Heavy metal mobility in runoff water and absorption by eggplant fruits from sludge treated soil

Sewage sludge addition to agricultural lands requires judicious management to avoid environmental risks arising from heavy metal and nitrate contamination of surface water and accumulation in edible plants. A field study was conducted on a silty-loam soil of 10% slope at Kentucky State University Research Farm. Eighteen plots of 22 x 3.7 m each were separated using metal borders and the soil in six plots was mixed with sewage sludge and yard waste compost mix (SS-YW) at 15 t acre(-1), six plots were mixed with sewage sludge (SS) at 15 t acre(-1), and six unamended plots that never received sludge were used for comparison purposes. Plots were planted with eggplant, Solanum melongena L. as the test plant. The objectives of this investigation were to: 1) assess the effect of soil amendments on the transport of NO3, NH4, and heavy metals (Cd, Cr, Ni, Pb, Zn, Cu, and Mo) into surface water; 2) investigate the effect of soil amendments on heavy metal bioavailability in eggplant fruits at harvest; and 3) assess chemical and physical properties of soil following addition of soil amendments and their impact on the yield and quality of eggplant fruit. SS-YW treatments reduced runoff water by 63% while plots incorporated with sewage sludge alone reduced runoff water by 37% compared to control treatment. The SS-YW treatments transported more mineral nitrogen (NO3-N and NH4-N) in runoff water than SS treatments. Total marketable yield (lbs acre(-1)) and number of eggplant fruits were greatest in SS-YW treatments. This response may be due to improved soil porosity, water, and nutrient retention of the soil amended with SS-YW mixture. Concentrations of heavy metals in soil amended with sludge were below the U.S. Environmental Protection Agency (USEPA) limits. Chromium, Ni, Zn, and Cu were taken up by eggplant fruits but their concentrations were below the Codex Commission allowable levels.     

Detoxification of ferrocyanide in asoil–plant system

The detoxification of iron cyanide in a soil–plant system was investigated to assess the total cyanide extracted from contaminated soil and allocated in the leaf tissue of willow trees(Salix caprea). They were grown in soil containing up to 1000 mg/kg dry weight(dw) of cyanide(CN),added as ~(15)N-labeled potassium ferrocyanide and prepared with a new method for synthesis of labeled iron cyanides. CN content and ~(15)N enrichment were monitored weekly over the exposure in leaf tissue of different age. The ~(15)N enrichment in the young and old leaf tissue reached up to 15.197‰ and 9063‰, respectively; it increased significantly over the exposure and with increasing exposure concentrations(p 0.05). Although the CN accumulation in the old leaf tissue was higher, compared to the young leaf tissue(p 0.05), the ~(15)N enrichment in the two tissue types did not differ statistically. This indicates a non-uniform CN accumulation but a uniform ~(15)N allocation throughout the leaf mass. Significant differences were detected between the measured CN content and the C~(15)N content, calculated from the ~(15)N enrichment(p 0.05), revealing a significant CN fraction within the leaf tissue, which could not be detected as ionic CN. The application of labeled iron CN clearly shows that CN is detoxified during uptake by the willows. However, these results do not exclude other detoxification pathways, not related to the trees. Still, they are strongly indicative of the central role the trees played in CN removal and detoxification under the experimental conditions.     

PCDD/Fs, dioxin-like PCBs and marker PCBs in eggs of peregrine falcons from Germany

Thirty one egg samples of peregrine falcons were collected in different regions of Germany (South-West, North and East) and analysed for PCDD/Fs, PCBs and marker PCBs. Altogether, 37 PCB congeners were determined, allowing a more detailed discussion of different aspects of the relative importance of these individual congeners. For comparison with dioxin data from other studies, differences between toxic equivalency factors (TEF) have to be taken into consideration. The results of this study are discussed on the basis of WHO-TEFs for birds published in 1998. All samples showed high levels of PCDD/Fs (median of all samples: 368 pg WHO-PCDD/F-TEQ/g fat; range 137-1453) and even higher levels of PCBs (median 967 pg WHO-PCB-TEQ/g fat; range 243-7482). The upper range of these levels reach concentrations found at the beginning of the Belgian dioxin crisis when a significant reduction in hens' egg hatchability was observed. The relative contribution of PCBs to the total TEQ is on average 71% (range 55-92%) with a tendency to higher values in South-West Germany compared to different sites in East Germany or one site in northern Germany. Within a region, a wide range of contamination can be found. Even in the same cities (Stuttgart and Ludwigshafen), results derived from eggs collected in the same year (2003) varied by factors 5-10. These findings show the high degree of variation occurring even within the same kind of biological matrix. Therefore, to allow for comparison of regions or time trends, a considerable number of samples has to be analysed.     

Synthesis of polyhydroxyalkanoates in municipal wastewater treatment.

Biologically derived polyesters known as polyhydroxyalkanoates (PHAs) represent a potentially "sustainable" replacement to fossil-fuel-based thermoplastics. However, current commercial practices that produce PHA with pure microbial cultures grown on renewable, but refined, feedstocks (i.e., glucose) under sterile conditions do not represent a sustainable commodity. Here, we report on PHA production with a mixed microbial consortium indigenous to an activated sludge process on carbon present in municipal wastewaters. Reactors operated under anaerobic/aerobic and aerobic-only mode and fed primary solids fermenter liquor maintained a mixed microbial consortium capable of synthesizing PHA at 10 to 25% (w/w), while reducing soluble COD by approximately 62 to 71%. More critically, an aerobic batch reactor seeded from the anaerobic/aerobic reactor and fed fermenter liquor achieved approximately 53% PHA (w/w). Results presented suggest that environmentally benign production of biodegradable polymers is feasible. We further used PHA-rich biomass to produce a natural fiber-reinforced thermoplastic composite that can be used to offset advanced wastewater treatment costs.     

A comparison of two techniques for studying sediment desorption kinetics of hydrophobic pollutants

A comparison of two techniques (gaseous purge and vial desorption) for studying the kinetics of desorption of hydrophobic pollutants from natural sediments was conducted using identical, pre-equilibrated pollutant-sediment suspensions. Desorption profiles for the two techniques [for Lindane, Aldrin, 2,2'-dichlorobiphenyl (2,2'-DCB), 4,4'-dichlorobiphenyl (4,4'-DCB), and 2,2',6,6'-tetrachlorobiphenyl (TCB)] were then compared, based on the distribution of pollutant mass between the labile (fast) and non-labile (slow) desorption phases and the release rate constants for each phase of release. The vial desorption technique shows many practical advantages over the gaseous purge technique, including its more realistic mixing conditions, the use of an independent sample for each data point (as opposed to a calculation of a cumulative mass purged at each time point), the fact that the vials constitute a closed system and are therefore less subject to ambient contamination, and the relatively low demands of time and money for the vial technique. No consistent trends in labile rate constants or in pollutant distribution between the labile and non-labile phase were observed between the two techniques. A comparison of kinetic parameters shows much faster non-labile rate constants for the gaseous purge technique, attributed to the violent, continuous agitation employed, which likely disrupted sediment aggregates and oxidized the natural organic matter associated with the sediment. Non-labile rate constants have implications for the long-term fate of compounds adsorbed to repetitively disturbed sediments. This study suggests that the traditionally less popular vial desorption technique may yield more realistic non-labile desorption rate constants.     

Laboratory and field evaluation of crystallized DOW 704 oil on the performance of the Well Impactor Ninety-Six fFine particulate matter fractionator

Subsequent to the 1997 promulgation of the Federal Reference Method (FRM) for monitoring fine particulate matter (PM2.5) in ambient air, U.S. Environmental Protection Agency (EPA) received reports that the DOW 704 diffusion oil used in the method's Well Impactor Ninety-Six (WINS) fractionator would occasionally crystallize during field use, particularly under wintertime conditions. Although the frequency of occurrence on a nationwide basis was low, uncertainties existed as to whether crystallization of the DOW 704 oil may adversely affect a sampling event's data quality. In response to these concerns, EPA and the State of Connecticut Department of Environmental Protection jointly conducted a series of specialized tests to determine whether crystallized oil adversely affected the performance of the WINS fractionator. In the laboratory, an experimental setup used dry ice to artificially induce crystallization of the diffusion oil under controlled conditions. Using primary polystyrene latex calibration aerosols, standard size-selective performance tests of the WINS fractionator showed that neither the position nor the shape of the WINS particle size fractionation curve was substantially influenced by the crystallization of the DOW 704 oil. No large particle bounce from the crystallized impaction surface was observed. During wintertime field tests, crystallization of the DOW 704 oil did not adversely affect measured PM2.5 concentrations. Regression of measurements with crystallized DOW 704 versus liquid dioctyl sebacate (DOS) oil produced slope, intercept, and R2 values of 0.98, 0.1, and 0.997 microg/m3, respectively. Additional field tests validated the use of DOS as an effective impaction substrate. As a result of these laboratory and field tests, DOS oil has been approved by EPA as a substitute for DOW 704 oil. Since the field deployment of DOS oil in 2001, users of this alternative oil have not reported any operational problems associated with its use in the PM2.5 FRM. Limited field evaluation of the BGI very sharp cut cyclone indicates that it provides a viable alternative to the WINS fractionator.     

Model simulations for describing water transport in a landfill with bottom ash from a municipal solid waste incinerator (MSWI): model validation and scenarios.

In the present study the water movement in a bottom ash landfill from a municipal solid waste incinerator (MSWI) was investigated. The pore regime of such landfills consists of macropores (with diameter > 50 microm), which make up about two-thirds of the total porosity and micropores. The program MACRO, which describes flow through porous media and takes both macro- and micropore flows into account, was applied. The model was calibrated with a time series from the landfill Riet, near Winterthur in Switzerland. In the present study the model was recalibrated at a time series for 1 year. With this scenario the influence of an expected reduction or increase of the porosity on leachate behaviour of such landfills over a long time (> 100 years) was studied ('long-term behaviour'). It has been shown that reliable information about water percolation can only be provided by obtaining more information about the hydraulic structure of such landfills. In particular, the number of macropores and the porosity exert great influence on the water movement.     

Biodynamics of steering wheel induced facial trauma

The present study was undertaken to determine the impact biomechanics of the facial skeleton secondary to steering wheel loading. Because of the particular relevance of the zygomatic bony complex in facial trauma during motor-vehicle accidents, tests were conducted by impacting the zygoma using a vertical drop impact test system. Zygoma was impacted once onto either soft or rigid wheel surfaces at velocities of up to 6.7 m/s. Peak impact forces at the cadaver zygoma were computed from the generalized force and deformation histories using matrix transformation principles. Structural abnormalities were assessed using pre- and post-test plain radiography, two-and three-dimensional computed tomography, and defleshing techniques. At impact velocities of 1.7 to 6.7 m/s, the human cadaver zygoma did not exhibit clinically significant fractures if the peak force was below 1335 N for the soft wheel interface and 1153 N for the rigid wheel interface. Consequently, to mitigate facial injuries due to unsupported rim impact, the data from the present study suggests that the peak dynamic force should be kept within these limits.