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Результаты 691-700 из 4,241
PM2.5-bound metal metabolic distribution and coupled lipid abnormality at different developmental windows
2017
Ku, Tingting | Zhang, Yingying | Ji, Xiaotong | Li, Guangke | Sang, Nan
Atmospheric fine particulate matter (PM2.5) is a serious threat to human health. As a toxicant constituent, metal leads to significant health risks in a population, but exposure to PM2.5-bound metals and their biological impacts are not fully understood. In this study, we determined the metal contents of PM2.5 samples collected from a typical coal-burning city and then investigated the metabolic distributions of six metals (Zn, Pb, Mn, As, Cu, and Cd) following PM2.5 inhalation in mice in different developmental windows. The results indicate that fine particles were mainly deposited in the lung, but PM2.5-bound metals could reach and gather in secondary off-target tissues (the lung, liver, heart and brain) with a developmental window-dependent property. Furthermore, elevations in triglycerides and cholesterol levels in sensitive developmental windows (the young and elderly stages) occurred, and significant associations between metals (Pb, Cd, Mn, and As) and cholesterol in the heart, brain and liver were observed. These findings suggest that PM2.5 inhalation caused selective metal metabolic distribution in tissues with a developmental window-dependent property and that the effects were associated with lipid alterations. This provides a foundation for the underlying systemic toxicity following PM2.5 exposure based on metal components.
Показать больше [+] Меньше [-]The improvement of multi-contaminated sandy loam soil chemical and biological properties by the biochar, wood ash, and humic substances amendments
2017
Pukalchik, Maria | Mercl, Filip | Panova, Maria | Břendová, Kateřina | Terekhova, Vera A. | Tlustoš, Pavel
Nowadays trace metal contamination of soils represents an important environmental hazard. Nevertheless, the use of some secondary waste products as amendments may restore the common soil functions. This paper focuses on the chemical and biological influence of wood biochar (BC), wood ash (WA) and humic substances (HS), alone and in the mixtures, on a heavily multi-contaminated sandy loam soil. The soil was amended by above-mentioned materials to follow a pH-increasing design (pHCa from 6.0 to 6.5, 7.0 and 7.5); soil samples were analyzed after 3, 30, and 60 days using a set of variables, namely the plant-available trace element concentrations (Cu, Cd, and Zn), microbial biomass carbon (Cmic), and microbial quotient (qCO2), as well as toxicity to Sinapis alba and Daphnia magna. Wood ash and WA + HS were the most efficient treatments to decrease mobile Cd and Zn concentrations in the soil, while HS, BC, and BC + HS combinations were the most effective in reducing the Cu mobility. The effect of BC and WA on the Cmic and qCO2 was mostly negative, whereas adding HS markedly increased Cmic and reduced qCO2 in soil. After amendment applications, the root elongation of mustard was significantly increased in HS and combined treatments (BC + HS, WA + HS). Additionally, BC + HS, WA + HS and WA 8.4% significantly decreased the toxicity of leachates to D. magna to the low-, or non-toxic levels. Our results suggest that the combination of amendments with HS can be a suitable remediation strategy for heavily contaminated soils.
Показать больше [+] Меньше [-]Influence of graphene oxide on the transport and deposition behaviors of colloids in saturated porous media
2017
Peng, Shengnan | Wu, Dan | Ge, Zhi | Tong, Meiping | Kim, Hyŏn-jŏng
The effects of graphene oxide (GO) on the transport and deposition behaviors of colloids with different sizes in packed quartz sand were investigated in both NaCl (10 and 50 mM) and CaCl2 solutions (1 and 5 mM) at pH 6. Fluorescent carboxylate-modified polystyrene latex microspheres (CMLs) with size ranging from 0.2 to 2 μm were utilized as model colloids. Both breakthrough curves and retained profiles of colloids in the presence and absence of GO in suspensions under all examined solution conditions were analyzed. The breakthrough curves of all three different-sized CMLs with GO were higher yet the retained profiles were lower than those without GO at both examined ionic strengths in NaCl solutions. The observation showed that GO increased the transport and decreased the deposition of all three different-sized CMLs in NaCl solutions. However, in CaCl2 solutions, opposite observation was achieved at two different ionic strength conditions. Specifically, the presence of GO increased the transport and decreased the deposition of all three different-sized CMLs in 1 mM CaCl2 solutions, whereas, it decreased the transport and increased the deposition of all three different-sized CMLs in 5 mM CaCl2 solutions. Comparison the breakthrough curves and retained profiles of CMLs versus those of GO yielded that the overall transport and deposition behaviors of all three different-sized CMLs with GO copresent in suspensions agreed well with the transport and deposition behaviors of GO under all examined conditions. The transport and deposition behaviors of CMLs in packed porous media clearly were controlled by those of GO under the conditions investigated in present study due to the adsorption of CMLs onto GO surfaces. Our study showed that once released into natural environment, GO would adsorb (interact with) different types of colloids and thus have significant influence on the fate and transport of colloids in porous media.
Показать больше [+] Меньше [-]Microplastic ingestion in fish larvae in the western English Channel
2017
Steer, Madeleine | Cole, Matthew | Thompson, Richard C. | Lindeque, Penelope K.
Microplastics have been documented in marine environments worldwide, where they pose a potential risk to biota. Environmental interactions between microplastics and lower trophic organisms are poorly understood. Coastal shelf seas are rich in productivity but also experience high levels of microplastic pollution. In these habitats, fish have an important ecological and economic role. In their early life stages, planktonic fish larvae are vulnerable to pollution, environmental stress and predation. Here we assess the occurrence of microplastic ingestion in wild fish larvae. Fish larvae and water samples were taken across three sites (10, 19 and 35 km from shore) in the western English Channel from April to June 2016. We identified 2.9% of fish larvae (n = 347) had ingested microplastics, of which 66% were blue fibres; ingested microfibers closely resembled those identified within water samples. With distance from the coast, larval fish density increased significantly (P < 0.05), while waterborne microplastic concentrations (P < 0.01) and incidence of ingestion decreased. This study provides baseline ecological data illustrating the correlation between waterborne microplastics and the incidence of ingestion in fish larvae.
Показать больше [+] Меньше [-]Where do uncertainties reside within environmental risk assessments? Testing UnISERA, a guide for uncertainty assessment
2017
Skinner, Daniel J.C. | Rocks, Sophie A. | Pollard, Simon J.T.
A means for identifying and prioritising the treatment of uncertainty (UnISERA) in environmental risk assessments (ERAs) is tested, using three risk domains where ERA is an established requirement and one in which ERA practice is emerging. UnISERA's development draws on 19 expert elicitations across genetically modified higher plants, particulate matter, and agricultural pesticide release and is stress tested here for engineered nanomaterials (ENM). We are concerned with the severity of uncertainty; its nature; and its location across four accepted stages of ERAs. Using an established uncertainty scale, the risk characterisation stage of ERA harbours the highest severity level of uncertainty, associated with estimating, aggregating and evaluating expressions of risk. Combined epistemic and aleatory uncertainty is the dominant nature of uncertainty. The dominant location of uncertainty is associated with data in problem formulation, exposure assessment and effects assessment. Testing UnISERA produced agreements of 55%, 90%, and 80% for the severity level, nature and location dimensions of uncertainty between the combined case studies and the ENM stress test. UnISERA enables environmental risk analysts to prioritise risk assessment phases, groups of tasks, or individual ERA tasks and it can direct them towards established methods for uncertainty treatment.
Показать больше [+] Меньше [-]A novel XRF method to measure environmental release of copper and zinc from antifouling paints
2017
Ytreberg, Erik | Lagerström, Maria | Holmqvist, Albin | Eklund, Britta | Elwing, Hans | Dahlström, Magnus | Dahl, Peter | Dahlström, Mia
The release of copper (Cu) and zinc (Zn) from vessels and leisure crafts coated with antifouling paints can pose a threat to water quality in semi-enclosed areas such as harbors and marinas as well as to coastal archipelagos. However, no reliable, practical and low-cost method exists to measure the direct release of metals from antifouling paints. Therefore, the paint industry and regulatory authorities are obliged to use release rate measurements derived from either mathematical models or from laboratory studies. To bridge this gap, we have developed a novel method using a handheld X-Ray Fluorescence spectrometer (XRF) to determine the cumulative release of Cu and Zn from antifouling paints. The results showed a strong linear relationship between XRF Kα net intensities and metal concentrations, as determined by ICP-MS. The release of Cu and Zn were determined for coated panels exposed in harbors located in the Baltic Sea and in Kattegat. The field study showed salinity to have a strong impact on the release of Cu, i.e. the release increased with salinity. Contrary, the effect of salinity on Zn was not as evident. As exemplified in this work, the XRF method also makes it possible to identify the governing parameters to the release of Cu and Zn, e.g. salinity and type of paint formulation. Thus, the XRF method can be used to measure environmentally relevant releases of metallic compounds to design more efficient and optimized antifouling coatings.
Показать больше [+] Меньше [-]The acute toxic effects of 1-alkyl-3-methylimidazolium nitrate ionic liquids on Chlorella vulgaris and Daphnia magna
2017
Zhang, Cheng | Zhang, Shuai | Zhu, Lusheng | Wang, Jinhua | Wang, Jun | Zhou, Tongtong
Given their increasingly widespread application, the toxic effects of ionic liquids (ILs) have become the subject of significant attention in recent years. Therefore, the present study assessed the acute toxic effects of 1-alkyl-3-methylimidazolium nitrate ([Cnmim]NO3 (n = 2, 4, 6, 8, 10, 12)) on Chlorella vulgaris and Daphnia magna. The sensitivity of the tested organism Daphnia magna and the investigated IL concentrations in water using high-performance liquid chromatography (HPLC) were also evaluated to demonstrate the reliability of the present study. The results illustrated that Daphnia magna is indeed sensitive to the reference toxicant and the investigated ILs were stable in the aquatic environment. The 50% effect concentration (EC50) was used to represent the acute toxic effects on Chlorella vulgaris and Daphnia magna. With the increasing alkyl-chain lengths, the toxicity of the investigated ILs increased in both the test organisms. Accordingly, the alkyl-chain lengths can cause significantly toxic effects on aquatic organisms, and Daphnia magna are much more sensitive than Chlorella vulgaris to the imidazolium-based ILs used in the present study. Furthermore, the present study provides more information on the acute toxic effects of 1-alkyl-3-methylimidazolium nitrate.
Показать больше [+] Меньше [-]Response of Rhizobium to Cd exposure: A volatile perspective
2017
Cardoso, Paulo | Santos, Magda | Freitas, Rosa | Rocha, Sílvia M. | Figueira, Etelvina
The volatile metabolome of Rhizobium sp. strain E20-8 exposed to three concentrations of cadmium (2.5, 5.0 and 7.5 μM) was screened using comprehensive two-dimensional gas chromatography coupled to time of flight mass spectrometry (GC × GC–ToFMS), combined with headspace solid phase microextraction (HS-SPME). Cd exposure induced a global increase in the concentration of volatile organic compounds (VOCs) both intra and extracellularly. Peak areas of several linear alkanes, ketones, aldehydes, alcohols, terpenic and volatile sulfur compounds, and one ester (ethyl acetate), were especially increased when compared with the control condition (no Cd). These compounds might originate from the metabolization of toxic membrane peroxidation products, the proteolysis of oxidized proteins or the alteration of metabolic pathways, resulting from the oxidative stress imposed by Cd. Several VOCs are related to oxidative damage, but the production of VOCs involved in antioxidant response (menthol, α-pinene, dimethyl sulfide, disulfide and trisulfide, 1-butanol and 2-butanone) and in cell aggregation (2,3-butanedione, 3-methyl-1-butanol and 2-butanone) is also observed. These results bring new information that highlights the role of VOCs on bacteria response to Cd stress, identify a novel set of biomarkers related with metal stress and provide information to be applied in biotechnological and remediation contexts.
Показать больше [+] Меньше [-]Community response to construction noise in three central cities of Zhejiang province, China
2017
Liu, Yong | Xia, Bo | Cui, Caiyun | Skitmore, R. M. (Ronald Martin)
As a common source of environmental noise in China and many developing countries worldwide, construction work provokes many complaints and deterioration in acoustic climate quality. This paper describes research to obtain an improved understanding of people's community response to, and evaluation of, construction noise in three central cities of Zhejiang province, China. This involved carrying out a social survey using standard questionnaires developed by the International Commission on Biological Effects of Noise (ICBEN). A dose-response relationship model is established using a quadratic polynomial regression analysis based on construction noise exposure measurements from 40 construction sites in Hangzhou, Ningbo and Wenzhou.The results of the study indicate that the majority of people have a negative attitude to construction noise; the noise ranges between 60 dB and 80 dB (compared with 50 dB–70 dB traffic noise in Tianjin), with the percentage of highly annoyed people affected increasing from 15%-20% to 30%–40% over the range. There also different levels of annoyance depending on the time of day, and the location and activities of those affected. Other cultural differences are also apparent both between Ningbo/Wenzhou and the more urbane citizens of Hangzhou, and the Chinese people and their more noise-tolerant EU and Vietnam counterparts.The findings of this study provide a new perspective for the study of construction noise that can help local governments have an improved understanding of how residents react to construction noise for the purpose of selecting construction noise-mitigation projects and introducing construction noise-control regulations.
Показать больше [+] Меньше [-]Degradation of 2,4,6-trichlorophenol with peroxymonosulfate catalyzed by soluble and supported iron porphyrins
2017
Günay, Tuğçe | Çimen, Yasemin
Degradation of 2,4,6-trichloropenol (TCP) with peroxymonosulfate (PMS) catalyzed by iron porphyrin tetrasulfonate ([FePTS)] was investigated in an 8-to-1 (v/v) CH3OH-H2O mixture. Typical reaction medium contained a 4.00 mL methanol solution of TCP (0.100 mmol), a 0.50 mL aqueous solution of catalyst (5.0 × 10⁻⁴ mmol), and 0.100 mmol PMS (as 0.031 g of Oxone). The reaction was performed at ambient temperature. The conversion of TCP was 74% in 30 min and 80% in 6 h when the catalyst was [FePTS]. Amberlite IRA-900 supported [FePTS] catalyst was also prepared. In the recycling experiments the homogeneous [FePTS] lost its activity after the first cycle, while [FePTS]-Amberlite IRA 900 maintained its activity for the first 2 cycles. After the second cycle, the conversion of TCP dropped to <10% for Amberlite IRA-900 supported [FePTS] catalyst. The degradation of TCP with PMS was also attempted using cobalt, copper, nickel and palladium porphyrin tetrasulfonate catalysts, however, no catalytic activity was observed with these structures.
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