The gas-photocatalytic degradation of trichloroethylene without water

The photocatalytic degradation of gaseous trichloroethylene (TCE) without water has been studied. The degradation products were determined to be CO₂, HCl and Cl₂, and the reaction stoichiometry, was described as

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. The degradation rate was found to be linear with 0.16 power of the illumination intensity. When the TCE concentration was low (10¹⁴ mol L⁻¹ or a little more), its degradation rate model could be considered as first order kinetics. A mechanism of valence band hole oxidation was proposed.     

Biofiltration of trimethylamine, dimethylamine, and methylamine by immobilized Paracoccus sp. CP2 and Arthrobacter sp. CP1

A biofilter using granular activated carbon with immobilized Paracoccus sp. CP2 was applied to the elimination of 10–250 ppm of trimethylamine (TMA), dimethylamine (DMA), and methylamine (MA). The results indicated that the system effectively treated MA (>93%), DMA (>90%), and TMA (>85%) under high loading conditions, and the maximum degradation rates were 1.4, 1.2, and 0.9 g-N kg⁻¹ GAC d⁻¹. Among the three different amines treated, TMA was the most difficult to degrade and resulted in ammonia accumulation. Further study on TMA removal showed that the optimal pH was near neutral (6.0–8.0). The supply of high glucose (>0.1%) inhibited TMA removal, maybe due to substrate competition. However, complete TMA degradation was achieved under the co-immobilization of Paracoccus sp. CP2 and Arthrobacter sp. CP1 (96%). Metabolite analysis results demonstrated that the metabolite concentrations decreased by a relatively small 27% while the metabolite apparently increased by heterotrophic nitrification of Arthrobacter sp. CP1 in the co-immobilization biofilter.     

Structure elucidation of the three most important toxaphene congeners by X-ray analysis

Three of the most frequently detected toxaphene components in environmental samples are the chlorobornanes 2-exo,3-endo,5-exo,6-endo,8b,8c,10a,10b-octachlorobornane (Parlar No. 26); 2-exo,3-endo,5-exo,6-endo,8b,8c,9c,10a,10b-nonachlorobornane (Parlar No. 50), and 2,2,5,5,8b,8c,9c,10a,10b-nonachlorobornane (Parlar No. 62), whose structures could not be completely elucidated by spectroscopical methods. This paper now describes the X-ray structure analysis of the three compounds and presents their exact crystal structure.     

Kinetics and mechanism of nitrite oxidation by hypochlorous acid in the aqueous phase

The rate coefficient for the reaction of nitrite with hypochlorite and hypochlorous acid has been studied using spectrophotometric measurements. The reaction rate has been determined in a wide range of H(+) concentration (5< or =-log[H(+)]< or =11). The kinetics were carried out as a function of NO(2)(-), H(+) and total hypochlorite ([HOCl](total)=[HOCl]+[ClO(-)]+[ClNO(2)]) concentrations. The observed overall rate law is described by: -d[HClO](T)dt=[a[NO(2)(-)](2)+b[NO(2)(-)]][H(+)](2)c+d[H(+)]+e[NO(2)(-)][H(+)](2)[HOCl](total)At T=298 K and in Na(2)SO(4) at an ionic strength (I=1.00 M), we obtained using a nonlinear fitting procedure: a=(1.83+/-0.36)x10(7) s(-1), b=(1.14+/-0.23)x10(5) Ms(-1), c=(1.12+/-0.17)x10(-13) M, d=(1.43+/-0.29)x10(-6) M(2) and e=(1.41+/-0.28)x10(3) M where the errors represent 2sigma. According to the overall rate law, a/b=k(1)/k(3), b/e=k(3), c=K(w), d/c=K(a), d=K(a)K(w) and e=K(1)K(a). In Na(2)SO(4) at an ionic strength (I=1.00 M), the values of K(1) and K(a) are (1.1+/-0.1)x10(-4) and 1.28x10(7) M(-1), respectively. A mechanism is proposed for the NO(2)(-) oxidation which involves the reversible initial step: NO(2)(-)+HOCl left harpoon over right harpoon ClNO(2)+OH(-) (K(1)), while ClNO(2) undergoes the two parallel reactions: attack by NO(2)(-) (k(1)) and hydrolysis (k(3)). ClNO(2) and N(2)O(4) are proposed as important intermediates as they control the mechanism. The rate coefficients k(1) and k(3) have been determined at different ionic strengths in NaCl and Na(2)SO(4). The influence of the ionic strength and ionic environment has been studied in this work.     

Properties of the 2,3,7,8-TCDD receptor- a QSAR approach

The Ah or 2,3,7,8-TCDD receptor protein plays an important role in mediating the biologic, toxic and genotoxic effects of aryl and halogenated aryl hydrocarbons. An assessment of the physicochemical parameters which facilitate ligand: receptor interactions was determined by multiple parameter linear regression analysis of the relative receptor binding affinities of a series of 7-substituted-2,3-dichlorodibenzo-p-dixoins (Eq 1), 8-substituted-2,3-di (Eq. 2) and 2,3,4-trichlorodibenzofurans (Eq 3). The results demonstrate that substituent lipophilicity (π) and molecular volumes were

(Eq.1)

log (I/EC₅₀) = 1.24 π + 6.10

(Eq.2)

log (I/EC₅₀) = 1.10 π + 5.19

(Eq.3)

log (I/EC₅₀) = 1.09 π + 5.77

the major determinant factors governing interactions between the rat hepatic cytosolic receptor protein and the diverse substituted ligands. It has been shown that there are marked differences in species sensitivity to 2,3,7,8-TCDD (i.e. guinea pig > rat maice > hamster) although hepatic receptor levels in these species are comparable. QSAR analysis of the receptor binding EC₅₀ data for the 7-substituted-2,3-dichlorodibenzo-p-dioxins using rat (Eq. 1), mouse (Eq. 4), guinea pig (Eq. 5) and hamster (Eq. 6) hepatic cytosol demonstrated that there were significant differences in these equations. However it was also noted that

(Eq.4)

log (I/EC₅₀) = 0.95 + 0.93 E_s + 5.28

(Eq.5)

log (I/EC₅₀) = 0.94 + 0.579 σ_p + 6.13

(Eq.6)

log (I/EC₅₀) = 0.70 + 1.227 σ_p + 6.38

physicochemical factors which are important for ligand-receptor interactions were identical for the most sensitive (guinea pig) and least sensitive (hamster) species. These results indicate that events which follow the initial ligand-receptor interaction must be the major factors which determine species sensitivity to 2,3,7,8-TCDD.     

Biotransformation of ethinylestradiol by microalgae

The capability of biotransformation of 11 microalgae strains was tested on ethinylestradiol (EE). Seven strains were ineffective whilst Selenastrum capricornutum, Scenedesmus quadricauda, Scenedesmus vacuolatus and Ankistrodesmus braunii biotransformed the substrate. EE was converted by S. capricornutum in three products (ethinylestradiol glucoside, 3-β-d-glucopyranosyl-2-hydroxyethinylestradiol, and 3-β-d-glucopyranosyl-6β-hydroxyethinyl estradiol) in 40%, 5%, and 5% yields, respectively. S. quadricauda transformed EE into 17-ethinyl-1,4-estradien-10,17β-diol-3-one (12%) and A. braunii transformed EE into 6--hydroxy-ethinylestradiol (25%).

It is noteworthy that EE is converted in 92% yield in ethinylestradiol glucoside by S. capricornutum when using optimal algal density conditions.     

Light-induced disappearance of nitrite in the presence of iron (III)

Understanding of rapid disappearance of nitrite in natural waters and its impact on nitrogen natural cycling has remained limited. We found that NO2- disappeared rapidly in pH 3.2 aqueous Fe(III) solutions both in sunlight and in 356 nm light. Quantum yields of the NO2- loss at 356 nm were 0.049-0.14 for initial levels of 10-80 microns NO2- and 200 microns Fe(III). The NO2- loss (at 356 nm) followed apparent first-order kinetics. The rate constants were 1.3 x 10(-3) (40 microns NO2-) and 4.1 x 10(-4) s-1 (80 microns NO2-) for 100 microns Fe(III), and 2.3 x 10(-3) (40 microns NO2-) and 7.5 x 10(-4) s-1 (80 microns NO2(-1)) for 200 microns Fe(III) (t1/2 = 8.7, 27.9, 5.1, and 15.3 min, respectively). The rate constants were directly proportional to [Fe(III)]0 and inversely proportional to [NO2-]0. Agreement between the rate constants obtained experimentally and those calculated mechanistically supports the hypothesis that NO2- was oxidized to NO2 by .OH radicals from photolysis of FeOH2+ complexes, and at high [NO2-]0 (e.g., 80 microns) relative to [Fe(III)]0, hydrolysis of NO2 or N2O4 to form NO3- and NO2- could be significant. This study showed that light and Fe(III)-induced oxidation of NO2- (rate = approximately 10(-1)-10(-2) microns s-1) was more rapid than its direct photolysis (rate = approximately 10(-4) microns s-1), and the photolysis could be a significant source of .OH radicals only in cases where the Fe(III) level is much lower than the NO2- level ([Fe(III)]/[NO2-] < 1/80). This study suggests that the light and Fe(III)-induced oxidation of NO2- would be one potential important pathway responsible for the rapid transformation of NO2- in acidic surface waters, especially those affected by acid-mine drainage or volcanic activities. This study also may be of interest for modeling certain acidic atmospheric water environments.     

Enantioselective determination of persistent and partly degradable toxaphene congeners in high trophic level biota

Enantiomer separation of chiral toxaphene components in biological samples was studied by application of different chiral stationary phases based on modified cyclodextrins. Several pairs of enantiomers were resolved on permethylated beta-cyclodextrin (beta-PMCD), among them 2-endo,3-exo,5-endo,6-exo,8,8,9,10-octachlorobornane (B8-1412), which was not enantiomerically resolved on tert-butyldimethylsilylated beta-cyclodextrin (beta-BSCD). The latter column was applied to determine the enantiomer ratios (ERs) of 2-endo,3-exo,5-endo,6-exo,8,8,10,10-octachlorobornane (B8-1413 or P-26) in brain tissue of three seal species. The ER of B8-1413 (P-26) in brain was virtually racemic as well as those of the two persistent and chiral components of technical chlordane, 1-exo,2,2,4,5,6,7,8,8-octachloro-3a,4,7,7a-tetrahydro-4,7-metha noindane (trans-nonachlor III or MC 6) and 1-exo,2-endo,3-exo,4,5,6,8,8-octachloro-3a,7,7a-tetrahydro-4,7- methanoindane (U82). In contrast, B8-1412 and 2-exo,5,5,8,9,9,10,10-octachlorobornane (B8-2229 or P-44) were significantly enantiomerically enriched in several samples of high trophic level biota. 2,2,5,5,8,9,9,10,10-Nonachlorobornane (B9-1025 or P-62), a chlorobornane metabolisable by seals and the presumable precursor of B8-2229 (P-44), was also enantiomerically enriched in seal blubber. These results confirm the assumption that some less persistent toxaphene components may be significantly degraded in biological samples. Enantioselective gas chromatography provides the information that such a degradation is happening by the characteristic change of the ratio of the two enantiomers in the respective tissues.     

Synchronous-scan fluorescence spectra of Chlorella vulgaris solution

The characterization of the Chlorella vulgaris solution was carried out using synchronous-scan spectroscopy. The range of concentration of algae and Fe(III) in aqueous solutions were 5 × 10⁸–8 × 10⁹ cells l⁻¹ and 10–60 μM, respectively. Effective characterization method used was synchronous-scan fluorescence spectroscopy. The wavelength difference (Δλ) of 90 nm was maintained between excitation and emission wavelengths; 90 nm was found to be the best Δλ for effective characterization of Chlorella vulgaris solution with or without quencher species (e.g., Fe(III), humic acid (HA)) for the first time. The peak was observed at about EX 236.6 nm/EM 326.6 nm for synchronous-scan fluorescence spectra. The fluorescence quenching of algae in system of algae–Fe(III)–HA was studied using synchronous-scan spectroscopy for the first time. Fe(III) was clearly the effective quencher. The relationship between I₀/I (quenching efficiency) and c (concentration of Fe(III) added) was a linear correlation for the algae solution with Fe(III). Also, Aldrich humic acid was found to be an effective quencher. pH effect on synchronous-scan fluorescence intensity of algal solution with Fe(III) and/or HA was evident.     

Climate simulations using the GCRC 2-D zonally averaged statistical dynamical climate model

The two-dimensional statistical dynamical climate model, recently developed at the Global Change Research Center (GCRC 2D climate model) is presented and discussed. The model solves the 2-D primitive equations in finite difference form (mass continuity, Newton's second law, and the first law of thermodynamics) for the prognostic variables zonal mean density, zonal mean zonal velocity, zonal mean meridional velocity, and zonal mean temperature on a grid that has 18 nodes in latitude and 9 vertical nodes (plus the surface). The equation of state, p = ρRT and an assumed hydrostatic atmosphere, δp = −ρgδz, are used to diagnostically calculate the zonal mean pressure and vertical velocity for each grid node, and the moisture balance equation is used to estimate the precipitation rate.

The performance of the model at simulating the two-dimensional temperature, zonal winds, and mass stream function is discussed here. The strengths and weaknesses of the model are highlighted and plans for future model experiments and improvements are given. The parameterization of the transient eddy fluxes of heat and momentum developed by Stone and Yao (1987 and 1990) are used with small modifications. These modifications are shown to improve the performance of the model at simulating the observed climate system as well as increase the model's computational stability.     

Possible involvement of frontier (π) electrons in the metabolism of poly-chlorinated biphenyls (PCBs)

The electron density, at each carbon atom, of the highest occupied π orbital of thirteen polychlorinated biphenyl (PCB) and one polychlorinated dibenzofuran (PCDF) molecules were calculated and the result was compared with their in vitro and/or in vivo metabolism. We noted that 1. the carbon position at which the frontier electron density was highest was most readily hydroxylated or sulfonated, 2. if the carbon with the highest frontier (π) electrons was occupied by chlorine, either a replacement occurred or the carbon with the next highest electron density was activated for metabolism, 3. due to steric hinderance ‘ortho’ carbons in PCBs were least preferred for such reactions inspite of possessing favorable electron density, 4. this was applicable to both phenobarbitol (PB) - type and 3-methyl cholanthrene (3 MC) - type PCB inducers. Frontier (π) electron density could be an easy guide for understanding the metabolic products of persistent and toxic environmental pollutants in vitro or in vivo and in understanding their environmental fate.     

Single-particle characterization of atmospheric aerosols collected at Gosan, Korea, during the Asian Pacific Regional Aerosol Characterization Experiment field campaign using low-Z (atomic number) particle electron probe X-ray microanalysis

A quantitative energy-dispersive electron probe X-ray microanalysis (ED-EPMA), namely low-Z (atomic number) particle EPMA, was used to characterize the chemical compositions of the individual aerosol particles collected at the Gosan supersite, Jeju Island, Korea, as a part of the Asian Pacific Regional Aerosol Characterization Experiment (ACE-Asia). On 4-10 April 2001 just before a severe dust storm arrived, seven sets of aerosol samples were obtained by a seven-stage May cascade impactor with a flow rate of 20 L/min. Overall 11,200 particles on stages 1-6 with cutoff diameters of 16, 8, 4, 2, 1, and 0.5 microm, respectively, were examined and classified based on their secondary electron images and X-ray spectra. In general, sea salt particles were the most frequently encountered, followed by mineral dust, organic carbon (OC)-like, (NH4)2SO4/NH4HSO4-containing, elemental carbon (EC)-like, Fe-rich, and K-rich particles. Sea salt and mineral dust particles had a higher relative abundance on stages 1-5, whereas OC-like, (NH4)2SO4/NH4HSO4-containing, Fe-rich, and K-rich particles were relatively abundant on stage 6. The analysis on relative number abundances of various particle types combined with 72-hr backward air mass trajectories indicated that a lot of reacted sea salt and reacted mineral dust (with airborne NOx and SO2 or their acidic products) and OC-like particles were carried by the air masses passing over the Yellow Sea (for sample "10 April") and many NH4HSO4/ (NH4)2SO4-containing particles were carried by the air masses passing over the Sea of Japan and Korea Strait (for samples "4-9 April"). It was concluded that the atmosphere over Jeju Island was influenced by anthropogenic SO2 and NOx, organic compounds, and secondary aerosols when Asian dust was absent.     

Concentrations and accumulation patterns of organochlorine contaminants in the blubber of harbour porpoises, Phocoena phocoena, from the coast of Newfoundland, the Gulf of St Lawrence and the Bay of Fundy/Gulf of Maine

Concentrations of 99 organochlorine compounds were measured in the blubber of 196 harbour porpoises, Phocoena phocoena, killed in commercial gill net fisheries in the western North Atlantic. PCBs and chlorinated bornanes (CHB) were the dominant contaminants in all porpoises. Mean concentrations (with standard deviations) of PCBs and CHBs from the three regions were as follows: Bay of Fundy/Gulf of Maine, PCB males 17.3 +/- 11.2 microg/g, PCB females 11.4 +/- 4.8 microg/g, CHB males 11.5 +/- 6.6 microg/g, CHB females 8.4 +/- 5.3 microg/g; Gulf of St Lawrence, PCB males 10.6 +/- 5.4 microg/g, PCB females 7.2 +/- 3.9 microg/g, CHB males 14.1 +/- 8.8 microg/g, CHB females 9.0 +/- 6.3 microg/g; southeast Newfoundland, PCB males 5.2 +/- 2.5 microg/g, PCB females 5.5 +/- 4.4 microg/g, CHB males 7.0 +/- 2.2 microg/g, CHB females 5.5 +/- 3.0 microg/g. The relative composition of the major contaminant groups found in male and female harbour porpoise blubber from the three locations varied. In order of decreasing concentration, porpoises from Fundy/Maine had PCBs > CHB > DDT > chlordanes (CHL), whereas Gulf of St Lawrence and Newfoundland porpoises had CHB > PCB > DDT > CHL. Significant increases with age were observed for most contaminants in male harbour porpoises, and significant decreases were observed in females. Females lose about 15% of their contaminant burden per birth. PCB and DDT levels in porpoises from the Bay of Fundy are significantly lower than those recorded in the 1970s.     

Indirect identification of an unstable intermediate in γ-HCH degradation by Pseudomonas paucimobilis UT26

While a postulated intermediate, 1,3,4,5-tetrachlorocyclohexa-1,4-diene(1,4-TCDN), is one of the key-compounds in γ-hexachlorocyclohexane(γ-HCH) degradation by Pseudomonas paucimobilis UT26(UT26), it has neither been isolated nor identified yet. Thus, an indirect identification was attempted to demonstrate its existence by a chemical oxidation of the microbial degradation products in situ.

1,2,4,5-Tetrachlorobenzene(1,2,4,5-TeCB) was newly produced by the chemical oxidation with hydrogen peroxide under iron(II) of W medium containing degradation products in situ of γ-1,3,4,5,6-pentachlorocyclohexene(γ-PCCH) by Escherichia coli MV1184(E. coli) which possesses the dehydrochlorinating activity of UT26. The chemical oxidation required the preceding enzymatic reactions to γ-PCCH by E. coli for the production of 1,2,4,5-TeCB. In facts, 1,2,4,5-TeCB was not produced from γ-PCCH by either of the chemical or enzymatic reaction alone.

Considering these results and the fact that hydrogen peroxide is known to dehydrogenate chemical compounds, it was concluded that 1,2,4,5-TeCB was produced directly from the unstable intermediate, 1,4-TCDN, on yielded from γ-PCCH by an enzymatic dehydrochlorination.     

Removal of carotene-like colored compounds by liquid-liquid extraction during polycyclic aromatic hydrocarbons analysis of plant tissue

Plants contain a wide variety of chemicals, some of which may have similar chromatographic behavior to polycyclic aromatic hydrocarbons (PAHs). During solid phase extraction (SPE) with Si-gel for instance, the co-elution of carotene-like colored compounds with PAHs has been observed. In this paper, liquid–liquid extraction was applied for the separation and subsequent analysis of PAHs from plant extracts. PAHs containing 2–6 rings, which include naphthalene, phenanthrene, pyrene, benzo[a]pyrene and benzo[ghi]perylene, were used as representative target chemicals. Carotene-like compounds extracted from Komatsuna (Brassica campestris) shoot by acetone followed by Si-gel treatment were incorporated as undesired components in the model matrix. Results showed the feasibility of employing either acetonitrile or 2% (w/v) KOH–methanol as solvents for high PAHs recovery and low extraction of colored fraction. For acetonitrile, 86.9–93.5% of each PAH could be recovered after three extraction cycles (relative standard deviation, RSD < 1.6%) with only about 10% co-extraction of colored fraction. For 2% KOH–methanol, PAHs recoveries ranging from 79.3% to 83.1% after five cycles (RSD < 1.5%) were achieved while the percent extraction of colored fraction was also low at 10%. The relatively higher selectivity of the solvents for PAHs over the colored fraction as well as the solubility of the matrix solution in the solvent may have contributed to these results. On this basis, liquid–liquid extraction is very useful for the pre-treatment of plant extracts for PAHs analysis.     

Probabilistic risk assessment for personal exposure to carcinogenic polycyclic aromatic hydrocarbons in Taiwanese temples

To assess how the human exposure to airborne carcinogenic polycyclic aromatic hydrocarbons (PAHs) during working in or visiting a typical Taiwanese temple, we present a probabilistic risk model, appraised with reported empirical data. Two approaches are applied, one based on animal-derived benzo[a]pyrene (B[a]P) toxic equivalents (B[a]P(eq)) of individual PAHs and one is assumed that the potency of PAH mixtures is linked to their B[a]P level. The model integrates probabilistic exposure profiles of total-PAH and particle-bound PAH levels inside a temple from a published exploratory study with probabilistic incremental lifetime cancer risk (ILCR) models taking into account inhalation and dermal contact pathways, to quantitatively estimate the exposure risks for three age groups of adult, adolescent, and child. Risk analysis indicates that 90% probability inhalation ILCRs for three age groups have orders of magnitude around 10(-7)--10(-6); whereas for the dermal contact ILCRs ranging from 10(-5) to 10(-4), indicating high potential cancer risk. All 90% probabilities of B[a]P- and B[a]P(eq)-based total ILCRs are larger than 10(-6), indicating unacceptable probability distributions for three age groups. Sensitivity analysis indicates that to increase the accuracy of the results efforts should focus on a better definition of probability distributions for inhalation cancer slope factor, inhalation rates, and particle-bound PAH-to-skin adherence factor. We estimate risk-based visiting frequency advice for adult, adolescent, and child to a temple ranging from 5 to 7, 17 to 23, and 48 to 65 year(-1), respectively, based on an average 3h residence time.     

Interaction of bisphenol A with rat hepatic cytochrome P450 enzymes

The effect of bisphenol A (BPA) on the kinetics of cytochrome P450 (P450)-dependent monooxygenases in rat liver microsomes was studied. Testosterone 16beta-hydroxylase (TS16BH) and testosterone 2alpha-hydroxylase (TS2AH) activities were extensively inhibited by BPA at 100 microM (69% and 74%, respectively). The inhibition type was mixed for both P450-dependent monooxyganases. The Ki of TS16BH and TS2AH from Lineweaver-Burk plots were 25.9 and 24.9 microM, respectively. The activities of acetanilide 4-hydroxylase (AA4H), 7-ethoxycoumarin O-deethylase (ECOD), bufuralol 1'-hydroxylase (BF1'H), chlorzoxazone 6-hydroxylase (CZ6H) and testosterone 6beta-hydroxylase (TS6BH) were also effectively inhibited by BPA at 100 microM (43-52%). The inhibition type of these P450-dependent monooxygenases was mixed or uncompetitive, and the K(i)s (50.5-88.5 microM) were higher than those of TS16BH and TS2AH. By contrast, the values of IC50 and Ki of testosterone 7alpha-hydroxylase (TS7AH) and lauric acid omega-hydroxylase (LAOH) for BPA were >1000 microM. These results suggest that BPA interacts with rat hepatic CYP1A2, CYP2A2, CYP2B2, CYP2C11, CYP2D1, CYP2E1 and CYP3A2 in vitro.     

Assessment of toxicity of a glyphosate-based formulation using bacterial systems in lake water

A new Aeromonas bioassay is described to assess the potential harmful effects of the glyphosate-based herbicide, Roundup^®, in the Albufera lake, a protected area near Valencia. Viability markers as membrane integrity, culturability and β-galactosidase production of Aeromonas caviae were studied to determine the influence of the herbicide in the bacterial cells. Data from the multifactor analysis of variance test showed no significant differences (P > 0.05) between A. caviae counts of viability markers at the studied concentrations (0, 50 and 100 mg l⁻¹ of glyphosate).

The effects of Roundup^® on microbial biota present in the lake were assessed by measuring the number of indigenous mesophilic Aeromonas in presence of different amounts of the herbicide at 0, 50 and 100 mg l⁻¹ of glyphosate. In samples containing 50 and 100 mg l⁻¹ of glyphosate a significant (P < 0.05) increase in Aeromonas spp. counts and accompanying flora was observed.

The acute toxicity of Roundup^® and of Roundup^® diluted with Albufera lake water to Microtox^® luminescent bacterium (Vibrio fischeri) also was determined. The EC₅₀ values obtained were 36.4 mg l⁻¹ and 64.0 mg l⁻¹ of glyphosate respectively. The acidity (pH 4.5) of the herbicide formulation was the responsible of the observed toxicity.     

TCDD (2,3,7,8-tetrachlorodibenzo-P-dioxin) causes reduction in glucose uptake through glucose transporters on the plasma membrane of the guinea pig adipocyte.

A single dose of 2,3,7,8-TCDD (1 micrograms/kg, i.p. injection) resulted in a significant decrease in cellular 3-O-methyl-[3H]-glucose uptake by guinea pig adipose tissue and pancreas after 24 hours. An in situ tissue culture study in which pieces of adipose tissue were incubated with 10(-8)M TCDD showed a time-dependent decrease in glucose uptake. Reconstitution of adipocyte plasma membrane from tested or control animals into artificial liposomes also resulted in this difference in glucose uptake. Binding of [3H]-cytochalasin B, a specific inhibitor of glucose transporter proteins, was significantly lower in acetone-ether powder preparations of TCDD-treated adipose tissue than from controls, suggesting that the total titer of these proteins is decreased by TCDD. Finally, the relevance of these results to glucose or lipid metabolism was tested. Lipoprotein lipase (LPL) activity of guinea pig adipose tissue was decreased after 8 hours of in situ incubation with TCDD indicating that glucose uptake was depressed at an earlier time point. These findings may contribute to a better understanding of dioxin-induced "wasting syndrome".     

Precipitation of swine and cattle manure phosphorous using limestone dust

The effectiveness of SPS and PULPRO, fine limestone dusts, in precipitating swine and dairy manure phosphorous (P) was determined in the laboratory. Both manures were sieved before being treated with limestone, to reproduce the treatment of mechanically separated manure and to observe the precipitation effect of limestone without that of the large manure solid particles. P precipitation was optimized by varying precipitation conditions (propeller blade speeds, mixing time and limestone levels) and limestone particle size. P precipitation was optimized using a propeller blade mixing speed of 0.3 m s(-1) for at least 5 minutes, using 3% limestone (dry limestone mass over wet manure mass). In terms of particle size, PULPRO 20 (limestone with a particle size of 0.02 mm) produced the most P precipitation and the smallest volume and mass of sludge, as compared to PULPRO 10, PULPRO 3 and SPS (limestone with a particle size of 0.01, 0.003 and 0.3 to 0.003 mm, respectively). For both 9.5% TS (total solids) dairy and 8.8% TS swine manure, mechanical separation followed by limestone precipitation concentrated 90% of manure TS and TP in a sludge volume representing 45% of the initial raw manure mass.