Improved dissipation kinetic model to estimate permissible pre-harvest residue levels of pesticides in apples

Prediction of residual concentrations of applied pesticides during the pre-harvest period may be required to ensure the safety of agricultural products. In this study, time-dependent dissipation trends of carbaryl (CB), kresoxim-methyl (KM), flubendiamide (FB), flufenoxuron (FN), bitertanol (BT), and chlorantraniliprole (CN) applied to apples at recommended and threefold greater doses were modeled to estimate pre-harvest residue limit concentrations (C_PHRL) indicating permissible pesticide concentrations during the pre-harvest period. Double-exponential (DE) model results best fit the dissipation trends of all tested pesticides (correlation coefficients of 0.91–0.99) compared to zero-, first-, and second-order models. Among the pesticides examined, CB half-lives in apples of 2.9 and 6.6 days were the shortest, while those of FN (21.1–32.7 days) were the longest. The C_PHRL values for each pesticide in apples were estimated with DE model parameter values and could be used to determine harvest dates for safe apples with pesticide concentrations below their maximum residue limits. Application of the DE model for C_PHRL calculation provides more accurate information for farmers to produce agricultural products safe from pesticide residues.     

Agri-food-energy system metabolism: a historical study for northern France,from nineteenth to twenty-first centuries

Regional Environmental Change - We reconstruct the metabolism of cereal grain production and processing systems in the Seine river basin at four time points between 1860 and 2010 in terms of...     

Correction to: Status and trends of circumpolar peregrine falcon and gyrfalcon populations

While collating contributions and comments from 36 researchers, the coordinating authors accidentally omitted Dr. Suzanne Carrière from the list of contributing co-authors. Dr. Carrière’s data are described in Tables 1 and 3, Figure 2 and several places in the narrative. The new author list is thus updated in this article.     

Ultra trace simultaneous determination of 50 polycyclic aromatic hydrocarbons in biota using pMRM GC-MS/MS

Abstract

A saponification extraction method with gas chromatography pseudo-MRM (pMRM) mass spectrometry detection was developed for the determination of 50 total polycyclic aromatic hydrocarbons (TPAH50, a combination of parent and alkylated homologues) in biota. The method was aimed at monitoring and identification of potential TPAH contaminants in bitumen impacted environments. Alkylated PAHs were determined by multi-level, quantitative calibration using parent PAHs. The developed and thoroughly validated method required only one injection for TPAH50 analysis which represents significant saving of time and expensive authentic alkylated standards. The current method was tested with certified reference mussel tissue NIST 1974c and performed well. In a comparison study, the method reached a limit of quantitation (LOQ) for the TPAH50 between 0.1 and 0.2?ng g^?1, while the QuEChERs enhanced matrix removal – lipid (EMR) kit produced by Agilent showed an LOQ of 5–10?ng g^?1. The current method relied on response factors (RF) for the quantitation of alkylated PAHs determined against parent PAHs. These RFs were shown to be stable and consistent over the course of 1 year, during which over 200 routine environmental biota monitoring samples were analyzed. The environmental biota monitoring samples analyzed include muscle, carcass and liver, with an average total PAH50 concentration of 13, 90 and 135?ng g^?1, respectively. Results show significant differences in the distributions of 1 ringed, 2 ringed, 3 ringed, 4 ringed, and 5+ ringed TPAHs between the types of biota samples.     

Analysis of gas flow behavior in an annular fluidized-bed reactor for polystyrene waste treatment

The characteristics of bubble properties and the chaotic flow behavior of gas were investigated in an annular fluidized bed (0.102 m in inner diameter and 2 m in height) because the behavior of gas flow in such a reactor is one of the important factors governing reactor operation, reactor performance, and the reaction itself. Pressure fluctuations as a state variable for the analysis of gas flow behavior were measured and analyzed. Bubble properties were determined by adopting the cross-correlation function of pressure fluctuations. The resultant chaotic flow behavior of gas was interpreted by means of chaotic parameters such as the Kolmogorov entropy. It was found that the Kolmogorov entropy could be utilized effectively to explain the nonlinear dynamic behavior of gas-solid flow in the annular fluidized bed. The pierced length and rising velocity of bubbles increased with increasing gas velocity, bed temperature, and particle size of the bed material. The bubble frequency increased with increasing gas velocity and bed temperature, while it decreased with increasing particle size of the bed material. Correlations to predict the bubble properties in annular fluidized-bed reactors were suggested.     

Comparative study on leachate in closed landfill sites: focusing on seasonal variations

This article is intended to provide background information on leachate management in closed landfill sites based on a comparison of two landfill sites and the identification of leachate characteristics depending on the final cover and the season. Site S is older and has no final cover, while site J is younger and has final capping. The results of leachate analysis from the two landfills show that the biological oxygen demand to chemical oxygen demand ratio decreases below 0.1 to the range 0.05–0.07 for site S, whereas the ratio at site J was in the range 0.08–0.55. The inorganic nitrogen concentration was in the range 169.9–386.1 mg/l with an average of 265.2 mg/l at site S. Ammonia nitrogen accounted for 98.9% of the total nitrogen. The absence of a final cover on closed landfill sites may contribute to the stabilization of such landfills due to flushing. The nitrogen content at landfill S dropped in the summer, whereas it decreased in the fall at site J. A higher fluctuation in the pollutant levels of organic matters and nitrogen at the younger landfill site was observed, compared to the older site, even though the younger site had final capping. Therefore, intensive leachate management should be arranged at the early stages after closing for proper treatment. Specifically, nitrogen management of leachate is a critical factor in treatment operations.     

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.     

Decision support for prioritizing energy technologies against high oil prices: A fuzzy analytic hierarchy process approach

To provide national energy security in the 21st century, establishing a long-term strategic energy technology development is essential through selection and specialization. We established a strategic energy technology roadmap (ETRM) taking economic spin-offs, commercial potential, inner capacity, and technical spin-off into account. In this research, we suggest an integrated multi-criteria decision making (MCDM) approach, which is composed of more than two criteria as the assessment of the optimal alternatives and solutions in the real world with the fuzzy theory and analytic hierarchy process (AHP), to prioritize the weights of energy technologies of ETRM as we allocate R&D budget using a fuzzy analytic hierarchy process. Building technology is the most preferred technology in the sector of energy technologies against high oil prices. And the coal technology and transportation technology follows and take the 2nd and 3rd place with the fuzzy AHP approach.     

Reducing security vulnerabilities for critical infrastructure

In this paper, we show the need for improved Process Control System (PCS) security, and describe some of the promising research areas in PCS security. One implementation of PCS in critical infrastructure and factory automation is a supervisory, control, and data acquisition (SCADA) system, a real-time industrial process control system which centrally monitors and controls remote and/or local processes utilizing plant, equipment, or devices (such as switches, valves, pumps, relays, etc.) while collecting and logging field data. Current SCADA systems are distributed, networked, and dependent on open protocols for the internet, which are exposed to remote cyber terrorism. They are particularly vulnerable to unauthorized access. We give some examples of SCADA processes with natural gas control systems in USA and the Ubiquitous Sensor Network (USN) in Korea. We also examine a representative vulnerability and corresponding measures for security, and present an example of concrete measures for the security of mass transportation as a critical infrastructure.     

Behavior of buoyancy and momentum controlled hydrogen jets and flames emitted into the quiescent atmosphere

As an effort to improve the prediction of hydrogen dispersion in the atmosphere, effects of buoyancy acting on the hydrogen jets formed by releasing from high pressure vessels are investigated analytically and experimentally. For the analytical study, an integral analysis for buoyant jets and flames is carried out to yield the closed formula describing the jet and flame shapes, including their trajectory and horizontal and vertical lengths corresponding to the critical concentrations. Because the density of hydrogen after releasing from high pressure storage conditions is much close to that of helium than that of hydrogen at room temperature, helium is used as the hydrogen surrogate for the buoyant jet experiments, which were performed by visualizing the jet dispersing in the atmosphere up to the jet Reynolds number Re ～ 2400. The trajectories obtained by the integral analysis and experiments agree relatively well until the transition to turbulence occurs. A further estimate for jets and flames is made by using the integral analysis as a preliminary design to the experiments involving a much greater hydrogen release. Once the comparative investigation of the larger scale experiments with the integral analysis, we anticipate that a more universal hydrogen jet and flame data can be obtained, which perhaps leads to a better safety distance of hydrogen stations.