饮用水中交链孢霉毒素氯消毒副产物鉴定及其毒性作用评价

目的 研究水中交链孢菌酮酸(TeA)和腾毒素(TEN)在氯消毒过程中的反应动力学特征,对产生的氯消毒副产物(DBPs)进行结构鉴定,并对其消毒副产物的细胞毒性进行初步探索。方法 本研究通过实验室模拟其消毒反应过程,研究其反应动力学特征,利用超高效液相色谱-串联四级杆飞行时间质谱(UPLC-Q-TOF/MS)和核磁共振波谱对反应产物进行结构鉴定并初步评价其毒性。结果 TeA氯消毒反应可生成2种氯消毒副产物DBP-188和DBP-240,而TEN氯代反应很慢未观察到氯消毒副产物的产生。反应动力学试验表明TEN与氯的反应速率随着反应体系中氯浓度和pH值的增加而升高。体外毒性预测分析发现TeA的氯消毒副产物经口毒性、发育毒性和致癌性均高于母体。结论 交链孢霉毒素经过氯消毒会产生氯消毒副产物,反应过程受pH值与氯浓度的影响,氯消毒副产物的预测毒性高于母体,细胞试验证明了TeA氯消毒副产物具有一定的细胞毒性。     

Presence of Trihalomethanes in ready-to-eat vegetables disinfected with chlorine

ABSTRACT

Trihalomethanes (THMs) – CHCl₃, CHCl₂Br, CHClBr₂ and CHBr₃ – are drinking water disinfection by-products (DBPs). These compounds can also be absorbed by different types of foods, including ready-to-eat (RTE) fresh vegetables. The potential absorption of THMs during washing of RTE vegetables could pose a potential risk to consumers’ health. The concentration of THMs in the water used in the manufacturing process of these products shall not exceed the limit of 100 or 80 µgL^?1 according to European Union (EU) and United States legislation, respectively. By contrast, there is little information about the presence of such compounds in the final product. This study evaluated the concentration of THMs in different types of RTE vegetables (carrots, iceberg lettuce, lettuce, mixed salad, parsley, parsley and garlic, rocket salad, valerian) after washing with chlorinated water. In the 115 samples analysed, the average value of total THMs was equal to 76.7 ng g^?1. Chloroform was the THM present in the largest percentage in all the RTE vegetables. These results show that the process of washing RTE vegetables should be optimised in order to reduce the risk for consumers associated with the presence of DBPs.     

离子色谱法测定饮用水中5种阴离子及3种消毒副产物

建立一种同时快速测定饮用水中F-、Cl-、NO2-、NO3-、SO42-5种阴离子及Cl O2-、Br O3-、Cl O3-3种消毒副产物的离子色谱方法。测定中采用Metrohm A Supp 5 250+A Supp 1 Guard组合分离柱对上述5种阴离子及3种消毒副产物进行分离。试验结果表明,该方法相关性好、精密度高、无干扰、操作简单、分析速度快。     

亚硝酸盐-紫外吸收光谱法测定水中的游离氯

目的 研究亚硝酸盐-紫外光谱法测定生活饮用水中游离氯含量的分析方法.方法 向含游离氯的水样管中加入1.0 ml亚硝酸钠溶液(ρ=5 g/L)作用30 min,依次加入1.0 ml氨基磺酸溶液(ρ=10 g/L)和1.0 ml盐酸(c=1.0 mol/L)制备样品溶液,以硝酸盐氮标准溶液制备标准溶液,在220 nm波长下同时测定样品管和标准管的吸光度值,并以此计算出水样中游离氯的含量.结果 亚硝酸钠将水中的游离氯定量地还原成了硝酸盐,其生成的量与游离氯的含量成正比(r=0.999 8),并呈等摩尔关系.方法中加入的氨基磺酸消除了过量的亚硝酸盐对测定结果的影响.在室温下,可直接取澄清水样按本法检测水中游离氯的含量.本法灵敏度为:0.05 mg/L,RSD为1.43％～10.00％,回收率为94.23％～103.20％.结论 本法可用于测定生活饮用水中的游离氯的含量.     

中压紫外线技术在包装饮用水中的杀菌应用

铜绿假单胞菌,又名绿脓杆菌,因其可产生多种外毒素、内毒素等致病因子,是导致急性肠道疾病和皮肤炎症的完全致病菌,故成为包装饮用水检测中一项非常重要的指标。鉴于铜绿假单胞菌的致病性,《食品安全国家标准包装饮用水》(GB 19298-2014)明确规定,每250mL水样中铜绿假单胞菌不得检出,并要求出厂前对每批次成品包装饮用水进行铜绿假单胞菌检测,若检出该物质,则为不合格产品,必须召回且停止销售。     

Free available chlorine in commercial broiler chicken drinking water in New Zealand

Free available chlorine (FAC) concentrations in drinking water supplied to broiler chickens grown commercially in New Zealand were monitored for 11 farms in two companies. Different sites within a growout house were examined at different times of the day to determine spatial and temporal differences in FAC concentrations. Taps provided water with significantly higher FAC concentrations than did drinkers. There were no significant differences between the concentrations of FAC taken from various drinkers around the growout house. There were differences in the variations of measurements taken from the same drinker within a growout house at different times of the day, with variations increasing in the afternoon. No growout houses provided an average FAC content of 2 ppm, the suggested standard in one company. Three growout houses consistently met the chlorine concentration of 0.2 ppm suggested by the New Zealand Drinking Water Standards.     

毛细管区带电泳-间接紫外检测法测定饮用水中5种阴离子

目的建立毛细管区带电泳-间接紫外检测法测定饮用水中5种阴离子的新方法。方法样品无需滤膜过滤可直接进样。用未涂覆熔融石英毛细管(75μm×80 cm,有效长度为70 cm)作为分离柱。以20 mmol/L邻苯二甲酸、100 mmol/L二乙醇胺和0.5 mmol/L十六烷基三甲基溴化铵为分离缓冲体系。结果 Cl~-、NO_3~-、SO_4~(2-)、F~-和H_2PO_4~-这5种阴离子的校正峰面积与质量浓度分别在0.5～100.0、0.2～20.0、0.5～100.0、0.2～4.0和0.2～5.0 mg/L范围内呈线性相关,相关系数分别为0.998 8、0.999 9、0.999 7、0.999 7、0.999 8。检出限均为0.05 mg/L,定量限均为0.15 mg/L,方法精密度均小于5%(n=6)。低、中和高质量浓度加标回收率在81.6%～108.6%之间,相对标准偏差在0.6%～3.7%之间(n=6)。用本法分析了7份饮用水样品,并与离子色谱法的结果相比较,除矿泉水中Cl~-结果偏低外,其余基本吻合。结论本方法简单,所用试剂环保,为饮用水中5种阴离子的常规检测提供了一种新方法,但不适合测定水样中低浓度的Cl~-。     

Electrochemistry of free chlorine and monochloramine and its relevance to the presence of Pb in drinking water

The commonly used disinfectants in drinking water are free chlorine (in the form of HOCl/OCl-) and monochloramine (NH2Cl). While free chlorine reacts with natural organic matter in water to produce chlorinated hydrocarbon byproducts, there is also concern that NH2Cl may react with Pbto produce soluble Pb(II) products--leading to elevated Pb levels in drinking water. In this study, electrochemical methods are used to compare the thermodynamics and kinetics of the reduction of these two disinfectants. The standard reduction potential for NH2Cl/Cl- was estimated to be +1.45 V in acidic media and +0.74 V in alkaline media versus NHE using thermodynamic cycles. The kinetics of electroreduction of the two disinfectants was studied using an Au rotating disk electrode. The exchange current densities estimated from Koutecky-Levich plots were 8.2 x 10(-5) and 4.1 x 10(-5) A/cm2, and by low overpotential experiments were 7.5 +/- 0.3 x 10(-5) and 3.7 +/- 0.4 x 10(-5) A/cm2 for free chlorine and NH2Cl, respectively. The rate constantforthe electrochemical reduction of free chlorine at equilibrium is approximately twice as large as that for the reduction of NH2Cl. Equilibrium potential measurements show that free chlorine will oxidize Pb to PbO2 above pH 1.7, whereas NH2Cl will oxidize Pb to PbO2 only above about pH 9.5, if the total dissolved inorganic carbon (DIC) is 18 ppm. Hence, NH2Cl is not capable of producing a passivating PbO2 layer on Pb, and could lead to elevated levels of dissolved Pb in drinking water.     

Biological mechanism for the toxicity of haloacetic acid drinking water disinfection byproducts

The halogenated acetic acids are a major class of drinking water disinfection byproducts (DBPs) with five haloacetic acids regulated by the U.S. EPA. These agents are cytotoxic, genotoxic, mutagenic, and teratogenic. The decreasing toxicity rank order of the monohalogenated acetic acids (monoHAAs) is iodo- > bromo- > chloroacetic acid. We present data that the monoHAAs inhibit glyceraldehyde-3-phosphate dehydrogenase (GAPDH) activity in a concentration-dependent manner with the same rank order as above. The rate of inhibition of GAPDH and the toxic potency of the monoHAAs are highly correlated with their alkylating potential and the propensity of the halogen leaving group. This strong association between GAPDH inhibition and the monoHAA toxic potency supports a comprehensive mechanism for the adverse biological effects by this widely occurring class of regulated DBPs.     

Rapid detection and toxicity assessment of ochratoxin A by Photobacterium leiognathi in drinking water

This study was aimed to develop a rapid technique for detection of ochratoxin A (OTA) by Photobacterium leiognathi (P. leiognathi) based on its inhibition of luminescence on P. leiognathi. The freeze-dried powder of P. leiognathi was incubated and grown aerobically in sterile liquid medium at 28 °C for 20 h. Optical cell density (OD) at wavelength of 610 nm was measured using UV spectrometer every 2 h. Different concentrations of standard OTA solution were used to measure its luminescence inhibition and calculate its half maximal inhibitory concentration (IC₅₀). Scanning electron microscopy (SEM), flow cytometry (FCM), sodium dodecyl sulphonate polyacrylamide gel electrophoresis (SDS-PAGE), DNA extraction and gel electrophoresis were used to observe the performance of P. leiognathi under the treatment of OTA. A correlation (R² > 0.98) was obtained between the relative luminosity unit of P. leiognathi and OTA concentration in the range of 0.01–20 mg L⁻¹ with recoveries of 80.8–87.4%. The effects of OTA on P. leiognathi are time-dependent, and the IC₅₀ value of 12.71 mg L⁻¹ at 30 min demonstrated its good sensitivity to OTA. The cells of P. leiognathi under 40 mg L⁻¹ OTA exposure for 30 mins showed morphological alterations, protein damage, apoptosis and necrosis. The aforementioned results indicate that biological assay is a promising and alternative method used for rapidly monitoring the sudden pollution of OTA in the early emergency warning of drinking water system.     

Comparative Mammalian cell cytotoxicity of water concentrates from disinfected recreational pools

Disinfection of recreational pools is essential to prevent outbreaks of infectious disease. Despite the health benefits of swimming, recent research demonstrated an association between the application of disinfectants to recreational pools and adverse health outcomes. Pool waters are extreme cases of disinfection that differ in important respects from disinfected drinking waters. Pool waters are continuously exposed to disinfectants over average residence times extending to months. Disinfection byproduct (DBP) precursors in pools include natural humic substances deriving from the tap water source plus inputs from bathers through urine, sweat, hair, skin, and consumer products including sunscreens and cosmetics. This study presents a systematic, chronic in vitro mammalian cell cytotoxicity analysis of different recreational waters with varied environmental conditions that were derived from a common tap water source. Recreational waters were significantly more toxic than their tap water source. Because trihalomethane concentrations are similar between tap waters and pool waters, using trihalomethanes to monitor exposure in epidemiological studies may not be the best metric. Of primary importance for cytotoxicity were illumination conditions. Pools subjected to a combination of ultraviolet light and free chlorine disinfection indoors, or outdoor sunlight exposure exhibited lower cytotoxicity than their indoor counterparts disinfected with free chlorine. Temperature and total organic carbon content, as an indirect measure of DBP precursors, were less important. Previous research on the same samples demonstrated the genotoxicity of an indoor pool disinfected with bromochlorodimethylhydantoin; the cytotoxicity of this sample was confirmed in the present study. While the association of reduced toxicity with illumination indicates that the agents responsible are photolabile, their identity is unclear. As a broad measure of adverse biological responses, cytotoxicity may be a useful metric to gauge the health impacts of alterations in pool operating conditions.     

毛霉紫外线诱变育种

从腐乳和千张（豆类发酵食品—宜宾名特产）中分离得到的毛霉菌株，经紫外线谤变处理及控温培养、筛选各得到一株生产能力较出发株高的突变株mr6（1，2）。该菌株在温度28℃条件时生长旺盛，产酶能力高，具有较好的遗传稳定性。     

“饮”领健康新生活,“喝”护人类绿色家园

水是生命之源,人类的生存与发展离不开水。随着人口的快速增长,以及人类文明的进步,家庭用水及工业用水量急速增加,从泉水、井水、河流及湖泊获得的清洁水源已无法满足生产生活的需要,新的供水系统得到开发,市政供水和包装饮用水成为人们主要的饮用水来源。但是,由于某些化学处理、可能的二次污染、管道恶化等原因,市政供水的水质和口感可能会发生些许改变。在安全性因素的考虑下,以及聚对苯二甲酸乙二醇酯(PET)瓶的出现,人们开始追求饮用水的口感和便利性……     

紫外线技术在纺织印染行业中的应用

简要介绍了紫外线技术在纺织印染行业中的应用,如处理纺纱用胶辊、利用其荧光效应鉴别纤维织物或服装的纤维种类、纤维表面改性以及固化处理等方面.指出紫外线技术是一种环保、高效、简便、快速的处理技术.用紫外线技术处理纺织品不用水作介质,也无需化学品、蒸汽,省去了烘干过程和废水处理,可操作性强,设备投资费用低.由于新型紫外光源的出现,紫外线技术得到了迅速发展.在Et益注重节能、环保的今天,紫外线技术的研究和应用前景将更加广阔.     

Livestock drinking water microbiology and the factors influencing the quality of drinking water offered to cattle

The microbial quality of livestock drinking water was evaluated in 473 cattle water troughs located at 99 different cattle operations. The mean log10-transformed coliform and Escherichia coli concentrations per milliliter of trough water were 1.76 +/- 1.25 (SD) and 0.98 +/- 1.06 (SD), respectively. The degree of E. coli contamination was positively associated with the proximity of the water trough to the feedbunk, protection of the trough from direct sunlight, lower concentrations of protozoa in the water, and warmer weather. Salmonella sp. were isolated from 2/235 (0.8%) troughs and shigatoxigenic-E. coli O157 was recovered from 6/473 (1.3%) troughs. Four experimental microcosms simulating cattle water troughs were used to further evaluate the effects of protozoal populations on the survival of E. coli O157 in cattle water troughs. Escherichia coli O157 of bovine fecal origin proliferated in all microcosms. Reduction of protozoal populations by treatment with cycloheximide was associated with increased persistence of E. coli O157 concentrations in the microcosms. Water troughs are a major source of exposure of cattle to enteric bacteria, including a number of foodborne pathogens, and this degree of bacterial contamination appeared to be associated with potentially controllable factors.     

二氧化氯氧化水中质子态联苯胺的反应机制

联苯胺类化合物是一类具有致基因突变、致癌性且在环境中广泛存在的有毒有害物质。以联苯胺作为代表性有机污染物,采用UV-vis、IR及GC/MS等方法研究了ClO2氧化水中质子态联苯胺的反应机理。指出了溶液pH值与联苯胺存在型体的关系,当pH值低于3.57时,溶液中联苯胺是以双质子态为主要存在形式的;控制溶液pH值2.0,对ClO2氧化水中质子态联苯胺的反应中间产物进行了鉴定。结果表明,该氧化反应中间产物依次为联苯醌二亚胺、联苯醌二肟和联苯醌,联苯醌最终被氧化成不饱和酸;通过分析ClO2与有机物反应特点和联苯胺分子结构的特性,在单电子转移理论的基础上,探讨了ClO2氧化质子态联苯胺可能的反应历程。