Lipophilic organic contaminants in the Rhine river, Germany

Detailed gas chromatographic-mass spectrometric analyses applied to eight Rhine river water samples constituted a comprehensive characterization of the low molecular weight organic contamination. Within the group of predominant anthropogenic contaminants, only a few compounds were characterized as frequently detected or priority pollutants. Numerous compounds exhibiting physiological or ecotoxicological properties are only rarely reported or still unnoticed riverine contaminants. Information on environmental behaviour or ecotoxicological effects is still limited for most of these substances. In particular, several brominated compounds (mono- and dibrominated (methoxyphenyl)propionic acids and hydroxymethylacetophenones) were identified for the first time as environmental contaminants. Quantitative analyses differentiated five groups of pollutants with respect to their concentration profiles. The spatial distribution and the intensity of emission sources on the one hand and the environmental stability as well as the tendency to adsorb on the particulate matter on the other hand determined the quantitative occurrence of individual compounds.     

Toxicological and chemical characterization of organic micropollutants in river po waters (Italy)

River Po waters were collected at the end of the drainage basin, extracted by means of XAD-2 resins and tested for toxicity on aquatic organisms (Daphnia magna and Selenastrum capricornutum) and for mutagenicity with a modified Ames test. The extracts were analyzed by HRGC/FID and selective detectors for the determination of the most common classes of toxic compounds. The relationships between toxicological responses and analytical results are discussed.     

Study of river pollution caused by micropollutants

Of the polluting substances present in surface waters greatest importance is attributed to the micropollutants. Concerning the water quality of the Danube river, among the micropollutants, special attention should be devoted to the petroleum and phenol derivatives, further to some heavy metals (mercury, zinc, etc.). Phenolic compounds in the low concentrations encountered are readily soluble in water, so that they are present in small quantities only in the suspended solids and in the bottom sediment. Petroleum derivatives and fats are of great importance in this respect together with some heavy metals, which tend to adsorb to the suspended solids, respectively to form precipitates and thus to settle to the bottom.The investigations on quality variations were carried out over a Danube section upstream of Budapest. This section offers a model opportunity for studying changes in the pollutants tending to separate and form precipitates in water, the settling thereof as a function of flow conditions and time, etc.These investigations have offered an explanation for the “disappearance” of the persistent substances, which has been observed during the regular water analyses. The results of analyses performed on the water as well as on the bottom sediment are discussed in the paper.     

Modelling the fate of organic micropollutants in stormwater ponds

Urban water managers need to estimate the potential removal of organic micropollutants (MP) in stormwater treatment systems to support MP pollution control strategies. This study documents how the potential removal of organic MP in stormwater treatment systems can be quantified by using multimedia models. The fate of four different MP in a stormwater retention pond was simulated by applying two steady-state multimedia fate models (EPI Suite and SimpleBox) commonly applied in chemical risk assessment and a dynamic multimedia fate model (Stormwater Treatment Unit Model for Micro Pollutants — STUMP). The four simulated organic stormwater MP (iodopropynyl butylcarbamate — IPBC, benzene, glyphosate and pyrene) were selected according to their different urban sources and environmental fate. This ensures that the results can be extended to other relevant stormwater pollutants. All three models use substance inherent properties to calculate MP fate but differ in their ability to represent the small physical scale and high temporal variability of stormwater treatment systems. Therefore the three models generate different results. A Global Sensitivity Analysis (GSA) highlighted that settling/resuspension of particulate matter was the most sensitive process for the dynamic model. The uncertainty of the estimated MP fluxes can be reduced by calibrating the dynamic model against total suspended solids data. This reduction in uncertainty was more significant for the substances with strong tendency to sorb, i.e. glyphosate and pyrene and less significant for substances with a smaller tendency to sorb, i.e. IPBC and benzene. The results provide support to the elaboration of MP pollution control strategies by limiting the need for extensive and complex monitoring campaigns targeting the wide range of specific organic MP found in stormwater runoff.     

Biological processes and organic micropollutants in treatment processes

This paper characterizes the factors that control biodegradation of organic micropollutants in biologically active drinking water processes. Particularly important are the dominance of attached microorganisms, the aerobic potential, the low concentration of organic matter, the very low concentrations of specific micropollutants, and the presence of inorganic electron donors. Biodegradation of the specific compounds is feasible if sufficient microbial growth occurs through utilization of natural organic material and if the secondary-utilization kinetics of the micropollutants are sufficiently rapid.     

Removal of organic micropollutants by coagulation and adsorption

The factors which affect removal of organic micropollutants by coagulation, sedimentation, filtration and activated carbon adsorption will be reviewed. Removal of specific compounds by coagulation, sedimentation and filtration is often slight, unless the pollutants adsorb on particles or associate with humic substances which are then coagulated. By comparison, removal of humic substances by these processes can be substantial, depending upon the water chemistry and the process conditions. Activated carbon may be applied in both the powdered (PAC) and granular (GAC) form. PAC and GAC have been used successfully throughout the world to remove odorous compounds. PAC has been used to a much smaller extent for removal of other micropollutants, but there is much potential for improvement of the application procedure so that good results can be achieved. GAC is widely used to remove micropollutants other than odor in Europe but has not been extensively used for this purpose in North America. The compounds which can be removed by GAC are presented and process monitoring procedures are discussed. Factors which limit its use include incomplete knowledge about which compounds must be removed and what effluent concentrations are acceptable.     

Epidemiologic studies of organic micropollutants in drinking water

Epidemiologic studies have been conducted in order to make a quantitative statement about associations between drinking water contaminants and disease. The basic measures of the association are a rate ratio or relative risk and rate difference or attributable risk. The appropriateness of this measure is dependent on components of study design, data collection, and the analysis of epidemiologic data, and these must be evaluated for each study to determine precision (lack of random error) and validity (lack of systematic error). Internal validity includes considerations for preventing selection bias, minimizing observation bias, and assessing, preventing, and controlling confounding bias within a particular study. No single epidemiologic study is likely to provide a definitive answer, and the results of epidemiologic studies must be interpreted in the context of other scientific information. Epidemiologic studies of organic micropollutants in drinking water have been reviewed and are summarized based on these considerations.     

Cytogenetic changes in fish exposed to water of the river Rhine

The induction of chromosome aberrations in fishes, exposed to Rhinewater, was investigated. The mudminnow, Umbra pygmaea, was chosen for this study, because of its ideal karyotype of 22 large chromosomes. Gill cells were used for chromosome studies.Fish, kept in Rhinewater for 11 days had chromosome breaks in approximately 30% of the metaphases studied. Control fish, exposed to a very good quality of untreated groundwater had breaks in about 8% of the metaphases.Several Rhinewater extracts were tested for their mutagenic potential in the Salmonella-microsome test. The fraction of aromatic compounds was found to be positive. This may indicate that one or more of the compounds present in this fraction were also responsible for the cytogenetic changes found in the fish.     

Modeling equilibrium adsorption of organic micropollutants onto activated carbon

Solute hydrophobicity, polarizability, aromaticity and the presence of H-bond donor/acceptor groups have been identified as important solute properties that affect the adsorption on activated carbon. However, the adsorption mechanisms related to these properties occur in parallel, and their respective dominance depends on the solute properties as well as carbon characteristics. In this paper, a model based on multivariate linear regression is described that was developed to predict equilibrium carbon loading on a specific activated carbon (F400) for solutes reflecting a wide range of solute properties. In order to improve prediction accuracy, groups (bins) of solutes with similar solute properties were defined and solute removals were predicted for each bin separately. With these individual linear models, coefficients of determination (R²) values ranging from 0.61 to 0.84 were obtained. With the mechanistic approach used in developing this predictive model, a strong relation with adsorption mechanisms is established, improving the interpretation and, ultimately, acceptance of the model.     

The occurrence of organic chemicals in the atmosphere of The Netherlands

In this paper concentration levels of various classes of organic chemicals in The Netherlands are reported for the base year 1980. From these levels the average intake of the Dutch population by inhalation was calculated to be approximately 1.5 g year-1. This gives reason for concern because many of the compounds either seem to exhibit carcinogenic properties or are suspected human carcinogens. Apart from (photo)chemical reactions, dry deposition seems to be an important way by which these chemicals are removed from the atmosphere. Although the deposition velocity of many organic chemicals is not well established or is completely unknown we have estimated the yearly deposition in The Netherlands to be approximately 89 000 t.     

Time series analysis on ammonia concentration and load values of the river Rhine

The autocorrelation technique is applied to ammonia data observed in the river Rhine and is used for two purposes. On one hand the error in the determination of the NH₄⁺-concentration, caused by both analysing and sampling errors, can be quantified. On the other hand the behaviour of the NH₄⁺-concentration and NH₄⁺-load is described. It is indicated that the NH₄⁺-load is a stochastic variable containing a periodicity, whereas the NH₄⁺-concentration is a merely stochastic variable with a large time constant.     

Effects of activated carbon characteristics on the simultaneous adsorption of aqueous organic micropollutants and natural organic matter

The overall objective of this research was to determine the effects of physical and chemical activated carbon characteristics on the simultaneous adsorption of trace organic contaminants and natural organic matter (NOM). A matrix of 12 activated carbon fibers (ACFs) with three activation levels and four surface chemistry levels (acid-washed, oxidized, hydrogen-treated, and ammonia-treated) was studied to systematically evaluate pore structure and surface chemistry phenomena. Also, three commercially available granular activated carbons (GACs) were tested. The relatively hydrophilic fuel additive methyl tertiary-butyl ether (MTBE) and the relatively hydrophobic solvent trichloroethene (TCE) served as micropollutant probes. A comparison of adsorption isotherm data collected in the presence and absence of NOM showed that percent reductions of single-solute TCE and MTBE adsorption capacities that resulted from the presence of co-adsorbing NOM were not strongly affected by the chemical characteristics of activated carbons. However, hydrophobic carbons were more effective adsorbents for both TCE and MTBE than hydrophilic carbons because enhanced water adsorption on the latter interfered with the adsorption of micropollutants from solutions containing NOM. With respect to pore structure, activated carbons should exhibit a large volume of micropores with widths that are about 1.5 times the kinetic diameter of the target adsorbate. Furthermore, an effective adsorbent should possess a micropore size distribution that extends to widths that are approximately twice the kinetic diameter of the target adsorbate to prevent pore blockage/constriction as a result of NOM adsorption.     

Geochemistry of suspended particulate matter in two natural sedimentation basins of the river Rhine

Multivariate analysis procedures have been used to trace possible correlations between changes in the composition of particulate organics and changes in the ratios of trace metal contents of suspended matter present in two major sedimentation basins of the river Rhine. In both basins, seaward gradients are observed in the organic characteristics as well as in the trace metal “patterns”. These two phenomena are well correlated. For both basins the changes in the two types of characteristics can be explained by simultaneously operating processes of sedimentation, autochthonous production and sediment resuspension.     

Glutathione s-transferase in aquatic macro-invertebrates and its interaction with different organic micropollutants

In higher organisms, glutathione S-transferase (GST) plays a key role in the detoxification of a large number of xenobiotics. In the present work the presence of GST in aquatic macro-invertebrates and its possible significance as a detoxification mechanism of organic micropollutants in the aquatic environment is investigated. So far, GST has been found in 20 macro-invertebrates (in adults as well as in larvae) and in insects as well as in other animal groups. The GST activities were relatively high, ranging from 10 to 600% of the activity found in rat liver. The interaction of quinones, o-chloranil and chlorophenoxyalkyl acids with the GST activity, in extracts from three different macro-invertebrates, revealed an inhibition which was quite similar to that previously found for rat liver GST. In Tubifex tubifex extracts at least three different GST isoenzymes could be demonstrated. These partially purified isoenzymes were used for the kinetic analysis of GST inhibition by 2,4-dichlorophenoxyalkyl acid and 1,4-benzoquinone, using Lineweaver—Burk plots. The same kinetic patterns were observed as for rat liver GST. The results demonstrate that the interactions of the compounds investigated with aquatic macro-invertebrate and with rat liver GST are in very good agreement. It is concluded that macro-invertebrate GST can play a key role in the detoxification of organic micro-pollutants in the aquatic environment.     

Natural versus wastewater derived dissolved organic carbon: implications for the environmental fate of organic micropollutants

The interaction of organic micropollutants with dissolved organic carbon (DOC) can influence their transport, degradation and bioavailability. While this has been well established for natural organic carbon, very little is known regarding the influence of DOC on the fate of micropollutants during wastewater treatment and water recycling. Dissolved organic carbon-water partition coefficients (K_DOC) for wastewater derived and reference DOC were measured for a range of micropollutants using a depletion method with polydimethylsiloxane disks. For micropollutants with an octanol-water partition coefficient (log K_OW) greater than 4 there was a significant difference in K_DOC between reference and wastewater derived DOC, with partitioning to wastewater derived DOC over 1000 times lower for the most hydrophobic micropollutants. The interaction of nonylphenol with wastewater derived DOC from different stages of a wastewater and advanced water treatment train was studied, but little difference in K_DOC was observed. Organic carbon characterisation revealed that reference and wastewater derived DOC had very different properties due to their different origins. Consequently, the reduced sorption capacity of wastewater derived DOC may be related to their microbial origin which led to reduced aromaticity and lower molecular weight. This study suggests that for hydrophobic micropollutants (log K_OW > 4) a higher concentration of freely dissolved and thus bioavailable micropollutants is expected in the presence of wastewater derived DOC than predicted using K_DOC values quantified using reference DOC. The implication is that naturally derived DOC may not be an appropriate surrogate for wastewater derived DOC as a matrix for assessing the fate of micropollutants in engineered systems.     

The occurrence and role of Bdellovibrio bacteriovorus in a polluted river

Bdellovibrio bacteriovorus was found to occur in a polluted river in numbers averaging, over an 18 month period, 10–100 parasites/ml. The parasite was not able to grow at river temperatures on host concentrations below about 10⁶–10⁷ bacteria per ml and even at these had a doubling time of only 24–48 h. The results have indicated that the parasite was not important in reducing the bacterial population of the river studied.     

Mercury in the river mersey, its estuary and tributaries during 1973 and 1974

Mercury levels found in waters and suspended matter from 53 stations, occupied four times at 3-monthly intervals, showed that most mercury was associated with particulates but the amount varied during the year. In the polluted region between Warrington and Runcorn, where fresh-water and sea-water converge, >80% of the mercury was associated with the particulates. Dissolved mercury concentrations and the mercury load on particulate matter were always greater in freshwater than in tidal waters, except during a flood. A model of partitioning of mercury between particulate and dissolved phases is presented. The River Weaver and the Manchester Ship Canal were grossly polluted with mercury throughout that year due to a Castner-Kelner plant at Runcorn. Dredge spoils and water flow transport 17 (range 8–138) and 1.55 ± 65% tonnes yr⁻¹ respectively of mercury into Liverpool Bay.     

Pore distribution effect of activated carbon in adsorbing organic micropollutants from natural water

Adsorption isotherms of organic micropollutants in coexistence with natural organic matter (NOM) were analyzed to evaluate the impacts of pore size distribution of activated carbon (AC) on the competition effects of the NOM. Single solute adsorption experiments and simultaneous adsorption experiments with NOM contained in a coagulation-pretreated surface water were performed for four agricultural chemicals and three coal-based activated carbons (ACs) having different pore distributions. The results showed that, for all the carbons used, the adsorption capacity of the chemicals was reduced distinctly in the presence of NOM. Such a reduction was more apparent for AC with a larger portion of small pores suitable for the adsorption of small organic molecules and for the agricultural chemicals with a more hydrophilic nature. Ideal adsorbed solution theory (IAST) incorporated with the Freundlich isotherm expression (IAST-Freundlich model) could not interpret the impact of NOM on the adsorption capacity of the chemicals unless a pore blockage effect caused by the adsorption of NOM was also considered. By taking into account this effect, the adsorption isotherm of the chemicals in the presence of NOM was well described, and the capacity reduction caused by the NOM was quantitatively assessed from the viewpoints of the site competition and the pore blockage. Analytical results clearly indicated that pore blockage was an important competition mechanism that contributed to 10-99% of the total capacity reductions of the chemicals, the level depended greatly on the ACs, the chemicals and the equilibrium concentrations, and could possibly be alleviated by broadening the pore size distributions of the ACs to provide a large volume percentage for pores with sizes above 30 A.     

Mechanism underlying the removal of organic micropollutants during flocculation by an aluminum or iron salt

The mechanism underlying the removal of four micropollutants—lindane, benzopyrene, diethylphtalate and dibutylphtalate—by mineral coagulants, namely, basic aluminum polychloride and ferric chloride was investigated. In each case an adsorption mechanism of the micropollutants on the gels of aluminum and iron hydroxyde has been revealed. For the first two micropollutants, the isotherms obey Henry's law. For the others, absorption is due to a first order phase change in the adsorbed layer due to the influence of lateral bonds.     

Sources and transport of selected organic micropollutants in urban groundwater underlying the city of Halle (Saale), Germany

In this study, we used isotopic (delta18O, delta2H, delta34S-SO4) and chemical tracers (boron) to assess the sources and transport processes of the micropollutants carbamazepine, galaxolide, and bisphenol A in groundwater underlying the city of Halle (Saale), Germany. Their ubiquitous presence in urban groundwater results from a combination of local river water infiltration, sewer exfiltration, and urban stormwater recharge. Attenuation during transport with infiltrating river water increased from carbamazepine (0-60%) to galaxolide (60-80%) in accordance with their increasing sorption affinity and decreasing recalcitrance against biodegradation. Distinctly higher attenuation during transport was found for carbamazepine (85-100%) and galaxolide (95-100%) if micropollutants originated from sewer exfiltration. Most likely, this is related to higher contents of organic matter and higher transit times of the respective flow paths. Although attenuation undoubtedly also affects the transport of bisphenol A, quantification is limited due to additional contributions from the urban stormwater recharge. As a consequence, micropollutant loads in groundwater indicate that groundwater discharge may dominate the export of bisphenol A from urban areas.