Dionisios Gasparatos

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.

Signs for secondary buildup of heavy metals in soils at the periphery of Athens International Airport, Greece

Emissions from civil airports are similar to those observed in industrial and urban areas. While air pollution and noise levels are regularly monitored and assessed, information on the status of heavy metals in soils close to airport facilities is limited. In this study, we monitored and assessed heavy metal distribution in soils close to Athens International Airport (AIA) in Attica, Greece. Following a grid sampling scenario, topsoil samples were collected from 86 sites at the periphery of AIA and total and available forms of Cu, Zn, Fe, Mn, Ni, Cr, Pb, and Ba concentrations were determined in aqua regia and DTPA soil extracts, respectively. Median concentration values for both metal forms are not considered as particularly high. However, 90th percentile concentration values for some metals are high, indicating soil enrichment. Evaluation of enrichment factor (EF) and availability ratio (AR) values and EFs spatial distribution have led to consistent conclusions of secondary and ongoing metal accumulation in the soils of the studied area. Tessier sequential extraction procedure was applied to 10% of the soil samples and the results showed high potential availability of Pb, Mn, Cu, and Ni, further supporting the continuous metal accumulation in the studied soils.

A critical assessment on arsenic partitioning in mine-affected soils by using two sequential extraction protocols

ABSTRACT The highly degraded mine-affected soils of Lavrion, central Greece, are greatly polluted by heavy metals and arsenic (As). To assess As partitioning in the soils of the area, Wenzel and BCR (Community Bureau of Reference) sequential extraction procedures (SEP) were applied to 29 top soils. The results of the Wenzel SEP showed that As was mainly bound to the well-crystallized (33.3%) and to the amorphous/poorly-crystalline (30.1%) oxides of Fe, Al, and Mn. According to the BCR scheme, most of the total As (78.4%) was retained in the residual phase. Low mobility factor values (Wenzel: 0.34%; BCR: 1.56%) clearly demonstrate the low availability and mobility of As in the studied soils. The specifically-sorbed/inner-sphere and the reducible fractions of As, obtained by the Wenzel SEP, were positively correlated with clay and Fe oxides content, respectively. The reducible As fractions of both SEPs were negatively correlated with carbonates content indicating that carbonates may partially control As sorption on Fe oxides. The comparative evaluation of the two SEPs showed that the application of the BCR protocol in contaminated soils cannot provide reliable information on As sequestration in soils but it can be a first estimate of As labile forms.

Chromium uptake by lettuce as affected by the application of organic matter and Cr(VI)-irrigation water: Implications to the land use and water management

Toxic chromium [(Cr(VI)] in food chain has created an alarming situation for human life and ecosystems. The present study through a greenhouse pot experiment aims to (a) investigate the ability of organic matter in reducing Cr uptake by lettuce (Lactuca sativa L.) from a sandy loam soil irrigating with Cr(VI)-water, (b) to provide a way for the restriction of Cr transfer from contaminated soils and irrigation water to plants/crops and (c) to contribute to the better management of soil (land) and water use, without reduction of the agricultural production. Since soil and groundwater contamination by Cr is a potential risk in a worldwide scale, due to industrial activities and/or natural processes, organic carbon may play a key role in the mobility of added Cr(VI) to soil via irrigation water, in a significant way. The cultivation of lettuce, using organic matter in the form of leonardite (10 and 30 wt%) and Cr(VI)-irrigation water (100, 200 and 300 mgL-1), showed that the uptake of Cr in both shoots and roots increased with increasing concentration of Cr in the irrigation water. The highest Cr values in shoots (average = 10 mg/kg) and in roots (average = 28 mg/kg) were recorded in those plants cultivated in soil after the addition of Cr(VI)- water without organic matter, whereas the lowest Cr values in shoots (average = 0.44 mg/kg) and in roots (average = 0.7 mg/kg) were recorded in those plants cultivated in soil with addition of 30 wt% organic matter. The used leonardite as organic matter that is an oxidized form of lignite, due to its high content of humic acid is considered to be a useful organic fertilizer that provides possibilities for combining food production with soil protection. Therefore, the application of the natural organic material leonardite, as a land management technique, seems to be a cost-effective method consistent to related protocols for the protection of the soil quality.

Sustainable Management of Soil Phosphorus in a Changing World

Phosphorus (P) is an important nutrient for flora and fauna, and is an essential element during energy transformation processes of the living world. Phosphate rock, which is the most common source of phosphorus, is globally used in various forms, in order to boost agricultural productivity and cover contemporary food demand. Its low price in combination with its abundance on several areas on our planet led to overexploitation phenomena and unsustainable phosphorus management, resulting in important environmental and socio-economic problems. Eutrophication, soil over-accumulation, nutrient depletion due to soil erosion processes, contamination of the extraction sites, reduction of global available resources, massive price fluctuations and food crisis are some of these phosphorus-related problems with a global impact. The uncertainties and the underlying risks prevailing due to improper use of phosphate resources denote that sustainable soil phosphorus management should be set amongst the top priorities in global level. The local adaptation of the 4R Nutrient Stewardship approach can be proved a very promising tool in order to develop a sound soil phosphorus management program. In Europe, despite the multi-dimensional problems caused by unsustainable phosphorus use of the previous decades, significant steps are taken to restore the problems and establish a framework focusing on natural resources and socio-economic system protection.

Micronutrient Content in Relation to Specific Leaf Area, Light Regime and Drenched-Applied Paclobutrazol in Lantana Camara L.

Iron and manganese are essential microelements on plant growth but no information is known with regard to their content on Lantana camara L. subsp. camara (lantana) treated with drenchedapplied paclobutrazol. Thus, the effects of drenched-applied paclobutrazol [0 (control), 40, and 80 mg l-1] on leaf iron and manganese contents of lantana plants were investigated testing two light regimes, resulted from the establishment of different shading levels, 0% (daily light quantity of 27.8 mol m-2 d-1) and 66% (9.4 mol m-2 d-1) in a glasshouse in Attica, Greece. Possible correlations between the studied minerals contents (iron and manganese) and specific leaf area were examined. Analysis of variance showed that iron and manganese contents were affected by shading level, paclobutrazol, their interaction and paclobutrazol, respectively. Iron content increased significantly after treatments with paclobutrazol, compared to control, at full light environment (0% shading). Leaf manganese content presented no significant increase with the increasing paclobutrazol concentrations at 0% and 66% shadings. No significant differences were noted (dispensing control plants) on iron and manganese contents, when examining plants which were treated with the same paclobutrazol concentration, between the studied light environments. From the linear correlation analysis, manganese content exhibited a significant negative correlation with specific leaf area which was not shown by the iron content. The results of the present study could contribute to establishing iron and manganese sufficiency ranges on L. camara, especially after treatments with different light environments and paclobutrazol concentrations.