خيارات البحث
النتائج 1751 - 1760 من 6,558
Antibiotics in soil and water in China–a systematic review and source analysis النص الكامل
2020
Lyu, Jia | Yang, Linsheng | Zhang, Lan | Ye, Bixiong | Wang, Li
With the high production and consumption of antibiotics in recent years due to increasing economic development and improving population health, China is facing serious antibiotic pollution in the environment, and it is becoming a significant threat to ecology and human health. This study explores the spatial distribution patterns of 65 antibiotics in soil, surface water and coastal water based on a systematic review. Potential emission sources of antibiotics are also analyzed using data extracted from the reviewed literature. The results suggest that China has very high antibiotic detection rates of 100%, 98.0% and 96.4% for soil, surface water and coastal water, respectively. Regions with high antibiotic levels are mainly located in Bohai Bay, including the Beijing‒Tianjin‒Hebei region, Liaoning and Shandong Provinces, and Yangtze River. Tetracyclines (TCs) and quinolones (QNs) are the dominant antibiotics observed in soil and are mainly attributed to the use of manure as fertilizer and the reuse of domestic wastewater. Sulfonamides (SAs), macrolides (MLs), TCs and QNs are the dominant antibiotics observed in surface water and are mainly attributed to aquaculture and the emission of domestic sewage. QNs are the dominant antibiotics observed in coastal water and are mainly attributed to marine cultivation. The detection frequencies and concentrations of TCs, QNs, SAs and MLs in both soil and water are much higher than those in other developed countries. Suggestions including restricting antibiotic usages in livestock farming and aquaculture, innovation of wastewater treatment technology to improve antibiotic removal rate, and establishing guidelines on antibiotic concentration for wastewater discharge and organic fertilizer are provided.
اظهر المزيد [+] اقل [-]Uptake and dissipation of metalaxyl-M, fludioxonil, cyantraniliprole and thiamethoxam in greenhouse chrysanthemum النص الكامل
2020
Gong, Wenwen | Jiang, Mengyun | Zhang, Tingting | Zhang, Wei | Liang, Gang | Li, Bingru | Hu, Bin | Han, Ping
Production of chrysanthemum (Dendranthema grandiflora) in greenhouses often requires intensive pesticide use, which raises serious concerns over food safety and human health. This study investigated uptake, translocation and residue dissipation of typical fungicides (metalaxyl-M and fludioxonil) and insecticides (cyantraniliprole and thiamethoxam) in greenhouse chrysanthemum when applied in soils. Chrysanthemum plants could absorb these pesticides from soils via roots to various degrees, and bioconcentration factors (BCFLS) were positively correlated with lipophilicity (log Kₒw) of pesticides. Highly lipophilic fludioxonil (log Kₒw = 4.12) had the greatest BCFLS (2.96 ± 0.41 g g⁻¹), whereas hydrophilic thiamethoxam (log Kₒw = −0.13) had the lowest (0.09 ± 0.03 g g⁻¹). Translocation factors (TF) from roots to shoots followed the order of TFₗₑₐf > TFₛₜₑₘ > TFfₗₒwₑᵣ. Metalaxyl-M and cyantraniliprole with medium lipophilicity (log Kₒw of 1.71 and 2.02, respectively) and hydrophilic thiamethoxam showed relatively strong translocation potentials with TF values in the range of 0.29–0.81, 0.36–2.74 and 0.30–1.03, respectively. Dissipation kinetics in chrysanthemum flowers followed the first-order with a half-life of 21.7, 5.5, 10.0 or 8.2 days for metalaxyl-M, fludioxonil, cyantraniliprole and thiamethoxam, respectively. Final residues of these four pesticides, including clothianidin (a primary toxic metabolite of thiamethoxam), in all chrysanthemum flower samples were below the maximum residue limit (MRL) values 21 days after two soil applications each at the recommended dose (i.e., 3.2, 2.1, 4.3 and 4.3 kg ha⁻¹, respectively). However, when doubling the recommended dose, the metabolite clothianidin remained at concentrations greater than the MRL, despite that thiamethoxam concentration was lower than the MRL value. This study provided valuable insights on the uptake and residues of metalaxyl-M, fludioxonil, cyantraniliprole and thiamethoxam (including its metabolite clothianidin) in greenhouse chrysanthemum production, and could help better assess food safety risks of chrysanthemum contamination by parent pesticides and their metabolites.
اظهر المزيد [+] اقل [-]Membrane Enhanced Bioaccessibility Extraction (MEBE) of hydrophobic soil pollutants – Using a semipermeable membrane for separating desorption medium and acceptor solvent النص الكامل
2020
Cocovi-Solberg, David J. | Kellner, Astrid | Schmidt, Stine N. | Loibner, Andreas P. | Miró, Manuel | Mayer, Philipp
Bioaccessibility extractions are increasingly applied to measure the fraction of pollutants in soil, sediment and biochar, which can be released under environmentally or physiologically relevant conditions. However, the bioaccessibility of hydrophobic organic chemicals (HOCs) can be markedly underestimated when the sink capacity of the extraction medium is insufficient. Here, a novel method called “Membrane Enhanced Bioaccessibility Extraction” (MEBE) applies a semipermeable membrane to physically separate an aqueous desorption medium that sets the desorption conditions from an organic medium that serves as acceptor phase and infinite sink. The specific MEBE method combines HOC (1) desorption into a 2-hydroxypropyl-β-cyclodextrin solution, (2) transfer through a low-density polyethylene (LDPE) membrane and (3) release into ethanol, serving as analytical acceptor phase. The surface to volume ratio within the LDPE membrane is maximized for rapid depletion of desorbed molecules, and the capacity ratio between the acceptor phase and the environmental sample is maximized to achieve infinite sink conditions. Several experiments were conducted for developing, optimizing and pre-testing the method, which was then applied to four soils polluted with polycyclic aromatic hydrocarbons. MEBE minimized sample preparation and yielded a solvent extract readily analyzable by HPLC. This study focused on the proof-of-principle testing of the MEBE concept, which now can be extended and applied to other samples and desorption media.
اظهر المزيد [+] اقل [-]Triphenyl phosphate modulated saturation of phospholipids: Induction of endoplasmic reticulum stress and inflammation النص الكامل
2020
Hu, Wenxin | Kang, Qiyue | Zhang, Chenhao | Ma, Haojia | Xu, Chenke | Wan, Yi | Hu, Jianying
Although triphenyl phosphate (TPHP) has been reported to disrupt lipid metabolism, the effect of TPHP on lipid saturation remains unexplored. In this study, a lipidomic analysis demonstrated decreases in the levels of poly-unsaturated phosphatidylcholine (PC), phosphatidylethanolamine (PE), and phosphatidylserine (PS) in RAW264.7 murine macrophage cells exposed to 10 μM TPHP. The expression of the gene encoding lysophosphatidylcholine acyltransferase 3 (Lpcat3) was significantly downregulated by 0.76 ± 0.03 and 0.70 ± 0.08-fold in 10 and 20 μM TPHP exposure groups, relative to the control group. This finding explains the observed decrease in lipid saturation. Correspondingly, exposure to 10 and 20 μM TPHP induced endoplasmic reticulum (ER) stress and inflammatory responses, which have been linked to metabolic dysfunction such as insulin resistance and hypertriglyceridemia. Therefore, TPHP may pose a risk to human health by promoting metabolic diseases.
اظهر المزيد [+] اقل [-]Utilization of domestic wastewater as a water source of Tetradesmusobliquus PF3 for the biological removal of nitric oxide النص الكامل
2020
Ma, Shanshan | Yu, Yanling | Cui, Hao | Li, Jiang | Feng, Yujie
The reduction of nitrogen oxide (DeNOx) from flue gas by microalgae is a promising technology that has attracted increasing attention. Because the water source is a major limitation of microalgae application in the DeNOx from flue gas, we investigated the feasibility of using domestic wastewater (WW) as a water source. As a result, a biomass accumulation rate of 0.27 ± 0.01 mg L⁻¹ d⁻¹ was achieved by Tetradesmusobliquus PF3 cultivated in WW for 8 d, and 30 mg L⁻¹ of nitrate nitrogen was added to the WW to fulfill the nutrient requirements of the microalgae cells. The ammonium (NH₄⁺) nitrogen present in WW exerted inhibitory effects on the removal of nitric oxide (NO), thereby leading to 8% decrease removal efficiency in comparison with that using clean water and nutrients (BG11 medium). However, these inhibitory effects disappeared following the exhaustion of NH₄⁺ by T. obliquus PF3 after 1 d. To overcome the inhibition of NH₄⁺ and to achieve a high NO removal efficiency, a strategy of connecting two reactors in series was presented. The removal efficiency of NO by the two series reactors reached up to 71.2 ± 2.9%, which was significantly higher than that obtained by a single reactor (43.1 ± 3.6%). In addition, 70.9 ± 4.8% of the supplied NO was fixed into microalgae cells in the two reactors, which was 1.75 times higher than that in the single reactor (40.6 ± 5.1%), thereby suggesting that connecting two reactors in series rendered effective recovery of NO from flue gas using WW as a water source. In this study, we provided an economically viable water source for the application of microalgae in the biological DeNOx from flue gases.
اظهر المزيد [+] اقل [-]Factory employment exposure and human health: Evidence from rural China النص الكامل
2020
Xu, Xiangbo | Sun, Mingxing | Zhang, Linxiu | Fu, Chao | Bai, Yunli | Li, Chang
Quantitating the health effects of employment history in factories, especially polluting ones, is essential for understanding the benefits or losses of industrialization in rural areas. Using a traced subset of nationwide panel data from 2005 covering five provinces, 101 villages, and 2026 households (collected recently in 2016) and the econometric models, this study estimated the effect of factory employment history on workers' health. The results showed that: the absolute number of factory workers increased from 1998 to 2015, and the proportion of factory workers was 7.68% in 2015; the absolute number and the proportion of farmers decreased from 63.84% in 1998 to 29.06% in 2015. Given that all the respondents live in rural areas, the HlthPlace (the first place the individual went to for their last illness in 2015) was selected as the main dependent variable of interest, and Hlthexp (Healthcare expenditure per person at last illness in 2015) and self-reported health were used as auxiliary dependent variables. The findings revealed that, after controlling the characteristics of individual, household, hospital and area, a one year increase of factory employment history corresponded to a 0.035 level increase in the probability of people choosing high-level hospital (p < 0.01) and a 237.61 yuan increase in healthcare expenditure (p < 0.1). The results also showed the adverse effect of self-reported health on factory employment history (p < 0.01). In addition, the relationship between the farming history and health was evaluated, and the econometric results showed that compared with factory employment history, farming history had opposite impacts on health (p < 0.01). Finally, the robustness check showed that the empirical results were reliable and that the initial results were robust. Generally, this study revealed the effect of overall factory employment on health, which is a useful research supplement to the studies on the health effects of specific pollution exposure.
اظهر المزيد [+] اقل [-]Effects of microplastics and mercury on manila clam Ruditapes philippinarum: Feeding rate, immunomodulation, histopathology and oxidative stress النص الكامل
2020
Sıkdokur, Ercan | Belivermiş, Murat | Sezer, Narin | Pekmez, Murat | Bulan, Ömür Karabulut | Kılıç, Önder
Plastic pollution, which is one of the most important environmental problems at the present time, has been understood recently, and the effects of this pollution on ecosystem and biota are becoming a growing problem, especially in the aquatic ecosystems. Direct or indirect exposure to those particles leads to adverse effects on marine organisms. In the marine environment, plastic materials interact with other pollutants such as metals, thereby affecting the uptake levels of those pollutants in marine organisms. In the present study, the Manila clam Ruditapes philippinarum was exposed to polyethylene microbeads and mercury chloride in single, combined and incubated form at environmentally relative concentrations for one week in controlled laboratory conditions. The uptake and tissue distribution of both stressors as well as the vector role of microplastics on mercury uptake in the organisms were investigated. Filtration rates, biomarkers for immunomodulation and oxidative stress, and histological alterations were also evaluated. Microplastics were ingested by the clams, and translocated to the various tissues. However, contaminated microplastics displayed a negligible vector role in terms of mercury bioaccumulation in the clams. The single and interactive exposure of the stressors reduced the filtration rate in the clams. Both pollutants affected the immune system of the organisms. Histological alterations were determined in the gill and digestive gland tissues of the clams among the treatment groups, although oxidative stress biomarkers remained unchanged. This study suggests that the vector role of polyethylene microplastics in mercury uptake is negligible and reveals that the single and interactive one-week exposure of two pollutants induce toxicity in the manila clams.
اظهر المزيد [+] اقل [-]Antibiotic resistance genes, bacterial communities, and functions in constructed wetland-microbial fuel cells: Responses to the co-stresses of antibiotics and zinc النص الكامل
2020
Li, Hua | Xu, Han | Song, Hai-Liang | Lu, Yi | Yang, Xl (Xiaoli)
The effects of the continuous accumulation of Zinc (Zn) on the fate of antibiotic resistance genes (ARGs) in constructed wetland-microbial fuel cells (CW-MFCs) remain unclear. In this study, the impacts of Zn addition and a circuit mode on antibiotic removal, occurrence of ARGs, the bacterial community, and bacterial functions were investigated in three groups of CW-MFCs. The results showed that continuous Zn exposure enriched the target ARGs during the initial stage, while excessive Zn accumulation decreased antibiotic removal and the abundance of ARGs. A principal component analysis demonstrated that ARGs and the bacterial community distribution characteristics were significantly impacted by the mass accumulation of antibiotics and Zn, as well as the circuit mode. A redundancy analysis, partial least squares path modeling, and Procrustes analysis revealed that the accumulation of antibiotics and Zn, the composition of the bacterial community, the circuit mode, and the abundance of intI associated with horizontal gene transfer jointly contributed to the distributions of ARGs in the electrodes and effluent. Moreover, continuous exposure to Zn decreased the bacterial diversity and changed the composition and function of the bacterial community predicted using PICRUSt tool. The co-occurrence of ARGs, their potential hosts and bacterial functions were further revealed using a network analysis. A variation partition analysis also showed that the accumulation of target pollutants and the circuit mode had a significant impact on the bacterial community composition and functions. Therefore, the interaction among ARGs, the bacterial community, bacterial functions, and pollutant accumulations in the CW-MFC was complex. This study provides useful implications for the application of CW-MFCs for the treatment of wastewater contaminated with antibiotics and heavy metals.
اظهر المزيد [+] اقل [-]Lead bioavailability in different fractions of mining- and smelting-contaminated soils based on a sequential extraction and mouse kidney model النص الكامل
2020
Li, Shi-Wei | Li, Meng-Ya | Sun, Hong-Jie | Li, Hong-Bo | Ma, Lena Q.
Lead bioavailability in contaminated soils varies considerably depending on Pb speciation and sources of contamination. However, little information is available on bioavailability of Pb associated with different fractions. In this study, the Tessier sequential extraction was used to fractionate Pb in 3 contaminated soils to exchangeable (F1), carbonate-bound (F2), Fe/Mn oxides-bound (F3), organic-bound (F4), and residual fractions (F5). In addition, soil residues after F1–F2 extraction (F₃₄₅), F1–F3 extraction (F₄₅), and F1–F4 extraction (F₅) were measured for Pb relative bioavailability (RBA) using a mouse kidney model. Based on the mouse model, Pb-RBA in the soils was 44–93%, which decreased to 43–89%, 28–75%, and 15–68% in the F₃₄₅, F₄₅, and F₅ fractions, respectively. Based on Pb-RBA in the soil residues, Pb-RBA in different fractions was calculated based on a mass balance. The data showed that Pb-RBA was the highest (∼100%) in the exchangeable and carbonate fraction, and the lowest (15–68%) in the residual fraction. In addition, Pb in the first three fractions (F1–F3) contributed most (83–89%) to bioavailable Pb in contaminated soils. Our study shed light on oral bioavailability of Pb in contaminated soils of different fractions based on sequential extraction and provide important information for soil remediation.
اظهر المزيد [+] اقل [-]Application of advanced HepG2 3D cell model for studying genotoxic activity of cyanobacterial toxin cylindrospermopsin النص الكامل
2020
Hercog, Klara | Štampar, Martina | Štern, Alja | Filipič, Metka | Žegura, Bojana
Cylindrospermopsin (CYN) is an emerging cyanotoxin increasingly being found in freshwater cyanobacterial blooms worldwide. Humans and animals are exposed to CYN through the consumption of contaminated water and food as well as occupational and recreational water activities; therefore, it represents a potential health threat. It exhibits genotoxic effects in metabolically active test systems, thus it is considered as pro-genotoxic. In the present study, the advanced 3D cell model developed from human hepatocellular carcinoma (HepG2) cells was used for the evaluation of CYN cyto-/genotoxic activity. Spheroids were formed by forced floating method and were cultured for three days under static conditions prior to exposure to CYN (0.125, 0.25 and 0.5 μg/mL) for 72 h. CYN influence on spheroid growth was measured daily and cell survival was determined by MTS assay and live/dead staining. The influence on cell proliferation, cell cycle alterations and induction of DNA damage (γH2AX) was determined using flow cytometry. Further, the expression of selected genes (qPCR) involved in the metabolism of xenobiotics, proliferation, DNA damage response, apoptosis and oxidative stress was studied. Results revealed that CYN dose-dependently reduced the size of spheroids and affected cell division by arresting HepG2 cells in G1 phase of the cell cycle. No induction of DNA double strand breaks compared to control was determined at applied conditions. The analysis of gene expression revealed that CYN significantly deregulated genes encoding phase I (CYP1A1, CYP1A2, CYP3A4, ALDH3A) and II (NAT1, NAT2, SULT1B1, SULT1C2, UGT1A1, UGT2B7) enzymes as well as genes involved in cell proliferation (PCNA, TOP2α), apoptosis (BBC3) and DNA damage response (GADD45a, CDKN1A, ERCC4). The advanced 3D HepG2 cell model due to its more complex structure and improved cellular interactions provides more physiologically relevant information and more predictive data for human exposure, and can thus contribute to more reliable genotoxicity assessment of chemicals including cyanotoxins.
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