本文關(guān)鍵詞：西安市大氣降塵污染特征研究　出處：《長(zhǎng)安大學(xué)》2015年碩士論文　論文類(lèi)型：學(xué)位論文

  更多相關(guān)文章： 大氣降塵 西安市 重金屬 時(shí)空分異 源解析

【摘要】：隨著我國(guó)工業(yè)化和城鎮(zhèn)化的深入推進(jìn),人類(lèi)活動(dòng)使得城市區(qū)域的大氣降塵污染問(wèn)題日益突出。而城市范圍內(nèi)的大氣干、濕沉降降塵,其產(chǎn)生的污染不僅僅局限于大氣環(huán)境,同時(shí)也是城市地表徑流的一個(gè)重要污染來(lái)源。研究大氣降塵污染對(duì)改善城市環(huán)境空氣質(zhì)量和地表水環(huán)境質(zhì)量均具有非常重要的意義。本文選擇對(duì)西安市區(qū)不同功能區(qū)域大氣降塵污染特征以及生態(tài)風(fēng)險(xiǎn)進(jìn)行細(xì)致研究和討論,以期揭示該地區(qū)降塵污染特征和變化規(guī)律,探明大氣降塵對(duì)城市路面徑流污染的貢獻(xiàn),對(duì)以后制定大氣環(huán)境和水環(huán)境保護(hù)對(duì)策和污染防治措施提供科學(xué)依據(jù)。主要研究結(jié)論和結(jié)果如下:通過(guò)采集西安市常年累積的大氣降塵樣品,研究大氣降塵污染特征、重金屬的形態(tài)及其生物有效性、西安市大氣降塵生態(tài)風(fēng)險(xiǎn)評(píng)價(jià)及重金屬源解析等內(nèi)容,得到以下結(jié)論:(1)西安市大氣降塵中的總COD、淋溶COD、無(wú)機(jī)氮素以及金屬元素元素的質(zhì)量濃度變化較大,且在空間分布上極不均勻,除COD以外,它們的污染程度均隨著功能區(qū)的潔凈程度而不斷減弱。降塵中的無(wú)機(jī)氮主要由氨氮和硝態(tài)氮這兩種形態(tài)組成,氨態(tài)氮與硝態(tài)氮的比值普遍大于2;Cu、Pb、Zn這三種城市元素的濃度在工業(yè)區(qū)最高,Ni和Cd元素主要集中于工業(yè)、商業(yè)和居民文教區(qū)且各區(qū)的濃度變化不大,西安市大部分地區(qū)遭受Cd污染。(2)西安市大氣降塵中Pb、Cr和Ni主要以殘?jiān)鼞B(tài)形式存在,重金屬比較穩(wěn)定。Cu主要以殘?jiān)鼞B(tài)和可氧化態(tài)為主,Zn主要以殘?jiān)鼞B(tài)和酸溶態(tài)存在,降塵中的Cd酸溶態(tài)較高。由計(jì)算的生物有效性系數(shù)可知,Zn和Cd的生物有效性系數(shù)K均大于0.2,其可遷移部分、生物可利用部分高,對(duì)環(huán)境的影響較大。(3)西安市大氣降塵中的Cu、Zn、Cr和Ni生態(tài)風(fēng)險(xiǎn)指數(shù)較小,生態(tài)危害等級(jí)低;其次,Pb和As生態(tài)風(fēng)險(xiǎn)等級(jí)為中等;Cd的生態(tài)風(fēng)險(xiǎn)指數(shù)遠(yuǎn)遠(yuǎn)高于其他重金屬,其生態(tài)危害最為嚴(yán)重。由富集因子的計(jì)算結(jié)果亦可知,Cd在各功能區(qū)富集因子均大于20,在所有重金屬中最高,富集程度較強(qiáng)。而Pb和Zn的富集因子在4-10之間,富集顯著。(4)由主成分分析得出,Cu、Fe、Cr和Zn以上元素可能來(lái)源于金屬冶煉、機(jī)械制造、汽車(chē)尾氣排放以及輪胎、發(fā)動(dòng)機(jī)等機(jī)械磨損;Cd、Pb以及As是由燃煤及工業(yè)生產(chǎn)因子貢獻(xiàn);Al、Ca、Ni則來(lái)自于地殼土壤和揚(yáng)塵,屬于自然來(lái)源。通過(guò)采集西安市2014年全年的大氣降塵樣品,對(duì)大氣降塵量的時(shí)空分異特征和大氣降塵污染的時(shí)空分異特征進(jìn)行細(xì)致討論,得到以下結(jié)論:(1)西安市各功能區(qū)在冬春兩季降塵量超標(biāo)嚴(yán)重;夏秋兩季降塵相比參考標(biāo)準(zhǔn)增量也較大,污染比冬春兩季稍弱。西安市大氣降塵通量在不同季節(jié)有顯著差異,在總體上表現(xiàn)出:冬季春季夏季秋季。而不同功能區(qū)降塵量也存在顯著性差異,總體來(lái)看,降塵量在功能區(qū)的變化為:工業(yè)區(qū)商業(yè)區(qū)居民區(qū)旅游區(qū)。(2)西安市大氣降塵中各形態(tài)氮素的濃度存在明顯季節(jié)性差異,硝態(tài)氮在冬季氨氮濃度為全年最高,而對(duì)于氨氮的增加不太明顯。西安市大氣降塵中各金屬元素在四個(gè)季度的質(zhì)量濃度差異明顯,主要表現(xiàn)為冬春兩季高,夏秋兩季較低,且夏秋兩季含量差距很小。西安市不同功能區(qū)各形態(tài)氮素的濃度存在明顯差異,且在不同季節(jié)內(nèi)均表現(xiàn)出相似的分布特征。即:工業(yè)區(qū)商業(yè)區(qū)≈居民區(qū)旅游區(qū)。四個(gè)功能區(qū)的氨氮濃度占有絕對(duì)優(yōu)勢(shì),說(shuō)明西安市的無(wú)機(jī)氮沉降以氨態(tài)氮為主。(3)西安市大氣降塵中金屬元素在不同功能區(qū)的濃度分布有較大的差異。Cu、Pb、Zn、Cd在工業(yè)區(qū)的含量比其他功能區(qū)高出1.3-1.4倍,而As、Ba、Fe的濃度則比其他功能區(qū)低,除Cu、Pb、Ba外,商業(yè)區(qū),居民區(qū)和旅游區(qū)各金屬元素元素含量相對(duì)均勻。各金屬元素的濃度從高到低依次為AlFeBaZnPbCrAsCuNiVCd,這與常年累積降塵中金屬元素濃度的高低規(guī)律基本一致。
[Abstract]:Along with our country industrialization and further promote urbanization, human activities makes the city regional atmospheric dust pollution problems have become increasingly prominent. The city within the scope of the air dry, wet deposition of dust, the pollution is not limited to the atmospheric environment, but also an important source of pollution is also a city of surface runoff. Research on atmospheric dust the pollution is very important to improve air quality of city environment and surface water environment quality of Xi'an city. This paper chooses the atmosphere in different function areas of dust pollution characteristics and ecological risk of detailed research and discussion, in order to reveal the dust pollution and the variation characteristics of atmospheric dust on the City, proven pavement runoff pollution the contribution to provide a scientific basis for the future development of the atmospheric environment and water environment protection and pollution prevention measures. The main conclusions and results are as follows: through collecting Dust samples fall in Xi'an perennial accumulation of atmospheric dust pollution, feature reduction of atmospheric heavy metals, forms and bioavailability of dust, ecological risk assessment and source analysis of heavy metal contents such as reducing atmosphere of Xi'an City, obtained the following conclusions: (1) the total COD in dust in the atmosphere of Xi'an city and the change of inorganic nitrogen leaching COD the concentration of metal elements is large, and the spatial distribution is extremely uneven, except for COD, they are with the degree of pollution clean degree function area decrease. Reduction of inorganic nitrogen in dust is mainly composed of ammonia and nitrate in the two forms of composition, ratio of ammonia nitrogen and nitrate nitrogen generally more than 2; Cu, Pb, Zn concentration of these three elements in the highest city industrial zone, Ni and Cd elements are mainly concentrated in the industrial, commercial and residential district and cultural concentration changed little, Cd pollution suffered in most areas of Xi'an city. (2) the atmosphere of Xi'an City Dust in the Pb, Cr and Ni are mainly in residual form, the metal is relatively stable.Cu mainly in residual fraction and oxidizable fraction, Zn mainly in residual fraction and acid soluble, reducing Cd acid dust in soluble high. By biological effectiveness coefficient shows the calculation of the biological effectiveness coefficient K Zn and Cd are greater than 0.2, which can transfer part, the bioavailable fraction is high, a greater impact on the environment. (3) dust in the atmosphere of Xi'an city Cu, down Zn, Cr and Ni ecological risk index is small, ecological hazard level is low; secondly, Pb and As ecological risk level for secondary students; state risk index of Cd is much higher than other heavy metals, the most serious ecological hazard. By calculating the enrichment factor results also showed that Cd in each functional area of the enrichment factor is greater than 20, the highest among all heavy metals, the enrichment degree of strong. And the enrichment factors of Pb and Zn in 4-10, significantly enriched (4). By principal component analysis The Cu, Fe, Cr and Zn more elements may be derived from metal smelting, machinery manufacturing, automobile exhaust and tyre, engine and other mechanical wear; Cd, Pb and As are contributed by coal and industrial production factor; Al, Ca, Ni from the crust of soil and dust, which belongs to natural sources. By collecting Xi'an city in 2014 the year of the atmospheric dust samples, space-time dust on atmospheric variation characteristics of atmospheric dust pollution and the differentiation characteristics of the detailed discussion, get the following conclusions: (1) the functional district of Xi'an city in the winter two season of dustfall exceed the standard is serious; the summer two season of dust compared to reference the standard increment is large, pollution than in the two season. Xi'an dustfall flux has a significant difference in different seasons showed in general: spring summer autumn and winter. The amount of dust in different functional areas there are also significant differences, overall, the amount of dust in the function Area change: Industrial District Business District residential area tourist area. (2) there are obvious seasonal differences in concentrations of different forms of nitrogen in dust in the atmosphere of Xi'an City, the nitrate concentration of ammonia nitrogen is the highest in winter, and for the addition of ammonia is not obvious. Xi'an dustfali in metal element the mass concentration in the four quarter of the differences, mainly in the two season, summer two season is relatively low, and the summer two season in the gap is very small. There were significant differences among different functional areas of different forms of nitrogen concentration in Xi'an, and in different seasons showed similar distribution characteristics. Namely: Industrial zone the business district is residential area of tourist area. The ammonia concentration of four functional areas have absolute advantage, that of inorganic nitrogen in Xi'an city on the settlement of ammoniacal nitrogen. (3) Xi'an City Atmospheric metal elements in dust has a larger difference in the concentration of.Cu, different functional areas of the distribution of Pb, Zn, C D in the industrial area in 1.3-1.4 times higher than that in other areas of As, Ba, Fe concentration is low than that in other areas, in addition to Cu, Pb, Ba, the business district, the metal element content is relatively uniform residential and tourist area. The metal element concentration from high to low AlFeBaZnPbCrAsCuNiVCd, which is consistent with the level of law perennial accumulation reduced metal elements in dust concentration.

【學(xué)位授予單位】：長(zhǎng)安大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類(lèi)號(hào)】：X513

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