Chitin biodegradation and wound healing in tree bark tissues

Chitin biodegradation and wounded bark tissue healing were demonstrated in several evergreen and deciduous trees by dressing with a sheet of chitin-containing films or sponges. Chitinase activities in the tree bark tissues around the wounds were enhanced by this treatment up to four times those of the untreated wounds. Significant seasonal changes of chitinase activities were observed with the bark and leaf tissues of deciduous trees, but few with those of evergreen trees. A sheet of chitin films implanted or dressed in the tree bark tissues was biodegraded within 4 to 24 weeks after implantation and was assimilated into the wounded bark tissues, resulting in the stimulation of the wounded bark tissue healing.     

Polychlorinated dibenzo-p-dioxins and dibenzofurans in invertebrate animals from a rural beach in Japan

PCDDs and PCDFs were analyzed by high resolution GC MS in several invertebrate animals collected from a rural beach in Japan. PCDDs and PCDFs were detected in all samples. Total concentration of PCDDs and PCDFs ranged 8.8–120 pg g⁻¹ wet and 3.5–38 pg g⁻¹ wet, respectively. TEQs of invertebrate animals examined ranged from 0.048 pg g⁻¹ wet in sea slug to 0.91 pg g⁻¹ wet in mussel. Isomer profiles in all samples were similar to each other despite of variety of species. Their major sources are estimated to be herbicides such as CNP and PCP, and combustion by using a statistical analysis of isomer profiles.     

Toxicity and metabolism of copper pyrithione and its degradation product, 2,2'-dipyridyldisulfide in a marine polychaete

We conducted acute toxicity tests and sediment toxicity tests for copper pyrithione (CuPT) and a metal pyrithione degradation product, 2,2′-dipyridyldisulfide [(PS)₂], using a marine polychaete Perinereis nuntia. The acute toxicity tests yielded 14-d LC₅₀ concentrations for CuPT and (PS)₂ of 0.06 mg L⁻¹ and 7.9 mg L⁻¹, respectively. Sediment toxicity tests resulted in 14-d LC₅₀ concentrations for CuPT and (PS)₂ of 1.1 mg kg⁻¹ dry wt. and 14 mg kg⁻¹ dry wt., respectively. In addition to mortality, sediment avoidance behavior and decreases in animal growth rate were observed; growth rate was the most susceptible endpoint in the sediment toxicity tests of both toxicants. Thus, we propose lowest observed effect concentrations of 0.3 mg kg⁻¹ dry wt. and 0.2 mg kg⁻¹ dry wt. for CuPT and (PS)₂, respectively, and no observed effect concentrations of 0.1 mg kg⁻¹ dry wt. for both CuPT and (PS)₂. The difference in the toxicity values between CuPT and (PS)₂ observed in the acute toxicity test was greater than the difference in these values in the sediment toxicity test, and we attribute this to (PS)₂ being more hydrophilic than CuPT. In addition to the toxicity tests, we analyzed conjugation activity of several polychaete enzymes to the toxicants and marked activity of palmitoyl coenzyme-A:biocides acyltransferase and UDP-glucuronosyl transferase was observed.     

Sorption of dissolved lead from shooting range soils using hydroxyapatite amendments synthesized from industrial byproducts as affected by varying pH conditions

For immobilization technologies to be successful, the use of readily available and cost advantageous amendment is important when the remediation targets vast amounts of contaminated soils. The objectives of this study were to investigate whether the byproduct-synthesized hydroxyapatite can be used as an immobilizing amendment for dissolved Pb from a shooting range soil, and to model the kinetic data collected from dissolution experiments. A soil–solution kinetic experiment was conducted under fixed pH conditions as a function of time. A Pb-contaminated soil was reacted with various hydroxyapatite amendments to determine the dissolution rate and mineral products of soil Pb. Three types of amendments used were pure hydroxyapatite (HA), and poorly crystalline hydroxyapatites synthesized from gypsum waste (CHA), and synthesized from incinerated poultry litter (PHA). The dissolved Pb concentration decreased with the addition of amendments at pH 3–7. Both CHA and PHA were more effective than HA for attenuating Pb dissolution at pH 6 and above. According to the thermodynamic calculation at pH 6, the dissolved Pb concentration for CHA and PHA treatments was predicted to be 66% and 50% lower than that of HA treatment, respectively. A better Pb immobilization effect demonstrated by CHA and PHA resulted in their greater solubility at higher pH, which may promote the formation of chloropyromorphite precipitates. Dissolution kinetics of soil Pb was adequately explained by pseudo-first order and pseudo-second order equations in acid pH ranges. According to the ion exchange model, an adequate agreement between the experimental data and regression curves was shown in the initial 40 min of the reaction process, but the accuracy of model predictability decreased thereafter. According to kinetic models and dissolution phenomena, CHA and PHA amendments had better Pb sorption capacity with rapid kinetics than pure hydroxyapatite at weak acid to neutral pH.     

Degradation pathways of decabromodiphenyl ether during hydrothermal treatment

The hydrothermal degradation pathways of decabromodiphenyl ether during hydrothermal treatment were investigated. After an initial "Heating time", the reaction runs were carried out at constant temperature (heating to 300 degrees C and keeping temperature) and pressure (8MPa) in a SUS316 stainless steel micro autoclave filled with water. Some decomposition of decabromodiphenyl ether was observed over 200 degrees C, and it was decomposed by more than 99% after 10 min at 300 degrees C. The reactivities of bromine on para and meta substituents were relatively high, while its reactivity on ortho bromine was extremely low. The formations of polybrominated dibenzo-p-dioxins and furans (PBDD/DFs) were observed in the early stages of the reactions at around 300 degrees C. The TCDD toxicity equivalency (TCDD-EQs) of the by-products was determined based on relative potencies (REPs EC(5TCDD)) with the Dioxin-Responsive-Chemical Activated Luciferase gene eXpression (DR-CALUX) bioassays technology. These results indicated that the risk of formation of PBDD/DFs in the hydrothermal degradation of deca-BDE was low, and it would be possible to reduce the TCDD-EQs value by adding some catalyst or alkali, or extending processing time.     

Attenuation of lead leachability in shooting range soils using poultry waste amendments in combination with indigenous plant species

Chemical immobilization technology utilizing poultry waste (PW) along with a native plant (Panicum maximum Jacq.) application was assessed for the attenuation of downward Pb dissolution and modification of Pb speciation in solid and liquid phases in the soil. A large column study with and without plant and PW applications was conducted using a Pb contaminated soil collected from a shooting range area. The PW application reduced water-extractable Pb by about 43% of that of the treatment without the PW and plant applications (Control). The cumulative Pb amount in column leachates over 100d was increased by the PW amendment (0.32mg) compared to Control (0.27mg), but was reduced to 0.23mg by the combined use of plant and PW amendment. Sequential extraction analysis revealed that the Pb fractions of PW-amended soils were shifted to less soluble phases as indicated by an increased residual fraction (20%) and decreased exchangeable and carbonate fractions (22%) than those in the Control soil. Thermodynamic equilibrium calculations demonstrated that predicted Pb(2+) activity was saturated with respect to cerussite in the Control soil and was supersaturated with respect to chloropyromorphite in the PW-amended soils. Our results suggest that the use of plant in combination with PW as a Pb immobilizing amendment attenuated downward Pb leaching and altered Pb species to more geochemically stable phases.     

Differences in the Spatial Variability Among CO2, CH4, and N2O Gas Fluxes from an Urban Forest Soil in Japan

The spatial variability of carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O) fluxes from forest soil with high nitrogen (N) deposition was investigated at a rolling hill region in Japan. Gas fluxes were measured on July 25th and December 5th, 2008 at 100 points within a 100 × 100 m grid. Slope direction and position influenced soil characteristics and site-specific emissions were found. The CO₂ flux showed no topological difference in July, but was significantly lower in December for north-slope with coniferous trees. Spatial dependency of CH₄ fluxes was stronger than that of CO₂ or N₂O and showed a significantly higher uptake in hill top, and emissions in the valley indicating strong influence of water status. N₂O fluxes showed no spatial dependency and exhibited high hot spots at different topology in July and December. The high N deposition led to high N₂O fluxes and emphasized the spatial variability.     

A new scheme for initializing process-based ecosystem models by scaling soil carbon pools

Process-based ecosystem models are useful tools, not only for understanding the forest carbon cycle, but also for predicting future change. In order to apply a model to simulate a specific time period, model initialization is required. In this study, we propose a new scheme of initialization for forest ecosystem models, which we term a “slow-relaxation scheme”, that entails scaling of the soil carbon and nitrogen pools slowly during the spin-up period. The proposed slow-relation scheme was tested with the CENTURY version 4 ecosystem model. Three different combinations of scaled soil pools were also tested, and compared to the results from a fast-relaxation regime. The fast-relaxation of soil pools produced unstable, transient model behaviour whereas slow-relaxation overcame this instability. This approach holds promise for initializing ecosystem models, and for starting simulations with more realistic initial conditions.     

The influence of environmental deterioration and network improvement on transport modal choice

We consider that transport modal choices are influenced by natural environmental change and transport network improvement. This paper examines how these impacts affect individuals’ decisions on selecting transport mode under an extension plan for the Osaka Monorail Loop-line. To estimate these impacts, we perform a Stated Choice (SC) experiment for collecting data in the neighborhood along the monorail's extended line. We estimate our model with the Heteroskedastic Extreme Value (HEV) specification in order to avoid the Independence of Irrelevant Alternatives (IIA) assumption in the Multinomial Logit (MNL) model. Both the results of full-sample and sub-sample data imply that residents prefer public transport modes (monorail or bus) to private cars when either the natural environment becomes worse or the transport network improves.     

Fungal hydroxylation of polychlorinated naphthalenes with chlorine migration by wood rotting fungi

Biodegradation of the polychlorinated naphthalenes (PCNs) 1,4-dichloronaphthalene (1,4-DCN), 2,7-dichloronaphthalene (2,7-DCN), and 1,2,3,4-tetrachloronaphthalene (1,2,3,4-TCN), by the white-rot fungus Phlebia lindtneri was investigated. 1,4-DCN was metabolized to form six metabolites by the fungus. It was estimated from GC–MS fragment patterns that the metabolites were four putative hydroxylated and two dihydrodihydroxylated compounds. One of the hydroxylated products was identified as 2,4-dichloro-1-naphthol by GC–MS analysis using an authentic standard. This intermediate indicated chlorine migration in a biological system of P. lindtneri. 2,7-DCN was metabolized to five hydroxylated metabolites and a dihydrodihydroxylated metabolite. Significant inhibition of the degradation of DCNs and formation of their metabolic products was observed in incubation with the cytochrome P-450 monooxygenase inhibitor piperonyl butoxide. The formation of the dihydrodiol-like metabolites, chlorine migration and the experiment with P-450 inhibitor suggested that P. lindtneri provides hydroxyl metabolites via benzene oxide intermediates of DCNs by a cytochrome P450 monooxygenase. In addition, P. lindtneri degraded 1,2,3,4-TCN; two hydroxylated compounds and a dihydrodihydroxylated compound were formed.