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BACKGROUND: Nursing home residents are at high risk for infection, hospitalization, and colonization with multidrug-resistant organisms. METHODS: We performed a cluster-randomized trial of universal decolonization as compared with routine-care bathing in nursing homes. The trial included an 18-month baseline period and an 18-month intervention period. Decolonization entailed the use of chlorhexidine for all routine bathing and showering and administration of nasal povidone-iodine twice daily for the first 5 days after admission and then twice daily for 5 days every other week. The primary outcome was transfer to a hospital due to infection. The secondary outcome was transfer to a hospital for any reason. An intention-to-treat (as-assigned) difference-in-differences analysis was performed for each outcome with the use of generalized linear mixed models to compare the intervention period with the baseline period across trial groups. RESULTS: Data were obtained from 28 nursing homes with a total of 28,956 residents. Among the transfers to a hospital in the routine-care group, 62.2% (the mean across facilities) were due to infection during the baseline period and 62.6% were due to infection during the intervention period (risk ratio, 1.00; 95% confidence interval [CI], 0.96 to 1.04). The corresponding values in the decolonization group were 62.9% and 52.2% (risk ratio, 0.83; 95% CI, 0.79 to 0.88), for a difference in risk ratio, as compared with routine care, of 16.6% (95% CI, 11.0 to 21.8; P<0.001). Among the discharges from the nursing home in the routine-care group, transfer to a hospital for any reason accounted for 36.6% during the baseline period and for 39.2% during the intervention period (risk ratio, 1.08; 95% CI, 1.04 to 1.12). The corresponding values in the decolonization group were 35.5% and 32.4% (risk ratio, 0.92; 95% CI, 0.88 to 0.96), for a difference in risk ratio, as compared with routine care, of 14.6% (95% CI, 9.7 to 19.2). The number needed to treat was 9.7 to prevent one infection-related hospitalization and 8.9 to prevent one hospitalization for any reason. CONCLUSIONS: In nursing homes, universal decolonization with chlorhexidine and nasal iodophor led to a significantly lower risk of transfer to a hospital due to infection than routine care. (Funded by the Agency for Healthcare Research and Quality; Protect ClinicalTrials.gov number, NCT03118232.).
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Antiinfecciosos Locales , Infecciones Asintomáticas , Clorhexidina , Infección Hospitalaria , Casas de Salud , Povidona Yodada , Humanos , Administración Cutánea , Administración Intranasal , Antiinfecciosos Locales/administración & dosificación , Antiinfecciosos Locales/uso terapéutico , Baños , Clorhexidina/administración & dosificación , Clorhexidina/uso terapéutico , Infección Hospitalaria/epidemiología , Infección Hospitalaria/prevención & control , Infección Hospitalaria/terapia , Hospitalización/estadística & datos numéricos , Casas de Salud/estadística & datos numéricos , Transferencia de Pacientes/estadística & datos numéricos , Povidona Yodada/administración & dosificación , Povidona Yodada/uso terapéutico , Cuidados de la Piel/métodos , Infecciones Asintomáticas/terapiaRESUMEN
Type III interferons (IFN-lambdas(λ)) are important cytokines that inhibit viruses and modulate immune responses by acting through a unique IFN-λR1/IL-10RB heterodimeric receptor. Until now, the primary antiviral function of IFN-λs has been proposed to be at anatomical barrier sites. Here, we examine the regulation of IFN-λR1 expression and measure the downstream effects of IFN-λ3 stimulation in primary human blood immune cells, compared with lung or liver epithelial cells. IFN-λ3 directly bound and upregulated IFN-stimulated gene (ISG) expression in freshly purified human B cells and CD8+ T cells, but not monocytes, neutrophils, natural killer cells, and CD4+ T cells. Despite similar IFNLR1 transcript levels in B cells and lung epithelial cells, lung epithelial cells bound more IFN-λ3, which resulted in a 50-fold greater ISG induction when compared to B cells. The reduced response of B cells could be explained by higher expression of the soluble variant of IFN-λR1 (sIFN-λR1), which significantly reduced ISG induction when added with IFN-λ3 to peripheral blood mononuclear cells or liver epithelial cells. T-cell receptor stimulation potently, and specifically, upregulated membrane-bound IFNLR1 expression in CD4+ T cells, leading to greater antiviral gene induction, and inhibition of human immunodeficiency virus type 1 infection. Collectively, our data demonstrate IFN-λ3 directly interacts with the human adaptive immune system, unlike what has been previously shown in published mouse models, and that type III IFNs could be potentially utilized to suppress both mucosal and blood-borne viral infections.
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Interferones/farmacología , Receptores de Interferón/biosíntesis , Animales , Linfocitos B/efectos de los fármacos , Linfocitos B/inmunología , Linfocitos T CD4-Positivos/inmunología , Línea Celular , Células Epiteliales/metabolismo , Expresión Génica , Infecciones por VIH/inmunología , Infecciones por VIH/patología , Infecciones por VIH/virología , VIH-1/inmunología , Humanos , Interferón alfa-2/farmacología , Interferones/inmunología , Leucocitos Mononucleares/inmunología , Leucocitos Mononucleares/metabolismo , Hígado/metabolismo , Hígado/patología , Pulmón/metabolismo , Pulmón/patología , Ratones , Empalme del ARN , Receptores de Interferón/genética , Receptores de Interferón/inmunología , Virosis/genética , Virosis/inmunología , Virosis/metabolismo , Interferón lambdaRESUMEN
Zika virus (ZIKV) is an emerging pathogen that can cause microcephaly and other neurological defects in developing fetuses. The cellular response to ZIKV in the fetal brain is not well understood. Here, we show that ZIKV infection of human fetal astrocytes (HFAs), the most abundant cell type in the brain, results in elevated expression and secretion of fibroblast growth factor 2 (FGF2). This cytokine was shown to enhance replication and spread of ZIKV in HFAs and human fetal brain explants. The proviral effect of FGF2 is likely mediated in part by suppression of the interferon response, which would represent a novel mechanism by which viruses antagonize host antiviral defenses. We posit that FGF2-enhanced virus replication in the fetal brain contributes to the neurodevelopmental disorders associated with in utero ZIKV infection. As such, targeting FGF2-dependent signaling should be explored further as a strategy to limit replication of ZIKV.
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Factor 2 de Crecimiento de Fibroblastos/metabolismo , Microcefalia/patología , Replicación Viral , Infección por el Virus Zika/patología , Virus Zika/patogenicidad , Feto Abortado , Aedes , Animales , Astrocitos/inmunología , Astrocitos/patología , Astrocitos/virología , Encéfalo/citología , Línea Celular , Humanos , Interferones/inmunología , Microcefalia/virología , Cultivo Primario de Células , Técnicas de Cultivo de Tejidos , Virus Zika/inmunología , Infección por el Virus Zika/virologíaRESUMEN
Voxilaprevir is a direct-acting antiviral agent (DAA) that targets the NS3/4A protease of hepatitis C virus (HCV). High sequence diversity of HCV and inadequate drug exposure during unsuccessful treatment may lead to the accumulation of variants with reduced susceptibility to DAAs, including NS3/4A protease inhibitors such as voxilaprevir. The voxilaprevir susceptibility of clinical and laboratory strains of HCV was assessed. The NS3 protease regions of viruses belonging to 6 genotypes and 29 subtypes from 345 DAA-naive or -experienced (including protease inhibitor) patients and 344 genotype 1 to 6 replicons bearing engineered NS3 resistance-associated substitutions (RASs) were tested in transient-transfection assays. The median voxilaprevir 50% effective concentration against NS3 from protease inhibitor-naive patient samples ranged from 0.38 nM for genotype 1 to 5.8 nM for genotype 3. Voxilaprevir susceptibilities of HCV replicons with NS3 RASs were dependent on subtype background and the type and number of substitutions introduced. The majority of RASs known to confer resistance to other protease inhibitors had little to no impact on voxilaprevir susceptibility, except A156L, T, or V in genotype 1 to 4 which conferred >100-fold reductions but exhibited low replication capacity in most genotypes. These data support the use of voxilaprevir in combination with other DAAs in DAA-naive and DAA-experienced patients infected with any subtype of HCV.
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Antivirales/farmacología , Hepacivirus/efectos de los fármacos , Compuestos Macrocíclicos/farmacología , Inhibidores de Proteasas/farmacología , Sulfonamidas/farmacología , Proteínas no Estructurales Virales/antagonistas & inhibidores , Sustitución de Aminoácidos , Ácidos Aminoisobutíricos , Ciclopropanos , Farmacorresistencia Viral/genética , Genotipo , Hepacivirus/genética , Hepatitis C Crónica/virología , Humanos , Lactamas Macrocíclicas , Leucina/análogos & derivados , Prolina/análogos & derivados , QuinoxalinasRESUMEN
Velpatasvir is a pan-genotypic hepatitis C virus (HCV) NS5A inhibitor, which is used with sofosbuvir for treatment of infection with HCV genotypes 1-6. In vitro resistance studies were performed to characterize NS5A changes that might confer reduced velpatasvir susceptibility in vivo. Resistance selection studies using HCV replicon cells for subtypes 1a, 1b, 2a, 2b, 3a, 4a, 5a and 6a identified NS5A resistance-associated substitutions (RASs) at nine positions, most often 28M/S/T, 31F/I/M/P/V and 93D/H/N/S. In subtype 1a, RASs were selected at positions 31 and/or 93, while in subtype 1b, replicons with two or more RASs at positions 31, 54 or 93 were selected. Y93H was selected in subtypes 1a, 1b, 2a, 3a and 4a. In subtype 5a or 6a, L31P or P32L/Q was selected, respectively. Velpatasvir susceptibility of 358 replicons from genotypes 1 to 6 containing one or more NS5A RASs was also evaluated. The majority (63%) of subtypes 1a and 1b single RAS-containing replicons retained susceptibility to velpatasvir (<2.5-fold change in EC50 ). High levels of resistance to velpatasvir were observed for six single mutants in subtype 1a, including M28G, A92K, Y93H/N/R/W and for one mutant, A92K, in subtype 1b. Most single mutants in subtypes 2a, 2b, 3a, 4a and 5a displayed low levels of reduced velpatasvir susceptibility. High-level resistance was observed for C92T and Y93H/N in subtype 2b, Y93H/S in 3a, and L31V and P32A/L/Q/R in 6a, and several double mutants in these subtypes. Overall, velpatasvir maintained activity against most common RASs that are known to confer resistance to first-generation NS5A inhibitors.
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Antivirales/farmacología , Carbamatos/farmacología , Farmacorresistencia Viral , Hepacivirus/efectos de los fármacos , Compuestos Heterocíclicos de 4 o más Anillos/farmacología , Proteínas no Estructurales Virales/antagonistas & inhibidores , Línea Celular Tumoral , Farmacorresistencia Viral/efectos de los fármacos , Farmacorresistencia Viral/genética , Genotipo , Hepacivirus/genética , Humanos , Mutación , Replicón/genéticaRESUMEN
Pendrin is a transmembrane chloride/anion antiporter that is strongly upregulated in the airways in rhinoviral infection, asthma, cystic fibrosis and chronic rhinosinusitis. Based on its role in the regulation of airway surface liquid depth, pendrin inhibitors have potential indications for treatment of inflammatory airways diseases. Here, a completely regioselective route to tetrahydro-pyrazolopyridine pendrin inhibitors based on 1,3-diketone and substituted hydrazine condensation was been developed. Structure-activity relationships at the tetrahydropyridyl nitrogen were investigated using a focused library, establishing the privileged nature of N-phenyl ureas and improving inhibitor potency by greater than 2-fold.
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Pirazoles/farmacología , Piridinas/farmacología , Transportadores de Sulfato/antagonistas & inhibidores , Animales , Ratones , Estructura Molecular , Pirazoles/síntesis química , Piridinas/síntesis química , Ratas Endogámicas F344 , Bibliotecas de Moléculas Pequeñas/síntesis química , Bibliotecas de Moléculas Pequeñas/farmacología , Relación Estructura-ActividadRESUMEN
BACKGROUND: The establishment of microbial communities in neonatal mammals plays a pivotal role in shaping their immune responses to infections and other immune-related conditions. This process is influenced by a combination of endogenous and exogenous factors. Previously, we reported that depletion of CD71 + erythroid cells (CECs) results in an inflammatory response to microbial communities in newborn mice. RESULTS: Here, we systemically tested this hypothesis and observed that the small intestinal lamina propria of neonatal mice had the highest frequency of CECs during the early days of life. This high abundance of CECs was attributed to erythropoiesis niches within the small intestinal tissues. Notably, the removal of CECs from the intestinal tissues by the anti-CD71 antibody disrupted immune homeostasis. This disruption was evident by alteration in the expression of antimicrobial peptides (AMPs), toll-like receptors (TLRs), inflammatory cytokines/chemokines, and resulting in microbial dysbiosis. Intriguingly, these alterations in microbial communities persisted when tested 5 weeks post-treatment, with a more notable effect observed in female mice. This illustrates a sex-dependent association between CECs and neonatal microbiome modulation. Moreover, we extended our studies on pregnant mice, observing that modulating CECs substantially alters the frequency and diversity of their microbial communities. Finally, we found a significantly lower proportion of CECs in the cord blood of pre-term human newborns, suggesting a potential role in dysregulated immune responses to microbial communities in the gut. CONCLUSIONS: Our findings provide novel insights into pivotal role of CECs in immune homeostasis and swift adaptation of microbial communities in newborns. Despite the complexity of the cellular biology of the gut, our findings shed light on the previously unappreciated role of CECs in the dialogue between the microbiota and immune system. These findings have significant implications for human health. Video Abstract.
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Animales Recién Nacidos , Antígenos CD , Células Eritroides , Microbioma Gastrointestinal , Receptores de Transferrina , Animales , Femenino , Ratones , Embarazo , Antígenos CD/metabolismo , Células Eritroides/inmunología , Receptores de Transferrina/metabolismo , Masculino , Simbiosis , Disbiosis/microbiología , Humanos , Ratones Endogámicos C57BL , Intestino Delgado/microbiología , Intestino Delgado/inmunologíaRESUMEN
Epicardial adipose tissue (EAT) may enhance the risk of coronary artery disease (CAD). We investigated the relationship between EAT density (a maker of local inflammation) and coronary plaque characteristics in stable CAD patients. This study included 123 individuals who underwent coronary artery calcium scan and coronary CT angiography to evaluate CAD. Plaque characteristics were analyzed by semi-automated software (QAngio, Leiden, Netherlands). Non-contrast CT scans were used to measure EAT density (HU) and volume (cc) (Philips, Cleveland, OH). Multivariate regression models were used to evaluate the association of EAT density and volume with different plaque types. The mean (SD) age was 59.4±10.1 years, 53% were male, the mean (SD) EAT density was -77.2±4.6 HU and the volume was 118.5±41.2 cc. After adjustment for cardiovascular risk factors, EAT density was associated with fibrous fatty (FF) plaque (p<0.03). A 1 unit increase in HU was associated with a 7% higher FF plaque, and lower EAT density is independently associated to FF plaque. The association between EAT density and fibrous (p=0.08), and total noncalcified (p=0.09) plaque trended toward but did not reach significance. There was no association between EAT volume and any plaque type. These results suggest that inflammatory EAT may promote coronary atherosclerosis. Therefore, non-contrast cardiac CT evaluation of EAT quality can help better assess cardiovascular risk.
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There is an urgent need to better understand the impact of different severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants on immune response and disease dynamics to facilitate better intervention strategies. Here, we show that SARS-CoV-2 variants differentially affect host immune responses. The magnitude and quantity of cytokines and chemokines were comparable in those infected with the Wuhan strain and the Delta variant. However, individuals infected with the Omicron variant had significantly lower levels of these mediators. We also found an elevation of plasma galectins (Gal-3, Gal-8, and Gal-9) in infected individuals, in particular, in those with the original strain. Soluble galectins exert a proinflammatory role in COVID-19 pathogenesis. This was illustrated by their correlation with the plasma levels of sCD14, sCD163, enhanced TNF-α/IL-6 secretion, and increased SARS-CoV-2 infectivity in vitro. Moreover, we observed enhanced CD4+ and CD8+ T cell activation in Wuhan strain-infected individuals. Surprisingly, there was a more pronounced T cell activation in those infected with the Omicron in comparison to the Delta variant. In line with T cell activation status, we observed a more pronounced expansion of T cells expressing different co-inhibitory receptors in patients infected with the Wuhan strain, followed by the Omicron and Delta variants. Individuals infected with the Wuhan strain or the Omicron variant had a similar pattern of plasma soluble immune checkpoints. Our results imply that a milder innate immune response might be beneficial and protective in those infected with the Omicron variant. Our results provide a novel insight into the differential impact of SARS-CoV-2 variants on host immunity. IMPORTANCE There is a need to better understand how different SARS-CoV-2 variants influence the immune system and disease dynamics to facilitate the development of better vaccines and therapies. We compared immune responses in 140 SARS-CoV-2-infected individuals with the Wuhan strain, the Delta variant, or the Omicron variant. All these patients were admitted to the intensive care unit and were SARS-CoV-2 vaccination naïve. We found that SARS-CoV-2 variants differentially affect the host immune response. This was done by measuring soluble biomarkers in their plasma and examining different immune cells. Overall, we found that the magnitude of cytokine storm in individuals infected with the Wuhan strain or the Delta variant was greater than in those infected with the Omicron variant. In light of enhanced cytokine release syndrome in individuals infected with the Wuhan strain or the Delta variant, we believe that a milder innate immune response might be beneficial and protective in those infected with the Omicron variant.
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BACKGROUND: Immune checkpoint inhibitors (ICIs) have revolutionized the treatment of cancer. However, only a portion of patients respond to such treatments. Therefore, it remains a prevailing clinical need to identify factors associated with acquired resistance or lack of response to ICIs. We hypothesized that the immunosuppressive CD71+ erythroid cells (CECs) within the tumor and/or distant 'out-of-field' may impair antitumor response. METHODS: We studied 38 patients with cancer through a phase II clinical trial investigating the effects of oral valproate combined with avelumab (anti-programmed death-ligand 1 (PD-L1)) in virus-associated solid tumors (VASTs). We quantified the frequency/functionality of CECs in blood and biopsies of patients. Also, we established an animal model of melanoma (B16-F10) to investigate the possible effects of erythropoietin (EPO) treatment on anti-PD-L1 therapy. RESULTS: We found a substantial expansion of CECs in the blood of patients with VAST compared with healthy controls. We noted that the frequency of CECs in circulation was significantly higher at the baseline and throughout the study in non-responders versus responders to PD-L1 therapy. Moreover, we observed that CECs in a dose-dependent manner suppress effector functions of autologous T cells in vitro. The subpopulation of CD45+CECs appears to have a more robust immunosuppressive property compared with their CD45- counterparts. This was illustrated by a stronger expression of reactive oxygen species, PD-L1/PD-L2, and V-domain Ig suppressor of T-cell activation in this subpopulation. Lastly, we found a higher frequency of CECs in the blood circulation at the later cancer stage and their abundance was associated with anemia, and a poor response to immunotherapy. Finally, we report the expansion of CECs in the spleen and tumor microenvironment of mice with melanoma. We found that although CECs in tumor-bearing mice secret artemin, this was not the case for VAST-derived CECs in humans. Notably, our results imply that EPO, a frequently used drug for anemia treatment in patients with cancer, may promote the generation of CECs and subsequently abrogates the therapeutic effects of ICIs (eg, anti-PD-L1). CONCLUSIONS: Our results demonstrate that anemia by the expansion of CECs may enhance cancer progression. Notably, measuring the frequency of CECs may serve as a valuable biomarker to predict immunotherapy outcomes.
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Melanoma , Linfocitos T , Humanos , Animales , Ratones , Linfocitos T/patología , Inmunoterapia/métodos , Células Eritroides/patología , Estadificación de Neoplasias , Microambiente TumoralRESUMEN
Mercury is a neurotoxin that, unlike many localized industrial pollutants, spreads globally through atmospheric transport. Mercury in the atmosphere is operationally partitioned into gaseous elemental mercury (GEM), gaseous oxidized mercury (GOM), and particulate-bound mercury (TPM). Although GOM makes up only a small fraction of Hg in the free troposphere under normal conditions, its role in the dry and wet deposition of mercury makes GOM a significant species for understanding the transport and fate of mercury in the atmosphere. Although instruments for atmospheric mercury speciation are commercially available, significant uncertainty is associated with the current speciation methods, from sample collection to calibration, for GOM measurements. This paper examines the custom-made calibration sources that have been developed for GOM measuring instruments, evaluates the factors influencing the source performance, and synthesizes recommendations for the design and operation of GOM calibration sources in the future.
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Interleukin-7 is a cytokine with well-established roles in lymphocyte development and more recently, an expanded role in immune function. IL-7Rα is highly expressed by innate lymphoid cells (ILCs), but how IL-7 directs the development or function of ILCs is not well studied. Using mice with inducible deletion of IL-7Rα, we showed that loss of IL-7 signaling led to impaired production of IL-5, IL-13 and amphiregulin in lung ST2+ group 2 innate lymphoid cells (ILC2s) following influenza/A infection. Conversely, mice treated with IL-7 increased production of IL-5 and IL-13 by lung ILC2s. Moreover, we showed that IL-7 enhanced GATA3 and CD25 expression in ILC2s and loss of IL-7 signaling led to their reduced expression. Altogether, this study demonstrates that IL-7 regulates the function of ILC2s during airway viral infection and induces GATA3 and CD25 expression.
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Citocinas , Interleucina-13 , Ratones , Animales , Citocinas/metabolismo , Inmunidad Innata , Interleucina-7 , Anfirregulina , Interleucina-33 , Proteína 1 Similar al Receptor de Interleucina-1 , Interleucina-5 , Linfocitos , Pulmón , Ratones Endogámicos C57BL , Factor de Transcripción GATA3/genéticaRESUMEN
We performed secondary analyses of a postdischarge decolonization trial of MRSA carriers that reduced MRSA infection and hospitalization by 30%. Hospitalized MRSA infection was associated with 7.9 days of non-MRSA antibiotics and CDI in 3.9%. Preventing MRSA infection and associated hospitalization may reduce antibiotic use and CDI incidence.
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Infecciones por Clostridium , Infección Hospitalaria , Staphylococcus aureus Resistente a Meticilina , Infecciones Estafilocócicas , Cuidados Posteriores , Antibacterianos/uso terapéutico , Infecciones por Clostridium/tratamiento farmacológico , Infecciones por Clostridium/epidemiología , Infecciones por Clostridium/prevención & control , Infección Hospitalaria/tratamiento farmacológico , Infección Hospitalaria/epidemiología , Infección Hospitalaria/prevención & control , Humanos , Alta del Paciente , Infecciones Estafilocócicas/tratamiento farmacológico , Infecciones Estafilocócicas/epidemiología , Infecciones Estafilocócicas/prevención & controlRESUMEN
Total concentrations of eight potentially toxic heavy metals (Ba, Cd, Cr, Cu, Mn, Ni, Pb, and Zn) in indoor settled dusts from houses, offices, classrooms, and laboratories in the Greater Toronto Area (GTA), Canada were determined, and the results were compared. The concentrations of these metals were determined through microwave digestion followed by quantification using inductively coupled plasma atomic emission spectroscopy (ICP-AES). The results indicated that the values of heavy metal concentrations in indoor settled dust vary with different indoor environments, with the highest levels found in laboratory dusts (Ba: 152â¯mgâ¯kg-1; Cd: 12â¯mgâ¯kg-1; Cr: 87â¯mgâ¯kg-1; Cu: 411â¯mgâ¯kg-1; Mn: 216â¯mgâ¯kg-1; Ni: 146â¯mgâ¯kg-1; Pb: 86â¯mgâ¯kg-1; Zn: 3571â¯mgâ¯kg-1), while the metal concentrations (except for Mn and Zn) in households, offices, and classroom dusts were lower (0.5-0.67â¯×â¯the laboratory dust values), and comparable to one another. While all the metals studied show an enrichment factor (EF) greater than one, the EF for Cd, Cu, Pb, and Zn ranged from 15 to 554, indicating significant anthropogenic internal sources of these metals.
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An intensive field campaign for the measurement of total gaseous mercury (TGM) concentrations in ambient air was conducted in Changbai Mountain area from 5 August 2005 to 5 July 2006 using an automatic atmospheric mercury analyzer (Tekran 2537A), which was the first time TGM was monitored at a remote area in northeastern China. 99% of the hourly TGM concentrations fell between 1.28 and 9.49ngm(-3) with an annual arithmetic mean of 3.58+/-1.78ngm(-3), which was significantly elevated compared to values obtained in remote areas of Europe and North America. Seasonal mean TGM concentrations displayed a descending trend as follows: winter, spring, fall, and summer. Compared to spring/winter, TGM concentrations were lower in the summer/fall but the standard deviation (SD) of TGM levels was higher and indicated a correlation with anthropogenic emissions. TGM concentrations showed seasonal differences with respect to meteorological parameters: TGM levels in spring/winter were most correlated with wind speed, and correlated with solar radiation only in the winter, while TGM levels in summer/fall periods were most correlated with air temperature. There was a strong diurnal variation of seasonal TGM with significantly higher concentrations in daytime/nighttime compared to the early morning. The seasonal diel TGM pattern indicated regional biofuel and coal combustion were the primary mercury sources.
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Contaminantes Atmosféricos/análisis , Monitoreo del Ambiente , Mercurio/análisis , Estaciones del Año , Altitud , China , Combustibles Fósiles , Gases/análisis , Conceptos MeteorológicosRESUMEN
Reactive gaseous mercury (RGM) and particulate mercury (Hgp) concentrations in ambient air from a remote site at Changbai Mountain area in northeastern China were intermittently monitored from August 2005 to July 2006 totaling 93 days representing fall, winter-spring and summer season, respectively. Rainwater and snow samples were collected during a whole year, and total mercury (THg) in rain samples were used to calculate wet depositional flux. A throughfall method and a model method were used to estimate dry depositional flux. Results showed mean concentrations of RGM and Hgp are 65 and 77 pg m(-3). Compared to background concentrations of atmospheric mercury species in Northern Hemisphere, RGM and Hgp are significantly elevated in Changbai area. Large values for standard deviation indicated fast reactivity and a low residence time for these mercury species. Seasonal variability is also important, with lower mercury levels in summer compared to other seasons, which is attributed to scavenging by rainfall and low local mercury emissions in summer. THg concentrations ranged from 11.5 to 15.9 ng L(-1) in rainwater samples and 14.9-18.6 ng L(-1) in throughfall samples. Wet depositional flux in Changbai area is calculated to be 8.4 microg m(-2) a(-1), and dry deposition flux is estimated to be 16.5 microg m(-2) a(-1) according to a throughfall method and 20.2 microg m(-2) a(-1) using a model method.
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Contaminantes Atmosféricos/análisis , Aire/análisis , Monitoreo del Ambiente/métodos , Mercurio/análisis , Material Particulado/análisis , Aire/normas , China , Gases/análisis , Conceptos Meteorológicos , Estaciones del AñoRESUMEN
Real-time concentrations of atmospheric gaseous elemental mercury (GEM), reactive gaseous mercury (RGM), and mercury associated with particles having sizes <2.5 microm (P-Hg < 2.5) were simultaneously measured in downtown Toronto from December 2003 to November 2004. The annual mean concentrations of GEM, P-Hg < 2.5 and RGM were 4.5 +/- 3.1 ng m(-3) (99.2%), 21.5 +/- 16.4 pg m(-3) (0.5%) and 14.2 +/- 13.2 pg m(-3) (0.3%), respectively. The concentrations for all the measured Hg species were highly variable throughout the year and were lower in winter than in the other three seasons. The maximum concentrations of Hg species were observed in June and were a result of the high number of Hg spikes (using [GEM] >10 ng m(-3) as an indicator) that occurred in the month. Nighttime (between 9pm-6am) concentrations of Hg species were higher than those of daytime. The results revealed: (1) an urban area is a continuous source of Hg species that have the potential to pose impacts on local, regional and global scales; (2) local/regional anthropogenic sources contributed significantly to the levels and the distributions of the Hg species in the urban atmosphere. More studies are needed to identify and quantify the anthropogenic sources of Hg and the Hg species emitted from these sources; (3) surface emission and photochemical reactions (including the reactions involving ozone) did not have significant influence on the levels of Hg species and their distribution in the urban atmosphere.
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Contaminantes Atmosféricos/química , Mercurio/química , Monitoreo del Ambiente , Ontario , Temperatura , Factores de Tiempo , VientoRESUMEN
Samples of water, soil, sediment, and pomegranate were collected from Xi'an and the Qinshihuang Mausoleum in Shaanxi Province, China to assess the effects of human activities on mercury in the environment. The total mercury concentrations ranged from 3.9 to 992.7ngL(-1) for the water samples, 40.6 to 2204.0ngg(-1) for the soil samples, 14.2 to 376.7ngg(-1) for the sediment samples, and 0.22 to 1.74ngg(-1) for the pomegranates samples. The higher values in the water samples collected from the rivers closer to and downstream of the city resulted from wastewater discharges. The effects of the mercury buried in the Qinshihuang Mausoleum thousands of years ago on the environment were neither significant nor widespread. Immediate actions should be taken to stop the direct and continuous discharges of industrial and residential wastewaters to prevent mercury and other pollutants from accumulating and spreading in the area.
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Monitoreo del Ambiente/métodos , Contaminación de Alimentos/análisis , Actividades Humanas , Mercurio/análisis , Contaminantes Atmosféricos/química , China , Ciudades , Sedimentos Geológicos/química , Humanos , Lythraceae/química , Suelo/análisis , Contaminantes del Suelo/química , Tiempo , Contaminantes Químicos del Agua/químicaRESUMEN
The mercury distribution and speciation in the water column were investigated from November 2003 to September 2004. The distribution and concentrations of total mercury (THg) and particulate mercury (PHg) showed that algae had a large capacity to bind mercury in late spring (e.g. in May). It is shown that dissolved gaseous mercury (DGM) concentrations may also be affected by algae activities. The MeHg profile in the water column at a highly eutrophied site in Hongfeng Reservoir demonstrated that most of the MeHg was produced in the hypolimnion, whereas the MeHg profile pattern at another site with less eutrophication indicated that MeHg in water was largely ascribed to release from sediment. In September, the outflow of the reservoir was enriched with MeHg, which was 5.5 times higher than that in the inflows. The discharge of MeHg-concentrated water from the anoxic hypolimnion in the reservoir may pose a risk to downstream fauna.