Chloride concentration affects soil microbial community

We studied the effect of increased inorganic chloride concentration on forest soil microflora in a laboratory experiment. Microbial DNA extracted from experimental soil samples was amplified with PCR using primer pairs specifically amplifying bacterial, eukaryotic and fungal DNA fragments. The resulting amplified DNA was further used for terminal restriction fragment length polymorphism (TRFLP) analysis. Our work revealed that chloride concentration affects the indigenous microbial community in experimental soil. This was documented on an unidentified microorganism whose DNA was detectable in soil high in chloride but was not found in soil with low chloride concentration. The presence of the organism responsive to increased chloride concentration was associated with the highest observed value of chlorination of humic acid, suggesting possible role of this organism in soil chlorine turnover. High chloride concentration in the soil tended to decrease the rate of degradation of trichloroacetic acid. The problems connected with measurement of chlorination rates in soil are discussed.     

Synthesis of zirconia-immobilized copper chelates for catalytic decomposition of hydrogen peroxide and the oxidation of polycyclic aromatic hydrocarbons

Chelating sorbents with diethylenetriaminepenta(methylene-phosphonic acid) (DTPMPA) and ethylenediaminetetraacetic acid ligands immobilized on zirconia matrix were prepared and subsequently saturated with Cu(II). All the Cu chelates catalyzed decomposition of H(2)O(2) yielding highly reactive hydroxyl radicals. All of them were also able to catalyze degradation of polycyclic aromatic hydrocarbons (anthracene, benzo[a]pyrene and benzo[b]fluoranthene). The most effective DTPMPA-based catalysts G-32 and G-35 (10 mg ml(-1) with 100 mmol H(2)O(2)) caused almost complete decomposition of 15 ppm anthracene and benzo[a]pyrene during a five day catalytic cycle at 30 degrees C. Anthracene-1,4-dione was the main product of anthracene oxidation by all catalysts. The catalysts were active in several cycles without regeneration.     

Rhizosphere localized cationic peroxidase from barley roots is strongly activated by cadmium and correlated with root growth inhibition

The activity of Cd-induced POD isozyme isolated from the surface of intact barley roots growing under some abiotic stress conditions (toxic metals: Al, Co, Cu, Hg; drought, NaCl, extreme temperatures: heat, cold) and compounds activating (2,4-D) or inhibiting (SHAM) POD activity as well as H(2)O(2) and H(2)O(2) scavenger (DTT) was characterized. Strong Cd concentration-dependent accumulation of one cationic POD isozyme was observed on PAGE, which correlated with Cd- and other stress induced root growth inhibition. This isoPOD is basic with isoelectric point about 9 and its localization is restricted only to the apical part of the barley root tip.     

A new twist on an old regression: transfer of chemicals to beef and milk in human and ecological risk assessment

Exposure of humans to chemicals in beef or milk is part of almost all risk evaluation procedures carried out to reduce emissions or to remediate sites. Concentrations of substances in these livestock products are often estimated using log-log regressions that relate the biotransfer factor BTF to the octanol-water partition ratio K(ow). However, the correctness of these empirical correlations has been questioned. Here, we compare them to the mechanistic model OMEGA that describes the distribution of substances in organisms by integrating theory on chemical fugacity and biological allometry. OMEGA has been calibrated and validated on thousands of laboratory and field data, reflecting many chemical substances and biological species. Overall fluxes of water, food, tissue (growth), milk and stable substances calculated by OMEGA are within a factor of two from independent data obtained in experiments. Rate constants measured for elimination of individual compounds of a recalcitrant nature vary around the level expected from the model for output to faeces and milk. Both data and model suggest that biotransfer BTF of stable substances to beef and milk is independent of the octanol-water partition ratio K(ow) in the range of 10(3)-10(6). This contradicts empirical regressions including stable and labile compounds. As expected, levels of labile substances vary widely around a tentative indication derived from the model. Transformation and accumulation of labile substances remains highly specific for the chemical and organism concerned but depends weakly on the octanol-water partition ratio K(ow). Several possibilities for additional refinement are identified.     

Possible effects of persistent organochlorinated pollutants cocktail on thyroid hormone levels and pituitary-thyroid interrelations

In polluted district of Michalovce in East Slovakia (POLL) and two districts with background pollution (BCGR) 2046 adults (834 males and 1212 females aged 20-75 years) were examined. Serum levels of thyrotropin (TSH), free thyroxine (FT4), total triiodothyronine (TT3) and antithyroperoxidase antibodies (TPOab) were estimated by electrochemiluminiscent assay and also these of 15 polychlorinated biphenyl congeners (PCBs), p,p'-DDE, p,p'-DDT, hexachlorobenzene (HCB) and hexachlorocyclohexane were measured by high resolution gas chromatography/mass spectrometry. In addition, also dioxins, furans, coplanar- and mono-ortho-PCBs as well as selected hydroxylated and methylsulphonated PCBs and DDE metabolites were measured by appropriate methods based on gas chromatography/mass spectrometry principle. In POLL significantly higher levels of all organochlorines were found than these in BCGR. When pooled values from both areas were stratified in terms of PCBs level and treated as continuous variables, positive association of PCBs with FT4 and TT3 was found, the latter two being also mutually associated. However, within the category of PCBs level <530 ng/glipid (n=232) the association between PCBs and both the FT4 (p<0.09) and TT3 (p<0.03) was negative and any association of these was not found within the category of PCBs level of 531-1000 ng/g (n=691). In contrast, in the category of 531-2000 ng/g (n=1307) positive association appeared between PCBs and FT4 (p<0.001) as well as TT3 (p<0.05). Highly significant association of PCBs with FT4 (p<0.001) was further found in the categories with PCBs level of 1001-101414 ng/g (n=1307) and 2001-101414 (n=1123), while significant association with TT3 was observed only in the category of 531-2000 ng/g. Such findings suggest possible threshold level in positive effect of PCBs on FT4 and TT3 level which seems to be individual and located somewhere around the PCBs level of 1000 ng/g. However, highly significant negative association of both FT4 and TT3 with TSH was found in each of above indicated PCBs categories. Considerable difference in FT4 and TT3 level between large groups of subjects with the same range of PCBs level was also found suggesting different individual susceptibility to the effects of organochlorines. Among a total of 26 cases from POLL with very low TSH level (<0.5 mU l(-1)) 13 cases showed very high level of PCBs, FT4 and TT3, thus supporting a hypothesis on a novel sporadic form of high PCBs related peripheral subclinical hyperthyroidism possibly resulting from the long-term disruption of equilibrium between bound and free thyroxine in plasma by high PCBs level followed by a striking inhibition of TSH release from the pituitary.     

Brominated flame retardants and related chlorinated persistent organic pollutants in fish from river Elbe and its main tributary Vltava

Brominated flame retardants (BFRs) are widely used industrial chemicals, residues of which can be nowadays found in all environmental compartments. The widespread presence of BFRs in various environmental compartments and food chain is a consequence of both their broad application area and physico-chemical properties, such as resistance to degradation and high lipophilicity. Alike in the case of other halogenated persistent organic pollutants (POPs), fish can be used as a bioindicator of aquatic environment pollution. In presented study, conducted in the year 2005, altogether 80 samples representing the most abundant fresh water fish species, viz. chub (Leuciscus cephalus), bream (Abramis brama), and perch (Perca fluviatilis) collected in 11 sampling sites located at Elbe and Vltava (Moldau) rivers were examined for levels of major BFRs. Without any exception, BFRs were detected in all fish samples. BDE 47 was the dominating congener in all fish species. This fact was not surprising, since it used to be the main component in various kinds of technical mixtures. With regard to relatively high levels of BDE 47 in fish tissue, as compared to other BFRs, and considering strong correlation with the total PBDEs content, simplified laboratory examination and, consequently, increased samples throughput can be obtained when only this congener is monitored. The potential of comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GCxGC-TOFMS), to provide more comprehensive information on the bioaccumulating chemicals occurring in fish samples, has been demonstrated in this study.     

Characterization of humic substances of different origin by means of mass spectrometry and neural networks

Mass spectrometry fingerprinting of humic acids extracted from different soils has been carried out using laser desorption/ionization mass spectrometry (LDI-TOF MS). LDI-TOF MS provides characteristic mass spectra fingerprints for the humic acids of different origin. The information given in the fingerprints was evaluated for natural grouping trends in the samples by neural networks computing tools, such as self-organizing feature map (SOFM). This approach is efficient for recognizing patterns in the humic acids samples independently of their characteristic variability; variability characterizing natural products such as humic substances. The use of multi-layer perceptron artificial neural networks gave a successful classification of the samples.     

Electrochemical treatment of a simple azodye and analysis of the degradation products using high performance liquid chromatography-diode array detection-tandem mass spectrometry

The simple, low molecular weight, azodye acid yellow 9 (AY9) is electrochemically treated in a suitable electrolytic cell using NaCl as a supporting electrolyte, carbon fleece as cathode and platinated titanium as anode. Samples from certain time periods of treatment are analysed. HPLC-UV chromatograms demonstrate the degradation of the initial azodye, while diode array detector (DAD) spectra give evidence concerning the aromaticity of the degradation products and tandem mass spectrometry (MS(2)) offer structural information on some final products. In order to distinguish cathodic and anodic processes, separated cells connected with electrolytic junction are used, clarifying the oxidative and reductive decomposition pathways of the studied azodye. Several intermediate products are identified in very low concentrations such as hydrazo-derivatives, chlorinated aromatic and aliphatic compounds as well as amino- and hydroxyl-products. Experiments in separated electrolytic cells show that azodye degradation proceeds mainly oxidatively, since cathodic action is extremely limited, while treatment in common cells results in complete decoloration and presence of degradation products in very low concentration. Finally, simple degradation mechanisms are suggested based on tandem mass spectrometric identification of several degradation products.     

Spectroscopic and conformational properties of size-fractions separated from a lignite humic acid

A lignite humic acid (HA) was fractionated by preparative high performance size-exclusion chromatography (HPSEC) in seven different size-fractions. The size-fractions were characterized by cross polarization (CP) magic angle spinning (MAS) (13)C NMR spectroscopy and a further analytical HPSEC elution under UV and fluorescence detection. The alkyl hydrophobic components mainly distributed in the largest molecular-size-fraction, whereas the amount of oxidized carbons increased with decreasing size of fractions. Cross polarization time (T(CH)) and proton spin-lattice relaxation time in the rotating frame (T(1rho)(H)) were measured from variable contact time (VCT) experiments. The bulk HA was characterized by the shortest T(CH) values and the longest T(1rho)(H) values which suggested, respectively, one. an aggregation of components in a large conformation that favored a fast H-C cross polarization, and, two. consequent steric hindrances that prevented fast local molecular motions and decreased proton relaxation rates. Conversely, the separated size-fractions showed longer T(CH) values and shorter T(1rho)(H) values than the bulk HA, thereby indicating that they were constituted by a larger number of mobile molecular conformations. The UV and fluorescence absorptions were both low in the large size-fractions that mainly contained alkyl carbons, whereas they increased in the olephinic- and aromatic-rich fractions with intermediate molecular-size, and decreased again in the smaller fractions which were predominantly composed by oxidized carbons. These results support the supramolecular structure of humic substances and indicate that the observed variation in conformational distribution in humic association may be used to explain environmental processes with additional precision.