Molecular level characterization of dissolved organic sulfur (DOS) by electrospray ionization-Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR MS) is necessary for further understanding of the role of DOS in the environment. Here, ESI spray solvent, a key parameter for ion production during ESI process, was investigated for its effect on the molecular characterization of DOS by ESI-FTICR MS. 100% MeOH as spray solvent was found for the first time to remarkably enhance the ionization efficiency of the majority of CHOS-molecules in NOM, which facilitated a total of 1473 CHOS-molecular formulas with one sulfur atom to be detected. The number of CHOS-molecular formulas obtained using 100%MeOH as spray solvent increased notably over 740 in comparison with those using 50% MeOH aqueous solution (731) or 50% ACN aqueous solution (653). Moreover, due to the enhancement of ionization efficiency of DOS during ESI processes, the tandem mass spectra of the NOM CHOS-molecules could be easily obtained using 100% MeOH as spray solvent, which were hardly obtained using 50% MeOH aqueous solution as spray solvent. The results of the tandem mass spectra suggested the first discovery of organosulfates or sulfonic acids in Suwannee River NOM sample. A simple method based on 100% MeOH as ESI spray solvent for advanced molecular characterization of DOS by ESI-FTICR MS was proposed and applied, and the results revealed more molecular information of DOS in sea DOM samples. 相似文献
Eighteen polycyclic aromatic hydrocarbons (PAHs) were detected in benthos collected onboard the ‘Snow Dragon’ in the Northern Bering Sea Shelf and Chukchi Sea Shelf during the 6th Chinese National Arctic Research Expedition (CHINARE 2014). Σ18PAHs for all biota samples ranged from 34.2 to 128.1 ng/g dry weight (dw), with the highest concentration observed in fish muscle (Boreogadus saida) samples close to St. Lawrence Island. The PAH composition pattern was dominated by the presence of lighter 3 ring (57%) and 2 ring (28%) PAHs, indicating oil-related or petrogenic sources as important origins of PAH contamination. Concentrations of alkyl-PAHs (1-methylnaphthalene and 2-methylnaphthalene) were lower than their parent PAH (naphthalene) in all biological tissue, and their percentage also decreased significantly (p<0.05) compared with those in the corresponding sediment. There were no significant relationships between PAH concentrations and trophic levels, which is possibly due to the combined results of the complex benthic foodweb in the subarctic/Arctic shelf region, as well as a low assimilation/effective metabolism for PAHs. According to toxic potency evaluation results from TCDD toxic equivalents (TEQs) and BaP-equivalent (BaPE) values, whelk (Neptunea heros) and starfish (Ctenodiscus crispatus) are two macroinvertebrate species showing relatively higher dioxin-like toxicity and carcinogenic risk. 相似文献
Mitigation and Adaptation Strategies for Global Change - Electric vehicles (EVs) play a crucial role in addressing climate change and urban air quality concerns. China has emerged as the global... 相似文献
Both China’s national subsidy policies for plug-in electric vehicles (PEVs) purchasers and passenger cars corporate average fuel consumption and new vehicle credit regulation (dual-credit policy) favor long-range 300+ km battery electric vehicles (BEVs) and 80+ km plug-in hybrid electric vehicles (PHEVs). However, these electric vehicles tend to have lower energy efficiency and higher purchase and operation costs. Vehicle with larger batteries can also be less equitable because the subsidies are often provided to more expensive vehicles and wealthier owners. This study takes advantage of a novel dataset of daily driving data from 39,854 conventional gasoline vehicles in Beijing and 4999 PHEVs in Shanghai to determine the optimal range of BEVs and PHEVs within their respective cities. We simulate a model to explore ranges with which PEVs emit less GHGs than that of a baseline hybrid and conventional gasoline vehicle while ensuring that all daily travel demands are met. Our findings indicate that in both cities, the optimal ranges to balance cost and travel demand for BEVs are 350 km or less and for PHEVs are 60 km or less in Beijing and 80 km or less in Shanghai. We also find that to minimize carbon dioxide (CO2) emissions, the ranges are even lower 10 km in Beijing and 30 km in Shanghai. Our study suggests that instead of encouraging long-range PEVs, governments should subsidize PEV models with shorter ranges. Parallel efforts should also be made to both increase renewable energy over fossil fuels and expand charging facilities. Although individual mobility demand varies, the government could reduce occasional long-distance driving by subsidizing alternative transportation choices. Providing week-long driving trials to consumers before their purchases may help decrease the demand of very long range PEVs by alleviating the range anxiety through a learning process.
Mitigation and Adaptation Strategies for Global Change - Considering government and market failure of environmental regulation to combat increasing GHG (greenhouse gas) emissions, green innovation... 相似文献