was 26.8 gram/liter in the zone. The level of subsoil waters approaches the surface and is exposed to strong evaporation as a result of irrigation and filtration of waters from irrigation channels. Consequently, the mineralization rate of subsoil waters increased and mass secondary salinization process occurred in the irrigated lands. The average mineralization degree of subsoil waters was 33.6–34.5 gram/liter in the research zone in the 1960s-1970s. Collector-drainage networks were built and basic washing of soils is carried out in order the prevent secondary salinization and regulate the level of subsoil waters. After the 1970s the mineralization rate of subsoil waters began to decrease due to basic washing, intensive irrigation and the activity of the collector-drainage network.The average mineralization degree decreased to 15.1 gram/liter. The mineralization degree of the water in the Main Shirvan Collector which takes subsoil waters formed in the zone with 253,000 hectares and which discaharges them into the Caspian Sea decreased more than 3 times in comparison with 1995. At present the mineralization degree of collector water is 1.8–2.5 gram/liter while its mineralization degree was 8.81 gram/liter in 1995. Formation of the process in a favourable direction enchances the potential of using collector water for irrigation, technical and other purposes and creates a basis for elimination of water deficiency in drought years. The research shows that anthropogenic activity mainly plays an important role in formation of the chemical regime of subsoil waters.
 
 
 

Hydrochemical Indicators Analysis of Seawater Intrusion in Coastal Karstic Aquifers on the Example of the Bokanjac-Poličnik Catchment Area in Zadar, Croatia

Monitoring and detection of seawater intrusion in coastal aquifers in Croatia are one of the water management measures that attempt to notice an increase in salinity in time. Bokanjac-Poličnik is the coastal aquifer in Croatia that is at the risk of seawater intrusion. In that area, analysis of hydro-chemical indicators will be conducted due to the occasional seawater intrusion that occurs on wells that are included in the water supply system for the City of Zadar and surrounding villages. Due to the increased exploitation during the tourism season in summer and climate changes, salinization process is more intense. The presented results indicate that two of four wells on the case study area are under the influence of salt marine water.