N. Barbayiannis

Influence of sewage sludge application on soil properties and on the distribution and availability of heavy metal fractions

Abstract The influence of sewage sludge application on some soil properties and on the growth of wheat and corn plants were studied with pot experiments. The distribution of heavy metals among the various soil fractions and their availability to plants were also investigated in relation to soil pH. The results showed that sewage sludge application significantly ifluenced pH, organic matter content, electrical conductivity and available phosphorus. Soil pH increased and tended to hold steady near neutrality while organic matter content, electrical conductivity and available phosphorus (P) increased. For the heavy metals investigated, only total copper (Cu) and zinc (Zn) increased but were below the limits set by the EC. A significant increase was observed in the concentrations of cadmium (Cd), nickel (Ni), Cu, and Zn extracted by DTPA while iron (Fe) and manganese (Mn) were reduced showing a strong relationship to soil pH. For the metals sequentially extracted it was observed that chromium (Cr), Ni, Cu, an...

Plant Species Abundance and Tissue Concentrations of Limiting Nutrients in Low-Nutrient Grasslands: A Test of Competition Theory

1 A 3-year study tested the hypothesis that proportions of plant species are negatively related to species concentrations of limiting nutrients using a moderately acid lowland grassland site in Northern Greece, where growth was limited by soil moisture, N and P. 2 Species proportions were assessed both by a cumulative measure (above-ground biomass duration for the whole growth period) and by yield at the peak of aboveground biomass of the community. Weighted N, P and K concentrations of species for the whole growth period were calculated by dividing above-ground N or P or K content duration by above-ground biomass duration. 3 Measurements during one growth period (seven samplings from mid March to mid June in 1991) showed that biomass was higher in roots than in shoots for most species examined. For total grasses and Rumex acetosella total N and P were higher in roots than in the shoot for the whole growth period. The dicot species Cichorium intybus, Hypochoeris radicata and Plantago lanceolata contained more N and P in shoots than in roots after mid April. 4 Weighted N, P and K concentrations of shoots were positively related to their respective concentrations of whole plants. 5 Addition of either N or P increased community productivity and changed species composition, especially in years when soil moisture was adequate. 6 Proportions of species were negatively related to weighted N concentrations of species. 7 Species with higher than average N or P concentrations showed the greatest relative increases when soil was enriched with N or P, respectively. 8 These results seem to be consistent with the regulation of species abundance by competition-driven nutrient depletion.

Shoot Sr concentrations in relation to shoot Ca concentrations and to soil properties

This work was aimed to investigate whether shoot Sr concentrations of plant species are related to respective Ca concentrations and to soil properties and to compare the Sr-Ca observed ratios (OR), defined as the quotient of the ratios Sr/Ca in shoots and in the soil solution or in the extractable form, among species and soils. Ten pasture plant species were grown in pots (1-L volume) filled with eight soils differing in the various physicochemical characteristics. Each pot received 50 mg Sr except those of the soil with the highest cation exchange capacity (C.E.C.) that received 100 mg Sr per pot. For each soil, shoot Sr concentrations of species were linearly and positively related with the respective Ca concentrations. C.E.C, organic matter content and Ca in the soil solution or in the extractable form were the only soil properties that were related, all negatively, with shoot Sr concentrations. The ratio of extractable Sr and Ca was positively and linearly related with the ratio of Sr and Ca. in the soil solution. OR was affected by both species and soils. Most of OR values of all species in all soils ranged between 0.8 and 1.5, except for the grass Agrostis capillaris which had the highest values for most of soils. This indicates that Agrostis capillaris compared to other species, takes up proportionally more Sr than Ca.

Caesium and strontium uptake by two pasture plant species grown in organic and inorganic soils

Caesium (300 mg per pot) or strontium (190 mg per pot) were applied to pots, containing either 1200 g of inorganic or 560 g of organic soil 2, 1 and 0 months before sowing with either Lolium perenne or Trifolium repens. For inorganic soil only and the addition of Cs and Sr at the time of sowing, three levels of K (0, 83 and 166 mg per pot) or Ca (0, 100 and 200 mg per pot) were applied. Changes of extractable Cs were monitored with time in unsown pots. Extractable Cs decreased with time, especially in the inorganic soil. In shoots, harvested 5 months after sowing Cs and Sr concentrations were higher in Trifolium than in Lolium with a trend for lower concentrations when Cs or Sr was applied earlier. Concentrations of Cs were higher in organic than in inorganic soil. The reverse was evident for Sr concentrations. Addition of K tended to decrease and that of Ca to increase shoot Cs and Sr concentrations, respectively.

Influence of Electrolyte Concentration, Sodium Adsorption Ratio, and Mechanical Disturbance on Dispersed Clay Particle Size and Critical Flocculation Concentration in Alfisols

Abstract Clay dispersion affects both soil productivity and environmental quality through its effect on structure degradation. The effect of solution concentration (C), sodium adsorption ratio (SAR), and mechanical disturbance on clay dispersion, particle size of dispersed clay and critical flocculation concentration (CFC) was investigated in four Greek Alfisols equilibrated with NaCl/CaCl2 solutions of different C (= 5, 10, 50, and 100 mmol/L) and SAR [= 0, 5, 10, 20, and 40 (mmol/L)1/2]. Suspensions of equilibrated soil samples in solutions or in deionized water received a minimum (30 s) or a prolonged (16 h) shaking. After shaking, the dispersed clay fractions <2 and <1 µm were determined by measuring the optical density of the suspensions. It was found that both clay dispersion and CFC were increased with SAR. Relative dispersed clay of any size obtained in deionized water was always higher than in any NaCl/CaCl2 solution. Prolonged shaking resulted in much higher relative dispersed clay of any size, in greater CFC and in lower coarse (1–2 µm) to fine (<1 µm) clay ratio than minimum shaking. Relative dispersed coarse clay was always higher (p < 0.05) than relative dispersed fine clay. The coarse clay fraction displayed higher CFC than the fine clay fraction. The influence of clay content and mineralogy, organic matter, Fe2O3, pH, and mechanical disturbance on the differences in clay dispersion found between the soils used is discussed. In order to avoid clay dispersion in soils containing large-sized clay particles and/or receive intensive mechanical disturbance, it is suggested to keep the soil solution at a higher concentration.

Mineral, chemical and radiological investigation of a black sand at Touzla Cape, near Thessaloniki, Greece

A black-sand formation located at Touzla Cape, near Thessaloniki city, Greece, was investigated using optical microscopy, powder-XRD, SEM-EDS, INAA and in-situ Γ-ray spectrometry. This black sand is mainly composed of ilmenite, magnetite, garnet, zircon and rutile. Also present, in minor or trace amounts, are quartz, sphene, pyroxenes, sillimanite, feldspars, biotite, haematite, tourmaline, chromite, niobian-rutile and pyrrhotite. Niobian-rutile and pyrrhotite were found as inclusions in ilmenite and magnetite respectively. The radioactivity measurements indicated contributions of the uranium and thorium radioactive series and of 40K and 137Cs, and the maximum value of the total absorbed dose rate in air was found to be 62, 172, 8 and 2 nGy h-1 respectively. The main radioactivity of the uranium and thorium series is attributed to the fractions of zircon (304 µg Th g-1 and 157 µg U g-1), of ilmenite (89 µg Th g-1) and to a lesser extent to the fraction of garnet (5 µg Th g-1). The zircon fraction also contained 5076 µg Hf g-1. Some minerals and elements (Ti, Zr, Hf, Th, U) contained in the black sand could be of potential economic value. The high proportions of monomineralic grains along with the variations observed in mineral phases, in colour, in sphericity, in roundness, in grain size, in composition and in mineral inclusions, imply that the minerals and grains were subjected to several cycles of weathering and sedimentation, as well as being derived from multiple source rocks and areas.

Transfer factors for Sr as influenced by species Ca uptake and soil Ca availability

Strontium (Sr) and calcium (Ca) concentrations were studied in different plant species grown in five soil treatments. For either shoots or roots, a positive linear relationship was found between Sr and Ca concentrations in different plant species grown in the same soil treatment. Strontium and calcium concentrations of different species were related to the soil selectivity coefficient for Sr and Ca, defined as the ratio of CH3COONH4-extractable Sr and Ca to the ratio of Sr and Ca in the soil solution. For the species used in all soils, transfer factors (TF) for Sr, defined as the ratios of the Sr amount per g of dry plant material and the Sr amount per g of dry soil, were negatively correlated with extractable Ca of the soil. Transfer factors for Sr varied greatly among species or between roots and shoots. This variation of transfer factor was reduced when transfer factor values were divided by the shoot or root Ca concentration of each species. The proposed index TF for Sr per Ca concentration could be used to compare various soils according to their ability to supply plants with Sr when different plant species are grown in these soils.

Strontium Absorption by Two Trifolium Species as Influenced by Soil Characteristics and Liming

Strontium absorption by plants is specific to individual species and also depends on the underlying soil properties. The purpose ofthis study was to evaluate the effect of certain soil characteristics and liming on Sr absorption by twoTrifolium species. One-liter volume of two inorganic and three organic soilswere treated with a combination of three CaCO3 levels, 0, 3.6 and 7.2 g, × two Sr levels, 50 and 100 mg, (treatments) in four replications. Trifolium repens L. was grown in thetreated soils, in pots, harvested twice, and Sr in theabove-ground biomass of each harvest and soil exchangeable Caof each treatment were determined. The experiment was repeatedwith Trifolium subterraneum L., harvested once. For bothspecies, Sr transfer factor (T.F.) values of the varioustreatments were calculated. Shoot Sr concentrations weresignificantly affected by soil characteristics and Sr additionrates and were greater in T. repens. In all cases, theSr concentrations of plants grown in the organic soils, whichwere characterized by higher exchangeable Ca and cationexchange capacity (C.E.C.) values, were lower than those ofplants grown in the inorganic soils. Among the organic soils,Sr concentrations of the plants grown in the soil with thehighest values of C.E.C., organic matter and exchangeable Cawere the lowest. Liming decreased significantly the Srconcentrations in T. repens and T. subterraneumgrown in the two acid soils, while the pH and exchangeable Cawere increased. Shoot Sr concentration (log scale) wassignificantly, negatively correlated with soil exchangeable Ca. Strontium T.F. values were quite similar between the two Sr application rates and were affected by the same soil characteristics.

Physicochemical and Mineralogical Properties of Red Mediterranean Soils from Greece

Abstract Soils in regions with Mediterranean climate usually have distinct features that determine their quality and productivity. The objective of this investigation was the characterization of a number of red Mediterranean soils from Greece and their properties in relation to their development and the agricultural crop production. The soils studied are classified as Haploxeralfs and Rhodoxeralfs. The texture of the soils ranges from clay to clay‐loam and sandy‐clay‐loam. The pH ranges from 5.2 to 7.69, the organic matter ranges from 3.01 to 6.3%, the calcium carbonate (CaCO3) ranges from 0 to 5.3%, the redness rating ranges from 2.5 to 6.3, and the ratio (Fed−Feo)×100/Fed, which is an index of the degree of crystallization of the iron (Fe) oxides, ranges from 45.17 to 93.34. The parent materials of the soils were limestones, schist‐gneiss, flysch‐marl, alluvium, and ophiolites. In the clay fraction, kaolinite and micas dominate, whereas in the fine sand fraction, quartz and feldspars dominate. This study indicated that the Mediterranean climate affects many soil properties, and the efficient water use and fertilization by crops was crucial to the sustainability of Mediterranean agriculture.

Neodymium sorption by clay minerals and zeoliferous rocks

The sorption of neodymium from its aqueous solutions (concentration range approx. 10–450 mg l−1) by montmorillonite, kaolinite and a clinoptilolite-containing rock has been investigated, using147Nd as radioactive tracer and γ-ray spectrometry. The neodymium uptake by montmorillonite was found to be much higher than of the other two materials in the whole investigated concentration range. However, in the case of montmorillonite and zeoliferous rock, the uptake ability is lower than that allowed by the measured CEC values and can be described by Langmuir-type equations. In the case of kaolinite, the observed higher than CEC-allowed uptake values could be attributed to sorption by mechanisms other than ion-exchange. The corresponding data obey a Freundlich-type sorption equation. Among the three geological materials investigated, montmorillonite exhibits the highest perspectives of application for the treatment and disposal of neodymium and trivalent actinides in nuclear industry.