خيارات البحث
النتائج 771 - 780 من 4,895
Association of serum levels of 4-tertiary-octylphenol with cardiovascular risk factors and carotid intima-media thickness in adolescents and young adults
2019
Lin, Chien-Yu | Hwang, Yi-Ting | Chen, Pau-Chung | Sung, Fung-Chang | Su, Ta-Chen
In the family of alkylphenolic compounds, 4-tertiary-Octylphenol (4-t-OP) is extensively used in many products. In animal and in vitro studies, 4-t-OP exposure has been linked to cardiovascular disease (CVD) risk factors; however, there are no previous human epidemiological studies. In this study, 886 subjects were recruited from a cohort of Taiwanese adolescents and young adults to study the relationship between serum levels of 4-t-OP, CVD risk factors, and common carotid artery intima-media thickness (CIMT). The geometric mean (SD) 4-t-OP concentration was 32.52 (1.71) ng/mL. We found that serum levels of 4-t-OP were negatively associated with markers of glucose homeostasis (insulin, homeostasis model assessment of insulin resistance (HOMA-IR) and homeostasis model assessment of β-cell function (HOMA-β)), z score of body mass index (BMI z score) and CIMT but were positively associated with lipid profiles (high density lipoprotein cholesterol (HDL-C), Apolipoprotein A1). A one-unit elevation in natural log-transformed 4-t-OP (ng/mL) was negatively correlated with CIMT (mm) (β = −0.029, SE = 0.003, P < 0.001) in multiple linear regression analyses. The relationship between 4-t-OP and CIMT remained the same in all subgroups or if bisphenol A (BPA) was considered a covariate. In this study, we observed that higher levels of 4-t-OP levels were negatively correlated with markers of glucose homeostasis, BMI z score, and CIMT; positively correlated with lipid profiles (HDL-C and apolipoprotein A) in this cohort. Future research on exposure to 4-t-OP and CVD risk factors is warranted.
اظهر المزيد [+] اقل [-]Anaerobic ammonium oxidation in agricultural soils-synthesis and prospective
2019
Nie, San'an | Zhu, Gui-Bing | Singh, Brajesh | Zhu, Yong-Guan
Denitrification is considered as the dominant nitrogen (N) removing pathway, however, anaerobic oxidation of ammonium (anammox) also plays a significant part in N loss in agricultural ecosystems. Large N inputs into agricultural soils may stimulate the growth of anammox bacteria, resulting in high activity and diversity of anammox bacteria and subsequent more N loss. In some specific niches, like oxic-anoxic interface, three processes, nitrification, anammox and denitrification couple with each other, and significant anammox reaction could be observed. Soil parameters like pH, dissolved oxygen, salinity, oxidation-reduction potential (ORP), and substrate concentrations impact the anammox process. Here we summarize the current knowledge on anammox activity and contribution to N loss, abundance and diversity of anammox bacteria, factors affecting anammox, and the relationship between anammox and other N loss pathways in agricultural soils. We propose that more investigations are required for (1) the role of anammox to N loss with different agricultural management strategies; (2) microscale research on the coupling of nitrification-anammox-denitrification, that might be a very complex process but ideal model for further studies responsible for N cycling in terrestrial ecosystems; and (3) new methods to estimate differential contributions of anammox, codenitrification and denitrification in total N loss in agricultural ecosystems. New research will provide much needed information to quantify the contribution of anammox in N loss from soils at landscape, ecosystem and global scales.
اظهر المزيد [+] اقل [-]Relationships between Pb, As, Cr, and Cd in individual cows’ milk and milk composition and heavy metal contents in water, silage, and soil
2019
Zhou, Xuewei | Zheng, Nan | Su, Chuanyou | Wang, Jiaqi | Soyeurt, Hélène
Various industrial activities lead to environmental pollution by heavy metals. Toxic heavy metals enter the food chain of dairy cows through feed and water, then transferred into milk. This study investigated the correlations of heavy metal contents between individual cows’ milk, water, silage and soil. The relationships between heavy metal contents in individual cows’ milk with milk protein, fat, lactose, solid nonfat (SNF), and total solids (TS) were analysed. Concentrations of Pb, As, Cr, and Cd in milk, silage and water were measured by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Lead, Cr, and Cd in soil were measured by Atomic Absorption Spectrometry (AAS), and As was detected by Atomic Fluorescence Spectrometry (AFS). One-way non-parametric tests and Spearman correlation analyses were performed using SAS 9.4 software. Levels of Pb and Cd in milk from the unpolluted area were significantly lower (P < 0.01) than those from industrial area. Significantly higher (P < 0.01) As residue was recorded in milk from unpolluted area. Positive correlation of Pb was observed between milk and silage, and As in milk was positively correlated with As in water. Content of As in milk was slightly (r = 0.09) correlated with As in silage, even though strong positive correlation (r = 0.78) was observed between silage and water. Positive correlations were observed for Cr and Cd between milk and silage, as well as milk and soil. Positive correlations were observed in Pb-protein, Cr-protein, and Cd-lactose; other positive correlation coefficients were nearly equal to zero. The results suggest that industrial activities lead to possible Pb and Cd contamination in milk. Drinking water could be the main source of As contamination in cows. No clear relationship was found between milk composition and heavy metals contents in milk. Water and soil on the farm had a partial contribution to heavy metal contamination in milk.
اظهر المزيد [+] اقل [-]Biochemical and molecular impacts of glyphosate-based herbicide on the gills of common carp
2019
Ma, Junguo | Zhu, Jingyi | Wang, Wanying | Ruan, Panpan | Rajeshkumar, Sivakumar | Li, Xiaoyu
Glyphosate (GLY)-based herbicide, one of the most widely used herbicides, might cause a series of environmental problems and pose a toxicological risk to aquatic organisms. However, data on the potential hazard and toxicity mechanism of GLY to fish gills are relatively scarce. In this study, a subacute toxicity test of common carp (Cyprinus carpio L.) treated with commercial GLY at 52.08 and 104.15 mg L−1 for 7 d was conducted. The results revealed that GLY exposure significantly inhibited Na+/K+-ATPase and increased AST and ALT activities in the fish gills. The biochemical assays results revealed that GLY treatment remarkably altered the transcriptional levels of HSP70 and HSP90; inhibited the activities of SOD, CAT, GPx, GR, and T-AOC; reduced the contents of GSH, but remarkably promoted MDA and PC contents, suggesting that GLY exposure induced oxidative stress and lipids and proteins damage in the carp gills. Further research revealed that GLY exposure also promoted expression of NF-κB, iNOS, IL-1β, IL-6, IL-8, and TNF-α; altered the levels of IL-10 and TGF-β, indicating that GLY exposure induced inflammatory response in the fish gills. Additionally, we found that GLY exposure activated apaf-1 and bax and inhibited bcl-2, induced caspase-9 and caspase-3 expression and caused remarkable histological damage in the fish gills. These results may further enriches the toxicity mechanistic theory of GLY to fish gills, which may be useful for the risk assessment of GLY and aquatic organism protection.
اظهر المزيد [+] اقل [-]Effects of Fe-Mn modified biochar composite treatment on the properties of As-polluted paddy soil
2019
Lin, Lina | Li, Zhongyang | Liu, Xuewei | Qiu, Weiwen | Song, Zhengguo
This study aimed to determine the effects of FeMn modified biochar composite (FMBC) treatment on the pH, redox properties, enzyme activities, and bacterial communities of As-polluted paddy soil. The two utilized FMBCs (FMBC₁ and FMBC₂) exhibited markedly different effects on soil pH, and treatment with biochar (BC) or FMBCs increased the soil redox potential and reduced the content of available As, facilitating the conversion of originally present non-specifically sorbed and specifically bound As forms to residual, amorphous hydrous oxide–bound, and crystalline hydrous oxide–bound ones. In general, the activities of soil enzymes increased after the above treatments, with the exception of that of alkaline phosphatase, which decreased upon supplementation with FMBC₂. Supplementation with BC or FMBCs increased the abundance of Proteobacteria and Firmicutes, decreasing that of Bacteroidetes. Notably, FMBC₁ and FMBC₂ affected soil properties in different ways, although the mechanisms of the corresponding influence were similar. Thus, treatment with BC-based materials changed the distribution of As and the activities of soil enzymes, additionally affecting a variety of other physicochemical soil properties to make it suitable for microbial growth.
اظهر المزيد [+] اقل [-]Atmospheric dispersion of methane emissions from sugarcane burning in Mexico
2019
Flores-Jiménez, David E. | Carbajal, Noel | Algara Siller, Marcos | Aguilar Rivera, Noé | Álvarez-Fuentes, Gregorio | Ávila-Galarza, Alfredo | García, Agustín R.
Methane is a potent greenhouse gas whose atmospheric dispersion may have different implications at distinct scales. One significant contributor to methane emissions is sugarcane farming in tropical areas like in Mexico, which has the sixth highest production level in the world. A consequence of the industrial use of this resource is that sugarcane preharvest burning emits large quantities of methane and other pollutants. The objective of this research is to estimate the methane emissions by sugarcane burning and to analyze their atmospheric dispersion under the influence of meteorological parameters, according to different concentration scenarios generated during a period. The methane emissions were investigated using the methodology of Seiler and Crutzen, based on the stage production during the harvest periods of 2011/2012, 2012/2013 and 2013/2014. Average of total emissions (1.4 × 103 Mg) at the national level was comparable in magnitude to those of other relevant sugarcane-producing countries such as India and Brazil. Satellite images and statistical methods were used to validate the spatial distribution of methane, which was obtained with the WRF model. The results show a dominant wind circulation pattern toward the east in the San Luis Potosi area, to the west in Jalisco, and the north in Tabasco. In the first two areas, wind convergence at a certain height causes a downward flow, preventing methane dispersion. The concentrations in these areas varied from 9.22 × 10−5 to 1.22 × 102 ppmv and 32 × 10−5 to 2.36 × 102 ppmv, respectively. Wind conditions in Tabasco contributed to high dispersion and low concentrations of methane, varying from 8.74 × 105 to 0.33 × 102 ppmv. Methane is a potent greenhouse gas for which it is essential to study and understand their dispersion at different geographic locations and atmospheric conditions.
اظهر المزيد [+] اقل [-]Two decades of monitoring in marine debris ingestion in loggerhead sea turtle, Caretta caretta, from the western Mediterranean
2019
Domènech, F. | Aznar, F.J. | Raga, J.A. | Tomas, J.
Anthropogenic marine debris is one of the major worldwide threats to marine ecosystems. The EU Marine Strategy Framework Directive (MSFD) has established a protocol for data collection on marine debris from the gut contents of the loggerhead sea turtle (Caretta caretta), and for determining assessment values of plastics for Good Environmental Status (GES). GES values are calculated as percent turtles having more than average plastic weight per turtle. In the present study, we quantify marine debris ingestion in 155 loggerhead sea turtles collected in the period 1995–2016 in waters of western Mediterranean (North-east Spain). The study aims (1) to update and standardize debris ingestion data available from this area, (2) to analyse this issue over two decades using Zero-altered (hurdle) models and (3) to provide new data to compare the only GES value available (off Italian waters). The composition of marine debris (occurrence and amounts of different categories) was similar to that found in other studies for the western Mediterranean and their amounts seem not to be an important threat to turtle survival in the region. Model results suggest that, in the study area, (a) period of stranding or capture, (b) turtle size and (c) latitude are significant predictors of anthropogenic debris ingestion (occurrence and amount) in turtles. The GES value for late juvenile turtles (CCL>40 cm) has decreased in the last ten years in the study area, and this is very similar to that obtained in Italian waters. We also provide a GES value for early juvenile turtles (CCL≤40 cm) for the first time. Recommendations arising from this study include ensuring use of (1) the standardized protocol proposed by the MSFD for assessing marine debris ingestion by loggerhead sea turtles and (2) the ecology of the turtles (neritic vs oceanic), rather than their size, to obtain GES values.
اظهر المزيد [+] اقل [-]Distributions of organophosphate flame retardants (OPFRs) in three dust size fractions from homes and building material markets
2019
Zhou, Lingli | Püttmann, Wilhelm
The distributions of organophosphate flame retardants (OPFRs) in various size fractions of indoor dust samples from homes (H; n = 18) and building material markets (B; n = 7) in the Rhine/Main region of Germany were investigated. Three particle size fractions (F1: 150–200 μm, F2: 63–150 μm, and F3: <63 μm) and bulk dust (BD) subsamples (<200 μm) of each sample were analyzed for 10 OPFRs. On average, the total OPFR concentrations (∑10OPFR) in bulk dust and all three size fractions from building material markets were 133, 153, 196, and 88.0 μg/g in subsamples B-BD, B-F1, B-F2, and B-F3. These concentrations were at least five times higher than those in bulk dust and all three size fractions from homes, with values of 19.3, 17.2, 19.5, and 18.7 μg/g for subsamples H-BD, H-F1, H-F2, and H-F3, respectively. Tris(2-chloroisopropyl)phosphate (TCIPP) was the dominant congener in dust from building material markets, contributing over 91% to the ∑10OPFR of B-BD and all particle size fractions. Meanwhile, both tris(2-butoxyethyl)phosphate (TBOEP) and TCIPP were abundant in dust from homes, respectively contributing 28%–41% and 31%–43% to the ∑10OPFR of H-BD and all particle size fractions. Most of the OPFR concentrations showed no consistent trend with particle size. However, TCIPP was more likely to be enriched in F2. Microscopic examination indicated that TCIPP in indoor dust mainly originated from abraded fragments of commercial products. In contrast, TBOEP accumulated in F3, related to direct transfer of floor-care products to fine dust particles. The concentrations of OPFRs were not significantly correlated with total organic carbon contents in any particle size fraction. However, evaluation of their mass contributions showed that more than 85% of OPFRs accumulated in particles smaller than 150 μm, indicating that this particle size fraction is most suitable for monitoring of OPFRs.
اظهر المزيد [+] اقل [-]Sources and dry deposition of carbonaceous aerosols over the coastal East China Sea: Implications for anthropogenic pollutant pathways and deposition
2019
Wang, Fengwen | Feng, Ding | Guo, Zhigang | Li, Yuanyuan | Lin, Tian | Rose, N. L. (Neil L.)
75 paired TSP and PM2.5 samples were collected over four seasons on Huaniao Island (HNI), an island that lies downwind of continental pollutants emitted from mainland China to the East China Sea (ECS). These samples were analyzed for organic carbon (OC) and elemental carbon (EC), with a special focus on char-EC (char) and soot-EC (soot), to understand their sources, and the scale and extent of pollution and dry deposition over the coastal ECS. The results showed that char concentrations in PM2.5 and TSP averaged from 0.13 to 1.01 and 0.31–1.44 μg m−3; while for soot, they were from 0.03 to 0.21 and 0.16–0.56 μg m−3, respectively. 69.0% of the char and 36.4% of the soot were present in PM2.5. The char showed apparent seasonal variations, with highest concentrations in winter and lowest in summer; while soot displayed maximum concentrations in fall and minimum in summer. The char/soot ratios in PM2.5 averaged from 3.29 to 17.22; while for TSP, they were from 1.20 to 7.07. Both of the ratios in PM2.5 and TSP were highest in winter and lowest in fall. Comparisons of seasonal variations in OC/EC and char/soot ratios confirmed that char/soot may be a more effective indicator of carbonaceous aerosol source identification than OC/EC. Annual average atmospheric dry deposition fluxes of OC and EC into ECS were estimated to be 229 and 107 μg m−2 d−1, respectively, and their deposition fluxes significantly increased during episodes. It was estimated that the loadings of OC + EC and EC accounted for 1.3% and 4.1% of the total organic carbon and EC in ECS surface sediments, respectively, implying a relatively small contribution of OC and EC dry deposition to organic carbon burial. This finding also indicates a possibly more important contribution of wet deposition to organic carbon burial in sediments of ECS, and this factor should be considered for future study.
اظهر المزيد [+] اقل [-]Temperature alters susceptibility of Picea abies seedlings to airborne pollutants: The case of CdO nanoparticles
2019
Večeřová, Kristýna | Večeřa, Zbyněk | Mikuška, Pavel | Coufalík, Pavel | Oravec, Michal | Dočekal, Bohumil | Novotna, Katerina | Veselá, Barbora | Pompeiano, Antonio | Urban, Otmar
Although plants are often exposed to atmospheric nanoparticles (NPs), the mechanism of NP deposition and their effects on physiology and metabolism, and particularly in combination with other stressors, are not yet understood. Exploring interactions between stressors is particularly important for understanding plant responses in urban environments where elevated temperatures can be associated with air pollution. Accordingly, 3-year-old spruce seedlings were exposed for 2 weeks to aerial cadmium oxide (CdO) NPs of environmentally relevant size (8–62 nm) and concentration (2 × 10⁵ cm⁻³). While half the seedlings were initially acclimated to high temperature (35 °C) and vapour pressure deficit (VPD; 2.81 kPa), the second half of the plants were left under non-stressed conditions (20 °C, 0.58 kPa). Atomic absorption spectrometry was used to determine Cd content in needles, while gas and liquid chromatography was used to determine changes in primary and secondary metabolites. Photosynthesis-related processes were explored with gas-exchange and chlorophyll fluorescence systems. Our work supports the hypothesis that atmospheric CdO NPs penetrate into leaves but high temperature and VPD reduce such penetration due to stomatal closure. The hypothesis that atmospheric CdO NPs influences physiological and metabolic processes in plants was also confirmed. This impact strengthens with increasing time of exposure. Finally, we found evidence that plants acclimated to stress conditions have different sensitivity to CdO NPs compared to plants not so acclimated. These findings have important consequences for understanding impacts of global warming on plants and indicates that although the effects of elevated temperatures can be deleterious, this may limit other forms of plant stress associated with air pollution.
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