Absorption and metabolism of the chiral isomers of fonofos in the corn and cotton plant

Root absorption of chiral phenyl-35S-fonofos in cotton and corn plants revealed stereoselective differences between the two enantiomers. (S)p-Fonofos was absorbed at a faster initial rate and to a greater extent than the (R)p enantiomer in both plant species. Approximately 40% and 62% of the applied radioactivity was absorbed into the cotton plant 12 hr after application of (R)p- and (S)p-fonofos, respectively. In the corn plant, approximately 25% and 63% of the applied (R)p- and (S)p-fonofos was absorbed in the first 12 hrs. Little qualitative or quantitative difference in plant translocation between fonofos enantiomers was observed. (R)p-fonofos was found to be metabolized to a greater extent than the (S)p enantiomer in both cotton and corn plants.     

Reviews

DESIGN ON THE LAND: the development of Landscape Architecture Norman T. Newton Belknap Harvard

COMMUNITY CENTERS AND STUDENT UNIONS Eugene D. Sternberg and Barbara E. Sternberg Van Hostrand Reinhold Company, New York.

DECISION AND CONTROL by Stafford Beer, John Wiley and Sons, Inc., New York, 1966 (3rd printing, 1970)

INDUSTRIAL DYNAMICS by Jay W. Forrester, M.I.T. Press, Cambridge, Mass., 1961. S.1O.5O.

PRINCIPLES OF SYSTEMS by Jay W. Forrester. Wright‐Allen Press, Inc., Cambridge, Mass., 1968.

PUBLIC INQUIRIES AS AN INSTRUMENT OF GOVERNMENT R.E. Wraith and G.B. Lamb George Allen & Unwin Ltd. for the Royal Institute of Public Administration, London 1971, £4.50.

SYSTEMS APPROACH AND THE CITY M.D. Mesarovic and A. Reisman (eds.) North‐Holland Publishing Co., Amsterdam and London, 1972.

SIMULATION IN THE CLASSROOM John L. Taylor and Rex Walford Penguin Books, London, 1972. 45p.

DEVELOPMENT BUILDING: THE TEAM APPROACH C.W. Griffin John Wiley & Sons, Inc. for the American Institute of Architects, New York, 1972.     

Radium isotopes in the Ulsan Bay

In order to estimate the fluxes of Ra isotopes, we measured 224Ra, 226Ra, and 228Ra activities in the Ulsan Bay mixing zone. The convex upwards curvature of the plot of Ra isotope activities versus salinity for the mixing zone suggests that Ra isotopes are supplied from particles entering the mixing zone from both the river and bottom sediments. This addition increases the estuarine flux of 226Ra and 228Ra to the outer sea by factors of 15 and 95 over the flux attributable to Ra dissolved in the riverine water alone. In order to estimate the residence time of the water in Ulsan Bay, we applied a mass balance model to the distribution of 224Ra and 226Ra activities in the Ulsan Bay mixing zone with the inflow from the Taehwa River. The obtained residence times of the waters in the Ulsan Bay were estimated to be 6.8-11.4 d. The waters in the upper part of the estuary have long residence times whereas those in the lower part, in contact with the open sea, have shorter residence times. The mean residence time of the water in the Ulsan Bay was estimated to be 9.1 d.     

Influential factors in freeway crash response and clearance times by emergency management services in peak periods

OBJECTIVE: Various factors influence the time performance of emergency management personnel when a freeway traffic crash occurs. The proper identification and prioritization of factors that contribute to emergency management services' response times and clearance times result in better usage of taxpayer resources. METHOD: Use of a proportional hazard-based Cox-regression model analyzed statewide, peak-period, traffic crash data from 1999 Ohio logs. These data included time performance measures of emergency management services. RESULTS: Traffic crash severity had the most effect on response times. Those crashes involving injuries or fatalities had up to 20% less emergency management service response times than "property damage only" crashes. Environmental factors such as weather or roadway conditions had minimal effect on response times to traffic crashes. Day of week, urban or rural area, off or opposing-lane crash location, number of vehicles involved, heavy vehicle involvement, and response time significantly affected clearance time and the resulting total time during peak periods. CONCLUSIONS: By assessing resources currently dedicated to insignificant factors, emergency management services can further improve response times to those casualties that crucially need emergency services. By accurately identifying and deciphering traffic crash severity from initial field reports, services can further improve. Moreover, improvements in crash severity prediction reduce "false alarms" for emergency services. The improvements reduce the probability of a very short response time for a property damage only crash in which initial reports implied a very severe injury. By focusing on factors that significantly reduce traffic crash clearance times on freeways in peak periods, more reductions in average delay experienced by freeway users, in fuel consumption, and in motor vehicle emissions can occur.     

Iron and organo-bentonite for the reduction and sorption of trichloroethylene

Hybrid barriers using dechlorination and immobilization were studied to remove trichloroethylene (TCE) in this study. Hybrid barriers of iron filings and organo (hexadecyltrimethylammonium, HDTMA)-bentonite were simulated in columns to assess the performance of the hybrid barriers. TCE reduction rate for the mixture of zero valent iron (ZVI) and HDTMA-bentonite was approximately seven times higher than that for ZVI, suggesting the reduction of TCE was accelerated when HDTMA-bentonite was mixed with ZVI. For the column of two separate layers of iron and HDTMA-bentonite, TCE reduction rate was nearly similar to that for ZVI alone, but the partition coefficient (Kd) was 4.5 times higher than that for ZVI only. TCE was immobilized in the first layer with HDTMA-bentonite due to sorption, and then dechlorinated in the second layer with iron filings due to reduction. The HDTMA-bentonite and minimally-desorbed HDTMA from the organo-bentonite are believed to contribute the increase in TCE concentration on iron surface so that more TCE could be available for reduction. Therefore, the incorporation of HDTMA-bentonite into ZVI not only can effectively retard the transport of chlorinated organic contaminants from landfill leachate or oil shock in subsurface environment, also can expedite the reduction rate of TCE.     

Mobilization of arsenic in groundwater of Bangladesh: evidence from an incubation study

The extensive extraction of arsenic (As)-contaminated groundwaters for drinking, household and agricultural purposes represents a serious health concern in many districts of Bangladesh. This laboratory-based incubation study investigated the sources and mechanisms of As mobilization in these groundwaters. Several incubation studies were carried out using sediments collected from the Bangladesh aquifer that were supplemented, or not, with different nutrients, followed by an analysis of the sediment suspensions for pH, ORP (oxidation-reduction potential), EC (electrical conductivity) and As and Fe(ΙΙ) concentrations. In the substrate-amended sediment suspensions incubated under anaerobic environment, there was a mobilization of As (maximum: 50–67 μg/l) and Fe(ΙΙ) (maximum: 182 μg/l), while the ORP value decreased immediately and drastically (as much as −468 mV to −560 mV) within 5–6 days. In the sediment suspensions incubated under control and aerobic conditions, no significant As mobilization occurred. The simultaneous mobilization of As and Fe(ΙΙ) from sediments is a strong indication that their mobilization resulted from the reduction of Fe oxyhydroxide by the enhanced activity of indigenous bacteria present in the sediments; this phenomenon also provides insights on the mobilization mechanism of As in groundwater. The concentrations of As in the sediments used in the incubation studies were strongly linked to the gradients of redox potential development that was stimulated by the quantity of organic nutrient (glucose) used. The penetration of surface-derived organic matter into the shallow aquifer may stimulate the activity of microbial communities, thereby leading to a reduction of iron oxyhydroxide and As release.     

Distribution characteristics of polychlorinated biphenyls in crucian carp (Carassius auratus) from major rivers in Korea

Polychlorinated biphenyls (PCBs) levels in crucian carp were determined at 20 locations along four major river systems, several small-scale rivers and a wetland in Korea. Twenty-eight congeners, ranging from tri- to hepta-CBs were detected. A gas chromatograph with a mass selective detector was used to quantify the individual PCB congeners. The objectives of this study were to investigate the levels of contamination of PCBs in freshwater fish and to observe the pattern of their distribution. The sampling locations were chosen among 31 sampling sites that are currently used as environmental residue checkpoints by the Korean Ministry of Environment. Concentrations of individual congeners ranged from not detectable (n.d.) to 0.75 ng g(-1) on a wet weight basis. The total concentrations of PCBs at each site ranged from n.d. to 5.41 ng g(-1) of wet weight. The most heavily contaminated site was the Nakdong estuary located near the Shinpyung-Janglim factory district. The PCB 153 and 138 were the principal congeners and penta- and hexa-chlorinated biphenyls comprised the main congener groups.     

Optimizing the specific surface area of fly ash-based sorbents for flue gas desulfurization

High performance sorbents for flue gas desulfurization can be synthesized by hydration of coal fly ash, calcium sulfate, and calcium oxide. In general, higher desulfurization activity correlates with higher sorbent surface area. Consequently, a major aim in sorbent synthesis is to maximize the sorbent surface area by optimizing the hydration conditions. This work presents an integrated modeling and optimization approach to sorbent synthesis based on statistical experimental design and two artificial intelligence techniques: neural network and genetic algorithm. In the first step of the approach, the main and interactive effects of three hydration variables on sorbent surface area were evaluated using a full factorial design. The hydration variables of interest to this study were hydration time, amount of coal fly ash, and amount of calcium sulfate and the levels investigated were 4-32 h, 5-15 g, and 0-12 g, respectively. In the second step, a neural network was used to model the relationship between the three hydration variables and the sorbent surface area. A genetic algorithm was used in the last step to optimize the input space of the resulting neural network model. According to this integrated modeling and optimization approach, an optimum sorbent surface area of 62.2m(2)g(-1) could be obtained by mixing 13.1g of coal fly ash and 5.5 g of calcium sulfate in a hydration process containing 100ml of water and 5 g of calcium oxide for a fixed hydration time of 10 h.     

Recovery of phosphates from wastewater using converter slag: Kinetics analysis of a completely mixed phosphorus crystallization process

A phosphorus crystallization process for recovering phosphates was developed using a completely mixed reactor and powdered converter slag as a seed crystal. This completely mixed phosphorus crystallization process achieved a stable and high phosphorus recovery: the average PO4-P removal efficiency during 200 d of operation was 87%, with a range of 70-98%. The apparent volume of the slag doubled due to crystal growth during the long-term phosphorus-removal experiments. The Ca2+ concentration, slag dosage, and temperature were found to govern the phosphorus recovery system for a given condition of pH and hydraulic retention time. The equations for the rate constant and reaction order were obtained by evaluating the model parameters. The model developed in this study was observed to successfully simulate the behavior of effluent PO4-P in a completely mixed phosphorus crystallization reactor over a wide variety of operating conditions of temperature, Ca2+ concentration, and influent PO4-P. Model investigations of design factors suggest that the completely mixed phosphorus crystallization process with influent PO4-P concentrations of less than 10 mg l(-1) could ensure effluent PO4-P concentrations of less than 0.5 and 1.0 mg l(-1) during summer and winter in Korea, respectively.     

Isolation and physiological characterization of the pentachlorophenol degrading bacterium Sphingomonas chlorophenolica

Many chlorophenols tend to persist in the environment, and they may become public health hazards. Among chlorophenols, pentachlorophenol (PCP) is a priority pollutant that has been used widely as a general biocide in commercial wood treatment. Owing to the rapid industrial growth, serious soil and water pollutions by chlorophenols has been reported in Taiwan. In this study, 10 indigenous PCP-degrading bacterial strains were isolated from a PCP-degrading mixed culture, and the potential of both the pure and mixed cultures for PCP degradation compared. Moreover, the physiological characteristics and optimum growth conditions of the PCP-degrading bacteria were investigated. One of the isolated bacterial strains with good potential for PCP degradation was characterized and identified as Sphingomonas chlorophenolica by 16S rDNA gene analysis. The result of the optimum growth temperatures revealed that this organism was a mesophile. The optimum pH for PCP removal by S. chlorophenolica was between 6.9 and 7.6. Increase in concentration of PCP has a negative effect on the biodegradation potential of S. chlorophenolica and PCP concentration above 600 mg l(-1) was inhibitory to its growth. The results of this study indicate that this S. chlorophenolica strain has a better potential for PCP degradation compared to the enriched mixed culture. The physiological characterization of the isolates also indicates the possible application of this strain for bioremediation of sites contaminated with PCP.