Predicting bioavailability of PAHs in field-contaminated soils by passive sampling with triolein embedded cellulose acetate membranes

Triolein embedded cellulose acetate membrane (TECAM) was used for passive sampling of the fraction of naphthalene, phenanthrene, pyrene and benzo[a]pyrene in 18 field -contaminated soils. The sampling process of PAHs by TECAM fitted well with a first-order kinetics model and PAHs reached 95% of equilibrium in TECAM within 20 h. Concentrations of PAHs in TECAM (C-TECAM) correlated well with the concentrations in soils (r(2) = 0.693-0.962, p < 0.001). Furthermore. concentrations of PAHs determined in the soil solution were very close to the values estimated by C-TECAM and the partition coefficient between TECAM and water (KTECAM-W). After lipid normalization nearly 1:1 relationships were observed between PAH concentrations in TECAMs and earthworms exposed to the soils (r(2) = 0.591-0.824, n = 18, p < 0.01). These results suggest that TECAM can be a useful tool to predict bioavailability of PAHs in field-contaminated soils. (C) 2008 Elsevier Ltd. All rights reserved

Uptake and acropetal translocation of polycyclic aromatic hydrocarbons by wheat (Triticum aestivum L.) grown in field-contaminated soil

Uptake and acropetal translocation of 14 priority polycyclic aromatic hydrocarbons (PAHs) by wheat (Triticum aestivum L.) grown in 15 field-contaminated soils were investigated in a growth chamber. PAN concentrations in roots correlated positively with the corresponding concentrations in soils and negatively with the contents of soil organic carbon (p < 0.01). No clear linear relationship was found between log RCF (root concentration factor, mu g g(-1)root/mu g g(-1)soil on dry weight basis) and log K(ow) of these PAHs. Four-ring PAHs had the highest tendency to be taken up by roots. PAH concentrations in shoots correlated well with their concentrations in soils and roots. Furthermore, distribution profiles of PAHs in shoots were fairly similar to those in soils. Acropetal translocation of 10 PAHs (with log K(ow) varying from 3.45 to 5.78) was also implicated by R(t) (ratio of PAH from root-to-shoot translocation to the total accumulation in shoots) ranging from 53.6 to 72.6%. A negative linear relationship was found between log R(t) and log K(ow) of these PAHs (p < 0.01), and acropetal translocation of PAHs depended on their chemical properties

Remarks on Hawking radiation as tunneling from the BTZ black holes

Hawking radiation viewed as a semiclassical tunneling process from the event horizon of the (2 + 1)-dimensional rotating BTZ black hole is carefully reexamined by taking into account not only the energy conservation but also the conservation of angular momentum when the effect of the emitted particle's self-gravitation is incorporated. In contrast to previous analysis of this issue in the literature, our result obtained here fits well to the Kraus-Parikh-Wilczek's universal conclusion without any modification to the Bekenstein-Hawking area-entropy formulae of the BTZ black hole.Comment: 12pages, no figure, use JHEP3.cls. Version better than published one in JHE

Behavior of decabromodiphenyl ether (BDE-209) in the soil-plant system: uptake, translocation, and metabolism in plants and dissipation in soil

Deca-bromodiphenyl ether (BDE-209) is the major component of the commercial deca-BDE flame retardant. There is increasing concern over BDE-209 due to its increasing occurrence in the environment and in humans. In this study the behavior of BDE-209 in the soil-plant system was investigated. Accumulation of BDE-209 was observed in the roots and shoots of all the six plant species examined, namely ryegrass, alfalfa, pumpkin, summer squash, maize, and radish. Root uptake of BDE-209 was positively correlated with root lipid content (P &lt; 0.001, R(2) = 0.81). The translocation factor (TF, C(shoot)/C(root)) of BDE-209 was inversely related to its concentration in roots. Nineteen lower brominated (di- to nor a-) PBDEs were detected in the soil and plant samples and five hydroxylated congeners were detected in the plant samples, indicating debromination and hydroxylation of BDE-209 in the soil-plant system. Evidence of a relatively higher proportion of penta- through di-BDE congeners in plant tissues than in the soil indicates that there is further debromination of PBDEs within plants or low brominated PBDEs are more! readily taken up by plants. A significant negative correlation between the residual BDE-209 concentration in soil and the soil microbial biomass measured as the total phospholipid fatty, acids (PLFAs) (P &lt; 0.05, R(2) = 0.74) suggests that microbial metabolism and degradation contribute to BDE-209 dissipation in soil. These results provide important information about the behavior of BDE-209 in the soil-plant system

Influence of Glomus etunicatum/Zea mays mycorrhiza on atrazine degradation, soil phosphatase and dehydrogenase activities, and soil microbial community structure

The effects of an arbuscular mycorrhizal (AM) fungus (Glomus etunicatum) on atrazine dissipation, soil phosphatase and dehydrogenase activities and soil microbial community structure were investigated. A compartmented side-arm (&#39;cross-pot&#39;) system was used for plant cultivation. Maize was cultivated in the main root compartment and atrazine-contaminated soil was added to the side-arms and between them 650 or 37 mu m nylon mesh was inserted which allowed mycorrhizal roots or extraradical mycelium to access atrazine in soil in the side-arms. Mycorrhizal roots and extraradical mycelium increased the degradation of atrazine in soil and modified the soil enzyme activities and total soil phospholipid fatty acids (PLFAs). Atrazine declined more and there was greater stimulation of phosphatase and dehydrogenase activities and total PLFAs in soil in the extraradical mycelium compartment than in the mycorrhizal root compartment when the atrazine addition rate to soil was 5.0 mg kg(-1). Mycelium had a more important influence than mycorrhizal roots on atrazine degradation. However, when the atrazine addition rate was 50.0 mg kg(-1). atrazine declined more in the mycorrhizal root compartment than in the extraradical mycelium compartment, perhaps due to inhibition of bacterial activity and higher toxicity to AM mycelium by atrazine at higher concentration. Soil PLFA profiles indicated that the AM fungus exerted a pronounced effect on soil microbial community structure. (C) 2009 Elsevier Ltd. All rights reserved

Using a novel petroselinic acid embedded cellulose acetate membrane to mimic plant partitioning and in vivo uptake of polycyclic aromatic hydrocarbons

A new type of composite membrane is introduced to mimic plant uptake of hydrophobic organic contaminants (HOCs). Petroselinic acid (cis-6-octadecenoic acid),the major component of plant lipids, was embedded in the matrix of cellulose acetate polymer to form the petroselinic acid embedded cellulose acetate membrane (PECAM). Accumulation of the polycyclic aromatic hydrocarbons (PAHs) naphthalene (Nap), phenanthrene (Phe), pyrene (Pyr), and benz(a)pyrene (Bap) by PECAM was compared with their uptake by plants. The accumulation of Nap, Phe, Pyr, and Bap by PECAM reached equilibrium in 24,48,144, and 192 h, respectively. The petroselinic acid-water partition coefficients (log K(pw), 3.37, 4.90, 5.24, and 6.28 for Nap, Phe, Pyr, and Bap, respectively) were positively correlated with the hydrophobicity of the compounds (R(2) = 0.995) and were almost the same as the lipid-normalized root partition coefficients (log K(lip)) for the corresponding compounds. Their relationship can be expressed as log K(pw) = 0.98 log K(lip). The normalized plant uptake coefficients (log K(u)) obtained by in vivo experiments with a range of plant species (2.92, 4.43, 5.06, and 6.13 on average for Nap, Phe, Pyr, and Bap, respectively) were slightly lower than those of the log K(pw) values for the corresponding compounds, presumably due to their acropetal translocation and biodegradation inside plants. This work suggests that PECAMs can well mimic plant partitioning and in vivo uptake of PAHs and may have good potential as a nonliving accumulator to mimic plant uptake of PAHs and perhaps other HOCs

Partitioning of phenanthrene by root cell walls and cell wall fractions of wheat (Triticum aestivum L.)

Plant cells have been reported to play an important role in the uptake of organic contaminants. This study was undertaken to provide an insight into the role of the root cell walls and their subfractions on sorption of phenanthrene to roots of wheat (Triticum aestivum L.). Root cell walls were isolated and further sequentially fractioned by removing pectin, hemicellulose one, and hemicellulose two. They were characterized by elemental analysis, Fourier transform infrared spectroscopy, and solid-state (13)C NMR. Root cell walls had a greater proportion of aromatic carbon and exhibited a lower polarity than the bulk roots. There was a stepwise increase in aromatic carbon content and a decrease in polarity following the sequential fractionation. The sorption affinity of phenanthrene increased gradually following the sequential extraction of root cells. A significant positive correlation between the sorption affinity K(OC) values and the aromatic carbon contents (r(2) = 0.896, p &lt; 0.01) and a negative correlation between the sorption affinity K(OC) values and polarity ((O + N)/C) of root cell fractions (r(2) = 0.920, p &lt; 0.01) were obtained. Improved modeling was achieved for phenanthrene sorption by involving the contribution of root cell walls as a source of root carbohydrates instead of using root lipids alone, which further confirms the significant contribution of root cell walls to phenanthrene sorption on wheat roots. The results provide evidence for the importance of the root cell walls in the partitioning of phenanthrene by plant roots

Identification of rice chromosome segment substitution line Z322-1-10 and mapping QTLs for agronomic traits from the F₃ population

Chromosome segment substitution lines (CSSLs) are powerful tools to combine naturally occurring genetic variants with favorable alleles in the same genetic backgrounds of elite cultivars. An elite CSSL Z322-1-10 was identified from advanced backcrosses between a japonica cultivar Nipponbare and an elite indica restorer Xihui 18 by SSR marker-assisted selection (MAS). The Z322-1-10 line carries five substitution segments distributed on chromosomes 1, 2, 5, 6 and 10 with an average length of 4.80 Mb. Spikilets per panicle, 1000-grain weight, grain length in the Z322-1-10 line are significantly higher than those in Nipponbare. Quantitative trait loci (QTLs) were identified and mapped for nine agronomic traits in an F3 population derived from the cross between Nipponbare and Z322-1-10 using the restricted maximum likelihood (REML) method in the HPMIXED procedure of SAS. We detected 13 QTLs whose effect ranging from 2.45% to 44.17% in terms of phenotypic variance explained. Of the 13 loci detected, three are major QTL (qGL1, qGW5-1 and qRLW5-1) and they explain 34.68%, 44.17% and 33.05% of the phenotypic variance. The qGL1 locus controls grain length with a typical Mendelian dominance inheritance of 3:1 ratio for long grain to short grain. The already cloned QTL qGW5-1 is linked with a minor QTL for grain width qGW5-2 (13.01%) in the same substitution segment. Similarly, the previously reported qRLW5-1 is also linked with a minor QTL qRLW5-2. Not only the study is important for fine mapping and cloning of the gene qGL1, but also has a great potential for molecular breeding