Application of real option analysis for planning under climate change uncertainty: a case study for evaluation of flood mitigation plans in Korea

With concerns regarding global climate change increasing, recent studies on adapting to nonstationary climate change recommended a different planning strategy that could spread risks. Uncertainty in global climate change should be considered in any decision-making processes for flood mitigation strategies, especially in areas within a monsoon climate regime. This study applied a novel planning method called real option analysis (ROA) to an important water resources planning practice in Korea. The proposed method can easily be applied to other watersheds that are threatened by flood risk under climate change. ROA offers flexibility for decision-makers to reflect uncertainty at every stage during the project planning period. We successfully implemented ROA using a binomial tree model, including two real options—delay and abandon—to evaluate flood mitigation alternatives for the Yeongsan River Basin in Korea. The priority ranking of the four alternatives between the traditional discount cash flow (DCF) and ROA remained the same; however, two alternatives that were assessed as economically infeasible using DCF, were economically feasible using ROA. The binomial decision trees generated in this study are expected to be informative for decision-makers to conceptualize their adaptive planning procedure.     

A case study of development and application of a streamlined control and response modeling system for PM2.5 attainment assessment in China

This article describes the development and application of a streamlined air control and response modeling system with a novel response surface modeling-linear coupled fitting method and a new module to provide streamlined model data for PM_(2.5) attainment assessment in China.This method is capable of significantly reducing the dimensions required to establish a response surface model,as well as capturing more realistic response of PM_(2.5) to emission changes with a limited number of model simulations.The newly developed module establishes a data link between the system and the Software for Model Attainment Test—Community Edition(SMAT-CE),and has the ability to rapidly provide model responses to emission control scenarios for SMAT-CE using a simple interface.The performance of this streamlined system is demonstrated through a case study of the Yangtze River Delta(YRD) in China.Our results show that this system is capable of reproducing the Community Multi-Scale Air Quality(CMAQ) model simulation results with maximum mean normalized error 3.5%.It is also demonstrated that primary emissions make a major contribution to ambient levels of PM_(2.5) in January and August(e.g.,more than50%contributed by primary emissions in Shanghai),and Shanghai needs to have regional emission control both locally and in its neighboring provinces to meet China's annual PM_(2.5)National Ambient Air Quality Standard.The streamlined system provides a real-time control/response assessment to identify the contributions of major emission sources to ambient PM_(2.5)(and potentially O_3 as well) and streamline air quality data for SMAT-CE to perform attainment assessments.     

Experimental and numerical calculations of waste R-134a thermal decomposition for energy and fluorine material recovery

Considering the global warming potential of R-134a (C₂H₂F₄) with the substantial generation of this refrigerant as waste material in various industrial sectors, the development of proper thermal destruction method of R-134a is of great practical significance. For this, experiment and numerical calculations have initially made for a tubular-type furnace in order to figure out the basic combustion characteristics of R-134a. A series of experimental investigations for the thermal decomposition of R-134a have been made as a function of wall temperature of tubular furnace and important reacting species such as O₂ and H₂O necessary for the decomposition of C₂H₂F₄ into HF, CO₂ and H₂O. In general, the thermal decomposition of R-134a is successfully made for the condition of temperature above 800 °C with the supply of stoichiometric amount of O₂ and these results are well agreed with numerical prediction. And this information is employed for the simulation of a full-scale, practical incinerator used for the CDM project. For this, numerical investigation has been made for a commercial-scale incinerator using CH₄–air flames for the proper destruction C₂H₂F₄ together with the control of pollutants such as CO and NO. In general, the destruction rate of C₂H₂F₄ appears more than 99.99 % and the generation of CO and NO species appears rather sensitive to the operational condition such as amount of water vapor. The numerical method of HFCs (hydrofluorocarbons) thermal treatment shows high possibility as a viable tool for the proper design and optimal determination of the operational condition for a HFCs incinerator.     

Understanding of regional air pollution over China using CMAQ,part I performance evaluation and seasonal variation

The U.S. EPA Models-3 Community Multiscale Air Quality (CMAQ) modeling system with the process analysis tool is applied to China to study the seasonal variations and formation mechanisms of major air pollutants. Simulations show distinct seasonal variations, with higher surface concentrations of sulfur dioxide (SO₂), nitrogen dioxide (NO₂), and particulate matter with aerodynamic diameter less than or equal to 10 μm (PM₁₀), column mass of carbon monoxide (CO) and NO₂, and aerosol optical depth (AOD) in winter and fall than other seasons, and higher 1-h O₃ and troposphere ozone residual (TOR) in spring and summer than other seasons. Higher concentrations of most species occur over the eastern China, where the air pollutant emissions are the highest in China. Compared with surface observations, the simulated SO₂, NO₂, and PM₁₀ concentrations are underpredicted throughout the year with NMBs of up to ?51.8%, ?32.0%, and ?54.2%, respectively. Such large discrepancies can be attributed to the uncertainties in emissions, simulated meteorology, and deviation of observations based on air pollution index. Max. 1-h O₃ concentrations in Jan. and Jul. at 36-km are overpredicted with NMBs of 12.0% and 19.3% and agree well in Apr. and Oct. Simulated column variables can capture the high concentrations over the eastern China and low values in the central and western China. Underpredictions occur over the northeastern China for column CO in Apr., TOR in Jul., and AODs in both Apr. and Jul.; and overpredictions occur over the eastern China for column CO in Oct., NO₂ in Jan. and Oct., and AODs in Jan. and Oct. The simulations at 12-km show a finer structure in simulated concentrations than that at 36-km over higher polluted areas, but do not always give better performance than 36-km. Surface concentrations are more sensitive to grid resolution than column variables except for column NO₂, with higher sensitivity over mountain and coastal areas than other regions.     

Prediction of Cd toxicity to Daphnia magna in the mixture of multi-walled carbon nanotubes and kaolinite

In this study, we investigated cadmium toxicity created by adsorption kinetics in several mixtures containing two types of multi-walled carbon nanotubes (COOH-MWCNT and NH₂-MWCNT) and natural kaolinite. Characteristics of two types of MWCNTs were measured by zeta potential and ATR FT-IR graphs and TEM images. The solution of CNTs and kaolinite was tested to study Cd adsorption kinetics and mechanisms of differentiation-associated toxicity using Daphnia magna in a binary system (Cd–MWCNTs and Cd–kaolinite) and a ternary system (Cd–MWCNTs–kaolinite). In the binary system, Cd removal efficiency was nearly 100% and 40% for MWCNTs and kaolinite because of surface charge, respectively, with increasing sorbent concentration. In the ternary system, the trend of adsorption rate was similar to that of binary system. In comparison with percent mortality in the binary system, the solution in the ternary system showed higher toxicity due to the interaction of MWCNTs–kaolinite coagulated particles, thereby decreasing Cd adsorption onto CNTs and kaolinites. Overall, kaolinite can affect the adsorption process of Cd on MWCNTs in negative ways, depending on adsorption state. In conclusion, our studies suggest that kaolinite differs with adsorption ability of Cd by MWCNTs, and toxicity is likely to be produced by multivariable regression in the adsorption state.

     

Characterization of pollutants in Florida street sweepings for management and reuse

Disposal and beneficial-use options for street sweeping residuals collected as part of routine roadway maintenance activities in Florida, USA, were assessed by characterizing approximately 200 samples collected from 20 municipalities. Total concentrations (mg/kg or μg/kg) and leachable concentrations (mg/L or μg/L) of 11 metals and a number of organic pollutant groups (volatile organics, semi-volatile organics, pesticides, herbicides, carbamates) in the samples were measured. The synthetic precipitation leaching procedure (SPLP) was performed to evaluate the leachability of the pollutants. From the total metal analysis, several metals (e.g., arsenic, barium, chromium, copper, nickel, lead, and zinc) were commonly found above their detection limits. Zinc was found to have the highest mean concentration of all metals measured (46.7 mg/kg), followed by copper (10.7 mg/kg) and barium (10.5 mg/kg). The metal with the smallest mean concentration was arsenic (0.48 mg/kg). A small fraction of the total arsenic, barium, lead, and zinc leached in some samples using the SPLP; leached concentrations were relatively low. A few organic compounds (e.g., 4,4′-DDT, endrin, and endosulfan II) were detected in a limited number of samples. When the total and leaching results were compared to risk-based Florida soil cleanup target levels and groundwater cleanup target levels, the street sweepings were not found to pose a significant human-health risk via direct exposure or groundwater contamination.     

Source attribution for mercury deposition in the contiguous United States: regional difference and seasonal variation

Quantifying the contribution of emission sources responsible for mercury deposition in specific receptor regions helps develop emission control strategies that alleviate the impact on ecosystem and human health. In light of the maximum available control technology (MACT) rules proposed by U.S. Environmental Protection Agency (EPA) and the ongoing intergovernmental negotiation coordinated by United Nations Environmental Programme (UNEP) for mercury, the Community Multiscale Air Quality Modeling System (CMAQ-Hg) was applied to estimate the source contribution in six subregions of the contiguous United States (CONUS). The considered source categories include electric generating units (EGU), iron and steel industry (IRST), other industrial point sources excluding EGU and IRST (OIPM), the remaining anthropogenic sources (RA), natural processes (NAT), and out-of-boundary transport (BC). It is found that, on an annual basis, dry deposition accounts for two-thirds of total annual deposition in CONUS (474 Mg yr(-1)), mainly contributed by reactive gaseous mercury (about 60% of total deposition). The contribution from large point sources can be as high as 75% near the emission sources (< 100 km), indicating that emission reduction may result in direct deposition decrease near the source locations. Out-of-boundary transport contributes from 68% (Northeast) to 91% (West Central) of total deposition. Excluding the contribution from out-of boundary transport, EGU contributes to about 50% of deposition in the Northeast, Southeast, and East Central regions, whereas emissions from natural processes are more important in the Pacific and West Central regions (contributing up to 40% of deposition). This suggests that the implementation of the new EPA MACT standards will significantly benefit only these three regions. Emission speciation is a key factor for local deposition. The source contribution exhibits strong seasonal variation. Deposition is greater in warm seasons due to stronger Hg0 oxidation. However, the contribution from anthropogenic sources is smaller in warm seasons because of larger emissions from natural processes and stronger vertical mixing that facilitates transport.     

Provenances of atmospheric dust over Korea from Sr–Nd isotopes and rare earth elements in early 2006

Sr and Nd isotopic composition of pre- and syn-Asian dust (Hwangsa) particles collected from three different water depths at two different offshore sites, western Korea and rare earth elemental composition of syn-Asian dust particles collected from three islands around the Korean Peninsula in late April 2006 were analyzed to interpret their provenance. The dust Sr–Nd isotopic compositions vary spatiotemporally, but they show specific values when the Hwangsa event occurred. Satellite images, airmass backward trajectory modeling, and comparison with Sr–Nd isotopic ratios and rare earth elements compositions of soils and desert sands of northern China all suggest the major source of dust particles for the late April 2006 Hwangsa event to be the Mu Us Desert in northern China. Dust particles of the pre-Hwangsa period include both background dusts and the previous Hwangsa event dust particles, and they are interpreted to have been originated from various arid regions of China such as the Hobq Desert, the Mu Us Desert, and the Taklamakan Desert in different times. Different background dust sources during pre-Hwangsa period in early 2006 resulted from the changing route of the westerlies.     

Evaluation of environmental impacts of food waste management by material flow analysis (MFA) and life cycle assessment (LCA)

This paper focuses on the evaluation of potential environmental impacts of food waste management practices by material flow analysis (MFA) and life cycle assessment (LCA) during different life cycle stages toward the environmentally sustainable options for Daejeon Metropolitan City (DMC) in Korea. The MFA and LCA studies were conducted to examine different recycling facilities of food waste. The results of the LCA study indicate that, among the different recycling methodologies currently in practice in DMC, Scenario 4 (wet and dry feed site) conduced to higher global warming potential (GWP) and higher acidification potential (AP), whereas Scenarios 2 (wet feed site 1) and 3 (wet feed site 2) resulted in the lowest impact. This is mainly due to the emission caused during the treatment stage. For eutrophication potential (EP), Scenario 1 (composting site) contributed to higher environmental impacts due to the emission of ammonia generated during the treatment process, while in case of photochemical ozone creation potential (POCP), the collection stage for all recycling facilities led to higher impacts to the environment due to the combustion of fossil fuels. This study indicates that the proper disposal of the final residues, such as solid sludge and screened materials, could aid in reducing environmental burdens.     

Efforts to develop regulations in Korea similar to the US maximum achievable control technology (MACT) regulations for hazardous waste incinerators

The development of regulations patterned after the United States’ requirement for maximum achievable control technology (MACT) to control hazardous air pollutants from major industrial sources in Korea is in progress. Current management practices and installed air pollution control devices were surveyed; emission tests and continuous emission data collected from facilities under operation were assessed considering other MACT requirements such as reporting, report keeping requirements. Emission sampling and air pollutant analysis were carried out at representative hazardous waste incinerators installed with wet-type and dry-type air pollution control devices. Korean and United States Environmental Protection Agency methods were used for sampling and analysis. The major heavy metals emitted were Zn, Ni, Pb, and Cr. The heavy metal removal efficiency of existing air pollution control devices was greater than 99%. The average mercury removal efficiency was more than 30%. Toluene; m,p-xylene; o-xylene; benzene; dichloromethane; styrene; ethylbenzene; 1,3-dichlorobenzene; and 1,2,4-trimethylbenzene were the major volatile organic compounds emitted. The emissions from field tests were compared, reviewed, and analyzed with respect to MACT regulations to check applicability. Finally, draft guidelines were suggested for effective hazardous air pollutant management in Korea.