Glutathione S-transferase (GST) and peroxidase (POX) activities have a direct relation to the effect of stress on plant metabolism. Changes in the activities of the enzymes were therefore studied. Horseradish hairy roots were treated by selected bivalent ions of heavy metals (HMs) and nitroaromatic compounds (NACs). We have shown differences in GST activity when assayed with substrates 1-chloro-2,4-dinitrobenzene (CDNB) and 1,2-dichloro-4-nitrobenzene (DCNB). The conjugation of DCNB catalysed by GST was inhibited in all roots treated with HMs as compared to non-treated roots, whereas NACs caused induction of the activity in dependence on the exposition time and concentration of compounds. The conjugation of CDNB by GST was not affected to the same extent. The increase of GST activity was determined in cultures treated by nickel (0.1 mM) and diaminonitrotoluenes (DANTs, 0.1 mM) for 6 h, whereas the roots treated by 2,4,6-trinitrotoluene (TNT), 4-amino-2,6-dinitrotoluene (ADNT) and dinitrotoluene (DNT, 1.0 mM) needed 27 h treatment to induce the activity. The POX activity of cultures treated by HMs was inhibited to 17-35% in comparison to non-treated cultures. The POX activity of roots treated by TNT (0.1 and 1.0 mM) for 6 and 27 h and by ADNT (0.1 and 1.0 mM) for 6 h was inhibited. A partial increase of POX activity was measured in roots treated by all NACs for 27 h. The content of oxidized glutathione (GSSG) and reduced glutathione (GSH) in the roots differed significantly. It was followed as a symptom of the stress reaction of the plant metabolism to the effect of NACs and HMs. 相似文献
Municipal sewage is the main exposure route for antibiotics that are used in human medical care. Antibiotics that adsorb to the primary sludge and/or sur-plus activated sludge will enter the anaerobic digesters of municipal sewage treatment plants. Here anaerobic biodegradation or inhibition of anaerobic bacteria resulting in a disturbance of the process might occur. ISO standards 13641 (2003) and 11734 (1999) were used for assessing the anaerobic inhibition of 16 and the anaerobic biodegradability of 9 antibiotics respectively. Digestion sludge from a municipal sewage treatment plant (1g/l d.s.) was used as inoculum in both tests. In ISO 13641 (2003) most antibiotics showed only moderate inhibition effects after a 7 day incubation period, with EC50 values between 24 mg/l and more than 1000 mg/l (equal to mg/g d.s.). In contrast, metronidazol was decisively toxic to anaerobic bacteria with an EC50 of 0.7 mg/l. In the anaerobic degradation tests according to ISO standard 11734 (1995), only benzylpenicillin showed certain ultimate biodegradation after 60 days and most antibiotics inhibited the digesting sludge in the respective parallel tested inhibition controls. Thus the inhibition of anaerobic bacteria by antibiotics observed in the degradation tests was higher than expected from the results of the inhibition tests. The possible explanations are that distinct substrates are used (yeast extract versus sodium benzoate), that the digestion sludge loses activity during the washing steps performed for the degradation tests and that the exposure time in the degradation tests was 8 times longer than in the inhibition test. 相似文献
Soils can be contaminated by pharmaceuticals. The aim of this study was to evaluate the impact of soil conditions (influencing sorption and persistence of pharmaceuticals in soils) and plant type on the root uptake of selected pharmaceuticals and their transformation in plant-soil systems. Four plants (lamb’s lettuce, spinach, arugula, radish) planted in 3 soils were irrigated for 20 days (26) with water contaminated by one of 3 pharmaceuticals (carbamazepine, atenolol, sulfamethoxazole) or their mixture. The concentrations of pharmaceuticals and their metabolites in soils and plant tissues were evaluated after the harvest. Sulfamethoxazole and atenolol dissipated rapidly from soils. The larger concentrations of both compounds and an atenolol metabolite were found in roots than in leaves. Sulfamethoxazole metabolites were below the limits of quantifications. Carbamazepine was stable in soils, easily uptaken, accumulated, and metabolized in plant leaves. The efficiency of radish and arugula (both family Brassicaceae) in metabolizing was very low contrary to the high and moderate efficiencies of lamb’s lettuce and spinach, respectively. Compounds’ transformations mostly masked the soil impact on their accumulation in plant tissues. The negative relationships were found between the carbamazepine sorption coefficients and its concentrations in roots of radish, lamb’s lettuce, and spinach.
A model formulation based on "aquivalence", as defined in terms of activity is presented to estimate the multimedia fate of ionizing chemicals. The aquivalence approach is analogous to fugacity but aquivalence is applicable to neutral and ionizing compounds, and has been applied previously to speciating chemicals, notably metals. The new aquivalence-based mass-balance model treats ionizing organic compounds that exist as interconverting neutral and ionic species which are subject to fate processes at differing rates. The model is illustrated by application to four ionizing pharmaceuticals in Hamilton Harbour, Lake Ontario. At the system pH of 7.9-8.5, ibuprofen, gemfibrozil, and naproxen are expected to be almost entirely ionic and triclosan split between ionic and neutral forms. Measured seasonal surface water concentrations, which were 2-10 times lower in the late summer and fall than during spring, were used to solve for unknown values of chemical half-life in the water column due to degradation (photo- and bio-) of the ionizing and neutral forms and secondarily, ionic sorption coefficients of the ionizing forms. Model estimates of half-lives in the habour's water ranged from 11 to 77, 11 to 147 and 10 to 37 for ionic ibuprofen, gemfibrozil, and naproxen, respectively; and 4-22 days and 2-9 days for ionic and neutral triclosan, respectively, with the shortest half-lives in spring and the longest in summer. 相似文献
Heavy metals still represent a group of dangerous pollutants, to which close attention is paid. Many heavy metals are essential
as important constituents of pigments and enzymes, mainly zinc, nickel and copper. However, all metals, especially cadmium,
lead, mercury and copper, are toxic at high concentration because of disrupting enzyme functions, replacing essential metals
in pigments or producing reactive oxygen species. The toxicity of less common heavy metals and metalloids, such as thallium,
arsenic, chromium, antimony, selenium and bismuth, has been investigated. Here, we review the phytotoxicity of thallium, chromium,
antimony, selenium, bismuth, and other rare heavy metals and metalloids such as tellurium, germanium, gallium, scandium, gold,
platinum group metals (palladium, platinum and rhodium), technetium, tungsten, uranium, thorium, and rare earth elements yttrium
and lanthanum, and the 14 lanthanides cerium, dysprosium, erbium, europium, gadolinium, holmium, lutetium, neodymium, promethium,
praseodymium, samarium, terbium, thulium and ytterbium. 相似文献
The ability of plant species to accumulate arsenic (As) species in the biomass from As-contaminated soils is variable. Among the plants widely grown at the As-contaminated locations, Plantaginaceae and Cyperaceae families belong to the frequent ones. In this study, the ability of Plantago lanceolata (Plantaginaceae) and three wetland plant species representing the family Cyperaceae (Carex praecox, Carex vesicaria, and Scirpus sylvaticus) naturally occurring in the soils with an elevated As in the Czech Republic were investigated. The plants were cultivated under controlled conditions in an As-contaminated soil reaching 735?mg?kg?1 of the total As. The total As in plants reached up to 8.3?mg?kg?1 in leaves, and up to 155?mg?kg?1 in roots of C. praecox. Dominant As compounds were arsenite and arsenate with a small abundance of dimethylarsinic acid (DMA) in all the plant species. In Cyperaceae, small percentages of arsenobetaine (AB) and arsenocholine (AC) were detected, suggesting the ability of these plants to transform As into less toxic compounds. Moreover, the important role of As(V) sequestration on iron plaque on the root surface of Cyperaceae was confirmed. In this context, root washing with oxalic acid partially disrupted the iron plaque for the better release of arsenate. 相似文献
Biodegradation of poly(ε-caprolactone) composite with graphite oxide (GO) by the action of Bacillus subtilis (BS) was studied in this work. Nanocomposite produced in a form of thin film was exposed to nutrient cultivation medium with BS as well as to abiotic nutrient medium (control run) at 30 °C. The matrix itself was exposed to the same conditions for comparison. Biodegradation was demonstrated by the weight loss and the decrease of molecular weight during 21 days of the experiment as well as by changes in the surface morphology and structure. Both degraded and control materials were characterized by confocal laser scanning microscopy, differential scanning calorimetry, thermogravimetry, and Fourier transform infrared spectroscopy with attenuated total reflectance. The bacterial growth expressed as the measure of the optical density/turbidity in McFarland units and pH of medium were measured in situ during the experiment. Lipolytic activity of BS was determined by spectrophotometric assay. Degradation process was accompanied by the increase of matrix crystallinity degree. GO served as nucleating agent and facilitated absorption of cultivation media into the composite which led to the increase of the crystallinity degree also for control nanocomposite specimens. It was not evaluated to be promoter of biodegradation. The surface cracks formation was initiated by BS action. Large surface cracks were formed on BS-degraded composite surfaces while surface erosion was more significant on BS-degraded matrix. 相似文献
The biodegradation and elimination of antibiotics in municipal wastewater treatment plants is of particular concern because sewage is the main exposure route for antibiotics used in human medicine. The inherent biodegradability of 17 antibiotics was determined in a combined test design based on the Zahn-Wellens test (OECD 302 B, 1992) and the CO2-evolution test (OECD 301 B, 1992). CO2 Evolution test (Modified Sturm test). OECD Guideline for the Testing of Chemicals, Paris). Only benzylpenicillin sodium salt (Penicillin G) proved to be ultimately biodegradable, reaching ThCO2 degradation extents of 78-87%. Among the others, only amoxicillin, imipenem and nystatin showed certain ultimate biodegradation in few of the parallel flasks and can be regarded as partially biodegradable with formation of stable metabolites. The DOC-elimination of tetracycline-HCl showed a typical degradation curve starting with 18% and reaching the plateau phase at 80% after 21 days. Nevertheless, the CO2-evolution measured in parallel did not support the data, indicating that the time needed for reaching the adsorption equilibrium was underestimated. Several other antibiotics showed considerable DOC-elimination in the inherent test while only minor incidences of ultimate biodegradation were observed. The combination of CO2-evolution and DOC-elimination is a suitable instrument for assessing the behaviour of chemicals within one test. It enables one to assess both inherent ultimate biodegradability and DOC-elimination by sorption. The applicability of the test is limited to substances with a moderate toxicity. 相似文献
When soil structure varies in different soil types and the horizons of these soil types, it has a significant impact on water flow and contaminant transport in soils. This paper focuses on the effect of soil structure variations on the transport of pesticides in the soil above the water table. Transport of a pesticide (chlorotoluron) initially applied on soil columns taken from various horizons of three different soil types (Haplic Luvisol, Greyic Phaeozem and Haplic Cambisol) was studied using two scenarios of ponding infiltration. The highest infiltration rate and pesticide mobility were observed for the Bt1 horizon of Haplic Luvisol that exhibited a well-developed prismatic structure. The lowest infiltration rate was measured for the Bw horizon of Haplic Cambisol, which had a poorly developed soil structure and a low fraction of large capillary pores and gravitational pores. Water infiltration rates were reduced during the experiments by a soil structure breakdown, swelling of clay and/or air entrapped in soil samples. The largest soil structure breakdown and infiltration decrease was observed for the Ap horizon of Haplic Luvisol due to the low aggregate stability of the initially well-aggregated soil. Single-porosity and dual-permeability (with matrix and macropore domains) flow models in HYDRUS-1D were used to estimate soil hydraulic parameters via numerical inversion using data from the first infiltration experiment. A fraction of the macropore domain in the dual-permeability model was estimated using the micro-morphological images. Final soil hydraulic parameters determined using the single-porosity and dual-permeability models were subsequently used to optimize solute transport parameters. To improve numerical inversion results, the two-site sorption model was also applied. Although structural changes observed during the experiment affected water flow and solute transport, the dual-permeability model together with the two-site sorption model proved to be able to approximate experimental data. 相似文献
Incubation and pot experiments using poplar (Populus nigra L. cv. Wolterson) were performed in order to evaluate the questionable efficiency of EDDS-enhanced phytoextraction of Cu from contaminated soils. Despite the promising conditions of the experiment (low contamination of soils with a single metal with a high affinity for EDDS, metal tolerant poplar species capable of producing high biomass yields, root colonization by mycorrhizal fungi), the phytoextraction efficiency was not sufficient. The EDDS concentrations used in this study (3 and 6 mmol kg−1) enhanced the mobility (up to a 100-fold increase) and plant uptake of Cu (up to a 65-fold increase). However, despite EDDS degradation and the competition of Fe and Al for the chelant, Cu leaching cannot be omitted during the process. Due to the low efficiency, further research should be focused on other environment-friendly methods of soil remediation. 相似文献