The idea of single particle aerosol mass spectrometry was first proposed in the 1970s and then developed quickly in recent two decades. Because it can simultaneously provide much information including particle size distribution, composition of multiple chemical species and mixing state for each single particle with high-time resolution, single particle aerosol mass spectrometry has been widely applied in the area of environmental monitoring and fine particulate matter research. This review aims to (1) provide an introduction of the development history and progress of single particle aerosol time-of-flight mass spectrometry, (2) summarize its principle, methods for data analysis, output of results and its applications in environmental measurement and research using two major commercialized instruments (ATOFMS and SPAMS), and (3) provide suggestions for future research.
The debonding of particle/matrix interfaces has an important effect on the behavior of composite materials. During last decades, great efforts have been made to simulate the behavior of the interface. Boundary element method, as an alternative effective numerical method, has great advantages in simu...
The Chinese government has adopted Payment for Ecosystem Services (PES) as a main approach for preventing or restoring rangelands perceived as undergoing degradation on a massive scale. Using the PES project, known as the 'retire livestock, restore rangeland' project in Alxa of Inner Mongolia as an example, the long-term ecological consequences of such projects is assessed, and the causes of the associated problems from the perspective of social-ecological system explored. Study findings demonstrate that PES, as used in the case study area, is unlikely to achieve the expected outcome of rangeland restoration in the long term. The root cause of such failure is that the PES approach focuses on end-point ecosystem services (outputs), while at the same time decoupling the feedbacks among social and ecological systems that are the key to generating such services. This drives the overall social-ecological system into an undesirable basin of attraction. It is concluded that a PES program for pastoral systems should aim to improve resilience of such a coupled social-ecological system to external shocks and changes, instead of simply maintaining ecological services without considering the origins of such services in the inter-relationship of humans and environment. It is argued that 'Payment for Ecosystem Services' should be displaced by 'Payment for Social-ecological System Resilience' in future policy discussions.;The Chinese government has adopted Payment for Ecosystem Services (PES) as a main approach for preventing or restoring rangelands perceived as undergoing degradation on a massive scale. Using the PES project, known as the 'retire livestock, restore rangeland' project in Alxa of Inner Mongolia as an example, the long-term ecological consequences of such projects is assessed, and the causes of the associated problems from the perspective of social-ecological system explored. Study findings demonstrate that PES, as used in the case study area, is unlikely to achieve the expected outcome of rangeland restoration in the long term. The root cause of such failure is that the PES approach focuses on end-point ecosystem services (outputs), while at the same time decoupling the feedbacks among social and ecological systems that are the key to generating such services. This drives the overall social-ecological system into an undesirable basin of attraction. It is concluded that a PES program for pastoral systems should aim to improve resilience of such a coupled social-ecological system to external shocks and changes, instead of simply maintaining ecological services without considering the origins of such services in the inter-relationship of humans and environment. It is argued that 'Payment for Ecosystem Services' should be displaced by 'Payment for Social-ecological System Resilience' in future policy discussions. Additional keywords: Inner Mongolia, payment for ecosystem services, rangeland conservation, social-ecological system.;
In this paper, the shear-improved Smagorinsky model (SISM) is assessed in a K-type transitional channel flow. Our numerical simulation results show that the original SISM model is still too dissipative to predict the transitional channel flow. Two former reported empirical correction approaches, including a low-Reynolds-number correction and a shape-factor-based intermittency correction, are applied to further promote the capability of the SISM model in simulating the transition process. Numerical tests show that the shape-factor-based intermittency correction approach can correctly improve the transition-prediction capability of the SISM model, while the low-Reynolds-number correction approach fails. Furthermore, the shape-factor-based intermittency-corrected SISM model can capture the vortical structures during the transitional process very well and possesses the grid-insensitive characteristics.
It is not known whether exposure to air pollutants causes systemic oxidative stress in children. We investigated the association between exposure to air pollution and biomarkers of oxidative stress in relation to a governmental air quality intervention implemented during the 2008 Beijing Olympic Games. We studied 36 schoolchildren during 5 time periods before and during the Olympic Games in Beijing (June 2007-September 2008). The oxidative stress biomarkers 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) and malondialdehyde were measured in urine samples collected daily during each period. Generalized estimating equations were used to examine the relationship between repeated biomarker measurements and ambient air pollutant levels. During the Olympic intervention period, substantial reductions in air pollution (-19% to -72%), urinary 8-oxodG concentrations (-37.4%; 95% confidence interval: -53.5, -15.7), and urinary malondialdehyde concentrations (-25.3%; 95% confidence interval: -34.3, -15.1) were found. Malondialdehyde and 8-oxodG were significantly associated with concentrations of black carbon, fine particulate matter with an aerodynamic with diameter less than 2.5 mu m, sulfur dioxide, nitrogen dioxide, and carbon monoxide. Biomarker changes per each interquartile-range increase in pollutants were largest at lag 0 or lag 1. In a 2-pollutant model, the most robust associations were for black carbon. These findings suggest that exposure to black carbon leads to systemic oxidative stress in children.
STUDY QUESTION: Is polycystic ovary syndrome (PCOS) associated with increased serum levels of typical organic pollutants? summary answer: PCOS in Han females from Northern China was significantly associated with elevated serum levels of pollutants, including polychlorinated biphenyls (PCBs), organochlorine pesticides and polycyclic aromatic hydrocarbons (PAHs). what is known already: PCOS is arguably the most common endocrinopathy in females of reproductive age. The etiology of PCOS is thought to be multifactorial. study design, size, duration: This was a preliminary case-control study undertaken at the Division of Reproductive Center, Peking University Third Hospital. Fifty participants affected by PCOS and 30 normal controls were recruited between August and October 2012 from Northern China. All participants were Han women. participants/materials, setting, methods: PCOS participants were diagnosed according to the 2003 Rotterdam criteria. The control participants were non-pregnant females unable to conceive solely due to male azoospermia. Serum levels of a wide range of organic pollutants, including PCBs, organochlorine pesticides, PAHs and more than 20 phenolic pollutants, were analyzed using gas chromatographic mass spectrometry. main results and the role of chance: Serum levels of PCBs, pesticides and PAHs were significantly higher in the PCOS group than the control group. Concentrations of PCBs, p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE) and PAHs in serum above median levels were associated with PCOS with odds ratios of 3.81 [95% confidence interval (CI), 1.45-10.0], 4.89 (95% CI, 1.81-13.2) and 2.39 (95% CI, 0.94-6.05), respectively. Partial least-squares-discriminant analysis (PLS-DA) confirmed that serum levels of organic pollutants were associated with PCOS, especially for p, p'-DDE and PCBs. limitations, reasons for caution: Some other possible covariates (e.g. dietary and income) were missed in this study, although education and occupation have been considered as an indicator of personal income. The PLS-DA model allowed a quasi-exposome analysis with over 60 kinds of typical organic pollutants; however, the possibility of other pollutants involved in the PCOS still could not be excluded. wider implications of the findings: Our study identified that bodily retention of environmental organic pollutants-including PCBs, pesticides (especially p, p'-DDE) and PAHs-was associated with PCOS.
Barbecuing or charcoal-grilling has become part of popular outdoor recreational activities nowadays; however, potential human health hazards through outdoor exposure to barbecue fumes have yet to be adequately quantified. To fill this knowledge gap, atmospheric size-fractioned particle and gaseous samples were collected near an outdoor barbecuing vendor stall (along with charcoal-grilled food items) in Xinjiang of Northwest China with a 10-stage micro-orifice uniform deposit impactor and a polyurethane foam (PUP) sampler and were analyzed for particulate matter and polycyclic aromatic hydrocarbons (PAHs). Exposure to PAHs through inhalation and dermal contact by adult consumers who spent 1 h per day near a charcoal-grilling vendor for a normal meal (lunch or dinner) amounted to a BaP equivalent (BaPeq) dosage of 3.0-77 ng day(-1) (inhalation: 2.8-27 ng day(-1) of BaPeq; dermal contact: 0.2-50 ng day(-1) of BaPeq), comparable to those (22-220 ng day(-1) of BaPeq) from consumer exposure through the consumption of charcoal-grilled meat, assumed to be at the upper limit of 50-150 g. In addition, the potential health risk was in the range of 3.1 X 10(-10) to 1.4 X 10(-4) for people of different age groups with inhalation and dermal contact exposure to PAHs once a day, with a 95% confidence interval (7.2 X 10(-9) to 1.2 X 10(-6)) comparable to the lower limit of the potential cancer risk range (1 X 10(-6) to 1 X 10(-4)). Sensitivity analyses indicated that the area of dermal contact with gaseous contaminants is a critical parameter for risk assessment. These results indicated that outdoor exposure to barbecue fumes (particularly dermal contact) may have become a significant but largely neglected source of health hazards to the general population and should be well-recognized.
The stress and the debonding of the interface in coating layers structure due to thermal loading are investigated by using boundary element methods(BEM). The nearly-singular integrals that arise in the boundary integral equation(BIE) for such thin layered structures cannot be accurately evaluated us...
PCN bacteria capable of heterotrophic-aerobic nitrogen removal was successfully applied for bioaugmented treatment of municipal wastewater in a pilot-scale SBR. At an appropriate COD/N ratio of 8, the bioaugmentation system exhibited stable and excellent carbon and nutrients removal, the averaged effluent concentrations of COD, NH4+-N, TN and TP were 20.6, 0.69, 14.1 and 0.40 mg/L, respectively, which could meet the first class requirement of the National Municipal Wastewater Discharge Standards of China (COD < 50 mg/L, TN < 15 mg/L, TP < 0.5 mg/L). Clone library and real-time PCR analysis revealed that the introduced bacteria greatly improved the structure of original microbial community and facilitated their aerobic nutrients removal capacities. The proposed emerging technology was shown to be an alternative technology to establish new wastewater treatment systems and upgrade or retrofit conventional systems from secondary-level to tertiary-level. (C) 2015 Elsevier Ltd. All rights reserved.