An assessment of the potential adverse properties of fluorescent tracer dyes used for groundwater tracing

The potential ecotoxicity of fluorescent dyes used in tracing, and their possible effects on human health, were evaluated by reviewing available toxicological information for 12 dyes — fluorescein, Lissamine Flavine FF, Rhodamine WT, Rhodamine B, Sulpho Rhodamine G, Sulpho Rhodamine B, eosin, pyranine, Phorwite BBH Pure, Tinopal 5BM GX, Tinopal CBS-X, and Diphenyl Brilliant Flavine 7GFF — and a dye-intermediate, amino G acid. This evaluation used available toxicological information, test data on analogous substances, and mathematical expressions for biological activity. Based on set criteria for human health and acute ecotoxicity, the evaluation indicated that these tracers have low to moderate levels of concern. The use of these tracers for the study of groundwater flow is appropriate if consideration is given to the overall human health and environmental effects. Their use in the environment requires tracer concentrations not exceeding 1–2 mg 1^–1 persisting for a period in excess of 24 h in the groundwater at the point of groundwater withdrawal or discharge. A simple calculated potential dose was used in a comparison of the estimated acute toxicity of Rhodamine WT in rats to the known acute oral toxic dose in humans for several known acutely toxic chemicals. This comparison showed that none of the fluorescent dyes evaluated would present an acutely toxic threat at or substantially above the recommended 2 mg 1^–1 concentration.The U.S. Governments right to retain a non-exclusive, royalty free licence in and to any copyright is acknowledged. Disclaimer: The views of this paper are solely those of the authors and do not necessarily reflect the views or policies of the U.S. Environmental Protection Agency.     

Bioaerosol characterization by flow cytometry with fluorochrome

Traditional culture and microscopy methods for evaluation of bioaerosols are slow, tedious, and rather imprecise. In this study, the application of flow cytometry that was combined with a fluorescent technique (FCM/FL) was evaluated as a technique to quickly and accurately determine and quantify the total concentration and viability of bioaerosols. The optimal conditions of five fluorescent dyes [acridine orange (AO), SYTO-13, propidium iodide (PI), YOPRO-1, and 5-cyano-2,3-ditolytetrazolium chloride (CTC)] used in FCM/FL were determined for laboratory samples of bacterial aerosols (Escherichia coli, and endospores of Bacillus subtilis) and fungal aerosols (Candida famata and Penicillium citrinum spores). Based on the measured cell concentration, fluorescence intensity, and staining efficiency as indicators for dye performance evaluation, SYTO-13 was found to be the most suitable fluorescent dye for determining the total concentration of the bioaerosols, as well as YOPRO-1 was the most suitable for determining viability. Moreover, the established optimal FCM/FL with dyes was validated for characterizing microorganism profiles from both air and water samples from the aeration tank of hospital wastewater treatment plant. In conclusion, the FCM/FL successfully assessed the total concentration and viability for bacterial and fungal microorganisms in environmental field samples.     

Evaluation of ground water denitrification at a biosolids disposal site

A study was conducted at a sanitary sewage sludge(biosolids) disposal site in Springfield, Illinois, U.S.A. todetermine if biological denitrification played a significantfactor in attenuation of ground water nitrate values. The siteselected for this study is a 23 ha (57 acre) dedicatedbiosolids disposal facility located adjacent to a 75.7 millionliter per day (20 million gallons per day) municipal treatmentplant that uses anaerobic solids stabilization for treatment ofgenerated biosolids material. Biosolids have been disposed of byfixed-point spray applicators at the site since 1976, which hascaused ground water nitrate levels to increase significantlyabove background levels. A method was developed using aconservative chemical tracer to simulate the biosolidsapplication process and monitor the ground water directly beneaththe simulated disposal site. Results demonstrated a net declineof nitrates that could not be attributed to dilution alone.While the monitoring methodology developed for this study didnot directly estimate the denitrification rate, a rate foroverall nitrate reduction was calculated that could be consideredto take into account all transport and reduction mechanisms suchas denitrification, advection, dispersion and dilution.     

A field-based spectrophotometric flow-injection system for automatic determination of chloride in soil water

The use of chloride as a tracer for soil water investigations is discussed. Limitations with laboratory based soil core and field based sampling are considered with respect to the poor suitability of the data for rigorous assessment of mechanistic models. Investigation of water movement in soil has been restricted by limitations in spatial and temporal sampling. Fine resolution sampling generates large numbers of samples which cause problems with post sampling laboratory analysis. This paper describes a field-based system for the analysis of chloride in soil water. There are three component parts to the system, (i) a custom sampling sub-system comprising of ceramic cup suction samplers and sample traps, (ii) a sample routing sub-system to channel sample to (iii) a sample analysis sub-system utilizing a flow injection method for sample analysis using a custom built photo-diode detector. The three sub-systems were controlled by a suitably equipped personal computer. A calibration procedure is described with a third order polynomial equation derived to convert millivolt response from the detector into chloride concentration. Field and laboratory data from a tracer experiment are presented and discussed, and it is concluded that the system is well suited to field-based applications. Finally it is noted that the photo-detector is suitable for colourimetric analysis of any tracer with suitable chemical determination.     

Simultaneous determination of binary solution of triphenylmethane dyes in complex matrices onto magnetic amino-rich SWCNT using second-order calibration method

This study suggested a new method for simultaneous quantification of two dyes in complex matrices using second-order data by spectrophotometry. Second-order data was generated simply without any expensive instrument using two independent variables including wavelength and the monotonic addition of sodium dodecyl sulfate. Solid-phase extraction (SPE) based on amino-rich magnetic single-walled carbon nanotube as an adsorbent was employed prior to second-order data generation. SPE optimization was performed by Box-Behnken design, and parameters and their interaction which were dependent on the simultaneous extraction of dyes were examined. Competitive Langmuir and Freundlich isotherms for a binary system and individual dyes could all represent the equilibrium data well. The second-order data was processed by parallel factor analysis (PARAFAC and PARAFAC2) and multivariate curve resolution-alternating least squares (MCR-ALS). Figures of merit of the model including a limit of detection of 3.0 and 2.5 ng mL^?1 for crystal violet and malachite green, respectively, were estimated using the MCR-ALS method. The combination of the second-order calibration and SPE presents an easy and versatile method for determination of the mixture of two dyes in the presence of uncalibrated interferences in environmental water, synthetic, and fish samples with the recoveries of 94–104.     

Mapping chlorophyll-a through in-situ measurements and Terra ASTER satellite data

This paper presents an application of water quality mapping through real-time satellite and ground data. The Lake Beysehir which is the largest freshwater lake and drinking water reservoir in Turkey was selected as the study area. Terra ASTER satellite image is used as remote sensing data source for water quality mapping in addition to simultaneously performed in-situ measurements. Ground data is collected simultaneously with the ASTER overpass on June 09, 2005 over the Lake Beysehir. The spatial distribution map is developed by using multiple regression (MR) technique for water quality parameter, which is chlorophyll-a (chl-a). The results indicate that simultaneous ground and satellite remote sensing data are highly correlated (R (2) > 0.86). In the image processing step, geometric correction, image filtering and development of water quality map procedures are performed with the ERDAS Imagine and ArcGIS 9.0 software. The trophic status of Lake Beysehir is considered to be oligotrophic with an average 1.55 microg/l chl-a concentration.     

A Generalized Analytical Model for Crosswind-Integrated Concentrations with Ground-Level Deposition in the Atmospheric Boundary Layer

A generalized mathematical model describing the crosswind-integrated concentrations is presented for dispersion of pollutants emitted from a continuous source in the atmospheric boundary layer with deposition to the ground surface. The model is based on a solution of the resulting two-dimensional steady state advection-diffusion equation with deposition to the ground surface. It considers the horizontal wind speed as a generalized function of vertical height above the ground surface and eddy diffusivity as a function of both downwind distance from the source and vertical height. Various special cases of the model are deduced. A sensitivity analysis of the model prediction of the ground-level crosswind-integrated concentrations with deposition velocity is performed. Various issues and limitations associated with this work are discussed. The model is evaluated with the observations of a depositing tracer obtained from Hanford dual diffusion experiment in stable conditions. The statistical measures show that the present model, by considering deposition, is performing well with the observations. The model is giving an over-predicting trend with the observations and predicts 100 % cases within a factor of two. On the other hand, the consideration of a non-depositing condition for a depositing tracer yields the severe over-prediction and thus, it introduces the significant errors in the model prediction. The selection of the lower boundary condition for a depositing tracer at the height of deposition surface gives better prediction than those at a height of surface roughness length.     

Modelling Tracer Dispersion from Landfills

Several wind tunnel experiments of tracer dispersion from reduced-scale landfill models are presented in this paper. Different experimental set-ups, hot-wire anemometry, particle image velocimetry and tracer concentration measurements were used for the characterisation of flow and dispersion phenomena nearby the models. The main aim of these experiments is to build an extensive experimental data set useful for model validation purposes. To demonstrate the potentiality of the experimental data set, a validation exercise on several mathematical models was performed by means of a statistical technique. The experiments highlighted an increase in pollutant ground level concentrations immediately downwind from the landfill because of induced turbulence and mean flow deflection. This phenomenon turns out to be predominant for the dispersion process. Tests with a different set-up showed an important dependence of the dispersion phenomena from the landfill height and highlighted how complex orographic conditions downwind of the landfill do not affect significantly the dispersion behaviour. Validation exercises were useful for model calibration, improving code reliability, as well as evaluating performances. The Van Ulden model proved to give the most encouraging results.     

Use of cluster and principal component analyses to profile areas in California where ground water has been contaminated by pesticides

An empirical approach to profiling areas of ground water contamination by pesticides was devised that did not rely upon determining the level of vulnerability between land areas and that did not assume any particular pathway for ground water contamination. Climatic and soil data were obtained for 1-square mile sections of land in California where pesticide residues had been found in well water samples and the detection was attributed to legal agricultural applications. These sections were designated as known contaminated (KC) sections. Climate and soil data were also obtained for sections which lacked either well sampling data or a positive pesticide detection. These sections were designated as candidate sections. Statistical procedures were used to cluster groups of KC sections first with respect to climate characteristics and then with respect to soil characteristics. Principal components analysis (PCA) was used to construct a statistical profile of soil variables for each cluster of KC sections. A method based on the PCA was developed to compare the similarity of soil profiles derived for each KC section cluster to individual candidate sections. Since the profiling scheme was based only on data from KC sections, candidate sections that did not match any KC cluster profile could only be considered dissimilar to contaminated sections, receiving a status of not-classified. This profiling method is flexible and it can be revised to incorporate updated well sampling information.     

Mapping Turbidity in the Charles River, Boston Using a High-resolution Satellite

The usability of high-resolution satellite imagery for estimating spatial water quality patterns in urban water bodies is evaluated using turbidity in the lower Charles River, Boston as a case study. Water turbidity was surveyed using a boat-mounted optical sensor (YSI) at 5 m spatial resolution, resulting in about 4,000 data points. The ground data were collected coincidently with a satellite imagery acquisition (IKONOS), which consists of multispectral (R, G, B) reflectance at 1 m resolution. The original correlation between the raw ground and satellite data was poor (R2 = 0.05). Ground data were processed by removing points affected by contamination (e.g., sensor encounters a particle floc), which were identified visually. Also, the ground data were corrected for the memory effect introduced by the sensor's protective casing using an analytical model. Satellite data were processed to remove pixels affected by permanent non-water features (e.g., shoreline). In addition, water pixels within a certain buffer distance from permanent non-water features were removed due to contamination by the adjacency effect. To determine the appropriate buffer distance, a procedure that explicitly considers the distance of pixels to the permanent non-water features was applied. Two automatic methods for removing the effect of temporary non-water features (e.g., boats) were investigated, including (1) creating a water-only mask based on an unsupervised classification and (2) removing (filling) all local maxima in reflectance. After the various processing steps, the correlation between the ground and satellite data was significantly better (R2 = 0.70). The correlation was applied to the satellite image to develop a map of turbidity in the lower Charles River, which reveals large-scale patterns in water clarity. However, the adjacency effect prevented the application of this method to near-shore areas, where high-resolution patterns were expected (e.g., outfall plumes).     

Environmental quality assessment of Port Blair in Andaman islands

The Andman and Nicobar archipelago comprises of about 556 small and big islands covering an area of 8493 sq. kms in the Bay of Bengal. The very remoteness of these islands from the mainland has preserved their pristine environment and spectacular natural beauty. The Andman and Nicobar Administration is going for major developmental projects to cope with the increasing needs of the people, which ultimately results in significant changes in environmental quality. This paper describes the existing environmental quality around Port Blair city, which will give baseline scenario to assess the environmental impacts due to developments in the future.In order to monitor the air quality of the region, sampling stations were selected based on the locations of various industries and domestic activities. Suspended Particulate Matter (SPM), Sulphur dioxide (SO₂) and Nitrogen Oxides (NOx) were monitored for a period of one month during winter season. In addition, micrometeorological data, viz. wind speed and direction were also recorded and analysed to obtain the representative meteorological scenario of the air basin. The monitored values of ambient air quality was found to be within the NAAQ standards of India.Similarly, noise levels were also measured at various locations viz., residential areas, commercial centres, villages, stone quarry sites and construction sites. Noise levels were found to exceed the standards at stone quarry, construction sites and other locations.Water quality studies were carried out with respect to surface and ground water. The various physico- chemical and bacteriological parameters were analysed. It was observed that the physico-chemical parameters of surface and ground water lie within the standards stipulated for Indian subcontinent except for heavy metals which exceed the limits in ground water samples. Bacteriological analysis of sea water and ground water indicate that they are contaminated with faecal matters. Further, the ground water can be used for drinking purposes only after adequate treatment.     

某粉煤灰堆放场对周围岩溶地下水的影响分析

结合粉煤灰堆放场的水文地质状况,通过稳定同位素示踪、浸溶和淋溶试验,探讨了灰场对周围岩溶地下水的影响。结果表明,堆场灰水已经达到下游部分水井,堆场在大气降水和冲灰水的浸泡、淋溶作用下,其中的Cr6+、F-和钙镁盐类大量析出并随灰水一起下渗,石灰岩碎石虽对氟化物有一定的吸附作用,但能力有限。根据试验数据分析认为,该粉煤灰堆放场是焦作市北中部岩溶地下水Cr6+、F-和总硬度升高的主要原因。     

Qualitative time trend analysis of ground water monitoring networks

The detection of significant (short-term) time trends is one of the major goals of ground water monitoring networks. These trends can be used to recognize active geochemical processes and potential environmental threats. This paper presents a case history of time trend analysis on macrochemical parameters of ground water quality. It shows the difficulties and traps that are generally encountered in such studies. The data used originated from the Dutch National Groundwater Quality Monitoring Network. This network is operative since 1979, and keeps track of the ground water composition at 350 locations at two depths (ca. 10 and 25 m below surface; general density, one location per 100 km²). Prior to the trend analysis the data set was divided into geochemically homogeneous groups using fuzzy c-means clustering. Each group represents a specific ground water type, characterized by a distinct source (seawater, surface water or precipitation) and a unique combination of dominant geochemical processes (e.g. mineralization of organic matter, carbonate dissolution and cation exchange).To study trends qualitatively, the concentrations of the various macro-constituents in ground water are correlated with time of sampling. The nonparametric and outlier insensitive Spearman rank correlation coefficient is computed per well screen. A frequency distribution of correlation coefficients is formed by combining the Spearman correlation coefficients of all individual wells within a homogeneous group. This distribution is tested for trends against the appropriate theoretical distribution of zero correlation by use of the Kolmogorov-Smirnov one-sample test. The type of trend is derived from the shape of the distribution.Most ground water types show statistically significant qualitative trends, of which many, however, are caused by changes in the sampling and analytical procedures over the monitoring period. After elimination of differences in limits of detection for NO₃, total-P, and NH₄, most trends in these compounds disappeared. In some water types trends for alkalinity, apparent trends for pH, Ec, and total-P are caused by variations in the laboratory practice, e.g. varying storage procedures, leading to erroneous analyses. Other parameters showed statistically significant trends, related to geochemical processes.The most interesting and most substantial trends are observed in the water type characterized by infiltrating rainwater with agricultural pollutants. In this water type the lowering ground water table induces lower rates of evapotranspiration, giving lower concentrations in time of conservative parameters (Cl, Na, Ca). The aerated zone is enlarged, resulting in increased oxidation of organic material, less efficient nutrient (NO₃, K) uptake by plant roots, leading to increased ground water concentrations of nutrients. In other water types trends are quantitatively small. However, trends are not necessarily linear, and all should be closely monitored in future.     

长江口南通地区农村集中式饮用水源水质状况调查

对南通市24座乡镇地表水厂以及199座乡镇地下水厂的水源水质状况进行了调查.结果表明,地表水水源地中有14座水厂达标,其取水量占地表水取水总量62.8%.水体中主要污染物是NH3-N、石油类、Imn.全市乡镇地下水厂饮用水源水质达标水厂为56座,其取水量占地下水取水总量的26.2%.全市地下水中主要污染物为NH3-N、...     

Ground water discharge and the related nutrient and trace metal fluxes into Quincy bay,Massachusetts

Measurement of the rate and direction of ground water flow beneath Wollaston Beach, Quincy, Massachusetts by use of a heat-pulsing flowmeter shows a mean velocity in the bulk sediment of 40 cm d^–1. The estimated total discharge of ground water into Quincy Bay during October 1990 was 1324–2177 m³ d^–1, a relatively low ground water discharge rate. The tides have only a moderate effect on the rate and direction of this flow. Other important controls on the rate and volume of ground water flow are the limited thickness, geographic extent, and permeability of the aquifer. Comparisons of published streamflow data and estimates of ground water discharge indicate that ground water makes up between 7.4–12.1% of the gaged freshwater input into Quincy Bay. The data from this study suggest the ground water discharge is a less important recharge component to Quincy Bay than predicted by National Urban Runoff Program (NURP) models.The high nitrate and low nitrite and ammonia concentrations in the ground water at the backshore well sites and low nitrate and high nitrite and ammonia concentrations in the water flowing from the foreshore suggests that denitrification is active in the sediments. The low ground water flow rates and low nitrate concentrations in the foreshore samples suggest that little or no nitrate is surviving the denitrification process to affect the planktonic community. Similarly, oxidizing conditions in the aquifer and low trace metal concentrations in the ground water samples suggest that the metals may be precipitating and binding to sedimentary phases before impacting the bay.     

原广州氮肥厂地块地下水环境质量评价

对原广州氮肥厂遗留地块浅层地下水环境质量进行调查与评价。结果表明,其整个地块浅层地下水被污染,特别是硫酸车间和造气车间为地下水污染最重区域。主要污染项目为Mn、NH3-N、亚硝酸盐、Fe、总硬度、IMn、SO2-、F-。提出,在作土壤开挖、修复和新建工程项目过程中,工程施工排水应处理后方可排放,以减少对周围环境水体的影响;建筑工人应避免直接接触地下水,施工时佩带手套,做好保护措施,减少皮肤暴露。     

差压式BOD5测定法的评价研究

对BOD5的测压法测定进行了评价,探讨了该法对接种量的特殊要求;比较了含毒物水样不同稀释比BOD5测定的区别,从而验证了该测定法可用以表征毒性物质对微生物活性的影响程度.通过模拟含毒印染废水活性污泥的处理,指出其不同稀释比BOD5值可作为该处理法的设计和运行管理的重要参数.     

The effects of application of phosphatic fertilizer on cadmium concentration in ground waters around vineyards of Hyderabad

Cadmium is an important contaminant of superphosphate. Market samples of superphosphate revealed a concentration of cadmium in the range of 18.2–28.5 mg/kg. Application of periodic excess doses of superphosphate in vineyards 5–35 years old has led to elevated concentrations of cadmium in the ground water in the vineyards. Ground water samples from different vineyards analysed for cadmium by atomic absorption spectrophotometry revealed concentrations of cadmium in the range of 3.2–99.2 µg/I. These concentrations of cadmium in the ground water can be regarded as significant, since ground water serves as the only source of water for the vineyards.     

大体积水中痕量POPs的联动采集装置及其性能评价

天然水体中的痕量持久性有机污染物(POPs)的定量分析通常需要采集大体积水样.针对大体积水样在过滤和吸附富集过程中滤膜易堵塞且耗时费力的缺点,研制了一种固液分离过滤-吸附富集联动装置.该装置主要由粗过滤器、离心分离屏、倒置微孔过滤器、固相吸附柱、流速控制阀和真空泵组成.与传统的滤膜过滤方式相比,其过滤效率提高了约1.5...