本文主要研究内容
作者徐勤勤(2019)在《汞和有机磷酸酯在三峡库区水、土/沉积物中的分布与鱼体富集特征》一文中研究指出:汞(Hg)和有机磷酸酯(OPEs)都具有很强的生物毒性,易挥发扩散,但在自然环境中不易分解,在食物链中具有富集效应。Hg和OPEs一旦进入水环境,易在鱼体中富集,其富集因子(Bioaccumulation factors,BAFs)可高达106107,食用Hg和OPEs污染的鱼类会对人体健康造成严重危害。因此,开展水环境中Hg和OPEs分布与鱼体富集特征调查及其风险评估具有重要的现实意义。三峡水库是目前我国最大的特大型水库,由于其特殊的“冬蓄夏泄”年调度方式,在每年的4-9月,三峡库区沿线会形成一条长557.8 km,面积349 km2,高差30 m的消落带。消落带作为库区流域中水陆相互作用的交错带,是库区径流的汇集地带,自然也易成为环境污染物的汇集区。另一方面,三峡库区地处人为活动密集区域,生态环境较为脆弱。开展污染物环境生物地球化学行为的研究对保护三峡库区生态环境至关重要。为此,本文选择无机的Hg和有机的OPEs两类对水环境影响较大的污染物为研究对象,以三峡库区重庆段位于长江干流的涪陵珍溪、忠县石宝寨和处在水库支流的开县汉丰湖/渠口、忠县涂井为代表性研究地点,从调查(按季节)三峡库区水体(深度:表层、10 m、30 m和50 m)和土壤/沉积物(水位高程:>175 m、165 m、155 m、145 m和全淹;深度:05cm、510 cm、1020 cm和>20 cm)Hg和OPEs的含量水平和分布特征出发,进一步探究Hg和OPEs在鱼体以及随营养级生物富集和生物放大的特征,并评价其对三峡库区可能带来的生态风险。研究结果如下:(1)三峡库区水体总汞(Total mercury,THg)浓度为8.71±4.17 ng L-1,显著低于我国地表水环境质量标准(50 ng L-1);甲基汞(Methylmercury,MeHg)浓度为0.37±0.32 ng L-1,浓度变化表现为暖季(夏季和秋季)大于冷季(春季和冬季)、干流(S1和S2)大于支流(S3和S4)的趋势,且不同形态Hg浓度随水深的增加而增高(除RHg外)。三峡库区水体∑10OPEs(溶解相+颗粒相)的平均浓度为289±158ng L-1(108865 ng L-1),磷酸三(2,氯乙基)酯(TCEP)、磷酸三(1,3-二氯异丙)酯(TDCP)、磷酸三(2-氯丙基)酯(TCPP)、磷酸三丁酯(TNBP)和磷酸三异丁酯(TIBP)是最主要的污染单体,各采样点间无显著的差异(p>0.74);水体中的OPEs主要存在于溶解相中,其LogKp值主要集中在1.844.87之间,且LogKow和LogKoc之间并没有表现出显著的相关关系(R2=0.04,p=0.28)。(2)三峡库区土壤/沉积物THg和MeHg的含量分别为51.3±35.6 ng g-1和0.34±0.27ng g-1,THg高于我国土壤汞背景值(38.0 ng g-1)但MeHg水平较低,且都无显著季节性差异(p>0.05);THg含量随土壤深度的加深而增高,而MeHg含量随土壤深度的加深而减小的趋势(除>175 m土壤);水位变化和有机质(Soil organic matter,SOM)含量都是影响土壤/沉积物Hg分布的一个重要因素。土壤/沉积物∑10OPEs的平均含量为205±135 ng g-1(16.3553 ng g-1),其主要污染单体为TDCP(40.7%)、TCPP(14.2%)、TIBP(13.0%)、磷酸三苯酯(TPHP,11.6%)和乙基己基二苯基磷酸酯(EHDPP,10.1%),但无明显的地点差异(p>0.05)。土壤中OPEs的浓度随水位高程的分布表现为未淹没土壤(>175 m)中OPEs含量较低,而水位波动的消落带土壤OPEs含量水平较高,说明消落带水位变化对OPEs的分布有重要影响;并且除TCEP(r=0.296,p<0.05)、磷酸三丙酯(TPRP,r=0.234,p<0.05)、TNBP(r=0.241,p<0.05)和TIBP(r=0.295,p<0.05)外,其它OPEs单体、∑10OPEs与SOM间无显著相关性(p>0.05),说明SOM不是影响三峡库区OPEs分布的主要因素。(3)三峡库区鱼体THg和MeHg含量的平均值分别为54 ng g-1(0.50272 ng g-1)和23 ng g-1(0.10199 ng g-1),远低于世界卫生组织(WHO)的最大允许摄入限值(THg,500 ng g-1,w.w.)和US-EPA质量控制标准(MeHg,300 ng g-1,w.w.),且表现为肉食性鱼类高于非肉食性鱼类;大多数同类鱼样Hg的富集与其大小无显著的相关性,其原因可能是:1)三峡库区蓄水以后大量增加的陆生营养物质;2)鱼汞富集过程中存在“生长稀释”现象,但需要进一步证实。鱼体肌肉样品∑10OPEs浓度为812±490 ng g-1(45.22887 ng g-1),其中TCEP(203±176 ng g-1)、TDCP(153±123 ng g-1)、TNBP(336±227 ng g-1)和TPHP(122±152 ng g-1)是主要的污染单体,其中TCEP、TDCP、TNBP、Cl-OPEs(氯代有机磷酸酯)、Alkyl-OPEs(烷基类有机磷酸酯)及∑10OPEs的中值含量表现为随营养级升高而增高的趋势;且鱼体∑10OPEs和OPEs单体浓度都与鱼体大小无显著相关性(p>0.05),这暗示OPEs在鱼体中存在代谢途径,因此降低了随着鱼类生长而产生的生物放大效应。(4)三峡库区鱼类肌肉THg和MeHg的LogBAF值分别为3.89(2.044.76)和4.83(2.51-6.11),且随着营养级的升高而增高;各单体TCEP、TDCP、TCPP、TNBP、TIBP、磷酸三乙基己基酯(TEHP)、磷酸三(2-丁氧基)乙酯(TBOEP)、EHDPP和TPHP的LogBAF值的分别为3.34(1.994.07)、3.59(2.224.43)、2.56(2.562.56)、3.94(2.814.61)、3.37(1.664.43)、3.05(2.463.52)、3.23(2.293.90)、4.51(3.795.22)和4.05(2.745.40),其中除TPHP、TBOEP、Aryl-OPEs外,其它OPEs单体和∑10OPEs的LogBAF中值均随营养级的增高而增高。鱼体LogBAF与LogKow之间没有统计意义上的相关性,但当OPEs单体LogKow<7,其LogBAF随着LogKow值的增大大致呈现增长趋势,并且LogBAF与Log Kow之间也存在显著的相关性(R2=0.52,p<0.05)。鱼体肌肉(n=71)的δ13C组成范围为-26.45-17.24‰,随营养级无明显趋势;δ15N范围为5.7215.34‰,随营养级增高而增高;但δ13C值与δ15N值呈现出显著的负相关关系(R2=0.30,p<0.01),说明不同营养级的鱼体食物来源变化很大,且表现出一定程度的富集效应。营养级位置(Trophic position,TP)变化范围为2.83(1.21-4.04),说明三峡库区食物链较短。鱼体肌肉THg、MeHg和IHg的营养级放大因子(TMFs)值分别为0.09、0.11和0.09,处于较低水平;而6种主要OPEs污染单体(检测率>50%)和∑10OPEs的浓度水平都与其δ15N值无显著性关系(p>0.05),说明鱼体OPEs没有随着营养级生物放大。(5)本次研究发现,在19862015期间三峡库区鱼体肌肉THg和MeHg的含量没有明显的增长趋势,表明三峡库区蓄水初期并没有出现显著的“水库效应”,其原因大致为:1)水体较低的溶解性有机碳(Dissolved organic carbon,DOC)和较高的pH,不利于甲基化反应;2)淹没土壤SOM含量较低且甲基化活动相对微弱;3)淹没植物降解速率较低,释放到水体的Hg和营养物质较少,同时淹没而未分解的植物还到吸收和固定汞的作用;4)库区食物链结构简单,且Hg的TMFs也较低。尽管库区鱼体THg和MeHg的含量水平很低,但是对于高频率摄食鱼肉的周边渔民而言,也可能存在Hg暴露风险。此外,本研究采用风险系数值(RQ)来评估水中OPEs对水生生物的危害,结果表明三峡库区主要OPEs污染单体TCEP、TDCP、TCPP、TNBP和TIBP的风险系数均小于0.1,没有毒性风险;采用每日摄入量(DI)来研究鱼体中OPEs的含量水平对人类身体健康的危害,结果显示,TCEP、TDCP、TNBP、TIBP、TPHP和TBOEP的每日摄入量均远小于每日参考剂量(RfD);并且TCEP(0.00000.0095)、TDCP(0.00000.0113)、TNBP(0.00000.0125)和TPHP(0.00000.0045)的RQ值范围均远远小于1,表明三峡库区鱼体OPEs没有暴露风险。
Abstract
gong (Hg)he you ji lin suan zhi (OPEs)dou ju you hen jiang de sheng wu du xing ,yi hui fa kuo san ,dan zai zi ran huan jing zhong bu yi fen jie ,zai shi wu lian zhong ju you fu ji xiao ying 。Hghe OPEsyi dan jin ru shui huan jing ,yi zai yu ti zhong fu ji ,ji fu ji yin zi (Bioaccumulation factors,BAFs)ke gao da 106107,shi yong Hghe OPEswu ran de yu lei hui dui ren ti jian kang zao cheng yan chong wei hai 。yin ci ,kai zhan shui huan jing zhong Hghe OPEsfen bu yu yu ti fu ji te zheng diao cha ji ji feng xian ping gu ju you chong yao de xian shi yi yi 。san xia shui ku shi mu qian wo guo zui da de te da xing shui ku ,you yu ji te shu de “dong xu xia xie ”nian diao du fang shi ,zai mei nian de 4-9yue ,san xia ku ou yan xian hui xing cheng yi tiao chang 557.8 km,mian ji 349 km2,gao cha 30 mde xiao la dai 。xiao la dai zuo wei ku ou liu yu zhong shui liu xiang hu zuo yong de jiao cuo dai ,shi ku ou jing liu de hui ji de dai ,zi ran ye yi cheng wei huan jing wu ran wu de hui ji ou 。ling yi fang mian ,san xia ku ou de chu ren wei huo dong mi ji ou yu ,sheng tai huan jing jiao wei cui ruo 。kai zhan wu ran wu huan jing sheng wu de qiu hua xue hang wei de yan jiu dui bao hu san xia ku ou sheng tai huan jing zhi guan chong yao 。wei ci ,ben wen shua ze mo ji de Hghe you ji de OPEsliang lei dui shui huan jing ying xiang jiao da de wu ran wu wei yan jiu dui xiang ,yi san xia ku ou chong qing duan wei yu chang jiang gan liu de fu ling zhen xi 、zhong xian dan bao zhai he chu zai shui ku zhi liu de kai xian han feng hu /qu kou 、zhong xian tu jing wei dai biao xing yan jiu de dian ,cong diao cha (an ji jie )san xia ku ou shui ti (shen du :biao ceng 、10 m、30 mhe 50 m)he tu rang /chen ji wu (shui wei gao cheng :>175 m、165 m、155 m、145 mhe quan yan ;shen du :05cm、510 cm、1020 cmhe >20 cm)Hghe OPEsde han liang shui ping he fen bu te zheng chu fa ,jin yi bu tan jiu Hghe OPEszai yu ti yi ji sui ying yang ji sheng wu fu ji he sheng wu fang da de te zheng ,bing ping jia ji dui san xia ku ou ke neng dai lai de sheng tai feng xian 。yan jiu jie guo ru xia :(1)san xia ku ou shui ti zong gong (Total mercury,THg)nong du wei 8.71±4.17 ng L-1,xian zhe di yu wo guo de biao shui huan jing zhi liang biao zhun (50 ng L-1);jia ji gong (Methylmercury,MeHg)nong du wei 0.37±0.32 ng L-1,nong du bian hua biao xian wei nuan ji (xia ji he qiu ji )da yu leng ji (chun ji he dong ji )、gan liu (S1he S2)da yu zhi liu (S3he S4)de qu shi ,ju bu tong xing tai Hgnong du sui shui shen de zeng jia er zeng gao (chu RHgwai )。san xia ku ou shui ti ∑10OPEs(rong jie xiang +ke li xiang )de ping jun nong du wei 289±158ng L-1(108865 ng L-1),lin suan san (2,lv yi ji )zhi (TCEP)、lin suan san (1,3-er lv yi bing )zhi (TDCP)、lin suan san (2-lv bing ji )zhi (TCPP)、lin suan san ding zhi (TNBP)he lin suan san yi ding zhi (TIBP)shi zui zhu yao de wu ran chan ti ,ge cai yang dian jian mo xian zhe de cha yi (p>0.74);shui ti zhong de OPEszhu yao cun zai yu rong jie xiang zhong ,ji LogKpzhi zhu yao ji zhong zai 1.844.87zhi jian ,ju LogKowhe LogKoczhi jian bing mei you biao xian chu xian zhe de xiang guan guan ji (R2=0.04,p=0.28)。(2)san xia ku ou tu rang /chen ji wu THghe MeHgde han liang fen bie wei 51.3±35.6 ng g-1he 0.34±0.27ng g-1,THggao yu wo guo tu rang gong bei jing zhi (38.0 ng g-1)dan MeHgshui ping jiao di ,ju dou mo xian zhe ji jie xing cha yi (p>0.05);THghan liang sui tu rang shen du de jia shen er zeng gao ,er MeHghan liang sui tu rang shen du de jia shen er jian xiao de qu shi (chu >175 mtu rang );shui wei bian hua he you ji zhi (Soil organic matter,SOM)han liang dou shi ying xiang tu rang /chen ji wu Hgfen bu de yi ge chong yao yin su 。tu rang /chen ji wu ∑10OPEsde ping jun han liang wei 205±135 ng g-1(16.3553 ng g-1),ji zhu yao wu ran chan ti wei TDCP(40.7%)、TCPP(14.2%)、TIBP(13.0%)、lin suan san ben zhi (TPHP,11.6%)he yi ji ji ji er ben ji lin suan zhi (EHDPP,10.1%),dan mo ming xian de de dian cha yi (p>0.05)。tu rang zhong OPEsde nong du sui shui wei gao cheng de fen bu biao xian wei wei yan mei tu rang (>175 m)zhong OPEshan liang jiao di ,er shui wei bo dong de xiao la dai tu rang OPEshan liang shui ping jiao gao ,shui ming xiao la dai shui wei bian hua dui OPEsde fen bu you chong yao ying xiang ;bing ju chu TCEP(r=0.296,p<0.05)、lin suan san bing zhi (TPRP,r=0.234,p<0.05)、TNBP(r=0.241,p<0.05)he TIBP(r=0.295,p<0.05)wai ,ji ta OPEschan ti 、∑10OPEsyu SOMjian mo xian zhe xiang guan xing (p>0.05),shui ming SOMbu shi ying xiang san xia ku ou OPEsfen bu de zhu yao yin su 。(3)san xia ku ou yu ti THghe MeHghan liang de ping jun zhi fen bie wei 54 ng g-1(0.50272 ng g-1)he 23 ng g-1(0.10199 ng g-1),yuan di yu shi jie wei sheng zu zhi (WHO)de zui da yun hu she ru xian zhi (THg,500 ng g-1,w.w.)he US-EPAzhi liang kong zhi biao zhun (MeHg,300 ng g-1,w.w.),ju biao xian wei rou shi xing yu lei gao yu fei rou shi xing yu lei ;da duo shu tong lei yu yang Hgde fu ji yu ji da xiao mo xian zhe de xiang guan xing ,ji yuan yin ke neng shi :1)san xia ku ou xu shui yi hou da liang zeng jia de liu sheng ying yang wu zhi ;2)yu gong fu ji guo cheng zhong cun zai “sheng chang xi shi ”xian xiang ,dan xu yao jin yi bu zheng shi 。yu ti ji rou yang pin ∑10OPEsnong du wei 812±490 ng g-1(45.22887 ng g-1),ji zhong TCEP(203±176 ng g-1)、TDCP(153±123 ng g-1)、TNBP(336±227 ng g-1)he TPHP(122±152 ng g-1)shi zhu yao de wu ran chan ti ,ji zhong TCEP、TDCP、TNBP、Cl-OPEs(lv dai you ji lin suan zhi )、Alkyl-OPEs(wan ji lei you ji lin suan zhi )ji ∑10OPEsde zhong zhi han liang biao xian wei sui ying yang ji sheng gao er zeng gao de qu shi ;ju yu ti ∑10OPEshe OPEschan ti nong du dou yu yu ti da xiao mo xian zhe xiang guan xing (p>0.05),zhe an shi OPEszai yu ti zhong cun zai dai xie tu jing ,yin ci jiang di le sui zhao yu lei sheng chang er chan sheng de sheng wu fang da xiao ying 。(4)san xia ku ou yu lei ji rou THghe MeHgde LogBAFzhi fen bie wei 3.89(2.044.76)he 4.83(2.51-6.11),ju sui zhao ying yang ji de sheng gao er zeng gao ;ge chan ti TCEP、TDCP、TCPP、TNBP、TIBP、lin suan san yi ji ji ji zhi (TEHP)、lin suan san (2-ding yang ji )yi zhi (TBOEP)、EHDPPhe TPHPde LogBAFzhi de fen bie wei 3.34(1.994.07)、3.59(2.224.43)、2.56(2.562.56)、3.94(2.814.61)、3.37(1.664.43)、3.05(2.463.52)、3.23(2.293.90)、4.51(3.795.22)he 4.05(2.745.40),ji zhong chu TPHP、TBOEP、Aryl-OPEswai ,ji ta OPEschan ti he ∑10OPEsde LogBAFzhong zhi jun sui ying yang ji de zeng gao er zeng gao 。yu ti LogBAFyu LogKowzhi jian mei you tong ji yi yi shang de xiang guan xing ,dan dang OPEschan ti LogKow<7,ji LogBAFsui zhao LogKowzhi de zeng da da zhi cheng xian zeng chang qu shi ,bing ju LogBAFyu Log Kowzhi jian ye cun zai xian zhe de xiang guan xing (R2=0.52,p<0.05)。yu ti ji rou (n=71)de δ13Czu cheng fan wei wei -26.45-17.24‰,sui ying yang ji mo ming xian qu shi ;δ15Nfan wei wei 5.7215.34‰,sui ying yang ji zeng gao er zeng gao ;dan δ13Czhi yu δ15Nzhi cheng xian chu xian zhe de fu xiang guan guan ji (R2=0.30,p<0.01),shui ming bu tong ying yang ji de yu ti shi wu lai yuan bian hua hen da ,ju biao xian chu yi ding cheng du de fu ji xiao ying 。ying yang ji wei zhi (Trophic position,TP)bian hua fan wei wei 2.83(1.21-4.04),shui ming san xia ku ou shi wu lian jiao duan 。yu ti ji rou THg、MeHghe IHgde ying yang ji fang da yin zi (TMFs)zhi fen bie wei 0.09、0.11he 0.09,chu yu jiao di shui ping ;er 6chong zhu yao OPEswu ran chan ti (jian ce lv >50%)he ∑10OPEsde nong du shui ping dou yu ji δ15Nzhi mo xian zhe xing guan ji (p>0.05),shui ming yu ti OPEsmei you sui zhao ying yang ji sheng wu fang da 。(5)ben ci yan jiu fa xian ,zai 19862015ji jian san xia ku ou yu ti ji rou THghe MeHgde han liang mei you ming xian de zeng chang qu shi ,biao ming san xia ku ou xu shui chu ji bing mei you chu xian xian zhe de “shui ku xiao ying ”,ji yuan yin da zhi wei :1)shui ti jiao di de rong jie xing you ji tan (Dissolved organic carbon,DOC)he jiao gao de pH,bu li yu jia ji hua fan ying ;2)yan mei tu rang SOMhan liang jiao di ju jia ji hua huo dong xiang dui wei ruo ;3)yan mei zhi wu jiang jie su lv jiao di ,shi fang dao shui ti de Hghe ying yang wu zhi jiao shao ,tong shi yan mei er wei fen jie de zhi wu hai dao xi shou he gu ding gong de zuo yong ;4)ku ou shi wu lian jie gou jian chan ,ju Hgde TMFsye jiao di 。jin guan ku ou yu ti THghe MeHgde han liang shui ping hen di ,dan shi dui yu gao pin lv she shi yu rou de zhou bian yu min er yan ,ye ke neng cun zai Hgbao lou feng xian 。ci wai ,ben yan jiu cai yong feng xian ji shu zhi (RQ)lai ping gu shui zhong OPEsdui shui sheng sheng wu de wei hai ,jie guo biao ming san xia ku ou zhu yao OPEswu ran chan ti TCEP、TDCP、TCPP、TNBPhe TIBPde feng xian ji shu jun xiao yu 0.1,mei you du xing feng xian ;cai yong mei ri she ru liang (DI)lai yan jiu yu ti zhong OPEsde han liang shui ping dui ren lei shen ti jian kang de wei hai ,jie guo xian shi ,TCEP、TDCP、TNBP、TIBP、TPHPhe TBOEPde mei ri she ru liang jun yuan xiao yu mei ri can kao ji liang (RfD);bing ju TCEP(0.00000.0095)、TDCP(0.00000.0113)、TNBP(0.00000.0125)he TPHP(0.00000.0045)de RQzhi fan wei jun yuan yuan xiao yu 1,biao ming san xia ku ou yu ti OPEsmei you bao lou feng xian 。
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