Recycling, landfill consumption, and CO2 emission: analysis by waste input–output model

The emission of waste in an economy, including landfill, is to a large extent determined by its patterns of technology, institutions, and lifestyle. A mathematical model (the waste input–output model) is presented that gives a simple analytical representation of this interdependence. The model was used to evaluate the effects of alternative waste disposal and recycling options on the levels of industrial production, landfill consumption, and the emission of carbon dioxide, and also to analyze the overall dependence on landfill of individual industries. It was found that a systematic combination of the options could be effective in reducing the overall landfill consumption and carbon dioxide emission. Received: November 4, 2000 / Accepted: August 2, 2001     

Application of the rescue number to the evaluation of remediation technologies for contaminated ground

An improved rescue number, RN_SOIL, which is an indicator for evaluating remediation technologies for contaminated ground that is based on both the risk and the remediation cost, is proposed as a tool of risk communication. The risk posed by contaminated ground is indicated by the figure of treatment priority at time t, FTP(t), which represents the human health risk as the number of people affected by the contaminated ground at time t during the remediation process. The calculation of the value of FTP(t) is based on exposure to contaminants that have migrated through environmental media from the contaminated ground, and is estimated by using a CalTOX model and the Monte Carlo method. The integration of FTP(t) with time, which represents the cumulative number of people affected by the contaminated ground, is used to estimate the performance of individual remediation technologies in risk reduction. The figure of unprocessibility for waste (FUW), which represents difficulties in remediation, is expressed as the remediation cost. FUW is estimated by using actual costs per unit volume of remediated soil. As an overall performance value, the rescue number for each remediation technology for contaminated ground (RN_SOIL) is calculated by multiplication of the integral FTP(t) by FUW. Smaller values of RN_SOIL are judged to indicate a better technology. The rescue index (RI), calculated as the ratio of the reduction of the integral FTP(t) to FUW, indicates the cost-effectiveness of the remediation technologies. Successful estimation of the indices (FTP(t), integral FTP(t), FUW, RN_SOIL and RI) demonstrate the usefulness of these indices in risk communication.Part of this paper was presented at 13th meeting of Japan Society of Waste Management Experts (2002)     

Area-specific temporal changes of species composition and species-specific range shifts in rocky-shore mollusks associated with warming Kuroshio Current

Increases of low-latitude species in various sea areas and poleward shifts of ranges of many species have been reported and linked to warming environments. To examine the generality of these trends for mollusks, we conducted 7 quadrat surveys during 1978–2006 on Pacific rocky shores in Japan (26.6–45.0°N). Results showed that the dominance of southern species increased on 11 of the 15 shores in a southern, warming sea area but on only 1 of the 6 shores in a northern area with no warming trend. The latitudes of species ranges increased on average but showed large interspecific variations which showed a weak, positive correlation with interspecific taxonomic distance. The differences of these results from the previously reported trends are discussed in relation to the unique current patterns in our study area and the phylogenetic constraints of species-specific responses to a warming environment.     

Quantitative determination of Escherichia coli based on the electrochemical measurement of bacterial catalase activity using H2O2-selective organic/inorganic-hybrid sol-gel film-modified Pt electrode

Quantitative determination of Escherichia coli (E. coli) concentration was achieved by measuring the intrinsic catalase activity of E. coli using novel H₂O₂-selective organic/inorganic-hybrid sol-gel film-modified platinum (Pt) wire electrode. This hybrid sol-gel film is composed of three kinds of organosilanes and two biopolymers (i.e., chitosan and bovine serum albumin), and exhibited an excellent permselectivity toward H₂O₂ based on a size-exclusive mechanism. The steady-state anodic current for 100 [xmol/L H₂O₂ at +0.6 V (vs. Ag/AgCl) in 0.1 mol/L phosphate buffer (pH 6.5) solution was apparently diminished by the addition of E. coli samples, due to the decomposition of H₂O₂ by intrinsic catalase activity of E. coli. The time-dependent decrease in current (–AI/At) was significantly dependent on the E. coli concentration. The –AI/At was enhanced by the permeabilization pretreatment of E. coli samples with the mixed solution of polymyxin B and lysozyme. This H₂O₂-selective organic/inorganic-hybrid sol-gel film-modified platinum (Pt) wire electrode allowed quantitative determination of E. coli concentration ranging from 10⁶ to 10⁹ CFU/mL within 30 min. This method required no label and complicated procedure, and allowed rapid, simple and cost-effective quantitative electrochemical determination of catalase-positive bacteria.     

Highly sensitive flow-biosensor for toxic phenolic compounds using tyrosinase and acridine orange-adsorbed carbon felt

Tyrosinase (TYR, EC 1.14.18.1) was physically adsorbed onto a carbon felt (CF) together with acridine orange (AO). Coadsorption of AO was essential to prevent the denaturation of the TYR at the CF surface. The resulting TYR and AO-coadsorbed CF (TYR/AO-CF) was successfully utilized as a detection unit of novel and highly sensitive amperometric flow-biosensor for toxic chlorophenol compounds. Standard solutions of phenolic compounds (200 μL) were injected, and the cathodic peak currents due to the reduction current of o-quinones produced by the TYR-catalyzed oxidation (phenolase activity) were detected at the applied potential of ?50 mV vs. Ag/AgCl. In this reaction, the electrochemically generated catechol compounds from o-quinones are re-oxidized repeatedly by catecholase activity of the TYR, leading to a sufficient amplified signal. The TYR/AO-CF exhibited much higher selectivity toward p-chlorophenol as compared with other chlorophenol compounds. When 0.1 mol/L phosphate buffer (pH 7.0) was used as a carrier at flow rate of 3.0 mL/min, cathodic peaks for p-chlorophenol was linear in the concentration range between 0.1 and 10 [xmol/L (sensitivity: 1.41(mA-L)/mmol) with sampling rate (30 samples/h), and the detection limit ofp-chlorophenol was found to be 2.13 ? 10⁸ mol/L (S/N = 3. The ratio of signal and noise is 3). The TYR/AO-CF kept more than 80% of original activity after the storage in 0.1 mol/L phosphate buffer (pH 7.0) containing 0.2 mmol/L AO at 4°C.     

Electropolymerized poly（Toluidine Blue）-modified carbon felt for highly sensitive amperometric determination of NADH in flow injection analysis

Poly(pheniothiazine) films were prepared on a porous carbon felt (CF) electrode surface by an electrooxidative polymerization of three phenothiazine derivatives (i.e.,Tthionine (TN), Toluidine Blue (TB) and Methylene Blue (MB)) from 0.1 mol/L phosphate buffer solution (pH 7.0). Among the three phenothiazies, the poly(TB) film-modified CF exhibited an excellent electrocatalytic activity for the oxidation of nicotinamide adenine dinucleotide reduced form (NADH) at +0.2 V vs. Ag/AgCl. The poly(TB) film-modified CF was successfully used as working electrode unit of highly sensitive amperometric flow-through detector for NADH. The peak currents (peak heights) were almost unchanged, irrespective of a carrier flow rate ranging from 2.0 to 4.1 mL/min, resulting in the measurement of NADH (ca. 30 samples/hr) at 4.1 mL/min. The peak current responses of NADH showed linear relationship over the concentration range from 1 to 30 mol/L (sensitivity: 0.318 A/( mol/L); correlation coefficient: 0.997). The lower detection limit was found to be 0.3 mol/L (S/N = 3).     

Direct electrochemistry of glucose oxidase and biosensing for glucose based on DNA/chitosan film

Glucose oxidase (GOD) is widely used in the glucose biosensor industry. The amperometric biosensors based on directly electron transfer (DET) between an electrode and immobilized GOD are especially promising. In this article, GOD was immobilized with a DNA/chitosan bio-material film on GC electrode, and the DET of GOD on DNA/chitosan was studied. The cyclic voltammetric results indicated that the GOD immobilized in the DNA/chitosan film underwent DET reaction, and the cyclic voltammogram displayed a pair of well-defined redox peaks with a formal potential of ?0.45 V (vs. Ag/AgCl) at pH 5.5. The response showed a surface-controlled electrode process with an electron transfer rate constant of 0.91 sec^?1 determined in the scan rate range from 10 to 100 mV/sec. The GOD immobilized in DNA/chitosan membrane retained its biocatalytic activity and stability. The immobilized GOD could electrocatalyze the reduction of dissolved oxygen and resulted in a great increase of the reduction peak current. Upon the addition of glucose, the reduction peak current decreased, which could be used for glucose detection with a sensitivity of 0.48 μA/(mmol/L), a linear range from 0.04 to 2.28 mmol/L and a detection limit of 0.04 mmol/L at a signal-to-noise ratio of 3. The sensor could exclude the interference of commonly coexisted uricacid and ascorbic acid.     

Control of metal toxicity, effluent COD and regeneration of gel beads by immobilized sulfate-reducing bacteria

Over the last few decades, the use of sulfate-reducing bacteria (SRB) in the treatment of heavy-metal containing wastewaters including acid mine drainage has become a topic of scientific and commercial interest. However, technical difficulties such as the sensitivity of SRB to toxic metals and high effluent COD limit the widespread use of SRB in high heavy-metal containing wastewater. The aim of this study was to clarify the reasons why the immobilized SRB sludge with inner cohesive carbon source (ISIS) process can endure high metal toxicity and decrease effluent COD. The ISIS process can physically set apart SRB and free the system of external influences such as the surrounding toxic metallic ions, as well as form inner carbon sources to avoid high effluent COD. Metal toxicity and bead durability are the two major factors which influence the regeneration and reuse of gel beads. Reuse of suspended SRB sludge and beads crosslinked with boric acid were unsuccessful due to metal toxicity and agglomeration of beads, respectively. However, beads crosslinked with ammonium sulfate prevented agglomeration of beads allowing successful bead regeneration and reuse. The result of four cyclic trials showed that over 99% of zinc was removed in each trial using these beads.     

Assays of dioxins and dioxin-like compounds in actually contaminated soils using transgenic tobacco plants carrying a recombinant mouse aryl hydrocarbon receptor-mediated β-glucuronidase reporter gene expression system

The transgenic tobacco plant XD4V-26 carrying the recombinant mouse aryl hydrocarbon receptor XD4V-mediated β-glucuronidase (GUS) reporter gene expression system was used for assay of dioxins and dioxin-like compounds consisting of polychlorinated dibenzeno-p-dioxins, polychlorinated dibenzofurans, and coplanar polychlorinated biphenyls (Co-PCBs) in actually contaminated soils. The transgenic tobacco plant XD4V-26 showed a significant dose-dependent induced GUS activity when cultured on MS medium containing PCB126 [toxic equivalency factor (TEF) = 0.1]. In contrast, PCB169 and PCB180, which have 0.03 of TEF and unassigned TEF values, respectively, did not significantly induce GUS activity under the same conditions as with PCB126. When the tobacco plants were cultivated for up to 5 weeks on actually contaminated soils with dioxins and dioxin-like compounds collected from the periphery of an incinerator used for disposal of residential and industrial wastes, GUS activity in the leaves was dose-dependently increased. The plants clearly detected 360 pg-TEQ g^?1 of dioxins and dioxin-like compounds in this assay. There was a positive correlation between GUS activity and TEQ value of dioxins and dioxin-like compounds in the plants. This assay does not require any extraction and purification processes for the actually contaminated soil samples.     

Fluxes of carbon dioxide, methane and nitrous oxide in two contrastive fringing zones of coastal lagoon, Lake Nakaumi, Japan

We measured fluxes of carbon dioxide (CO(2)), methane (CH(4)), and nitrous oxide (N(2)O) simultaneously in two typical fringing zones, sandy shore and salt marsh, of coastal lagoon, Lake Nakaumi, Japan, in mid-summer 2003. Our aim was to quantify net the greenhouse gases (GHGs) fluxes and examine key factors, which control variation of the GHGs fluxes in the two sites. Net CO(2) and CH(4) fluxes were markedly different between the two sites; magnitudes and variations of the both fluxes in sandy shore were lower than those of salt marsh. Meanwhile, magnitude and variation of net N(2)O flux in the two sites were similar. In sandy shore, temporal and spatial variation of the three GHGs fluxes were highly controlled by water level fluctuation derived from astronomic tide. In salt marsh, spatial variation of the three GHGs fluxes were correlated with aboveground biomass, and temporal variation of CO(2) and CH(4) fluxes were correlated with soil temperature. The sum of global warming potential, which was roughly estimated using the observed GHGs fluxes, was ca. 174-fold higher in salt marsh than in sandy shore.