Ioannis Massas

Variations in plant and soil lead and cadmium content in urban parks in Athens, Greece

The concentrations of Pb and Cd were studied in the plant species Pittosporum sinensis (Mock-orange) and Nerium oleander (Oleander) and in the soil of two major parks of Athens. The composition and the density of vegetation differs remarkably in the two parks. The concentrations of both metals were considerably higher at the peripheral zones and decreased towards the interior of the parks. At a distance of 60 m from the periphery to central zones the values almost reached background levels. The degree of plant and soil contamination was well correlated to the density and the structure of vegetation, the traffic volumes, the nature of the leaf surface of the two plants and the wind velocity.

Use of residues and by-products of the olive-oil production chain for the removal of pollutants from environmental media: A review of batch biosorption approaches.

Residues and by-products of the olive-oil production chain have been widely studied as biosorbents for the removal of various pollutants from environmental media due to their significant adsorption properties, low cost, production at local level and renewability. In this review, adsorbents developed from olive-tree cultivation residues and olive-oil extraction by-products and wastes are examined, and their sorption characteristics are described and discussed. Recent information obtained using batch sorption studies is summarized and the adsorption mechanisms involved, regarding various aquatic and soil pollutants (metal ions, dyes, radionuclides, phenolic compounds, pesticides) are presented and discussed. It is evident that several biosorbents show the potential to effectively remove a wide variety of pollutants from aqueous solutions, especially Pb and Cd. However, there is need to (a) develop standardized batch study protocols, and potentially reference materials, for effective cross-evaluation of biosorbents of similar nature and for improved understanding of mechanisms involved and (b) investigate scaling-up and regeneration issues that hold back industry-level application of preselected adsorbents.

Fractionation of heavy metals and evaluation of the environmental risk for the alkaline soils of the Thriassio plain: a residential, agricultural, and industrial area in Greece

The purpose of the present study is to test metals’ accumulation and behavior in surface soils of Thriassio plain, Attica, an area registered as probably the most polluted in Greece. Avoiding sampling close to obvious specific pollution sources, 50 surface soil samples were collected and the Tessier fractionation scheme was applied to determine the chemical partitioning of Pb, Cu, Zn, Ni and Cr. Five chemical fractions of the studied metals were defined: exchangeable (F1), acid-soluble (F2), reducible (F3), oxidizable (F4) and residual (F5). The highest Cu, Ni and Cr concentrations were measured in the residual fraction, while the highest Zn and Pb concentrations were found in the reducible fraction. However, F3 Cr and Ni concentrations were also high. These increased amounts of Zn and Pb and to a lesser extent those of Cr and Ni found in the reducible fraction indicate a potential hazard of metals’ mobilization under flooding and anaerobic conditions due to excess irrigation or rain water. Concentration of Pb in F1 was high suggesting recent pollution episodes. Principal component analysis (PCA) showed that the exchangeable fraction of Zn, Pb, Cr and Ni is strongly related to the soil clay content and the oxidizable fraction of Cr and Ni to organic matter content. According to PCA results, no other clear relation between the extracted metal fractions and the soil components (i.e. CaCO3 eq., organic matter, clay and amorphous iron oxides) was observed. The weak relation of CaCO3 eq., content with many metal fractions suggests that carbonates affect the chemical partitioning of metals in alkaline soils with high CaCO3 eq., content. The high values of mobility factor for Pb, Cu, Ni and Zn point to a considerable risk since these metals may accumulate in soil biota and plants.

Plant uptake of 134Cs in relation to soil properties and time.

134Cs uptake by sunflower and soybean plants grown on seven different soils and its relation to soil properties were studied in a greenhouse pot experiment. Soil in each pot was contaminated by dripping the 134Cs in layers, and sunflower and soybean plants were grown for three and two successive periods, respectively. 134Cs plant uptake was expressed as the transfer factor (TF) (Bq kg(-1) plant/Bq kg(-1) soil) and as the daily plant uptake (flux) (Bq pot(-1) day(-1)) taking into account biomass production and growth time. For the studied soils and for both plants, no consistent trend of TFs with time was observed. The use of fluxes, in general, provided less variable results than TFs and stronger functional relationships. A negative power functional relationship between exchangeable potassium plus ammonium cations expressed as a percentage of cation exchange capacity of each soil and 134Cs fluxes was found for the sunflower plants. A similar but weaker relationship was observed for soybean plants. The significant correlation between sunflower and soybean TFs and fluxes, as well as the almost identical highest/lowest 134Cs flux ratios, in the studied soils, indicated a similar effect of soil characteristics on 134Cs uptake by both plants. In all the studied soils, sunflower 134Cs TFs and fluxes were significantly higher than the respective soybean values, while no significant difference was observed in potassium content and daily potassium plant uptake (flux) of the two plants.

134Cs uptake by four plant species and Cs-K relations in the soil-plant system as affected by Ca(OH)2 application to an acid soil.

Three rates of Ca(OH)(2) were applied to an acid soil and the (134)Cs uptake by radish, cucumber, soybean and sunflower plants was studied. The (134)Cs concentration in all plant species was reduced from 1.6-fold in the sunflower seeds to 6-fold in the soybean vegetative parts at the higher Ca(OH)(2) rate. Potassium (K) concentration in plants was also reduced, but less effectively. The significantly decreased (134)Cs-K soil to plant distribution factors (D.F.) clearly suggest a stronger effect of soil liming on (134)Cs than on K plant uptake. This observation was discussed in terms of ionic interactions in the soil matrix and within the plants. The results also indicated that the increased Ca(2+) concentration in the exchange phase and in the soil solution along with the improved root activity, due to the soil liming, enhanced the immobilization of (134)Cs in the soil matrix and consequently lowered the (134)Cs availability for plant uptake.

Sorption Behavior of Cesium in Two Greek Soils: Effects of Cs Initial Concentration, Clay Mineralogy, and Particle-size Fraction

The characteristics of Cs sorption behavior in two soils (soil 1 and soil 2) with nearly the same clay content and exhangeable K concentration, but with different clay mineralogy, were studied by the quantification of the distribution coefficient (kd). It was observed that as the initial Cs concentration increased from 4 to 50 mg L−1, the kd values decreased in both soils, suggesting a progressive saturation of Cs available sorption sites. However, the presence of expansible 2:1 phyllosilicates minerals in the clay fraction of soil 2 maintained a high Cs sorption ability for this soil, even at high Cs concentrations. The experimental data were also fitted to the Freundlich isotherm and the results showed that parameters of the Freundlich equation could be used to estimate the degree of Cs sorption and the nature of the available sorption sites. For the studied soils, the kf and the kd values followed a similar trend and the n Freundlich constant values provided a reliable indicator for the soils’ clay mineralogy. The removal of the sand fraction enhanced Cs sorption in both soils and the absence of sorbed Cs ions on the quartz minerals, as observed by the SEM analysis, additionally supported the effect of particle-size fraction on Cs sorption.

NaOH pretreatment of compost derived from olive tree pruning waste biomass greatly improves biosorbent characteristics for the removal of Pb2+ and Ni2+from aqueous solutions

Compost derived from olive tree pruning waste (COTPW) was modified with 0.1 M (COTPW-1) and 1 M (COTPW-2) NaOH. The two biosorbents were tested for their ability to remove Pb2+ and Ni2+ ions from aqueous solutions. The effects of contact time, initial heavy metal concentration and solution temperature on the removal efficiency of COTPW-1 and COTPW-2 were also investigated. Among the two biosorbents, COTPW-1 showed a higher cation-exchange capacity (COTPW-1 = 130.4 cmolc/kg, COTPW-2 = 119.5 cmolc/kg) and lower % biomass loss due to the alkali treatment (COTPW-1 = 39.16, COTPW-2 = 60.6). Maximum Pb2+ and Ni2+ biosorptions at pH 5 and 25°C was 357.14 and 172.41 mg/g for COTPW-1, whereas for COTPW-2 they were 294.12 and 147.06 mg/g, respectively. The equilibrium adsorption data fitted well with the Langmuir isotherm and the pseudo-second-order model. Slightly reduced removal of Ni2+ from the solutions was observed in the presence of Pb2+, but Pb2+ removal was not affected by the presence of Ni2+ in the solutions. About 0.1 N HNO3 sufficiently recovered both metals from the tested materials (>95.01%). Overall, mild treatment of COTPW with NaOH greatly improved sorption characteristics.

Efficient urea-N and KNO3-N uptake by vegetable plants using fertigation

Vegetable production demands high nitrogen inputs. Fertigation is a means to increase fertilizer-N use by plants. However, the effect of different N sources and doses, and how they relate to the total available N in soils are poorly known. In this study we applied 15N-labeled fertilizers to green pepper in the field using a drip irrigation system during the dry summer. KNO3-N and urea-N were applied at a total of 6, 12 and 18 g plant−1. Our results show that urea was as effective as KNO3 as a N source. The fertilizer-N utilization efficiency was dramatically reduced at higher N doses, from 48% for the 6 g N plant−1 dose to 36% and 26% for the 12 and 18 g N plant−1 doses, respectively. However, the N in plants derived from fertilizer consistently exceeded 60%, indicating high availability of fertilizer-N even at the lowest dose. Negative added nitrogen interactions — the effect of added N on the fate of soil-N — were observed, particularly at high fertilizer-N doses. The fertilizer-N utilization efficiency calculated by the difference method was lower compared with the 15N enrichment method. This clearly indicates luxury N applications and excess N availability brought about by precise localized placement of fertilizer-N that leads to limited uptake of the available soil-N. N leaching risks in the following rain period should therefore be based on both the residual fertilizer-N and the increased amounts of residual soil mineral-N.

Microclimatic conditions and levels of pollution in public squares, in Athens, Greece

Relative humidity and air temperature regimes were studied in public squares of Athens, that differ in size and the composition and density of vegetation. Pb and Cd concentrations were also measured in the plant species Cynodon dactylon (L.) Pers. (Bermunda grass) and the soil of all the studied squares. Relative humidity and temperature values showed a differentiation between the inner sites of the larger squares (0.5 and 1.0 ha) and the surrounding building areas (increase of relative humidity and decrease of temperature), whereas for the 0.1 ha squares no such observation was obtained. However, the impact of squares’ microclimatic conditions on the adjacent building areas is negligible in all cases. Elevated Pd and Cd levels, that reduced from the periphery to the inner sites, were measured in Cynodon and soil of all the studied squares. The significant correlations of Pb to Cd in Cynodon and soil and of Pb and Cd in Cynodon to Pb and Cd in soil indicate that both metals originate from the same source,...

Effects of Time and Glucose-C on the Fractionation of Zn and Cu in a Slightly Acidic Soil

The effects of time and a labile carbon (C) source on the fates of zinc (Zn) and copper (Cu) were investigated in a slightly acidic soil in a two-factor experiment. Glucose was used as the C source to examine the effect of the expected flush of microbial activity on Zn and Cu extractability during the experimental period. The soil was amended with 500 mg kg−1 soil of Zn and Cu in the form of nitrate salts and with 4 g kg−1 glucose where appropriate, producing M (heavy metals, no glucose) and MG (heavy metals, with glucose) treatments. The treated soil samples were incubated for 3 h, 1 day (24 h), 3 days (72 h), 10 days (240 h), 30 days (720 h), and 60 days (1440 h) at 20 °C at constant moisture (≈50% of the soils water-holding capacity). At the end of each incubation period, destructive sampling was followed by a Tessier sequential extraction procedure that yielded five metal fractions for both Zn and Cu, defined as exchangeable, acid-soluble, reducible, oxidizable, and residual. The exchangeable fraction of Zn and Cu (considered to be an availability measure) showed decreasing trends over time, while the opposite was observed for the other fractions. The presence of glucose resulted in significantly lower exchangeable fractions in the “polluted soil” for both metals up to 720 h, pointing to lower Zn and Cu availability. Redistribution from less-available forms back to exchangeable forms occurred during the second month of incubation, suggesting a sharp decline in microbial activity and a consequent remobilization and potentially increased Zn and Cu bioavailability. However, glucose did not affect Zn and Cu availability in the control soil; this indicated that its effect is mainly observed following recent pollution events. Field applications of glucose at 4 g kg−1 soil is impractical in practice; future experimentation to estimate a minimum effective application rate or an alternative form of labile C, probably derived from recycling renewable labile organic materials, is warranted.