Christos Tsadilas

A review of the distribution coefficients of trace elements in soils: influence of sorption system, element characteristics, and soil colloidal properties.

Knowledge about the behavior and reactions of separate soil components with trace elements (TEs) and their distribution coefficients (Kds) in soils is a key issue in assessing the mobility and retention of TEs. Thus, the fate of TEs and the toxic risk they pose depend crucially on their Kd in soil. This article reviews the Kd of TEs in soils as affected by the sorption system, element characteristics, and soil colloidal properties. The sorption mechanism, determining factors, favorable conditions, and competitive ions on the sorption and Kd of TEs are also discussed here. This review demonstrates that the Kd value of TEs does not only depend on inorganic and organic soil constituents, but also on the nature and characteristics of the elements involved as well as on their competition for sorption sites. The Kd value of TEs is mainly affected by individual or competitive sorption systems. Generally, the sorption in competitive systems is lower than in mono-metal sorption systems. More strongly sorbed elements, such as Pb and Cu, are less affected by competition than mobile elements, such as Cd, Ni, and Zn. The sorption preference exhibited by soils for elements over others may be due to: (i) the hydrolysis constant, (ii) the atomic weight, (iii) the ionic radius, and subsequently the hydrated radius, and (iv) its Misono softness value. Moreover, element concentrations in the test solution mainly affect the Kd values. Mostly, values of Kd decrease as the concentration of the included cation increases in the test solution. Additionally, the Kd of TEs is controlled by the sorption characteristics of soils, such as pH, clay minerals, soil organic matter, Fe and Mn oxides, and calcium carbonate. However, more research is required to verify the practical utilization of studying Kd of TEs in soils as a reliable indicator for assessing the remediation process of toxic metals in soils and waters.

Lead(II) retention by Alfisol and clinoptilolite: cation balance and pH effect

Lead (Pb 2+ ) sorption by Alfisol and zeolite was studied at pH 3, 4, and 5 to find the relationship between the amounts of Pb retained and ions displaced from the soil into the solution. In Alfisol Pb sorption was accompanied by the increase in contents of both Ca 2+ and H + constituting about 2/3 and 1/3 of the total amount of displaced cations, respectively. Increase in pH enhanced sorption of Pb. Hystersis of lead adsorption was observed in Alfisol. Clinoptilolite zeolite sorbed 20–30 times more Pb than the soil. Lead sorption by zeolite was not influenced by pH and was accompanied by the increase of Ca 2+ ,N a + , and K + contents in solution, whereas amounts of displaced H + were negligible. The research indicates that Pb retention both by Alfisol and zeolite can be viewed as the result of ion exchange reaction with strong (soil) or very strong (zeolite) specific binding of Pb. Application of zeolite in some instances may appear the most efficient treatment for reclamation of lead-contaminated soils due to its high ability to retain Pb in a wide range of pH. D 2003 Elsevier Science B.V. All rights reserved.

Influence of fly ash application on copper and zinc sorption by acidic soil amended with sewage sludge.

Fly ash (FA) and sewage sludge (SS) are usually used in agriculture as soil amendments, creating a risk of heavy‐metal pollution. However, simultaneous application of these wastes may reduce the mobility of heavy metals in soils. This study investigates the influence of fly ash application on copper (Cu) and zinc (Zn) sorption by an acidic soil amended with SS. An adsorption experiment of Cu and Zn was carried out in a Typic Haploxeralf from Greece amended with various doses of fly ash [0.25% (FA1) and 0.5% (FA2)]; sewage sludge [0.28% (SS1) and 0.56% (SS2)]; and fly ash plus sewage sludge [(FA1 + SS1) and (FA1 + SS2)] and incubated for 1 month under field capacity conditions. Furthermore, a sample without any amendment was incubated as a control for comparison. The Freundlich equation was used to describe adsorption of Cu and Zn. Distribution coefficient (K d), which represents sorption affinity of metals for the solid phase, was obtained for all the treatments applied. Data showed that Cu K d values were obviously higher than Zn values in all the treatments applied. Distribution coefficients values for FA2 treatment were about 10 and 7 times greater than the control for Zn and Cu, respectively. Simultaneous application of FA and SS caused K d increases of 4.2 and 3.5 times more than treatment that received only SS for Zn and Cu, respectively. Distribution coefficient values of Zn and Cu were significantly correlated with soil pH. These results confirm that alkaline FA can be used as an effective amendment for remediation of Cu‐ and Zn‐polluted acidic and SS‐amended soils.

Phosphorus Sorption and Availability to Canola Grown in an Alfisol Amended with Various Soil Amendments

The aim of this study was to examine the influence of various soil amendments on sorption and availability of phosphorus (P) in a biosolid-amended Alfisol planted with canola. For this purpose a greenhouse pot experiment was established in an acidic Greek Alfisol amended once with sewage sludge (300 t ha−1) 13 years ago. Five kg from this soil was thoroughly mixed with 0 or 50 g of zeolite (Z), coal fly ash (FA), sugar beet factory lime (SBFL), and compost from olive oil–processing wastes (OW) and cultivated with canola (Brassica napus). Additionally, a non-biosolid-amended soil from an adjacent field was used as control. Two months after planting, soil and plant samples were selected and analyzed for available and total P. Phosphorus sorption isotherms were prepared on soil samples after plants were harvested, and adjusted to the Freundlich equation. Phosphorus distribution coefficient (K d) values were obtained by the same batch equilibrium experiments. Results showed that 13 years after application of high-dose biosolids, soil pH increased from 5.19 to 6.92, canola biomass yield increased from 1.96 to 5.3 g pot−1, Olsen P increased from 25.5 to 57.7 mg kg−1, and plant tissue P concentration increased from 1162 to 2881 mg kg−1. Application of FA, Z, SBFL, and OW to the biosolid-amended soils increased soil pH from 6.92 to 8.05, 7.07, 7.72, and 7.19, canola biomass yield from 5.3 to 8.6, 7.5, 7.6, and 5.4 g pot−1, and Olsen P from 57.7 to 110.5, 61.2, 80.5, and 64.5 mg kg−1respectively. Application of Z, SBFL, and OW to the biosolid-amended soil increased plant tissue P from 2881 to 3048, 3320, and 3523 mg kg−1, respectively, whereas FA application decreased it to 2696 mg kg−1. Application of the high dose of biosolids to the acidic Alfisol decreased P_K d from 23.3 to 12.9 L kg−1. Application of FA, Z, and SBFL to the biosolid-amended soil increased P_K d from 12.9 to 23.19, 13.83, and 14.48 L kg−1, respectively, whereas OW application decreased it to 12.82 L kg−1.Values of Kd decreased as the concentration of the added P increased in the test solution in the case of non-biosolid-amended soil and fly ash treatment but it relatively increased as the concentration of the added P increased in the test solution in the biosolid-amended soil and Z, SBFL, and OW treatments.

Influence of liming and nitrogen forms on boron uptake by tobacco

Abstract The purpose of this study was to investigate the influence of soil liming and fertilizer nitrogen forms on the availability of soil B and its uptake by tobacco plant. A field experiment was conducted on an acid Typic Haploxeralf soil, located in Pieria, Northern Greece. The experimental design was factorial 3×3 with four replications. The first factor included three rates of lime (0, 4000, and 8000 kg/ha limestone) and the second three combinations of nitrogen forms i.e. a) NO3-N 100%, b) NH4-N 100%, c) NO3-N 50% plus NH4-N 50%. Tobacco harvesting was done in four cuttings. Composite leaf samples were selected and analysed for B, Ca, and K. At the end of the experiment composite soil samples were also collected from each experimental plot and were analysed for pH, exchangeable cations and available B using the hot 0.01M CaCl2 extraction procedure. The results showed that soil liming increased soil pH proportionally to the amount of limestone applied. Fertilizer N forms did not significantly affect soil pH. Soil liming significantly decreased available B, which was strongly correlated with soil pH negatively. Boron concentration in tobacco leaves was significantly decreased up to deficiency levels being strongly correlated with available B positively but negatively with soil pH. Ca/B ratio was significantly increased indicating B deficiency. This ratio was strongly correlated with soil pH and exchangeable Ca. Fertilizer N forms did not cause any significant influence on B uptake. The latter was also true for potassium.

Utilization of Biosolids in Production of Bioenergy Crops I: Impact of Application Rate on Canola Biomass, Soil Properties, and Nutrient Availability

Amendment of agricultural soils with municipal sewage sludge (SS) or biosolids may provide a valuable source of plant nutrients and organic matter. Utilization of SS in cultivation of oil- and biofuel-producing crops such as canola (Barassica napus) has not been adequately studied. The aim of this study was to compare the influence of biosolid application rates on biomass production of canola and on soil properties and nutrient availability measured both by conventional methods and a new technique involving plant root simulators (PRS probes). For this purpose, a greenhouse pot experiment was established in a Typic Xerfluvent (5 kg) from central Greece amended with various rates of SS [0 Mg ha−1 (C) 20 Mg ha−1 (SS1), 50 Mg ha−1 (SS2), and 100 Mg ha−1 (SS3)] and cultivated with canola. After a 2-month planting period, the whole plants and soils were removed from the pots. One kg of the soils was selected for analyses, and the rest of the soil was cultivated again for 2 more months with the same crop. Bioavailability of phosphorus (P) and potassium (K) was measured using the conventional methods (Olsen and ammonium acetate method respectively) as well as by PRS probes. Results showed that application of SS significantly increased canola biomass only in the treatment SS1 compared to the control in the first planting period. However, in the second period, SS application significantly increased canola biomass in the treatments SS2 and SS3 compared to the control and SS1. Soil pH decreased significantly from 7.9 in the control treatment to 6.9 in the treatment SS3. Furthermore, soil organic matter, nitrate nitrogen, and hot water–extractable boron were significantly increased with increasing SS application rate. Olsen P increased significantly with SS application in both planting periods but its increase was greater in the second planting period compared to the first one. Phosphorus-supplyrate (PSR) as assessed by the PRS probes increased significantly with SS application rate in both planting periods but it decreased significantly in the second planting period as compared to the first one. Plant tissue concentration P showed a trend similar to P supply rate (PSR). A strong relationship was recorded between PSR and Olsen P while plant tissues P concentration was strongly correlated with PSR and Olsen P (R2 0.93*** and 0.87*** respectively), indicating that probe method estimates better bioavailability of P to the grown plants compared to the Olsen method. Application of SS decreased significantly available K and potassium-supply rate (KSR) compared to the control, especially in the second planting period. Potassium-supplying rate decreased significantly in the second period compared to the first one. No relationships were recorded among KSR, ammonium acetate K, and plant tissue K concentration.

Land-Use Effect on Selected Soil Quality Parameters

Land use is a key factor that affects soil quality. The purpose of the present study was to investigate changes of selected soil chemical properties related to soil function under different land uses. Five experimental sites arranged in a complete randomized blocks located within the Kalloni watershed (Lesvos Island, Greece) corresponding to different land uses (Pinus brutia forest, brushwood pasture, rain-fed olive grove, wheat, and maize) were compared for soil pH, electrical conductivity (EC), total nitrogen (N), nitrate N (NO3-N), Olsen phosphorus (P), and organic matter. Soil nitrate and P concentration were in the order corn > wheat > olive > pasture > forest. Soil EC and NO3-N showed significant within-year variability only in the corn and wheat systems. Corn and wheat had the lowest soil organic-matter content followed the order forest > pasture > olive grove = wheat = corn. However, total N did not significantly differ among land uses.

Distribution of total and ammonium bicarbonate-DTPA-extractable soil vanadium from Greece and Egypt and their correlation to soil properties.

Vanadium (V) is a trace element involved in soil pollution, originating from either soil parent material or anthropogenic sources. The aim of this study was to investigate the distribution of total and ammonium bicarbonate-DTPA-extractable (AB-DTPA) V in soil profiles of representative Greek and Egyptian soils and their relationships to soil properties. Twenty-one soil profiles from Egypt and Greece (representing the main soil orders, that is, Entisols (developed on fluvial, lacustrine, and marine deposits) and Aridisols for Egyptian soils and to the soil orders Entisols, Alfisols, Inceptisols, Vertisols, Mollisols, and Histosols for Greek soils) were sampled and analyzed for total and AB-DTPA-extractable V, and the relationship of V levels to soil properties were examined. Total V concentrations ranged from 23 mg kg−1 in the marine deposits to 179 mg kg−1 in the lacustrine deposits. Total V levels significantly positively correlated to clay and silt content, cation exchange capacity, and free iron and manganese oxides and were negatively correlated to sand, organic matter, and calcium carbonate content. The AB-DTPA-extractable V varied from 0.55 mg kg−1 in the Greek Entisol to 4.4 mg kg-1 in the Egyptian lacustrine deposits and were significantly positively correlated with total V concentration, soil pH, clay and silt content, and cation exchange capacity (positively) and negatively correlated with sand content. Distribution of total and AB-DTPA-extractable V related mainly to particle size distribution, sesquioxides content, and soil pH. These results suggest that V could be a concern for many of the soils studied because in a large number of samples, V concentration values exceeded the international regulatory standards for remediation.

Evaluation of Methods for Determination of Soil Boron Available to Apple Trees

Abstract Soil boron (B) available to plants can be determined by using several methods. This study evaluated the efficiency of hot water extraction, saturation paste, resin, mannitol, and hydrochloric acid methods for determination of soil B available to two apple tree varieties (Malus domestica, var. golden and black). Soil samples from 26 sites where the golden and black apple varieties were growing in northern Greece were collected and analyzed for B by these five procedures. Boron concentration in apple tree leaves from these sites was also determined. Hot water extractable boron (HwsB) was strongly correlated with B extracted by mannitol (Man‐B) and HCl (HCl‐B). Soil B extracted by all the methods was significantly correlated with B concentration in apple tree leaves of both varieties, except golden in the case of the saturation paste method. Boron extracted with use of the resin method correlated best with leaf B for both varieties followed by the mannitol and HCl methods. Resin‐extractable soil B concentrations causing deficiency and toxicity were 1.20 and 5.19 mg kg−1 soil, respectively. For the other methods, soil B concentrations corresponding to B toxicity in these apple varieties ranged from 4.0 to 6.0 mg B kg−1 soil.

Utilization of Biosolids in Production of Bioenergy Crops II: Impact of Application Rate on Bioavailability and Uptake of Trace Elements by Canola

Amendment of agricultural soils with municipal sewage sludge (SS) provides a valuable source of plant nutrients and organic matter but it may create a risk of trace-element pollution of the environment. Utilization of SS in cultivation of oil- and biofuel-producing crops such as canola (Brassica napus) may be useful for safe management of biosolids. The aim of this study was to examine the influence of SS application rate on bioavailability and phytoextraction of trace elements by canola. To achieve this goal, a greenhouse pot experiment was established in a Typic Xerfluvent from Greece amended with various rates of sewage sludge: 20 Mg ha−1 (SS1), 50 Mg ha−1 (SS2), and 100 Mg ha−1 (SS3). Furthermore, a soil sample without any amendment was cultivated and used as a control (C). After a planting period of 2 months, the whole plants and soils were removed from the pots. One kg from the soils was selected for analyses and the rest of the soil was cultivated again for 2 more months with the same crop. Soil samples were analyzed for total and available forms of trace elements [iron (Fe), manganese (Mn), copper (Cu), zinc (Zn), nickel (Ni), lead (Pb), and cadmium (Cd)] and the same elements were measured in plant tissue. The results showed that increasing SS application rate increased significantly the total amounts of all the studied trace elements compared to the control except for Fe and Ni. However, the total concentrations of all the studied elements were less than the critical concentrations in soils. Diethylenetriaminepentaacetic acid (DTPA)–extractable element concentrations increased significantly with increasing the biosolid application rate, especially in the case of SS3. However, no significant differences were recorded between control and SS1 for Fe, Mn, Pb, Ni, and Cd. Plant tissue element concentrations for all elements except for Fe increased significantly compared to the control with increasing sewage sludge application rate, especially with SS3, whereas no significant differences were found between the control and SS1 in the cases of Cu and Pb. Iron showed the opposite trend, where it decreased significantly with increasing SS rate. The ability of canola in phytoextraction of the studied elements was measured by bioconcentration ratios (BCR) (plant tissues concentration / DTPA-extractable elements). Values of BCR differed widely between the elements. Iron and Zn BCR values decreased significantly with increasing the SS application rate in both planting periods. The BCR values of Cd, Cu, Mn, Ni, and Pb increased in the SS-treated soil compared to the control with a relative increase in SS1 and SS2 treatments compared to SS3. Data from this result convinced us that there is no risk from utilization of biosolids in production of noneaten plants like canola. The recommended rate was 20 Mg SS ha−1.