Cd-MOF: specific adsorption selectivity for linear alkyne (propyne, 2-butyne and phenylacetylene) molecules.

The selective adsorption of APPT-Cd-MOF 1 for propyne, 2-butyne and phenylacetylene was confirmed by single-crystal analysis. In addition, the selective adsorption performance of Cd-MOF for C3H4/C3H6/C3H8 was investigated. The matching of the functionality and size/shape between porous materials and guest molecules clarified the specific recognition of 1 for linear alkyne molecules.

Distribution and sources of particulate mercury and other trace elements in PM2.5 and PM10 atop Mount Tai, China.

The concentrations of particulate mercury (PHg) and other trace elements in PM2.5 and PM10 in the atmosphere were measured at the summit of Mount Tai during the time period of 15 June - 11 August 2015. The average PHg concentrations were 83.33 ±â€¯119.1 pg/m3 for PM2.5 and 174.92 ±â€¯210.5 pg/m3 for PM10. Average concentrations for other trace elements, including Al, Ca, Fe, K, Mg, Na, Pb, As, Se, Cu, Cd, Cr, V, Mo, Co, Ag, Ba, Mn, Zn and Ni ranged from 0.06 ng/m3 (Ag) to 354.33 ng/m3 (Ca) in PM2.5 and 0.11 ng/m3 (Co) to 592.66 ng/m3 (Ca) in PM10. The average concentrations of PHg were higher than those at other domestic mountain sites and cities in other counties, lower than those at domestic city sites. Other trace elements showed concentrations lower than those at the domestic mountain sites. Due possibly to increased control of emissions and the proportion of new energy, the PHg and trace element concentrations decreased, but the PHg showed concentrations higher than those at the Mountain sites, this showed that the reasons was not only severely affected by anthropogenic emissions, but also associated with other sources. The concentration changed trend of the main trace elements indicated that PHg, trace elements and particle matters present positive correlation and fine particulate matter has a greater surface area which was conductive to adsorption of Hg and trace elements to particles. On June 19, June 27 and July 6, according to the peak of mercury and trace elements, we can predict the potential sources of these three days. The results of principal component analysis (PCA) suggested that, crustal dust, coal combustion, and vehicle emissions were the main emission sources of PHg and other trace elements in Mount Tai. The 24-h backward trajectories and potential source contribution function (PSCF) analysis revealed that air masses arriving at Mount Tai were mainly affected by Shandong province. Mount Tai was subjected to five main airflow trajectories. Clusters 1, 2, 3, and 5 represented four pathways for local and regional sources and cluster 4 originated long-distance transportation. Central Shandong was the main source regions of PHg, Pb, Se, As, Cu and Cd. Southeastern and northwestern Shandong province and northern Jiangsu province were the most polluted source regions of Mn, Zn, and Ni. The crustal elements Fe and Ca had similar distributions of potential source regions, suggested by the highest PSCF values in southeastern Shandong and northern Jiangsu.

Evaluation of the behavior of clouds in a region of severe acid rain pollution in southern China: species, complexes, and variations.

Cloud samples were collected during the summer of 2011 and the spring of 2012 at a high-elevation site in southern China in an effort to examine the chemical characteristics of acid clouds. In total, 141 cloud samples were collected during 44 cloud events over the observation period. The dominant ionic species were SO4(2-), NH4(+), and NO3(-), contributing approximately 75% of the total inorganic ion concentration. The primary acidifying factors were sulfate and nitrate, and the primary neutralizing factors were ammonium and calcium. The volume-weighted mean (VWM) pH of the cloud water was 3.79, indicating an acidic nature. In these cloud samples, Zn and Al exhibited the highest trace metal concentrations, contributing approximately 60% of the total trace element concentration. Toxic metals, such as Pb, Ba, As, and Cr, were detected at high concentrations, indicating potential hazards for human health, vegetation, and waters in this region. Visual MINTEQ 3.0 results revealed that the majority of Zn(II) and Pb(II) existed in the form of free ions. The behavior of Al, however, differed from the behaviors of zinc and lead. The temporal variation in cloud chemistry indicated that temperature, sandstorms, and long-range transport could affect the concentrations of species. During the lifetime of a cloud event, the concentrations of the chemical species were controlled by the transfer of gases or particles to liquid droplets.

Origin and distribution of trace elements in high-elevation precipitation in southern China.

INTRODUCTION: During a 2009 investigation of the transport and deposition of trace elements in southern China, 37 event-based precipitation samples were collected at an observatory on Mount Heng, China (1,269 m asl). METHODS: Concentrations of trace elements were analyzed using inductively coupled plasma-mass spectrometry and the wet deposition fluxes were established. A combination of techniques including enrichment factor analysis, principal component analysis, and back trajectory models were used to identify pollutant sources. RESULTS: Trace element concentrations at Mount Heng were among the highest with respect to measured values reported elsewhere. All elements were of non-marine origin. The elements Pb, As, Cu, Se, and Cd were anthropogenic, while Fe, Cr, V, Ba, Mn, and Ni were of mixed crustal/anthropogenic origin. The crustal and anthropogenic contributions of trace elements were 12.8 % (0.9 ~ 17.4 %) and 87.2 % (82.6 ~ 99.1 %), with the maximum crustal fraction being 17.4 % for Fe. Coal combustion, soil and road dust, metallurgical processes, and industrial activities contributed to the element composition. CONCLUSIONS: Summit precipitation events were primarily distant in origin. Medium- to long-range transport of trace elements from the Yangtze River Delta and northern China played an important role in wet deposition at Mount Heng, while air masses from south or southeast of the station were generally low in trace element concentrations.

[Spatial variations of heavy metals in precipitation at Mount Taishan region].

Zn, Al, Mn, Fe, Pb, Cu, Ni, Cr, As, Cd in rain samples collected from two sites at Mount Taishan region were determined by ICP-MS, to evaluate the spatial variation characteristics of heavy metals in precipitation. Individual rain events were sampled for one whole year from Jan. to Dec. 2006. High concentrations of heavy metals were found at both sites, indicating serious heavy metal pollution. Zn was the most abundant element, accounting for 54% - 57% of the total metals concentrations. Its volume-weighted mean concentrations of precipitation at Mt-top and Mt-foot sites were 92.94 microg/L and 70.41 microg/L respectively. The following elements were Fe, Al and Mn and their concentrations were much higher than toxic heavy metals (As, Cd and Cd) except Pb (8.04 microg/L and 7.79 microg/L at two sites respectively). Comparison results between two sites suggested that heavy metal characteristics of precipitation at two sites were different, due to the influences of different ambient air conditions. Correlation analysis between two sites showed that Al, Mn, Fe, As, Cd, Pb influenced by air mass origin greatly, while Ni, Cu, Zn affected by other different factors.

Rapid and sensitive spectrofluorimetric determination of trace amount of Cr(III) with o-vanillin-8-aminoquinoline.

A novel fluorescent reagent o-vanillin-8-aminoquinoline(OVAQ) was synthesized, and its infrared spectrum, elemental analysis and acid-base dissociation constants were obtained. The fluorescent reaction of this reagent with Cr(III) was studied. In acetonitrile-water (1:1, (v/v)) medium of pH 6.00, Cr(III) could react with fluorescent reagent OVAQ (lambda(ex/em)=280/314nm) to form a 1:1 non-fluorescent complex. The linear range of the spectrofluorimetric method proposed was from 8.2 to 130mugl(-1), and the detection limit was 2.5mugl(-1). The interferences of 25 foreign ions were also studied. This method could be easily performed and was successfully applied to the determination of Cr(III) and total chromium in domestic and industrial waste water samples.