Vitamin D protects intestines from liver cirrhosis-induced inflammation and oxidative stress by inhibiting the TLR4/MyD88/NF-κB signaling pathway.

Liver cirrhosis affects the structures and physiological functions of the intestine. Our previous study revealed that liver injury inhibited 25-hydroxylation of vitamin D (25(OH)-VD). The aim of this study was to investigate the roles and mechanisms of vitamin D in liver cirrhosis-induced intestinal injury. The rat liver cirrhosis model was established through the administration of carbon tetrachloride (CCl4) for 8 weeks. Hematoxylin-eosin staining was performed to unveil the intestinal injury induced by liver cirrhosis. Enzyme-linked immunosorbent and reverse transcription PCR (RT-PCR) analysis were used to determine the levels of 25(OH)-VD, vitamin D receptor, Cytochrome P450 24A1 (CYP24A1), and α-defensin 5 (DEFA5) in rat and human serum of liver cirrhosis. Furthermore, liver cirrhosis rats were treated with low-dose (500 IU/kg) and high-dose (2,000 IU/kg) vitamin D intraperitoneally. The expression levels of TLR4/MyD88/NF-κB signaling pathway were evaluated by RT-PCR and Western blot. In conclusion, we determined the deficiency of vitamin D and down-regulation of DEFA5 and intestinal damage induced by liver cirrhosis. Moreover, vitamin D effectively inhibited liver cirrhosis-induced intestinal inflammation and oxidative stress through the TLR4/MyD88/NF-κB pathway. Vitamin D might be a promising therapeutic strategy for future treatment of liver-induced intestinal injury.

Mechanistic study for mutual interactions of Pb2+ and Trichoderma viride.

Fungi play significant roles in the geochemical processes of heavy metals in the environment. However, the interaction between heavy metals and fungi, especially at the cellular level, is quite complicated and remains unknown. This study explored the mutual interaction mechanism between Pb2+ and Trichoderma viride by combining batch experiments, spectroscopy, and in vitro approaches. Batch experiments revealed that Pb2+ had toxic effect on T. viride, originally causing the biomass of T. viride decreased from 1.3 g in the control group to 0 g in the presence of 200 mg/L Pb2+. The difference in biomass further led to varied pH, even decreasing from 5.7 at the outset to 3.4 due to the acid-production properties of T. viride. Moreover, structural deformation and damage of T. viride mycelium appeared when exposed to Pb2+, and were more evident at a higher dose of Pb2+ exposure. The growth curve exhibited that T. viride gradually adapted to Pb2+ exposure, which related to Pb2+ exposure concentration. Further, intracellular and extracellular secretions of T. viride changed with varying exposure concentrations of Pb2+, indicating that T. viride adapted differently to different concentrations of Pb2+, and MT participated in the detoxification of T. viride. SEM-EDX showed that T. viride could bio-adsorb and bioaccumulate more Pb2+ when exposed to more Pb2+, which was closely related to the content of P. And carbonyl, phosphate, and amino groups of T. viride participated in the Pb2+ biosorption onto T. viride, as evidenced by FT-IR and XPS. Meanwhile, the biomineralization and reduction of Pb2+ by T. viride were observed by XRD and XPS, which might be a possible factor for Pb2+ biosorption and bioaccumulation. CLSM showed that the bio-adsorbed and bioaccumulated Pb2+ were mainly distributed in the membrane of T. viride mycelium.

Interaction behaviors of Cr(VI) at biotite-water interface in the presence of HA: Batch, XRD and XPS investigations.

The interaction behaviors of heavy metals and micaceous minerals are extremely important to understand the environmental behaviors of heavy metals. In this work, the interaction behaviors of Cr(VI) and biotite in the presence and absence of HA were studied combining batch and spectroscopic approaches. Batch experiments showed that biotite had the ability to remove Cr(VI) from the water and the removal markedly increased with decreasing pH. However, sorption of total Cr onto biotite increased with increasing pH (2.0-4.0), whilst quickly decreased above pH âˆ¼ 4.0. It was worth noting that redox process of Cr(VI) to Cr(III), caused by structural Fe(II) on biotite, was another important factor for the high removal of Cr(VI) in a pH range of 2.0-4.0. Ionic strength also influenced Cr(VI) removal that Cr(VI) removal became higher with increasing ion strength. The presence of HA did not show obvious macroscopic effect on Cr(VI) removal, however, HA could cover biotite surface, and promote the sorption of total Cr onto biotite and attenuate the reduction effect caused by Fe(II) on biotite. Spectroscopic approaches, like FT-IR, XRD and XPS further confirmed the existence of Cr(III) on biotite interacting with Cr(VI) and the reduction of Cr(VI) to Cr(III) was drove by the Fe(II) dissolving from biotite to Fe(III). Further, sorption effect and reduction effect competitively contributed to the Cr(VI) removal by biotite, and reduction effect played a more important role at lower pH.

Drug resistance characteristics of Mycobacterium tuberculosis isolates obtained between 2018 and 2020 in Sichuan, China.

We investigated the drug resistance of Mycobacterium tuberculosis isolates from patients with tuberculosis (TB) and HIV, and those diagnosed with only TB in Sichuan, China. TB isolates were obtained from January 2018 to December 2020 and subjected to drug susceptibility testing (DST) to 11 anti-TB drugs and to GeneXpert MTB/RIF testing. The overall proportion of drug-resistant TB (DR-TB) isolates was 32.1% (n = 10 946). HIV testing was not universally available for outpatient TB cases, only 29.5% (3227/10 946) cases had HIV testing results. The observed proportion of multidrug-resistant TB (MDR-TB) isolates was almost double than that of the national level, with approximately 1.5% and 0.1% of the isolates being extensively drug resistant and universally drug resistant, respectively. The proportions of resistant isolates were generally higher in 2018 and 2019 than in 2020. Furthermore, the sensitivities of GeneXpert during 2018-2020 demonstrated a downward trend (80.9, 95% confidence intervals (CI) 76.8-85.0; 80.2, 95% CI 76.4-84.1 and 75.4, 95% CI 70.7-80.2, respectively). Approximately 69.0% (7557/10 946) of the TB cases with DST results were subjected to GeneXpert detection. Overall, the DR-TB status and the use of GeneXpert in Sichuan have improved, but DR-TB challenges remain. HIV testing for all TB cases is recommended.

Cytotoxic Effect of Graphene Oxide Nanoribbons on Escherichia coli.

The biological and environmental toxicity of graphene and graphene derivatives have attracted great research interest due to their increasing applications. However, the cytotoxic mechanism is poorly understood. Here, we investigated the cytotoxic effect of graphene oxide nanoribbons (GORs) on Escherichia coli (E. coli) in an in vitro method. The fabricated GORs formed long ribbons, 200 nm wide. Based on the results of the MTT assay and plate-culture experiments, GORs significantly inhibited the growth and reproduction of E. coli in a concentration-dependent manner. We found that GORs stimulated E. coli to secrete reactive oxygen species, which then oxidized and damaged the bacterial cell membrane. Moreover, interaction between GORs and E. coli cytomembrane resulted in polysaccharide adsorption by GORs and the release of lactic dehydrogenase. Furthermore, GORs effectively depleted the metal ions as nutrients in the culture medium by adsorption. Notably, mechanical cutting by GORs was not obvious, which is quite different from the case of graphene oxide sheets to E. coli.

S-Trimer, a COVID-19 subunit vaccine candidate, induces protective immunity in nonhuman primates.

SARS-CoV-2 is the underlying cause for the COVID-19 pandemic. Like most enveloped RNA viruses, SARS-CoV-2 uses a homotrimeric surface antigen to gain entry into host cells. Here we describe S-Trimer, a native-like trimeric subunit vaccine candidate for COVID-19 based on Trimer-Tag technology. Immunization of S-Trimer with either AS03 (oil-in-water emulsion) or CpG 1018 (TLR9 agonist) plus alum adjuvants induced high-level of neutralizing antibodies and Th1-biased cellular immune responses in animal models. Moreover, rhesus macaques immunized with adjuvanted S-Trimer were protected from SARS-CoV-2 challenge compared to vehicle controls, based on clinical observations and reduction of viral loads in lungs. Trimer-Tag may be an important platform technology for scalable production and rapid development of safe and effective subunit vaccines against current and future emerging RNA viruses.

Trichoderma viride involvement in the sorption of Pb(II) on muscovite, biotite and phlogopite: Batch and spectroscopic studies.

In this study, batch and spectroscopic approaches were used to explore the sorption of Pb(II) on micas (i.e., muscovite, biotite and phlogopite) in the presence of Trichoderma viride (T. viride). Batch sorption showed that ion exchange, outer-sphere complexes (OSCs) and inner-sphere complexes (ISCs) contributed to Pb(II) sorption on biotite and phlogopite in the pH range of 2.0-7.4, whereas the ISCs were predominant for Pb(II) sorption on muscovite. X-ray diffraction and Fourier transform infrared (FT-IR) analyses have confirmed the changes of structure and surface properties of micas after co-culturing with T. viride, which could improve the sorption capacity of micas to Pb(II). Scanning electron microscopy revealed the bio-mineralization of Pb(II) on T. viride and mica-T. viride composites forming lead phosphates. Furthermore, FT-IR analysis showed that the groups of Si-OH, Al-OH from micas, and carboxyl, phosphate and amino groups from T. viride were synergistically contributing to Pb(II) sorption on mica-T. viride composite. X-ray photoelectron spectroscopy further confirmed that both OSCs and ISCs formed for Pb(II) sorption on micas; however, in the case of mica-T. viride composites, the synergistic effects of T. viride and micas were contributing to Pb(II) sorption through forming the ISCs and biomineralization.

On-site analysis of COVID-19 on the surfaces in wards.

SARS-Cov-2 has erupted across the globe, and confirmed cases of COVID-19 pose a high infection risk. Infected patients typically receive their treatment in specific isolation wards, where they are confined for at least 14 days. The virus may contaminate any surface of the room, especially frequently touched surfaces. Therefore, surface contamination in wards should be monitored for disease control and hygiene purposes. Herein, surface contamination in the ward was detected on-site using an RNA extraction-free rapid method. The whole detection process, from surface sample collection to readout of the detection results, was finished within 45 min. The nucleic acid extraction-free method requires minimal labor. More importantly, the tests were performed on-site and the results were obtained almost in real-time. The test confirmed that 31 patients contaminated seven individual sites. Among the sampled surfaces, the electrocardiogram fingertip presented a 72.7% positive rate, indicating that this surface is an important hygiene site. Meanwhile, the bedrails showed the highest correlation with other surfaces, so should be detected daily. Another surface with high contamination risk was the door handle in the bathroom. To our knowledge, we present the first on-site analysis of COVID-19 surface contamination in wards. The results and applied technique provide a potential further reference for disease control and hygiene suggestions.

Exploring the fate of heavy metals from mining and smelting activities in soil-crop system in Baiyin, NW China.

The activity and fate of heavy metals (HMs) from mining and smelting activities in farmland soil is of great significance to effectively prevent the excessive enrichment of HMs in crops. This study focuses on Baiyin area, a typical mining city in northwest China. In this example, the sources, speciation, and fate of HMs in the farmland soil, and the migration and enrichment characteristics of HMs in the different parts of crops planted in different areas were studied in detail combining the chemical sequential extraction and Pb isotope approaches. Results showed that the mean anthropogenic contributions of HMs in farmland soils were approximately 85%, 88%, 76%, and 41% for the ore district (OD), Xidagou sewage irrigation area (XSIA), Dongdagou sewage irrigation area, and the Yellow River irrigation area, respectively, and the risk that HMs were excessively accumulated in crops in OD and XSIA was high. Compared with soil residual fractions, the isotope ratios 206Pb/207Pb in non-residual fractions (1.1304-1.1669) were closer to the values of local ores, suggesting that anthropogenic HMs from mining and smelting activities were mainly enriched in the non-residual fractions. The isotope ratios 206Pb/207Pb in crops (1.1398-1.1686) further confirmed that those anthropogenic HMs were more easily absorbed and concentrated by crops. HMs contents in leaves from OD and XSIA were generally higher than that in roots, suggesting that atmospheric deposition in OD and XSIA had a greater impact on the HMs concentration of crop leaves，while the excess rate of HMs in grain/fruit was the lowest in all parts of crops. The division and classification of crop planting in mining area can effectively help minimize the risk that HMs from anthropogenic source enter the human body through the food chain.

Continuous thrombocytopenia after SARS-CoV-2 nucleic acid negative in a non-severe COVID-19 patient for several months.

BACKGROUND: Thrombocytopenia was common in the coronavirus disease (Covid-19) patients during the infection, especially in severe COVID-19 patients, but was less in the non-severe Covid-19 patients. However, the platelet count would be restored after antivirus treatment. In this paper, we report continuous thrombocytopenia in a non-severe Covid-19 case after a negative nucleic acid test for Covid-19. CASE PRESENTATION: A non-severe COVID-19 patient had the platelet continuous decrease for several months after the SARS-CoV-2 nucleic acid turning negative, and without well response to the glucocorticoid. The dynamic change of platelet count followed that of the lymphocyte count. After excluding the medicines possibility, immune system disorders, other specific virus infection and specific antibody of platelet, the thrombocytopenia continuously lasted for several months. The upward trend did not begin until June 2020 and she took the tapering dose of prednisone under the instruction of the hematologist. CONCLUSION: Excluding other potentialities inducing thrombocytopenia, we highly hypothesized the SARS-CoV-2 may cause thrombocytopenia by disturbing the immune system to induce the thrombocytopenia in our report,, which needs longer time to restore the immune system and platelet count via the glucocorticoid. We firstly reported this case in order to contribute the clinician to better deal with the patients like this.

Development and evaluation of a Novel RT-PCR system for reliable and rapid SARS-CoV-2 screening of blood donations.

BACKGROUND: The ongoing outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused great global concerns. In contrast to SARS, some SARS-CoV-2-infected people can be asymptomatic or have only mild nonspecific symptoms. Furthermore, there is evidence that SARS-CoV-2 may be infectious during an asymptomatic incubation period. With the discovery that SARS-CoV-2 can be detected in plasma or serum, blood safety is worthy of consideration. STUDY DESIGN AND METHODS: We developed a nucleic acid test (NAT) screening system for SARS-CoV-2 targeting nucleocapsid protein (N) and open reading frame 1ab (ORF 1ab) gene that could screen 5076 samples every 24 hours. The 2019 novel coronavirus RNA standard was used to evaluate linearity of standard curves. Diagnostic sensitivity and reproducibility were evaluated using artificial SARS-CoV-2. Specificity was evaluated with 61 other respiratory pathogens. Diagnostic performance was evaluated by testing two sputum and nine oropharyngeal swab specimens. The reverse transcription polymerase chain reaction (RT-PCR) assay was used to screen SARS-CoV-2 RNA in blood donor specimens collected during the outbreak of SARS-CoV-2 in Chengdu. RESULTS: Limits of detection of the SARS-CoV-2 RT-PCR assay for N and ORF 1ab gene were 12.5 and 27.58 copies/mL, respectively. Intra-assay and interassay for the SARS-CoV-2 RT-PCR assay based on cycle threshold were acceptably low. No cross-reactivity was observed with other respiratory virus and bacterial isolates. The overall agreement value between the SARS-CoV-2 RT-PCR assay and clinical diagnostic results was 100%. A total of 16 287 blood specimens collected from blood donors during SARS-CoV-2 surveillance were tested negative. CONCLUSIONS: A high-throughput NAT screening system was developed for SARS-CoV-2 screening of blood donations during the outbreak of SARS-CoV-2.

Lymphocyte subsets with the lowest decline at baseline and the slow lowest rise during recovery in COVID-19 critical illness patients with diabetes mellitus.

BACKGROUND: Host dysregulation of immune response was highly involved in the pathological process of Coronavirus disease 2019 (COVID-19), especially COVID-19 severe cases with DM. AIM: In this study we aimed at the dynamic change of peripheral lymphocyte and subsets during COVID-19 covery. METHODS: The peripheral lymphocyte and subsets of 95 confirmed cases with COVID-19 from baseline to four weeks were compared between critical illness and non-critical illness cases with or without DM. RESULTS: The dynamic characteristics of lymphocyte and subsets in COVID-19 patients was that it reduced significantly at one week, rapidly elevated to the peak at two weeks after onset, then gradually declined during recovery. The COVID-19 critical illness patients with DM had the lowest decline at one week and the slow lowest rise at two weeks after onset, while COVID-19 non-critical illness patients with DM had the rapid highest rise at two weeks after onset, both of them had similar lymphocyte and subsets at five weeks after onset and lower than those patients without DM. CONCLUSIONS: These findings provide a reference for clinicians that for COVID-19 patients with DM and the lowest decline of lymphocyte and subsets, immunomodulatory therapy as soon as possible might avoid or slow down disease progression; moreover for COVID-19 critical illness patients with or without DM and non-critical illness patients with DM, continuous immunomodulatory therapy in later stages of disease might speed up virus clearance, shorten hospital stay, improve disease prognosis in COVID-19 critical illness patients with DM.

Vitamin D signaling maintains intestinal innate immunity and gut microbiota: potential intervention for metabolic syndrome and NAFLD.

A lack of sunlight exposure, residence in the northern latitudes, and dietary vitamin D insufficiency are coprevalent with metabolic syndrome (MetS), Type 2 diabetes (T2D), and nonalcoholic fatty liver diseases (NAFLD), implying a potential causality and underlying mechanism. Whether vitamin D supplementation or treatment can improve these disorders is controversial, in part, because of the absence of large-scale trials. Experimental investigations, on the other hand, have uncovered novel biological functions of vitamin D in development, tumor suppression, and immune regulation, far beyond its original role as a vitamin that maintained calcium homeostasis. While the large intestine harbors massive numbers of microbes, the small intestine has a minimal quantity of bacteria, indicating the existence of a gating system located in the distal region of the small intestine that may restrain bacterial translocation to the small intestine. Vitamin D receptor (VDR) was found to be highly expressed at the distal region of small intestine, where the vitamin D signaling promotes innate immunity, including the expression of α-defensins by Paneth cells, and maintains the intestinal tight junctions. Thus, a new hypothesis is emerging, indicating that vitamin D deficiency may impair the intestinal innate immunity, including downregulation of Paneth cell defensins, leading to bacterial translocation, endotoxemia, systemic inflammation, insulin resistance, and hepatic steatosis. Here, we review the studies for vitamin D for innate immunity and metabolic homeostasis, and we outline the clinical trials of vitamin D for mitigating MetS, T2D, and NAFLD.

Ultra-fast enrichment and reduction of As(V)/Se(VI) on three dimensional graphene oxide sheets-oxidized carbon nanotubes hydrogels.

The removals of arsenic and selenium pollutants are always urgent desires for the water security. In this study, both sorption and catalysis strategies were combined for the effective removals of As(V) and Se(VI) over magnetic graphene oxide sheets (GOs)-oxidized carbon nanotubes (OCNTs) hydrogels. The sorption behavior facilitated the operation of catalysis reactions, meanwhile, the catalytic reduction promoted the release of occupied sorption sites and then restarted a new sorption-catalysis cycle. The synergic effect of sorption and catalysis realized 258.2 mg g-1 for As(V) enrichment capacity on MPG2T1, and ultra-fast sorption and catalysis equilibriums were identified within 9 min. In the case of Se(VI), a moderate enrichment performance was observed to be 46.2 mg g-1. Similarly, the ultra-fast sorption and reduction of Se(VI) were realized within 2 min. In the competition experiments, only SO42-, SO32-, and HPO42- showed interference for As(V) and Se(VI) removals. These results testified the superiority of the synergy effect of sorption and catalysis, and the feasibility of 3D magnetic GOs-OCNTs hydrogel in practical implementations.

Chlorophyllin Modulates Gut Microbiota and Inhibits Intestinal Inflammation to Ameliorate Hepatic Fibrosis in Mice.

Liver fibrosis is an abnormal wound healing response and a common consequence of chronic liver diseases from infection or alcohol/xenobiotic exposure. At the cellular level, liver fibrosis is mediated by trans-differentiation of hepatic stellate cells (HSCs), which is driven by persistent hepatic and systemic inflammation. However, impaired enterohepatic circulation and gut dysbiosis may indirectly contribute to the liver fibrogenesis. The composition of the gut microbiota depends on diet composition and host factors. In this study, we examined chlorophyllin, derived from green pigment chlorophyll, on gut microbiota, the intestinal mucosal barrier, and liver fibrosis. BALB/c mice received carbon tetrachloride through intraperitoneal injection to induce liver fibrosis and chlorophyllin was administrated in drinking water. The effects of chlorophyllin on liver fibrosis were evaluated for (1) survival rate, (2) hepatic morphologic analysis, (3) inflammatory factors in both the small intestine and liver, and (4) gut microbiota. Our results indicate that oral administration of chlorophyllin could attenuate intestinal and hepatic inflammation and ameliorate liver fibrosis. Importantly, oral administration of chlorophyllin promptly rebalanced the gut microbiota, exhibiting down-regulation of the phylum Firmicutes and up-regulation of the phylum Bacteroidetes. In vitro experiments on intestinal epithelial cells showed that chlorophyllin exposure could inhibit NF-κB pathway via IKK-phosphorylation suppression. In conclusion, this study demonstrates potential application of chlorophyllin to regulate the intestinal microbiota and ameliorate hepatic fibrosis.

Alternation of Gut Microbiota in Patients with Pulmonary Tuberculosis.

One-third of the world's population has been infected with Mycobacterium tuberculosis (M. tuberculosis), a primary pathogen of the mammalian respiratory system, while about 10% of latent infections progress to active tuberculosis (TB), indicating that host and environmental factors may determine the outcomes such as infection clearance/persistence and treatment prognosis. The gut microbiota is essential for development of host immunity, defense, nutrition and metabolic homeostasis. Thus, the pattern of gut microbiota may contribute to M. tuberculosis infection and prognosis. In current study we characterized the differences in gut bacterial communities in new tuberculosis patients (NTB), recurrent tuberculosis patients (RTB), and healthy control. The abundance-based coverage estimator (ACE) showed the diversity index of the gut microbiota in the patients with recurrent tuberculosis was increased significantly compared with healthy controls (p < 0.05). At the phyla level, Actinobacteria and Proteobacteria, which contain many pathogenic species, were significantly enriched in the feces RTB patients. Conversely, phylum Bacteroidetes, containing a variety of beneficial commensal organisms, was reduced in the patients with the recurrent tuberculosis compared to healthy controls. The Gram-negative genus Prevotella of oral origin from phylum of Bacteroidetes and genus Lachnospira from phylum of Firmicutes were significantly decreased in both the new and recurrent TB patient groups, compared with the healthy control group (p < 0.05). We also found that there was a positive correlation between the gut microbiota and peripheral CD4+ T cell counts in the patients. This study, for the first time, showed associations between gut microbiota with tuberculosis and its clinical outcomes. Maintaining eubiosis, namely homeostasis of gut microbiota, may be beneficial for host recovery and prevention of recurrence of M. tuberculosis infection.

New Mycobacterium tuberculosis Beijing clonal complexes in China revealed by phylogenetic and Bayesian population structure analyses of 24-loci MIRU-VNTRs.

Beijing lineage of Mycobacterium tuberculosis constitutes the most predominant lineage in East Asia. Beijing epidemiology, evolutionary history, genetics are studied in details for years revealing probable origin from China followed by worldwide expansion, partially linked to higher mutation rate, hypervirulence, drug-resistance, and association with cases of mixed infections. Considering huge amount of data available for 24-loci Mycobacterial Interspersed Repetitive Units-Variable Number of Tandem Repeats, we performed detailed phylogenetic and Bayesian population structure analyses of Beijing lineage strains in mainland China and Taiwan using available 24-loci MIRU-VNTR data extracted from publications or the SITVIT2 database (n = 1490). Results on genetic structuration were compared to previously published data. A total of three new Beijing clonal complexes tentatively named BSP1, BPS2 and BSP3 were revealed with surprising phylogeographical specificities to previously unstudied regions in Sichuan, Chongqing and Taiwan, proving the need for continued investigations with extended datasets. Such geographical restriction could correspond to local adaptation of these "ecological specialist" Beijing isolates to local human host populations in contrast with "generalist pathogens" able to adapt to several human populations and to spread worldwide.

[Distribution and Source Analysis of Polycyclic Aromatic Hydrocarbons (PAHs) and Organochlorine Pesticides (OCPs) in Soils from Shergyla Mountain, Southeast Tibetan Plateau].

Soils were collected from Shergyla Mountain shade slope and south-facing slope in southeast Tibetan Plateau (TP) in August 2012 and they were measured for polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs)(including HCHs and DDTs). The concentrations of ∑16PAHs ranged from 99.3 to 1984 ng·g-1 dw, with a mean value of 1017 ng·g-1 dw. HCHs and DDTs in soils samples were in the range of 0.37-2.07 ng·g-1 dw (mean 1.15 ng·g-1 dw) and 0.70-43.9 ng·g-1 dw (mean 9.87 ng·g-1 dw), respectively. The concentrations of all measured compounds were much higher than those in central or western TP,and the PAHs concentration was even up to two orders of magnitude. The concentrations of α-HCH and DDTs in south-facing slope increased with altitude, but HCHs and DDTs in shade slope had no significant correlation with altitude. There was no consistent increasing or decreasing trend of PAHs in shade slope with altitude, and the concentrations of PAHs in south-facing slope showed a higher value in lower altitude, indicating the existence of local pollution emissions. The PAHs profile was dominated by lighter constituents (2 & 3-ring accounted for higher than 85%),inferring that the PAHs in the study area were largely influenced by long range atmospheric transport (LRAT) of pollutants. The special diagnostic ratios of PAHs suggested that PAHs were mainly produced by low temperature combustion of biomass and fossil fuels, except that two sampling sites of shade slope had been possibly influenced by oil residue. The relatively low ratios of α/γ-HCH inferred HCHs in the research area was the result of the combined contribution of the historical technical HCHs and Lindan. The ratios of p,p'-DDE/p,p'-DDT and o,p'-DDT/p,p'-DDT indicated DDTs were from the combined contribution of the historical technical DDTs and dicofol. According to the profile of PAHs, HCHs and DDTs and the meteorological conditions of Shergyla Mountain, the transport of PAHs and OCPs in the study area was mainly influenced by the Indian Monsoon.

Dechloranes in lichens from the southeast Tibetan Plateau: Evidence of long-range atmospheric transport.

Dechloranes (Decs) have been recently found to occur widely in the environment even in the remote polar regions. However, the understanding of their environmental fate is rather limited. The Tibetan Plateau (TP) may be an important indicator region to study the long-range atmospheric transport and their fates of these emerging contaminants since it has very limited local sources. In the present study, Dechlorane plus (DP), Dechlorane 602 (Dec 602), Dechlorane 603 (Dec 603) and Dechlorane 604 (Dec 604) were analyzed in lichen samples from the southeast TP. The results showed that only DP and Dec 602 were detected, with a detection frequency of 89% and 100%, respectively. The average concentrations (dry weight) of ΣDP and Dec 602 were 318 pg g(-1) (20-1132 pg g(-1)) and 167 pg g(-1) (27-843 pg g(-1)), respectively. The DP concentration in this study was much higher than those in moss from the remote Ny-Ålesund, Arctic. The concentrations of Dec 602 were found to generally increase with increasing altitude, while DP concentrations seemingly showed an opposite altitudinal trend along the mountain slopes. No stereoselective accumulation or transformation of anti-DP and syn-DP was observed in lichens and the altitudinal behavior of the two isomers was similar. This research documented that Decs are prone to undergo LRAT and cold-trapping by the mountains in the southeast TP.

[Vertical distribution pattern and ecological risk assessment of heavy metals in a sediment core from Pumoyum Co, Tibet].

The sediment core was collected in Pumoyum Co, a lake located in southern Tibetan Plateau, in July 2008. Samples were digested using microwave equipment and analyzed by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES), to determine the content of heavy metals in the sediments. The average concentrations for Cr, Co, Ni, Cu, Zn, Cd, Pb, Mn and Fe were 26.4 µg x g(-1), 6.64 µg x g(-1), 16.2 µg x g(-1), 26.2 µg x g(-1), 50.2 µg x g(-1), 0.363 µg x g(-1), 16.8 µg x g.(-1), 0.302 mg x g(-1) and 9.84 mg x g(-1) , respectively. The concentrations of analysed metals in Pumoyum Co were slightly higher than those in Antarctic, but lower than those from Dianchi in Yunnan, Daihai in Inner Mongolia, the Great lakes in North America and Taihu in China, which were obviously affected by anthropogenic activities. Overall, these metals in sediments from Pumoyum Co represented a low concentration level. Vertical profiles of heavy metals in the sediment core kept stable without large fluctuation and the concentrations in surface slices were relatively higher. Results of principle component analysis and cluster analysis indicated that organic matter and Mn were affected by surface runoff markedly while other metals were mainly correlated to natural diagenetic weathering and atmospheric deposition. Sediment quality guideline and potential ecological risk index were introduced to assess sediment quality and both of their results indicated that the Pumoyum Co as a whole can be ranked as low potential ecological risk.