林承奇,胡恭任,于瑞蓮 (華僑大學(xué)環(huán)境科學(xué)與工程系,福建 廈門 361021)
福建九龍江下游潮間帶沉積物鉛污染及同位素示蹤
林承奇,胡恭任*,于瑞蓮 (華僑大學(xué)環(huán)境科學(xué)與工程系,福建 廈門 361021)
通過分析九龍江下游潮間帶23個(gè)表層沉積物及周邊地區(qū)典型端元組分的鉛含量和鉛同位素組成(206Pb/207Pb和208Pb/206Pb),以評(píng)估鉛的空間分布,并采用鉛同位素二元和三元混合模型探討鉛來源及各源的相對(duì)貢獻(xiàn)率.結(jié)果表明,九龍江下游潮間帶表層沉積物中鉛含量范圍為38.50~128.50mg/kg(平均80.60mg/kg),地質(zhì)累積指數(shù)法、富集系數(shù)法和潛在生態(tài)危害指數(shù)法評(píng)價(jià)結(jié)果表明研究區(qū)沉積物中的鉛為輕度~中等污染與輕度潛在生態(tài)危害.沉積物鉛同位素組成中206Pb/207Pb和208Pb/206Pb的范圍分別為1.1651~1.1924和1.9640~2.1071,大多數(shù)采樣點(diǎn)處沉積物中的鉛主要來源于九龍江上游鉛鋅礦和土壤母質(zhì),受汽車尾氣的影響很??;九龍江河口上端沉積物Pb主要來源為鉛鋅礦、土壤母質(zhì)和燃煤,相對(duì)貢獻(xiàn)率范圍分別為26.74%~56.61%、18.85%~19.91%和24.20%~58.53%;九龍江河口外端沉積物Pb主要來源有鉛鋅礦、土壤母質(zhì)、燃煤和船舶油漆,相對(duì)貢獻(xiàn)率分別為20.06%、13.75%、7.52%和58.67%;其余采樣點(diǎn)處Pb主要來源為鉛鋅礦和土壤母質(zhì),相對(duì)貢獻(xiàn)率范圍分別為20.00%~95.62%和4.38%~80.00%.
鉛同位素;九龍江下游;沉積物;污染源;貢獻(xiàn)率
鉛被廣泛用于許多工業(yè)生產(chǎn)過程并已成為環(huán)境中的重要污染物,因其具有持久性、生物蓄積性和生物不可降解性,已引起世界的廣泛關(guān)注[1-2].自然界中鉛有 4種同位素:204Pb、206Pb、207Pb和208Pb,其中204Pb是穩(wěn)定同位素;206Pb、207Pb、208Pb分別是238U、235U、232Th衰變的終產(chǎn)物,其同位素組成只與源區(qū)的Pb同位素組成特征有關(guān),與重金屬的遷移行為和軌跡無關(guān),具有特殊的“指紋”特征,可用于污染源示蹤[3], 特別是在研究鉛及其他親硫元素(Hg、Ag、Tl、Sb、Zn、Cu等)的重金屬污染來源方面, 已成為一種強(qiáng)有力的手段[4].
九龍江是福建省第二大河流,流經(jīng)龍巖、漳州等市縣并最終注入廈門灣,不僅是龍巖、漳州、廈門三市的重要飲用水源,也是重要的工農(nóng)業(yè)生產(chǎn)水源,其水環(huán)境安全對(duì)福建省乃至海峽西岸經(jīng)濟(jì)區(qū)意義重大[5].九龍江下游位于廈門港西南部,地處海峽西岸經(jīng)濟(jì)發(fā)展區(qū).近年來,九龍江流域經(jīng)濟(jì)與工業(yè)發(fā)展迅速,造成該河口重金屬污染日趨嚴(yán)重.王偉力等[6]對(duì)九龍江口表層沉積物重金屬含量進(jìn)行分析,表明該區(qū)域重金屬存在一定潛在生態(tài)風(fēng)險(xiǎn);于瑞蓮等[7]對(duì)九龍江口表層沉積物重金屬形態(tài)進(jìn)行分析,表明該區(qū)域重金屬已有不同程度富集,且綜合潛在生態(tài)風(fēng)險(xiǎn)較強(qiáng).但關(guān)于九龍江下游表層沉積物中重金屬污染來源解析尚鮮有報(bào)道.
本文通過分析九龍江下游潮間帶表層沉積物鉛含量及其同位素組成,結(jié)合九龍江流域潛在污染源端元組分的鉛同位素組成,評(píng)價(jià)鉛污染狀況并利用鉛同位素的指紋特征示蹤沉積物中鉛污染來源,以期為該地區(qū)重金屬污染防治提供科學(xué)依據(jù).
1.1樣品采集及預(yù)處理
2012年10月期間潮水退至最低時(shí)采集了23個(gè)九龍江下游潮間帶表層0~5cm的沉積物樣品(圖1).
將采集到的樣品放于裝有冰塊的保溫箱中運(yùn)回實(shí)驗(yàn)室,置于冰箱中-20℃冷凍保存 24h.冷凍后的沉積物樣品置于干凈、通風(fēng)、陰涼的實(shí)驗(yàn)臺(tái)面上晾干,用干凈的木棒搗碎,剔除雜物,用瑪瑙研缽輕輕研磨,過63 μm尼龍篩,篩下樣裝入干凈的聚乙烯自封塑料袋中密封保存?zhèn)溆?
詳細(xì)調(diào)查九龍江流域及其周邊環(huán)境,九龍江下游鉛污染的潛在污染源可能有四個(gè)方面:一是上游鉛鋅礦開采過程釋放;二是汽車尾氣排放;三是工業(yè)生產(chǎn)過程中燃煤等釋放;四是船舶運(yùn)輸釋放.本研究系統(tǒng)采集了九龍江下游周邊汽車尾氣塵、燃煤塵、九龍江上游鉛鋅礦和九龍江下游土壤母質(zhì)樣品以及船舶油漆等作為端元組分.端元組分樣品采集方法參見胡恭任等[3]的報(bào)道.
圖1 九龍江下游潮間帶表層沉積物采樣點(diǎn)分布圖Fig.1 Sampling locations of intertidal surface sediments in Jiulong River downstream
1.2鉛含量和同位素組成分析
表層沉積物樣品經(jīng)過預(yù)處理后,送至北京核工業(yè)地質(zhì)研究院分析測(cè)試研究中心進(jìn)行分析測(cè)定.鉛含量采用Finnigan-MAT公司的BLEMENT 型ICP-MS進(jìn)行測(cè)定,以近岸海洋沉積物成分分析標(biāo)準(zhǔn)物質(zhì)GBW07314進(jìn)行質(zhì)量控制,測(cè)定結(jié)果的相對(duì)標(biāo)準(zhǔn)偏差(<5.0%)在誤差允許范圍內(nèi);表層沉積物和端元組分的鉛同位素比值分析樣品的制備在北京核工業(yè)地質(zhì)研究院分析測(cè)試中心同位素超凈實(shí)驗(yàn)室中完成.按 DZ/T0184.12 -1997標(biāo)準(zhǔn)分析流程對(duì)鉛進(jìn)行分離與純化.同位素比值測(cè)定在英國(guó)產(chǎn)IsoProbeT熱電離質(zhì)譜儀上完成,全流程本底鉛為10-9量級(jí),用國(guó)際標(biāo)準(zhǔn)物質(zhì)NBS981監(jiān)控儀器分析工作狀態(tài),NBS981的207Pb/206Pb分析值為 0.91460±0.00005,分析精度優(yōu)于0. 05%.詳細(xì)測(cè)試過程見文獻(xiàn)[8-9]
2.1表層沉積物中鉛含量S
圖2 九龍江下游潮間表層帶沉積物鉛含量及富集系數(shù)Fig.2 Lead contents and enrichment factors of the intertidal surface sediments in Jiulong River downstream
九龍江下游潮間帶表層沉積物中鉛含量見圖2.各采樣點(diǎn)鉛含量范圍為38.50~128.50mg/kg,平均值為80.60mg/kg.除采樣點(diǎn)20#外,其余采樣點(diǎn)沉積物中鉛含量均超過福建省海岸帶土壤環(huán)境背景值[10](39mg/kg),鉛濃度最高出現(xiàn)在采樣點(diǎn)2#處,達(dá)到背景值的3.29倍;以Pb作為指標(biāo)時(shí),九龍江下游沉積物符合中國(guó)海洋沉積物質(zhì)量標(biāo)準(zhǔn)(GB 18668-2002)規(guī)定的第二類沉積物質(zhì)量標(biāo)準(zhǔn).九龍江下游潮間帶表層沉積物中鉛含量隨著流域的流向總體呈下降趨勢(shì),表明九龍江上游可能存在鉛污染源;采樣點(diǎn)1#~4#、19#、21#、22# 和23#處鉛含量較高,說明這些采樣點(diǎn)處的Pb可能受其他因素的影響.
2.2表層沉積物中鉛污染評(píng)價(jià)
采用不同評(píng)價(jià)方法對(duì)九龍江下游潮間帶沉積物中鉛含量進(jìn)行評(píng)價(jià).以福建省海岸帶土壤環(huán)境背景值作為參比值,采用Müller提出的地質(zhì)累積指數(shù)法[11]評(píng)價(jià),沉積物中 Pb的地質(zhì)累積指數(shù)Igeo為-0.60~1.14,對(duì)照地質(zhì)累積指數(shù)分級(jí)標(biāo)準(zhǔn)(表1),82.6%的沉積物中Pb表現(xiàn)為輕度污染,8.7%的沉積物中Pb表現(xiàn)為偏中度污染,其余為無污染.
表1 地質(zhì)累積指數(shù)(Igeo)與污染程度Table 1 Index of geoaccumulation (Igeo) and pollutiondegree
為了進(jìn)一步評(píng)估沉積物中鉛的富集程度,應(yīng)用富集系數(shù)(EF)進(jìn)行分析,公式如下[12]:
式中:(Pb/Y)i為沉積物中 Pb元素與參比元素(Y)的比值;(Pb/Y)lith為自然背景中Pb元素與參比元素(Y)的比值.參比元素的選取應(yīng)滿足在風(fēng)化、沉積等表生過程中化學(xué)性質(zhì)穩(wěn)定等條件[13].實(shí)際應(yīng)用中常作為參比元素的有:Al、Cs、Zr、Nb、Y、Li、Fe、Sc、Co等[12,14].本研究中同時(shí)測(cè)定了元素 Fe、Co、Sc等在沉積物中的含量,結(jié)果發(fā)現(xiàn)Sc元素在沉積物中的含量相對(duì)較穩(wěn)定(CV=0.11),且接近于背景值.故將 Sc作為參比元素,用于評(píng)估Pb的富集程度(圖2).沉積物中Pb的富集系數(shù)范圍為0.9~3.15,平均值為1.79.根據(jù)EF值對(duì)元素富集程度的評(píng)價(jià)標(biāo)準(zhǔn)[15],九龍江下游潮間帶69.5%的沉積物中Pb表現(xiàn)為輕度富集(1<EF<2),其余沉積物中Pb表現(xiàn)為中等富集(2<EF<5).
采用 Hakanson提出的潛在生態(tài)危害指數(shù)(RI)法[16]進(jìn)行評(píng)價(jià),沉積物中Pb的潛在生態(tài)危害系數(shù)為 4.96~16.47,對(duì)照潛在生態(tài)危害系數(shù)分級(jí)標(biāo)準(zhǔn)(表2),沉積物中Pb均表現(xiàn)為輕度潛在生態(tài)危害.
綜上可知,九龍江下游潮間帶沉積物中Pb表現(xiàn)為輕度~中度污染與輕度潛在生態(tài)危害.
表2 潛在生態(tài)危害程度分級(jí)Table 2 Degree of potential ecological risk
九龍江下游潮間帶沉積物中Pb含量與世界上其他流域下游及河口等沉積物中鉛含量對(duì)比(表 3)表明:九龍江下游潮間帶表層沉積物中鉛含量比廈門西港、泉州灣、珠江、長(zhǎng)江等一些國(guó)內(nèi)河流下游或海灣以及國(guó)外如印度Dhamara河口等地區(qū)沉積物中的鉛含量高,已存在一定程度的污染,應(yīng)引起一定的重視.
表3 不同研究區(qū)域表層沉積物中鉛含量Table 3 Lead Contents in the surface sediments indifferent studied area
2.3潛在污染源與表層沉積物中鉛同位素組成
九龍江下游潛在污染源端元組分中鉛同位素組成測(cè)定結(jié)果列于表 4.可見,土壤母質(zhì)、上游鉛鋅礦、汽車尾氣塵、火電廠燃煤、船舶油漆的206Pb/207Pb的值分別為:1.1923~1.2012(平均值1.1956)、1.1752~1.1832(平均值1.1796)、1.1111~1.1489(平均值1.1301)、1.1430~1.1630(平均值1.1508)和1.1678~1.1757(平均值1.1717);上述各端元組分的208Pb/206Pb值分別為 2.0722~2.0888(平均值 2.0787)、2.1003~2.1060(平均值2.1025)、2.0310~2.1252(平均值2.0692)、2.0979~ 2.1401(平均值 2.1238)和 1.8475~1.8910(平均值1.8693).其中,土壤母質(zhì)具有最高的206Pb/207Pb值,火電廠燃煤具有最高的208Pb/206Pb值.各端元組分的鉛同位素組成存在明顯差異,因此可以通過鉛同位素組成來區(qū)分不同污染來源的鉛.
九龍江下游潮間帶表層沉積物中鉛同位素組成見表 5.各采樣點(diǎn)沉積物中206Pb/207Pb和208Pb/206Pb的值分別為1.1651~1.1924和2.9640~2.1071.
表4 潛在污染源鉛同位素組成Table 4 Lead isotopic composition of potential sources
比較潛在污染源端元組分和沉積物樣品的鉛同位素組成可知,沉積物樣品的鉛同位素組成與汽車尾氣塵的鉛同位素組成差異較大,說明汽車尾氣不是九龍江下游沉積物中鉛污染的主要來源.
表5 九龍江下游潮間帶表層沉積物鉛同位素組成Table 5 Lead isotopic composition of intertidal surface sediments in Jiulong River downstream
2.4沉積物中鉛來源分析
鉛同位素組成可以用來示蹤鉛的來源,因204Pb含量低,208Pb/204Pb、207Pb/204Pb、206Pb/204Pb的測(cè)定容易受到不同因素干擾,很難全面反映鉛的變化趨勢(shì)并有效識(shí)別污染源[3],因此許多學(xué)者采用測(cè)試精度較高的208Pb/206Pb和206Pb/207Pb比值對(duì)鉛污染源進(jìn)行示蹤.土壤母質(zhì)、鉛鋅礦、汽車尾氣塵和火電廠燃煤等端元組分的206Pb/207Pb 和208Pb/206Pb的比值相差較大,故可用206Pb/207Pb 和208Pb/206Pb的比值來追蹤九龍江下游潮間帶沉積物中鉛的污染來源.
不同采樣點(diǎn)表層沉積物與潛在污染源端元組分的鉛同位素組成對(duì)比見圖3.各采樣點(diǎn)表層沉積物的鉛同位素組成與鉛鋅礦和土壤母質(zhì)的鉛同位素組成較接近,說明九龍江下游潮間帶表層沉積物中鉛主要來源于上游鉛鋅礦和土壤母質(zhì);采樣點(diǎn) 1#、4#和 5#的鉛同位素組成還與燃煤的鉛同位素組成接近,說明燃煤對(duì)這3個(gè)采樣點(diǎn)處沉積物中 Pb具有一定的貢獻(xiàn);采樣點(diǎn)23#的鉛同位素組成落于燃煤、鉛鋅礦、土壤母質(zhì)和船舶油漆之間,說明采樣點(diǎn) 23#處沉積物中Pb來源有燃煤、鉛鋅礦、土壤母質(zhì)和船舶油漆四個(gè)源.汽車尾氣塵的鉛同位素組成與各采樣點(diǎn)沉積物的鉛同位素組成相差較大,說明汽車尾氣對(duì)九龍江下游潮間帶表層沉積物中鉛污染的貢獻(xiàn)很小.
圖3 表層沉積物與端元物質(zhì)鉛同位素組成對(duì)比Fig.3 Comparison between lead isotopes composition of the surface sediments and the potential sources
2.5鉛污染源貢獻(xiàn)率計(jì)算
利用208Pb/206Pb-206Pb/207Pb作圖并進(jìn)行對(duì)比分析,只能定性分析鉛污染的來源,不能計(jì)算各污染源的相對(duì)貢獻(xiàn)率.為了進(jìn)一步評(píng)估鉛污染源,需對(duì)其進(jìn)行定量解析,目前,用于定量解析的方法主要有二元模型和三元模型[29].
二元模型即樣品中的鉛可以看成 2個(gè)主要污染源的混合,計(jì)算公式如下[30]:
式中:f1、f2分別為兩個(gè)污染源的相對(duì)貢獻(xiàn)率.
根據(jù)表層沉積物與端元物質(zhì)鉛同位素組成對(duì)比圖(圖3),各采樣點(diǎn)(除采樣點(diǎn)1#、4#、5#和23#)與鉛鋅礦和土壤母質(zhì)的鉛同位素組成具有較好的線性關(guān)系,說明沉積物中鉛來源于鉛鋅礦和土壤母質(zhì)兩個(gè)主要污染源的混合[31],令 f1和f2分別代表鉛鋅礦和土壤母質(zhì)的相對(duì)貢獻(xiàn)率,則(206Pb/207Pb)1和(206Pb/207Pb)2分別為 1.1796和1.1956.
三元模型用于計(jì)算 3個(gè)主要的污染源和樣品同位素均已知的情況下各污染源的貢獻(xiàn)率,Li等[32]建立的三元模型如下:
式中:f為相對(duì)貢獻(xiàn)率;C為鉛含量,mg/kg;下標(biāo)s、1、2、3分別代表樣品和3個(gè)主要污染源.
根據(jù)表層沉積物與端元物質(zhì)鉛同位素組成對(duì)比圖(圖3),1#、4#和5#采樣處沉積物中Pb來源貢獻(xiàn)率可使用鉛鋅礦-燃煤-土壤母質(zhì)三元模型計(jì)算,令下標(biāo)1、2、3分別代表鉛鋅礦、燃煤和土壤母質(zhì), f1、f2和f3分別為鉛鋅礦、燃煤和土壤母質(zhì)的相對(duì)貢獻(xiàn)率;則(206Pb/207Pb)1、(206Pb/207Pb)2、(206Pb/207Pb)3的值分別為1.1796、1.1508和1.1956;C1、C2、C3的值分別為1118.98, 92.93, 31.09mg/kg.
采樣點(diǎn) 23#處沉積物中鉛來源較復(fù)雜,可能有鉛鋅礦、燃煤、土壤母質(zhì)和船舶油漆四個(gè)來源,目前尚沒有能計(jì)算四個(gè)鉛源貢獻(xiàn)率的模型,從圖3可以看出,采樣點(diǎn)23#處沉積物的鉛同位素比值在船舶油漆、燃煤和土壤母質(zhì)3個(gè)源鉛同位素比值的三角形區(qū)域內(nèi),同時(shí)也在船舶油漆、鉛鋅礦和土壤母質(zhì) 3個(gè)鉛源同位素比值的三角形區(qū)域內(nèi),可利用兩個(gè)三元模型(船舶油漆-燃煤-土壤母質(zhì)、船舶油漆-鉛鋅礦-土壤母質(zhì))相結(jié)合的方式進(jìn)行計(jì)算其貢獻(xiàn)率,分別計(jì)算兩個(gè)三元模型中各鉛源的相對(duì)貢獻(xiàn)率,然后各鉛源貢獻(xiàn)率取平均得各鉛源相對(duì)貢獻(xiàn)率.
根據(jù)以上鉛污染源相對(duì)貢獻(xiàn)率計(jì)算模型,對(duì)九龍江下游潮間帶沉積物中鉛污染源的貢獻(xiàn)率進(jìn)行定量計(jì)算(表6).九龍江下游潮間帶沉積物中鉛主要來源為上游鉛鋅礦,其貢獻(xiàn)率為 20.00%~95.62%,其次為土壤母質(zhì),其貢獻(xiàn)率為 4.38%~80.00%,采樣點(diǎn)1#、4#和5#處燃煤鉛相對(duì)貢獻(xiàn)率分別為26.80%、58.53%和24.20%.這可能與采樣點(diǎn)4#附近的造紙廠使用燃煤鍋爐和采樣點(diǎn)5#北部及采樣點(diǎn) 1#東部的角美綜合工業(yè)區(qū)中的燃煤企業(yè)有關(guān).采樣點(diǎn) 23#處,船舶油漆、燃煤、鉛鋅礦和土壤母質(zhì)的相對(duì)貢獻(xiàn)率分別為 58.67%、7.52%、20.06%和13.75%.對(duì)計(jì)算結(jié)果用式(7)和式(8)計(jì)算進(jìn)行驗(yàn)證. (206Pb/207Pb)計(jì)算和(208Pb/206Pb)計(jì)算的值分別為1.1750和1.9652,與23#處鉛同位素組成的測(cè)定值(表 3)相符,因此計(jì)算結(jié)果可行.采樣點(diǎn) 23#處沉積物中的燃煤鉛貢獻(xiàn)可能來源于附近的嵩嶼電廠,船舶油漆鉛貢獻(xiàn)可能與嵩嶼碼頭較頻繁的船舶運(yùn)輸有關(guān).
式中:f為相對(duì)貢獻(xiàn)率;下標(biāo)1、2、3和4分別代表船舶油漆、燃煤、鉛鋅礦和土壤母質(zhì).
鉛同位素分析表明采樣點(diǎn) 19#、21#和 22#處沉積物中較高的鉛含量主要來源于上游鉛鋅礦和土壤母質(zhì),這與 Hu等[33]的研究結(jié)果有些出入(該文認(rèn)為嵩嶼電廠燃煤對(duì)這些采樣處沉積物具有較多的燃煤鉛貢獻(xiàn)),可能因Hu等采用的是全國(guó)燃煤的鉛同位素組成進(jìn)行分析,其數(shù)值跨度較大而造成一定的誤差,而本文采用的是嵩嶼電廠燃煤鉛同位素組成進(jìn)行分析,結(jié)果應(yīng)更符合實(shí)際情況.采樣點(diǎn)19#、21#和22#處沉積物中鉛含量較高可能是因其處于九龍江入??诒眰?cè)灣口區(qū),水動(dòng)力環(huán)境復(fù)雜,來自九龍江上游和廈門西港的污染物易在此區(qū)域隨泥沙沉積,和轉(zhuǎn)等[34]研究發(fā)現(xiàn)該區(qū)域沉積物以細(xì)顆粒(粉砂和黏土)為主,而細(xì)顆粒沉積物中鉛等重金屬含量一般較高.
表6 九龍江下游潮間帶表層沉積物中鉛主要污染源貢獻(xiàn)率Table 6 Contribution of main sources to total Pb of the intertidal surface sediments in Jiulong River downstream
3.1九龍江下游潮間帶表層沉積物中鉛含量范圍為 38.50~128.50mg/kg,平均 80.60mg/kg,超過福建省海岸帶土壤環(huán)境背景值,與其他流域下游及河口區(qū)沉積物中鉛相比含量略高.地質(zhì)累積指數(shù)法、富集系數(shù)法和潛在生態(tài)危害指數(shù)法的評(píng)價(jià)結(jié)果顯示,九龍江下游潮間帶表層沉積物中Pb表現(xiàn)為輕度~中等污染與輕度潛在生態(tài)危害.
3.2九龍江下游潮間帶表層沉積物的鉛同位素組成中206Pb/207Pb、208Pb/206Pb比值分別為1.1651~1.1924和 1.9640~2.1071.對(duì)比沉積物和潛在污染源端元組分的鉛同位素組成進(jìn)行污染源定性和定量分析,結(jié)果表明,九龍江河口上端沉積物中Pb主要來源于鉛鋅礦、土壤母質(zhì)和燃煤,相對(duì)貢獻(xiàn)率分別為 26.74%~56.61%、18.85%~19.19%和24.20%~58.53%;河口外端沉積物中Pb主要來源于鉛鋅礦、土壤母質(zhì)、燃煤和船舶油漆,相對(duì)貢獻(xiàn)率分別為 20.06%、13.75%、7.52%和58.67%,其余采樣點(diǎn)沉積物中 Pb主要來源為鉛鋅礦和土壤母質(zhì),相對(duì)貢獻(xiàn)率分別為 20.00%~95.62%和4.38%~80.00%.
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Lead pollution and isotopic tracing in intertidal sediments of Jiulong River downstream.
LIN Cheng-qi, HU Gong-ren*, YU Rui-lian (Department of Environmental Science and Engineering, Huaqiao University, Xiamen 361021, China).
China Environmental Science, 2015,35(8):2503~2510
Lead isotopes have been widely applied to tracing lead sources in the environment. Lead concentration and isotopic compositions (206Pb/207Pb and208Pb/206Pb) of 23 intertidal surface sediments collected from Jiulong River downstream and surrounding known sources were analyzed to assess the spatial variation of lead, and to discuss the lead sources and their relative contributions using the dual member model and the three-end member model of lead isotopic ratios. The results show that the range of lead concentration in the intertidal surface sediments of Jiulong River downstream was 38.50~128.50mg/kg with the mean value of 80.60mg/kg. According to geoaccumulation index, enrichment factor and potential ecological risk index, the lead pollution degree was mild to moderate and the potential ecological risk of lead was mild in the sediments. The ranges of lead isotopic ratios of206Pb/207Pb and208Pb/206Pb are 1.1651~1.1924 and 1.9640~2.1071, respectively. Lead pollutants in most studied sediments mainly came from Fujian Pb-Zn deposit and parent soil material while seldom from vehicle exhaust. At the upstream of Jiulong River estuary, lead in the sediments were mainly from Pb-Zn deposit, parent soil material and coal, with the contribution rates of 26.74%~56.61%, 18.85%~19.91% and 24.20%~58.53%, respectively. At the outer end of Jiulong River estuary, lead were mainly from Pb-Zn deposit, parent soil material, coal and marine paints, with the contribution rates of 20.06%, 13.75%, 7.52% and 58.67%, respectively. At other sampling sites, the sediment lead mainly derives from Pb-Zn deposit and parent soil material with the contribution rates of 20.00%~95.62% and 4.38%~80.00%, respectively.
lead isotopes;Jiulong River downstream;sediment;source of pollution;contribution rate
X142
A
1000-6923(2015)08-2503-08
2014-11-28
國(guó)家自然科學(xué)基金項(xiàng)目(21077036,21177043)和福建省自然科學(xué)基金項(xiàng)目(2014J01159)
* 責(zé)任作者, 教授, grhu@hqu.edu.cn
林承奇(1991-),男,福建漳州人,華僑大學(xué)碩士研究生,研究方向?yàn)榄h(huán)境監(jiān)測(cè)與評(píng)價(jià).發(fā)表論文1篇.