scholarly journals First long-term and near real-time measurement of atmospheric trace elements in Shanghai, China

2017 ◽  
Author(s):  
Yunhua Chang ◽  
Kan Huang ◽  
Congrui Deng ◽  
Zhong Zou ◽  
Shoudong Liu ◽  
...  
Keyword(s):  
Trace Elements ◽  
Fine Particles ◽  
Health Concern ◽  
Metal Species ◽  
Effective Control ◽  
Pollution Level ◽  
High Time Resolution ◽  
Long Distance ◽  
Stationary Combustion

Abstract. Atmospheric trace elements, especially metal species, are an emerging environmental and health concern with poorly constrained on its abundances and sources in Shanghai, the most important industrial megacity in China. Here we continuously performed a one-year (from March 2016 to February 2017) and hourly-resolved measurement of eighteen elements in fine particles (PM2.5) at Shanghai urban center with a Xact multi-metals monitor and several collocated instruments. Independent ICP-MS offline analysis of filter samples was used to validate the performance of Xact that was based on energy-dispersive X-ray fluorescence analysis of aerosol deposits on reactive filter tapes. Mass concentrations (mean ± 1σ; ng m-3) determined by Xact ranged from detection limits (nominally 0.1 to 20 ng m-3) to 14.7 µg m-3, with Si as the most abundant element (638.7 ± 1004.5), followed by Fe (406.2 ± 385.2), K (388.6 ± 326.4), Ca (191.5 ± 383.2), Zn (120.3 ± 131.4), Mn (31.7 ± 38.7), Pb (27.2 ± 26.1), Ba (24.2 ± 25.4), V (13.4 ± 14.5), Cu (12.0 ± 11.4), Cd (9.6 ± 3.9), As (6.6 ± 6.6), Ni (6.0 ± 5.4), Cr (4.5 ± 6.1), Ag (3.9 ± 2.6), Se (2.6 ± 2.9), Hg (2.2 ± 1.7), and Au (2.2 ± 3.4). Metal related oxidized species comprised an appreciable fraction of PM2.5 during all seasons, accounting for 8.3 % on average. As a comparison, atmospheric metal pollution level in Shanghai was comparable with other industrialized cities in East Asia but one or two orders magnitude higher than the sites in North America and Europe. Here our high time-resolution observations over long-term period also offer a unique opportunity to provide robust diurnal profiles for each species, which are useful in determining the sources and processes contributing to the fluctuation of atmospheric trace elements. Besides, various mathematical methods and physical evidences were served as criteria to constrain various solutions of source identification. Results showed that atmospheric trace elements pollution in Shanghai was the interplay of local emissions and regional transport, and different sources of metal species generally have different variation patterns associated with different source regions. Specifically, V and Ni were confirmed as the prominent and exclusive tracer of heavy oil combustion from shipping traffic. Fe and Ba were strongly related to brake wear, and exhibited significant correlation with Si and Ca, suggesting that Si and Ca in Shanghai were primarily sourced from road fugitive dust rather than long-distance dust transport and local building construction sites. Stationary combustion of coal was found to be the major source of As, Se, Pb, Cu and K, and the ratio of As / Se was used to infer that coal consumed in Shanghai likely originated from Henan coal fields in Northern China. Cr, Mn and Zn were the mixed result of emissions from stationary combustion coal, ferrous metals production, and nonferrous metals processing. Ag and Cd in Shanghai urban atmosphere were also the mixture of miscellaneous sources. Collectively, our findings in this study provide baseline data with high detail, which are needed for developing effective control strategies to reduce the high risk of acute exposure to atmospheric trace elements in China's megacities.

scholarly journals First long-term and near real-time measurement of trace elements in China's urban atmosphere: temporal variability, source apportionment and precipitation effect

2018 ◽  
Vol 18 (16) ◽  
pp. 11793-11812 ◽  
Author(s):  
Yunhua Chang ◽  
Kan Huang ◽  
Mingjie Xie ◽  
Congrui Deng ◽  
Zhong Zou ◽  
...  
Keyword(s):  
Trace Elements ◽  
Coal Combustion ◽  
Nonferrous Metal ◽  
Fine Particles ◽  
Ferrous Metal ◽  
Urban Atmosphere ◽  
Health Concern ◽  
Metal Species ◽  
Effective Control ◽  
Related Factor

Abstract. Atmospheric trace elements, especially metal species, are an emerging environmental and health concern with insufficient understanding of their levels and sources in Shanghai, the most important industrial megacity in China. Here we continuously performed a 1 year (from March 2016 to February 2017) and hourly resolved measurement of 18 elements in fine particles (PM2.5) at the Shanghai urban center with an Xact multi-metals monitor and several collocated instruments. Mass concentrations (mean ± 1σ; ng m−3) determined by Xact ranged from detection limits (nominally 0.1 to 20 ng m−3) to 15 µg m−3. Element-related oxidized species comprised an appreciable fraction of PM2.5 during all seasons, accounting for 8.3 % on average. As a comparison, the atmospheric elements concentration level in Shanghai was comparable with that in other industrialized cities in East Asia but 1 or 2 orders of magnitude higher than at sites in North America and Europe. Positive matrix factorization (PMF) was applied to identify and apportion the sources of the elements in the PM2.5 mass. Five different factors were resolved (notable elements and relative contribution in parentheses): traffic-related (Ca, Fe, Ba, Si; 46 %), shipping (V, Ni; 6 %), nonferrous metal smelting (Ag, Cd, Au; 15 %), coal combustion (As, Se, Hg, Pb; 18 %) and ferrous metal smelting (Cr, Mn, Zn; 15 %). The contribution from the exhaust and non-exhaust vehicle emissions, i.e., the traffic-related factor shows a strong bimodal diurnal profile with average concentration over 2 times higher during the rush hour than during nighttime. The shipping factor was firmly identified because V and Ni, two recognized tracers of shipping emissions, are almost exclusively transported from the East China Sea and their ratio (around 3.2) falls within the variation range of V ∕ Ni ratios in particles emitted from heavy oil combustion. Interestingly, nearly half of the K was derived from coal combustion with high mineral affinity (elements associated with aluminosilicates, carbonates and other minerals in coal ash). The contributions of nonferrous metal smelting to the trace elements are consistent with a newly developed emission inventory. Although the precipitation scavenging effect on the mass concentration of the trace elements varied among different species and sources, precipitation could effectively lower the concentration of the traffic- and coal combustion-related trace elements. Therefore, water spray to simulate natural types of precipitation could be one of the abatement strategies to facilitate the reduction of ambient PM2.5 trace elements in the urban atmosphere. Collectively, our findings in this study provide baseline levels and sources of trace elements with high detail, which are needed for developing effective control strategies to reduce the high risk of acute exposure to atmospheric trace elements in China's megacities.

scholarly journals Metal Toxicity at the Synapse: Presynaptic, Postsynaptic, and Long-Term Effects

2012 ◽  
Vol 2012 ◽  
pp. 1-42 ◽  
Author(s):  
Sanah Sadiq ◽  
Zena Ghazala ◽  
Arnab Chowdhury ◽  
Dietrich Büsselberg
Keyword(s):  
Synaptic Plasticity ◽  
Gaba Receptors ◽  
Intracellular Signaling ◽  
Health Concern ◽  
Metal Species ◽  
Long Term Effects ◽  
Metal Interactions ◽  
Intracellular Signaling Pathways ◽  
Specific Metal

Metal neurotoxicity is a global health concern. This paper summarizes the evidence for metal interactions with synaptic transmission and synaptic plasticity.Presynapticallymetal ions modulate neurotransmitter release through their interaction with synaptic vesicles, ion channels, and the metabolism of neurotransmitters (NT). Many metals (e.g., , , and ) also interact with intracellular signaling pathways.Postsynaptically, processes associated with the binding of NT to their receptors, activation of channels, and degradation of NT are altered by metals. , , , , , , , , and methylmercury modulate NMDA, AMPA/kainate, and/or GABA receptors activity. , , , and also impairsynaptic plasticityby targeting molecules such as CaM, PKC, and NOS as well as the transcription machinery involved in the maintenance of synaptic plasticity. The multiple effects of metals might occur simultaneously and are based on the specific metal species, metal concentrations, and the types of neurons involved.

CO-OCCURRING TRACE ELEMENTS (CTES) OF POTENTIAL HUMAN HEALTH CONCERN IN ARSENIC CONTAMINATED AQUIFERS IN THE BENGAL BASIN

2020 ◽  
Author(s):  
Harshad Vijay Kulkarni ◽  
◽  
Michael Vega ◽  
Karen Johannesson ◽  
Robert Taylor ◽  
...  
Keyword(s):  
Trace Elements ◽  
Human Health ◽  
Health Concern ◽  
Bengal Basin ◽  
Contaminated Aquifers ◽  
Potential Human Health

Mindtree: Tryst with the Corporate Control Market

2021 ◽  
pp. 227797792199190
Author(s):  
P. Bala Bhaskaran
Keyword(s):  
Capital Market ◽  
Corporate Control ◽  
Theory And Practice ◽  
Effective Control ◽  
Small Fish ◽  
Market Theory ◽  
Strategic Fit ◽  
Sequence Of Events ◽  
The Capital Market

The case is structured around the takeover of Mindtree Ltd (ML) by Larsen & Toubro Ltd (L&T) in June 2019. ML was founded and nurtured by a group of software professionals. In two decades, it had blossomed into an enterprise with global presence, US$ 1 billion turnover and a unique organizational culture. In a strange sequence of events, more than 20% of ML’s shares landed in L&T’s lap. L&T grabbed this opportunity and ran a systematic campaign to acquire the company. In about 100 days, L&T achieved its objective and got into the driver’s seat. The case traces the evolution of ML from a start-up to a publicly held company with global standing. It examines the circumstances and events leading to L&T getting the initial stake in the company; it examines the acquisition campaign of L&T and the response of the top management of ML. Research Questions Was there a strategic fit between ML and L&T? Were the capital market processes just and fair to all the stakeholders involved in the acquisition? Was L&T fair, prudent and sensitive in the acquisition process? Was Siddhartha loyal and fair to the founders of ML? Link to Theory The theoretical concepts that would enable a better comprehension of the case are: Analysis of strategic fit in M&A situations Capital market: Theory and practice Strategy for corporate control of an enterprise Significance of culture and ecosystem in knowledge organizations Phenomenon Studied Leadership styles relevant at different stages of evolution of an enterprise are different. A leader, at a given point of time, is successful when he is able to match his aspirations with the leadership needs of the enterprise at that point of time. The case can be used to demonstrate this phenomenon. Case Context Context of the case is that of an emerging infotech enterprise, coming under corporate raid and the unfolding capital market processes. The case highlights the shortcomings of the co-founders, leading to their unseating as also the sensitivity of the incoming management in handling the transition. Findings The case demonstrates the ability of the capital market to be fair to all stakeholders ensuring reward for competence and punishment for sloppiness. The case emphasizes the need for co-founders to have an effective strategy for corporate control; only then they could hope to achieve the long-term objectives. The case also illustrates the significance of sensitivity in handling softer issues like people and ecosystem in ensuring long-term success. Discussions At the outset, the case may appear to be that of a big fish swallowing a small fish. But a closer scrutiny would reveal the multiple dimensions of the case. Consider the role of Siddhartha. He seeded the idea of the company; he was a financier to it; he remained an investor in the company longer than most of the founders; when he pulled out, the co-founders could not hold the company together. Neither Siddhartha nor the co-founders had the far-sightedness to consolidate their shareholdings for effective control of the company into the future. This would trigger discussions on the differing roles of technocrats, managers, leaders and founders. Another point worthy of discussion would be: How were the co-founders choosing their leaders? Was it by rotation among themselves, or did they engage a set of criteria to identify an incumbent capable of leading a global company?

scholarly journals Depression following traumatic brain injury: a comprehensive overview

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Marc Fakhoury ◽  
Zaynab Shakkour ◽  
Firas Kobeissy ◽  
Nada Lawand
Keyword(s):  
Traumatic Brain Injury ◽  
Brain Injury ◽  
Health Concern ◽  
First Year ◽  
Comprehensive Overview ◽  
Symptoms Of Depression ◽  
Current State ◽  
Post Traumatic ◽  
Brain Changes

Abstract Traumatic brain injury (TBI) represents a major health concern affecting the neuropsychological health; TBI is accompanied by drastic long-term adverse complications that can influence many aspects of the life of affected individuals. A substantial number of studies have shown that mood disorders, particularly depression, are the most frequent complications encountered in individuals with TBI. Post-traumatic depression (P-TD) is present in approximately 30% of individuals with TBI, with the majority of individuals experiencing symptoms of depression during the first year following head injury. To date, the mechanisms of P-TD are far from being fully understood, and effective treatments that completely halt this condition are still lacking. The aim of this review is to outline the current state of knowledge on the prevalence and risk factors of P-TD, to discuss the accompanying brain changes at the anatomical, molecular and functional levels, and to discuss current approaches used for the treatment of P-TD.

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