Correlating the Spatial Distribution of Atmospheric Ammonia with δ15N Values at an Ammonia Release Site

A field ammonia (NH₃) release experiment and open top chambers containing moorland monoliths continuously fumigated with NH₃ or sprayed with NH₄Cl were used to assess the potential for using ¹⁵N values in determining the area of influence around a point NH₃ emission source. ¹⁵N values are being increasingly used as environmental tracers and we tested the hypothesis that the ¹⁵N signal from an NH₃ emission source is observable in nearby vegetation. Using modified monitoring devices, atmospheric NH₃ concentrations were found to decrease with distance from source, with ¹⁵N values also reflecting this trend, producing a signal shift with changing concentration. Open top chamber studies of ¹⁵N values of Calluna vulgaris (L.) Hull indicated a correlation with deposition treatments in current year shoots. Analysis of Calluna shoots from the NH₃ release showed a similar trend of ¹⁵N enrichment. Significant linear correlations between ¹⁵N and percent N in plant material were found, both in the controlled conditions of the open top chambers and at the NH₃ release site, illustrating the possible use of this technique in N deposition biomonitoring.     

A carbon-13 method for evaluating degradation of starch-based polymers

A new method for evaluating biodegradability of starch-based and certain other polymer blends uses the pre- and postexposure stable carbon isotope composition of material coupled with weight loss data to determine which components have degraded. The naturally occurring stable isotope of carbon.¹³C, is enriched in corn starch (¹³C, approx. –11) compared to petroleum-derived synthetic polymers (¹³C, approx. –32). Results on starch-synthetic polymer blends indicate that the ¹³C signatures of these blends are near-linear mixtures of their component ¹³C. Values of a ¹³C for starch-synthetic polymer blends exposed to biologically active laboratory soil and artificial seawater conditions are depleted in¹³C compared to unexposed samples, suggesting loss of the starch component. Combined with weight loss data for the exposed samples, the ¹³C values are statistically consistent with models requiring loss of the soluble component glycerin, followed by loss of starch, then petrochemical polymer, or simultaneous loss of starch and petrochemical polymer. Replicate ¹³C analyses of starch-synthetic polymer blends increase the statistical power of this relatively inexpensive, accessible technique to discriminate between degrading components.     

Synthesis and environmental degradation of polyesters based on poly (ε-caprolactone)

Poly (-caprolactone) (PCL), poly (-valerolactone) (PVL), poly (-caprolactone-co--valerolactone) [P(CL-co-VL)], and poly (-caprolactone-co-ethylene oxide-co--caprolactone) (PCL-PEO-PCL) were synthesized by ring-opening and diol-initiated polymerization of -caprolactone and -valerolactone. The degradation of the samples by chemical hydrolysis and in a soil burial test was evaluated. It was found that PCL, PVL, and P(CL-co-VL) degrade mainly enzymatically. The rate of degradation depends on their molecular weight, chemical structure, composition, and morphology. PCL-PEO-PCL block copolymers exhibit a repelling effect to the microorganisms in the soil, which depends on the molecular weight and relative amount of PEO block in the copolymer.     

The Application of Stable Isotopes for Assessing the Hydrological, Sulfur, and Iron Balances of Acidic Mining Lake ML 111 (Lusatia, Germany) as a Basis for Biotechnological Remediation

Stable isotope (¹⁸O–H₂O, ²H–H₂O ³⁴S–SO₄ ^2-) andhydrochemical data (SO₄ ^2-, Fe-concentrations) have beenused to estimate the annual groundwater inflow and outflow of mining lake ML 111 and to calculate the total amount of dissolvedsulfate and iron that is carried into the lake by groundwater. The hydrological balance suggests an annual groundwater inflow of 23 700 m³ and an annual groundwater outflow of 15 700 m³. The calculation of the sulfur and iron balances yielded an annual sulfate input of 37 800 kg and an annual iron input of 7000 kg with the groundwater inflow. Furthermore it was shown that significant fluxes of these elements go into the lake sediments which results in continuous release of acidity in the lake water.     

Tree Leaf Biomarkers for Atmospheric Nitrogen Deposition

The aim of this paper was to investigate the effects of nitrogen (N) deposition on tree N cycling and identify potential biomarkers forNdeposition. Between April and October 2002 extensive fieldwork was undertaken at Mardley Heath in Hertfordshire. This woodland, located adjacent to the A1(M) motorway, is exposed to high levels of atmospheric nitrogen oxides from the traffic. Measurements of ¹⁵N, in vivo nitrate reductase (NR) activity, tissue, xylem and surface nitrate concentrations as well as N concentration and growth were made along a 700-m transect at 90° to the motorway. The ¹⁵N data show that oxidised N from the road traffic is taken up by nearby trees and is incorporated into plant tissues. Our measurements of NR activities suggest elevated rates close to the motorway. However, xylem sap, leaf tissue and leaf surface nitrate concentrations showed no differences between the roadside location and the most distant sampling point from the motorway. Taken together the ¹⁵N and nitrate reductase data suggest uptake and assimilation of N through the foliage.We conclude that for this lowland deciduouswoodland, tissue, xylem and surface measurements of nitrate are unreliable biomarkers for N deposition whereas ¹⁵N, growth measurements and integrated seasonal NR might be useful. The results also point to the benefit of roadside tree planting to screen pollution from motor vehicles.     

Ring-Opening Polymerization of Cyclic Esters onto Liquefied Biomass

Ring-opening polymerization of cyclic esters (-caprolactone, -valerolactone, and l-lactide) onto liquefied biomass (LB) was conducted to obtain the polyester-type polyol and to regulate the characteristics of LB. IR and ¹H-NMR spectra of the obtained polyol showed that the polymerization was successfully conducted in the presence of acid catalyst, which is used in liquefaction. The molecular weight (M_w), hydroxyl value, and viscosity were controllable by changing the reaction conditions. Polyester-type polyurethane foams with a wide range of properties were prepared from the obtained polyol with the appropriate combinations of foaming agents.     

Sulfur Metabolism in Polluted Sphagnum Peat Bogs: A Combined 34S–35S–210Pb Study

The size and isotopic behavior of sulfur pools in²¹⁰Pb-dated peat cores were investigated to obtain aninsight into retention mechanisms of pollutant S in twomountain-top peatlands of the Northern Czech Republic, CentralEurope. The bogs were situated 40 km apart in an area whichbetween the years 1985 and 1995 received as much as 130 kg Sha^-1 yr^-1 from the atmosphere. Vertical peataccretion was faster at Pod Jelení horou (JH) than atVelký moál (VM). Organic carbon-bonded S was themost abundant sulfur pool, constituting 77 and 65 wt. % at JHand VM, respectively. At JH both the S concentration maximumand the highest annual S deposition rate were displaceddownward by more than 20 years (from 1987 to the 1960s)indicating that the buried S is vertically mobile. At VM the Sconcentration was the highest in the topmost 2-cm section eventhough atmospheric S deposition peaked in 1987. Differentmechanisms of S isotope redistribution prevailed in thetopmost peat layers at JH, where a negative ³⁴Sshift occurred, and at VM, where a positive ³⁴Sshift occurred. Bacterial sulfate reduction was responsiblefor the negative ³⁴S shift at JH. One possibleexplanation of the positive ³⁴S shift at VM isrelease of ³²S-enriched products of mineralization duringpeat diagenesis. There was a strong positive correlationbetween the abundance of total and pyrite S along the profiles.The presence of pyrite S at VM (526 ± 60 ppm) suggestedthat even at VM bacterial sulfate reduction occurred. Ananaerobic incubation of JH peat indicated sulfate reductionrate of 600 nmol g^-1 day^-1. The turnover times forinorganic S pools were shorter than for the organic S pools.Cumulative S contents in the Czech peat bogs were found to besignificantly lower than in similar sites in the NortheasternU.S., even though the atmospheric S inputs were more thanthree times higher at the Czech sites. Possible causes of suchdiscrepancy are discussed.     

Novel Biobased Polyurethanes Synthesized from Soybean Phosphate Ester Polyols: Thermomechanical Properties Evaluations

Biobased polyurethanes from soybean oil–derived polyols and polymeric diphenylmethane diisocyanate (pMDI) are prepared and their thermomechanical properties are studied and evaluated. The cross-linked biobased polyurethanes being prepared from soy phosphate ester polyols with hydroxyl contents ranging from 122 to 145 mg KOH/g and pMDI within 5 min of reaction time at 150°C in absence of any catalyst show cross-linking densities ranging from 1.8 × 10³ to 3.0 × 10³ M/m³, whereas glass transition temperatures vary from approximately 69 to 82°C. The loss factor (tan ) curves show single peaks for all these biobased polyurethanes, thus indicating a single-phase system. The storage moduli (G) at 30°C range from 4 × 10⁸ to 1.3 × 10⁹ Pa. Upon postcure at 150°C, the thermomechanical properties can be optimized. Cross-link densities are improved significantly for hydroxyl content of 139 and 145 mg KOH/g at curing time of 24 h. Similarly, glass transition temperature (T_g) and storage moduli around and after T_g are increased. Meanwhile, tan intensities decrease as result of restricted chain mobility. Longer exposure time (24 h) induces thermal degradation, as evidenced by thermogravimetric analysis (TGA). The dynamic mechanical (DMA) analysis shows that postcure at 100°C for times exceeding 24 h also leads to improved properties. However, cross-linking densities are lower compared to postcure carried out at 150°C.     

The Role Played by Acetyl Group Distribution Patterns in Substituted Starch Toward Enzymatic De-acetylation and Chain Fragmentation

The nature and distribution of the acetylated groups were evaluated by ¹³C-NMR and ¹H-NMR. The starch substrate with a DS of 1.5 comprises only two patterns: -(14)-d-glucopyranose and 2,3,6-tri-O-acetyl--(14)-d-glucopyranose. The starch with a DS of 3.0 also comprises two patterns: 2,3,4,6-tetra-O-acetyl--(14)-d-glucopyranose and 2,3,6-tri-O-acetyl--(14)-d-glucopyranose; whereas starch (DS = 1.9) contains 4 patterns: 2,3,6-tri-O-acetyl--(14)-d-glucopyranose, 2,3,4,6-tetra-O-acetyl--(14)-d-glucopyranose terminal, 2,6-di-O-acetyl--(14)-d-glucopyranose, and 3,6-di-O-acetyl--(14)-d-glucopyranose. Using esterase from Viscozyme, it has been possible to hydrolyze up to 7% of the DS 3.0 starch. An -amylase (Fungamyl 800) was then added to these acetylesterases. With a 2.4 FAU/mL fraction of -amylase and 2.4 U/mL from the Viscozyme's acetylesterase, 28% of the acetylated end groups were hydrolyzed for the starch substrates with DS 3.0. Moreover, a synergic action between -amylase and acetylesterase was noticed, allowing fragmentation of 32% for DS 1.5, 30% for DS 1.9, and 11% for DS 3.0.     

Catalytic decomposition of hydrocarbon into hydrogen and carbon in a spouted-bed reactor as the second-stage reactor of a plastic recycling process

A two-stage process for the chemical recycling of plastics is proposed. In this process, which consists of two reactors, plastics are converted into hydrogen and carbon. In the first reactor, plastic chips are thermally decomposed into hydrocarbons. In the second reactor, the hydrocarbons formed in the first reactor are catalytically decomposed into carbon and hydrogen. In this study, in order to obtain basic data for the second reactor, propene was catalytically decomposed in a laboratory-scale spouted-bed reactor (600mm high, 21.6mm internal diameter, made of SUS304). The effect of the type of spouting medium used on the decomposition behavior of propene was investigated using four types of spouting medium (nickel-plated -alumina, palladium-plated -alumina, nickel-impregnated -alumina, and -alumina). The nickel-impregnated -alumina gave the best propene conversion and hydrogen yield.     

Investigation of the Aerobic Biodegradability of Several Types of Cyclodextrins in a Laboratory-Controlled Composting Test

The biodegradation of several types of cyclodextrins (CDs) under laboratory-controlled composting conditions was investigated. CDs are used in a broad range of applications in food, pharmaceutical, medical, chemical, and textile industries because of their specific chemical characteristics related to their hydrophobic interior and hydrophilic exterior. The three naturally occurring cyclodextrins -CD, -CD, and -CD proved to be completely and readily biodegradable. Chemical modification of these basic compounds can have a major impact on the biodegradation rate and final biodegradation percentage. Fully acetylated -CD and -CD were found to be nonbiodegradable during 45 days of composting. Reducing the degree of acetylation had a positive effect on the biodegradation. Complete biodegradation was obtained for partially acetylated -CD with a degree of substitution (DS) of 7. The methylation (DS = 13) of -CD resulted in an undegradable compound during the 47 days composting, while (2-hydroxy)propyl--CD reached a plateau in biodegradation at a percentage of 20%. The incorporation of the antimicrobial agents imazalil and allyl-isothiocyanate into -CD had no negative impact on biodegradation, which makes these antimicrobial agents/CD complexes suitable for incorporation into biodegradable active packaging.     

Gas and Aerosol Loadings at Holme Moss 1996–1998 Measurements and Analysis Using Back-Trajectory Clustering

A continuous two-year atmospheric datasetcomprising gas and aerosol loadings from amountain site in northern England (Holme Moss,W1°5130 N53°320) is presented. The data are analysed with respect to three-dayback-trajectories that are grouped according to aclustering technique that allows speed, directionand curvature of the airmass track to beconsidered. The technique is successful inseparating the data into chemically distinctsubsets. Up to 29% of the variance in the datais explained by back-trajectory clusters. Slow trajectories are associated with highloadings especially for the oxides of nitrogen,which may imply a local source for much of thesuspended pollutant. The data suggest thatproduction of nitrate and sulphate is limited byoxidant availability at least in the winter. Itmay be possible to optimise the analytical powerof the technique by increasing the importance ofrecent airmass track in determining clusterallocation. This applies especially to the totalsulphur loading.     

Solid State Reactions of Potato Starch with Urea and Biuret

Reaction of granular potato starch with urea and biuret resulted in the formation of products, which were soluble neither in cold nor boiling water. The net reaction was a monosubstitution of the hydrogen atom in one hydroxyl group in each D-glucose unit of starch with the either CO–NH₂ or CO–NH–CO–NH₂ moiety, respectively. Properties of the products, particularly these with urea, depended on the mode of reaction. Reactions were carried out in the microwave oven as well as with convection heating. The products retained the granular form of starch but a vast majority of granules were damaged. -Amylolysis of those materials revealed that their susceptibility to the enzyme increasing in the order: starch-amylolysis with simultaneous insolubility in water make these products suitable as ruminant fodder and, eventually, biodegradable material.     

Remediation of Persistent Organic Pollutants Using a Novel Two-Phase Soil Washing Biosorption Process

A two-phase soil washing biosorption process was developed for the remediation of p,p-DDT-contaminated soil. The process involved desorption of contaminants from soil using dilute primary alcohols (40% 1-propanol) followed by contaminant removal from cosolvent solutions using fungal biosorption. Bench scale remediation studies were preformed to simulate ex situ (recycling experiment) or in situ (soil column study) treatment strategies. Both systems were effective at cleaning the soil to below Australian regulatory p,p-DDT levels. After 50–80 hours of soil washing, over 93% of p,p-DDT was removed from the soil(990 mg kg^-1 to <65 mg kg^-1) using either of these methods.p,p-DDT was removed from the cosolvent phase by sorption onto the fungal biomass. This resulted in only low levels of p,p-DDT remaining in the cosolvent solution(<1.5 mg l^-1). The application of both treatment strategies resulted in the rapid clean up of p,p-DDT-contaminated soil and the potential to recycle cosolvent solutions. The ability to recycle cosolvent solutions provides a mechanism for cost reductions of the remediation strategy.     

Hysteresis in Reversal of Central European Mountain Lakes from Atmospheric Acidification

Extremely high emissions of S and N compounds in Central Europe (both 280 mmol m^-2 yr^-1) declined by 70and 35%, respectively, during the last decade. Decreaseddeposition rates of SO₄ ^-2, NO₃ ^-, and NH₄ ⁺ in the region paralleled emission declines. The reduction in atmospheric inputs of S and N to mountain ecosystemshas resulted in a pronounced reversal of acidification in the Tatra Mountains and Bohemian Forest lakes. Between the 1987–1990and 1997–1999 periods, concentrations of SO₄ ^-2 and NO₃ ^- decreased (average ± standard deviation) by 22±7 and 12±7 mol L^-1, respectively, in theTatra Mountains, and by 19±7 and 15±10 mol L^-1, respectively, in the Bohemian Forest. Their decrease was compensated in part (1) by a decrease in Ca²⁺ + Mg²⁺ (17±7 mol L^-1) and H⁺ (4±6 mol L^-1), and an increase in HCO₃ ^-(10±10 mol L^-1) in the Tatra Mountains lakes, and (2) by a decrease in Al (7±4 mol L^-1), Ca²⁺ + Mg²⁺ (9±6 mol L^-1), and H⁺ (6±5 mol L^-1), in Bohemian Forest lakes. Despite the rapid decline in lake water concentrations of SO₄ ^-2 and NO₃ ^- in response to reduced S and N emissions, their present concentrations in some lakes are higher than predictionsbased on observed concentrations at comparable emission rates during development of acidification. This hysteresis in chemical reversal from acidification has delayed biological recovery of the lakes. The only unequivocal sign of biological recovery hasbeen observed in erné Lake (Bohemian Forest) where a cladoceran species Ceriodaphnia quadrangular has recentlyreached its pre-acidification abundance.     

The Effect of Nitrogen Enrichment on the Carbon Sink in Coniferous Forests: Uncertainty and Sensitivity Analyses of Three Ecosystem Models

Estimates of the global carbon sink induced by nitrogen enrichment range vary widely, from nearly zero to 2.3 Gt C year^-1. It is necessary to reduce this uncertainty if we are to make accurate predictions of the future magnitude of the terrestrial carbon sink. Here, we present a Monte Carlo approach to uncertainty and sensitivity analysis of three ecosystem models, Century,BGCand Hybrid. These models were applied to a coniferous forest ecosystem in Sweden. The best estimate of the change in total carbon content of the ecosystem with the cumulative change in nitrogen deposition over 100 years, C_total/N_deposition was 20.1 kg C (kg N)^-1 using the pooled mean, with a pooled standard deviation of 13.8 kg C (kg N)^-1. Variability in parameters accounted for 92% of the total uncertainty in C_total/N_deposition, and only 8% was attributable to differences between models. The most sensitive parameters were those which controlled the allocation of assimilate between leaves, roots and stem. In particular, an increase in allocation to fine roots led to a large reduction in C_total/N_deposition in all models, because the fine roots have a very high turnover rate, and extra carbon allocated there is soon lost through mortality and decomposition.     

Preparation conditions and swelling equilibria of biodegradable hydrogels prepared from microbial poly(γ-glutamic acid) and poly(ε-lysine)

Biodegradable hydrogels prepared by -irradiation from microbial poly(amino acid)s are reviewed. pH-sensitive hydrogels were prepared by means of -irradiation of poly(-glutamic acid) (PGA) produced byBacillus subtilis IFO3335 and poly(-lysine) (PL) produced byStreptomyces albulus in aqueous solutions. The preparation conditions, swelling equilibria, hydrolytic degradation, and enzymatic degradation of these hydrogels were studied. A hydrogel with a wide variety of swelling behaviors has been produced by -irradiation from a mixture solution of PGA and PL.Paper presented at the 4th International Workshop on Biodegradable Plastics and Polymers, October 11–14, 1995, Durham, New Hampshire, USA.     

Assessment of Bacterial Degradation of Aromatic Hydrocarbons in the Environment by Analysis of Stable Carbon Isotope Fractionation

¹³C/¹²C stable carbon isotope fractionation was used to assess biodegradation in contaminated aquifers with toluene as a model compound. Different strains of anaerobic bacteria (Thauera aromatica, Geobacter metallireducens, and the sulfate-reducing strain TRM1) showed consistent ¹³C/¹²C carbon isotope fractionation with fractionation factors between C = 1.0017 and 1.0018. In contrast, three cultures of aerobic organisms, using different mono- and dioxygenase enzyme systems to initiate toluene degradation, showed variable isotope fractionation factors of C = 1.0027 (Pseudomonasputida strain mt-2), C = 1.0011 (Ralstonia picketii), andC = 1.0004 (Pseudomonas putida strain F1). The great variability of isotope fractionation between different aerobic bacterial strains suggests that interpretation of isotope data in oxic habitats can only be qualitative. A soil column was run as a model system for contaminated aquifers with toluene as the carbon source and sulfate as the electron acceptor and samples were taken at different ports along the column. Microbial toluene degradation was calculated based on the ¹³C/¹²C isotope fractionation factors of the batch culture experiments together with the observed ¹³C/¹²C isotope shifts of the residual toluene fractions. The calculated percentage of biodegradation, B, correlated well with the decreasing toluene concentrations at the sampling ports and indicated the increasing extent of biodegradation along the column. The theoretical toluene concentrations as calculated based on the isotope values matched the measured concentrations at the different sampling ports indicating that the Rayleigh equation can be used to calculate biodegradation in quasi closed systems based on measured isotope shifts. A similar attempt was performed to assess toluene degradation in a contaminated, anoxic aquifer. A transect of groundwater wells was monitored along the main direction of the groundwater flow and revealed decreasing concentrations accompanied with an increase in the ¹³C/¹²C stable carbon isotope ratio of the residual toluene. Calculation of the extent of biodegradation based on the isotope values and laboratory derived isotope fractionation factors showed that the residual toluene was degraded to more than 99% by microbial activity. Calculation of the theoretical residual toluene concentrations based on the measured isotope values described the strongly decreasing concentrations along the plume. Other aromatic hydrocarbons like benzene and naphthalene which were analysed in the same course also showed decreasing concentrations along the groundwater flow path accompanied by increasing ¹³C values indicating biodegradation.     

What substances or objects should be recycled? The recycling legislative experience in Taiwan

The legislative framework of waste management in Taiwan has never been efficient, mainly due to unclear definitions and regulations. In 2002, this system was split into two parts by enacting a new law, the Resource Recycling and Re-use Act (RRRA). However, it then became more complicated and recycling effectiveness was impeded. The causes were mainly the unclear definitions, conflicts about the scope, and issues between the RRRA and the Waste Disposal Act (WDA). This article examines the recycling legislation experience in Taiwan, and proposes two modifications for resolving these problems. The first proposal is merging these two acts into one. The second proposed modification maintains a two-system structure but introduces a new subject, discards, into the law. The subject of discards is further categorized as recyclable resources or waste, which correspond to recycling operations and disposal operations, respectively. The new structures, interfaces, prerequisites, properties, and comparisons are also explained.     

Decomposition reactions of epoxy resin and polyetheretherketone resin in sub- and supercritical water

Epoxy resin and polyetheretherketone (PEEK) resin were decomposed into their monomers such as phenol, cresols, and their analogues by thermal treatment in sub- and supercritical water in a 10-ml tubing bomb reactor. The addition of basic compounds such as Na₂CO₃ was effective in promoting the decomposition reaction of the resins. In the reaction of epoxy resin, the yield of identified products reached 10% for the reaction at 703K over 1h. In the reaction of PEEK resin, the total yield of phenol and dibenzofuran reached 88% for the reaction at 703K over 3h. Chemical participation of water in the decomposition reaction was confirmed by the reaction of dinaphthylether.