Routine Water Quality Monitoring Research Articles

Interpolation of extensive routine water pollution monitoring datasets: methodology and discussion of implications for aquifer management.

A large fraction of the fresh water available for human use is stored in groundwater aquifers. Since human activities such as mining, agriculture, industry and urbanisation often result in incursion of various pollutants to groundwater, routine monitoring of water quality is an indispensable component of judicious aquifer management. Unfortunately, groundwater pollution monitoring is expensive and usually cannot cover an aquifer with the spatial resolution necessary for making adequate management decisions. Interpolation of monitoring data is thus an important tool for supplementing monitoring observations. However, interpolating routine groundwater pollution data poses a special problem due to the nature of the observations. The data from a producing aquifer usually includes many zero pollution concentration values from the clean parts of the aquifer but may span a wide range of values (up to a few orders of magnitude) in the polluted areas. This manuscript presents a methodology that can cope with such datasets and use them to produce maps that present the pollution plumes but also delineates the clean areas that are fit for production. A method for assessing the quality of mapping in a way which is suitable to the data's dynamic range of values is also presented. A local variant of inverse distance weighting is employed to interpolate the data. Inclusion zones around the interpolation points ensure that only relevant observations contribute to each interpolated concentration. Using inclusion zones improves the accuracy of the mapping but results in interpolation grid points which are not assigned a value. The inherent trade-off between the interpolation accuracy and coverage is demonstrated using both circular and elliptical inclusion zones. A leave-one-out cross testing is used to assess and compare the performance of the interpolations. The methodology is demonstrated using groundwater pollution monitoring data from the coastal aquifer along the Israeli shoreline. The implications for aquifer management are discussed.

Efficiency evaluation of hydrogen sulfide-producing bacteria as an indicator in the assessment of microbial quality of water sources

Aims: The object of this study was to assess the usefulness of the H 2 S test for detection of fecal pollution of water in comparison to fecal indicator bacteria (FIB). Materials and Methods: A total of 70 raw water samples were collected from drinking water sources in Isfahan province of Iran, aseptically in sterile containers during May-October 2012.The modified H 2 S test medium of Manja et al. was used except that L-cysteine was added as an additional medium component. Total coliforms (TCs), fecal coliforms (FCs), and fecal streptococci (FS) were also estimated by multiple-tube fermentation method. Statistical analyses were carried out using SPSS 20 at the 95% confidence level (α = 0.05). Results: It was found that out of 70 water samples assessed, 48.3%, 30.0%, 34.6%, and 32.9% of the samples were positive for TCs, FCs, FS, and H 2 S, respectively. Analysis of data showed that 95.6%, 69.5%, and 76.9% of water samples, which were positive for H 2 S test were also positive for TCs, FCs, and FS, respectively. The H 2 S test was found to have the highest accuracy for the detection of FS, but it was not a suitable indicator for the prediction of FCs. Conclusions: Our results showed that H 2 S test is not a suitable alternative approach for routine water quality monitoring. However, the H 2 S test could be used as an easy and economic test to assess the quality of drinking water in communities where manpower and sophisticated equipment are inadequate. More laboratory and field studies are required to assess the reliability of the method as an alternative method of traditional indicators.

Development of cost-effective strategies for environmental monitoring of irrigated areas in Mediterranean regions: Traditional and new approaches in a changing world

A series of reliable and cost-effective microbioassay-based techniques for routine water quality monitoring were developed and tested on a recently developed irrigation area in western Spain. Results from these assays were compared to a screening-level risk characterisation based on pesticide concentrations in water samples from the study area. The levels of 147 pesticides were measured in irrigation channels, fluvial water and selected animal (Red swamp crayfish, Procambarus clarkii) and plant (Willow, Salix spp. and Holm Oak, Quercus ilex) tissue. The presence of 59 human and veterinary pharmaceuticals in the watershed was also explored. Mitochondrial activity (tetrazolium salts reduction), lipid peroxidation (thiobarbituric acid method), chlorophyll content (autofluorescence) and total amount of DNA (Hoechst fluorimetry) were evaluated in fern (Soft shield fern, Polystichum setiferum) spores and gametophytes as markers of effects on plant development. Lipid peroxidation was assessed as a measure for acute animal toxicity in zebrafish embryos (Danio rerio). Pollution by pesticides (atrazine, diuron, molinate and oxadiazon) and pharmaceuticals (caffeine, cotinine, ivermectine, nicotine and paraxanthine) was detected in water courses receiving irrigation drainage. Pesticide traces were detected in red swamp crayfish (oxadiazon), and Holm oak leaves (oxadiazon, terbutilazine) but not in willow leaves. Preliminary risk assessment described potential moderate or high risk in the lower waters of both studied rivers. The battery of bioassays was able to detect toxicity in the waters of the lower Gargáligas as well as toxic effects on the waters from the irrigation channel. Such methods could both cut costs and improve the prognostic capability of current monitoring programmes.

Optimization of sampling frequency for routine river water quality monitoring

Sampling frequency is an important factor to be considered during the design of a water monitoring network, and the cost-effective selection of possible ways and means for the optimization of sampling frequency is still needed. This paper introduces water pollution index deviation ratio comparison (WPI DRC), a procedure for the optimization of sampling frequency for a routine river water quality monitoring system. Sampling frequency optimized using WPI DRC at monitoring station X5 in the mainstream of Xiangjiang River is compared with that established using the traditional Statistical Algorithm method. The result of comparison indicates that WPI DRC is more feasible than the traditional one. And then, the sampling frequencies for other 16 monitoring stations also have been optimized, and the results show the sampling frequencies of all the stations except that X4 are reduced, and there is no unacceptable difference between water quality evaluation results at 17 stations before and after the optimization. Therefore, it is concluded that WPI DRC is an effective optimization process with operable results, which can be used to fulfill the requirement of practical monitoring work.

Study on Methods of Water Quality Analysis Based on Conventional Water Quality Monitoring Parameters

Water contamination events of urban water supply often show the characteristics of abruptness and variety, and the on-line water quality monitoring parameters usually are difficult to cover various contaminant parameters. With the help with routine detection and on-line water quality monitoring, it is possible to detect and judge whether a water quality event has happened or not and to identify its type indirectly, and obtain the relevant information of qualitative and quantitative analysis. These will be significant to the decision making by the concerning sectors and units. Taking the events of ammonium iron sulfate in the distribution system for example, the relationship of water between contamination concentration and conventional water quality monitoring parameters is investigated, and the quantitative method based on D-S evidence theory is given.

Ecological Integrity of a Peri-Urban River System, Chiraura River in Zimbabwe

Ecological integrity of a peri-urban river system facing a plethora of anthropogenic pressures was assessed through multivariate analysis of physicochemical parameters correlated to the resident macroinvertebrate community. Monthly collection of macroinvertebrates and concurrent measurement of the physical and chemical parameters (dissolved oxygen concentration, percentage saturation of oxygen, pH, temperature, electrical conductivity and salinity) of water was done over a period of 5 months from November 2011- March 2012 in six sites across the Chiraura River. Macroinvertebrates were collected using the kick-net sampling technique, identified up to family level and enumerated at each site. Biodiversity indices were calculated for each site following the South African Scoring System version 5 (SASS5). A total of 1209 macroinvertebrates belonging to 49 families and11 orders were recorded in the Chiraura River. Most pollution sensitive taxa were found at sites 3 and 4 and the most pollution tolerant families were found at sites 1, 5 and 6. Sites4 and 5 of Chiraura River were the least polluted. Unsustainable anthropogenic activities, including industrial, domestic and urban agricultural activities affects water quality of Chiraura River. This is mainly through run-off and increased effluent to the river making routine water quality monitoring imperative.

A graphene and multienzyme functionalized carbon nanosphere-based electrochemical immunosensor for microcystin-LR detection

A graphene-based immunosensor was fabricated for the detection of microcystin-LR using a horseradish peroxidase–carbon nanosphere–antibody system for signal amplification. Graphene and chitosan were used as immobilization materials to improve the electrochemical performance of the electrode. Signal amplification was achieved using multienzyme functionalized carbon nanosphere. This approach provided a linear range from 0.05 to 15μgL−1 microcystin-LR with a detection limit of 0.016μgL−1. Analytical detection of microcystin-LR in environmental water samples were demonstrated by comparing the results obtained using immunosensor and high-performance liquid chromatography. This electrochemical immunosensor showed good performance with high sensitivity, acceptable stability, repeatability and the potential for use in routine water quality monitoring for various toxins.

The development of a new optical total suspended matter algorithm for the Chesapeake Bay

Sediment loading is one of the primary threats to the health of the Chesapeake Bay. We have developed a high resolution (250m) ocean color satellite tool to monitor sediment concentrations in the Bay. In situ optical and sediment sampling is used to develop a total suspended matter (TSM) algorithm for the Chesapeake Bay. The Coastal Optical Characterization Experiment (COCE) is part of an ongoing effort to optically characterize processes and to develop regional remote sensing ocean color algorithms in the coastal waters. The goal is to characterize sediment concentrations and to develop a tool to track plumes cascading down the Bay following heavy rainfall events. Background TSM concentrations in the Chesapeake Bay Watershed can also be characterized. The plumes can have potentially devastating effects on the Chesapeake Bay's fragile ecosystem by increasing nutrient loads, depositing sediments, and decreasing salinity and light levels. Sampling took place throughout 2006 to 2008 in the upper and mid portions of the Chesapeake Bay. Measurements of TSM, chlorophyll a (Chl), and hyperspectral optics were collected. The optical measurements included above water surface irradiance (Es(λ)), in-water downwelling irradiance (Ed(λ)) and in-water upwelling radiance (Lu(λ)). These optical data were used to analyze the performance and utility of the Moderate Resolution Imaging Spectroradiometer (MODIS) Aqua Band 1 (645nm) for use as a TSM monitoring tool. From the optical measurements we have derived a 3rd order polynomial regression of TSM to normalized water-leaving radiance (r2=0.79) to form an algorithm that quantitatively relates TSM to the MODIS 250m resolution band 1 (645nm). The algorithm performance was validated (a mean percent difference of −4.2%) against 270 total suspended solids samples collected by the Chesapeake Bay Program during routine water quality monitoring of the Chesapeake Bay environment. The TSM algorithm tool is then used to demonstrate monitoring of significant runoff events that occurred in June, 2006 and March, 2008. In addition, the utility of the Chesapeake Bay TSM product is demonstrated by describing regional and seasonal variations in sediment concentrations throughout the Chesapeake Bay for 2009. Mean concentrations ranged from 11.55mg/l in the upper Chesapeake Bay winter season to 6.37mg/l in the middle Chesapeake Bay spring season. These remote sensing tools can be valuable instruments in the detection and tracking of runoff events and background concentration for monitoring the health and recovery of the Chesapeake Bay.

Rapid and specific detection of Salmonella in water samples using real-time PCR and High Resolution Melt (HRM) curve analysis

A real-time PCR assay combined with a pre-enrichment step for the specific and rapid detection of Salmonella in water samples is described. Following amplification of the invA gene target, High Resolution Melt (HRM) curve analysis was used to discriminate between products formed and to positively identify invA amplification. The real-time PCR assay was evaluated for specificity and sensitivity. The assay displayed 100% specificity for Salmonella and combined with a 16-18 h non-selective pre-enrichment step, the assay proved to be highly sensitive with a detection limit of 1.0 CFU/ml for surface water samples. The detection assay also demonstrated a high intra-run and inter-run repeatability with very little variation in invA amplicon melting temperature. When applied to water samples received routinely by the laboratory, the assay showed the presence of Salmonella in particularly surface water and treated effluent samples. Using the HRM based assay, the time required for Salmonella detection was drastically shortened to less than 24 h compared to several days when using standard culturing methods. This assay provides a useful tool for routine water quality monitoring as well as for quick screening during disease outbreaks.

Sustainable microbial water quality monitoring programme design using phage-lysis and multivariate techniques

Contamination of surface waters is a pervasive threat to human health, hence, the need to better understand the sources and spatio-temporal variations of contaminants within river catchments. River catchment managers are required to sustainably monitor and manage the quality of surface waters. Catchment managers therefore need cost-effective low-cost long-term sustainable water quality monitoring and management designs to proactively protect public health and aquatic ecosystems. Multivariate and phage-lysis techniques were used to investigate spatio-temporal variations of water quality, main polluting chemophysical and microbial parameters, faecal micro-organisms sources, and to establish ‘sentry’ sampling sites in the Ouse River catchment, southeast England, UK. 350 river water samples were analysed for fourteen chemophysical and microbial water quality parameters in conjunction with the novel human-specific phages of Bacteroides GB-124 (Bacteroides GB-124). Annual, autumn, spring, summer, and winter principal components (PCs) explained approximately 54%, 75%, 62%, 48%, and 60%, respectively, of the total variance present in the datasets. Significant loadings of Escherichia coli, intestinal enterococci, turbidity, and human-specific Bacteroides GB-124 were observed in all datasets. Cluster analysis successfully grouped sampling sites into five clusters. Importantly, multivariate and phage-lysis techniques were useful in determining the sources and spatial extent of water contamination in the catchment. Though human faecal contamination was significant during dry periods, the main source of contamination was non-human. Bacteroides GB-124 could potentially be used for catchment routine microbial water quality monitoring. For a cost-effective low-cost long-term sustainable water quality monitoring design, E. coli or intestinal enterococci, turbidity, and Bacteroides GB-124 should be monitored all-year round in this river catchment.

Spatial variation of waterborne Escherichia coli – implications for routine water quality monitoring

Escherichia coli are often used as faecal indicator bacteria (FIB) to provide a measure of microbial pollution in recreational and shellfish harvesting waters. However, although model forecasts for predicting the concentrations of FIB in surface waters are becoming more robust, they suffer from an inconsistency in quantification methods and an understanding of the spatial variation of FIB within a water course. The aim of this study was to investigate the transverse spatial variation in E. coli numbers (as an indicator of faecal pollution) across the estuary of the River Conwy, UK. Water samples were collected from four transverse transects across the estuary. Spatial variation of E. coli was significantly different from one side of the river to the other, although was not correlated with depth or the physiochemical properties of the water. Subsequently, microbial water quality classifications on the two opposite banks suggested very different levels of pollution coming down the river. This work has shown that the side of the river that routine water monitoring samples are taken from can make a significant difference to the classification of microbial water quality. This has important implications for sampling strategies and the use of microbial source tracking (MST) techniques.

Integrated Online System for a Pyrosequencing-Based Microbial Source Tracking Method that Targets Bacteroidetes 16S rDNA

Genotypic microbial source tracking (MST) methods are now routinely used to determine sources of fecal contamination impacting waterways. We previously reported the development of a pyrosequencing-based MST method that assigns contamination sources based on shared operational taxonomic units (OTUs) between fecal and environmental bacterial communities. Despite decreasing sequencing costs, pyrosequencing-based MST approaches are not used in routine water quality monitoring studies due in large part to difficulties in handling massive data sets and difficulties in determining sources of fecal contamination. In the studies presented here we describe the development of an online MST tool, PyroMiST ( http://env1.gist.ac.kr/∼aeml/MST.html) that uses total bacterial or Bacteroidetes 16S rDNA pyrosequencing reads to determine fecal contamination of waterways. The program cd-hit was used for OTU assignment and a Perl script was used to calculate the number of shared OTUs. The analyses require only a small number of pyrosequencing reads from environmental samples. Our results indicate that PyroMiST provides a user-friendly web interface for pyrosequence data that significantly reduces analysis time required to determine potential sources of fecal contamination in the environment.

NOTE: Stream diversion management to improve water quality in a Connecticut water supply reservoir

Managing raw water quality in drinking water reservoirs with the goal of reducing treatment costs and producing high quality finished water can involve a number of watershed and in-lake based approaches. Some water supply impoundment systems have structural controls that can vary the timing of water diversion from one or more subwatersheds. Water from approximately 77% of the watershed for the South Central Connecticut Regional Water Authority's (SCCRWA) Lake Saltonstall reservoir is accessed through a man-made diversion on the Farm River in East Haven, Connecticut. Watershed land uses include cropland, dairy farms and urban–suburban development. Operational data for the Farm River diversion indicate that water was diverted to the reservoir for 54% of the period from 1993 through 2002 and for 21% of the period that followed from 2003 through 2008. From 2001 through 2008, routine monitoring of reservoir water quality exhibited improving trends in Secchi depth, turbidity, chlorophyll a, color and total phosphorus. The measurable improvement in reservoir water quality seems to have resulted from active management of the stream diversion, which includes avoiding use during storm flows or when water system storage is safely above levels needed to meet customer demands. The benefits of this strategy for public water supplies are evident, but there are both positive and negative potential implications for instream flow management. Balancing multiple and often competing factors associated with water supply management requires the ability to implement operational practices that are both flexible and responsive.

Non-indigenous macroinvertebrate species in Lithuanian fresh waters, Part 2: Macroinvertebrate assemblage deviation from naturalness in lotic systems and the consequent potential impacts on ecological quality assessment

The biological pressure represented by non-indigenous macroinvertebrate species (NIMS) should be addressed in the implementation of EU Water Framework Directive as this can have a direct impact on the ’naturalness’ of the invaded macroinvertebrate assemblage. The biocontamination concept allows assessment of this deviation from naturalness, by evaluation of abundance and disparity contamination of an assemblage. This study aimed to assess the biocontamination of macroinvertebrate assemblages in Lithuanian rivers, thereby revealing the most high-impact non-indigenous species, and to explore the relationship between biocontamination and conventional metrics of ecological quality. Most of the studied rivers appeared to be impacted by NIMS. The amphipods Pontogammarus robustoides, Chelicorophium curvispinum and snail Litoglyphus naticoides were revealed as high-impact NIMS for Lithuanian lotic systems. Metrics of ecological quality which largely depend upon the richness of indicator taxa, such as the biological monitoring working party (BMWP) score and Ephemeroptera/Plecoptera/Trichoptera (EPT) taxa number, were negatively correlated with biocontamination, implying they could provide unreliable ecological quality estimates when NIMS are present. Routine macroinvertebrate water quality monitoring data are sufficient for generation of the biocontamination assessment and thus can provide supplementary information, with minimal extra expense or effort. We therefore recommend that biocontamination assessment is included alongside established methods for gauging biological and chemical water quality.

Improved detection and quantitation of norovirus from water

Norovirus is associated commonly with human sewage and is responsible for numerous cases of waterborne and foodborne gastroenteritis every year. Assays using reverse transcription-quantitative polymerase chain reaction (RT-qPCR) have been developed for norovirus, however, accurate detection and quantitation remain problematic owing to a lack of suitable positive controls. To improve enumeration of norovirus genomes from water, a synthetic norovirus genogroup II quantitation standard and competitive internal positive control were developed. The quantitation standard demonstrates identical amplification efficiency as wildtype norovirus and can be used as a viral surrogate in labs with restricted access to norovirus. The internal control quantifies sample inhibition, allowing for accurate quantitation of norovirus from complex environmental samples. Seawater samples spiked with sewage or bird guano were evaluated using the norovirus assay as part of a methods comparison study. Inhibition was detected in nine of 36 (25%) samples, two of which proved to be positive upon re-analysis. Results support the specificity of this assay for human-source (sewage) fecal contamination. Overall, use of this quantitation standard and internal control signify a great advance over traditional positive controls and suggest that molecular techniques for viral analysis could become standardized for routine water quality monitoring.

Sorbitol-fermenting Bifidobacteria are indicators of very recent human faecal pollution in streams and groundwater habitats in urban tropical lowlands.

Sorbitol-fermenting Bifidobacteria (SFB) proved to be an excellent indicator of very recent human faecal pollution (hours to days) in the investigated tropical stream and groundwater habitats. SFB were recovered from human faeces and sources potentially contaminated with human excreta. SFB were undetectable in animal faeces and environmental samples not contaminated with human faeces. Microcosm studies demonstrated a rapid die-off rate in groundwater (T90 value 0.6 days) and stream water (T90 value 0.9-1.7 days). Discrimination sensitivity analysis, including E. coli, faecal coliforms, total coliforms and Clostridium perfringens spores, revealed high ability of SFB to distinguish differing levels of faecal pollution especially for streams although high background levels of interfering bacteria can complicate its recovery on the used medium. Due to its faster die-off, as compared to many waterborne pathogens, SFB cannot replace microbiological standard parameters for routine water quality monitoring but it is highly recommendable as a specific and complementary tool when human faecal pollution has to be localized or verified. Because of its exclusive faecal origin and human specificity it seems also worthwhile to include SFB in future risk evaluation studies at tropical water resources in order to evaluate under which situations risks of infection may be indicated.

Evaluating the effectiveness of routine water quality monitoring in Miyun reservoir based on geostatistical analysis

This study used geographic information system techniques and geostatistics methods to evaluate the effectiveness of routine water quality monitoring in the western segment of the Miyun reservoir in Beijing. Methodologies as well as the sampling design are evaluated. The single-layer evaluation and three integrated evaluation methods including principal component analysis (PCA), ordinary kriging (OK)_Mean, and Mean_Layers were used to validate the effectiveness of evaluation methods, and the effectiveness of each sampling design was validated by comparing their errors. Results indicated that, while a single-layer evaluation only shows the trophic state of water at a specific level, an integrated evaluation synthetically analyzes and evaluates the trophic state of the entire water body. Furthermore, results of the integrated analysis show that a PCA method is more accurate and can represent the trophic state of the entire water body. The OK_Mean and Mean_Layers methods are only able to represent the mean level for trophic state of the entire water body but cannot reflect local trophic state and distribution details. Although methods used in the routine monitoring of Miyun reservoir have some similarities to the OK_Mean and Mean_Layers methods, their range of errors and uncertainty are greater because of a lack of detailed spatial continuous information. The analysis on the number of sampling points shows that, within a certain range of error, minor changes of sampling points will have no obvious impact on the monitoring results. For the routine monitoring of western Miyun reservoir, using only three to five sampling points for monitoring is inadequate. According to our analysis, it is more appropriate to use at least ten sampling points for monitoring these areas.

An appraisal of a biocontamination assessment method for freshwater macroinvertebrate assemblages; a practical way to measure a significant biological pressure?

Freshwater invasive or alien species (IAS) can have a major impact on benthic macroinvertebrate assemblage structure and diversity. This has implications for accurate biological monitoring, the assessment of the ecological quality status of rivers and achievement of Water Framework Directive (WFD) objectives. Although IAS constitutes a major biological pressure to WFD objectives, current approaches to ecological status assessment tend to ignore their presence. This problem is compounded as biotic indices such as the Biological Monitoring Working Party (BMWP) score do not distinguish between native and IAS, when IAS tend to be more tolerant of organic pollution than the natives they replace. Biocontamination is the presence of an IAS in a system, and we tested a new method of biocontamination assessment, designed to be used alongside current routine water quality monitoring techniques, by applying it to biological monitoring data from the river monitoring programme of a small Island, The Isle of Man. Although 54% of monitoring sites exhibited no biocontamination, 19% showed low or moderate biocontamination and 27% high or severe biocontamination. Richness contamination was low (only two contaminated families being recorded), but abundance contamination was high in some sites (87% of individuals being IAS). Sites with a greater relative abundance of IAS individuals exhibited lower BMWP water quality. Within invaded sites BMWP monitoring was not responsive to changing chemical water quality, whereas within uninvaded sites it was. In invaded sites, the relative abundance of IAS increased as ammonia and BOD5 increased. Our study shows current monitoring approaches mask the presence of AIS within assemblages, with some highly biocontaminated sites registering high BMWP biological quality. This new index represents a simple way to integrate the IAS biological pressure into established WFD monitoring programmes, to produce more comprehensive estimates of ecological quality status than are currently being realised.

Persistence of nucleic acid markers of health-relevant organisms in seawater microcosms: Implications for their use in assessing risk in recreational waters

In the last decade, the use of culture-independent methods for detecting indicator organisms and pathogens in recreational waters has increased and has led to heightened interest in their use for routine water quality monitoring. However, a thorough understanding of the persistence of genetic markers in environmental waters is lacking. In the present study, we evaluate the persistence of enterococci, enterovirus, and human-specific Bacteroidales in seawater microcosms. Two microcosms consisted of seawater seeded with human sewage. Two additional seawater microcosms were seeded with naked Enterococcus faecium DNA and poliovirus RNA. One of each replicate microcosm was exposed to natural sunlight; the other was kept in complete darkness. In the sewage microcosms, concentrations of enterococci and enterovirus were measured using standard culture-dependent methods as well as QPCR and RT-QPCR respectively. Concentrations of human-specific Bacteroidales were determined with QPCR. In the naked-genome microcosms, enterococci and enterovirus markers were enumerated using QPCR and RT-QPCR, respectively. In the sewage microcosm exposed to sunlight, concentrations of culturable enterococci fell below the detection limit within 5 days, but the QPCR signal persisted until the end of the experiment (day 28). Culturable enterococci did not persist as long as infectious enteroviruses. The ability to culture enteroviruses and enterococci was lost before detection of the genetic markers was lost, but the human-specific Bacteroidales QPCR signal persisted for a similar duration as infectious enteroviruses in the sewage microcosm exposed to sunlight. In the naked-genome microcosms, DNA and RNA from enterococci and enterovirus, respectively, persisted for over 10 d and did not vary between the light and dark treatments. These results indicate differential persistence of genetic markers and culturable organisms of public health relevance in an environmental matrix and have important management implications.

Water quality monitoring in a slightly-polluted inland water body through remote sensing — Case study of the Guanting Reservoir in Beijing, China

This study focused on the water quality of the Guanting Reservoir, a possible auxiliary drinking water source for Beijing. Through a remote sensing (RS) approach and using Landsat 5 Thematic Mapper (TM) data, water quality retrieval models were established and analyzed for eight common water quality variables, including algae content, turbidity, and concentrations of chemical oxygen demand, total nitrogen, ammonia nitrogen, nitrate nitrogen, total phosphorus, and dissolved phosphorus. The results show that there exists a statistically significant correlation between each water quality variable and remote sensing data in a slightly-polluted inland water body with fairly weak spectral radiation. With an appropriate method of sampling pixel digital numbers and multiple regression algorithms, retrieval of the algae content, turbidity, and nitrate nitrogen concentration was achieved within 10% mean relative error, concentrations of total nitrogen and dissolved phosphorus within 20%, and concentrations of ammonia nitrogen and total phosphorus within 30%. On the other hand, no effective retrieval method for chemical oxygen demand was found. These accuracies were acceptable for the practical application of routine monitoring and early warning on water quality safety with the support of precise traditional monitoring. The results show that performing the most traditional routine monitoring of water quality by RS in relatively clean inland water bodies is possible and effective.