The CH₄ oxidation dynamics was investigated by observing the CH₄ oxidation rates at concentrations (from 1.0 × 10⁴ ppmv to 2.0 × 10⁵ ppmv) mixed with O₂ (from 5.0 × 10⁴ ppmv to 7.5 × 10⁵ ppmv). The CH₄–O₂ dual-substrate model based on Michaelis–Menten equation ( [Formula: see text] = 1.4 × 10⁵ ppmv; Vₘₐₓ = 7.6 × 10² μmol kg⁻¹ d⁻¹; [Formula: see text] = 5.5 × 10⁴ ppmv) was got and agreed well with the experimental data when the initial O₂/CH₄ ratio reached 3:1, indicating full aerobic CH₄ oxidization. Anoxic CH₄ oxidation gradually became predominant with decreasing O₂/CH₄ ratios. The effect of CH₄ is more significant than O₂, as evidenced by higher slope (0.58 kg⁻¹ d⁻¹) of [Formula: see text] line graph compared with that of [Formula: see text] line graph (0.062 kg⁻¹ d⁻¹). The paper presents the dynamics of CH₄ oxidation and proposes that ratio of O₂/CH₄ need to be considered for their dynamically changing in environmental habitats. The findings provide an important parameter for optimizing the operations of breathing biocover systems.

The occurrence of PBDEs has been studied in the atmosphere of four sites in the United Kingdom over a period of ten years. The concentrations have exhibited a sharp decrease after 2001–2003. This is evident in the urban sites of Manchester and London and at the semi-rural site of Hazelrigg. The average ΣPBDE half-lives for these three sites were 3.4, 2.0 and 3.5 years respectively. ΣPBDEs concentrations in the UK (in 2010 ΣPBDEs < 10 pg m⁻³) are among the lowest reported in literature. Comparison of concentrations to estimated emissions and employment of PBDE profiles suggest that PBDEs in the UK atmosphere originate from primary emissions from products that contain mainly the penta-BDE technical mixture. The detection of BDE-183 in the majority of samples hints that octa-bromodiphenylether has also been used extensively in the UK, however to a smaller extent than the penta- product.

Polybrominated diphenyl ethers (PBDEs) constitute an important group of brominated flame retardants that have been massively produced and extensively used in numerous everyday products, providing longer escape times in case of fire and thus saving lives, as well as reducing the damage of property. In recent years, PBDEs have been recognized as significant pollutants of the indoor environment. This article provides a synthesis and critical evaluation of the state of the knowledge about the occurrence of PBDEs in the indoor environment (air and dust in homes, workplaces and cars) in different countries in Europe, North America, Asia and Australia, as well as about the human exposure via indoor air inhalation and dust ingestion in comparison to outdoor air inhalation and dietary intake.

There are currently contradicting results in the literature about the way chloroethene (CE) concentrations from tree core sampling correlate with those from groundwater measurements. This paper addresses this issue by focusing on groundwater and tree core datasets in CE contaminated site, Czech Republic. Preliminary analyses revealed strongly and positively skewed distributions for the tree core dataset, with an intra-tree variability accounting for more than 80% of the total variability, while the spatial analyses based on variograms indicated no obvious spatial pattern for CE concentration. Using rank transformation, it is shown how the results were improved by revealing the initially hidden spatial structure for both variables when they are handled separately. However, bivariate analyses based on cross-covariance functions still failed to indicate a clear spatial correlation between groundwater and tree core measurements. Nonetheless, tree core sampling and analysis proved to be a quick and inexpensive semi-quantitative method and a useful tool.

Surface fire could induce heat transferring into the soil, creating a carbonized environment, which may alter the chemical compositions of soil organic matters (SOM). In the study, a surface soil was carbonized at up to 600 °C with limited air to simulate soils experiencing a surface fire, and Cr(VI) removal on the carbonized soils was investigated. NMR and FTIR analyses demonstrated a remarkable change of SOM structures at 300–400 °C. TGA-MS spectra indicated that (e.g. C₂H₄, CH₃OH and C₃H₈) were the major components in the evolved gases from the pyrolyzed soil. A maximum amount of Cr(VI) removal (ca. 4 mg g⁻¹ soil) occurred for the 200 °C-carbonized soils, attributed mainly to a significant increase of Cr(VI) reduction by 0.1 M KCl extractable organic carbon (EOC) with abundant carboxylic groups. Nonetheless, the formation of aromatic C upon carbonization of the soil at >400 °C may be responsible for Cr(VI) reduction.

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Authors. The authors have informed the Editor and the publisher of the journal that substantial parts of the article need corrections. These corrections are so significant and extensive that the article could no longer be considered to be same as the one originally submitted, reviewed and accepted for publication.

The comparative accumulation of C₄–C₁₅ perfluorinated sulfonates (PFSAs) and carboxylates (PFCAs), and several precursors (e.g., perfluorooctane sulfonamide, N-methyl-FOSA, and fluorotelomer unsaturated acids and alcohols) was examined in tissues (liver, brain, muscle, and adipose), plasma/red blood cells (RBCs) and whole egg clutches (yolk and albumen) of female herring gulls collected in 2010 from Chantry Island, Lake Huron of the Laurentian Great Lakes. Highest mean ∑PFSA concentrations were in yolk, followed by adipose, liver, plasma, muscle, RBCs, and brain. Highest mean ∑PFCA concentrations were in yolk, followed by brain, plasma, liver, RBC, adipose and muscle. PFOS accounted for >88% of ∑PFSA in all samples; the liver, plasma/RBCs, muscle and adipose PFCA patterns were dominated by C₈–C₁₁ PFCAs, whereas C₁₀–C₁₅ PFCAs in brain and yolk. Among PFSAs and PFCAs there is tissue-specific accumulation, which could be due to a number of pharmacokinetic processes.

Triolein embedded cellulose acetate membrane (TECAM) passive samplers provide potentially powerful tool for monitoring time weighted average concentrations (CTWA) of trace hydrophobic organic contaminants in water. To study the field performance of TECAM, exchange kinetics of chemicals between water and TECAM were studied at different temperature and water flow rates. Results showed that the uptake rate constant (kᵤ) in TECAM was less sensitive to temperature variation than the SPMD and Chemcatcher. The kᵤ in TECAM was sensitive to even a slight change of the flow rate, which required the field calibration using performance reference compounds (PRCs). To estimate CTWA by TECAM, both empirical model and WBL model were compared in laboratory conditions, and only small differences were observed between the predicted and measured kᵤ. Field validation was conducted to test the sampler performance alongside spot sampling. A good agreement of water concentration was obtained by the two sampling techniques.

Solubilization of particulate Cu by different solutions, mimicking digestive fluids of deposit-feeders, was quantified in stable isotope ⁶⁵Cu-spiked sediments (with 3 days-2 months Cu-sediment contact time or aging). Copper solubilization generally decreased with prolonged aging. However, such decrease became less evident after 1 month and equilibrium of Cu in sediments could be reached after 2 months. Aging effects on Cu solubilization can be explained by the changes in Cu geochemical fractionation with aging: Cu generally transferred from more mobile phases (carbonate and Fe–Mn associated) to more refractory phases (organic associated and residual phase). Besides Cu geochemical fractionation, digestive fluid composition and different Cu solubilization pathways involved, as well as sedimentary organic content, could all affect the digestive solubilization of Cu and its change with aging. Our results emphasize the necessity of considering Cu aging in laboratory sediment toxicity experiments, and in risk assessment of Cu contaminated sediments.

One concern about the chelant-enhanced phytoextraction is the potential metal leaching associated with chelant application. A field study was carried out and the metal leaching along the 60-cm depth soil profiles were evaluated within 36 days after the biodegradable chelant EDDS was applied. Results showed EDDS significantly increased soluble Cu in the top 5 cm soil layer 1 day after the application, and the increase of soluble metals was generally limited in the top 20 cm soil. Metal speciation analysis indicated all Cu and Zn were in forms of Cu-EDDS and Zn-EDDS complexes in soil solution, and Ca was the major competitor with trace metals to EDDS. The soluble metals decreased quickly with time, and no significant difference was observed in the extractable Cu between EDDS treatments and the controls 22 days after the EDDS addition. The potential leaching associated with biodegradable EDDS addition may be controlled under field conditions.