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Результаты 181-190 из 2,512
The impact of in vivo and in vitro exposure to base analogue 5-FU on the level of DNA damage in haemocytes of freshwater mussels Unio pictorum and Unio tumidus Полный текст
2014
Gačić, Zoran | Kolarević, Stoimir | Sunjog, Karolina | Kračun-Kolarević, Margareta | Paunović, Momir | Knežević-Vukčević, Jelena | Vuković-Gačić, Branka
The impact of in vivo and in vitro exposure to anticancer drug 5-Fluorouracil (5-FU) on the level of DNA damage was evaluated using comet assay on haemocytes of freshwater mussels Unio pictorum and Unio tumidus. For the in vivo experiment, the groups of 5 mussels per concentration were exposed for 72 h to 5-FU (0.04, 0.4, 4, 40 and 100 μM) with 0.4 μM being the lowest concentration to induce significant DNA damage. For the in vitro experiment, the primary cultures of haemocytes were treated with 0.04, 0.4, 4 and 40 μM 5-FU for 22 h and the treatment with CdCl2 was used as a positive control. In contrast to in vivo exposure, 5-FU did not induce significant increase of DNA damage in vitro, possibly because of the absence of haemocytes proliferation in primary cultures.
Показать больше [+] Меньше [-]Distribution, source, fate and bioaccumulation of methyl siloxanes in marine environment Полный текст
2014
Hong, Wen-Jun | Jia, Hongliang | Liu, Cheng | Zhang, Zifeng | Sun, Yeqing | Li, Yi-Fan
Studies have shown that some cyclic methyl siloxanes were identified as characterized of persistent, bioaccumulated, toxic, and potential to ecological harm. In this study, we determined methyl siloxanes in seawater, sediment and bottom fish samples collected from marine environment in Northeast China. The mean concentrations of total methyl siloxanes were 46.1 ± 27.2 ng/L, 12.4 ± 5.39 ng/g dry weight (dw) and 5.10 ± 1.34 wet weight (ww) in seawater, sediment and fish, respectively. Very strong and significant correlations (r = 0.94, p < 0.0001) were found in compositions of methyl siloxanes between seawater and sewage, indicating that sewage was the main source of methyl siloxanes in the marine area studied. It was found that the mean value of biota-sediment accumulation factor (BSAF) was.0.716 ± 0.456 for D4, 0.103 ± 0.0771 for D5, 1.06 ± 0.528 for D6 and 0.877 ± 0.530 for D7.
Показать больше [+] Меньше [-]Transport of perfluoroalkyl acids in a water-saturated sediment column investigated under near-natural conditions Полный текст
2014
Vierke, Lena | Möller, Axel | Klitzke, Sondra
The aim of this study was to gain an understanding of the transport of C4–10 perfluoroalkyl carboxylic acids (PFCAs) and C4,6,8 perfluoroalkyl sulfonic acids (PFSAs) in a water-saturated sediment column representing a riverbank filtration scenario under near-natural conditions. Short-chain PFCAs and PFSAs with up to six C-atoms showed complete tracer-like breakthrough. Longer chain ones were retarded due to sorption to the sediment or due to other processes in the aqueous phase. The study reports the first column derived sediment–water partition coefficients ranging from 0.01 cm3 g−1 to 0.41 cm3 g−1 for C4,6 PFSAs and from 0.0 cm3 g−1 to 6.5 cm3 g−1 for C4,5,6,8,9 PFCAs. The results clearly indicate that short-chain PFCAs and PFSAs may pose a problem if contaminated surface waters are used for drinking water production via riverbank filtration.
Показать больше [+] Меньше [-]Modification of metal bioaccumulation and toxicity in Daphnia magna by titanium dioxide nanoparticles Полный текст
2014
Tan, Cheng | Wang, Wen-Xiong
Titanium dioxide (TiO2) nanoparticles are widely used in water treatments, yet their influences on other contaminants in the water are not well studied. In this study, the aqueous uptake, assimilation efficiency, and toxicity of two ionic metals (cadmium-Cd, and zinc-Zn) in a freshwater zooplankton, Daphnia magna, were investigated following 2 days pre-exposure to nano-TiO2. Pre-exposure to 1 mg/L nano-TiO2 resulted in a significant increase in Cd and Zn uptake from the dissolved phase. After the nano-TiO2 in the guts were cleared, the uptake rates immediately recovered to the normal levels. Concurrent measurements of reactive oxygen species (ROS) and metallothioneins (MTs) suggested that the increased metal uptake was mainly due to the increased number of binding sites provided by nano-TiO2 presented in the guts. Consistently, pre-exposure to nano-TiO2 increased the toxicity of aqueous Cd and Zn due to enhanced uptake. Our study provides the evidence that nano-TiO2 in the guts of animals could increase the uptake and toxicity of other contaminants.
Показать больше [+] Меньше [-]Reduced climate sensitivity of carbon, oxygen and hydrogen stable isotope ratios in tree-ring cellulose of silver fir (Abies alba Mill.) influenced by background SO2 in Franconia (Germany, Central Europe) Полный текст
2014
Boettger, Tatjana | Haupt, Marika | Friedrich, Michael | Waterhouse, John S.
The climate sensitivity of carbon (δ13C), oxygen (δ18O) and hydrogen (δ2H) isotope signatures in tree-ring cellulose of Abies alba Mill. from a marginally industrialized area of Franconia (Germany) was analysed for the last 130 years. All isotopes preserve climatic signals up to c. 1950 AD. After 1950 we observe a clear reduction in climate sensitivity of δ13C and δ2H while δ18O – climate relations remain well pronounced. Nevertheless statistical tests implied that SO2 background emissions of West Germany had influenced isotope signatures long before 1950. The relationships between isotope values and concentrations of SO2, dust, O3 and NO2 at the regional level during the period 1979–2006 indicate that δ13C and δ18O were influenced primarily by SO2. The impact of SO2 on δ2H was negligible, but the observed reduction of climate sensitivity may be caused by synergic influences. The results have significant implications if isotope signatures from tree-rings from anthropogenic influenced regions are used to reconstruct past climate.
Показать больше [+] Меньше [-]Plastic ingestion by Flesh-footed Shearwaters (Puffinus carneipes): Implications for fledgling body condition and the accumulation of plastic-derived chemicals Полный текст
2014
Lavers, Jennifer L. | Bond, Alexander L. | Hutton, Ian
To provide much needed quantitative data on the lethal and sublethal effects of plastic pollution on marine wildlife, we sampled breast feathers and stomach contents from Flesh-footed Shearwater (Puffinus carneipes) fledglings in eastern Australia. Birds with high levels of ingested plastic exhibited reduced body condition and increased contaminant load (p < 0.05). More than 60% of fledglings exceed international targets for plastic ingestion by seabirds, with 16% of fledglings failing these targets after a single feeding (range: 0.13–3.21 g of plastic/feeding). As top predators, seabirds are considered sentinels of the marine environment. The amount of plastic ingested and corresponding damage to Flesh-footed Shearwater fledglings is the highest reported for any marine vertebrate, suggesting the condition of the Australian marine environment is poor. These findings help explain the ongoing decline of this species and are worrying in light of increasing levels of plastic pollution in our oceans.
Показать больше [+] Меньше [-]Can Coronene and/or Benzo(a)pyrene/Coronene ratio act as unique markers for vehicle emission? Полный текст
2014
Shen, Guofeng | Chen, Yuanchen | Wei, Siye | Fu, Xiaofang | Ding, Aijun | Wu, Haisuo | Tao, Shu
Coronene is a high molecular weight polycyclic aromatic hydrocarbon with seven aromatic rings. It, more specifically a lower ratio of Benzo[a]pyrene to Coronone (BaP/COR), is suggested as a marker for vehicle emission. In the present study, emissions of Coronene were measured from residential combustions of wood, crop straw, and pellets. The detection of COR in non-vehicle emission sources, and comparable BaP/COR ratios between the solid fuel combustion and vehicle emissions indicated that the generality of COR or the BaP/COR ratio as markers for the vehicle emission would be questionable, especially for the area where solid fuel combustion dominated the PAHs emission.
Показать больше [+] Меньше [-]Ozone phytotoxic potential with regard to fragments of the Atlantic Semi-deciduous Forest downwind of Sao Paulo, Brazil Полный текст
2014
In the Metropolitan Region of Campinas (MRC), Brazil, high levels of primary pollutants contribute to ozone (O3) formation. However, little is known regarding the O3 effects in the tropics. Objectives in this study were to characterize the present levels of O3 pollution and to evaluate the relevance of current concentration-based indices for assessing the phytotoxic potential of O3. Changes in O3 concentrations and precursors at 5 monitoring stations within towns of MRC were analyzed. The daily O3 profile was typical for urban sites and showed little yearly variation. Given the permanently foliated forest canopy, yearly rather than seasonal O3 indices were thus more appropriate for estimating the effective ozone dose. With yearly SUM00, SUM60 and AOT40 of 156, 16 and 14 ppm h and confirmed by evidence of O3 injury in foliage, oxidative stress in the MRC has reached levels high enough to affect trees from the Atlantic Semi-deciduous Forest.
Показать больше [+] Меньше [-]Tetrabromobisphenol A and hexabromocyclododecane flame retardants in infant–mother paired serum samples, and their relationships with thyroid hormones and environmental factors Полный текст
2014
Kim, Ŭn-jung | Oh, Jeong-Eun
The concentrations of tetrabromobisphenol A (TBBPA) and hexabromocyclododecanes (HBCDs), and their correlations with thyroid hormones, were investigated in sera from 26 infants with congenital hypothyroidism, 12 healthy infants, and their mothers. The analyte concentrations were not significantly different in the two infant groups. Polybrominated diphenyl ethers (measured in a previous study) were the dominant brominated flame retardants, contributing 42–87% of the total, and HBCDs contributed 5–18%. TBBPA concentrations were 2–5 times higher in the infants than in the mothers. The TBBPA concentrations decreased dramatically with age for 2–3 months after birth, which might be caused by its relatively high maternal transfer rate, short half-life, and fast excretion. Significant correlations were found between mothers and infants in the TBBPA and HBCD concentrations, implying that maternal transfer was important. TBBPA correlated weakly with thyroid hormones, showing a positive relationship with FT4 but a negative relationship with T3.
Показать больше [+] Меньше [-]Phenanthrene binding by humic acid–protein complexes as studied by passive dosing technique Полный текст
2014
Zhao, Jian | Wang, Zhenyu | Ghosh, Saikat | Xing, Baoshan
This work investigated the binding behavior of phenanthrene by humic acids (HA-2 and HA-5), proteins (bovine serum albumin (BSA)), lysozyme and pepsin), and their complexes using a passive dosing technique. All sorption isotherms were fitted well with Freundlich model and the binding capability followed an order of HA-5 > HA-2 > BSA > pepsin > lysozyme. In NaCl solution, phenanthrene binding to HA-BSA complexes was much higher than the sum of binding to individual HA and BSA, while there was no enhancement for HA-pepsin. Positively charged lysozyme slightly lowered phenanthrene binding on both HAs due to strong aggregation of HA-lysozyme complexes, leading to reduction in the number of binding sites. The binding enhancement by HA-BSA was observed under all tested ion species and ionic strengths. This enhancement can be explained by unfolding of protein, reduction of aggregate size and formation of HA-BSA complexes with favorable conformations for binding phenanthrene.
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