Indoor air particles in research vessel from Shanghai to Antarctic: Characteristics, influencing factors, and potential controlling pathway.

Despite millions of seafarers and passengers staying on ships each year, few studies have been conducted on the indoor air quality inside ship hulls. In this study, we investigated the levels and size distribution of indoor particulate matter during two cruises of the research vessel "Xuelong" from Shanghai to Antarctica. The results showed that the particle size less than 2.5 µm (PM2.5), and particle size less than 10 µm (PM10) concentrations in different rooms of the ship widely varied. We observed high particulate matter (PM) levels in some of the rooms. The mass concentration distribution was dominated by 1-4 µm particles, which may have been caused by the hygroscopic growth of fine particles. The dominant factors influencing PM concentrations were indoor temperature, relative humidity, and human activity. We quantified contributions of these factors to the levels of indoor particles using a generalized additive model. In clean rooms, the levels of indoor particles were controlled by temperature and relative humidity, whereas in polluted rooms, the levels of indoor particles were mainly influenced by temperature and human activity, which implied that controlling temperature and human activity would efficiently reduce the levels of indoor particles.

Dietary T-2 toxin induces transcriptomic changes in hepatopancreas of Chinese mitten crab (Eriocheir sinensis) via nutrition metabolism and apoptosis-related pathways.

Long-term feed route exposure to T-2 toxin was proved to elicit growth retarding effects and induction of oxidative stress and apoptosis in Chinese mitten crab (Eriocheir sinensis). However, no study with a holistic perspective has been conducted to date to further describe the in-depth toxicological mechanism of T-2 toxin in E.sinensis. In this study, an RNA-Sequencing (RNA-seq) was used in this study to investigate the effects of feed supplementation with 0 mg/kg and 4 mg/kg T-2 toxin on the hepatopancreas transcriptome of E.sinensis and establish a hepatopancreas transcriptome library of T-2 toxin chronically exposed crabs after five weeks, where 14 differentially expressed genes (DEGs) were screened out across antioxidant, apoptosis, autophagy, glucolipid metabolism and protein synthesis. The actual expression of all the DEGs (Caspase, ATG4, PERK, ACSL, CAT, BIRC2, HADHA, HADHB, ACOX, PFK, eEFe1, eIF4ɑ, RPL13Ae) was also analyzed by real-time quantitative PCR (RT-qPCR). It was demonstrated that long-term intake of large amounts of T-2 toxin could impair antioxidant enzyme activity, promote apoptosis and protective autophagy, disrupt lipid metabolism and inhibit protein synthesis in the hepatopancreas of E.sinensis. In conclusion, this study explored the toxicity mechanism of T-2 toxin on the hepatopancreas of E.sinensis at the mRNA level, which lays the foundation for further investigation of the molecular toxicity mechanism of T-2 toxin in aquatic crustaceans.

Mixing state and distribution of iodine-containing particles in Arctic Ocean during summertime.

Iodine chemistry plays a key role in ozone destruction and new aerosol formation in the marine boundary layer (MBL), especially in polar regions. We investigated iodine-containing particles (0.2-2 µm) in the Arctic Ocean using a ship-based single particle aerosol mass spectrometer from July to August 2017. Seven main particle types were identified: dust, biomass combustion particles, sea salt, organic S, aromatics, hydrocarbon-like compounds, and amines. The number fraction of iodine-containing particles was higher inside the Arctic Circle (>65°N) than outside (55-65°N). According to the air mass back trajectories, the latitudinal distribution of iodine-containing particles can be mainly attributed to iodine emissions from the sea ice edge region. Diurnal trends were found, especially during the second half of cruise, with peak iodine-containing particle number fractions during low-light conditions and relatively low number fractions at midday. These results imply that solar radiation plays a significant role in modulating particulate iodine in the Arctic atmosphere.

Acute exposure to microcystin-LR induces hepatopancreas toxicity in the Chinese mitten crab (Eriocheir sinensis).

The Chinese mitten crab is an important economic species in the Chinese aquaculture industry due to its rich nutritional value and distinct flavor. The hepatopancreas is a popular edible part of the Chinese mitten crab, and therefore, hepatopancreatic health directly determines its quality. However, a large-scale outbreak of hepatopancreatic necrosis syndrome ("Shuibiezi" disease in Chinese), which is caused by abiotic agents correlated with cyanobacteria bloom outbreaks, adversely affects the Chinese mitten crab breeding industry. Cyanobacterial blooms that occur in high-density farming ponds can produce microcystin-LR (MC-LR), which is hepatotoxic in fish and mammals. Hepatopancreas toxicity of MC-LR (0, 25, 50 and 75 µg/kg) was investigated after 48 h of exposure. The MC-LR can cause hepatopancreatic injury by inducing hepatopancreatic structural damage, subcellular structural changes, and cell apoptosis, followed by enhanced lipid peroxidase, reactive oxygen species, and apoptosis-related enzyme (Caspase 3, 8, and 9) activities. These in turn promote gene and protein expression of apoptosis-associated proteases (Caspase 3, 7, and 8, Bcl-2, and Bax), and alter antioxidant system responses (superoxide dismutase, glutathione S-transferase, glutathione peroxidase, glutathione reductase activities, and glutathione content). The present study is the first report on MC-LR hepatotoxicity in the Chinese mitten crab and confirms hepatopancreas toxicity, providing a theoretical basis for enhancing MCs resistance and developing preventive and curative measures against hepatopancreatic disease in the Chinese mitten crab breeding industry.

Detection of organosulfates and nitrooxy-organosulfates in Arctic and Antarctic atmospheric aerosols, using ultra-high resolution FT-ICR mass spectrometry.

Organosulfates (OSs) are recognized as important secondary organic aerosols (SOAs) in recent years. Due to their amphipathy and light absorptive capacity, OSs may potentially impact climate. Moreover, OSs can serve as molecular tracers for precursors and multiple processes leading to the generation of SOA. However, studies on OSs are lacking in the polar regions which limits our understanding of both their formation pathways and impacts on the polar environment. Here we present the first investigation into OSs in both the Arctic and Antarctic. Organic compounds in aerosol samples collected from the polar regions during the 2013/2014 Chinese National Arctic/Antarctic Research Expedition (CHINARE) were analyzed by Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) coupled with negative ion mode electrospray ionization (ESI(-)). Hundreds to thousands of OSs were detected at the polar sampling sites. The estimated total concentrations of OSs were in the range of 46-670 ng/m3 in the Arctic sampling area, and 47-260 ng/m3 in the Antarctic sampling area, accounting for 1-16% of total OM. OSs were found to have undergone a high degree of oxidation in the aerosol samples, which might be due to the combined effects of enhanced photo-oxidation in summertime or continuous oxidation during transport to the polar region. The potential appointment of OS precursors highlights the important role of long-range air-mass transport on the OSs derived from biogenic precursors and a notably large contribution from anthropogenic emissions, suggesting that human activities have significant impacts in remote polar environments. The results of this study provide important insights into the characteristics of OSs in the polar atmosphere. However, the need for further research focusing on the quantification, formation mechanisms and impacts of OSs on climate is emphasized.

Airborne bacterial community diversity, source and function along the Antarctic Coast.

Antarctica is an isolated and relatively simple ecosystem dominated by microorganisms, providing a rare opportunity to study the spread of airborne microbes and to predict future global climate change. However, little is known about on the diversity and potential sources of microorganisms in the marine atmosphere along the Antarctica coast. Here we explored the airborne bacterial community (i.e., bacteriome) diversity, sources and functional potential along the Antarctic coast based on 16S rRNA gene amplicon sequencing of 25 bioaerosol samples collected during the 33rd Xuelong Antarctic scientific expedition. The results showed that bacterial communities in the Antarctic bioaerosols i) were predominated by Proteobacteria (91.3%) including Sphingomonas, ii) showed relative low alpha-diversity but high spatiotemporal variabilities; and iii) were potentially immigrated with terrestrial, marine and Antarctic polar bacteria through long-range transport and sea-air exchange pathways. Moreover, canonical correspondence analysis of bacteriome composition showed that wind speed, temperature, and organic carbon had a significant effect on the bacterial community (P < 0.05), although bacterial richness (Richness index) and diversity (Simpson index and Shannon index) showed no statistically significant differences between rainy, cloudy and snowy weather conditions (Adjust P > 0.05, ANOVA, Tukey HSD test). iv) The functional profiles predicted by Tax4fun2 suggest high representation of function genes related to fatty acid biosynthesis and metabolism, amino acid metabolism, nucleotide metabolism, and carbohydrate metabolism, which is conducive to the formation of microlayers on the surface of the ocean and the survival and growth of bacteria.

The observation of isotopic compositions of atmospheric nitrate in Shanghai China and its implication for reactive nitrogen chemistry.

The occurrence of PM2.5 pollution in China is usually associated with the formation of atmospheric nitrate, the oxidation product of nitrogen oxides (NOX = NO + NO2). The oxygen-17 excess of nitrate (Δ17O(NO3-)) can be used to reveal the relative importance of nitrate formation pathways and get more insight into reactive nitrogen chemistry. Here we present the observation of isotopic composition of atmospheric nitrate (Δ17O and δ15N) collected from January to June 2016 in Shanghai China. Concentrations of atmospheric nitrate ranged from 1.4 to 24.1 µg m-3 with the mean values being (7.6 ± 4.4 (1SD)), (10.2 ± 5.8) and (4.1 ± 2.4) µg m-3 in winter, spring and summer respectively. Δ17O(NO3-) varied from 20.5‰ to 31.9‰ with the mean value being (26.9 ± 2.8) ‰ in winter, followed by (26.6 ± 1.7) ‰ in spring and the lowest (23.2 ± 1.6) ‰ in summer. Δ17O(NO3-)-constrained estimates suggest that the conversion of NOX to nitrate is dominated by NO2 + OH and/or NO2 + H2O, with the mean possible contribution of 55-77% in total and even higher (84-92%) in summer. A diurnal variation of Δ17O(NO3-) featured by high values at daytime (28.6 ± 1.2‰) and low values (25.4 ± 2.8‰) at nighttime was observed during our diurnal sampling period. This trend is related to the atmospheric life of nitrate (τ) and calculations indicate τ is around 15 h during the diurnal sampling period. In terms of δ15N(NO3-), it changed largely in our observation, from -2.9‰ to 18.1‰ with a mean of (6.4 ± 4.4) ‰. Correlation analysis implies that the combined effect of NOX emission sources and isotopic fractionation processes are responsible for δ15N(NO3-) variations. Our observations with the aid of model simulation in future study will further improve the understanding of reactive nitrogen chemistry in urban regions.

The role of sulfate and its corresponding S(IV)+NO2 formation pathway during the evolution of haze in Beijing.

To better understand the role of stationary sources during the evolution of haze, we investigated sulfate formation characteristics at different stages of four haze events in Beijing, China. The mass fraction of sulfate in PM2.5 increased while that of nitrate declined slightly during the worsening process of most haze events, consistent with higher ratios of SO42-/NO3- on haze days (0.50 on average) than those on clean days (0.32 on average). Further calculations indicated that sulfate had a higher mass growth rate than nitrate during the haze-worsening process, probably due to regional transport of sulfate from heavy industrial areas accompanied by increased sulfate secondary transformation during polluted periods. We quantitatively evaluated the contribution of the S(IV) + NO2 reaction (pH-dependent) in sulfate formation during the haze evolution. The production rate (PS(IV)+NO2) of the S(IV) + NO2 pathway ranged from 1.97 × 10-4 to 5.91 (mean: 0.39) µg·m-3·h-1. Its proportion to sulfate total heterogeneous production rate (PS(IV)+NO2/Phet) was generally correlated positively with PM2.5 concentrations, indicating the relative importance of this pathway on haze days. Due to the mutual restriction between aerosol pH and aerosol liquid water content (ALWC) during haze evolution, the relative contribution of the S(IV) + NO2 pathway to sulfate heterogeneous formation was generally limited to 40%.