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Iron ions can be used to degrade tetracycline dispersed in nature. Studies of absorption and fluorescence spectra and quantum chemistry calculations showed that iron is more readily released from Fe(III)-citrate than from Fe(III)-EDTA, so Fe(III)-citrate (Fe(III)-Cit) is more suitable for tetracycline (TC) degradation. At 30 °C, a severe degradation of TC by Fe(III)-Cit occurred as early as after 3 days of incubation in the light, and after 5 days in the dark. In contrast, the degradation of TC by Fe(III)-EDTA proceeded very slowly in the dark. By the fifth day of incubation of TC with Fe(III)-Cit in darkness, the concentrations of the former compound dropped by 55% and 75%, at 20 °C and 30 °C, respectively. The decrease in tetracycline concentrations caused by Fe(III)-EDTA in darkness at the same temperatures was only 2% and 6%, respectively. Light increased the degradation rates of TC by Fe(III)-EDTA to 20% and 56% at 20 °C and 30 °C, respectively. The key role of the light in the degradation of tetracycline by Fe(III)-EDTA was thus demonstrated. The TC degradation reaction showed a second-order kinetics. The rate constants of Fe(III)-Cit-induced TC degradation at 20 °C and 30 °C in darkness were k = 4238 M−1day−1 and k = 11,330 M−1day−1, respectively, while for Fe(III)-EDTA were 55 M−1day−1 and 226 M−1day−1. In light, these constants were k = 15,440 M−1day−1 and k = 40,270 M−1day−1 for Fe(III)-Cit and k = 1012 M−1day−1 and 2050 M−1day−1 at 20 °C and 30 °C; respectively. A possible reason for the higher TC degradation rate caused by Fe(III)-Cit can be the result of its lower thermodynamical stability compared with Fe(III)-EDTA, which we confirmed with our quantum chemistry calculations. Two quantum chemistry calculations showed that the iron complex with EDTA is more stable (the free energy of the ensemble is 15.8 kcal/mol lower) than the iron complex with Cit; hence, Fe release from Fe(III)-EDTA is less effective. [ABSTRACT FROM AUTHOR]

The phytotoxic effects of fluoride and its derivatives on the seeds and seedlings of the Colobanthus apetalus and Colobanthus quitensis were studied. This is a first study to evaluate the influence of sodium fluoride (NaF) on the morphophysiological and biochemical processes on two Colobanthus species. The influence of various concentrations of NaF (9 mM, 19 mM, 29 mM) on the germination capacity and germination rate of seeds, seedlings growth and the proline content of plant tissues was analyzed under laboratory conditions (20/10°C, 12/12 h). The seeds of C. apetalus were collected from a greenhouse, whereas the seeds of C. quitensis were collected in Antarctica and in a greenhouse (Olsztyn, Poland). The tested concentrations of NaF did not suppress the germination of C. apetalus seeds, but the germination of C. quitensis seeds was inhibited. Sodium fluoride mainly inhibited root growth of C. apetalus and C. quitensis. In both analyzed species, the free proline content of seedlings increased significantly under exposure to NaF. The results of this study clearly indicate that C. apetalus and C. quitensis are highly resistant to NaF stress. [ABSTRACT FROM AUTHOR]

The effect of methanesulfonic acid (MSA) on the morphophysiology and biochemistry of the subantarctic species Colobanthus apetalus and the Antarctic species Colobanthus quitensis was examined. We evaluated the effects of various concentrations of MSA on the germination capacity and germination rate of seeds, seedling growth, chlorophyll fluorescence in cotyledons, and the proline content of seedlings under laboratory conditions at temperatures of 20°C (day) and 10°C (night) with a 12/12 h photoperiod. The examined C. apetalus seeds were grown in a greenhouse, and C. quitensis seeds were harvested in Antarctica and grown in a greenhouse (Olsztyn, Poland). The seeds of C. apetalus were characterized by the highest germination capacity and the highest germination rate, whereas C. quitensis seedlings were characterized by the most favorable growth and development. Only the highest concentrations of MSA decreased the intensity of chlorophyll fluorescence in the cotyledons of both Colobanthus species. The proline content of C. apetalus and C. quitensis seedlings increased significantly after MSA treatments. The results of this study clearly indicated that Colobanthus quitensis is more resistant to chemical stress induced by MSA. This is a first study to investigate the influence of MSA on the morphophysiology and biochemistry of higher plants. [ABSTRACT FROM AUTHOR]

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Abstract: The structure and properties of polymer inclusion membranes for Pb(II) transport from solutions containing Pb(II), Ca(II), K(I) nitrates, and Na(I) acetate as a buffer were examined. The membranes were prepared from cellulose triacetate (support), dioctyl phthalate (plasticizer) and 2-(10-carboxydecylsulfanyl)benzoic acid methyl monoester as a new, Pb(II) selective ionophore (LSI). The effect of membrane composition upon transport rates was discussed in terms of percolation theory. The membrane structure was found inhomogeneous with a gradient-type distribution of the active phase (carrier and plasticizer). The presence of the overall transport limiting skin layer was confirmed by the application of scanning electron microscopy. The percolation parameters, i.e. critical volume fraction of the active phase ΦAP,c and the critical exponent τ, were found as equal to 0.62 and 1.11±0.07, respectively. However, the local parameters calculated for transport limiting layer were estimated as Φap,c equal to 0.10 and τ equal to 1.6±0.2. The following order of membrane selectivity was observed: Pb(II)≫K(I)≈Ca(II)≈Na(I) with the overall Pb(II) separation factors reaching the values up to 48,000 and Pb(II) fluxes up to 1.725×10−10 mol cm−2 s−1. The calculated percolation parameters suggest the porous structure of the attended membranes. The transport mechanism was found as limited by the diffusion processes. [Copyright &y& Elsevier]

Abstract: The properties of octylsulfanylacetic acid in pertraction of cations, especially lead(II), were investigated. Basic physico-chemical characteristics of the carrier, i.e., the dissociation constant K a and surface tension σ of its solution in 1,2-dichloroethane, were determined. A multimembrane hybrid system composed of a liquid membrane and two polymer cation-exchange membranes (Nafion-117) was used as the transport cell. The following order of selectivity was observed: Pb(II)≫Ca(II)≈K(I), with the separation factors α Ca Pb and α K Pb in the range of 4–45 and 6–47, respectively. The maximum output fluxes of lead(II) varied from 1.7 to 6.87·10−12 molcm2 s−1 depending on the carrier concentration (0.05–0.1moldm−3) in a liquid membrane. [Copyright &y& Elsevier]

Antibiotics represent a novel type of environment pollutants which modify chlorophyll content in plants. Spectroscopic methods were employed to investigate the effect of tetracycline on chlorophyll degradation. Changes in absorbance and fluorescence demonstrated that tetracycline reaction with chlorophyll results in the formation of pheophytin, which was confirmed by new bands typical of pheophytin which appeared in the absorbance spectrum. The rate of pheophytin formation depended on ratio tetracycline to chlorophyll concentration in solution. In solutions with chlorophyll concentration of C = 1 × 10−5 M and tetracycline concentrations of C = 1 × 10−3 M and C = 1 × 10−2 M, pheophytin was formed after 28 h and 25 min, respectively. The obtained lifetime for pheophytin formed during chlorophyll reaction - with tetracycline hydrochloride was τ = 5.71 ± 0.02 ns and its value coincides, within the error limits, with the value obtained for pure pheophytin purchased from ChromaDex. The experiment demonstrated two mechanisms of chlorophyll degradation to pheophytin by tetracycline hydrochloride, i.e. 1) loss of Mg2+ ions from the chlorophyll molecule as a result of the presence of H+ ions in solution (i.e. as a result of medium acidification), and 2) removal of Mg2+ ions directly from chlorophyll by tetracycline which binds Mg2+ ions from the chlorophyll. We demonstrated that magnesium occurring in low concentrations attached to a tetracycline molecule in the BCD ring, and that the second ion of Mg2+ may attach to the A ring of tetracycline at higher Mg2+ concentrations. Two fluorescence bands appeared which indicated such magnesium attachments indeed occurred. • Tetracycline degrades chlorophyll to pheophytin and magnesium knocked out from chlorophyll is attached to tetracycline. • Several chlorophyll degradation processes have been demonstrated in the presence of tetracycline. • Magnesium in low concentrations attaches to a tetracycline in the BCD ring, whereas in higher concentrations to the A ring. [ABSTRACT FROM AUTHOR]