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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 < 0.001, R² = 0.81). The translocation factor (TF, Cshoot/Croot) of BDE-209 was inversely related to its concentration in roots. Nineteen lower brominated (di- to nona-) 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 < 0.05, R² = 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. [ABSTRACT FROM AUTHOR]

Gut microbiota make an important contribution to host health but the effects of environmental pressures on the gut microbiota of soil fauna are largely uncharacterized. Here, we examine the effects of norfloxacin and oxytetracycline on the gut microbiome of the common soil collembolan Folsomia candida and concomitant changes in the incidence of antibiotic resistance genes (ARGs) in the gut and in growth of the collembolan. Exposure to 10 mg antibiotics kg-1 for 2 weeks significantly inhibited the growth of the collembolan with roughly a 10-fold decrease in 16S rRNA gene abundance. Antibiotics did alter the composition and structure of the collembolan gut microbiome and decreased the diversity of the gut bacteria. A decline in the firmicutes/bacteroidetes ratio in the antibiotic-treated collembolans may be responsible for the decrease in body weight. Exposure to antibiotics significantly increased the diversity and abundance of ARGs in the collembolan gut. The Mantel test and Procrustes analysis both reveal that ARGs and gut microbiota were significantly correlated with one another (P < 0.05). These results indicate that antibiotics may induce a shift in the gut microbiota of nontarget organisms such as soil collembolans and thereby affect their growth and enrichment of ARGs. [ABSTRACT FROM AUTHOR]

The authors discuss the development of technology in China that will allow for the recovery of shale gas reserves through the practice of hydraulic fracturing, or hydrofracking. They address the reserves of China's shale gas as it compares to China's annual gas consumption Other topics explored include the use of shale gas as a near-term energy strategy in developing economies, the improvement of China's energy distribution infrastructure, and the rapidly increasing energy demand in China.

Adsorption by minerals is a common geochemical process of dissolved organic matter (DOM) which may induce fractionation of DOM at the mineral-water interface. Here, we examine the molecular fractionation of DOM induced by adsorption onto three common iron oxyhydroxides using electrospray ionization coupled with Fouriertransform ion cyclotron resonance mass spectrometry (ESI-FT-ICRMS). Ferrihydrite exhibited higher affinity to DOM and induced more pronounced molecular fractionation of DOM than did goethite or lepidocrocite. High molecular weight (>500 Da) compounds and compounds high in unsaturation or rich in oxygen including polycyclic aromatics, polyphenols and carboxylic compounds had higher affinity to iron oxyhydroxides and especially to ferrihydrite. Low molecular weight compounds and compounds low in unsaturation or containing few oxygenated groups (mainly alcohols and ethers) were preferentially maintained in solution. This study confirms that the double bond equivalence and the number of oxygen atoms are valuable parameters indicating the selective fractionation of DOM at mineral and water interfaces. The results of this study provide important information for further understanding the behavior of DOM in the natural environment. [ABSTRACT FROM AUTHOR]

The toxicity and fate of nanoparticles (NPs) have been reported to be highly dependent on the chemistry of the medium, and the effects of phosphate have tended to be ignored despite the wide existence of phosphate contamination in aqueous environments. In the present study the influence of phosphate on the dissolution and microstructural transformation of ZnO NPs was investigated. Phosphate at a low concentration rapidly and substantially reduced the release of Zn2+ into aqueous solution. Synchrotron X-ray absorption spectroscopy and X-ray diffraction analysis reveal that interaction between ZnO NPs and phosphate induced the transformation of ZnO into zinc phosphate. Transmission electronic microscopy observation shows that the morphology of the particles changed from structurally uniform nanosized spherical to anomalous and porous material containing mixed amorphous and crystalline phases of ZnO and zinc phosphate in the presence of phosphate. To our knowledge, this is the first study in which the detailed process of phosphate-induced speciation and microstructural transformation of ZnO NPs has been analyzed. In view of the wide existence of phosphate contamination in water and its strong metal-complexation capability, phosphate-induced transformations may play an important role in the behaviors, fate, and toxicity of many other metal-based nanomaterials in the environment. [ABSTRACT FROM AUTHOR]

A new type of composite membrane is introduced to mimic plant uptake of hydrophobic organic contaminants (HOCs). Petroselinic acid (cio-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) naphtholene (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 Kpw, 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 (R² = 0.995) and were almost the same as the lipid-normalized root partition coefficients (log Klip) for the corresponding compounds. Their relationship can be expressed as log Kpw = 0.98 log Klip. The normalized plant uptake coefficients (log Ku) obtained by in vivo experiments with a range of plant species (2.92, 4.43, 5.06, and 6.13 on overage for Nap, Phe, Pyr, and Bap, respectively) were slightly lower than those of the log Kpw 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. [ABSTRACT FROM AUTHOR]

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. PAH 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, μg g-1 root/μg g-1 soil on dry weight basis) and log Kow 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 Kow varying from 3.45 to 5.78) was also implicated by Rt (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 Rt and log Kow of these PAHs (p < 0.01), and acropetal translocation of PAHs depended on their chemical properties. [ABSTRACT FROM AUTHOR]

Effects of metal cations (Na+, Ca2+, and A/3+ on phenanthrene sorption were investigated using two soils with contrasting organic carbon (OC) contents. The presence of the polyvalent cations (i.e., Ca2+ or A/3+) at a concentration of 0.01 mol/L significantly increased the capacity and nonlinearity of phenanthrene sorption to soils compared with the monovalent Na+. The effects were governed by the content of soil OC. Rubbery OC (i.e., soft, amorphous OC including dissolved organic carbon (DOC)) tended to become condensed on soil surfaces as evidenced by a decrease in the signals of the ¹H NMR spectra of DOC and an increase in the glass transition temperature (Tg) of the soils when the polyvalent cations were present Increasing Ca2+ concentration led initially to an effect similar to that of the polyvalent cations in the low cation concentration range, and the effect was gradually attenuated as Ca2+ concentration further increased. These findings lead us to propose that the modifications in the physical configuration and chemical characteristics of OC resulting from the presence of metal cations account for the increase in the capacity and nonlinearity of phenanthrene sorption to the soils. This study points to an important role of metal cations in the sorption and fate of phenanthrene in the soil environment. [ABSTRACT FROM AUTHOR]

Equilibrium sorption of phenanthrene and its relationship with plant lipid contents were investigated using roots and shoots of alfalfa, ryegrass, tomato, potato, carrot, cucumber, zucchini, and pumpkin. Lipid extractions using chloroform and hexane were compared, and the influence of dechlorophyllization on lipid determinations was evaluated. The sorption isotherms were close to linear (R2 > 0.923, P < 0.05) and the plant-water partition coefficients (Kpl) of phenanthrene obtained from the isotherms exhibited significant and positive correlations with plant lipid contents (R2> 0.664, P < 0.05). The correlations were more significant (R2 > 0.906, P < 0.001) when dechlorophyllization was included in the lipid extraction. The measured sorption was higher than that estimated using the octanol-water partition coefficient (Kow) but was very close to the estimate using the triolein-water partition coefficient (Ktw). This study leads us to conclude that dechlorophyllization is necessary for plant lipid determination and that Ktw is more accurate as a substitute for the lipid-water partition coefficient (Klip) than Kow. These novel approaches may provide substantial improvements in the application of partition-limited models for the estimation of plant uptake of organic contaminants. [ABSTRACT FROM AUTHOR]