Observations of atmospheric pollutants at Lhasa during 2014-2015:Pollution status and the influence of meteorological factors

Atmospheric pollutants including SO_2, NO_2, CO, O_3 and inhalable particulate matter（PM2.5 and PM10） were monitored continuously from March 2014 to February 2015 to investigate characteristics of air pollution at Lhasa, Tibetan Plateau. Species exhibited similar seasonal variations except O_3, with the peaks in winter but low valleys in summer. The maximum O_3 concentration was observed in spring, followed by summer, autumn, and winter. The positive correlation between O_3 and PM10 in spring indicated similar sources of them, and was assumed to be turbulent transport. Temperature was the dominant meteorological factor for most species in spring. High temperature accelerates O_3 photochemistry, and favors air disturbance which is conductive to dust resuspension in spring. Relative humidity（RH） and atmospheric pressure were the main meteorological factors in summer. RH showed negative correlations with species, while atmospheric pressure posed opposite situation. Wind speed（WS） was the dominant meteorological factor in autumn, the negative correlations between WS and species indicated diffusion by wind. Most species showed non-significant correlations with meteorological factors in winter, indicating the dependence of pollution on source emission rather than restriction by meteorology. Pollution weather character indicated that emissions were from biomass burning and dust suspension, and meteorological factors also played an important role. Air stream injection from the stratosphere was observed during O_3 pollution period. Air parcels from Southwest Asia were observed during air pollution period in winter. An enhancement in air pollutants such as O_3 would be expected in the future, more attention should be given to countermeasures for prevention of air pollution in the future.

The association between vitamin D levels and burn factors in different burn types

Background:Patients with burns present with different clinical features depending on the types of burn injury and burn patients with lower levels of vitamin D have worse prognoses and more complications.The study aims to investigate the association between vitamin D levels and burn factors according to each burn type in relation to early intensive rehabilitation therapy initiated for inpatients with burns.Methods:In this retrospective study,we enrolled 757 of 1716 inpatients who underwent rehabilitative therapy between May 2013 and April 2017.Burn types were divided into flame burn,electrical burn and other burns,including scalding,contact and chemical burns.Age,burned body surface area(BSA),wound healing time(WHT),length of hospital stay(LOS)and body mass index were analysed between vitamin D deficient and non-deficient patient groups using Student’s ttests,or Mann-Whitney U test and among three burn types using one-way analysis of variance(ANOVA)or Kruskal-Wallis one-way ANOVA.The relationship between vitamin D levels and burn factors was evaluated using Pearson’s or Spearman’s correlation coefficient tests,and multiple linear regression analysis in different burn groups.Results:In total,88.9%patients were vitamin D deficient,and these patients had a larger burned BSA(p=0.015)and longer WHT and LOS(all p<0.001)than non-deficient patients.Burned BSA,WHT and vitamin D levels showed significant differences in their mean values according to three burn types(all p<0.001).WHT was a communal factor significantly associated with vitamin D levels in all three burn types(p<0.05).The WHT cut-off points to predict vitamin D deficiency were 55 days for flame burn(p<0.001)and 62.5 days for electrical burn(p=0.001).Conclusions:WHTacross all three burn typeswas a common factor associated with vitamin D levels for inpatients with burns who had undergone rehabilitative therapy.Electrical burn patients with vitamin D deficiency,even those with a low burned BSA percentage,showed prolonged wound healing over a two-month post-burn period.Independent of burned BSA,nutritional intervention concerning vitamin D in relation to burn wound healing should be considered to guide early initiation of intensive rehabilitation therapy.

Influence of fuel mass load,oxygen supply and burning rate on emission factor and size distribution of carbonaceous particulate matter from indoor corn straw burning

The uncertainty in emission estimation is strongly associated with the variation in emission factor （EF）,which could be influenced by a variety of factors such as fuel properties,stove type,fire management and even methods used in measurements.The impacts of these factors are complicated and often interact with each other.Controlled burning experiments were conducted to investigate the influences of fuel mass load,air supply and burning rate on the emissions and size distributions of carbonaceous particulate matter （PM） from indoor corn straw burning in a cooking stove.The results showed that the EFs of PM （EFPM）,organic carbon （EFOC） and elemental carbon （EFEC） were independent of the fuel mass load.The differences among them under different burning rates or air supply amounts were also found to be insignificant （p 〉 0.05） in the tested circumstances.PM from the indoor corn straw burning was dominated by fine PM with diameter less than 2.1 μm,contributing 86.4%±3.9% of the total.The size distribution of PM was influenced by the burning rate and air supply conditions.On average,EF PM,EF OC and EF EC for corn straw burned in a residential cooking stove were （3.84±1.02）,（0.846±0.895） and （0.391±0.350） g/kg,respectively.EF PM,EF OC and EF EC were found to be positively correlated with each other （p 〈 0.05）,but they were not significantly correlated with the EF of co-emitted CO,suggesting that special attention should be paid to the use of CO as a surrogate for other incomplete combustion pollutants.

Local PM_(10) and PM_(2.5) emission inventories from agricultural tillage and harvest in northeastern China

Mineral particles or particulate matters（PMs） emitted during agricultural activities are major recurring sources of atmospheric aerosol loading.However,precise PM inventory from agricultural tillage and harvest in agricultural regions is challenged by infrequent local emission factor（EF） measurements.To understand PM emissions from these practices in northeastern China,we measured EFs of PM_（10） and PM_（2.5） from three field operations（i.e.,tilling,planting and harvesting） in major crop production（i.e.,corn and soybean）,using portable real-time PM analyzers and weather station data.County-level PM_（10） and PM_（2.5） emissions from agricultural tillage and harvest were estimated,based on local EFs,crop areas and crop calendars.The EFs averaged（107 ± 27）,（17 ± 5） and 26 mg/m^2 for field tilling,planting and harvesting under relatively dry conditions（i.e.,soil moisture 〈15%）,respectively.The EFs of PM from field tillage and planting operations were negatively affected by topsoil moisture.The magnitude of PM_（10） and PM_（2.5） emissions from these three activities were estimated to be 35.1 and 9.8 kilotons/yr in northeastern China,respectively,of which Heilongjiang Province accounted for approximately45%.Spatiotemporal distribution showed that most PM_（10） emission occurred in April,May and October and were concentrated in the central regions of the northeastern plain,which is dominated by dryland crops.Further work is needed to estimate the contribution of agricultural dust emissions to regional air quality in northeastern China.

Expression characteristics of c-fos, c-myc and bFGF in early burn tissue

Objective To investigate the sequence and characteristics of expression of proto-oncogenes, c-fos, c-myc and endogenous basic fibroblast growth factor (bFGF), in burn tissue from rats. Methods A partial thickness burn of 30% TBSA was created on the backs of Wistar rats. Immunohistochemistry was used to detect the expression of these proteins in normal and burned skin at 3 hours, 6 hours, 1 day, 3 days, 7 days and 14 days postburn.Results Expression of c-fos, c-myc and bFGF was induced by the burn, but these three proteins showed different expression levels in sequence and distribution. Expression of c-fos increased and peaked at 3 hours postburn. Stain positive granules were distributed mainly in the cytoplasm of basal cells and the nuclei of fibroblasts. The expression of bFGF protein increased at 6 hours and peaked at 1 day postburn; it was distributed in the cytoplasm of fibroblasts. C-myc protein peaked at 3 days postburn and was also distributed in the cytoplasm of fibroblasts.Conclusions Thermal injury can induce c-fos, c-myc and bFGF expression and show phasic control and regional distribution. The phasic expression of these three proteins indicates that there maybe a regulatory relationship between proto-oncogenes and growth factors in early burn. This may play an important role in late tissue repair.

Experimental study on early liver injury and expressions of TNF-α mRNA in burn rats with endotoxemia

Objective: To observe tissue distribution and cell localization of TNF α mRNA and its protein and study their role in the pathogenesis of liver injury in burn rats. Methods: An animal model of rats subjected to 20% TBSA Ⅲ degree burns combined with intraperitoneal injection of lipopolysaccharide (LPS) was used for this experiment. The changes of hepatic morphology and functions and serum TNF α content and expression and localization of liver TNF α and TNF α mRNA were determined with light microscope (LM) and electron microscope (EM), quantitative analysis, immunohistochemistry (IHC) and in situ hybridization (ISH). Results: It showed that there were sinusoid reaction, KCs activation and degeneration, necrosis of HCs, and platelets aggregation, fibrins deposition and PMNs attachment in sinusoid. The activity of ALT was obviously elevated and ALB content was slightly decreased. The serum content of TNF α showed peak at 3 hours. TNF α was mainly localized in sinusoid endothelial cells (SECs) and Kupffer cells (KCs), and TNF α mRNA was mainly distributed in KCs, polymorphonuclears neutrophils (PMNs) and macrophages (MPs). Conclusions: It suggests that TNF α mRNA and its protein expression and localization are coincident with the pathological changes of liver injury. TNF α is one of the key cytokines in the pathogenesis of liver injury in burn rats with endotoxemia.