陳小方,張嘉妮,張偉霞,陳柄旭,范麗雅,2,3,葉代啟,2,3*

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化工園區(qū)揮發(fā)性有機(jī)物排放清單及其環(huán)境影響

陳小方1,張嘉妮1,張偉霞1,陳柄旭1,范麗雅1,2,3,葉代啟1,2,3*

(1.華南理工大學(xué)環(huán)境與能源學(xué)院, 廣東廣州 510006；2.華南理工大學(xué)揮發(fā)性有機(jī)物污染治理技術(shù)與裝備國(guó)家工程實(shí)驗(yàn)室,廣東廣州 510006；3.廣東省大氣環(huán)境與污染控制重點(diǎn)實(shí)驗(yàn)室,廣東廣州 510006)

以珠三角某化工園區(qū)為對(duì)象,利用監(jiān)測(cè)計(jì)算法和排放系數(shù)法結(jié)合計(jì)算了園區(qū)內(nèi)企業(yè)的揮發(fā)性有機(jī)物(VOCs)排放量,編制了分物種的VOCs排放清單,并利用該清單估算了VOCs的臭氧生成潛勢(shì)(OFP)和二次有機(jī)氣溶膠生成潛勢(shì),分析了該園區(qū)VOCs排放對(duì)大氣環(huán)境的影響.結(jié)果表明:園區(qū)VOCs排放總量為9118.61t,單個(gè)企業(yè)排放量為2.98~4176.97t不等,園區(qū)內(nèi)共監(jiān)測(cè)到58種VOCs物種,排放量前3位的物種為乙二醇、丙酸甲酯和二甲苯,3者占園區(qū)VOCs排放總量的52.3%.該園區(qū)OFP總量為27733.42t,其中貢獻(xiàn)量最大的企業(yè)為ZR儲(chǔ)運(yùn),占該園區(qū)OFP總量的45.90%.園區(qū)內(nèi)對(duì)OFP貢獻(xiàn)最大的前10物種是二甲苯、乙二醇、甲苯、2-丙基-1-戊醇、癸醛、三甲苯、辛醇、丙酸甲酯、壬醛、和2,4-二甲苯酚,對(duì)OFP的貢獻(xiàn)達(dá)到94.11%.園區(qū)二次有機(jī)氣溶膠(SOA)生成潛勢(shì)總量為11187.41×10-2t,其中貢獻(xiàn)量最大的企業(yè)仍為ZR儲(chǔ)運(yùn),占園區(qū)SOA生成潛勢(shì)總量的37.25%.園區(qū)內(nèi)對(duì)SOA生成潛勢(shì)貢獻(xiàn)最大的前10物種有二甲苯、甲苯、2,4-二甲苯酚、乙苯、三甲苯、叔丁苯、異丙苯、仲丁苯、甲基叔丁基醚和二十烷, SOA生成潛勢(shì)的貢獻(xiàn)為98.93%.利用VOCs排放清單和最大增量反應(yīng)活性(MIR)計(jì)算法以及氣溶膠生成系數(shù)(FAC)計(jì)算法估算區(qū)域OFP和SOA生成潛勢(shì)有助于精確了解區(qū)域的污染情況,對(duì)于制定相應(yīng)的VOCs減排政策起到重要作用.

VOCs排放清單；源譜；臭氧生成潛勢(shì)；二次有機(jī)氣溶膠

近年來(lái),我國(guó)大氣氣溶膠和高濃度近地面臭氧(O3)污染事件頻發(fā),成為當(dāng)前困擾國(guó)家大氣環(huán)境的主要問(wèn)題[1-3].二次有機(jī)氣溶膠(SOA)是大氣氣溶膠的重要組成部分,占大氣有機(jī)氣溶膠的20%~80%[4-5],O3也已成為我國(guó)許多城市環(huán)境空氣的首要污染物,因此O3和SOA的有效控制對(duì)于緩解當(dāng)前我國(guó)大氣環(huán)境的壓力刻不容緩.揮發(fā)性有機(jī)物(VOCs)作為O3和SOA的重要前體物[6-8],其排放和污染越來(lái)越受到國(guó)家的重視[9-11].然而當(dāng)前的控制政策多針對(duì)VOCs排放量進(jìn)行,而研究表明基于臭氧生成潛勢(shì)(OFP)和SOA的削減策略比基于VOCs排放量的削減更有效[8,12-14],可實(shí)現(xiàn)VOCs排放的精準(zhǔn)控制.

21世紀(jì)以來(lái),我國(guó)化工園區(qū)的數(shù)目迅速增加,化工園區(qū)內(nèi)企業(yè)密度大,污染排放集中,化工園區(qū)整體環(huán)境和生態(tài)問(wèn)題開(kāi)始突顯[15].化工園區(qū)企業(yè)主要為石油煉制、石油化工等相關(guān)行業(yè),VOCs排放量大[16-17],組成成分復(fù)雜[18-19],對(duì)人體健康和大氣環(huán)境質(zhì)量的影響很大[20],因此為化工園區(qū)建立準(zhǔn)確的VOCs分物種排放清單,準(zhǔn)確掌握化工園區(qū)VOCs排放特征并進(jìn)行大氣環(huán)境影響分析十分必要.

本研究以珠三角某化工園區(qū)為對(duì)象,對(duì)各環(huán)節(jié)有組織及無(wú)組織排放的VOCs含量水平及組分特征進(jìn)行研究,估算各企業(yè)VOCs排放量,編制園區(qū)VOCs組分排放清單,并利用此清單計(jì)算各個(gè)物種的OFP和SOA生成潛勢(shì),分析園區(qū)VOCs排放對(duì)區(qū)域大氣環(huán)境的影響,為化工園區(qū)VOCs排放的精準(zhǔn)控制提供數(shù)據(jù)基礎(chǔ)并為減排政策的制定和減排措施的執(zhí)行提供科學(xué)支撐.

1 材料與方法

1.1 VOCs的采樣和分析

1.1.1 采樣對(duì)象 珠三角某化工園區(qū)(以下簡(jiǎn)稱“園區(qū)”)是華南地區(qū)大型綜合性化工園區(qū),規(guī)劃用地9.2km2,產(chǎn)業(yè)定位為精細(xì)化工及石化港口倉(cāng)儲(chǔ)物流.目前園區(qū)內(nèi)正常運(yùn)營(yíng)的企業(yè)有22家,主要為石油化工品的倉(cāng)儲(chǔ)和運(yùn)輸?基礎(chǔ)化學(xué)原料制造、合成材料?膠黏劑?日用化學(xué)品的生產(chǎn)等行業(yè).

對(duì)園區(qū)內(nèi)所有正常運(yùn)營(yíng)企業(yè)進(jìn)行現(xiàn)場(chǎng)調(diào)研,結(jié)果匯總見(jiàn)表1,對(duì)每一行業(yè)分別選1~2家共11家代表性企業(yè)進(jìn)行實(shí)地監(jiān)測(cè),基于對(duì)實(shí)際生產(chǎn)過(guò)程中的工藝特征以及調(diào)研情況,在所選企業(yè)廠區(qū)內(nèi)典型生產(chǎn)裝置單元或VOCs產(chǎn)生環(huán)節(jié)布置了采樣點(diǎn).

1.1.2 采樣與分析 (1)采樣方法:排放源樣品的采集使用老化后的美國(guó)Griffin生產(chǎn)的TENAX管吸附采樣,采樣分有組織采樣和無(wú)組織采樣,每個(gè)排放節(jié)點(diǎn)采集2個(gè)平行樣.有組織采樣在使用采樣泵連接TENAX管后外接一聚四氟乙烯管伸入排氣管道中心部位采集,無(wú)組織采樣使用采樣泵連接TENAX管直接在車間或倉(cāng)庫(kù)內(nèi)部均勻移動(dòng)采樣,采樣泵為北京勞保所生產(chǎn)的QC-2型大氣采樣器,采樣系統(tǒng)中連接管路材質(zhì)均為聚四氟乙烯(PTFE).

(2)分析方法:VOCs分析由Griffin-450氣質(zhì)聯(lián)用儀完成,采用《固定污染源廢氣揮發(fā)性有機(jī)物的測(cè)定固相吸附-熱脫附/氣相色譜-質(zhì)譜法》(HJ 734-2014)[21]中的方法, 將保存好的TENAX管放于分析儀器上,在200℃的氣流下脫附0.2min,脫附的氣體進(jìn)入30℃的吸附阱進(jìn)行再濃縮,濃縮完成后將吸附阱迅速升溫到200℃進(jìn)行二次脫附,脫附時(shí)間為2min,最后進(jìn)入GC-MS進(jìn)行定性定量分析,色譜柱為DB-5MS(30m′0.25mm′0.25mm).氣相色譜的載氣為氫氣,升溫程序:初始溫度為40℃,以40℃/min的速率升到200℃,保持2min,分流比為1:9,柱流量為1.12mL/min.質(zhì)譜掃描方式為全掃描,掃描范圍/為33~425amu,目標(biāo)化合物通過(guò)保留時(shí)間和質(zhì)譜圖定性,外標(biāo)法定量.VOCs標(biāo)氣包括含有57種臭氧前體物的混合標(biāo)氣(PAMS)和含有64種化合物的TO-15混合標(biāo)氣(均來(lái)自美國(guó)Spectra Gases Inc.),不同物種的線性相關(guān)系數(shù)范圍為0.94~0.999.

表1 園區(qū)企業(yè)簡(jiǎn)介

(3)質(zhì)量保證與質(zhì)量控制:對(duì)點(diǎn)位布設(shè)、現(xiàn)場(chǎng)采樣?樣品保存?運(yùn)輸?測(cè)試及數(shù)據(jù)處理等全過(guò)程進(jìn)行質(zhì)量控制和質(zhì)量保證,①采樣前將TENAX吸附管在220℃下老化60mim,老化后的采樣管兩端立即用密封帽密封,放入密封袋,并將密封袋存放于裝有活性炭的盒子或干燥器中,4℃保存,一周內(nèi)使用;②采樣前對(duì)廢氣濃度進(jìn)行預(yù)估,控制采樣時(shí)間,避免采樣管吸附飽和,必要時(shí)進(jìn)行預(yù)采樣;③樣品密封避光保存于-20℃冰箱中,48h內(nèi)分析完畢;④設(shè)置實(shí)驗(yàn)空白樣及運(yùn)輸空白樣,扣除實(shí)驗(yàn)過(guò)程及樣品運(yùn)輸過(guò)程中產(chǎn)生的誤差.

1.2 VOCs分物種排放清單建立

1.2.1 監(jiān)測(cè)計(jì)算法[22]

(1)有組織排放量計(jì)算公式:

式中:為排氣筒有組織排放量,mg;為排氣筒排放流量,m3/h;C為排氣筒排放濃度,mg/m3;為排氣筒排放時(shí)間,h.

(2)無(wú)組織排放量計(jì)算方法:

通過(guò)確定不同生產(chǎn)車間內(nèi)廢氣流向?廢氣處理裝置進(jìn)口VOCs量及車間內(nèi)集氣裝置效率的方式計(jì)算無(wú)組織排放量,公式如下:

式中:為車間無(wú)組織排放量,mg;進(jìn)口為廢氣處理裝置進(jìn)口廢氣濃度,mg/m3;進(jìn)口為廢氣處理裝置進(jìn)口廢氣流量,m3/h;進(jìn)口為廢氣處理裝置進(jìn)口廢氣流通時(shí)間,h;集氣為廢氣處理裝置對(duì)應(yīng)集氣裝置效率,%,集氣≠0.其中,集氣效率計(jì)算公式:

式中:實(shí)際為集氣裝置實(shí)際運(yùn)行頻率,Hz;額定為集氣裝置額定頻率,Hz;集氣額定為集氣裝置額定集氣效率,%.

1.2.2 排放系數(shù)法

(1)密封點(diǎn)泄露排放量計(jì)算方法:

式中:TOC為密封點(diǎn)的TOC排放速率,kg/h;SV為修正后的凈檢測(cè)值,μmol/mol;0為密封點(diǎn)的默認(rèn)零值排放速率,kg/h;f為密封點(diǎn)的相關(guān)方程核算排放速率,kg/h;p為密封點(diǎn)的限定排放速率,kg/h.其中,SV參照企業(yè)的LDAR檢測(cè)數(shù)據(jù),排放速率則參考《石化行業(yè)VOCs排放量計(jì)算辦法》中推薦速率.

(2)儲(chǔ)罐呼吸排放量計(jì)算方法:

式中:儲(chǔ)罐為儲(chǔ)罐的VOCs年排放量,kg/a;固為固定頂罐的VOCs年排放量,kg/a;浮為浮頂罐的VOCs年排放量,kg/a.固定頂罐與浮頂罐的計(jì)算方法參照AP-42的計(jì)算公式,不在此贅述.

1.3 OFP估算方法

為了反映不同VOCs物種的OFP和其對(duì)大氣環(huán)境的影響情況,最大增量反應(yīng)活性值(MIR)和OFP已被廣泛應(yīng)用[6,12-14,23]. OFP代表VOCs物種在最佳條件下對(duì)O3生成的最大貢獻(xiàn),OFP的計(jì)算公式如下:

式中:OFP表示VOC物種的臭氧生成潛勢(shì)量,t;VOC表示物種的排放量,t;MIR表示物種的最大增量反應(yīng)活性.MIR值使用Carter等[24]的最新研究成果.

1.4 SOA生成潛勢(shì)估算方法

常用的SOA生成潛勢(shì)估算方法有OC/EC比值法、WSOC法、受體模型法、氣溶膠生成系數(shù)法、示蹤劑產(chǎn)率法以及數(shù)值模擬法[25],其中氣溶膠生成系數(shù)法應(yīng)用最為廣泛[26-28].為較準(zhǔn)確估算園區(qū)排放VOCs各組分對(duì)SOA生成的影響,在建立VOCs排放清單的基礎(chǔ)上,本研究采用氣溶膠生成系數(shù)法計(jì)算大氣的SOA生成潛勢(shì),其計(jì)算公式如下:

式中:SOA表示VOC物種的二次氣溶膠生成潛勢(shì),t;VOC表示物種的排放量,t;FAC表示物種的氣溶膠生成系數(shù).FAC值使用Grosjean等[29-31]、呂子峰等[32]、Dechapanya等[33]的研究成果.

2 結(jié)果與討論

2.1 VOCs分物種排放清單

本研究分物種排放清單的建立分為2個(gè)部分,編號(hào)為1~11的企業(yè)分物種排放清單根據(jù)實(shí)測(cè)企業(yè)的物種及其濃度信息按照監(jiān)測(cè)計(jì)算法或者排放系數(shù)法進(jìn)行計(jì)算獲取,編號(hào)為12~22的企業(yè)按照排放系數(shù)法核算其排放量后利用園區(qū)內(nèi)相同行業(yè)實(shí)地監(jiān)測(cè)企業(yè)VOCs成分譜對(duì)其物種排放量進(jìn)行合理分配獲取.根據(jù)實(shí)地監(jiān)測(cè)結(jié)果,園區(qū)22家企業(yè)VOCs物種總數(shù)為58種,包含烷烴8種、烯炔烴2種、鹵代烴4種、芳香烴14種、含氧VOCs23種以及其他7種VOCs,根據(jù)監(jiān)測(cè)數(shù)據(jù)及源成分譜信息,最終計(jì)算獲取了園區(qū)分物種排放清單見(jiàn)表2.

2015年園區(qū)VOCs排放總量為9118.61t,園區(qū)內(nèi)VOCs排放量大于100t的企業(yè)有10家,占園區(qū)企業(yè)個(gè)數(shù)的45%,大于10t小于100t的企業(yè)有7家,占園區(qū)企業(yè)個(gè)數(shù)的32%,排放量不足10t的企業(yè)僅有5家,說(shuō)明園區(qū)內(nèi)企業(yè)整體排放水平都較高.VOCs排放量前3位的企業(yè)為ZR儲(chǔ)運(yùn)、YH儲(chǔ)運(yùn)和ZSHGD儲(chǔ)運(yùn),其排放量分別為4176.97、1297.10和1160.27t,三者占園區(qū)VOCs排放總量的72.7%,排放量前3位全部屬于儲(chǔ)運(yùn)行業(yè),說(shuō)明在該園區(qū)VOCs排放量控制方面,儲(chǔ)運(yùn)行業(yè)需加以重點(diǎn)監(jiān)管.

在測(cè)得的58種VOCs物種中,排放量前3位的為乙二醇、丙酸甲酯和二甲苯,其排放量分別為1913.91,1608.18,1242.65t,占園區(qū)VOCs排放總量的52.3%,應(yīng)列為重點(diǎn)監(jiān)管物種.排放來(lái)源最多的物種為甲苯,在22家企業(yè)均有檢測(cè)到,其次是苯酚和二甲苯,出現(xiàn)頻次分別為21和20次,這在選擇重點(diǎn)監(jiān)管物種時(shí)也應(yīng)當(dāng)予以考慮.

表2 園區(qū)分企業(yè)分物種排放清單(t)

續(xù)表2

物種類別物種編號(hào)物種名稱各企業(yè)VOCs排放量 1213141516171819202122合計(jì) 烷烴12,2-二甲基丁烷0.000.02n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.0.13 2己烷0.379.3311.38n.d.64.441.8615.8317.906.321.44n.d.232.32 3辛烷*n.d.n.d.11.930.04n.d.n.d.n.d.n.d.n.d.n.d.n.d.24.90 4壬烷*0.245.88n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.7.71 5癸烷*n.d.n.d.0.13n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.0.64 6十二烷*n.d.n.d.n.d.0.12n.d.n.d.n.d.n.d.n.d.n.d.n.d.1.56 7十四烷*n.d.n.d.n.d.0.15n.d.n.d.n.d.n.d.n.d.n.d.1.978.01 8二十烷*n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.0.52 烯炔烴9莰烯n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.0.58 10檸檬烯n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.4.09 鹵代烴11三氯甲烷n.d.n.d.3.32n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.7.06 121,2-二氯乙烷n.d.n.d.0.15n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.0.31 13氯乙烯n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.1.21 14氯苯*n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.0.02 芳香烴15苯*n.d.n.d.n.d.0.05n.d.n.d.n.d.n.d.n.d.n.d.n.d.1.71 16甲苯*5.27131.078.700.01126.793.6631.1635.2212.442.83119.61693.27 17~19a二甲苯*0.174.350.46n.d.612.1517.66150.42170.0460.0513.670.091242.65 20~22b三甲苯*n.d.n.d.n.d.0.1558.161.6814.2916.165.711.30n.d.123.81 23乙苯*n.d.n.d.n.d.n.d.62.961.8215.4717.496.181.41n.d.131.37 24異丙苯*n.d.n.d.n.d.0.47n.d.n.d.n.d.n.d.n.d.n.d.2.0033.12 25正丙苯*n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.0.46 26仲丁苯*n.d.n.d.0.310.12n.d.n.d.n.d.n.d.n.d.n.d.2.5837.53 27叔丁苯*n.d.n.d.n.d.0.0341.811.2110.2711.614.100.93n.d.70.37 28苯乙烯n.d.n.d.0.05n.d.0.170.000.040.050.020.00n.d.0.43 含氧VOCs29乙醇n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.0.96 30乙二醇n.d.n.d.n.d.n.d.965.0127.84237.13268.0694.6721.55n.d.1913.91 31辛醇0.112.82n.d.n.d.450.1012.98110.60125.0344.1610.05n.d.899.21 32二丙二醇n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.0.02 332-丙基-1-戊醇0.081.931.27n.d.442.0512.75108.62122.7943.379.872.55897.62 342-(己氧基)乙醇n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.0.25 35苯甲醇n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.1.68 36苯酚*0.040.900.770.1780.612.3319.8122.397.911.801.07172.50 372,4-二甲苯酚*n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.0.18 38二丙二醇單甲醚0.020.52n.d.0.00n.d.n.d.n.d.n.d.n.d.n.d.n.d.10.74 39甲基叔丁基醚*0.389.44n.d.0.03280.338.0968.8977.8727.506.260.01569.85 40二乙醚n.d.n.d.n.d.n.d.33.710.978.289.363.310.75n.d.66.85 41二甲醚n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.0.06 42壬醛*0.030.700.15n.d.38.011.109.3410.563.730.85n.d.76.61 43癸醛*0.020.370.270.00106.253.0626.1129.5110.422.37n.d.213.00 44丙烯醛0.061.45n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.1.99 45異佛爾酮n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.n.d.0.37

續(xù)表2

注:n.d.表示該企業(yè)未檢測(cè)到此物種;a二甲苯中包含鄰二甲苯、間二甲苯和對(duì)二甲苯三種物質(zhì);b三甲苯中包含1,2,3-三甲苯、1,2,4-三甲苯和1,3,5-三甲苯三種物質(zhì);*標(biāo)記的為用于計(jì)算SOA生成潛勢(shì)的VOCs.

2.2 OFP分析

表3 園區(qū)各企業(yè)VOCs排放量與OFP的比較

2.2.1 不同企業(yè)OFP貢獻(xiàn) 園區(qū)2015年OFP總量為27733.42t.如表3,OFP最大的企業(yè)為16號(hào)ZR儲(chǔ)運(yùn),其OFP為12729.96t,為占該園區(qū)OFP總量的45.90%,企業(yè)VOCs排放量的排名和OFP排名基本一致,部分企業(yè)如3號(hào)LS制藥、2號(hào)JT能源、14號(hào)JT化工、11號(hào)DC化工排放量排名高于OFP排名,結(jié)合表2企業(yè)的排放物種分析發(fā)現(xiàn)這些企業(yè)的VOCs物種多為MIR值較小的烷烴,而MIR值較高的芳香烴類物質(zhì)則占比相對(duì)較少,如3號(hào)LS制藥芳香烴類物質(zhì)的排放量?jī)H占總排放量的5.5%;反之如1號(hào)RY化工、8號(hào)SDM化工、12號(hào)LT化工則芳香烴類物質(zhì)含量較高.單位質(zhì)量VOCs的OFP值可以反映一個(gè)企業(yè)排放的VOCs臭氧生成能力的大小,如圖1所示,7號(hào)CH化工的OFP/排放量值最大,說(shuō)明CH化工排放的VOCs污染物種的O3生成能力最大,對(duì)照其VOCs成分譜發(fā)現(xiàn)該企業(yè)MIR值較大的芳香烴類物質(zhì)排放占企業(yè)總排放量的近一半,故其最終的OFP/排放量值較大.排放量大的企業(yè)對(duì)大氣環(huán)境的影響不容忽視,但對(duì)于那些排放量雖然較小但是單位質(zhì)量VOCs的OFP值較高的企業(yè)也應(yīng)當(dāng)加以足夠重視.

2.2.2 不同物種OFP貢獻(xiàn) 圖2表示園區(qū)內(nèi)對(duì)OFP貢獻(xiàn)最大的前10種物種的占比,分別是二甲苯(9604.86t,33.92%)、乙二醇(5760.88t,20.77%)、甲苯(2689.88t,9.70%)、2-丙基-1-戊醇(2450.52t, 8.84%)、癸醛(1316.33t,4.75%)、三甲苯(1309.95t, 4.72%)、辛醇(1213.94t,4.38%)、丙酸甲酯(1013.15t,3.65%)、壬醛(473.44t,1.71%)和2,4-二甲苯酚(464.02t,1.67%),這10種物種對(duì)OFP的貢獻(xiàn)為94.11%,盡管園區(qū)內(nèi)測(cè)到的物種數(shù)超過(guò)50種,但是對(duì)OFP起到關(guān)鍵貢獻(xiàn)作用的是這10種物質(zhì).二甲苯的排放量比乙二醇和丙酸甲酯都要少很多,但其OFP貢獻(xiàn)卻為第一位,與其較高的MIR值密不可分,三甲苯雖然MIR值最高,但其排放量相對(duì)較少,OFP貢獻(xiàn)排名相對(duì)靠后,說(shuō)明物種對(duì)OFP的貢獻(xiàn)不能單單靠排放量或者M(jìn)IR值決定,需要經(jīng)過(guò)綜合的計(jì)算,確定物種的OFP排名以便制定更加精準(zhǔn)的針對(duì)物種的減排策略.

圖1 園區(qū)各企業(yè)VOCs排放量與OFP的比較

圖2 前10物種對(duì)園區(qū)OFP的貢獻(xiàn)

2.3 SOA生成潛勢(shì)分析

2.3.1 不同企業(yè)SOA貢獻(xiàn) 園區(qū)2015年SOA總量為11187.41′10-2t.如表4,SOA生成潛勢(shì)最大的企業(yè)為16號(hào)ZR儲(chǔ)運(yùn),其SOA生成潛勢(shì)為4167.68′10-2t,占該園區(qū)SOA總量的37.25%.除了排放量占絕對(duì)優(yōu)勢(shì)的前4家企業(yè)外,其余大部分企業(yè)的SOA排名和排放量排名存在些許差別,這與本研究使用的氣溶膠生成系數(shù)法計(jì)算SOA方法的局限性有關(guān)[32],本研究監(jiān)測(cè)到的物種能夠進(jìn)行SOA生成潛勢(shì)估算的僅有26種,仍有許多物種因缺乏產(chǎn)率數(shù)據(jù)而無(wú)法估算其SOA生成潛勢(shì),個(gè)別企業(yè)如3號(hào)LS制藥,其監(jiān)測(cè)得到的能夠估算SOA生成潛勢(shì)的物種僅有5種,而排放量占比超過(guò)90%的另外6種物質(zhì)的SOA生成潛勢(shì)則暫無(wú)法估算,故其SOA排名遠(yuǎn)落后于排放量排名.同OFP類似,單位質(zhì)量的VOCs的SOA生成潛勢(shì)同樣可以反應(yīng)一個(gè)污染源產(chǎn)生SOA能力的大小.如圖3,SOA生成潛勢(shì)能力最大的企業(yè)是10號(hào)QS樹(shù)脂,對(duì)照其VOCs成分譜發(fā)現(xiàn),該企業(yè)可用于估算SOA生成潛勢(shì)的污染物排放占總排放量的92.67%,單單SOA生成潛勢(shì)較大的甲苯即占總排放量的87.05%.

表4 園區(qū)各企業(yè)VOCs排放量與SOA生成潛勢(shì)的比較

圖3 園區(qū)各企業(yè)VOCs排放量與SOA生成潛勢(shì)的比較

圖4 前10物種對(duì)園區(qū)SOA生成潛勢(shì)的貢獻(xiàn)

2.3.2 不同物種SOA貢獻(xiàn) 圖4表示園區(qū)內(nèi)對(duì)SOA生成潛勢(shì)貢獻(xiàn)最大的前10種物種的占比,分別是二甲苯(43.84t,43.65%)、甲苯(37.44t, 33.46%)、2,4-二甲苯酚(8.62t,7.71%)、乙苯(7.09t,6.34%)、三甲苯(3.47t,3.10%)、叔丁苯(1.83t,1.64%)、異丙苯(1.32t,1.18%)、仲丁苯(0.98t,0.87%)、甲基叔丁基醚(0.57t,0.51%)和二十烷(0.52t,0.47%).這10種物種對(duì)SOA生成潛勢(shì)的貢獻(xiàn)為98.93%,可以看到對(duì)SOA生成潛勢(shì)起到關(guān)鍵貢獻(xiàn)作用的物質(zhì)也比較集中.值得注意的是二甲苯、甲苯、三甲苯和2,4-二甲苯酚無(wú)論是對(duì)OFP或者是SOA貢獻(xiàn)率都在前10位,在制定相應(yīng)的減排及監(jiān)管政策時(shí)應(yīng)予以重點(diǎn)關(guān)注.

2.4 不確定性分析

本研究VOCs排放清單的建立使用了監(jiān)測(cè)計(jì)算法和排放系數(shù)法,故其不確定性來(lái)源主要有3個(gè):(1)采樣及分析過(guò)程,如采樣時(shí)間的不同、儀器操作熟練程度的不同等都會(huì)造成一定的不確定性;(2)活動(dòng)水平,活動(dòng)水平主要通過(guò)企業(yè)填報(bào)獲取,部分企業(yè)管理水平低,活動(dòng)水平的填報(bào)存在一定的誤差,造成了估算結(jié)果的不確定性;(3)排放因子,排放因子會(huì)根據(jù)生產(chǎn)工藝控制水平的不同而實(shí)際存在,因而排放因子的選取也會(huì)造成一定不確定性.OFP清單和SOA生成潛勢(shì)清單以VOCs排放清單為基礎(chǔ)建立,除了上述3個(gè)不確定因素外,MIR值的不確定性和FAC值的不確定性也會(huì)相應(yīng)導(dǎo)致OFP及SOA生成潛勢(shì)的不確定性,因而在進(jìn)行研究時(shí)要盡量選取權(quán)威單位最新的MIR值和FAC值研究成果,降低OFP清單和SOA生成潛勢(shì)清單的不確定性.

3 結(jié)論

3.1 園區(qū)VOCs排放總量為9118.61t,VOCs排放量前3位的企業(yè)為ZR儲(chǔ)運(yùn)、YH儲(chǔ)運(yùn)和ZSHGD儲(chǔ)運(yùn),其排放量分別為4176.97,1297.10, 1160.27t,三者占園區(qū)VOCs排放總量的72.7%.排放量前3位的物種為乙二醇、丙酸甲酯和二甲苯,其排放量分別為1913.91,1608.18,1242.65t,占園區(qū)VOCs排放總量的52.3%.

3.2 園區(qū)OFP總量為27733.42t,貢獻(xiàn)最大的企業(yè)為ZR儲(chǔ)運(yùn),占該園區(qū)OFP總量的45.90%.對(duì)比單位質(zhì)量VOCs的OFP值發(fā)現(xiàn),CH化工排放的VOCs污染物種的臭氧生成能力最大.園區(qū)內(nèi)對(duì)OFP貢獻(xiàn)最大的前10物種是二甲苯、乙二醇、甲苯、2-丙基-1-戊醇、癸醛、三甲苯、辛醇、丙酸甲酯、壬醛、和2,4-二甲苯酚,這10種物種對(duì)OFP的貢獻(xiàn)達(dá)到94.11%.

3.3 園區(qū)SOA總量為11187.41×10-2t,貢獻(xiàn)最大的企業(yè)為ZR儲(chǔ)運(yùn),占該園區(qū)SOA總量的37.25%.貢獻(xiàn)量較大的物種有二甲苯、甲苯、2,4-二甲苯酚、乙苯、三甲苯、叔丁苯、異丙苯、仲丁苯、甲基叔丁基醚和二十烷,這10種物種對(duì)SOA生成潛勢(shì)的貢獻(xiàn)為98.93%.

3.4 不同化工園區(qū)VOCs排放及污染情況千差萬(wàn)別,利用VOCs排放清單和MIR計(jì)算法以及氣溶膠生成系數(shù)法估算區(qū)域OFP和SOA生成潛勢(shì)有助于精確了解區(qū)域的污染情況,掌握各污染源的貢獻(xiàn)率以及各個(gè)前體物的貢獻(xiàn)率,對(duì)于制定與之匹配的VOCs減排政策起到關(guān)鍵作用.

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VOCs emission inventory of a chemical industry park and its influence on atmospheric environment.

CHEN Xiao-fang1, ZHANG Jia-ni1, ZHANG Wei-xia1, CHEN Bing-xu1, FAN Li-ya1,2,3, YE Dai-qi1,2,3*

(1.College of Environment and Energy, South China University of Technology, Guangzhou 510006, China；2. National Engineering Laboratory for VOCs Pollution Control Technology and Equipment, South China University of Technology, Guangzhou 510006, China；3.Guangdong Provincial Key Laboratory of Atmospheric Environment and Pollution Control, Guangzhou 510006, China)., 2017,37(11)：4062~4071

Speciated VOCs emission inventory of a chemical industry park in the PRD area was developed by field monitoring and emission factors.Then the ozone formation potential (OFP) and the secondary organic aerosols (SOA) formation potential were estimated to assess the influence of VOCs emission on the atmospheric environment. Total emissions of VOCs in the park was 9118.61t, and the emissions of each enterprise ranged from 2.98t to 4176.97t. There were 58kinds of VOCs in the park. The top 3species were ethylene glycol, methyl propionate and xylene, which contributed 52.3% to the total VOCs emissions. The total OFP in the park was 27733.42t, of which the largest contributor was ZR storage and transportation Co. Ltd, accounting for 45.90%. The top 10OFP species in the park were xylene, ethylene glycol, toluene, 2-propyl-1-pentanol, decanal, trimethylbenzene, octanol, methyl propionate, nonanal and 2,4-dimethyl phenol, which contributed 94.11% to the total OFP. The total SOA formation potential in the park was 11187.41 × 10-2t, and the largest contributor was ZR, accounting for 37.25%. The top 10SOA formation potential species in the park were xylene, toluene, 2,4-dimethyl phenol, ethylbenzene, trimethylbenzene, tert-butylbenzene, cumene, sec-butylbenzene, methyl tert-butyl ether and eicosane. They contributed 98.93% for the total SOA formation potential. Using VOCs emission inventory and MIR and FAC to estimate the regional OFP and SOA formation potential helps us to comprehend the regional pollution accurately, and it plays a significant role in formulating VOCs emission reduction policies.

VOCs emission inventory；source profiles；ozone formation potential；secondary organic aerosols

X51

A

1000-6923(2017)11-4062-10

陳小方(1993-),女,河南焦作人,華南理工大學(xué)碩士研究生,主要從事?lián)]發(fā)性有機(jī)物污染控制研究.發(fā)表論文6篇.

2017-04-25

環(huán)境保護(hù)公益性行業(yè)科研專項(xiàng)(201409019);中央高校基本科研業(yè)務(wù)費(fèi)專項(xiàng)資金資助項(xiàng)目(2014ZM0068)

* 責(zé)任作者, 教授, cedqye@scut.edu.cn