饮用水水质标准升级带来的消毒副产物挑战与对策

随着国家和地方饮用水水质标准提升,标准中增加了消毒副产物指标、提高了标准限值和检测频率。加之水源水中有机物浓度居高不下,使得消毒副产物成为我国供水行业面临的重要水质挑战。以三卤甲烷、卤乙酸、亚硝胺为代表,汇总了公开文献报道中我国典型城市饮用水中消毒副产物浓度。介绍了上述消毒副产物的前体物成分、来源和解析方法。基于中试和生产运行数据,提出了水源调控、厂内控制的消毒副产物控制策略。其中,强化混凝沉淀、增加臭氧-活性炭深度处理和优化消毒工艺是控制上述消毒副产物的关键处理工艺。

体外膜肺氧合救治危重症孕产妇的多学科协作护理

总结8例危重症孕产妇应用体外膜肺氧合救治的护理经验。护理要点:组建多学科协作团队;做好困难置管的配合与管理;分娩计划的落实与胎儿监测;精准抗凝及出血并发症的预防;清醒体外膜肺氧合期间加强管路固定及自主呼吸监测;多层面给予心理支持。本组8例患者均存活,胎儿3例存活.

人工智能的“认知转向”——通向通用人工智能的必由之路

人类智能是“通用智能”。人工智能要成为通用的,即通用人工智能,让其具有心理性的认知因素是必不可少的。这意味着“智能”不是“认知”,人工智能要转向人工认知,也就是让目前人工智能的“计算智能”和“感知智能”走向“认知智能”,这就是人工智能的“认知转向”。而“认知智能”作为“通用智能”,与人类智能一样是适应性表征系统,在适应性表征概念下,两种智能可统一起来进而成为通用的。然而,在通用人工智能能否实现的问题上,存在着两种对立的立场,即乐观派和悲观派。这是因为,其中蕴含了关于人工行为体的主体性、能动性和意向性问题的争论,而区分行为体和主体、行为体间性和主体间性、行为体的能动性与主体的主体性、行为体的指向性与主体的意向性是十分必要的。适应性表征被视为消解这些争论和弥合不同智能鸿沟的概念框架,进而成为实现机器意识的方法论策略。

Increase in Organochlorine Contaminant Levels in Major Water Sources of the United States in Response to the Coronavirus Pandemic

Organochlorine contaminants, such as triclosan (TCS), are present in major water sources across the United States. These antimicrobial compounds are widely used as multipurpose ingredients in everyday consumer products. They can be ingested or absorbed through the skin and are found in human blood, breast milk, and urine samples. Studies have shown that the increased use of antimicrobial agents leads to their presence and persistence in the ecosystem, particularly in soil and watersheds. Many studies have highlighted emerging concerns associated with the overuse of TCS, including dermal irritations, a higher incidence of antibacterial-related allergies, microbial resistance, disruptions in the endocrine system, altered thyroid hormone activity, metabolism, and tumor metastasis and growth. Organochlorine contaminant exposures play a role in inflammatory responsiveness, and any unwarranted innate response could lead to adverse outcomes. The capacity of TCS and other organochlorine contaminants to induce inflammation, resulting in persistent and chronic inflammation, is linked to various pathologies, such as cardiovascular disease and several types of cancers. Chronic inflammation presents a severe consequence of exposure to these antimicrobial agents, as any changes could result in the loss of immune competence. Organochlorine contaminant levels were established by the United States Environmental Protection Agency (EPA) in 2019-2020 and have consistently increased in response to the novel coronavirus (nCoV) (COVID-19) pandemic. Our previous research examined the overuse of products containing triclosan (TCS), which led to an increase in total trihalomethane (TTHM) levels affecting the quality of our water supply. We also investigated the impact of the FDA ban that now requires pre-market approval. To comprehend the consequences of excessive antimicrobial use on water quality, we conducted an analysis of the levels of total trichloromethane (chloroform), a byproduct of free chlorine added to TCS, in primary water sources in metropolitan areas across the United States in 2019-2020. We repeated this analysis after the peak of the COVID-19 pandemic in 2021-2022 to examine its correlation with organochlorine exposure. Our study found that the COVID-19 pandemic, along with the increased use of antimicrobial products, has significantly raised the levels of total trihalomethanes compared to those reported in water quality reports from 2019-2020, in contrast to the reports from 2021-2022.

量子安全多方计算协议研究进展

量子安全多方计算是量子信息技术与隐私保护计算技术相结合形成的新兴交叉领域,作为量子密码学的一个重要分支,在安全性、计算效率等方面有着经典安全多方计算所不能及的优点。量子安全多方求和(Quantum Secure Multi-party Summation,QSMS)作为量子安全多方计算的一个最基本运算过程,近年来获得了广泛的关注。本文梳理了近期QSMS协议的研究进展,根据协议所依据的基本原理进行了分类,并介绍了一些代表性协议的基本原理和典型特点。

包装饮用水微生物及消毒副产物的控制与平衡

在包装饮用水生产中,利用氯化手段灭菌消毒会产生三卤甲烷等有机消毒副产物,而采用二氧化氯会导致亚氯酸盐等无机消毒副产物增加;紫外线(UV)照射对水杀菌时会形成亚硝酸盐,产品中加臭氧抑菌将增加溴酸盐风险。文章重点讨论各消毒杀菌手段对水体成分的影响,研究消毒副产物之间的机理和转化关系;采用消毒剂精准投加且无残留冲洗、UV照射剂量控制及硝酸盐安全界限、缩小臭氧作用时间等工艺改进方法,从而降低消毒副产物的风险。对照欧盟控菌标准,从尊重与保护水的天然特性和全过程卫生控制出发,结合包装水工厂实操,适度消毒,平衡微生物控制与消毒副产物产生的关系。

顶空气相色谱法测定生活饮用水中三卤甲烷的方法研究

建立了顶空气相色谱法测定生活饮用水中三氯甲烷、二氯一溴甲烷、一氯二溴甲烷和三溴甲烷的方法。三氯甲烷、二氯一溴甲烷、一氯二溴甲烷和三溴甲烷的质量浓度在0~20μg/L范围内与相应的峰面积呈线性关系,相关性系数分别为0.999 5、0.999 9、0.999 8和0.999 8;检出限分别为0.007 3、0.043、0.004 0、0.008 7μg/L;最低检测质量浓度分别为0.022、0.013、0.012、0.026μg/L;回收率三氯甲烷为92.6%~105%,二氯一溴甲烷为99.3%~103%,一氯二溴甲烷为94.2%~101%,三溴甲烷为97.9%~100%。

顶空毛细管柱气相色谱法测定生活饮用水中的三卤甲烷

目的:建立顶空毛细管柱气相色谱法测定生活饮用水中三氯甲烷(Trichloromethane,TCM)、二氯一溴甲烷(Bromodichloromethane,BDCM)、一氯二溴甲烷(Dibromochloromethane,DBCM)和三溴甲烷(Tribromomethane,TBM)4种三卤甲烷(Trihalomethanes,THMs)含量的方法。方法:将密封且已加入水样的顶空瓶放入全自动顶空仪中,加热到设定温度,使饮用水中的4种THMs在气液两相中实现动态平衡,气体进入气相色谱仪经色谱柱分离后,进入电子捕获检测器检测,外标法定量。结果:TCM、BDCM、DBCM及TBM在各自浓度范围内线性关系良好,相关系数R≥0.999;方法检出限为0.00598~0.0227μg·L^(-1),回收率在72.3%~119.2%,相对标准偏差为1.7%~3.9%。结论:该方法操作便捷、结果准确可靠,适用于生活饮用水中三卤甲烷含量的测定。

气相色谱-质谱法对环境水体中三卤甲烷的测定方法研究

为了解决水体中三卤甲烷测定效率低、精度差的不足,提出了一种新的气相色谱-质谱法联合测定技术。在采集到待测样品后,将其转移到空瓶内,然后经过吹扫捕集除理后,把水体中的三卤甲烷脱出并使用捕集器将待测吸附,最后经过热解以后进入气相色谱柱分离、质谱检测器测定、外标法定量获取测定结果。根据实际应用表明,新测定方法的检出限为0.001~0.03μg/L,测定的相对标准偏差在0.95%~2.2%之间,具有较高的测试精度,能够满足5种三卤甲烷的同时测定。

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。

给水厂不同加氯方式对THMs生成量的影响

以苏州某给水厂深度处理出水(未加氯)为实验对象,考察消毒剂投加量、反应时间、反应温度等反应条件对出厂水余氯浓度和消毒副产物三卤甲烷(THMs)生成量的影响。试验目的在于模拟给水厂在清水池前后投加消毒剂,在此基础上探索适宜的消毒剂投加方案,能够在保障余氯的情况下进一步降低出厂水THMs生成量。综合对比结果表明,消毒剂的投加量越大、消毒剂接触时间越长和反应水温越高,THMs生成量越高。在同等加氯量下,投加浓度为10%和5%的次氯酸钠对THMs生成趋势无较大影响,而采用分段投加(清水池前、后加氯消毒)的方式能够达到降低THMs生成量的目的。采用10%次氯酸钠消毒剂时,后加氯量12 mg/L,补加氯量5 mg/L,是试验中THMs生成量最低的消毒剂投加组合。

Cancer risk assessment from exposure to trihalomethanes in tap water and swimming pool water

We investigated the concentration of trihalomethanes （THMs） in tap water and swimming pool water in the area of the Nakhon Path- om Municipality during the period April 2005-March 2006. The concentrations of total THMs, chloroform, bromodichloromethane, dibromochloromethane and bromoform in tap water were 12.70-41.74, 6.72-29.19, 1.12-11.75, 0.63-3.55 and 0.08-3.40 μg/L, respectively, whereas those in swimming pool water were 26.15-65.09, 9.50-36.97, 8.90-18.01, 5.19-22.78 and ND-6.56 μg/L, respectively. It implied that the concentration of THMs in swimming pool water was higher than those in tap water, particularly, brominated-THMs. Both tap water and swimming pool water contained concentrations of total THMs below the standards of the World Health Organization （WHO）, European Union （EU） and the United States Environmental Protection Agency （USEPA） phase Ⅰ, but 1 out of 60 tap water samples and 60 out of 72 swimming pool water samples contained those over the Standard of the USEPA phase Ⅱ. From the two cases of cancer risk assessment including Case Ⅰ Non-Swimmer and Case Ⅱ Swimmer, assessment of cancer risk of nonswimmers from exposure to THMs at the highest and the average concentrations was 4.43×10^-5 and 2.19×10^-5, respectively, which can be classified as acceptable risk according to the Standard of USEPA. Assessment of cancer risk of swimmers from exposure to THMs at the highest and the average concentrations was 1.47×10^-3 and 7.99×10^-4, respectively, which can be classified as unacceptable risk and needs to be improved. Risk of THMs exposure from swimming was 93.9%-94.2% of the total risk. Cancer risk of THMs concluded from various routes in descending order was： skin exposure while swimming, gastro-intestinal exposure from tap water intake, and skin exposure to tap water and gastro-intestinal exposure while swimming. Cancer risk from skin exposure while swimming was 94.18% of the total cancer risk.

Reduction of Trihalomethanes Forming Potential by Adsorption of Natural Organic Matter on Ionic Exchange Resins

In a sanitation process of drinking water, carbon from the organic matter reacts with chlorine, forming by-products, among which are trihalomethanes (THM). These substances are carriers of mutagenic and can-cerogenic potential and hence should be removed in drinking water treatment. Since the natural organic mat-ters are precursors of THM formation, their removal from the water decreases the concentration of THMs. The THM forming potential is the most reliable indicator in evaluation of organic matter removal during drinking water treatment processes. The results have shown that the reaction producing THMs follows sec-ond order kinetics. The second order rate constant ranged from 0.024 M-1s-1 to 0.065 M-1s-1 at 22 °C and pH = 8.2 for 96 hours. The removal of 78.4% of natural organic matter, by adsorption on anionic exchange res-ins, resulted in the THM forming potential reduction by 63.1%. Various fractions of natural organic matter differ in their reactivity with chlorine, which is important when it comes to selection of the adsorption me-dium in the drinking water treatment processes.

Formation of Trihalomethanes during Seawater Chlorination

The use of seawater for industrial cooling is a vital technology that poses some of the most profound environmental impact on the water quality in the Arabian Gulf. Biocide (chlorine) is added to the seawater to control biofouling of the cooling system. This added chlorine reacts with bromide and other chemicals naturally exist in the water to form a wide range of oxidants. Regrettably, reactions between the residual oxidants and natural organic matter in the water lead to formation of toxic halogenated organic compounds that have detrimental effects on the environment when they are discharged into the Gulf. This paper describes the formation of trihalomethanes (THMs) in seawater cooling systems. Results of kinetic experiments have shown that concentrations of THMs increased rapidly with time during the first half hour. Chlorination of seawater has shown significant increase in total THMs (TTHMs) and in bromoform concentrations. Rapid decrease of UV absorbance at 254 nm was also observed during seawater chlorination which is indicative of natural organic matter degradation into small organic molecules including THMs and other by-products. The increase in chlorine dose was accompanied with an increase in TTHMs and bromoform concentrations. Linear relationships between total chlorine concentration and both final TTHMs and bromoform concentrations were established. First order exponential decay and exponential associate functions were developed to correlate chlorine dose with formed THMs.

Trihalomethanes adsorption on activated carbon fiber

The mechanism of activated carbon fiber (ACF) adsorption trihalomethanes (THMs) was studied. It was found that ACF adsorption THMs was exothermic, the physico-adsorption principally, but not a complete monolayer adsorption. The adsorptive capacities of ACF increased as the four species of THMs became more hydrophobic, and as the chlorine atoms in CHCls were substituted by more bromine atoms. The result of fixed-bed reactor adsorption was fitted to that of isotherm experiments.

Effects of typical nitrogenous compounds on trihalomethanes formation and chlorine demand during drinking water chlorination

Glycine(Gly),cysteine(Cys),aspartic acid(Asp),leucine(Leu),lysine(Lys),and methyl amine(MA) were chosen as typical nitrogenous compounds,and the effects of them on trihalomethanes (THMs) formation and chlorine demand were performed on filtrated water. Results show that the nitrogenous compounds enhance THMs formation,and the increased levels are controlled by characteristics and the concentration of nitrogenous compounds. The increase in THMs formation follows the order of Asp(126 μg/L)>Cys(119 μg/L)>MA(106 μg/L)>Lys(97 μg/L)≈Gly(96 μg/L)>Leu(80 μg/L)(while nitrogenous compounds=1.0 mg/L,and background THMs=60 μg/L). The increase in chlorine demand is approximately proportionate to the content of nitrogenous compounds,which illustrates that the increase is mainly caused by the reaction of nitrogenous compounds with chlorine. And the increase in chlorine demand follows the order of Cys(27.8 mg/L)>Asp(22.6 mg/L)=Gly(22.6 mg/L)>Lys(21.6 mg/L)>MA(14.1 mg/L)>Leu(11.8 mg/L) (while nitrogenous compounds=1.0 mg/L,and background chorine demand=1.8 mg/L). The mechanisms of nitrogenous compounds enhancing THMs formation are summ the increase of chlorine demand raising THMs formation in reaction of NOM with chlorine,and the THMs formation in chlorination of nitrogenous compounds themselves.

The Effect of Trihalomethanes in Contaminating the Major Watersheds of Middle Tennessee

We have analyzed the contamination of the three major watersheds in Middle Tennessee (Middle Cumberland River Watershed, Stones River Watershed, and Harpeth River Watershed) by trihalomethanes, such as chloroform, bromodichloromethane, dibromochloromethane, and bromoform. These chemicals play an important role in the develop-ment of cancer and adverse reproductive outcomes, and were found to be present above the threshold established by the Environmental Protection Agency. Certain portions of each watershed were found to be contaminated by the trihalomethanes, and deemed un-healthy. The household incomes in the major areas in the three watershed regions were also examined to determine a possible relationship with the level of water contamination. We concluded that income did not necessarily relate to water quality. Specific areas within each watershed that had lower average household incomes were found to have a higher concentration of the trihalomethanes in their drinking water, while other high-income areas were also affected by unhealthy water. However, these effects were random, and the level of contamination remained below the guidelines regulated by the State of Tennessee.

Characteristics of Trihalomethanes in Water Distribution System

To investigate the characteristics of disinfection by-products （DBPs） in an actual water distribution system using the raw water with high bromide ion concentration, the composition and concentration of trihalomethanes （THMs） formed by chlorination of the water in the presence of bromide ion were measured in a city water distribution system during one year. The results show that brominated THMs contributed a great part （83%-89% ） to the index for additive toxicity （ATI） and resulted in the ATI of most of the samples exceeding WHO guideline standard for total THMs （ TTHMs）, especially during the summer （ rainy season）. This indicates that the chlorination of water in the presence of bromide ion leaded to high ratios of brominated THMs to TrHMs. However, a visible increase in the concentration of THMs with increasing residence time in the distribution system was not observed. Additionally, based on alternatives analysis, packed tower aeration method is proposed to reduce THMs level of the finished water leaving the treatment plant.

Using prechloramination to control trihalomethanes formation in River Huang water with high bromide

An effective technology in controlling trihalomethanes （THMs） formation in the case of large amounts of bromide presenting was proposed, and the water of River Huang seriously polluted by bromide in winter in Tianjin City was studied. The THMs formation characteristics during prechloramination using preformed chloramines and converted chloramines were studied through jar tests. Results show that, in prechloramination process, the formation of THMs by preformed chloramines is very few, while that by converted ehloramines is a little higher. And the formation of THMs, especially Br^- substituted THMs, increases with the increase of time and Cl2：N ratio as well as the decrease of pH. The result obtained in a pilot plant shows that compared with prechlorination, the prechloramination process can efficiently control the formation of THMs, especially the Br^- substituted species. With equal chlorine dosage, the prechloramination can maintain a larger chlorine residue which offece, a larger CT value than prechlorination.

Trihalomethanes in Comerio Drinking Water and Their Reduction by Nanostructured Materials

The formation of disinfection by-products (DBPs) during chlorination of drinking water is an issue which has drawn significant scientific attention due to the possible adverse effects that these compounds have on human health and the formation of another DBPs. Factors that affect the formation of DBPs include: chlorine dose and residue, contact time, temperature, pH and natural organic matter (NOM). The most frequently detected DBPs in drinking water are trihalomethanes (THMs) and haloacetic acids (HAAs). The MCLs are standards established by the United States Environmental Protection Agency (USEPA) for drinking water quality established in Stage 1, Disinfectants and Disinfection Byproducts Rule (DBPR), and they limit the amount of potentially hazardous substances that are allowed in drinking water. The water quality data for THMs were evaluated in the Puerto Rico Aqueduct and Sewer Authority (PRASA). During this evaluation, the THMs exceeded the maximum contamination limit (MCLs) for the Comerio Water Treatment Plant (CWTP). USEPA classified the THMs as Group B2 carcinogens (shown to cause cancer in laboratory animals). This research evaluated the THMs concentrations in the following sampling sites: CWTP, Río Hondo and Pinas Abajo schools, Comerio Health Center (CDT), and the Vázquez Ortiz family, in the municipality of Comerio Puerto Rcio. The results show that the factors affecting the formation of THMs occur in different concentrations across the distribution line. There are not specific ranges to determine the formation of THMs in drinking water when the chemical and physical parameters were evaluated. Three different nanostructured materials (graphene, mordenite (MOR) and multiwalled carbon nanotubes (MWCNTs)) were used in this research, to reduce the THMs formation by adsorption in specific contact times. The results showed that graphene is the best nanomaterial to reduce THMs in drinking water. Graphene can reduce 80 parts per billion (ppb) of THMs in about 2 hours. In addition mordenite can reduce approximately 80 ppb of THMs and MWCNTs adsorbs 71 ppb of THMs in the same period of time respectively. In order to complement the adsorption results previously obtained, total organic carbon (TOC) analyses were measured, after different contact times with the nanomaterials. During the first 30 minutes, graphene C/Co was reduced to c.a. 0.9, in presence of each THMs solution. MWCNTs and MOR show similar adsorptions trends in comparison with graphene.