Sorption Properties Of Soil Research Articles

THE ROLE OF LIMING IN COPPER ADSORPTION OF ACIDIC SOILS

Investigate the impact of varying rates of liming on the availability and sorption properties of copper in a range of acid soils with differing physico-chemical futures. Soil samples with varying acidity levels were collected from different locations in the acidic Black Sea Region of Türkiye. Out of the nine soil samples collected, four were obtained from regions where hazelnuts are grown, while the other five were obtained from areas dedicated to tea growth. The sorption properties of soils limed at 0%, 50%, and 100% of lime requirement and incubated for 12 months, then the Langmuir and Freundlich adsorption isotherms were determined by batch sorption technique. The results showed that increasing the soil pH resulted in an increase in Cu adsorption. Experimental results of Cu adsorption were explained with high coefficients of determination (93.44-98.98%) of the Langmuir model. In the three experimental groups with full, half, and no lime application, pH increased significantly to 3.95, 4.46, and 5.89, respectively, while the maximum adsorption obtained from Langmuir adsorption curves, Qmax1 1553, Qmax2 2205, and Qmax3 3902 mg kg-1, respectively. While the maximum adsorption in the tea plantation areas varied between 1491 and 1514 mg kg-1, the maximum adsorption in hazelnut cultivation areas varied between 777 and 3333 mg kg-1. These findings suggest that liming or other methods to increase soil pH could be effective soil management in reducing Cu mobility in acidic soils.

Wood Biomass Ash (WBA) from the Heat Production Process as a Mineral Amendment for Improving Selected Soil Properties

This research concerned the possibilities of the natural management of ash, which is a waste product obtained in the process of burning wood chips in a bio-heating plant. The basis of the research was a pot experiment, which was carried out in a greenhouse of the University of Warmia and Mazury in Olsztyn, Poland. This experiment dealt with the influence of increasing doses of wood biomass ash added to soil on selected soil properties. The soil used for the pot experiment was taken from the arable layer (0–25 cm) of the soil. It was characterized by acidic reaction, low salinity, and an average content of total carbon (TC). The test plant was corn. Soil analysis after plant harvest showed an increase in pH and a significant improvement of soil sorption properties, without causing an excessive increase in soil salinity. In addition, a significant increase in the content of available K, P, and Mg was observed, which at the highest dose of WBA reached: 121.9; 109.3, and 41.33 mg kg−1 of soil, respectively. The content of trace metals: iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), cadmium (Cd), lead (Pb), cobalt (Co), chrome (Cr), and nickel (Ni) in the soil was quite varied but did not exceed the permissible values for agricultural soils. The content of available forms of these trace metals at the highest dose of WBA was, respectively, 1004, 129.9, 8.70, 2.08, 5.54, 0.195, 1.47, 0.97, and 1.92 kg−1 of soil. The results confirmed the significant fertilizing potential of wood biomass ash.

Natural soils in OECD 222 testing — influence of soil water and soil properties on earthworm reproduction toxicity of carbendazim

Soil sorption properties can influence the bioavailability of substances and consequently the toxicity for soil organisms. Current standardised laboratory testing for the exposure assessment of pesticides to soil organisms uses OECD artificial soil that does not reflect the high variation in chemical-physical soil properties found in natural agroecosystems. According to guideline OECD 222, earthworm reproduction tests with Eisenia fetida and the pesticide carbendazim were performed in four natural soils and OECD artificial soil. By using pF 1.6, which ensures a uniformity in actual soil water availability, the control reproduction performance of E. fetida in all natural soils was at the same level as OECD artificial soil. In a principle component analysis, the variation in toxicity between the tested soils was attributable to a combination of two soil properties, namely total organic carbon content (TOC) and pH. The largest difference of 4.9-fold was found between the typical agricultural Luvisol with 1.03% TOC and pH 6.2 (EC10: 0.17 (0.12–0.21) mg a.i. kg−1 sdw, EC50: 0.36 (0.31–0.40) mg a.i. kg−1 sdw) and OECD artificial soil with 4.11% TOC and pH 5.6 (EC10: 0.84 (0.72–0.92) mg a.i. kg−1 sdw, EC50: 1.07 (0.99–1.15) mg a.i. kg−1 sdw). The use of typical agricultural soils in standardised laboratory earthworm testing was successfully established with using the measure pF for soil moisture adjustment. It provides a more application-oriented approach and could serve as a new tool to refine the environmental risk assessment at lower tier testing or in an intermediate tier based approach.

Вплив іонної сили розчину на формування підвищеної міграції 90Sr в підземних водах промислового майданчика Чорнобильської АЕС

Thermodynamic modeling of 90Sr migration was performed based on data from monitoring studies on well 4-G, which, before its liquidation in 2008, was located on the industrial site of the Chornobyl nuclear power plant. The study of the 90Sr migration forms was carried out using a set of software tools “Geochemist’s Workbench Community Edition”. In order to confirm and understand the migration processes, modeling of the spread of various complex 90Sr compounds such as SrCO3, SrHCO3, SrSO4, SrOH+ and SrNO3 + with groundwater was carried out. With the help of SpecE8, the calculation of various forms of 90Sr was performed, and the ionic strength of the groundwater solution (ISS) was also calculated. In the range of pH 9.5–12.4, there is an increase in the Sr2+ concentration in groundwater by 200–500 times to 550 Bq/l. In the same pH interval, according to thermodynamic modeling, an increase in the concentration of strontium in the form of SrOH+ and a decrease in the form of Sr2+ is observed in groundwater. At the same time, the dominance of strontium concentrations in the form of SrOH+ over Sr2+ does not occur. The reason for the sharp increase in the volume activities of 90Sr in strongly alkaline groundwater was the increase in the ISS > 5 mmol/l. An increase in the ISS of strongly alkaline groundwater leads to a decrease in the sorption properties of soils, and to the remobilization of adsorbed 90Sr back to groundwater through cation exchange. Probably, in the pH range of 9.5–12.4 and the ISS > 5 mmol/l, there is a change in the surface charge of soil particles, usually from negative to positive, in which cations cannot be sorbed, but, on the contrary, must to remobilize from the soil surface to groundwater. At the same time, pH = 9.5 is probably the point of zero charge (pzc). To assess the possibility of a relationship between the concentrations of 90Sr and ISS, a correlation analysis using the geochemical statistics method was carried out. At the same time, the correlation coefficient K = 0.87, which proves the existence of a close relationship.

Effect of Organic Nano-Materials on Heavy Metals Concentration of Wheat Plants Inoculated With Piriformospora indica Fungus and Irrigated With Wastewater of Plating Industry

Removal of heavy metals from industrial effluents is one of the most important in environmental research. This research was done to investigate the adsorption effect of multiwall carbon nanotubes (MWNTs) and nano Zn-oxide on decreasing chromium (Cr) and cadmium (Cd) concentration in wheat inoculated with Piriformospora indica (P.indica) that irrigated with wastewater of plating industry. Treatments were consist of applying MWCNs (0 and 0.5 % (W/W)) and nano Zn-oxide (0 and 1.5 % (W/W)) in the soil irrigated with the wastewater of plating industry under wheat inoculated with P.indica. This research was done as a factorial experiment in the layout of completely randomized block design in three replication After 90 days, plants were harvested and plant Cd and Cr were measured using atomic absorption spectroscopy. Using MWCNs had significant effect on increasing cation exchangeable capacity of soil. Applying 0.5 % (W/W) MWCNs in the soil irrigated with waste water significantly decreased the soil Cd concentration by 11.7%, while the plant biomass was increased by 13.4%. In addition, applying 1.5 % (W/W) nano Zn-oxide significantly decreased the negative effect of heavy metal toxicity that can be related to the role of nano Zn-oxide on increasing soil sorption properties. However, the interaction effect of Zn and Cd cannot be ignored. The results of this study showed that applying MWCNs and nano Zn-oxide has a significant effect on decreasing phytoremediation efficiency in soil irrigated with wastewater of plating industries. However, the type and the amount of heavy metals in wastewater cannot be ignored.

Effect of Nano Fe-oxide and Endophytic Fungus (P. indica) on Petroleum Hydrocarbons Degradation in an Arsenic Contaminated Soil under Barley Cultivation

Heavy metals and petroleum hydrocarbon pollution are important environmental problems. This research was conducted to evaluate the effect of nano Fe-oxide and endophytic fungus (P. indica) on petroleum hydrocarbons degradation in an arsenic and petroleum hydrocarbons contaminated soil using barley plant. Treatments consisted of the presence (E+) and the absence (E-) of P.indica fungi, soil contaminated with As in the rates of 0 (AS0), 12 (AS12) and 24 (As24) mg As /kg of soil, and application of 0 (Fe0) and 1% (Fe1) (W/W) nano Fe-oxide. The plant used in this study was the barley plant. After 7weeks, the root and shoot As concentration was measured using atomic absorption spectroscopy. The concentration of total soil petroleum hydrocarbon (TPHS) was measured using GC-mass. Application of nano Fe-oxide in soil treated with 12 and 24mg As/kg soil decreased root As concentration by 30 and 20.6%, respectively. The presence of P.indica caused a significant reduction in the shoot As concentration. With increasing shoot Fe concentration the shoot As concentration was decreased. The highest TPHS degradation was observed in non As-polluted soil that containing 1% (W/W) nano Fe-oxide in the presence of P.indica, while the lowest that was in As polluted soil (24mg As/kg soil) without applying nano Fe-oxide and in the absence of P.indica. Increasing soil sorption properties due to nano Fe-oxide application had significant effect on TPHS degradation in the presence of P.indica. However the role of soil condition on the amount of TPHS degradation cannot be ignored.

Разработка модели миграции мышьяка по почвенному профилю из накопленных отходов горно-перерабатывающей промышленности

In view of the difficult situation in the country in recent years regarding the accumulated environmental damage, including that caused by arsenic-containing waste of mining and processing industry, there is an urgent need to develop a methodology to eliminate the social and environmental consequences of this negative impact. The article presents a study of the soil sorption properties for the Svirsk municipal district that has been long subject to the arsenic waste pollution. In the course of the experiments, the sorption capacity of various soils typical of the examined territory has been defined. The study has shown that among the studied soil types, the dense scaly brownish loamy soils are distinguished as having the highest sorption capacity. The soil with the capacity of 2 to 9 m has proved to be an important geo-ecological barrier prohibiting penetration of arsenic and heavy metals into the underlying aquifers. Using the obtained data, a computer model has been developed with the purpose to predict the arsenic spread in the soil. Based on the research results, the remediation technology for the Svirsk municipal district has been developed. Using the data on various soil types’ sorption capacity and the layer thickness, it is possible to identify the territory zones that have the highest potential for self-conservation i.e. immobilization of mobile arsenic forms in the natural geochemical barrier. The developed model of arsenic migration can be used for predicting the toxicant spread in other regions contaminated with arsenic-containing waste of mining and processing industries.

Possibility of forming artificial soil based on drilling waste and sewage sludge

Land redevelopment is necessary due to the amount of a degraded area. Depositing waste on the small area of landfills is harmful for the environment. New methods of managing and utilizing waste are being sought in order to minimize the deposition of waste. In small amounts, many types of waste can be treated as a substrate or material improving physicochemical properties of soils, and hence can be used in reclamation of degraded lands. The study analysed the effect of different doses of sewage sludge (35%, 17.5%) with addition (2.5% and 5%) of drilling waste on the properties of degraded soils. The results show that created mixtures improve the sorption properties of soil. The mixtures contain the optimal the ratio of nutrient elements for growth of plants is N:P:K.

Leaching of ammonium and nitrate from Acrisol and Calcisol amended with holm oak biochar: A column study

Biochar is a carbon-rich porous material intensively studied for its agronomic benefits, such as decrease of greenhouse gases emission and nutrient losses via leaching, increased crop production and improved soil physical and chemical properties. We investigated the effect of holm oak biochar produced at 600 °C on mineral nitrogen (N) leaching from two contrasting soils (Acrisol and Calcisol). Biochar was applied at three rates (0%, 1% and 2% w/w) with (B0-F, B1-F and B2-F, respectively) and without (B0, B1 and B2, respectively) ammonium-based fertilizer. Soil columns were leached with deionized water and mineral N in leachate was monitored during ten weeks after each fertilization. Sorption behavior of biochar-amended soils was assessed in batch experiments before and after leaching. Biochar increased ammonium (NH4+-N) sorption in sandy Acrisol but had no effect on nitrate (NO3− -N) sorption. Furthermore, sorption properties of soil decreased by up to 25% during the study. In Acrisol, biochar affected NH4+-N leaching, which was increased by both doses of biochar without fertilization, but decreased by the lower biochar application rate when fertilizer was added. The leaching of NO3−-N was not affected by biochar in Acrisol. The ability of Calcisol to adsorb NH4+-N was high and was not further increased by biochar, which corresponds to no NH4+-N leaching from Calcisol regardless the biochar application rate. Moreover, biochar had no effect on NO3−-N leaching from Calcisol. Our results demonstrate that biochar effect on leaching of inorganic N forms is inconsistent, evolves in time and is highly dependent on soil properties. Alleviation of soil acidity by biochar application to Acrisol resulted in short-term stimulation organic N mineralization, which resulted in enhanced amount of NH4+-N being leached. Furthermore, the fact that biochar lost its effect on N leaching already after the second fertilizer application could cast a doubt on the efficiency of biochar application to soil in order to increase N retention and decrease N leaching.

Study on the sorption process on geological materials of long-lived radioactive isotopes 90Sr and 137Cs in model systems with the use of short-lived isotopes of 85Sr, 134Cs

The objective of this work was to determine the sorption properties of soil underneath the National Radioactive Waste Disposal facility (NRWD) in Rozan (NE Poland) for strontium (Sr) and caesium (Cs). The soil underneath the disposal was mainly sands consisted with quartz. The NRWD is a Low and Intermediate Level Wastes type facility. The procedure was new for our laboratory and turned out to be simple and effective. Sorption process analyses were carried out according to pH, ionic strength, time changes and tracer concentration in the solution. We also determined the Langmuir adsorption isotherms.

Impact of alkaline alterations to a Brazilian soil on cesium retention under low temperature conditions

To be used as backfilling materials in radioactive waste disposal facilities, a natural material must have a suitable permeability, mechanical properties and a high sorption capacity for radionuclides. Also important when considering a material as a backfill is the effect of its interaction with the alkaline solution generated from concrete degradation. This solution promotes mineralogical alterations that result in significant changes in the material key properties influencing its performance as a safety component of the repository. This paper presents results of an investigation on the effect of alkaline interaction under a low temperature on cesium retention properties of a local soil being considered suitable as a backfill for the Brazilian near surface disposal facility. A sample of the Brazilian soil was mixed with an alkaline solution, simulating the pore water leached in the first stage of cement degradation, during 1, 7, 14 and 28 days. The experiments were conducted under low temperature (25 °C) aiming to evaluate similar conditions found on a low and intermediate level radioactive waste disposal installation. A non-classical isotherm sorption model was fitted to sorption data obtained from batch experiments, for unaltered and altered samples, providing parameters that allowed us to assess the effect of the interaction on material quality as Cs sorbent. The sorption parameters obtained from the data-fitted isotherm were used then to estimate the corresponding retardation factor (R). Alkaline interaction significantly modified the soil sorption properties for Cs. The parameter Q, related to the maximum sorption capacity, as well as the affinity parameter (K) and the retardation coefficients became significantly smaller (about 1000 times for the R coefficient) after pretreatment with the simulated alkaline solutions. Moreover, the increase in n-values, which is related with the energy distribution width and heterogeneity of surface site energies, demonstrated that the adsorbent surface became more homogenous as a consequence of the alkaline alteration. Together these results suggest that cementitious leachate has a profound effect on Cs retention and should be accounted for estimating radionuclide retention in radioactive waste disposal systems containing cementitious materials.

The studies of the sorption properties of soils at the base of the ash storage of the projected power station on Sakhalin Island

The soil sorption properties were determined for the base of ash storage at a proposed power station on Sakhalin Island. The analyses of aqueous extracts of the coal ashes that are intended for use at the station resulted in the identification of potential pollutant elements that might be transferred with the infiltrate of atmospheric precipitation. The composition of the infiltrate-modeling solution was selected based on the data. The sorption capacity of the covering soil by identified pollutants was evaluated at static and dynamic conditions, along with the degree of potential desorption of these pollutants.

Study of sorption properties of soils at the base of ash storage site of proposed SakhalinGRES-2

Sorption properties of the soil layer at the base of the ash disposal site of the Sakhalin GRES-2 at the design stage of the facility were determined. Water extracts of the ash from the coal that will be used at the facility were analyzed to identify the potential elements-pollutants able to migrate with atmospheric precipitation through the soil. The model solution was developed based on these data. The soil sorption capacity in relation to the identified pollutants and the level of their potential desorption have been determined in static and dynamic conditions.

The Influence of Exogenic Organic Matter on Selected Chemical And Physicochemical Properties of Soil

Organic matter plays an important role in stability and fluxes of trace greenhouse gases between land surface and atmosphere. A steady decline of soil organic matter in Poland is observed, therefore the pending problem and new challenge is to increase its level, particularly in sandy soils. In the last decades a growing interest in various sources of organic matter, for example brown coal, its derivatives and composts – has been observed. Organic matter applied in the form of the brown coal (Rekulter preparation), brown coal, peat, and farmyard manure resulted in changes of selected chemical and physicochemical properties of the soil. One year after application of organic matter, the highest increase in soil reaction pH was found in the case of Rekulter, and the same behaviour was observed seven years after its application. Remarkable influence on sorption properties of soil was in the case of brown coal and brown coal preparation. Exogenic organic matter increased the TOC and the total N, occurring mainly in the case of the Rekulter. The highest value of the TOC to Nt ratio equalling 20 obtained for the soil sample with the Rekulter was due to the highest carbon content in this object. It was found that after introduction of this organic matter into the soil, the value of the C:N ratio increased as compared to control soil ones.

Analysis of the sorption properties of different soils using water vapour adsorption and potentiometric titration methods

Abstract Parameters of specific surface area as well as surface charge were used to determine and compare sorption properties of soils with different physicochemical characteristics. The gravimetric method was used to obtain water vapour isotherms and then specific surface areas, whereas surface charge was estimated from potentiometric titration curves. The specific surface area varied from 12.55 to 132.69 m2 g−1 for Haplic Cambisol and Mollic Gleysol soil, respectively, and generally decreased with pH (R=0.835; α = 0.05) and when bulk density (R=−0.736; α = 0.05) as well as ash content (R=−0.751; α = 0.05) increased. In the case of surface charge, the values ranged from 63.00 to 844.67 μmol g−1 Haplic Fluvisol and Mollic Gleysol, respecively. Organic matter gave significant contributions to the specific surface area and cation exchange capacity due to the large surface area and numerous surface functional groups, containing adsorption sites for water vapour molecules and for ions. The values of cation exchange capacity and specific surface area correlated linearly at the level of R=0.985; α = 0.05.

ACIDITY AND SORPTION PROPERTIES OF ZINC-CONTAMINATED SOIL FOLLOWING THE APPLICATION OF NEUTRALISING SUBSTANCES

Soil plays the most important role in the cycling of elements in the terrestrial environment. Contamination of soil with heavy metals have effect on all soil organism and plants. For this reason, studies have been carried out to assess the possibility of neutralising the effect of zinc (0, 150, 300, 600 and 1200 mg Zn∙kg-1 of soil) on soil properties by applying neutralising substances (compost, bentonite and zeolite). Soil acidity and sorption properties depended on zinc contamination and on the type of neutralising substances added. In the series without an addition of neutralising substances, increasing zinc soil contamination resulted in a decrease in total exchangeable bases, in cation exchange capacity and in the saturation degree of the degree of base saturation, and an increase in soil hydrolytic acidity. An addition of bentonite to zinc-contaminated soil had the most advantageous effect of all the additions of neutralising substances on the tested soil properties. It resulted in an increase in soil pH, in total exchangeable bases, in cation exchange capacity, in the degree of base saturation and simultaneously decreased soil hydrolytic acidity compared to the series without additions. Adding zeolite and compost to soil had a small and usually insignificant effect on soil acidity and soil sorption properties.

About the Use of Enzymatic Activity in Environmental Regulation in the Evaluation of the Oil-Contaminated Soils

There was considered the possibility of use the catalase activity as marker pattern and intensity of biological processes in soils in terms of oil pollution. There was showed that dependence of catalase activity on concentration of oil products is dual in nature, testifying the good information content of this indicator and its potential use in evaluating og oil-contaminated soils and environmental regulation. There was revealed a significant change in the activity of catalase (p<0.05) in spodozols with oil contamination level of 10 g/kg, in peat-spodozols humus-illuvial – 20 g/kg, the differences in the set values due to sorption properties of soils. When establishing the permissible content of oil products in spodozols applied non-linear regression model described by a logistic curve.

Experimental investigation on the soil sorption properties and hydrophobicity of polymethoxylated, polyhydroxylated diphenyl ethers and methoxylated-, hydroxylated-polychlorinated diphenyl ethers

In the present study, twenty-six types of polymethoxylated diphenyl ethers (PMeODEs), twenty types of polyhydroxylated diphenyl ethers (PHODEs), seven types of methoxylated-polychlorinated diphenyl ethers (MeO-PCDEs) and seven types of hydroxylated-polychlorinated diphenyl ethers (HO-PCDEs) were synthesized. The logKow and logKoc values of all of the synthesized compounds were then determined using HPLC. The soil sorption properties of five types of selected substituted diphenyl ethers (DEs) were investigated. Sorption behavior studies suggested that rapid sorption played a primary role in the sorption process of the selected DEs and their sorption isotherms were fitted the Freundlich logarithmic model. For PMeODEs and PHODEs, with the increase in the number of substituents, both logKow and logKoc values exhibited linearly decreasing trends. Unlike PMeODEs and PHODEs, both logKow and logKoc values of MeO/HO-PCDEs were decreased linearly with the increasing number of chlorine atoms. The reason maybe that both methoxy and hydroxyl are hydrophilic groups, whereas the chlorine atom is hydrophobic group. Linear relationships were observed for the logKow and logKoc of all studied DEs. Moreover, the logKow of PMeODEs, PHODEs, MeO- and HO-PCDEs and their corresponding PCDEs showed good linearity.

Mineral fertilisation as a factor determining selected sorption properties of soil against the activityof phosphatases

The paper presents the contents of phosphorus and potassium available in soil, soil sorption properties against the activity of alkaline and acid phosphatase. The fertilisation applied involved P, K, Mg, Ca and S: (P K Mg Ca S), (K Mg Ca S), (P Mg Ca S), (P K Ca S), (P K Mg S), (P K Mg Ca) as well as nitrogen fertilisation at the following rates: 0, 50, 100, 150, 200, 250 kg N/ha. The application of high nitrogen rates with no liming applied resulted in an unfavourable increase in hydrolytic acidity and a decrease in the total bases, cation exchange capacity as well as the sorption complex saturation with bases. According to the criteria provided in PN-R-04023, the soil investigated can be classified as the 3<sup>rd</sup> class with an average available phosphorus (P<sub>E-R</sub>). The analysis of Luvisol salinity demonstrated that the unbalanced mineral fertilisation applied did not trigger any chemical degradation. Significant values of the coefficients of correlation were recorded between the activity of alkaline and acid phosphatase and the parameters investigated (hydrolytic acidity, total exchangeable, base stauration, P<sub>E-R</sub>). The calculated enzymatic index of soil pH (AlP/AcP) ranged from 0.11 to 0.72.

The Use of Phosphorus Sorption Parameters in the Monitoring of Potential Emissions of this Component from the Arable Lands

Abstract The study assesses the usefulness of different methods of determining the sorption properties of soils in relation to phosphorus in the agricultural soils from Central Poland in terms of the risk of environmental pollution posed by this component. As a reference parameter necessary to achieve the study.s objective, the sorption capacity of soils for phosphorus determined on the basis of the Langmuir model was used. The results of the tests were used to calculate the degrees of soil saturation with phosphorus: PE-R/Smax (Psat1); PE-R/PSI36 (Psat2), PM3/AlM3 + FeM3 (Psat3); Pox/Alox+Feox (Psat4); PE-R/AlM3+FeM3 (Psat5); PE-R/ Alox+Feox (Psat6). The usefulness of these indicators for assessing the risk of phosphorus emissions from agricultural land was determined on the basis of the coefficients of their correlation with the amount of active phosphorus in the soil. The study proved the usefulness of the Mehlich-3 and acid ammonium oxalate solutions for assessing the sorption capacity and the degree of saturation with phosphorus of typical Polish agricultural soils. For identifying the risk of phosphorus leaching from the soils, the parameter that specifies the extent of soil saturation with phosphorus as determined by the Egner-Riehm test and the sorption index (PSI) obtained by equilibrating the soils with a solution containing 36 mg P dm.3 at the soil-to-solution ratio of 1:10 (Psat2) were also found useful.