自动顶空固相微萃取-气相色谱质谱联用法检测水中碘代三卤甲烷

碘代三卤甲烷(I-THMs)是一种未受控的新消毒副产物(DBPs),与其他卤代三卤甲烷比较具有低浓度、高毒性的特性。文章介绍了全自动顶空固相微萃取气相色谱联用质谱法检测饮用水和原水中6种I-THMs,萃取条件:以50/30DVB/CAR/PDMS为萃取头,萃取温度为50℃,萃取时间为25 min,振摇速度为400 r/min,解析温度为210℃,解析时间为1 min。该方法中各目标物检出限为4.2~11.0 ng/L,标准曲线为10~400 ng/L,各目标物线性相关系数均大于0.998,选择了50、100、200 ng/L 3个加标质量浓度,以纯水、出厂水和原水为本底进行了方法验证,相对标准偏差(RSD)为0.9%~7.3%,加标回收率为71%~118%,证明该固相微萃取-气相色谱质谱法能够精密准确地应用于出厂水及原水中痕量I-THMs的检测。利用该方法对上海市水厂的饮用水进行了检测,6种I-THMs除碘仿外都有检出,二氯一碘甲烷和溴氯碘甲烷的检出浓度较高。

Formation of Iodinated Trihalomethane Disinfection By-products by Co-oxidation of Natural Organic Matter with Sodium Hypochlorite and Lead Dioxide

Iodinated trihalomethanes(I-THMs)in drinking water pipelines have attracted wide attention due to their high toxicity.The coexistence of widely present lead dioxide(PbO_(2))with commonly used disinfectant sodium hypochlorite(NaClO)in drinking water might change the formation characteristics of I-THMs due to the strongly oxidizing properties of PbO_(2).This study investigated the formation of I-THMs during the co-oxidation of natural organic matter including humic acid(HA),extracellular organic matter(EOM),and intracellular organic matter(IOM)of algogenic organic matter by PbO_(2) and NaClO.Triiodomethane(CHI_(3))is the dominant product in the single oxidation system of PbO_(2),whereas trichloromethane(CHCl_(3)),chlorodiiodomethane(CHClI_(2)),and dichloroiodomethane(CHCl2I)are the major products in the single NaClO system.In the co-oxidation system,the dominant I-THMs are similar to those in the single NaClO system.However,the CHCl_(3) content decreased to 56.4%whereas I-THMs concentrations remained unchanged with the increase of PbO_(2) concentration.The main reason is attributed to the reduced residual chlorine content due to the reaction of PbO_(2) with NaClO.IOM is more prone to forming I-THMs than HA and EOM due to the specified structures.This study suggested that PbO_(2) in the drinking water supply pipelines might change the risk of THMs.

Formation of iodo-trihalomethanes, iodo-haloacetic acids, and haloacetaldehydes during chlorination and chloramination of iodine containing waters in laboratory controlled reactions

Iodine containing disinfection by-products（I-DBPs） and haloacetaldehydes（HALs） are emerging disinfection by-product（DBP） classes of concern. The former due to its increased potential toxicity and the latter because it was found to be the third most relevant DBP class in mass in a U.S. nationwide drinking water study. These DBP classes have been scarcely investigated, and this work was performed to further explore their formation in drinking water under chlorination and chloramination scenarios. In order to do this, iodo-trihalomethanes（I-THMs）,iodo-haloacetic acids（I-HAAs） and selected HALs（mono-HALs and di-HALs species, including iodoacetaldehyde） were investigated in DBP mixtures generated after chlorination and chloramination of different water matrices containing different levels of bromide and iodide in laboratory controlled reactions. Results confirmed the enhancement of I-DBP formation in the presence of monochloramine. While I-THMs and I-HAAs contributed almost equally to total I-DBP concentrations in chlorinated water, I-THMs contributed the most to total I-DBP levels in the case of chloraminated water. The most abundant and common I-THM species generated were bromochloroiodomethane, dichloroiodomethane, and chlorodiiodomethane. Iodoacetic acid and chloroiodoacetic acid contributed the most to the total I-HAA concentrations measured in the investigated disinfected water. As for the studied HALs, dihalogenated species were the compounds that predominantly formed under both investigated treatments.

太湖部分地区碘代三卤甲烷分布特征及其与藻类有机物的关系初探

藻类有机物(algal organic matter,AOM)被证实是碘代消毒副产物(iodinated disinfection by-products,I-DBPs)生成的前体有机物,然而真实环境中I-DBPs与AOM的关系还不明确.本文研究了太湖碘代三卤甲烷(iodinated trihalomethanes,I-THMs)的分布特征,并初步分析了地表水中I-THMs与AOM的关系.I-THMs在枯水期与丰水期平均浓度分别是655.9 ng·L^(-1)和134.6 ng·L^(-1).其中,CHBrI_2和CHI_3为主要的污染物,而CHCl_2I检出相对较低.皮尔森相关性分析表明,CHCl_2I、CHCl Br I、CHClI_2、CHI_3等I-THMs均与叶绿素a具有显著正相关性,而CHCl_2I、CHBr_2I、CHBrI_2、CHI_3与总磷TP、CHCl_2I、CHBr_2I与总氮TN均具有显著正相关性;CHCl_2I、CHClI_2与舟形藻(Navicula sp.)细胞浓度也具有显著正相关,但CHBrI_2等与微囊藻(Microcystis sp.),栅藻(Scenedesmus sp.)细胞浓度呈显著负相关(P<0.05).本研究间接表明,真实环境中AOM是I-THMs的一个重要来源.

Ca^(2+)对氯化体系中消毒副产物生成影响研究

Ca^(2+)作为天然水体中常见金属离子,参与饮用水处理和输配过程。为研究氯化消毒过程中Ca^(2+)对10种三卤甲烷(THMs)的生成情况和生物毒性的影响,以富里酸(FA)为底物,重点考察Ca^(2+)浓度和pH对其THMs生成的影响,并通过紫外可见差分光谱分析Ca^(2+)和FA的络合情况。实验结果表明,Ca^(2+)通过与FA络合促进NaClO的衰减,THMs生成量随着Ca^(2+)浓度增加呈先增大后减少的趋势。低浓度的Ca^(2+)对碘代三卤甲烷(I-THMs)、氯代和溴代三卤甲烷(THM;)的促进作用随pH的增大逐渐降低,且Ca^(2+)对I-THMs的促进作用明显高于THM;进一步提高Ca^(2+)浓度,可明显抑制THMs生成和降低THMs的细胞毒性。

Insight into the formation of iodinated tr ihalomethanes dur ing chlor ination,monochloramination, and dichloramination of iodide-containing water

In this study, the formation of iodinated trihalomethanes(I-THMs) was systematically evaluated and compared for three treatment processes-(i) chlorination,(ii) monochloramine, and(iii) dichloramination-under different p H conditions. The results demonstrated that ITHM formation decreased in the order of monochloramination > dichloramination > chlorination in acidic and neutral p H. However, the generation of I-THMs increased in the dichloramination < chlorination < monochloramination order in alkaline condition. Specifically, the formation of I-THMs increased as p H increased from 5 to 9 during chlorination and monochloramination processes, while the maximum I-THM formation occurred at pH 7 during dichloramination. The discrepancy could be mainly related to the stability of the three chlor(am) ine disinfectants at different p H conditions. Moreover, in order to gain a thorough insight into the mechanisms of I-THM formation during dichloramination, further investigation was conducted on the influencing factors of DOC concentration and Br/Imolar ratio. I-THM formation exhibited an increasing and then decreasing trend as the concentration of DOC increased from 1 to 7 mg-C/L, while the yield of I-THMs increased with increasing Br/Imolar ratio from 5:0 to 5:10. During the three processes mentioned above, similar I-THM formation results were also obtained in real water, which indicates that the excessive generation of I-THMs should be paid special attention during the disinfection of iodide-containing water.

固相微萃取气质联用同时测定饮用水中的卤乙腈、卤代硝基甲烷及含碘三卤甲烷消毒副产物

目的建立固相微萃取气相色谱质谱联用测定饮用水中6个卤乙腈、7个卤代硝基甲烷及5个含碘三卤甲烷消毒副产物的方法,并了解本市饮用水中目标消毒副产物的浓度水平。方法优化固相微萃取参数,建立检测方法,并对100个饮用水样品进行检测。结果选择DVB/PDMS萃取头,以氯化钠为盐析试剂且加入浓度为40%(W/V),在萃取温度40℃萃取时间20 min、解吸温度170℃解吸时间2 min的操作条件下,目标消毒副产物具有良好的检测灵敏度,检出限为0.14 ng/L^18.00 ng/L,方法的线性相关系数>0.99,加标回收率为70%~121%,相对标准偏差为1%~15%。对本市100个饮用水进行检测,结果卤乙腈、含碘三卤甲烷、卤代硝基甲烷的中位值浓度分别为0.86μg/L、0.36μg/L、0.07μg/L,检出率分别为99%、89%、89%。结论本方法灵敏、简便、无干扰,适合饮用水中痕量浓度水平的卤乙腈、卤代硝基甲烷、含碘三卤甲烷的检测。

吹扫捕集-气相色谱/质谱法测定饮用水中的10种三卤甲烷

目的建立饮用水中10种三卤甲烷的吹扫捕集-气相色谱/质谱检测方法。方法通过吹扫捕集,将目标化合物从水中吹脱,并用捕集阱同时吸附,热解吸后利用气相色谱分离,质谱检测,内标法定量。结果该方法三氯甲烷、二氯一溴甲烷、一氯二溴甲烷、三溴甲烷的线性范围为0.50μg/L^25μg/L,一氯一溴一碘甲烷、二氯一碘甲烷、二溴一碘甲烷、一氯二碘甲烷、一溴二碘甲烷、三碘甲烷的线性范围为0.050μg/L^2.5μg/L,线性相关系数均>0.998,检出限为0.5 ng/L^9.2 ng/L,加标回收率为89%~113%,相对标准偏差<5%。结论本文建立的方法简便、灵敏、准确,适合饮用水中常见三卤甲烷及含碘三卤甲烷的检测。

Relationships between regulated DBPs and emerging DBPs of health concern in U.S. drinking water

A survey was conducted at eight U.S. drinking water plants, that spanned a wide range of water qualities and treatment/disinfection practices. Plants that treated heavily-wastewaterimpacted source waters had lower trihalomethane to dihaloacetonitrile ratios due to the presence of more organic nitrogen and HAN precursors. As the bromide to total organic carbon ratio increased, there was more bromine incorporation into DBPs. This has been shown in other studies for THMs and selected emerging DBPs(HANs), whereas this study examined bromine incorporation for a wider group of emerging DBPs(haloacetaldehydes, halonitromethanes). Moreover, bromine incorporation into the emerging DBPs was, in general, similar to that of the THMs. Epidemiology studies that show an association between adverse health effects and brominated THMs may be due to the formation of brominated emerging DBPs of heath concern. Plants with higher free chlorine contact times before ammonia addition to form chloramines had less iodinated DBP formation in chloraminated distribution systems, where there was more oxidation of the iodide to iodate(a sink for the iodide) by the chlorine. This has been shown in many bench-scale studies(primarily for iodinated THMs), but seldom in full-scale studies(where this study also showed the impact on total organic iodine. Collectively, the THMs, haloacetic acids, and emerging DBPs accounted for a significant portion of the TOCl, TOBr, and TOI;however, ~50% of the TOCl and TOBr is still unknown. The correlation of the sum of detected DBPs with the TOCl and TOBr suggests that they can be used as reliable surrogates.

压载水中消毒副产物碘代三卤甲烷形成机制研究

由于海水中I^-、Br^-含量较高,通过电解法处理压载水过程中会产生一定含量的碘代三卤甲烷(ITHMs),该类物质具有极强的致癌和致突变特性,在电解处理工艺过程中极易生成,难以有效控制。本研究通过次氯酸钠投加模拟实验分析消毒副产物碘代三卤甲烷的形成机制与影响因素,结果显示:(1)Na Cl O浓度由5 mg/L增加至15 mg/L时,I-THMs生成量增加24.76μg/L;(2)I-THMs的生成量随着温度的升高而增加,当温度高于20℃时I-THMs的生成量增加迅速;(3)酸性条件下,I-THMs的生成量较小,碱性条件下,I-THMs的生成量明显增大;(4)对于溶液中不同溴碘浓度比,I-THMs的生成量和各组分比例差异较大。因此,建议在压载水电解处理工艺过程中应对反应条件进行最佳优化,以期保证其处理效果的同时有效控制消毒副产物DBPs的产生。