Soil Contamination by Heavy Metals and Metalloids

Soils are central to life on Earth because they provide food, clean water, and air due to their filtering capacity; raw materials; habitats for living organisms; and climate resilience via carbon sequestration, therefore supporting a variety of ecosystem services [...

Detailed Soil Survey Field and Laboratory Data as a Critical Tool for Optimizing the Arable Cropping Capability Evaluation of a Representative Episaturated Soil Pedon in Greece

The objective of the present work is to contribute to the examination of the interconnections between soil classification/soil mapping and soil capability for agricultural use. A pedon scale analytical field along with laboratory data of an episaturated agricultural soil of Thessaly (Greece), allowed for the optimization of soil fertility class evaluation and its corresponding agricultural value. Specific soil properties, low chroma colors and the distribution of redoximorphic features within the soil profile (Fe-Mn concretions) revealed the presence of impermeable argillic horizons, resulting in a perched water table in late winter and spring. The evaluation of the soil pedon was carried out through the accurate parameterization and implementation of a technical soil classification system and a soil rating method, both of which are well known worldwide, and which use detailed soil survey data. The results confirmed the general principle that only by using detailed soil survey field and laboratory data can any technical soil classification system or soil rating method be adapted and properly applied. Both the classification system and the scoring methodology of the soil profile reached the same conclusion: characterizing the studied soil as of good potential for general arable cropping or as of fair agricultural value. This was achieved only by considering the phenomenon of episaturation, which emerged from the plethora of detailed soil survey data, guiding the classification system and the scoring methodology to produce reliability and represent real situation results

Detailed Soil Survey Field and Laboratory Data as a Critical Tool for Optimizing the Arable Cropping Capability Evaluation of a Representative Episaturated Soil Pedon in Greece

The objective of the present work is to contribute to the examination of the interconnections between soil classification/soil mapping and soil capability for agricultural use. A pedon scale analytical field along with laboratory data of an episaturated agricultural soil of Thessaly (Greece), allowed for the optimization of soil fertility class evaluation and its corresponding agricultural value. Specific soil properties, low chroma colors and the distribution of redoximorphic features within the soil profile (Fe-Mn concretions) revealed the presence of impermeable argillic horizons, resulting in a perched water table in late winter and spring. The evaluation of the soil pedon was carried out through the accurate parameterization and implementation of a technical soil classification system and a soil rating method, both of which are well known worldwide, and which use detailed soil survey data. The results confirmed the general principle that only by using detailed soil survey field and laboratory data can any technical soil classification system or soil rating method be adapted and properly applied. Both the classification system and the scoring methodology of the soil profile reached the same conclusion: characterizing the studied soil as of good potential for general arable cropping or as of fair agricultural value. This was achieved only by considering the phenomenon of episaturation, which emerged from the plethora of detailed soil survey data, guiding the classification system and the scoring methodology to produce reliability and represent real situation results

Efficacy of EDTA and Olive Mill Wastewater to Enhance As, Pb, and Zn Phytoextraction by Pteris vittata L. from a Soil Heavily Polluted by Mining Activities

A pot experiment was conducted to evaluate the effect of Na2-EDTA 0.01 M (E) and olive mill wastewater 15% (OMW) on As, Pb, and Zn uptake by Pteris vittata L. grown in a soil highly contaminated by mining activities. A two-factor experimental design was followed; 3 treatments (E, OMW, and E + OMW) × 2 batches (single or double dose). Six weeks after the P. vittata transplanting, all pots received the selected dose of each treatment (Batch I). At 8 weeks, in half of the pots, a second dose of the same treatments was added (Batch II). Plants were harvested after 10 weeks and As, Pb, and Zn concentrations were determined in fronds and roots. Depending on the element, both treatment and batch effects were significant. In Batch II, EDTA application resulted in a 55% increase of As and 9- and 4-fold of Pb and Zn concentrations in the fronds, while OMW treatment substantially reinforced plant uptake when combined with EDTA. Roots to fronds translocation of the metal(loid)s highly increased in Batch II. After harvest, composite soil samples of all treatment–batch combinations were subjected to sequential extraction, but no significant differentiations of As, Pb, and Zn partitioning in soil phases were detected

Selenium Uptake by Lettuce Plants and Se Distribution in Soil Chemical Phases Affected by the Application Rate and the Presence of a Seaweed Extract-Based Biostimulant

To tackle selenium (Se) malnutrition, biofortification is among the proposed strategies. A biostimulant application in soils is thought to support a plant’s growth and productivity. Biofortification with Se(VI) may lead to a leaching hazard due to the high mobility of Se(VI) in the soil environment. In this study, the effect of the application of two Se(VI) rates—5 and 10 mg kg−1 soil—and a biostimulant on the Se uptake by lettuce plants and on the Se(VI) distribution in soil fractions following the plants harvest, was investigated. Phosphorus (P) and sulfur (S) concentrations in plants were also determined. A high Se(VI) rate suppressed plant growth, leading to a significant fresh weight decrease from 12.28 to 7.55 g and from 14.6 to 2.43 g for the control and high Se(VI) without and with biostimulants, respectively. Impaired plant growth was verified by the SPAD, NDVI and NDRE measurements. The significantly highest Se concentration in plants, 325 mg kg−1, was recorded for the high Se(VI) rate in the presence of the biostimulant. Compared to controls, the low Se(VI) rate significantly decreased P and increased the S concentrations in plants. The post-harvest soil fractionation revealed that, in the presence of the biostimulant, the Se(VI) soluble fraction increased from 0.992 to 1.3 mg kg−1 at a low Se(VI) rate, and decreased from 3.T85 to 3.13 mg kg−1 at a high Se(VI) rate. Nevertheless, at a low Se(VI) rate, 3.6 and 3.1 mg kg−1 of the added Se(VI) remained in the soil in less mobile forms, in the presence or absence of the biostimulant, respectively. This study indicated that the exogenous application of Se in soil exerted dual effects on lettuce growth and Se availability, depending on the level of selenate applied

Selenium Uptake by Lettuce Plants and Se Distribution in Soil Chemical Phases Affected by the Application Rate and the Presence of a Seaweed Extract-Based Biostimulant

To tackle selenium (Se) malnutrition, biofortification is among the proposed strategies. A biostimulant application in soils is thought to support a plant’s growth and productivity. Biofortification with Se(VI) may lead to a leaching hazard due to the high mobility of Se(VI) in the soil environment. In this study, the effect of the application of two Se(VI) rates—5 and 10 mg kg−1 soil—and a biostimulant on the Se uptake by lettuce plants and on the Se(VI) distribution in soil fractions following the plants harvest, was investigated. Phosphorus (P) and sulfur (S) concentrations in plants were also determined. A high Se(VI) rate suppressed plant growth, leading to a significant fresh weight decrease from 12.28 to 7.55 g and from 14.6 to 2.43 g for the control and high Se(VI) without and with biostimulants, respectively. Impaired plant growth was verified by the SPAD, NDVI and NDRE measurements. The significantly highest Se concentration in plants, 325 mg kg−1, was recorded for the high Se(VI) rate in the presence of the biostimulant. Compared to controls, the low Se(VI) rate significantly decreased P and increased the S concentrations in plants. The post-harvest soil fractionation revealed that, in the presence of the biostimulant, the Se(VI) soluble fraction increased from 0.992 to 1.3 mg kg−1 at a low Se(VI) rate, and decreased from 3.T85 to 3.13 mg kg−1 at a high Se(VI) rate. Nevertheless, at a low Se(VI) rate, 3.6 and 3.1 mg kg−1 of the added Se(VI) remained in the soil in less mobile forms, in the presence or absence of the biostimulant, respectively. This study indicated that the exogenous application of Se in soil exerted dual effects on lettuce growth and Se availability, depending on the level of selenate applied

Map-based soil crusting susceptibility assessment using pedotransfer Rules, CORINE and NDVI: A preliminary study in Greece

Map-based assessment of land degradation processes supports national monitoring and protection of the soil resources, in line with the Land Degradation Neutrality (LDN) and the Sustainable Development Goals (SDGs) initiatives. Soil crusting susceptibility, a complex expression of land degradation, with fundamental impact on soil functions, has not yet been estimated in Greek territory. To address this knowledge gap, current research uses well-known pedotransfer rules (PRLeB), partially adjusted to suit the local soil database format. The PRLeB, already applied at European scale, examine the soil crusting problem as a function of fundamental soil characteristics. From the first analysis a paradox emerged. Moderately and highly crusting prone soils were encountered in forested areas. This paradox indicated the need for a second formalization of the soil crusting problem (ePRLeB). The CORINE Land Cover (CLC) 2018 and a seasonal vegetation cover index (Normalized Difference Vegetation Index -NDVI) were used to divide the study area into categories and to capture the temporal variability of the problem, accordingly. Three land use categories emerged. The water bodies and the artificial areas were characterized as Non-evaluated areas (NE). Areas with considerable vegetation coverage (NDVI greater than 0.5) were characterized as Non-prone to crusting (NC), and the rest of the areas were characterized as Potentially prone to crusting (PC). The PRLeB approach was applied only to the PC areas. In both formalizations, the physicochemical and textural aspects of soil crusting adopted the same PRLeB. With the first formalization, 15% and 39% of the soils in Greece were characterized as very low and low susceptible to soil crusting respectively. With the second formalization 58 – 63% of the soils were characterized by no and 5 – 7% by very low crusting susceptibility. Current work explored two fundamentally different facets of the soil crusting problem. The first formalization, which can be expressed as the soil susceptibility to crusting, considers crusting as an inherent soil process. The second formalization, expressed as soil crusting susceptibility encounters crusting as a complex phenomenon involving natural but not anthropogenic factors. The study indicated that vegetation and seasonality are important factors in the map-based assessment of the observable soil crusting phenomenon. Also, it was highlighted that the unambiguous problem specification is a critical aspect for complex problem assessment and communication, particularly within an interdisciplinary context

Apricot Tree Nutrient Uptake, Fruit Quality and Phytochemical Attributes, and Soil Fertility under Organic and Integrated Management

Organic cultivation management has generated a great deal of interest during the last decades. As there are numerous conflicting results in the literature on the superiority of organic cultivation over an integrated one, a trial occurred using two apricot cultivars, i.e., ‘Bebecou’ and ‘Diamantopoulou’, under integrated and organic cultivation (three orchards per cultivation system and cultivar). The trial occurred during a single cultivation period under different soil but the same climatic conditions. Fruit physiological (weight, diameters, skin color), organoleptic (pH, titratable acidity, and total soluble solids), and phytochemical (phenolic compounds, carbohydrates, organic acids, antioxidant activity, and carotenoids) attributes were assessed, along with plant nutrition, soil fertility status, and a sensory evaluation panel. The two cultivation practices exhibited similar effects in many of the parameters studied in this trial as well as small differences. Fruit weight was higher under organic management in ‘Bebecou’ and under integrated in ‘Diamantopoulou’, while copper was found at a higher concentration in the leaves of organically managed trees of both cultivars. The cultivar was found to have the greatest effects on the measured variables, while within each cultivation management, the farm also had a great impact, indicating that the outcome of specific cultivation practice is influenced by so many factors that it is almost impossible to come to a general conclusion about which practice is the best. Therefore, more research is needed, focused not only on the differences between organic and integrated cultivation management but primarily on the influence of specific cultivation practices within the same management system, to be able to elucidate, to some extent, the effects of individual factors on the measured variables

Evaluation of Biobed Bio-Mixture from Olive Oil Mill Wastewater Treatment as a Soil Organic Amendment in a Circular Economy Context

This study, based on circular economy principles and sustainable development practices, aims to present the results of soil samples analysis after their mixture with a biobed bio-mixture of straw, soil and compost, used for two consecutive years as organic bio-filter of olive oil mill wastewater. So far, exhausted bio-mixtures used in biobeds to minimize pesticide point-source contamination turned out to contain residues of pesticides, and they are considered hazardous wastes; thus, they require special treatment before their disposal. Contrariwise, saturated bio-mixtures from bio-bed systems utilized for olive mill wastewater (OMWW) treatment not only do not require any special treatment before their final disposal but also can be exploited as a soil amendment. To this end, the effects of the used bio-mixture application in three different proportions as a soil amendment on the physical and chemical properties of medium-texture soil were investigated. The application of water simulating a typical irrigation period during a growing season took place. Upon completion of the water application, soil samples were collected from two different depths of the columns and analyzed, and leachates collected from the columns were also analyzed. Soil texture, organic matter, calcium carbonate, electrical conductivity (EC), pH, total nitrogen, nitrates, nitrites, ammonium, available phosphorus, exchangeable potassium, sodium, calcium and magnesium, exchangeable sodium percentage (ESP), cation exchange capacity (CEC), available iron, manganese, copper, zinc and boron were monitored in the soil samples as indexes of potential soil amendment, and EC, pH, nitrates, potassium, sodium, calcium, magnesium, sodium adsorption ratio (SAR), total hardness, iron, manganese, copper, zinc and boron were monitored in the leachates as indexes of potential groundwater contamination.The study demonstrated the effective use of saturated bio-mixture as an organic soil amendment, while the impact of selected amendments on groundwater was the minimum