Concentrations and Availability Indicators of Soil Heavy Metals; the Case of Children’s Playgrounds in the City of Athens (Greece)

This study reports on the concentrations, distribution, and availability of heavy metals in the children’s playground soils of Athens. Playgrounds were chosen because they are open city areas; they show relatively even spatial distribution within the district of Athens and are used by a great number of young children and their escorts on a regular basis. Samples were collected from 70 playground surface soils, representing more than 70% of the city’s playgrounds. Cu, Zn, Pb, Cr, Ni, Co, Mn, and Fe were extracted by aqua regia and by diethylene triamine pentaacetic acid (DTPA) to estimate total and available metal forms, respectively. Their mean total concentrations were 43, 174, 110, 80, 82, 22, 312, and 17?×?10³?mg kg^?1, respectively. The DTPA-extracted fraction showed much lower values, with means of 2.5, 7.8, 5.8, 1.5, 1.3, 0.4, 8.4, and 2.0 mg kg^?1 respectively, which, however, should be carefully monitored since they relate directly to the bioavailable fraction of heavy metals. Though mean values of metal concentrations are not particularly high, the calculated enrichment factors indicate site-specific cases of high enrichment with heavy metals. Considering that the bioavailable fraction of a metal is possibly a more appropriate indicator for the recent soil pollution history, availability ratios were calculated and their distribution was visualized over the entire city profile using the appropriate GIS software. It was shown that recent metal pollution events appear to have affected mostly playground sites in the southern and eastern part of the municipality.     

Spatial and vertical distribution of <Superscript>137</Superscript>Cs in soils in the erosive area of southeastern Serbia (Pčinja and South Morava River Basins)

Purpose

The area of southeastern Serbia, the P?inja and South Morava River Basins, is under the influence of very strong erosion, and the aim of this study was to investigate the vertical and spatial distribution of the ¹³⁷Cs in the eroded soils of this area.

Materials and methods

Vertical soil profiles were collected with 5-cm increments from the uppermost layer down to 20, 25, 30, 40, and 50 cm of depth, depending on the thickness of the soil layers, i.e., down to the underlying parent rocks. Measurements of ¹³⁷Cs activity concentration were performed by using the HPGe gamma-ray spectrometer ORTEC-AMETEK (34 % relative efficiency and high resolution 1.65 keV at 1.33 MeV for ⁶⁰Co), from its gamma-ray line at 661.2 keV.

Results and discussion

The mean ¹³⁷Cs activity concentration across all 18 soil profiles (for all soil layers) was found to be 20 Bq kg^?1. In the greatest number of soil profiles, the ¹³⁷Cs activity concentration was generally highest in the first soil layer (0–5 cm) and decreased with soil depth, while in a few soil profiles, the peak of either the ¹³⁷Cs activity concentration occurred in the second soil layer (5–10 cm) or the ¹³⁷Cs activity concentration was almost equal throughout the entire soil profile. The mean ¹³⁷Cs activity concentration in the first soil layer (0–5 cm) was found to be 61 Bq kg^?1, and the high coefficient of variation of 92 % pointed out high spatial variability and large range of the ¹³⁷Cs activity concentrations in the study area.

Conclusions

The obtained results indicate that in the greatest number of soil profiles, ¹³⁷Cs is present in the upper layers, with concentration decreasing with depth, as is typical in uncultivated soil. Its spatial distribution was very uneven among the surface soil layers of the investigated sites. One of the main reasons for such pattern of ¹³⁷Cs in the study area may be soil erosion. Additional investigations which would support this hypothesis are required.

     

Farmers’ adoption of maize (Zea mays L.) hybrids and the persistence of landraces in Southwest China: implications for policy and breeding

This paper examines changes in the distribution of maize hybrids and landraces in the mountainous areas of southwest China over 1998–2008, farmers’ reasons for cultivar adoption and the implications for national policies in relation to seed production and breeding, based on baseline data and a survey conducted in Guangxi, Yunnan and Guizhou. The study traced the dynamic changes in the adoption of hybrids and landraces in farmers’ fields, explored how individual farmer’s choices can influence local landrace distribution, and investigated the space for conducive policy and innovative action for on-farm conservation of maize genetic resources. The research showed that although there is strong farmers’ interest in accessing modern maize hybrids, farmers also express strong reasons for maintaining at least some of the landraces that satisfy local agronomic context and social preferences. Farmers recognized that hybrids have a number of advantages but they also indicated some disadvantages of the current available hybrids e.g. with respect to seed quality, local adaptability, taste and cost of seeds, but also lack of information on the performances of the new hybrids. Based on farmers’ reasoning and experiences, the requirements have been identified for improving yield combined with local preferences (agronomic, cultural and socio-economic). The paper concludes by identifying options for how China might seek to develop resilient seed systems for smallholder farmers in poor areas, under changing climatical conditions and volatile markets. Participatory Plant Breeding is among the options considered for bringing farmers’ needs into conservation and breeding strategies for improving local adaptation.     

Behaviour of Potassium and Trace Elements in Rhizosphere of Flue-Cured Tobacco (Nicotiana Tabacum L.)

The study on the behaviour of potassium,phosphate and trace elements,Fe,Mn,Cu and Zn,in the rhizosphere of different varieties of flue-cured tobacco (Nicotiana tabacum L.)with high and low potassium application rate with rhizobag technique showed that soil available K,soil available P,and slow available K was in depletion status,whereas DTPA extractable Fe,Mn,Zn and Cu accumulated obviously in rhizosphere.The depletion and accumulation rates of mineral nutrients differed in degree with K application rate,soil type,and tobacco variety.The content of available K in both rhizosphere and bulk soil and K concentration in tobacco leaf increased significantly,and the available P in rhizosphere dropped with more K application.The DTPA-Fe content of red soil much lower in pH was higher than that of calcareous soil in bulk soil.But the DTPA-Fe content of calcareous soil was much higher than that of red soil in rhizosphere,which was considered perhaps to be mainly related to releasing of Fe phytosiderophore.Nitrate coule increase depletion of a vailable K in rhizosphere and also soil pH in comparision with ammonium.     

For how long does the quality and quantity of residues in the soil affect the carbon compartments and CO<Subscript>2</Subscript>-C emissions?

Purpose

The mineralization/immobilization of nutrients from the crop residues is correlated with the quality of the plant material and carbon compartments in the recalcitrant and labile soil fractions. The objective of this study was to correlate the quality and quantity of crop residues incubated in the soil with carbon compartments and CO₂-C emission, using multivariate analysis.

Materials and methods

The experiment was conducted in factorial 4?+?2?+?5 with three replicates, referring to three types of residues (control, sugarcane, Brachiaria, and soybean), and two contributions of the crop residues in constant rate, CR (10 Mg ha^?1 residue), and agronomic rate, AR (20, 8, and 5 Mg ha^?1 residue, respectively, for sugarcane, soybean, and Brachiaria), evaluated five times (1, 3, 6, 12, and 48 days after incubation). At each time, we determined the CO₂-C emission, nitrogen and organic carbon in the soil, and the residues. In addition, the microbial biomass and water-soluble, labile, and humic substance carbons fractionated into fulvic acids, humic acids and humin were quantified.

Results and discussion

Higher CO₂-C emissions occurred in the soil with added residue ranging from 0.5 to 1.1 g CO₂-C m^?2 h^?1 in the first 6 days of incubation, and there was a positive correlation with the less labile organic soil fractions as well as residue type. In the final period, after 12 days of soil incubation, there was a higher relation of CO₂-C emission with carbon humin. The sugarcane and soybean residue (20 Mg ha^?1) promoted higher CO₂-C emission and the reduction of carbon residue. The addition of residue contributed to an 82.32 % increase in the emission of CO₂-C, being more significant in the residue with higher nitrogen availability.

Conclusions

This study shows that the quality and quantity of residue added to soil affects the carbon sequestration and CO₂-C emission. In the first 6 days of incubation, there was a higher CO₂-C emission ratio which correlates with the less stable soil carbon compartments as well as residue. In the final period of incubation, there is no effect of quality and quantity of residue added to soil on the CO₂-C emission.

     

Genotypic differences in the antioxidant and carbon–nitrogen metabolism of acid-tolerant and acid-sensitive rice (Oryzasativa L.) cultivars under acid stress

A pot experiment was conducted to investigate differences in antioxidative defence and carbon–nitrogen metabolism between acid-tolerant (YJSM) and acid-sensitive (YHSM) rice cultivars under acid stress. Acid-tolerant and acid-sensitive rice were planted in both acidic soil (pH 4.21) and normal soil (pH 6.13). Forty-eight days after sowing, rice shoots and roots from four treatments were collected, and the other four replicates were harvested at seed maturity. The results revealed that the grain yield of acid-tolerant YJSM was significantly higher than that of acid-sensitive YHSM under acid stress. The activities of antioxidant enzymes (superoxide dismutase and catalase) and contents of non-enzymatic antioxidants (ascorbate and reduced glutathione) of acid-tolerant YJSM were both higher than those of acid-sensitive YHSM under acid stress. Moreover, the enzyme activities (nitrate reductase, glutamine synthetase, glutamate synthase and glutamate dehydrogenase) and product contents (soluble sugar and soluble protein) of carbon–nitrogen metabolism of acid-tolerant YJSM were higher than those of acid-sensitive YHSM under acid stress. The NO₃^–N and carbon (C) contents in leaves of acid-tolerant YJSM were both significantly higher than those of acid-sensitive YHSM under acid stress. This study suggests that the acid-tolerant rice cultivar has better antioxidative defence and carbon–nitrogen metabolism systems than the acid-sensitive rice cultivar and is more effective in resisting acid stress.     

Effect of seed‐placed fertilizer on the emergence (germination) of soybeans (Glycine max L.) and snapbeans (Phaseolus vulgaris L.)

Abstract

Field trials were established on a loamy fine sand and a silt loam using snapbeans and soybeans as test crops, respectively. Row fertilizer was placed with the seed (seed‐placed). Treatments were arranged in a 3×3×3 factorial experiment, and N, P, and K were applied in all combinations at three rates (0, 3.4, and 6.8 kg/ha). Ammonium nitrate (AN), monoammonium phosphate (MAP), concentrated superphosphate (CSP) and potassium chloride (KCl) were used as sources of N, P and K. Additional treatments compared MAP with diammonium phosphate (DAP) and KCl with potassium nitrate (KNO₃).

The salt index of each treatment was inversely related to emergence, i.e. as the salt index increased, the emergence decreased. Level of N was more important than level of P or K in regards to reduction in emergence. Snapbeans grown on a loamy fine sand were extremely sensitive to damage from seed‐placed fertilizer, even at rates as low as 3.4 kg/ha of N, P or K. Soybeans planted on a silt loam soil were less sensitive than snapbeans planted on a loamy sand. The soybeans were able to tolerate up to 10.2 kg/ha of seed‐placed P plus K or 6.8 kg/ha of seed‐placed N plus P or N plus K without causing a significant delay in emergence.     

Assessing a suitable extractant and critical limits of nickel in soil and plant for predicting the response of barley (Hordeum vulgare L.) to nickel grown in Inceptisols

ABSTRACT

Nickel (Ni) is an essential element for plants. Abundant information exists on Ni toxicity in soil–plant system but not much is available on its critical level of deficiency (CLD) in soils and plants. Five chemical extractants were evaluated to find a suitable extractant for Ni in Inceptisol. Twenty-one soils having low to high levels of Ni were used to grow barley (Hordeum vulgare L). The amount of Ni extracted was correlated with Ni concentration and uptake by barley. The diethylene triamine penta acetic acid-calcium chloride (0.005 M DTPA-CaC1₂) was identified as the most promising soil extractant for Ni. The CLD of Ni for 0.005 M DTPA-CaC1₂ in soil was 0.22 mg kg^?1 whereas in barley plant it was 2.14 mg kg^?1. Application of 7.5 mg kg^?1 Ni in soil caused a significant increase in Ni concentration in the shoot of barley in all the soils irrespective of the initial Ni status.     

Live and death of streptomyces in soil—what happens to the biomass?

The formation of soil organic matter (SOM) has been proposed to depend on fragmentation of biomass after cell death. However, this is hard to mimic in laboratory experiments showing the process directly. We used heavy metal contamination in order to provide an environment in which one Streptomyces strain, the heavy metal resistant S. mirabilis P16B‐1, could survive while the sensitive strain S. lividans TK24 was expected to die and disintegrate; the necromass fragments would then contribute to SOM formation. Both strains were grown for 30 d in sterile mesocosms containing either highly metal‐contaminated soil from a former uranium‐mining site in Ronneburg, Germany, or control soil from a municipal park, Jena, Germany. The fate and morphology of living and dead bacterial biomass (necromass) was observed using scanning electron microscopy. Attachment of soil particles to the intact mycelium as well as decay of dead biomass was observed. Dead bacterial biomass was identified in form of patchy fragments while the superordinate filamentous structure of the hyphae was still visible and obviously stabilized in soil. The fate of cytosolic compounds was followed using the example of a nickel‐containing superoxide dismutase (NiSOD) which was found to be released after death of cells grown in liquid soil‐extract medium. Activity of the enzyme was proven for concentrated media supernatant by a gel‐based qualitative activity assay. This indicates that NiSOD remains active in soil after cell death. Hence, bacterial cell death results in the release of cytosolic compounds, e.g., intact proteins, as well as the formation of residual cell‐envelope fragments contributing to SOM formation.     

Assessment of the diversity of comfrey (Symphytum officinale L. and S. × uplandicum Nyman)

Genetic Resources and Crop Evolution - Comfrey Symphytum officinale L. (true comfrey) and S.?×?uplandicum Nyman (a hybrid between S. asperum Lepech?×?S. officinale...     

Do elevated soil concentrations of metals affect the diversity and activity of soil invertebrates in the long‐term?

This study aimed to elucidate the response of diversity and activity of soil invertebrates to elevated soil metal concentrations that were a result of sewage sludge application. Field sampling of soil invertebrates was carried out from 2002 to 2004 at an experimental site established in 1982 to test the effects on crop production of metal contamination from sewage sludge applications with elevated concentrations of zinc (Zn), copper (Cu) and nickel (Ni) with certain treatments exceeding the current UK statutory limits for the safe use of sludge on land. At metal concentrations within the limits, none of the invertebrates sampled showed adverse effects on their abundance or overall community diversity (from Shannon–Weiner index). At concentrations above the limits, individual taxa showed sensitivity to different metals, but overall diversity was not affected. Earthworm abundance was significantly reduced at total Cu concentrations at and above 176 mg kg^?1, while nematode and enchytraeid abundances were sensitive to Cu and high Zn concentrations. Correspondingly, litter decomposition was lower in Zn and Cu treatments although there was no direct relationship between decomposition and soil invertebrate abundance or diversity. Such enduring changes in both soil biodiversity and biological activity around the current UK regulatory limits warrant further investigation to determine whether they indicate detrimental damage to soil functioning over the long‐term.     

Fractionation and Bioavailability of Arsenic in the Bed Sediments of the Anllóns River (NW Spain)

The arsenic bioavailability in the bed sediments from the Anllóns River (NW Spain) has been assessed by using several analytical approaches. A six-step sequential fractionation was compared to three general availability tests: the Toxicity Characteristic Leaching Procedure (TCLP) extraction, which estimates the leaching potential of As and its effect on the survival of microorganisms (Vibrio fischeri), an extraction with 1 M HCl extraction, which estimates the bioavailability to higher plants, and a physiologically based extraction test (PBET), which estimates the bioavailability to superior animals. Arsenic was found to be mainly associated to the least mobile fractions: bound to Fe-Al oxides and in the residual phase. Among the three single extractants considered, the PBET extracted the highest As concentrations (1–11% of the total As). The TCLP extracts showed toxicity to Vibrio fischeri whereas for the plants evaluated, aqueous extracts did not show adverse effects.     

Semitic-language records of snake melons (<Emphasis Type="Italic">Cucumis melo</Emphasis>, Cucurbitaceae) in the medieval period and the “piqqus” of the “faqqous”

The snake melon, Cucumis melo subsp. melo Flexuosus Group, is a cucurbit crop that was grown and esteemed in Mediterranean lands in antiquity and classical times. Images of snake melons appear in ancient Egyptian wall paintings and sculptures and in mosaics from the Roman Empire. The sikyos of Greek, the cucumis of Latin, and the qishu’im of Hebrew, thought by many to be cucumbers, Cucumis sativus, have now been identified as snake melons. Less iconographic and written evidence exists concerning the appreciation of snake melons during the medieval period. The present work focuses on some philologically based evidence of the importance of snake melons leading into and including the medieval period, with two specific objectives. One was to trace the records of the Hebrew epithet piqqus, which applied to removal of the hairs of young cucurbit fruits, and the Arabic epithet faqqous, used historically and to the present day to designate snake melons. Another objective was to re-affirm how piqqus was actually conducted, as mandated in the second-century code of Jewish Oral Law known as the Mishna. Various conjugational forms of the Hebrew word piqqus were found in writings dating from 200 CE to approximately 600 CE. Evidence is presented that further establishes the exact meaning of piqqus as the rubbing off of the hairs of young cucurbit fruits. The Arabic word faqqous was found in writings dating from the beginning of the tenth century and through to the end of the medieval period in the fifteenth century, the writers hailing from Andalusia in the west to Iraq in the east. These writings suggest that the snake melon was a familiar vegetable across a wide geographic belt throughout the medieval period.     

Acid–Base Characteristics and Clay Mineralogy in the Rhizospheres of Norway Maple and Common Spruce and in the Bulk Mass of Podzolic Soil

Eurasian Soil Science - Acid–base characteristics and composition of clay minerals were estimated in the rhizospheres of Norway maple (Acer platanoides) and common spruce (Picea abies) and in...     

β-Glucosidase involvement in the formation and transformation of oleuropein during the growth and development of olive fruits (Olea europaea L. cv. Arbequina) grown under different farming practices

The present study investigates oleuropein metabolism, as well as the involvement of β-glucosidase during the growth, development, and ripening of olive fruit. The results show that in olive fruit the in vivo formation and transformation of oleuropein takes place in three different stages. The first one is characterized by a net accumulation of oleuropein and occurs in the immature fruit. In the second stage, associated with the green and light-green fruits, oleuropein content is maintained practically constant, and finally, a third stage that begins in the green-yellow fruit is characterized by a progressive decline of the oleuropein concentration. Our findings confirm that in the absence of β-glucosidase the Damtoft-proposed pathway is active and that net synthesis of oleuropein is unquestionable. β-Glucosidase activity plays a key role in the oleuropein metabolism catalyzing its in vivo hydrolysis.     

Review Article. What are the nature and formation conditions of hydroxy‐interlayered minerals (HIMs) in soil?

Primary minerals of the parent material undergo weathering during the formation of terrestrial soils to varying extent. As a result, secondary minerals develop, which comprise, among many others, hydroxy‐interlayered minerals (HIMs). These minerals have formed by interlayering of hydroxy‐metal complexes (especially of Al³⁺, also Mg²⁺, Fe^2+/3+) into micas, expansible 2:1 phyllosilicates and forming oligomers, or by weathering of primary chlorite. The degree of interlayer filling and the stability of these fillings affect several physico‐chemical soil properties, for instance the cation exchange capacity. Although many studies have been conducted on formation, occurrence, and properties of HIMs in soil during the last decades, several challenges still exist. These challenges include analytical identification and quantification of HIMs in soil, the nature of the interlayer filling and the identification of favorable conditions in soil for the formation of HIMs. In order to deepen the understanding of formation, properties, and fate of HIMs in soil, we critically reviewed the available literature. Based on the review, we recommend using a new structural model that enables quantification of hydroxy‐interlayered smectite in soil by X‐ray diffractometry, laboratory experiments on the formation and preservation of different types of interlayers and considering the temporal and spatial dimension of the formation of HIMs in soil in more detail.     

Bioavailability of β-cryptoxanthin in the presence of phytosterols: in vitro and in vivo studies

Bioactive compounds are used in the design and development of new food products with potential health benefits, although little is known regarding their bioavailability and interactions. This study assessed the stability, in vitro bioaccessibility, and human bioavailability of β-cryptoxanthin from β-cryptoxanthin-rich drinks with and without added phytosterols developed for this purpose. The developed drinks showed no difference in the content of β-cryptoxanthin, and they were stable over 6 months. In vitro, hydrolysis of β-cryptoxanthin esters and the amount of free β-cryptoxanthin at duodenal and micellar phases were similar regardless of the presence of phytosterols. In the human study, the daily intake provoked significant increments of β-cryptoxanthin in serum regardless of the type of the drink. In conclusion, in vitro and in vivo human studies have shown that the bioavailability of β-cryptoxanthin is not significantly affected by the presence of phytosterols when they are simultaneously supplied in a drink.     

The content of microelements and iron in soils and plants in the basin of lake Kotokel’ in Western Transbaikalia

The content of microelements (Mn, Zn, Cu, Co, Ni, Cr, Pb, and Cd) and Fe is determined in the soils and plants of the Lake Kotokel’ basin. Their content in the soils is proved not to exceed the regional background and the existing MPC and APC. The content of Cd is revealed to exceed its clarke value for the world soils, which is related to the natural origin of this element. The concentrations of Mn, Co, and Pb are close to their clarke values, and those of Zn, Cu, Ni, and Cr are lower than their clarkes. The studied soils are specified by the maximal amount of the mobile forms of microelements. The profile distribution of the microelements differs depending on the genetic soil type. For Mn, Zn, and Cu, a significant biogenic accumulation is pronounced in the organic soil horizons. The content of microelements in the aboveground phytomass exceeds the maximal permissible levels for Mn, Co, Cr, and Fe. The intensity of the microelements absorption by the plants varies widely, being specified by the high coefficient of the biological adsorption (except for Fe). Mn, Zn, and Cu are accumulated in the plant phytomass the most intensely.     

Influence of Salinity in the Bioavailability of Zn in Sediments of the Gulf of Cádiz (Spain)

This study assesses the effect of salinity in bioavailability and toxicity of Zn by means of laboratory bioassays by observing contamination in both sediment and water, accumulation of Zn in biological tissues, and histopathological damage in the gills and guts tissues of Ruditapes philippinarum clams, which were exposed to different types of sediments from the Gulf of Cádiz (SW Spain) as well as two dilutions of toxic mud coming from an accidental mining spill. With this objective, the coefficients of distribution (K _D) for Zn between overlying water and sediments were calculated, the histopathological frequencies in the tissues of the gills and guts of clams were determined, and the biota-sediment bioaccumulation factors as well as the bioaccumulation factors were quantified in the different stations. Results showed that the greatest histopathological damages appeared when the salinity values decreased. Statistical results showed that salinity was inversely correlated with histopathological damage (p?<?0.01) for the lesion index for gills. The most outstanding results were observed in the two dilutions of toxic mud (0.3% and 7.9%) at a salinity value of 10. Salinity was inversely correlated with the concentration of Zn in biological tissues (p?<?0.05) and inversely correlated with the concentration of Zn in water and sediment. Zn mobilization to the overlying water is produced when salinity values decrease.