测定地表水细菌总数存在的问题分析

通过对涪陵区环境保护监测站1997年～2001年长江、乌江涪陵段不同水期水质例行监测结果进行统计分析,得出了测定地表水细菌总数存在的问题,阐明了解决的办法。     

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.     

Influence of geology on arsenic concentrations in ground and surface water in central Lesvos, Greece

The occurrence of As was studied in groundwater used for human consumption and irrigation, in stream water and sediments and in water from thermal springs in the drainage basin of Kalloni Gulf, island of Lesvos, Greece, in order to investigate the potential influence of the geothermal field of Polichnitos-Lisvori on the ground and surface water systems of the area. Total dissolved As varied in the range <0.7-88.3 microg L(-1) in groundwater, 41.1-90.7 microg L(-1) in thermal spring water and 0.4-13.2 microg L(-1) in stream water, whereas As concentrations in stream sediments varied between 2.0-21.9 mg kg(-1). Four out of 31 groundwater samples exceeded the EC standard of 10 microg L(-1). The survey revealed an enrichment in both surface and groundwater hydrological systems in the northern part of the area (average concentrations of As in groundwater, stream water and stream sediment: 8.0 microg L(-1), 8.8 microg L(-1) and 15.0 mg kg(-1) respectively), in association with the volcanic bedrocks, while lower As concentrations were found in the eastern part (average concentrations in groundwater, stream water and stream sediment: 2.9 microg L(-1), 1.7 microg L(-1) and 5.9 mg kg(-1) respectively), which is dominated by ophiolitic ultramafic formations. The variation of As levels between the different parts of the study area suggests that local geology exerts a determinant influence on As geochemical behaviour. On the other hand, the geothermal activity manifested in the area of Polichnitos-Lisvori does not affect the presence of As in groundwater and streams.     

Monitoring dissolved organic carbon in surface and drinking waters

The presence of natural organic matter (NOM) strongly impacts drinking water treatment, water quality, and water behavior during distribution. Dissolved organic carbon (DOC) concentrations were determined daily over a 22 month period in river water before and after conventional drinking water treatment using an on-line total organic carbon (TOC) analyzer. Quantitative and qualitative variations in organic matter were related to precipitation and runoff, seasons and operating conditions. Following a rainfall event, DOC levels could increase by 3.5 fold over baseflow concentrations, while color, UV absorbance values and turbidity increased by a factor of 8, 12 and 300, respectively. Treated water DOC levels were closely related to the source water quality, with an average organic matter removal of 42% after treatment.     

Multi-criteria decision analysis with probabilistic risk assessment for the management of contaminated ground water

Traditionally, environmental decision analysis in subsurface contamination scenarios is performed using cost–benefit analysis. In this paper, we discuss some of the limitations associated with cost–benefit analysis, especially its definition of risk, its definition of cost of risk, and its poor ability to communicate risk-related information. This paper presents an integrated approach for management of contaminated ground water resources using health risk assessment and economic analysis through a multi-criteria decision analysis framework. The methodology introduces several important concepts and definitions in decision analysis related to subsurface contamination. These are the trade-off between population risk and individual risk, the trade-off between the residual risk and the cost of risk reduction, and cost-effectiveness as a justification for remediation. The proposed decision analysis framework integrates probabilistic health risk assessment into a comprehensive, yet simple, cost-based multi-criteria decision analysis framework. The methodology focuses on developing decision criteria that provide insight into the common questions of the decision-maker that involve a number of remedial alternatives. The paper then explores three potential approaches for alternative ranking, a structured explicit decision analysis, a heuristic approach of importance of the order of criteria, and a fuzzy logic approach based on fuzzy dominance and similarity analysis. Using formal alternative ranking procedures, the methodology seeks to present a structured decision analysis framework that can be applied consistently across many different and complex remediation settings. A simple numerical example is presented to demonstrate the proposed methodology. The results showed the importance of using an integrated approach for decision-making considering both costs and risks. Future work should focus on the application of the methodology to a variety of complex field conditions to better evaluate the proposed methodology.     

Assessment of dry season surface, ground, and treated water quality in the Cape Coast municipality of Ghana

This aim of this monitoring was to assess water quality in a dry season for the Cape Coast municipality in Ghana, which has been experiencing chronic water shortages. Fifteen different sampling stations—four surface, five ground, and six tap water samples—were analyzed for physicochemical and microbiological parameters during January to April 2005. Levels or trends in water quality that may be deleterious to sensitive water uses, including drinking, irrigation, and livestock watering have been noted with reference to well-established guidelines. Exceedances to some health-based drinking water guidelines included positive coliform for various water samples; pH for all groundwater samples (pH 5.9 ± 0.3); conductivity for 50% groundwater; color for about a third of groundwater and tap water; Mn for 44% tap water, 67% groundwater, and 50% surface water samples. The World Health Organization laundry staining Fe guideline of 0.3 mg/l was exceeded by 75% of surface water, 44% tap water, and 53% groundwater samples. The corresponding Mn guideline of 0.1 mg/l was exceeded by all the water samples. Respectively, all surface water samples and also 75% of the surface water exceeded some known Cu and Zn guideline for the protection of aquatic life. Compared to some historic data for Fosu Lagoon, the current study shows a lowering of ~1 pH unit, increase of ~65% $\text{NH}_{3}$ , one to two orders of magnitude increase in PO $_{4}^{{3}^{-}}$ , and more than two orders of magnitude increase in NO $_{3}^{-}$ . In several instances, tap water samples collected at the consumers’ end of the distribution system did not reflect on the true quality of the treated water. Mn, SO $_{4}^{{2}^{-}}$ , PO $_{4}^{{3}^{-}}$ , Cu, and Zn were among the chemical contaminations observed to occur in the distribution system.     

The dynamics of dissolved oxygen concentration for water quality monitoring and assessment in polder ditches

This study deals with the use of the dynamics of dissolved oxygen concentration for water quality assessment in polder ditches. The dynamics of the dissolved oxygen concentration, i.e. the temporal and spatial variations in a few polder ditches under a range of natural, pollution and management conditions is presented. Five requisites formulated for the water quality indicator are discussed: (1) its relation with water quality goals, (2) nature and amount of information it provides, (3) if it could be standardized, (4) if it could be manipulated and (5) its measurability.     

Detection of seasonal variations in surface water quality using discriminant analysis

In the study, discriminant analysis (DA) was applied to water quality data set monitored in winter and summer months along 3 years to investigate seasonal variations of Tahtali Reservoir water quality. The variables were divided into two categories as “parameters naturally found in surface waters—Al, Fe, Mn, F, Ba, Cl, and SO₄” and “pollutants—biochemical oxygen demand, chemical oxygen demand, and NO₃”. Linear discriminant functions were calculated to distinguish between winter and summer samples. Results revealed that water quality variables (naturally found in surface water and also pollutants) were distinctly different between two seasons. Seasonal changes of water quality caused by anthropogenic activities should be taken into consideration by the water managers especially in summer seasons in which higher concentrations were observed. The study showed that DA can be applied successfully to establish the seasonal variation in surface water quality and make it possible to design a future temporal sampling strategy in an optimal manner.     

Application of water quality indices and analysis of the surface water quality monitoring network in semiarid North-Central Chile

Surface water quality has increasing importance worldwide and is particularly relevant in the semiarid North-Central Chile, where agriculture and mining activities are imposing heavy pressure on limited water resources. The current study presents the application of a water quality index in four watersheds of the 29°-33°S realm for the period 1999-2008, based on the Canadian Council of Ministers for the Environment approach and the Chilean regulation for irrigation water quality. In addition, two modifications to the index are tested and a comprehensive characterization of the existing monitoring network is performed through cluster analysis. The basins studied show fairly good water quality in the overall, specially the Limarí basin. On the other hand, the lower index values were obtained for the headwaters of Elqui, associated with the El Indio mining district. The first modification of the indicator (i.e., to consider parameters differentially according to their effect on human health or the environment) did not produce major differences with respect to the original index, given the generally good water quality. The second modification (i.e., to consider as threshold values the more restrictive figures derived from a set of regulations) yielded important differences in the indicator values. Finally, an adequate characterization of the monitoring network was obtained. The results presented spatial coherence and the information can be used as a basis for the optimization of the monitoring network if required.     

Water quality analysis of surface water: a Web approach

The chemical, physical and biological characteristics of water with respect to its suitability describe its quality. Concentration of pesticides or fertilisers degrades the water quality and affects marine life. A comprehensive environmental data information system helps to perform and complete common tasks in less time with less effort for data verification, data calculations, graph generation, and proper monitoring, which helps in the further mitigation step. In this paper, focus is given to a web-based system developed to express the quality of water in the imprecise environment of monitoring data. Water samples were analyzed for eight different surface water parameters, in which four parameters such as pH, dissolved oxygen, biochemical oxygen demand, and fecal coliform were used for the water quality index calculation following MPCB Water Quality Standards of class A-II for best designated use. The analysis showed that river points in a particular year were in very bad category with certainty level of 0–38 % which is unsuitable for drinking purposes; samples in bad category had certainty level that ranged from 38 to 50 %; samples in medium to good category had certainty levels from 50 to 100 %, and the remaining samples were in good to excellent category, suitable for drinking purposes, with certainty levels from 63 to 100 %.     

Evaluating response surface designs for uncertainty analysis and prescriptive applications of a large-scale water quality model

Environmental models are often too large and cumbersome for effective use in regulatory decision making or in the characterization of uncertainty. This paper describes and compares four response surfaces that could complement a large-scale water quality model, the U.S. National Water Pollution Control Assessment Model (NWPCAM), in simulation and regulatory decision support applications. Results show that a physically based reduced-form model that exploits the mathematical structure of the underlying water quality model is a better predictor of policy-relevant outputs than the polynomial expansions that are frequently used in response surface studies.     

Sampling and analysis considerations for the determination of hexavalent chromium in workplace air

Airborne hexavalent chromium (Cr[VI]) is a known human respiratory carcinogen and allergen. Workers in a variety of industries may be exposed to airborne hexavalent chromium, with exposures frequently occurring via inhalation and/or dermal contact. Analytical methods for the measurement of Cr(VI) compounds in workplace samples, rather than for the determination of total elemental chromium in workplace air, are often desired because exposure limit values for Cr(VI) compounds are much lower than for total Cr. For years, sampling and analytical test methods for airborne Cr(VI) have been investigated so as to provide means for occupational exposure assessment to this highly toxic species. Inter-conversion of trivalent chromium (Cr[III]) and Cr(VI) can sometimes occur during sampling and sample preparation, and efforts to minimize unwanted redox reactions involving these chromium valences have been sought. Because of differences in toxicity, there is also interest in the ability to differentiate between water-soluble and insoluble forms of Cr(VI), and procedures that provide solubility information concerning Cr(VI) compounds have been developed. This paper reviews the state of the art concerning the measurement of airborne Cr(VI) compounds in workplace aerosols and related samples.     

Sampling procedure for the foliar analysis of deciduous trees

Sampling can be the source of the greatest errors in the overall results of foliar analysis. This paper reviews the variability in heavy metal concentrations in tree crowns, which is a feature that should be known and understood when designing a suitable leaf sampling procedure. The leaf sampling procedures applied in 75 articles were examined. Most of the environmental studies used a closely related form of the UN/ECE-EC leaf sampling procedure, which was developed for the long-term monitoring of forest condition. Studies with objectives outside the UN/ECE-EC field of application should utilize a sampling procedure that is in accordance with the objectives of the study and based on the observed variation in pilot and similar studies. The inherent sources of heavy metal variability inside the stand, i.e. the crown class, stand management, site properties, crown dimensions, infections, seasons, etc. were discussed, but the underlying causes of this variability are rarely understood. The inherent variability in tree crowns is the reason for using leaf sampling as a tool in pollution studies. The objectives of a pollution study determine which sources of variability are utilized by the researcher.     

Organochlorine insecticide residues in drinking and ground water in and around Delhi

A multiresidue method was developed for the estimation of 15organochlorine pesticides in water. 50 samples of drinking watersupplied by the Municipal Corporation to the residential areasof Delhi and 20 ground water samples from nearby villages usedfor irrigation were monitored for the presence of organochlorineinsecticides by the method developed. Although, organochlorinepesticides were detected in the ground water and irrigationwater samples, the levels of pesticides were below the MaximumContaminant Level as prescribed by WHO. No organochlorineinsecticides were detected in any of the drinking water samples.     

Major and trace element partitioning between dissolved and particulate phases in Antarctic surface snow

In order to provide a new insight into the Antarctic snow chemistry, partitioning of major and trace elements between dissolved and particulate (i.e. insoluble particles, >0.45 μm) phases have been investigated in a number of coastal and inland snow samples, along with their total and acid-dissolvable (0.5% nitric acid) concentrations. Alkaline and alkaline-earth elements (Na, K, Ca, Mg, Sr) were mainly present in the dissolved phase, while Fe and Al were predominantly associated with the particulate matter, without any significant difference between inland and coastal samples. On the other hand, partitioning of trace elements depended on the sampling site position, showing a general decrease of the particulate fraction by moving from the coast to the plateau. Cd, Cu, Pb and Zn were for the most part in the dissolved phase, while Cr was mainly associated with the particulate fraction. Co, Mn and V were equally distributed between dissolved and particulate phases in the samples collected from the plateau and preferentially associated with the particulate in the coastal samples. The correlation between the elements and the inter-sample variability of their concentration significantly decreased for the plateau samples compared to the coastal ones, according to a change in the relative contribution of the metal sources and in good agreement with the estimated marine and crustal enrichment factors. In addition, samples from the plateau were characterised by higher enrichment factors of anthropogenic elements (Cd, Cr, Cu, Pb and Zn), compared to the coastal area. Finally, it was observed that the acid-dissolvable metal concentrations were generally lower than the total concentration values, showing that the acid treatment can dissolve only a given fraction of the metal associated with the particulate (<20% for iron and aluminium).     

Application of QUAL2Kw for water quality modeling and dissolved oxygen control in the river Bagmati

A stream water quality model, QUAL2Kw, was calibrated and validated for the river Bagmati of Nepal. The model represented the field data quite well with some exceptions. The influences of various water quality management strategies have on DO concentrations were examined considering: (i) pollution loads modification; (ii) flow augmentation; (iii) local oxygenation. The study showed the local oxygenation is effective in raising DO levels. The combination of wastewater modification, flow augmentation and local oxygenation is necessary to ensure minimum DO concentrations. This reasonable modeling guarantees the use of QUAL2Kw for future river water quality policy options.     

A method for monitoring ground water quality near waste storage facilities

A practical optimization approach developed in this paper derives effective monitoring configurations for detecting contaminants in ground water. The approach integrates numerical simulation of contaminant transport and mathematical programming. Well sites identified by the methodology can be monitored to establish the occurrence of a contaminant release before a plume migrates to a regulatory compliance boundary. Monitoring sites are established along several horizons located between the downgradient margin of a contaminant source and a compliance boundary. A horizon can form an effective line of defense against contaminant migration to the compliance boundary if it is spanned (covered) by a sufficient number of sites to yield a well spacing that is equal to or less than a maximum value established by numerical modeling. The objective function of the integer programming model formulation expresses the goals of: (1) covering a maximum number of siting horizons, and (2) allocating wells to the single most effective horizon. The latter is determined from well spacing requirements and the width of the zone of potential contaminant migration traversed by the horizon. The methodology employs a highly tractable linear programming model formulation, and the user is not required to predefine a set of potential well sites. These attributes can facilitate its implementation in practice.     

Application of cryofocusing hydride generation and atomic fluorescence detection for dissolved mercury species determination in natural water samples

The concentration levels of mercury (Hg) species in natural water samples are usually low. Consequently, accurate analysis with low detection limits is still a major problem. In this work, a method was applied for the simultaneous direct determination of dissolved mercury species in water samples by on-line hydride generation (HG), cryogenic trapping (CT), gas chromatography (GC) and detection by atomic fluorescence spectrometry (AFS). The suitability of the method for real samples with different organic matter and chloride contents was evaluated by recovery experiments in synthetic and natural spiked water samples. The HG method was compared with other current available methods for mercury analysis with respect to the different fraction of mercury analysed, i.e. 'reactive', 'reducible' or total. HG derivatization and SnCl2 reduction (with and without previous oxidation with BrCl) were applied to synthetic and natural (spiked and non-spiked) water samples. The influence of chloride and dissolved organic matter concentrations was studied. The results suggest that the HG procedure is suitable for the simultaneous determination of Hg2+ and MeHg+ in surface water samples. Inorganic mercury analysed by HG (i.e. reducible) is close to the total inorganic mercury.     

Comparison of dissolved organic matter fractions in a secondary effluent and a natural water

This research compared the structural and chemical characteristics among dissolved organic matter (DOM) fractions within the same source and among different origins. Samples taken from the Taiping Wastewater Treatment Plant (TWTP) (Harbin, China) and from the Songhuajing River (SR), Heilongjiang Province, China were chosen to represent waters containing DOM of wastewater origin and of natural-water origin, respectively. DOM was fractionated using XAD resins into five fractions: hydrophobic acid (HPO-A), hydrophobic neutral (HPO-N), transphilic acid (TPI-A), transphilic neutral (TPI-N) and hydrophilic fraction (HPI). The SR fractions were more UV-sensitive and more reactive with chlorine in formation of trihalomethanes (THMs) than the TWTP secondary effluent (TSE) fractions. The aromatic character peaks in the Fourier-transform infrared (FT-IR) spectra of SR fractions were clearer than those of TSE fractions. On the other hand, the peaks of carbohydrates in TSE fractions were more prominent in comparison with SR fractions. In addition, the amide-2 peak was present in the spectra of all the five TSE fractions but not visible in the spectra of SR fractions. The fluorescence results showed that SR DOM fractions contained more fulvic acid-like fluorescent compounds while TSE DOM fractions had higher amounts of protein-like fluorescent components.     

Preliminary assessment of total dissolved trace metal concentrations in Sava River water

This study provides the preliminary data set for total dissolved trace metal concentrations in the surface water of the Sava River in Croatia and the assessment of Sava River water quality status. The highest levels of total dissolved metals were observed for Fe, Mn, and Zn (12.6 +/- 7.8 mirog L(-1), 3.44 +/- 3.95 mirog L(-1), and 2.27 +/- 1.53 mirog L(-1), respectively), the intermediate concentrations for Ni, Cu, and Cr (0.59 +/- 0.14 mirog L(-1), 0.54 +/- 0.14 mirog L(-1), and 0.32 +/- 0.06 mirog L(-1), respectively), and the lowest levels for Co, Pb, and Cd (0.064 +/- 0.022 mirog L(-1), 0.055 +/- 0.051 mirog L(-1), and 0.011 +/- 0.004 mirog L(-1), respectively). The results refer to the grab water samples taken at five sites in the period from March to June, 2006. For four trace metals (Mn, Pb, Zn, and Fe), the high temporal variability within one season was observed. It can present a problem for reliable evaluation of total dissolved concentrations of these metals in the river water, if the assessment is based on the occasional grab water sampling. The comparison of results obtained in this study with previously reported data for several unpolluted rivers indicated that Sava River water reflects a certain anthropogenic impact. However, according to the levels proposed by European regulations, it still can be classified as water containing total dissolved trace metals in concentrations not significantly above the natural level.