饮用水中藻毒素检测技术研究进展

随着水体富营养化问题日益严重，藻毒素问题成为最近研究的热点，因此迫切需要一种先进、可靠和高效的藻毒素检测技术。本文综述了目前饮用水中关于微囊藻毒素的检测技术，包括动物试验法、细胞毒性检测技术、高效液相色谱技术、毛细管电泳、MMPB法、酶联免疫吸附测定、免疫层析法及蛋白磷酸酶抑制分析法等，并对未来藻毒素检测技术的发展提出了展望。     

水中铅的测定方法比较

由于水中铅的含量较低,常用的测定方法是石墨炉原子吸收法和氢化物发生-原子荧光法。通过对干扰的消除方法、检出限实验、加标回收实验以及检测消耗时间和涉及药品试剂等方面的比较,得出石墨炉原子吸收法和氢化物发生-原子荧光法检测水中铅的优劣:石墨炉原子吸收法前处理较为简单,所涉及药品较少,成本较低,适合大批量样品检测;氢化物发生-原子荧光法的精密度高于石墨炉原子吸收法,适合于科研型实验研究。     

食源性致病微生物快速检测技术研究进展

对国内外食源性致病菌的快速检测技术研究进展进行了简要综述,包括改进微生物培养法、酶联免疫（ELISA）法、PCR技术、基因芯片技术、直接计数法、自动化仪器分析技术等。     

气提/FID法检测石化企业冷却水中VOCs

冷却水塔VOCs逸散管控在石化行业VOCs深度减排工作中占有重要地位,水中VOCs定量检测尤显重要。文章以某地区3家石化企业为研究对象,采用气提／ＦＩＤ 法对4座冷却水塔进行VOCs定量检测研究,将检测结果与传统GC/MS法进行对比,以期指导水中VOCs定量检测工作。研究结果表明,石化企业冷却水中VOCs浓度为11.9～22.8μg/L（以甲烷计）,主要含有丙酮、氯仿、异丙醇及苯乙烯等组分;气提/FID法更有利于低沸点VOCs组分的检测,对于水中溶解度较高和吹除效率不佳的醇类、酸类等VOCs化合物检测结果可能偏低。     

生物技术在环境监测中的应用

文章介绍了实验室常用的生物监测方法,从生物学角度来判断环境污染的程度,为环境质量的监测和评价提供依据。着重对细菌学监测、隐孢子虫和贾第鞭毛虫的监测、浮游动植物监测、生物综合毒性监测等进行了专门论述。     

纳米TiO2光催化降解技术在污水处理中的应用

光催化技术是一种新兴的高效节能现代污水处理技术，目前大部分还处于实验研究阶段。本文介绍了TiO2光催化降解水中有机物的机理以及pH值、载体、外加氧化剂等对其光催化活性的影响，TiO2光催化剂的表面修饰及与其它技术的联用情况。讨论了光电催化、太阳能利用等对光催化领域的推动作用，并指出在该领域的研究中存在问题和发展方向。     

水中粪大肠菌群检测方法及其研究进展

水体受粪便污染后可导致肠道病毒的扩散和传播，粪大肠菌群恰可准确地反映水体受粪便污染的状况，因此，对粪大肠菌群的检测是否精确、快速对疾病的预防有至关重要的作用。本文对目前粪大肠菌群的分析方法及其研究改进进行了综述和比较，认为目前水中粪大肠菌群的检测可优先选择纸片法和酶底物法，而经过改进的多管发酵法（EC培养法，乳糖蛋白胨培养法），若再加以验证完善，亦可成为一个好的选择。     

臭氧氧化水中有机污染物作用规律及动力学研究方法

本文对臭氧氧化水中有机污染物的作用规律及氧化动力学研究方法进行了综述。臭氧是一种强氧化剂，它能通过臭氧直接反应或产生羟基自由基进行间接反应以及两者的结合对有机和无机化合物进行氧化。臭氧有选择性地氧化有机污染物，主要与双键、活性芳香系统和未被质子化的胺类发生反应，而羟基自由基则可以和水中绝大多数化合物无选择性地快速反应，臭氧动力学的研究也涉及到臭氧和羟基自由基的问题，其反应速率常数的测定多采用溶质消耗法和竞争动力学法。     

油田采出水膜法处理技术应用研究进展

对采出水膜法处理技术中的微滤、超滤、纳滤、反渗透膜以及集成技术的应用进行研究,分析成本,总结各技术的特点。超滤、微滤主要处理的是水中的油类以及悬浮物和细菌,纳滤对二价离子的脱除率较高,反渗透技术可以有效降低采出水矿化度。在实际采出水处理中,可综合运用膜技术和生物法达到更好的处理效果。     

磁加载混凝技术在水处理中的应用

磁加载混凝技术具有泥水分离速度快、污水处理周期短、占地面积小和污水处理成本低的优点。具体阐述了磁加载混凝法中磁种的选择以及新型混凝剂的研究进展;介绍了磁加载混凝技术在水处理中的应用。研究表明,磁加载混凝法对水中重金属离子和磷有较好的去除效果,一般可达90%以上,对化学需氧量(COD)、氨氮、浊度的去除效果也很明显。     

Environmental load of Cryptosporidium parvum oocysts from cattle manure in feedlots from the central and western United States

The first step in assessing the risk of water contamination by Cryptosporidium parvum oocysts from feedlot cattle (Bos taurus) production systems is to quantify the number of C. parvum oocysts present in the fecal material deposited by feedlot cattle. Our primary objective for this project was to estimate the daily environmental load of C. parvum oocysts in fecal material deposited by feedlot cattle from across the central and western USA. Our secondary goal was to genotype isolates of C. parvum from feedlot cattle to help facilitate proper identification of mammalian sources of waterborne C. parvum. Based on 5274 fecal samples from 22 feedlots in seven states (California, Washington, Colorado, Oklahoma, Texas, Nebraska, and South Dakota), we estimated a point prevalence of C. parvum of 0.99 to 1.08% in fecal material from feedlot pens from a wide range of climates and a diverse range of feedlot management systems. On average, fresh fecal material from throughout feedlot systems (recent arrivals to nearing slaughter) contained about 1.3 to 3.6 oocysts/g feces, which roughly translates to about 2.8 x 10(4) to 1.4 x 10(5) oocysts/animal per day.     

Evaluation of PCR-based quantification techniques to estimate the abundance of atrazine chlorohydrolase gene atzA in rhizosphere soils

There are many challenges in the accurate quantification of bacterial genes, such as the atrazine-degrading enzyme antA from Pseudomonas sp. strain ADP, from soil samples. We compared four quantitative methods for enumeration of atrazine-degrading bacteria in rhizosphere environments and utilized the optimal probe-based real-time polymerase chain reaction (PCR)-based method in an ongoing bioremediation experiment to monitor atzA copy number over time. We compared three quantitative PCR (qPCR) based methods--quantitative competitive PCR and two real-time qPCR methods--to traditional dilution-plate counting techniques. The optimal real-time qPCR assay was then used to monitor atzA copy number over time in the robust atrazine-degrading Pseudomonas sp. strain ADP-spiked rhizosphere environment. The use of sensitive and reliable probe-based real-time qPCRs for the enumeration of bacterial catabolic genes allows for their detection from soil samples and monitoring of potential degradative populations over time. The addition of arrazine-biodegrading bacteria into arrazine-contaminated sites to remove entrapped atrazine is a promising approach for mitigating atrazine pollution and its metabolites. The methodology contained herein will allow for optimal monitoring of atzA in rhizosphere soil with or without the addition of biodegradative Pseudomonas sp. strain ADP of bacteria.     

Survival of Cryptosporidium parvum oocysts in calf housing facilities in the New York City watersheds

Pathogen contamination of the public drinking water supply in the New York City watersheds is a serious concern. New York City's Watershed Agriculture Program is working with dairy farms in the watersheds to implement management practices that will reduce the risk of pathogens contaminating the water supply. Solar calf housing (SCH) was suggested as a best management practice (BMP) to control Cryptosporidium parvum, a common protozoan parasite that causes disease in humans. This BMP targets young calves because they are the primary source of C. parvum in dairy herds. The objective of this project was to assess and compare the survivability of C. parvum in SCH and in conventional calf housing (CCH), usually located in the main barn. C. parvum oocysts were secured in sentinel chambers and placed in SCH and CCH bedding on four farms. The chambers were in thermal, chemical, and moisture equilibrium with their microenvironments. An oocyst-filled control chamber, sealed from its surroundings, was placed near each chamber. Chambers and controls were sampled after 4, 6, and 8 wk. Oocyst viability in the chambers decreased to less than 10% in warm months and between 15 and 30% in the winter months. The viability of the control oocysts was similar to the chambers during warm months and generally higher during winter months. There was no significant (P > 0.05) difference in the viability decrease between SCH and CCH. Although oocyst viability was similar in both types of calf housing, SCH allow contaminated calf manure to be isolated from the main barn manure and potentially managed differently and in a way to decrease the number of viable oocysts entering the environment during field spreading.     

Farm factors associated with reducing Cryptosporidium loading in storm runoff from dairies

A systems approach was used to evaluate environmental loading of Cryptosporidium oocysts on five coastal dairies in California. One aspect of the study was to determine Cryptosporidium oocyst concentrations and loads for 350 storm runoff samples from dairy high use areas collected over two storm seasons. Selected farm factors and beneficial management practices (BMPs) associated with reducing the Cryptosporidium load in storm runoff were assessed. Using immunomagnetic separation (IMS) with direct fluorescent antibody (DFA) analysis, Cryptosporidium oocysts were detected on four of the five farms and in 21% of storm runoff samples overall. Oocysts were detected in 59% of runoff samples collected near cattle less than 2 mo old, while 10% of runoff samples collected near cattle over 6 mo old were positive. Factors associated with environmental loading of Cryptosporidium oocysts included cattle age class, 24 h precipitation, and cumulative seasonal precipitation, but not percent slope, lot acreage, cattle stocking number, or cattle density. Vegetated buffer strips and straw mulch application significantly reduced the protozoal concentrations and loads in storm runoff, while cattle exclusion and removal of manure did not. The study findings suggest that BMPs such as vegetated buffer strips and straw mulch application, especially when placed near calf areas, will reduce environmental loading of fecal protozoa and improve stormwater quality. These findings are assisting working dairies in their efforts to improve farm and ecosystem health along the California coast.     

Overland and near-surface transport of Cryptosporidium parvum from vegetated and nonvegetated surfaces

Understanding microbial pathogen transport patterns in overland flow is important for developing best management practices for limiting microbial transport to water resources. Knowledge about the effectiveness of vegetative filter strips (VFS) to reduce pathogen transport from livestock confinement areas is limited. In this study, overland and near-surface transport of Cryptosporidium parvum has been investigated. Effects of land slopes, vegetation, and rainfall intensities on oocyst transport were examined using a tilting soil chamber with two compartments, one with bare ground and the other with brome (Bromus inermis Leyss.) vegetation. Three slope conditions (1.5, 3.0, and 4.5%) were used in conjunction with two rainfall intensities (25.4 and 63.5 mm/h) for 44 min using a rainfall simulator. The vegetative surface was very effective in reducing C. parvum in surface runoff. For the 25.4 mm/h rainfall, the total percent recovery of oocysts in overland flow from the VFS varied from 0.6 to 1.7%, while those from the bare ground condition varied from 4.4 to 14.5%. For the 63.5 mm/h rainfall, the recovery percentages of oocysts varied from 0.8 to 27.2% from the VFS, and 5.3 to 59% from bare-ground conditions. For all slopes and rainfall intensities, the total (combining both surface and near-surface) recovery of C. parvum oocysts was considerably less from the vegetated surface than those from the bare-ground conditions. These results indicate that the VFS can be a best management practice for controlling C. parvum in runoff from animal production facilities.     

Efficacy of vegetated buffer strips for retaining Cryptosporidium parvum

Overland and shallow subsurface hydrologic transport of pathogenic Cryptosporidium parvum oocysts from cattle feces into surface drinking water supplies is a major concern on annual grasslands in California's central and southern Sierra Nevada foothills. Soil boxes (0.5 m wide x 1.1 m long x 0.3 m deep) were used to evaluate the ability of grass vegetated buffer strips to retain 2 x 10(8) spiked C. parvum oocysts in 200-g fecal deposits during simulated rainfall intensities of 30 to 47.5 mm/h over 2 h. Buffers were comprised of Ahwahnee sandy loam (coarse-loamy, mixed, active, thermic Mollic Haploxeralfs; 78:18:4 sand to silt to clay ratio; dry bulk density = 1.4 g/cm(3)) set at 5 to 20% land slope, and >/=95% grass cover (grass stubble height = 10 cm; biomass = 900 kg/ha dry weight). Total number of oocysts discharged from each soil box (combined overland and subsurface flow) during the 120-min simulation ranged from 1.5 x 10(6) to 23.9 x 10(6) oocysts. Observed overall mean log(10) reduction of total C. parvum flux per meter of vegetated buffer was 1.44, 1.19, and 1.18 for buffers at 5, 12, and 20% land slope, respectively. Rainfall application rate (mm/h) was strongly associated with oocyst flux from these vegetated buffers, resulting in a decrease of 2 to 4% in the log(10) reduction per meter buffer for every additional mm/h applied to the soil box. These results support the use of strategically placed vegetated buffers as one of several management strategies that can reduce the risk of waterborne C. parvum attributable to extensive cattle grazing on annual grassland watersheds.     

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.