1 Introduction

Polycyclic aromatic hydrocarbons(PAHs)and their derivatives are associated with the incomplete combustion of organic material,arising from episodes of volcanic eruptions,forest fires(Bjorseth and Ramdahl 1985),and from human activities of burning fossil fuels(Baek et al.1991).Because of their inertness and volatility,PAHs can travel long distances in the air and be distributed in different environmental media,leading to widespread pollution(Wang et al.2006).

In high latitude or high-altitude areas,PAHs are transferred and trapped in the ice and snow via wet atmospheric deposition(rain,snow,etc).Over time,significant amounts of PAHscanbeaccumulated insuchlocations.Wheniceand snow melt as a result of seasonal temperature changes,the accumulated PAHs will be released to other environmental compartmentssuch assurrounding water,soil,and air,thus causing adetrimental impact to theecosystem of theregion.The general trend of global warming is making this dire situationeven morepressing.Therefore,itisvery important to investigate PAHs in ice and snow from glacier(Li et al.2010)and study theirorigin,distribution,and transport.Until now,research on organic pollutants,particularly PAHs in snow and ice,have been mainly focused on the north and southpoles(Kangetal.2012;Herbertetal.2005;Gregorand Gummer 1989;Halsall 2004;Jaffrezo et al.1993),Greenland(Jaffrezo etal.1994),and the Alpsregion(Carreraetal.2001;Villaet al.2006;Finizo et al.2006).Studiesof PAHs in the Qinghai Tibet Plateau region started fairly late and publications on the topic are still scarce(Li et al.2010)although the sediment core and road dusts were carefully studied(Han etal.2015;Weietal.2015).Wangetal.(2008)studied levels and distribution of organochlorine pesticides and PAHsin iceand snow from the Dasuopu glacier.Wang et al.(2007)reported concentrations of organochlorine pesticidesin new snow samplesat four different altitudesin east Rongbuk glacier of the Everest region and studied their correlationswith altitude.Lietal.(2010)investigated on the distribution and source of the PAHs in ice and snow from four glaciersincluding the Qilian Mountain Qiyiglacier and the Tanggula Dongkemadiglacier.More recently,Yu et al.(2014)studied thedistributionand thesourceof the PAHsin snow over a short period in the Hailuogou glacier,Mt.Gongga.

Inthiswork,snow samplesfromthe Hailuogou glacier of Mt.Gongga in China were collected over a 3-year period from 2012 to 2014,and their concentrations were analyzed for 16PAHs.Themainpurposeof thispreliminarystudywas to determine the levels of PAHs in this glacier and try to identify the distribution and source of these PAHs and‘to estimate their transport distance from origin.

所谓应用软件，主要是为了实现用户的特定目的和用途，进而编制计算机的应用软件，主要是通过利用计算机来解决具体实际问题。应用软件实际上就属于一系列功能进行组合，并且做到程序集合相互协作，具有特定程序，对人们的日常生活解决问题有着比较普遍的应用。

1.1 Sample collection

In January of each year,three snow sampleswere collected from Hailuogou for a total of nine samples over the 3-year period from 2012 to 2014.The sampling sitesare shown in Fig.1.The thickness of snow cover was always greater than 25 cm.Snow samples were collected with a clean stainless-steel shovel and packed in a 10-L clean aluminum drum which was sealed with three layers of aluminum paper.The sample information is given in Table 1.The amount of each sample was equivalent to 3–4 L of water.

由此可以看出，峨眉武术的攻防意识不仅很好地表达了武术的本质即技击性，还把峨眉武术的技艺特征展现的淋漓至尽，让峨眉武术的形与技展现独特的魅力。除此之外，峨眉武术除了拥有深邃的技艺哲理之外，还拥有特色的身体文化意蕴。

2 Experimental

2.1 Sample pretreatment

A solid phasemembraneextraction method wasadopted for the enrichment of PAHsfrom snow samples.The C18 solid phase extraction disks membrane(Supelco Analytical,diameter 47 mm)was fixed on a sand core suction filter device.The membrane was activated by passing through 5.0 mL of cyclohexane,n-hexane,methanol,and purewater each in sequence.All of the organic reagents used were HPLC grade.The snow sample was melted at room temperature and the upper clear liquid was loaded on the activated C18 membrane.The flow rate was regulated between 12 and 30 mL·min-1.The eluent was discarded,and 5.0 mL of n-hexane was then added to the C18 membrane and let soaking for 10 min before being eluted.This step was repeated three times.The combined eluent was passed through a chromatography column filled with anhydrous sodium sulfate(activated in a muffle furnace at 400°C for 24 h),and the volumewasfurther reduced to 1.0 mL under astream of high purity nitrogen.A procedureblank(3 L of pure water)was processed along with the snow samples.

2.2 Sample analysis

2.2.1 Reference standards and reagents

Sixteen certified PAHs standards were purchased from AccuStandard(USA),including Naphthalene(Nap),Acenaphthylene(Ace),Acenaphthene(Acp),Fluorene(Fle),Phenanthrene(Phe),Anthracene(Ant),Fluoranthene(Fla),Pyrene(Pyr),Benzo(a)anthracene(BaA),Chrysene(Chry),Benzo(b)fluoranthene (BbF),Benzo [k]fluoranthene(BkF),Benzo[a]pyrene(BaP),Indeno[1,2,3-cd]pyrene(InP),Dibenz[a,h]anthracene(DahA),and Benzo(g,h,i)-perylene(BghiP).Individual stock solutions at concentrations of 100.00 μg·mL-1 each were prepared in dichloromethane–acetone 50:50(v:v).The working standard solutions were prepared by mixing each of the PAH stock solutions and diluting with dichloromethane–acetone 50:50 for a final concentration of 2.00 μg·mL-1 each.

Fig.1 Map of sampling sites

Table 1 Sample information

Sample site Sampling time Altitude(m) Latitude Longitude Sampling depth(cm)1201 January 2012 3170 29°33′19′′N 101°58′11′′E 0–20 1202 January 2012 3250 29°33′54′′N 101°58′45′′E 0–20 1203 January 2012 3470 29°34′00′′N 101°58′55′′E 0–20 1301 January 2013 3100 29°34′03′′N 101°59′55′′E 0–20 1302 January 2013 3130 29°34′01′′N 101°59′50′′E 0–20 1303 January 2013 3180 29°34′57′′N 101°59′42′′E 0–20 1401 January 2014 3110 29°34′04′′N 101°58′59′′E 0–20 1402 January 2014 3140 29°34′02′′N 101°58′56′′E 0–20 1403 January 2014 3190 29°33′54′′N 101°58′45′′E 0–20

All organic solventswere HPLCgradefrom Changzheng Chemical Reagent Co.Ltd.(Chengdu,China).Milli-Qwater was used as pure water.Unless otherwise stated,all the reagentsused inthisstudy wereof analytical gradeor higher.

The results for individual 16 PAHs over the 3-year period from 2012 to 2014 are listed in Tables 2,3 and 4 of Appendix 1,and they are plotted in Fig.2.The amount of individual PAHs varies widely,ranging from non-detectable(DahA and BghiP)to～100 ng·L-1(Phe).Among the 16 PAHs that are reported here,nine PAHs(Nap,Ace,Acp,Fle,Phe,Fla,Pyr,BaA,BkF)were highest for the year 2012,four(Chry,BbF,BaP,INP)for 2013 and one(Ant)for 2014.This change in dominance possibly indicates a change in the source of PAHs over the 3-year period.

2.2.2 GC–MSconditions

Analyses were performed using a 7890-5975 Gas Chromatography–Mass Spectrometer(GC–MS)(Agilent Technologies,Santa Clara,CA)equipped with an autosampler(Triplus Co.USA).Separations were facilitated using an HP-5MS analytical column,30 m×0.25 mm×0.25μm(SN:USB439554H,Agilent Technologies).

Thecarrier gaswashelium(99.999%purity)with aflow rate of 2.0 mL·min-1 at 164.6 kPa.Injections were made in the splitless mode with an injection volume of 2.00μL.The injector temperature was 290°C.The temperature program was as follows:holding initial temperature at 100 °C for 1 min,ramping to 240 °C at 10 °C·min-1(linear),holding for 5.0 min,ramp to 280°C at 20 °C·min-1(linear)and holding for 8.0 min.

●If finding frost in the morning, spread ashes of yak dung and firewood directly on crops.

According to Colmsjo et al.(1986),Simoneit et al.(1993),and Dominguez et al.(1996),theratio of BaA/Chry can be used to differentiate PAHsfrom automobileexhaust and coal combustion produces.The values are typically 0.53±0.06 and 1.11±0.06 for automobile exhaust and coal burning,respectively.Hailuogou snow samples show that the ratio of BaA/Chry in 2012 averaged 1.16,but decreased at 0.44 for 2013 and 2014,respectively(Table 5 in Appendix 1;Fig.4),thus suggesting an increase contribution from automobile activitiesover the 3-year period.

3 Results and discussion

3.1 Qualification of the method

The analysis was performed using a five-point standard calibration curve.Linear correlation coefficients of the 16 PAHs varied from 0.9975 to 0.9998.Recoveries and relative standard deviations were 75.9%–99.2%and 2.8%–15.8%,respectively.Detection limits were ranged from 0.001 to 0.010 μg·L-1.

3.2 Distribution of PAHs in sample area

“And bending down beside the glowing bars”这一句中的“bendingdown”一词是弯下身子的意思，在这个句子里译为“俯下身”或者将其直译为“弯下身子”都是可以的。但是如果把这句中的“bending down”译为“佝偻”则就不符合作者要表达的意思了，因为“bending”是不及物动词，“bendingdown”表示的是一个动作，而不是一种状态，“佝偻”用在这里显然是误译。

The total concentration of the 16 measured PAHs was 452 ± 31 ng·L-1 for 2012,305 ± 54 ng·L-1 for 2013 and 290 ± 30 ng·L-1 for 2014(Fig.3),seemingly suggesting a downward trend which would be in synchronization with the Chinese government’s environmental protection policies installed in energy-saving and emission-reduction.Although the results of year 2014 cannot be considered as significantly different from thoseof year 2013,thefact that apart from 2 exceptions,all other PAHs are lower in 2014 seems suggesting the downward trend of PAHs emission.Regardless of the trend,measured PAH concentrations are still much higher in the Hailuogou glacier in comparison to those from the Qinghai-Tibet Plateau glacier between 20.45 and 60.57 ng·L-1(Li et al.2010)and some remote mountains in Europe between 5.6 and 81 ng·L-1(Carrera et al.2001).

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3.3 Origin of PAHs

3.3.1 Source of PAHs

In spite of its limitations,many researchers have used ratiosof PAHsto tentatively identify their sourcesin whichthe same molecular weight but different structure(i.e.,isomers)are used in the calculation.Among them Phenanthrene(Phe)/Anthracene(Ant),Fluoranthene(Fla)/Pyrene(Pyr),Benzo[a]Anthracene(BaA)/Chrysene(Chry),and Benzo[b]Fluoranthene(BbF)/Benzo[k]Fluoranthene(BkF)are included(Guinan et al.2001;Lee et al.1977;Yunker et al.2002;Colmsjo et al.1986;Simoneit et al.1993;Dominguez et al.1996).It isimportant to select PAH isomerswhoseratiosare stable during their emission,migration,and deposition.In their simulating studies of atmospheric particles,Behymer and Hites(1985)showed that Fluoranthene(Fla)and Pyrene(Pyr),and Benzo[a]Anthracene(BaA)and Chrysene(Chry)have very similar half-lifes and are highly stable,and therefore they can be used reliably for pollution source identification.

Fig.2 Concentration distribution of PAHs in snows

Fig.3 Inter-annual distribution and trend of total PAHs in snow

Fig.4 Cross chart of PAHs ratio

The isomer ratio characteristics in ice and snow from Hailuogou are shown in Table 5.Research conducted by Yunker et al.(2002)has indicated that the ratio of Fla/(Pyr+Fla)from petroleum crude oil pollution istypically less than 0.4;this ratio gets greater than 0.5 for wood and coal burning and between 0.4 and 0.5 for petroleum refinery products.The ratio value from Hailuogou was greater than 0.5(see Table 2;Fig.4),suggesting that the PAHs in ice and snow from Hailuogou are mainly from coal and timber burning.

3.3.2 Estimation of distance from emission source

The mass spectrometry measurements were carried out through an electron impact(EI,70 eV,230°C)coupled with a full scan mode.Other parameters included scanning range of 0–500 amu,transmission temperature of 150 °C and solvent delay time of 2.0 min.

In summary,datafrom Hailuogou snow samplesseem to suggest that the PAHswere mainly coming from wood and coal burning early on(2012),and automobile activities contributed more significantly in 2013 and 2014.Pollution from petroleum industries was much less than expected in the study area.This conclusion fits well with the characteristics of local industry,residence,and recent development of tourism in the surrounding areas.The Hailuogou glacier is located in the Ganzi district of the southeast Sichuan Province and surrounded by mining industry.It is also close to several largest cities in Western China,including Chengdu and Chongqing.Pollution from industrial emissions,mining in particular,has become a serious concern.In addition,it is estimated more than 1 million touriststravel to the Hailuogou glacier by automobileseach year,and this number has been steadily increasing in the last years(Administration of Hailuogou scenic spot 2015).Several hundred restaurants and hotels have been built recently,and nearly half of them burn coal and wood as their energy sources.Almost all local residents use coal and timber for their cooking and heating needs on an everyday basis.All these factors are leading to a much higher amount of PAHs as compared to Qinghai-Tibet Plateau glacier and the characteristic PAH ratio patterns in snow from the Hailuogou glacier.

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In this study,2,3,and 4-ring PAHs have high loadings in snow from the Hailuogou glacier,and the sum of them accounted for 96.4%,91.6%,and 96.0%of total PAHs in 2012,2013,and 2014,respectively.The distance of migration,or mobility of PAHs is directly related to their molecular weights,as with a lower molecular weight,a PAH likely migrating further in the atmosphere.

The 120 h backward trajectories were calculated using the hybrid single-particle lagrangian integrated trajectory model and the NOAA data downloaded from http://ready.arl.noaa.gov/hypub-bin/traj1.pl.The trajectory end points were set at 500 m above the sampling site.Back trajectories showed that the air mass originates from different directions(Fig.5).

Fig.5 Backward trajectories for Hailuogou(left 2012;middle 2013;right 2014)

Fig.6 The maximum range of emission sources of the Hailuogou snow PAHs

where Dt(km)is the longest possible distance that a PAH can travel in the atmosphere;COH(mol·cm-3)is the average concentration of OH free radical in the atmosphere;SW(m·s-1)is the wind speed; is the concentration ratio of phenanthrene and anthracene at the site of emission; is the concentration ratio of anthracene and phenanthrene in snow samples(destination).

Analyses of snow samples from the Hailuogou glacier revealed high concentrations of 16 PAHs,ranging from 452 ± 31 to 290 ± 30 ng·L-1 over the years from 2012 to 2014,demonstrating a remarkable decreasing trend,which may suggest the possible consequence of implementation of more strict air pollution law(Air pollution prevention action plan,2013).Compounds with 2–4 rings are accounted for more than 90%of the total PAHs.The maximum travel distance of these PAHs was estimated to be～500 km.The main source of the PAHs is likely coming from coal combustion with increasing contributions from automobile emissions in more recent years.This conclusion is in agreement with the characteristics of coal as a main energy source and recent development in tourism around the Hailuogou area.

The wind speed,Sw,used in our calculation was the maximum possible wind speed of 60 m·s-1(Gatey and Miller 2007)instead of the actual wind speed,since we intended to estimate the longest possible travel distance.Also,the lowest possible OH radical concentration of 0.3×106 molecules cm-3 in the atmosphere(Hewett and Harrison 1985)was used for the same reason.The value of wastaken from coal burning,which isestimated at 5.67(Galarneau 2008,US EPA).The average values of at the Hailuoguo sampling sites were 0.117,0.131,and 0.125 for 2012,2013,and 2014,respectively.The maximum distance between the emission source and Hialuogou was then estimated to be 492,357,and 413 km for 2012,2013,and 2014,respectively.

An accurate estimate of the distance travelled by PAHs isan important step in determining thelocation of emission and deciphering their origin to better protecting the environment.Li et al.(2014)have established a model to estimate PAH travel distance in the atmosphere,based on factors such as the ratio between the concentrations of Phenanthrene(Phe)and Anthracene(Ant)in the samples collected at the destination and at the emission source the concentration of OH free radicals and wind speed.The travel distance for Hailuogou was then estimated as follows:

Therefore,the concentrations of PAHs in the snow samples should reflect the PAHs emissions surrounding Hailuogou.Figure 6 shows areas and cities within 500 km radius of Hailuoguo,which cover part of Sichuan,Yunnan,Chongqing and Tibet.

4 Conclusions

张子翔：画院要根据自身体制类别的不同和各地经济发展不平衡特点，以求真务实的精神进行改革。认不清改革的形势，安于现状，不思进取，会逐步被时代所淘汰。画院在当前的形势之下，存在着诸多与改革不相适应的地方，管理体系混乱，制度约束缺损，队伍青黄不接，资金保障不足，阵地窗口萎缩等问题，阻碍着画院的发展壮大。画院要发展，就应在领导班子、编制体制、队伍建设、阵地建设、创作研究、藏品管理等方面进行大胆的改革，逐步地、稳健地向前推进，以应对不断发展的社会形势需要。

Acknowledgements This study was supported by the National Natural Science Foundation of China(41073085,41573014)and the programof Sichuan Provincefor researchinnovationteamof universities(12TD001).The authors thank Prof.Belzile N and Chen YW at Laurentian University(Canada)and Dr.S.Huang at Mallinckrodt Biopharmaceuticals(USA)for the helpful edits and valuable discussions.

Appendix 1:GC/MSresults of 16 PAHs in Hailuoguo snow samples

See Tables 2,3,4 and 5.

水系规划建设投入的资金巨大、建设周期长，必须与新城的建设时序密切结合，只有安排合理的实施计划，方能发挥水系规划的最大效益。

Table 2 PAH results for 2012

PAH Quantitative ion(M/Z)Sample content(μg·L-1) Average sample content(μg·L-1)1201 1202 1203 Naphthalene(Nap) 128 0.0661 0.0621 0.0879 0.0720±0.0139 Acenaphthylene(Ace) 152 0.0626 0.0724 0.0630 0.0660±0.0056 Acenaphthene(Acp) 154 0.0616 0.0714 0.0689 0.0673±0.0051 Fluorene(Fle) 166 0.0478 0.0492 0.0479 0.0483±0.0008 Phenanthrene(Phe) 178 0.0975 0.0846 0.1179 0.1000±0.0168 Anthracene(Ant) 178 0.0121 0.0095 0.0134 0.0117±0.0020 Fluoranthene(Fla) 202 0.0361 0.0365 0.0321 0.0349±0.0024 Pyrene(Pyr) 202 0.0227 0.0270 0.0232 0.0243±0.0024 Benzo(a)anthracene(BaA) 228 0.0079 0.0081 0.0083 0.0081±0.0002 Chrysene(Chry) 228 0.0072 0.0060 0.0081 0.0071±0.0010 Benzo(b)fluoranthene(BbF) 252 0.0050 ND 0.0047 0.0049±0.0002 Benzo[k]fluoranthene(BkF) 252 0.0068 ND 0.0078 0.0073±0.0007 Benzo[a]pyrene(BaP) 252 0.0041 0.0038 0.0043 0.0041±0.0002 Indeno[1,2,3-cd]pyrene(InP) 276 ND ND ND –Dibenz[a,h]anthracene(DahA) 278 ND ND ND –Benzo(g,h,i)perylene(BghiP) 276 ND ND ND –0.4375 0.4306 0.4875 0.4519±0.0310

Table 3 PAH results for 2013

PAH Quantitative ion(M/Z)Sample content(μg·L-1) Average sample content(μg·L-1)1301 1302 1303 Naphthalene(Nap) 128 0.0270 0.0280 0.0456 0.0335±0.0105 Acenaphthylene(Ace) 152 0.0428 0.0255 0.0226 0.0303±0.0109 Acenaphthene(Acp) 154 0.0382 0.0256 0.0260 0.0299±0.0072 Fluorene(Fle) 166 0.0412 0.0409 0.0500 0.0440±0.0052 Phenanthrene(Phe) 178 0.0634 0.0766 0.1026 0.0809±0.0004 Anthracene(Ant) 178 0.0095 0.0121 0.0118 0.0112±0.0014 Fluoranthene(Fla) 202 0.0200 0.0197 0.0275 0.0224±0.0044 Pyrene(Pyr) 202 0.0180 0.0161 0.0278 0.0206±0.0063 Benzo(a)anthracene(BaA) 228 0.0028 0.0034 0.0043 0.0035±0.0008 Chrysene(Chry) 228 0.0084 0.0083 0.0147 0.0105±0.0037 Benzo(b)fluoranthene(BbF) 252 0.0066 0.0081 0.0174 0.0107±0.0059 Benzo[k]fluoranthene(BkF) 252 0.0025 0.0030 0.0030 0.0028±0.0003 Benzo[a]pyrene(BaP) 252 ND ND 0.0050 0.0050 Indeno[1,2,3-cd]pyrene(InP) 276 ND ND 0.0077 0.0077 Dibenz[a,h]anthracene(DahA) 278 ND ND ND –Benzo(g,h,i)perylene(BghiP) 276 ND ND ND –0.2804 0.2673 0.3660 0.3046±0.0536

Table 4 PAH results for 2014

PAH Quantitative ion(M/Z)Sample content(μg·L-1) Average sample content(μg·L-1)1401 1402 1403 Naphthalene(Nap) 128 0.0589 0.0602 0.034 0.0510±0.0148 Acenaphthylene(Ace) 152 0.0272 0.0238 0.0175 0.0228±0.0049 Acenaphthene(Acp) 154 0.0189 0.0161 0.0122 0.0157±0.0034 Fluorene(Fle) 166 0.0422 0.0269 0.0309 0.0333±0.0079 Phenanthrene(Phe) 178 0.0974 0.0622 0.119 0.0929±0.0287 Anthracene(Ant) 178 0.0179 0.0078 0.0190 0.0149±0.0062 Fluoranthene(Fla) 202 0.0235 0.0236 0.0242 0.0238±0.0004 Pyrene(Pyr) 202 0.0154 0.0168 0.0145 0.0156±0.0012 Benzo(a)anthracene(BaA) 228 0.0032 0.0036 0.0018 0.0029±0.0010 Chrysene(Chry) 228 0.0040 0.0070 0.0062 0.0057±0.0016 Benzo(b)fl uoranthene(BbF) 252 0.0028 0.0041 0.0030 0.0033±0.0007 Benzo[k]fl uoranthene(BkF) 252 0.0027 0.0023 0.0033 0.0028±0.0005 Benzo[a]pyrene(BaP) 252 0.0030 0.0022 0.0019 0.0024±0.0006 Indeno[1,2,3-cd]pyrene(InP) 276 0.0025 0.0030 0.0034 0.0030±0.0004 Dibenz[a,h]anthracene(DahA) 278 ND ND ND –Benzo(g,h,i)perylene(BghiP) 276 ND ND ND –0.3196 0.2596 0.2909 0.2900±0.0300

Table 5 PAH isomer ratios in snow from Hailuogou

Sample Sampling time Altitude(m) Fla/(Pyr+Fla) BaA/Chry 1201 January 2012 3170 0.614 1.097 1202 January 2012 3250 0.575 1.350 1203 January 2012 3470 0.580 1.025 1301 January 2013 3100 0.526 0.333 1302 January 2013 3130 0.550 0.410 1303 January 2013 3180 0.497 0.293 1401 January 2014 3110 0.604 0.800 1402 January 2014 3140 0.584 0.514 1403 January 2014 3190 0.625 0.290

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