Evaluation of the persistence of micropollutants through pure-oxygen activated sludge nitrification and denitrification.

The persistence of pharmaceuticals, hormones, and household and industrial chemicals through a pure-oxygen activated sludge, nitrification, denitrification wastewater treatment facility was evaluated. Of the 125 micropollutants that were tested in this study, 55 compounds were detected in the untreated wastewater, and 27 compounds were detected in the disinfected effluent. The persistent compounds included surfactants, fire-retardant chemicals, pesticides, fragrance compounds, hormones, and one pharmaceutical. Physical-chemical properties of micropollutants that affected partitioning onto wastewater solids included vapor pressure and octanol-water partition coefficients.     

HCHs and DDTs in sediment-dwelling animals from the Yangtze Estuary, China

HCHs and DDTs in sediment-dwelling animals including mollusks and crabs from the Yangtze Estuary were determined by GC-ECD. Levels of t-HCH were in the range of 1.2-5.5 ng g(-1) and averaged 3.5 ng g(-1) in mollusks, while t-DDT concentrations ranged from 26.0 to 68.8 ng g(-1), with a mean of 34.5 ng g(-1). In crabs t-HCH concentrations varied from 2.0 to 25.7 ng g(-1) and averaged 13.8 ng g(-1), whereas the concentrations of t-DDT were in the range of 1.5-24.8 ng g(-1) with a mean value of 5.9 ng g(-1). The HCHs and DDTs levels depend on geographical position and sources, showing the high levels at fresh water area in the estuary, such as XP, CM and LHK sites, and lower at brackish water area, such as FX site, and little difference between species. Results also indicate there was no significant relationship between t-HCH (t-DDT) concentrations and lipid contents both in mollusks and crabs because of non-equilibrium state under a specific estuarine dynamics; smaller individuals accumulated more HCHs and DDTs than larger individuals of mollusks at LHK site, showing different uptake rate for these pesticides; moreover, HCHs and DDTs levels were lower in female crab bodies than male crab bodies suggesting that the release of spawning. BSAFs (Biota- Sediment Accumulation Factors) from sediment-dwelling animals for HCHs and DDTs show a significant "one high with two low" and "one low with two high" effect in the Yangtze Estuary.     

Evaluating the role of desorption in bioavailability of sediment-associated contaminants using oligochaetes, semipermeable membrane devices and Tenax extraction

The success of the rapidly desorbing fraction as an available fraction was challenged by using sediment ingesting and non-ingesting oligochaetes (Lumbriculus variegatus) together with passive samplers (semipermeable membrane devices, SPMDs) in accumulation and kinetic modelling exercises for carbon-14 labelled model compounds (pyrene, benzo[a]pyrene and 3,4,3',4'-tetrachlorobiphenyl). Passive samplers clearly produced lower uptake rate constants and steady state factors than either of the oligochaete treatments when residue concentrations were based on animal lipid or total SPMD weight. The rapidly desorbing chemical fractions in sediments did not show a significant relationship with the biota sediment accumulation factors or SPMD accumulation factors. A distinctly better relationship was observed between the accumulation factors and the desorption rate constants. The results support the assumption that desorption plays an important role in bioavailability, although animal behaviour and the diffusional limitations of hydrophobic contaminants in sediment together probably affect the actual available pool.     

Anthropogenic metal enrichment of snow and soil in north-eastern European Russia

Trace metal composition of winter snowpack, snow-melt filter residues and top-soil samples were determined along three transects through industrial towns in the Usa basin, North-East Russia: Inta, Usinsk and Vorkuta. Snow was analysed for Ag, Al, As, Ba, Cd, Co, Cr, Cu, Mn, Ni, Pb, Sr and Zn using ICP-MS (Ca and K by F-AAS for Vorkuta only), pH and acidity/alkalinity. Filter residues were analysed for: Al, Ba, Ca, Cd, Cu, K, Mg, Mn, Ni, Pb, Sr and Zn using F-AAS and GF-AAS; top-soil samples were analysed for Ba, Cu, Mg, Mn, Na, Ni, Pb, Sr, Zn using F-AAS. Results indicate elevated concentrations of elements associated with alkaline combustion ash around the coal mining towns of Vorkuta and Inta. There is little evidence of deposition around the gas and oil town of Usinsk. Atmospheric deposition in the vicinity of Vorkuta, and to a lesser extent Inta, added significantly to the soil contaminant loading as a result of ash fallout. Acid deposition was associated with pristine areas whereas alkaline combustion ash near to emission sources more than compensated for the acidity caused by SO2.     

Combined glassification of EAF dust and incinerator fly ash

Stainless steelmaking dust contains large amount of heavy metals, such as Cr and Ni. If these hazardous materials are not treated properly, they will cause detrimental secondary contamination. Preliminary study on recycling stainless steelmaking dust employed the thermal molten technology. Glass-ceramics were formed by combination stainless steel dust and incinerator fly ash with the ratio of 1:9. The major phases were Augite, Akermanite, and Donathite. It was found that the glass-ceramics shows the best characteristic at 900 degrees C after 5 h of heat treatment. This product can be used as building materials or refractory materials.     

AFLP analysis as biomarker of exposure to organic and inorganic genotoxic substances in plants

In recent years several plant species have been in use as bioindicators and several tests have been developed to evaluate the toxicity of environmental pollutants in vegetal organisms. In the present paper Arabidopsis thaliana (L.) Heynh. (ecotype Wassilewskija) was used as bioindicators of two genotoxic substances: potassium dichromate and dihydrophenanthrene. Inhibition of seed germination was observed with both pollutants. AFLP analysis (i) indicated that both substances are genotoxic, (ii) showed that dihydrophenanthrene induces DNA changes in different target sequences than potassium dichromate, (iii) quantified the genotoxic effect using cluster analysis by comparing DNA from treated plants with that of control plants. On the basis of these considerations we suggest that AFLP method is a powerful tool for measuring qualitative and quantitative genotoxic activity due to environmental pollutants. AFLP method can be applied to a wide range of bioindicator organisms and may become a universal methodology to identify target genes for specific genotoxic agents. This could open up possibilities for designing specifically targeted assays and new approaches to risk assessment.     

Negative effects of humic acid addition on phytoremediation of pyrene-contaminated sediments by mangrove seedlings

Vegetated (with Kandelia candel seedlings) and non-vegetated mangrove microcosms were employed to remove pyrene from contaminated sediments, and the effects of adding 6.7% humic acid (HA) on such removal were investigated. At the end of 6-month treatment, residual pyrene concentrations in surface sediments (0-2 cm) of the contaminated microcosms reduced from an initial 5.82 to 0.63 microg g(-1) dw, and the reduction was less in HA amended microcosms with the residual pyrene concentration remained at 3.12 microg g(-1) dw. The pyrene removal percentages in microcosms with HA amendment were 29% for surface aerobic sediments and 41% for bottom (anaerobic) sediments, while the respective removal percentages in microcosms without HA amendment were 89% (surface sediments) and 53% (bottom sediments). Microcosms planted with K. candel seedlings had a significantly higher pyrene removal when compared to the non-vegetated ones, and the average removal percentages were 70.9% and 61.4%, respectively. However, when humic acid was added, no significant difference was found between vegetated and non-vegetated microcosms in pyrene removal, both had less than 40% removal, probably because plant growth in humic acid amended contaminated microcosms, in terms of total biomass, was reduced by 50%. Roots of K. candel could accumulate pyrene from contaminated microcosms, and pyrene concentrations in roots harvested from microcosms with and without humic acid addition were 6.01 and 3.46 microg g(-1) dw, respectively. These results suggest that the addition of HA to contaminated sediments decreased the mangrove microcosm's ability to remove pyrene as pyrene was more tightly bound to the organic matter and plant growth was reduced.     

Removal of heavy metals from a metaliferous water solution by Typha latifolia plants and sewage sludge compost

Typha latifolia plants, commonly known as cattails, were grown in a mixture of mature sewage sludge compost, commercial compost and perlite (2:1:1 by volume). Four Groups (A, B, C and D) were irrigated (once every two weeks) with a solution containing different concentrations of Cu, Ni, and Zn, where in the fifth (group M) tap water was used. At the end of the 10 weeks experimental period substrate and plants were dried, weighed and analysed for heavy metals. The amounts of all three metals removed from the irrigation solution, were substantial. In the roots and leaves/stems of T. latifolia the mean concentration of Zn reached values of 391.7 and 60.8 mg/kg of dry weight (d.w.), respectively. In the substrate of Group D all three metals recorded their highest mean concentrations of 1156.7 mg/kg d.w. for Cu, 296.7 mg/kg d.w. for Ni and 1231.7 mg/kg d.w. for Zn. Linear correlation analyses suggested that there was a linear relationship between the concentration of metals in the solutions and the concentration of metals in the substrates at the end of the experiment. The percentage removal of the metals in the substrate was large, reaching 100% for Cu and Zn in some groups and almost 96% for Ni in group D. The total amount of metals removed by the plants was considerably smaller than that of the substrate, due mainly to the small biomass development. A single factor ANOVA test (5% level) indicated that the build up in the concentration of metals in the roots and the leaves/stems was due to the use of metaliferous water solution and not from the metals pre-existing in the substrate. The contribution of the plants (both roots and leaves/stems) in the removing ability of the system was less than 1%.     

Study of metabolites from the degradation of polycyclic aromatic hydrocarbons (PAHs) by bacterial consortium enriched from mangrove sediments

The PAH metabolites produced during degradation of fluorene, phenanthrene and pyrene by a bacterial consortium enriched from mangrove sediments were analyzed using the on-fiber silylation solid-phase microextraction (SPME) combining with gas chromatography–mass spectrometry (GC–MS) method. Seventeen metabolites at trace levels were identified in different PAH degradation cultures based on the full scan mass spectra. In fluorene degradation cultures, 1-, 2-, 3- and 9-hydroxyfluorene, fluorenone, and phthalic acid were detected. In phenanthrene and pyrene degradation cultures, various common metabolites such as phenanthrene and pyrene dihydrodiols, mono-hydroxy phenanthrene, dihydroxy pyrene, lactone and 4-hydroxyphenanthrene, methyl ester, and phthalic acid were found. The detection of various common and novel metabolites demonstrates that SPME combining with GC–MS is a quick and convenient method for identification as well as monitoring the real time changes of metabolite concentrations throughout the degradation processes. The knowledge of PAH metabolic pathways and kinetics within indigenous bacterial consortium enriched from mangrove sediments contributes to enhance the bioremediation efficiency of PAH in real environment.     

Estrogenicity and acute toxicity of selected anilines using a recombinant yeast assay

Suspected estrogen modulators include industrial organic chemicals (i.e., xenoestrogens), and have been shown to consist of alkylphenols, bisphenols, biphenylols, and some hydroxy-substituted polycyclic aromatic hydrocarbons. The most prominent structural feature identified to be important for estrogenic activity is a polar group capable of donating hydrogen bonds (i.e., hydroxyl) on an aromatic system. The present study was undertaken to explore the estrogenic activity and acute toxicity of chemicals containing a weaker hydrogen bond donor group on aromatic systems, i.e., the amino substituent. There is a great deal of chemical similarity between aromatic amines (anilines) and aromatic alcohols (phenols). The chemicals chosen for the current study contained an amino-substituted benzene ring with hydrophobic constituents varying in size and shape. Thus, 37 substituted aromatic amines were assayed for estrogenic activity EC50 and acute toxicity LC50 using the Saccharomyces cerevisiae recombinant yeast assay. While the EC50 of 17-beta-estradiol occurs at the 10(-10) range, the aniline with the greatest activity had an EC50 of 10(-6) M. Thus, anilines, in general, are capable only of very weak estrogenic activity in this assay. A comparison of estrogenic potency between the present group of anilines and a set of previously tested analogous phenols indicated that anilines are consistently less estrogenic than phenols. A comparison of hazard indices (EC50/LC50) of these chemicals revealed that, for the vast majority of anilines, the EC50 and LC50 were in the same order of magnitude. More specifically, estrogenic activity of para-substituted alkylanilines increases with alkyl group size up to 5 carbons in length, after which the acute toxicity of the larger alkyl-substituents precluded the ability of the compound to induce the estrogenic response.