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PubMed2002

Activation of soil respiration and shift of the microbial population balance in soil as a response to Lavandula stoechas essential oil.

Lavandula stoechas, a native plant of Greece, is rich in essential oil and fenchone is its major constituent. We examined the effect of the essential oil and its main constituents on soil metabolism and microbial growth. Addition of the essential oil or fenchone to soil samples induced a remarkable increase in soil respiration. This was accompanied by an increase in the soil bacterial population of three orders of magnitude. This sizable population was not qualitatively similar to that of the control soil samples. One bacterial strain dominated soil samples treated with L. stoechas essential oil or fenchone. By use of the disk diffusion assay, we evaluated the capacity of three bacterial strains that we isolated from the soil samples, as well as Escherichia coli and Bacillus subtilis (reference strains), to grow in the presence of the essential oil and three of its main constituents (fenchone, cineol, alpha-pinene). The substances tested did not inhibit the growth of the strain found to dominate the bacterial populations of treated soil samples; they severely inhibited B. subtilis. The other two isolated strains could also grow in liquid cultures in the presence of different quantities of essential oil or fenchone. Addition of fenchone at the end of the exponential phase increased the cell numbers of the strain that dominated the bacterial populations of treated soil samples, indicating use of the substrate added. On the basis of these results, we propose a scheme of successional stages during the decomposition process of the rich-in-essential-oil litter of aromatic plants that abound in the Mediterranean environment.

Aeromonas hydrophila↗
PubMed2003

Microwave-assisted solvent extraction of the herbicide methabenzthiazuron from soils and some soil natural organic and inorganic constituents. Influence of environmental factors on its extractability.

A microwave-assisted solvent extraction (MASE) method for the determination of methabenzthiazuron (MBT) in soil samples by HPLC-DAD (diode array detection) was evaluated. Spiked soil samples having different physico-chemical properties, and selected soil-derived matrices with diverse MBT adsorption capacity, characterized by their Freundlich equation Kf values, were used to verify the method applicability to a broad range of different soils. The spiking procedure was considered a crucial point to reproduce as closely as possible the solute-soil adsorption taking place in the natural environment. Ageing effects, where the compound could diffuse into inaccessible locations within the soil matrix in view of its great stability, were considered of particular concern. In spite of the heterogeneous physico-chemical properties of soils under study, recoveries were greater than 90%. Performance of the MASE procedure correlated highly with the adsorption capacity of soil-derived matrices: the lowest recoveries were for illite (67-73%), among the mineral surfaces, and for a humic acid (67-72%), among the organic fractions. Intra-assay variation for each type of sample soil range from 0.40 to 3.89%(RSD). Limits of detection and quantification were 0.047 and 0.15 microg g(-1), respectively. Analyte residence time was not a very significant factor on the extractability.

Benzothiazoles↗
PubMed2005

Extraction behavior of metallic contaminants and soil constituents from contaminated soils.

With an aim of developing an effective remediation technology for soils contaminated by heavy metals and metalloids, the extraction behavior of metallic contaminants as well as those of soil constituents was studied on a laboratory scale. Three contaminated soils collected from a former metal recycling plant were examined. These three soils were found to be contaminated by As, Cu, Pb, Sb, Se and Zn as compared to the non-contaminated soil. The pH-dependent extraction behavior of various elements from the soils was measured in a wide pH range and categorized into three groups. Hydrochloric acid (HCl), H2SO4, H3PO4, HNO3, sodium citrate, sodium tartrate, disodium dihydrogen ethylenediaminetetraacetate and diethylenetriaminepentaacetic acid were evaluated as extractants for removing contaminants from the soils. Extraction behavior of the soil constituents was also studied. The efficiency of the extraction was evaluated by the Japanese content and leaching tests. The stabilization of Pb remaining in the soil after the extraction process was conducted by the addition of iron(III) and calcium chloride.

Hydrogen-Ion Concentration↗
PubMedDate not supplied

Identifying soil cleanup criteria for dioxins in urban residential soils: how have 20 years of research and risk assessment experience affected the analysis?

This article reviews the scientific evidence and methodologies that have been used to assess the risks posed by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and presents a probabilistic analysis for identifying virtually safe concentrations of TCDD toxicity equivalents (TEQ) in residential soils. Updated data distributions that consider state-of-the-science cancer and noncancer toxicity criteria, child soil ingestion and dermal uptake, bioavailability in soil, and residential exposure duration are incorporated. The probabilistic analysis shows that the most sensitive determinants of dose and risk are childhood soil ingestion, exposure duration, and the selected TCDD cancer potency factor. It also shows that the cancer risk at 1 per 100,000 predicted more conservative (lower) soil criteria values than did the noncancer hazard (e.g., developmental and reproductive effects). In this analysis, acceptable or tolerable soil dioxin concentrations (TCDD TEQ) ranged from 0.4 to 5.5 ppb at the 95th percentile for cancer potency factors from 9600 to 156,000 (mg/kg/d)(-1) with site-specific adjustments not included. Various possible soil guidelines based on cancer and noncancer risks are presented and discussed. In the main, the current toxicology, epidemiology, and exposure assessment data indicate that the historical 1 ppb TEQ soil guidance value remains a reasonable screening value for most residential sites. This analysis provides risk managers with a thorough and transparent methodology, as well as a comprehensive information base, for making informed decisions about selecting soil cleanup values for PCDD/Fs in urban residential settings.

Biological Availability↗
PubMed1980

Effects of environmental variables and soil characteristics on virus survival in soil.

Because of the increasing emphasis placed upon land application as a means of wastewater disposal, it is important to evaluate the influences of different factors upon virus survival in soil. The objective of this study was to measure the effects of various environmental variables on virus persistence. Test samples of soil were placed in vials, and the soil was wetted with suspensions of virus in either distilled water, unchlorinated secondary sewage effluent, or mixtures of effluent and water. The viruses used were coxsackieviruses A9 and B3, echovirus 1, poliovirus 2, rotavirus SA11, and bacteriophages T2 and MS2. The rate of virus inactivation was evaluated statistically with regard to conditions under which the vials were incubated and to the soil characteristics. The factors that were found to influence virus survival were temperature, soil moisture content, presence of aerobic microorganisms, degree of virus adsorption to the soil, soil levels of resin-extractable phosphorus, exchangeable aluminium, and soil pH. Overall, temperature and virus adsorption to soil appeared to be the most important factors affecting virus survival.

Adsorption↗
PubMed1999

Soil bacterial community shift correlated with change from forest to pasture vegetation in a tropical soil.

The change in vegetative cover of a Hawaiian soil from forest to pasture led to significant changes in the composition of the soil bacterial community. DNAs were extracted from both soil habitats and compared for the abundance of guanine-plus-cytosine (G+C) content, by analysis of abundance of phylotypes of small-subunit ribosomal DNA (SSU rDNA) amplified from fractions with 63 and 35% G+C contents, and by phylogenetic analysis of the dominant rDNA clones in the 63% G+C content fraction. All three methods showed differences between the forest and pasture habitats, providing evidence that vegetation had a strong influence on microbial community composition at three levels of taxon resolution. The forest soil DNA had a peak in G+C content of 61%, while the DNA of the pasture soil had a peak in G+C content of 67%. None of the dominant phylotypes found in the forest soil were detected in the pasture soil. For the 63% G+C fraction SSU rDNA sequence analysis of the three most dominant members revealed that their phyla changed from Fibrobacter and Syntrophomonas assemblages in the forest soil to Burkholderia and Rhizobium-Agrobacterium assemblages in the pasture soil.

Agriculture↗
PubMed1991

Evidence of soil-pica behaviour and quantification of soil ingested.

A previously published report on soil ingestion in children, revealed evidence that one of the subjects, a 3.5-year-old female, displayed soil-pica behaviour. Soil ingestion estimates for this child ranged from approximately 5 to 7 g d-1 for seven of eight soil tracers employed. The present paper revealed that the soil-pica behaviour occurred only in the second of the two weeks of observation, during which daily soil ingestion rates ranged from 10 to 13 g d-1. Tracer recovery studies displayed acceptable precision (i.e. 100% less than +/- 30%) for six of the eight tracers during the soil-pica episode (week 2). Evaluation of the weekly soil ingestion values of the remaining 63 subjects indicated no convincing evidence of soil-pica behaviour in this group of children aged 1-4.

Child Behavior↗
PubMed2004

Preparation of artificially spiked soil with polycyclic aromatic hydrocarbons for soil pollution analysis.

To confirm the method for preparing artificially spiked soil with polycyclic aromatic hydrocarbons (PAHs), we tested the homogeneity of PAHs in spiked soils, which were prepared by three different procedures, by using kaolin and ando soil. When the slurry of kaolin and acetone containing PAHs were evaporated by a rotary evaporator at 30 - 35 degrees C, the most homogeneous distribution of PAHs was obtained in the spiked soil. This procedure was applied to the preparation of PAH-spiked soil for natural soil (ando soil). Such spiked soils can be useful as the standard materials for standardization of the analytical methods for PAHs in the soil and sediment samples.

Polycyclic Compounds↗
PubMedDate not supplied

Soil-to-root transfer and translocation of polycyclic aromatic hydrocarbons by vegetables grown on industrial contaminated soils.

Polycyclic aromatic hydrocarbons (PAHs) are possible contaminants in some former industrial sites, representing a potential risk to human health if these sites are converted to residential areas. This work was conducted to determine whether PAHs present in contaminated soils are transferred to edible parts of selected vegetables. Soils were sampled from a former gasworks and a private garden, exhibiting a range of PAH concentrations (4 to 53 to 172 to 1263 and 2526 mg PAHs kg-1 of dry soil), and pot experiments were conducted in a greenhouse with lettuce (Lactuca sativa L. var. Reine de Mai), potato (Solanum tuberosum L. var. Belle de Fontenay), and carrot (Daucus carota L. var. Nantaise). At harvest, above- and below ground biomass were determined and the PAH concentrations in soil were measured. In parallel, plates were placed in the greenhouse to estimate the average PAH-dust deposition. Results showed that the presence of PAHs in soils had no detrimental effect on plant growth. Polycyclic aromatic hydrocarbons were detected in all plants grown in contaminated soils. However, their concentration was low compared with the initial soil concentration, and the bioconcentration factors were low (i.e., ranging from 13.4 x 10(-4) in potato and carrot pulp to 2 x 10(-2) in potato and carrot leaves). Except in peeled potatoes, the PAH concentration in vegetables increased with the PAH concentration in soils. The PAH distribution profiles in plant tissues and in soils suggested that root uptake was the main pathway for high molecular weight PAHs. On the opposite, lower molecular weight PAHs were probably taken up from the atmosphere through the leaves as well as by roots.

Daucus carota↗
PubMed2005

The role of soil chemistry in wine grape quality and sustainable soil management in vineyards.

Abstract This study aimed to establish if there is any evidence that soil mineralogical and/or chemical composition influence the composition and quality of wine grapes. In the initial phase of the study, soils and grapes were sampled in two riesling vineyards in South Australia. Soils were analysed for a wide range of total major and trace elements; soil cation extracts and grape juices were analysed for 27 trace elements by ICP-MS and ICP-AES. The results show that grape juice properties such as Baumé and titratable acidity (TA) are clearly correlated with several plant-available trace elements in the soil. Most notable of these are Ca, Sr, Ba, Pb and Si. Soil clay content also plays a (lesser) role. The cations Ca, Sr, Ba and Pb are closely similar to one another in their relationships to Baumé and TA, strongly indicating that the correlations are real. It is evident from our results that soil cation chemistry does indeed have an influence on wine grape composition. Such knowledge has the potential to be used in better tailoring grape varieties to soils, and in managing--or modifying--soils for optimum viticultural results and better wines in a more sustainable way.

Agriculture↗
PubMed1983

[Behavior of benzo(a)pyrene in the soil and passage from soil to crops].

The behaviour of Benzo[a]pyren (BaP) in the soil and its passage from the soil into the crops has been investigated by means of model tests. In situ fluorescence spectroscopy enables a detection of 0.01 micrograms/BaP/kg with recoveries ranged from 75 to 99.6% and an average variation coefficient of 15%. A decomposition of BaP in test soils within 18 months from 30 mg/kg to 1.5 mg/kg could be attributed to decomposition by soil bacteria. After addition of bactericidal substances to the soil there was no decomposition for several years. In soils with concentrations below 1000 micrograms BaP/kg no passage of BaP into the crops can be detected. Contrary to the opinion of several authors that BaP does not pass from the soil into the crops, model tests conducted for a few years show that a relevant passage into crops such as carrots and radish, as well as into lettuce, spinach and parsley, is possible. The passage into potatoes, tomatoes, peas, and beans is less significant. The degree of contamination of crops is in a certain relation to the degree of the contamination of the soils, but this has only been found with a BaP content of more than 1000 micrograms/kg. Sandy soils which significantly exceed the BaP content of about 1000 micrograms/kg, as they may occur in industrial areas, above all near emittents, are not suitable for the cultivation of some vegetables, such as lettuce and carrots, for human nutrition.

Benzo(a)pyrene↗
PubMed2006

Impact of river overflowing on trace element contamination of volcanic soils in south Italy: part II. Soil biological and biochemical properties in relation to trace element speciation.

The effect of heavy metal contamination on biological and biochemical properties of Italian volcanic soils was evaluated in a multidisciplinary study, involving pedoenvironmental, micromorphological, physical, chemical, biological and biochemical analyses. Soils affected by recurring river overflowing, with Cr(III)-contaminated water and sediments, and a non-flooded control soil were analysed for microbial biomass, total and active fungal mycelium, enzyme activities (i.e., FDA hydrolase, dehydrogenase, beta-glucosidase, urease, arylsulphatase, acid phosphatase) and bacterial diversity (DGGE characterisation). Biological and biochemical data were related with both total and selected fractions of Cr and Cu (the latter deriving from agricultural chemical products) as well as with total and extractable organic C. The growth and activity of soil microbial community were influenced by soil organic C content rather than Cu or Cr contents. In fact, positive correlations between all studied parameters and organic C content were found. On the contrary, negative correlations were observed only between total fungal mycelium, dehydrogenase, arylsulphatase and acid phosphatase activities and only one Cr fraction (the soluble, exchangeable and carbonate bound). However, total Cr content negatively affected the eubacterial diversity but it did not determine changes in soil activity, probably because of the redundancy of functions within species of soil microbial community. On the other hand, expressing biological and biochemical parameters per unit of total organic C, Cu pollution negatively influenced microbial biomass, fungal mycelium and several enzyme activities, confirming soil organic matter is able to mask the negative effects of Cu on microbial community.

Bacteria↗