Sveite from the Northeastern San Joaquin Valley, California

ABSTRACT Sveite [KAl7(NO3)4(OH)16Cl2·8H2O] first described from Venezuela and material recently collected from northern California have similar X-ray diffraction patterns and chemical compositions. The main difference in the chemical composition is the absence of significant chlorine and sulfate in the sveite from California. The changes observed by X-ray diffraction upon hydration and the SEM images of the crystals suggest a layered atomic structure. Water-extractable NO3 in the Venezuelan sveite sample is isotopically enriched in δ15N and δ18O and likely was affected by the microbial process of denitrification. In contrast, the extractable nitrate from the California sveite is less isotopically enriched than the Venezuelan mineral and there is only modest evidence that denitrification had affected its isotopic composition. Overall, the nitrate in the California sveite is isotopically similar to nitrate present in acidic soils overlying the mineral occurrence, suggesting a general biogenic source of uric acid from bird feces for the mineral-bound nitrogen.

Seasonal variation and origins of volatile organic compounds observed during 2 years at a western Mediterranean remote background site (Ersa, Cape Corsica)

An original time series of about 300 atmospheric measurements of a wide range of volatile organic compounds (VOCs) was obtained at a remote Mediterranean station on the northern tip of Corsica (Ersa, France) over 25 months from June 2012 to June 2014. This study presents the seasonal variabilities of 35 selected VOCs and their various associated sources. The VOC abundance was largely dominated by oxygenated VOCs (OVOCs) along with primary anthropogenic VOCs with a long lifetime in the atmosphere. VOC temporal variations were then examined. Primarily of local origin, biogenic VOCs exhibited notable seasonal and interannual variations, related to temperature and solar radiation. Anthropogenic compounds showed increased concentrations in winter (JFM months) followed by a decrease in spring/summer (AMJ/JAS months) and higher winter concentration levels in 2013 than in 2014 by up to 0.3 µg m−3 in the cases of propane, acetylene and benzene. OVOC concentrations were generally high in summertime, mainly due to secondary anthropogenic/biogenic and primary biogenic sources, whereas their lower concentrations during autumn and winter were potentially more influenced by primary/secondary anthropogenic sources. Moreover, an apportionment factorial analysis was applied to a database comprising a selection of 14 individual or grouped VOCs by means of the positive matrix factorization (PMF) technique. A PMF five-factor solution was taken on. It includes an anthropogenic factor (which contributed 39 % to the total concentration of the VOCs selected in the PMF analysis) connected to the regional background pollution, three other anthropogenic factors (namely short-lived anthropogenic sources, evaporative sources, and long-lived combustion sources, which together accounted for 57 %) originating from either nearby or more distant emission areas (such as Italy and south of France), and a local biogenic source (4 %). Variations in these main sources impacting VOC concentrations observed at the Ersa station were also investigated at seasonal and interannual scales. In spring and summer, VOC concentrations observed at Ersa were the lowest in the 2-year period, despite higher biogenic source contributions. During these seasons, anthropogenic sources advected to Ersa were largely influenced by chemical transformations and vertical dispersion phenomena and were mainly of regional origins. During autumn and winter, anthropogenic sources showed higher contributions when European air masses were advected to Ersa and could be associated with potential emission areas located in Italy and possibly more distant ones in central Europe. Higher VOC winter concentrations in 2013 than in 2014 could be related to contribution variations in anthropogenic sources probably governed by their emission strength with external parameters, i.e. weaker dispersion phenomena and the pollutant depletion. High-frequency observations collected during several intensive field campaigns conducted at Ersa during the three summers 2012–2014 confirmed findings drawn from bi-weekly samples of the 2-year period in terms of summer concentration levels and source apportionment. However, they also suggested that higher sampling frequency and temporal resolution, in particular to observe VOC concentration variations during the daily cycle, would have been necessary to confirm the deconvolution of the different anthropogenic sources identified following the PMF approach. Finally, comparisons of the 25 months of Ersa observations with VOC measurements conducted at 17 other European monitoring stations highlighted the representativeness of the Ersa station for monitoring seasonal variations in VOC regional pollution impacting continental Europe. Nevertheless, VOC winter concentration levels can significantly vary between sites, pointing out spatial variations in anthropogenic source contributions. As a result, Ersa concentration variations in winter were more representative of VOC regional pollution impacting central Europe. Moreover, interannual and spatial variations in VOC winter concentration levels were significantly impacted by synoptic phenomena influencing meteorological conditions observed in continental Europe, suggesting that short observation periods may reflect the variability of the identified parameters under the specific meteorological conditions of the study period.

Phosphine in Venus’ atmosphere: Detection attempts and upper limits above the cloud top assessed from the SOIR/VEx spectra

Context. Recent detection of phosphine (PH3) was reported from James Clerk Maxwell Telescope and Atacama Large Millimetre/submillimetre Array observations. The presence of PH3 on Venus cannot be easily explained in the Venus atmosphere and a biogenic source located at or within the clouds was proposed. Aims. We aim to verify if the infrared spectral signature of PH3 is present in the spectra of Solar Occultation at Infrared (SOIR). If it is not present, we then seek to derive the upper limits of PH3 from SOIR spectra. Methods. We analyzed the SOIR spectra containing absorption lines of PH3. We searched for the presence of PH3 lines. If we did not find any conclusive PH3 spectral signatures, we computed the upper limits of PH3. Results. We report no detection of PH3. Upper limits could be determined for all of the observations, providing strong constraints on the vertical profile of PH3 above the clouds. Conclusions. The SOIR PH3 upper limits are almost two orders of magnitude below the announced detection of 20 ppb and provide the lowest known upper limits for PH3 in the atmosphere of Venus.

Biomaterial for Bone and Dental Implants: Synthesis of B-Type Carbonated Hydroxyapatite from Biogenic Source

There are several sources from which hydroxyapatite (HAp) can be obtained and may be broadly categorized as synthetic or biogenic. Elevated interest in recent times has pushed for the development of several procedures for extracting HAp from biogenic wastes due to their excellent composition and morphology resemblance to the human calcified tissue (B-type carbonated HAp). Notable biogenic sources reported for HAp extraction span bovine bones, fish scales, corals, eggshells, and snails among other calcium-rich sources. However, most of the synthetic methods are laborious and therefore result in high production costs. In this chapter, we discuss the synthesis of B-type carbonate substituted HAp from an untapped biogenic source, Achatina achatina shells, using a simple precipitation method and a controlled heat-treatment method. This unique treatment method affected the substitution resulting in different crystallographic parameters and revealed a novel material for bone implants and enamel applications.

Source Apportionment of PM2.5 in Guangzhou Based on an Approach of Combining Positive Matrix Factorization with the Bayesian Mixing Model and Radiocarbon

To accurately apportion the sources of aerosols, a combined method of positive matrix factorization (PMF) and the Bayesian mixing model was applied in this study. The PMF model was conducted to identify the sources of PM2.5 in Guangzhou. The secondary inorganic aerosol source was one of the seven main sources in Guangzhou. Based on stable isotopes of oxygen and nitrogen (δ15N-NO3− and δ18O-NO3−), the Bayesian mixing model was performed to apportion the source of NO3− to coal combustion, traffic emission and biogenic source. Then the secondary aerosol source was subdivided into three sources according to the discrepancy in source apportionment of NO3− between PMF and Bayesian mixing model results. After secondary aerosol assignment, the six main sources of PM2.5 were traffic emission (30.6%), biomass burning (23.1%), coal combustion (17.7%), ship emission (14.0%), biomass boiler (9.9%) and industrial emission (4.7%). To assess the source apportionment results, fossil/non-fossil source contributions to organic carbon (OC) and element carbon (EC) inferred from 14C measurements were compared with the corresponding results in the PMF model. The results showed that source distributions of EC matched well between those two methods, indicating that the PMF model captured the primary sources well. Probably because of the lack of organic molecular markers to identify the biogenic source of OC, the non-fossil source contribution to OC in PMF results was obviously lower than 14C results. Thus, an indicative organic molecular tracer should be used to identify the biogenic source when accurately apportioning the sources of aerosols, especially in the region with high plant coverage or intense biomass burning.

Seasonal Changes in Microbial Dissolved Organic Sulfur Transformations in Coastal Waters

The marine trace gas dimethylsulfide (DMS) is the single most important biogenic source of atmospheric sulfur, accounting for up to 80% of global biogenic sulfur emissions. Approximately 300 million tons of DMS are produced annually, but the majority is degraded by microbes in seawater. The DMS precursor dimethylsulfoniopropionate (DMSP) and oxidation product dimethylsulphoxide (DMSO) are also important organic sulfur reservoirs. However, the marine sinks of dissolved DMSO remain unknown. We used a novel combination of stable and radiotracers to determine seasonal changes in multiple dissolved organic sulfur transformation rates to ascertain whether microbial uptake of dissolved DMSO was a significant loss pathway. Surface concentrations of DMS ranged from 0.5 to 17.0 nM with biological consumption rates between 2.4 and 40.8 nM·d−1. DMS produced from the reduction of DMSO was not a significant process. Surface concentrations of total DMSO ranged from 2.3 to 102 nM with biological consumption of dissolved DMSO between 2.9 and 111 nM·d−1. Comparisons between 14C2-DMSO assimilation and dissimilation rates suggest that the majority of dissolved DMSO was respired (>94%). Radiotracer microbial consumption rates suggest that dissimilation of dissolved DMSO to CO2 can be a significant loss pathway in coastal waters, illustrating the significance of bacteria in controlling organic sulfur seawater concentrations.

Characteristics and sources of aerosol aminiums over the eastern coast of China: insights from the integrated observations in a coastal city, adjacent island and surrounding marginal seas

An integrated observation of aerosol aminiums was conducted in a coastal city (Shanghai) in eastern China, a nearby island (Huaniao Island), and over the Yellow Sea and East China Sea (YECS). Triethylaminium (TEAH+) was abundant over Shanghai but not detected over the island and the open seas, suggesting its predominantly terrestrial origin. By contrast, relatively high concentrations of dimethylaminium (DMAH+) and trimethylaminium + diethylaminium (TMDEAH+) were measured over the ocean sites, indicating the significant marine source contribution. Environmental factors, including boundary layer height (BLH), temperature, atmospheric oxidizing capacity and relative humidity, were found to be related to aminium concentrations. All the detected aminiums demonstrated the highest levels in winter in Shanghai, consistent with the lowest BLH and temperature in this season. Aminiums mainly existed in fine particles and showed a bimodal distribution, with two peaks at 0.18–0.32 µm and 0.56–1.0 µm, indicating that condensation and cloud processing were the main formation pathways for aminiums in analogy with NH4+ and non-sea-salt SO42- (nss-SO42-). Nonetheless, a unimodal distribution for aerosol aminiums was usually measured over the YECS or over Huaniao Island when influenced mainly by the marine air mass, which suggested that aminiums in marine aerosols may undergo different formation pathways from those on the land. Terrestrial anthropogenic sources and marine biogenic sources were both important contributors for DMAH+ and TMDEAH+, and the latter exhibited a significantly higher TMDEAH+ to DMAH+ ratio. By using the mass ratio of methanesulfonate (MSA) to nss-SO42- as an indicator of marine biogenic source, we estimated that marine biogenic source contributed to 26 %–31 % and 53 %–78 % of aerosol aminiums over Huaniao Island in the autumn of 2016 and summer of 2017, respectively. Due to the important role of atmospheric amines in new particle formation, the estimation results highlighted the importance of marine biogenic emission of amines on the eastern coast of China, especially in summer.