首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 65 毫秒
1.
A tool, based on a multidisciplinary field investigation approach for studying the characteristics of a hypersaline spring, was developed and its effectiveness tested on a spring in southern Italy; a preliminary model of the aquifer system at medium and local scale was derived. Hydrologic measurements, vertical electric soundings, and chemical and isotopic (δ18O, δ2H, 3H) analyses were undertaken, along with microbiological analyses and species identification. These demonstrate the coexistence of hypersaline and fresh water, generating a significant diversification of the groundwater hydrochemical signature. The isotopic signature shows that both types of water have a meteoric origin. Microbial contamination of fecal origin indicates the mixing of hyper- and low- saline water related to local infiltration. The hypersaline groundwater flows in confined horizons within a sequence that is mainly of fractured clays. These horizons are probably concentrated where well-developed fracture network and dissolution openings within evaporitic rocks enhance fluid flow. In a wider context, this study determines that microbiological pollution of saline groundwater may not be detected if using nonhalophilic bacterial indicators such as fecal coliforms. Fecal enterococci are better indicators, due to their higher halotolerance.  相似文献   

2.
Limestone aquifers in Southern Italy are often affected by bacterial contamination produced by pasture and agriculture. The main goals of this study were (1) to analyze the role of land use and environmental factors on microbial contamination and, (2) to identify, at field scale, the most suitable indicator of fecal pollution, by comparing fecal coliforms and fecal enterococci. Analyzing surface and spring water, it was noted that both fecal indicators showed a significant decrease during the period characterized by freezing and/or freeze-thaw intervals. The data analysis shows that fecal coliforms are characterized by a significant decrease in population (3 orders of magnitude, at least) during the freezing period, while fecal enterococci are temporarily inhibited. A taxonomic classification of fecal enterococci detected in spring water samples was performed by the API 20 Strep system and by sequencing of the ribosomal 16S DNA genes. The results showed that freezing conditions did not cause any significant change on the set of enterococcal species.  相似文献   

3.
Karst aquifers are particularly vulnerable to bacterial contamination. Especially in developing countries, poor microbial water quality poses a threat to human health. In order to develop effective groundwater protection strategies, a profound understanding of the hydrogeological setting is crucial. The goal of this study was to elucidate the relationships between high spatio-temporal variability in microbial contamination and the hydrogeological conditions. Based on extensive field studies, including mapping, tracer tests and hydrochemical analyses, a conceptual hydrogeological model was developed for a remote and geologically complex karst area in Northern Vietnam called Dong Van. Four different physicochemical water types were identified; the most important ones correspond to the karstified Bac Son and the fractured Na Quan aquifer. Alongside comprehensive investigation of the local hydrogeology, water quality was evaluated by analysis for three types of fecal indicator bacteria (FIB): Escherichia coli, enterococci and thermotolerant coliforms. The major findings are: (1) Springs from the Bac Son formation displayed the highest microbial contamination, while (2) springs that are involved in a polje series with connections to sinking streams were distinctly more contaminated than springs with a catchment area characterized by a more diffuse infiltration. (3) FIB concentrations are dependent on the season, with higher values under wet season conditions. Furthermore, (4) the type of spring capture also affects the water quality. Nevertheless, all studied springs were faecally impacted, along with several shallow wells within the confined karst aquifer. Based on these findings, effective protection strategies can be developed to improve groundwater quality.  相似文献   

4.
Three bacterial water quality indicators,Clostridium perfringens, enterococci, and fecal coliforms, were compared to F-RNA coliphages for their survival during chlorination at several municipal wastewater treatment plants in Rhode Island and seasonally during transport in a section of the Narragansett Bay estuary. F-RNA coliphages were used as the best available indicator for the survival of Noroviruses (formerly Norwalk-like virus), the most frequently identified agent for the most prevalent waterborne disease (an acute but benign gastroenteritis), which has yet to be propagated in tissue culture and for which there is no lower animal model. Inactivation of the enterococci and fecal coliforms during wastewater chlorination was much greater than that of the F-RNA coliphages whose inactivation was essentially the same as that of C.perfringens. Survival of the F-RNA coliphages andC. perfringens during winter transport down Narragansett Bay were comparable to each other and greater than that for the enterococci or fecal coliforms. During the summer,C. perfringens survived longer than the other three indicators, possibly because the virus-like (F-RNA coliphages) and the two vegetative bacterial indicators were more susceptible than theC. perfringens spores to the lethal effects of sunlight and elevated water temperatures during the summer. Based on these findings, F-RNA coliphages seems to be a reliable indicator of viral contamination and die-off in estuarine waters.  相似文献   

5.
Located in the southeast of Tunisia, on the Mediterranean Sea, Jerba Island has a semiarid climate condition. The surface water scarcity has made groundwater the main source to supply the domestic, touristic, and agricultural water demand. Unconfined aquifer is a vulnerable costal aquifer system that undergoes several phenomena. This work aims at assessing the geochemical and bacteriological groundwater quality, defining groundwater pollution sources and promoting sustainable development and effective management of groundwater resources in Jerba Island. Data were collected after the wet season in 2014 from 79 wells. Electric conductivity, pH, TDS, and major and fecal tracers (total coliforms, thermotolerant coliforms, Escherichia coli, and Salmonella) were analyzed. Geochemical modeling including the relationships between geochemical tracers Na+ vs. Cl?, Ca2+ vs. Cl?, K+ vs. Cl?, representative ionic ratios (Br?/Cl?, Na+/Cl?, Mg2+/Ca2+), and statistical analysis were used to specify major process contributing to groundwater pollution and main factors controlling groundwater mineralization in the island. Groundwater varieties were hydrochemically classified into three types in terms of salinity values: group 1 (8.86%) to fresh water, group 2 (27.84%) to brackish water, and group 3 (63.29%) belongs to saline water. In addition, groundwater quality revealed high concentrations in chemical pollution tracers (Na+, Cl?, SO4 2?, and NO3 ?) and fecal tracers. Besides, most of the sampled wells were contaminated with nitrate (50.63%). Also, thermotolerant coliforms and E. coli were detected in all groundwater samples (96.2% of wells). Results indicated that the Jerba shallow aquifer was under serious threat from both natural and anthropogenic contamination. However, the wild discharge of domestic effluents, septic tanks, and sewage were the main origins of underground water contamination in Jerba Island. The reduction of fecal sources, through constructing normalized latrines is thus recommended.  相似文献   

6.
Because Taiwan is a subtropical island, many pleasure beaches are situated on its coast. However, according to long-term monitoring data, fecal contamination at Taiwanese coastal beaches frequently exceeds the U.S. Environmental Protection Agency (EPA) guidelines. To avoid public health hazards, mapping the spatial extent of this contamination is crucial. This study applied indicator kriging (IK) to probabilistically assess the water quality of bathing beaches on the Taiwanese coast. Moreover, because the discontinuity of the traditional Cartesian coordinate established on an island coastline is difficult for geostatistical estimates, this study proposed a novel kriging estimation approach to deal with this problem. First, a one-dimensional (1-D) cyclic coordinate system of the Taiwanese coast was established using primary and secondary coordinates at each beach site. Escherichia coli (E. coli) and enterococci concentrations at coastal beaches were converted into indicator variables according to the U.S. EPA guidelines. IK was then used to spatially model the occurrence probabilities that exceeded the U.S. EPA guidelines for E. coli and enterococci. Finally, the water quality of bathing beaches on the Taiwanese coast was classified on the basis of the estimated probabilities. The study results indicated that bathing on the central western, northeastern, and southeastern Taiwanese coasts poses a potential threat to human health caused by high levels of fecal contamination. Moreover, primary and secondary coordinates established at beach sites were capable of analyzing the spatial variability and kriging estimates of the 1-D cyclic coordinates along the coastline.  相似文献   

7.
Providing clean and good quality water is essential for sustaining human health and life, and for ensuring the preservation of ecosystems. The purpose of this paper is to identify the chemical and microbiological characteristics of drinking water source of Cankiri City (as raw and purified) and tap water samples of central Cankiri and its towns. The water quality in Cankiri Province was evaluated by comparing these parameters with permissible limits set by Turkish legislation and World Health Organization (WHO). Raw and purified water samples were analyzed for chemical and microbiological qualities, trace metal, pesticide, polycyclic aromatic hydrocarbon (PAH), trihalomethane (THM), and benzene contents. These analyses indicated that the parameters exceeded those of the Turkish legislation (phenolic substance, biochemical O2 demand, Mn, Se, fecal coliform) and the WHO guidelines (pH, phenolic substance, Cd, Se, fecal coliform). In this study, tap water samples were also collected from 50 sampling sites from central Cankiri and its towns during 2010. In these samples, chemical characteristics (bromide, free chlorine, nitrate and nitrite), carbamate, herbicide and fungicide contents, and microbiological contaminants were investigated. In the tap water samples, it was found that free chlorine concentrations exceeded the Turkish guidelines. Escherichia coli, total coliform and enterococci were used as indicators of possible sewage contamination due to inappropriate water distribution. Our results also indicated that significant microbiological contaminations in the tap water samples were above the guidelines for drinking water given by the Turkish legislation and WHO, and might pose a health risk. This investigation of drinking water samples of the Cankiri Province would point to the need of a new drinking water treatment strategy to ensure the safety of consumers.  相似文献   

8.
泉州市地处福建省东南部,工农业均比较发达。随着经济的发展,工矿企业遗留下来的污染问题也愈发突出。选择重金属Pb和Cr为研究对象,通过土柱实验和Hydrus-1D软件模拟,研究其在红壤和风沙土中的迁移特征。结果表明:重金属Cr在土壤剖面中的迁移速率和迁移量变化明显,尤其是风沙土,重金属Cr可以在两个月左右迁移至土壤剖面底部(80cm土层厚度)进入地下含水层;而重金属Pb在土壤剖面中的迁移速率很慢,迁移量也不大,污染源产生的污染物绝大多数在研究期内均被表层土壤吸附。因此在场地污染调查、评价和修复时,重金属Pb主要应该针对污染场地表层土壤层,而重金属Cr主要应考虑地下水,尤其是风沙土区域的地下水,且应于污染初期进行污染控制。  相似文献   

9.
In a continuing effort to develop inexpensive source tracking methods to detect human fecal contamination in environmental waters, targeted sampling was combined with fluorometry. Targeted sampling works by identifying hot spots of fecal contamination through multiple samplings over ever-decreasing distances. Fluorometry identifies human fecal contamination by detecting optical brighteners, primarily from laundry detergents. Because organic matter fluoresces and interferes with fluorometry, two locations were chosen for sampling: waters relatively low in organic matter at Mayagüez Bay, Puerto Rico, and waters relatively high in organic matter at St. Simons Island, Georgia. In Puerto Rico, targeted sampling and fluorometry quickly and easily identified two hot spots of human fecal contamination in the Yagüez River, which flows through the city of Mayagüez. Another source tracking method, detection of theesp gene, confirmed their human origin. On St. Simous Island, targeted sampling and fiuorometry identified two hot spots of potential human fecal contamination. Detection of theesp gene confirmed the human origin of one site but not the other, most likely because background organic matter fluorescence interfered with fhiorometry. A separate experiment showed that adding a 436-um emission filter to the fluorometer reduced this background fluorescence by > 50%. With the 436-nm Filter in place, another sampling was conducted on St. Simons Island, and the second hot spot was identified as fecal contamination from birds. As long as the fluorometer was equipped with a 436-nm filter and organic matter concentrations were considered, targeted sampling combined with fluorometry was a relatively inexpensive method for identifying human fecal contamination in water.  相似文献   

10.
Groundwater is inherently susceptible to contamination from anthropogenic activities and remediation is very difficult and expensive. Prevention of contamination is hence critical in effective groundwater management. In this paper an attempt has been made to assess aquifer vulnerability at the Russeifa solid waste landfill. This disposal site is placed at the most important aquifer in Jordan, which is known as Amman-Wadi Sir (B2/A7). The daily-generated leachate within the landfill is about 160 m3/day and there is no system for collecting and treating this leachate. Therefore, the leachate infiltrates to groundwater and degrades the quality of the groundwater. The area is strongly vulnerable to pollution due to the presence of intensive agricultural activity, the solid waste disposal site and industries. Increasing groundwater demand makes the protection of the aquifer from pollution crucial. Physical and hydrogeological characteristics make the aquifer susceptible to pollution. The vulnerability of groundwater to contamination in the study area was quantified using the DRASTIC model. The DRASTIC model uses the following seven parameters: depth to water, recharge, aquifer media, soil media, topography, impact on vadose zone and hydraulic conductivity. The water level data were measured in the observation wells within the disposal site. The recharge is derived based on precipitation, land use and soil characteristics. The aquifer media was obtained from a geological map of the area. The topography is obtained from the Natural Resources Authority of Jordan, 1:50,000 scale topographic map. The impact on the vadose zone is defined by the soil permeability and depth to water. The hydraulic conductivity was obtained from the field pumping tests. The calculated DRASTIC index number indicates a moderate pollution potential for the study area.  相似文献   

11.
The use of groundwater as a drinking water resource requires knowledge of its microbiological status and quality. In contrast to conventional microbiological monitoring of groundwater, the present study not only considers faecal indicator bacteria, but also covers a wide spectrum of microorganisms, including bacterial pathogens (verotoxin-producing E. coli, Campylobacter spp. and Salmonella spp., as well as Pseudomonas aeruginosa), human enteric viruses (norovirus, enterovirus, rotavirus and adenovirus) and parasitic protozoa (Cryptosporidium oocysts and Giardia cysts). Samples collected at karst sites of the Swiss National Groundwater Monitoring network revealed the presence of a large diversity of microorganisms of faecal origin, the occurrence of which could be linked to specific hydrogeological settings and situations. The findings represent a ‘snapshot’ of the microbiological status at the monitoring sites and provide a national overview of the types and presence of microorganisms in Swiss karst groundwater. In addition to microbiological parameters related to faecal contamination, the overall bacterial load in groundwater was assessed using cell density measurements (i.e. total cell count), which yielded typical ranges for this ecological parameter. The study highlights differential vulnerability of karst groundwater to microbiological contamination, as well as its relationship with the microbial biocenoses, i.e. the interplay of allochthonous and autochthonous microbial components. On the basis of this data set, a microbiological classification of karst aquifers is proposed and discussed with respect to spring dynamics and vulnerability.  相似文献   

12.
Samples of topsoil together with reference samples of subsurface soil from a depth of 80–90 cm were collected in the central-northern part of the Zambian Copperbelt to distinguish lithogenic sources of metals from anthropogenic contamination of soils caused by fallout of dust from mining operations, flotation ore treatment plants, tailings dams, smelters and slag dumping grounds. The total sulphur, Cu and Co contents were found to be significantly higher in topsoil relative to subsurface soil over a large part of the surveyed area, and Zn, Pb, As and Hg contents showed a definite increase in the close neighbourhood of smelters and in the direction of prevailing winds. This indicates that the increase of these elements in the topsoil is due to anthropogenic activities. The areal extent and degree of anthropogenic contamination of topsoil can be expressed by an enrichment index (EI) based on the average ratio of the actual and median concentrations of the given contaminants. Although the contamination of soil by dust fallout decreases progressively with depth in the soil profile, in areas strongly affected by mining and mineral processing the anthropogenic contamination by sulphur and copper can be traced to a depth of 80–90 cm. In contrast, the concentration of elements such as Cr, Ni, and V, that show a direct correlation with the content of iron in the soils, increases in the subsurface soil relative to the topsoil. This is particularly evident in areas underlain by rocks of the Katanga Supergroup.  相似文献   

13.
Multiple chemical constituents (nutrients; N, O, H, C stable isotopes; 64 organic wastewater compounds, 16 pharmaceutical compounds) and microbiological indicators were used to assess the impact on groundwater quality from the land application of approximately 9.5 million liters per day of treated municipal sewage effluent to a sprayfield in the 960-km2 Ichetucknee Springs basin, northern Florida. Enriched stable isotope signatures (δ18O and δ2H) were found in water from the effluent reservoir and a sprayfield monitoring well (MW-7) due to evaporation; however, groundwater samples downgradient from the sprayfield have δ18O and δ2H concentrations that represented recharge of meteoric water. Boron and chloride concentrations also were elevated in water from the sprayfield effluent reservoir and MW-7, but concentrations in groundwater decreased substantially with distance downgradient to background levels in the springs (about 12 km) and indicated at least a tenfold dilution factor. Nitrate-nitrogen isotope (δ15N–NO3) values above 10 ‰ in most water samples were indicative of organic nitrogen sources except Blue Hole Spring (δ15N–NO3 = 4.6–4.9 ‰), which indicated an inorganic source of nitrogen (fertilizers). The detection of low concentrations the insect repellent N,N-diethyl-metatoluamide (DEET), and other organic compounds associated with domestic wastewater in Devil’s Eye Spring indicated that leakage from a nearby septic tank drainfield likely has occurred. Elevated levels of fecal coliforms and enterococci were found in Blue Hole Spring during higher flow conditions, which likely resulted from hydraulic connections to upgradient sinkholes and are consistent with previoius dye-trace studies. Enteroviruses were not detected in the sprayfield effluent reservoir, but were found in low concentrations in water samples from a downgradient well and Blue Hole Spring during high-flow conditions indicating a human wastewater source. The Upper Floridan aquifer in the Ichetucknee Springs basin is highly vulnerable to contamination from multiple anthropogenic sources throughout the springs basin.  相似文献   

14.
Water quality monitoring in Hanalei Bay, Kaua`i (Hawai`i, USA) has documented intermittent high concentrations of nutrients (nitrate, phosphate, silica, and ammonium) and fecal indicator bacteria (FIB, i.e., enterococci and Escherichia coli) in nearshore waters and spurred concern that contaminated groundwater might be discharging into the bay. The present study sought to identify and track sources of nutrients and FIB to four beaches in Hanalei Bay and one beach outside the bay, together representing a wide range of land uses. 223Ra and 224Ra activity, salinity, nutrient and FIB concentrations were measured in samples from the coastal aquifer, the nearshore ocean, springs, the Hanalei River, and smaller streams. In addition, FIB concentrations in beach sands were measured at each site, and the enterococcal surface protein (esp) gene assay was used to investigate whether the observed FIB originated from a human source. Nutrient concentrations in groundwater were significantly higher than in nearshore water, inversely correlated to salinity, and highly site specific, indicating local controls on groundwater quality. Fluxes of groundwater into Hanalei Bay were calculated using a mass-balance approach and represented at least 2–10% of river discharges. However, submarine groundwater discharge (SGD) may provide 2.7 times as much nitrate + nitrite to Hanalei Bay as does the Hanalei River. It may also provide significant fluxes of phosphate and ammonium, comprising 15% and 20% of Hanalei River inputs, respectively. SGD-derived silica inputs to the bay comprised less than 3% of Hanalei River inputs. FIB concentrations in groundwater were typically lower than those in nearshore water, suggesting that significant FIB inputs from SGD are unlikely. Positive esp gene assays suggested that some enterococci in environmental samples were of human fecal origin. Identifying how nutrients and FIB enter nearshore waters will help environmental managers address pressing water quality issues, including exceedances of the state Enterococcus water quality standard and nutrient loading to coral reefs.  相似文献   

15.
Different geoenvironmental site investigation techniques to assess contamination from a municipal solid waste disposal site in Brazil are presented here. Superficial geophysical investigation (geoelectrical survey), resistivity piezocone penetration tests (RCPTU), soil samples collected with direct-push samplers and water samples collected from monitoring wells were applied in this study. The application of the geoelectrical method was indispensable to identify the presence and flow direction of contamination plumes (leachate) as well as to indicate the most suitable locations for RCPTU tests and soil and water sampling. Chemical analyses of groundwater samples contributed to a better understanding of the flow of the contaminated plume. The piezocone presented some limitations for tropical soils, since the groundwater level is sometimes deeper than the layer which is impenetrable to the cone, and the soil genesis and unsaturated conditions affect soil behavior. The combined interpretation of geoelectrical measurements and soil and water samplings underpinned the interpretation of RCPTU tests. The interpretation of all the test results indicates that the contamination plume has already overreached the landfill’s west-northwest borders. Geoenvironmental laboratory test results suggest that contamination from the solid waste disposal site has been developing gradually, indicating the need for continuous monitoring of the groundwater.  相似文献   

16.
The fate and transport of As was examined at an industrial site where soil- and groundwater contamination are derived from the application of As2O3 as a herbicide. Application of arsenical herbicides was discontinued in the 1970s and soils in the source area were partially excavated in 2003. Arsenic contamination (up to 280 mg/kg) remains in the source area soils and a plume of As-contaminated groundwater persists in the surficial aquifer downgradient of the source area with maximum observed As concentrations of 1200 μg/L near the source area. The spatial extent of As contamination as defined by the 10 μg/L contour appears to have remained relatively stable over the period 1996–2006; the boundary of the 1000 μg/L contour has retreated over the same time period indicating a decrease in total As mass in the surficial groundwater.In column experiments conducted with source area soil, the As concentrations in the column effluent were comparable to those observed in groundwater near the source area. A substantial fraction of the As could be leached from the source area soil with ammonium sulfate and ammonium phosphate. Exhaustive extraction with background groundwater removed most of the total As. These results indicate that As in the source area soils is geochemically labile. Source area soils are low in extractable Fe, Mn and Al, and characterization by X-ray absorption spectroscopy and electron microscopy indicated that As is present primarily as arsenate sorbed to (alumino)silicate minerals. Batch sorption experiments showed much less sorption on surficial aquifer sediments than on sediments from the Jackson Bluff Formation (JBF), a presumed confining layer. This limited capacity of the surficial aquifer sediments for As sorption is consistent with the similar As contents observed for these sediments within and upgradient of the As plume. The apparent stability of the As plume cannot be explained by sequestration of As within the surficial aquifer. Sorption to JBF sediments may contribute to As sequestration, but As enrichment in JBF sediments within the plume (i.e., as compared with JBF sediments upgradient) was not observed. These results indicate that neither the persistence of As in the source area soils or the apparent stability of the plume of As-contaminated groundwater at this site can be explained by geochemical controls on As mobility. The absence of demonstrable geochemical bases for such observations suggests that possible hydrologic controls should be further investigated at this site.  相似文献   

17.
This study developed methodology for statistically assessing groundwater contamination mechanisms. It focused on microbial water pollution in low-income regions. Risk factors for faecal contamination of groundwater-fed drinking-water sources were evaluated in a case study in Juba, South Sudan. The study was based on counts of thermotolerant coliforms in water samples from 129 sources, collected by the humanitarian aid organisation Médecins Sans Frontières in 2010. The factors included hydrogeological settings, land use and socio-economic characteristics. The results showed that the residuals of a conventional probit regression model had a significant positive spatial autocorrelation (Moran’s I?=?3.05, I-stat?=?9.28); therefore, a spatial model was developed that had better goodness-of-fit to the observations. The most significant factor in this model (p-value 0.005) was the distance from a water source to the nearest Tukul area, an area with informal settlements that lack sanitation services. It is thus recommended that future remediation and monitoring efforts in the city be concentrated in such low-income regions. The spatial model differed from the conventional approach: in contrast with the latter case, lowland topography was not significant at the 5% level, as the p-value was 0.074 in the spatial model and 0.040 in the traditional model. This study showed that statistical risk-factor assessments of groundwater contamination need to consider spatial interactions when the water sources are located close to each other. Future studies might further investigate the cut-off distance that reflects spatial autocorrelation. Particularly, these results advise research on urban groundwater quality.  相似文献   

18.
In the present case study, impact of urbanization and industrial development on the shallow groundwater regime of Saharanpur town of Uttar Pradesh in India is examined with the aim of planning groundwater protection for better governance. The hazardous physicochemical and bacteriological parameters and heavy metals detected in the shallow aquifer include harmful pathogens like fecal coliforms, heavy metals like cadmium, chromium, nitrates and sulphates. An assessment of ground water vulnerability using the well known DRASTIC method has confirmed that the shallow groundwater in some central and southern localities of Saharanpur town fall in the medium risk zones. Further, using field data of 32 electrical resistivity soundings, the protective capacity of the unconfined aquifer is assessed in terms of a ‘total longitudinal conductance’ of the semi-pervious to impervious sediments overlying the unconfined aquifer. However, some areas aligned along a northwest-southeast and in the western parts of the town seem to have relatively higher protective capacity against infiltrating waste pollutants. A ground water protection planning map prepared by combining the DRASTIC map and the ‘potentially hazardous pollutants’ map has brought out the need to install eleven new groundwater quality monitoring wells in the town at locations near the line sources and point sources of pollution. This approach can be readily employed by the decision makers in framing sound guidelines for groundwater protection and governance.  相似文献   

19.
嵇志远  王维玮  文扬 《岩矿测试》2013,32(5):747-752
总大肠菌群和大肠埃希氏菌是表征环境水样中粪便污染的两个重要指标。对这两个指标的检测,传统的多管发酵法和滤膜法已经无法满足快速、准确的检测要求。而近年来能够快速测定的固定酶底物技术(DST)已经在国内开始运用,但是由于其检测成本较高,影响了其在基层实验室的推广,MI琼脂法的出现较好地弥补了这个缺陷。本文应用MI琼脂法检测环境水样中总大肠菌群和大肠埃希氏菌,对其方法性能进行了测试和研究,选择国家标准方法——远藤琼脂法作为比较对象,通过菌种加标回收试验比较MI琼脂法和远藤琼脂法的灵敏度差异,通过实际水样的检测验证MI琼脂法和国标法是否具有等效性。结果表明:使用MI琼脂法检测总大肠菌群和大肠埃希氏菌加标样品的平均回收率分别为89.2%和88.8%,分别高于远藤琼脂法的81.0%和81.2%,证明MI琼脂法的灵敏度高于远藤琼脂法。MI琼脂法和远藤琼脂法检测总大肠菌群和大肠埃希氏菌的相关系数分别为0.9627和0.9511,都具有显著相关性,且检测结果没有统计学意义上的差异,证明两种方法检测总大肠菌群和大肠埃希氏菌具有等效性。与国家标准方法相比,MI琼脂法具有灵敏度高、操作简便、检测周期短、检测成本低、可同时检测两个指标等优点,可以替代传统的滤膜法作为检测总大肠菌群和大肠埃希氏菌的新方法。  相似文献   

20.
This paper evaluates the potential use of a fine-grained soil obtained from a site in West Bengal, India, as a suitable landfill liner material for the containment of hexavalent chromium from tanning waste sludge. The physico-chemical properties of the soil were determined. The soil adsorption affinity for hexavalent chromium was also assessed through adsorption batch and breakthrough column tests. The zero point charge (pHzpc) of the soil was found to be 7.3. The batch kinetics and column tests results indicated that the soil liner possesses a relatively good hexavalent chromium adsorption capacity at natural or slightly alkaline condition. The adsorption results showed that the hexavalent chromium uptake by the soil follows both Langmuir and Freundlich adsorption isotherms. This study also illustrated that the hexavalent chromium breakthrough curve in the column experiment reached equilibrium concentration after 3.5 pore volumes (900 h). Overall, this study showed that the fine-grained soil has the potential for usage as a landfill liner or as a component of a landfill barrier system to prevent chromium contamination from the tannery waste disposal.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号