微生物污染源解析技术研究进展

针对目前新兴的微生物污染源解析技术（MST）研究进展进行了归纳总结.结果表明,标记物的源强特征显著影响水体微生物污染水平的评估,选用标记物时应同时考虑灵敏度和源强特征;与非目标物种样品产生交叉反应导致标记物特异性降低,可通过稀释样品或DNA纯化等手段降低假阳性信号强度;粪便源解析文库（FTL）中应涵盖的宿主种类,以及每类宿主应纳入的个体数量均会影响建库源解析结果的准确性,可通过权重分析来确定源文库中各宿主应囊括的样本量,提高识别污染源的准确性;FTL中的物种与土著微生物分类较为接近时,SourceTracker难以准确区分微生物污染来源,将土著微生物信息纳入FTL并多次运行程序可提高SourceTracker识别污染源的能力.未来应加强对标记物灵敏度和源强特征之间相关关系的研究,同时探讨标记物源强特征产生差异的成因以及交叉反应产生的机理;另一方面,应深入探究粪源微生物种内变异程度和土著微生物的种类对建库源解析法的影响机制,以期建立准确、完善的微生物污染源解析技术.     

再生水紫外线-氯联合消毒工艺特性研究

以二级出水作为消毒对象,比较了紫外线-氯联合消毒与单一紫外线消毒对水中肠道指示菌的灭活效果,考察了联合消毒工艺副产物(三卤甲烷)生成情况.结果表明,单一紫外线消毒对肠道指示菌的灭活曲线在剂量大于10mJ/cm2时存在拖尾现象,剂量为80mJ/cm2时对总大肠菌群最高对数灭活率约为2.5;而在紫外线剂量20mJ/cm2、氯投加量8mg/L(接触时间30min)条件下,紫外线-氯联合消毒对总大肠菌群的对数灭活率达到7.0.20mJ/cm2紫外线与8mg/L氯消毒组合及80mJ/cm2紫外线与3mg/L氯消毒组合均可有效灭活总大肠菌群浓度至3CFU/L以下.经紫外线照射后再氯消毒,二级出水中三卤甲烷生成量仅为10~55mg/L.80mJ/cm2紫外线照射再氯消毒后三卤甲烷生成量略高于20mJ/cm2紫外线照射再氯消毒的情形.紫外线消毒后投加氯消毒,可有效提高再生水消毒效果,控制消毒副产物生成量.     

Microbiological Monitoring of Marine Recreational Waters in Southern California

An inventory was conducted to assess the number, type, spatial distribution, and costs of microbiological monitoring programs in southern California marine waters from Point Conception to the US/Mexico International Border. The location of each sampling site was determined using global positioning system (GPS), and estimates of geographic coverage were determined using geographic information system (GIS) techniques. Twenty-one programs conducted 87,007 tests annually at 576 sites in the study area. The largest number of sites was sampled in Orange County, whereas the largest number of analyses was performed in Los Angeles County because monitoring programs in this area focused on daily monitoring. Fifteen of the 21 programs were managed by National Pollutant Discharge Elimination System (NPDES) permitted sewage effluent dischargers who sampled both offshore and shoreline waters and typically tested for three indicator bacteria (total coliform, fecal coliform, and enterococcus). Their combined efforts comprised 82% of all of the microbiological indicator analyses conducted on an annual basis. Five of the remaining monitoring organizations were public health agencies, which typically focus their efforts on testing only total coliforms. Laboratory methodology also varied considerably, with NPDES permittees predominantly utilizing membrane filtration while public health agencies generally used multiple tube fermentation or premanufactured test kits. Nearly three quarters of all the effort expended in southern California occurred along the shoreline as opposed to offshore locations. Two thirds of this shoreline effort was focused on high-use sandy beaches and in proximity to perennial freshwater outlets (storm drains and creeks). Most sampling occurred at a set of fixed sites that were revisited frequently, but only represented about 7% of the total shoreline. We estimated that roughly $3 million is spent annually on monitoring bathing water quality in southern California, exceeding that spent in any other part of the country.     

河水紫外线消毒的研究

本文对河水紫外线消毒进行了研究，得到了水的浊度，水层厚度以及辐射时间与总大肠菌群存活率之间的相关关系，试验结果表明，当浊度≤１２度，水层厚度≤７２ｍｍ辐射时间为５分钟时，消毒后出水中的总大肠菌群数≤３个／Ｌ，并且电耗为０．２９ｋｗ／ｍ＾３，该试验结果可作为工程设计的依据。     

DISINFECTION WITH QUATERNARY AMMONIUM COMPOUNDS1

ABSTRACT: The most common disinfection method is chlorination, however, it has been known that the practice of chlorination for water treatment in the Mississippi River area has caused a significant increase in mortality. The objective of this research was to search for effective disinfectants to replace chlorine. Three cationic surfactants have been tested for their bactericidal properties under various conditions. It has been found that 1 mg of cetyldimethyl-benzylammonium chloride can destroy about 4500 coliforms in one liter water within 10 minutes, under neutral pH conditions and room temperature. Cationic quaternary ammonium compound, therefore, can be a potential candidate disinfectant for replacing chlorine when necessary.     

STORM AND SEASONAL DISTRIBUTIONS OF FECAL COLIFORMS AND CRYPTOSPORIDIUM IN A SPRING1

ABSTRACT: The transmission of disease in ground water is a topic of great concern to government agencies, ground water specialists, and the general public. The purpose of this study was to compare the temporal variability in storm flow of fecal coliform bacteria densities and Cryptosporidium parvum oocyst densities in agriculturally impacted karst ground water. Cryptosporidium parvum oocyst densities ranged from 0 to 1,050 oocysts/1, and mean storm densities ranged from 3.5 to 156.8 oocysts/1. Fecal coliform densities ranged from less than 1 CFU/100ml to more than 40,000 CFU/100ml, and geometric mean storm densities ranged from 1.7 CFU/100ml to more than 7,000 CFU/100ml. Fecal coliform densities correlated well with flow during storms, but Cryptosporidium oocyst densities exhibited a great deal of sample to sample variability and were not correlated with flow. Fecal coliform densities did not correlate positively with Cryptosporidium oocyst densities. Fecal coliform densities were greatest at storm peaks, when sediment loads were also greatest. Multiple transport mechanisms for fecal coliform bacteria and C. parvum oocysts may necessitate various agricultural land management and livestock health maintenance practices to control movement of pathogens to karst ground water.     

FECAL COLIFORM RELEASE FROM CATTLE FECAL DEPOSITS1

ABSTRACT: Cowpies molded to a standard configuration and size were subjected to simulated rainfall, and the fecal coliform counts were determined using the most probable number (MPN) method of enumeration. The standard cowpie deposits were exposed to simulated rainfall once at ages 2 through 100 days. The effects of rainfall intensity and recurrent rainfall were also tested. Naturally-occurring fecal deposits were also tested to compare their results with those from the standard cowpies. A log-log regression was found to describe the decline in peak fecal coliform release with fecal deposit age. The 100-day-old fecal deposits produced peak counts of 4,200 fecal coliform per 100 milliliters of water. This quantity of release is minimal compared to the release from fresher fecal material. Rainfall intensity had little effect on peak fecal coliform release from fecal deposits that were 2 or 10 days old. At age 20 days the effect of rainfall intensity was significant; the highest intensity gave the lowest peak counts, and the lowest intensity gave the highest peak counts. The effect of rainfall intensity appears to be related to the dryness of the fecal deposits. Peak fecal coliform counts were significantly lowered when the fecal deposits were rained on more than once. This decline was thought to be produced by the loss of bacteria from the fecal deposits during the previous wettings. Standard cowpies produced a peak release regression that was not significantly different from the regression for the natural fecal deposits. Apparently, grossly manipulating the fecal deposits did not significantly change the release patterns.     

A DYNAMIC BACTERIAL MODEL FOR A RECREATIONAL LAKE1

ABSTRACT A dynamic mathematical model was constructed to examine bacterial contamination problems affecting Ford Lake, a small recreational lake in Southeast Michigan. The model was calibrated and verified using summer dry weather averaged data and data from three wet weather surveys. Model simulations demonstrated that the major bacterial contamination was attributable to storm related perturbations affecting two point sources: the Huron River and the Ypsilanti Sewage Treatment Plant. The nonpoint source contribution was relatively minor. The Model is currently being used by the State of Michigan Department of Natural Resources as a management tool for assessing the effectiveness of planned pollution abatement strategies     

STATEWIDE EMPIRICAL MODELING OF BACTERIAL CONTAMINATION OF SURFACE WATERS1

ABSTRACT: Bacterial contamination of surface waters is attributed to both urban and agricultural land use practices and is one of the most frequently cited reasons for failure to meet standards established under the Clean Water Act (CWA) (P.L. 92–500). Statewide modeling can be used to determine if bacterial contamination occurs predominantly in urban or agricultural settings. Such information is useful for directing future monitoring and allocating resources for protection and restoration activities. Logistic regression was used to model the likelihood of bacterial contamination using watershed factors for the state of Maryland. Watershed factors included land cover, soils, topography, hydrography, locations of septic systems, and animal feeding operations. Results indicated that bacterial contamination occurred predominantly in urban settings. Likelihood of bacterial contamination was highest for small watersheds with well drained and erodible soils and a high proportion of urban land adjacent to streams. The number of septic systems and animal feeding operations and the amount of agricultural land were not significant explanatory factors. The urban infrastructure tends to “connect” more of the watershed to the stream network through the creation of roads, storm sewers, and wastewater treatment plants. This may partly explain the relationship between urbanization and bacterial contamination found in this study.     

关于饮水机水细菌污染及使用若干问题探讨

为了解冷热两用饮水机所供水的细菌污染情况，对新出厂的饮用纯净水、饮水机中冷水、未沸水和沸水、桶中水等不同水样中细菌总数和大肠菌群分别进行了检测分析。结果表明，未沸水灭菌情况不稳定，沸水灭菌效果很好；随时间推移，纯净水中的细菌总数呈递增趋势，并且增长速度较快，其污染源主要来自空气和饮水机本身，特别是饮水机内胆的污染不容忽视。所有水样中均未检出大肠菌群。