Influence of dissolved organic carbon on toxicity of copper to a unionid mussel (Villosa iris) and a cladoceran (Ceriodaphnia dubia) in acute and chronic water exposures

Acute and chronic toxicity of copper (Cu) to a unionid mussel (Villosa iris) and a cladoceran (Ceriodaphnia dubia) were determined in water exposures at four concentrations of dissolved organic carbon (DOC; nominally 0.5, 2.5, 5, and 10 mg/L as carbon [C]). Test waters with DOC concentrations of 2.5 to 10 mg?C/L were prepared by mixing a concentrate of natural organic matter (Suwannee River, GA, USA) in diluted well water (hardness 100 mg/L as CaCO(3) , pH 8.3, DOC 0.5 mg C/L). Acute median effect concentrations (EC50s) for dissolved Cu increased approximately fivefold (15-72 μg Cu/L) for mussel survival in 4-d exposures and increased about 11-fold (25-267 μg Cu/L) for cladoceran survival in 2-d exposures across DOC concentrations from 0.5 to 10 mg?C/L. Similarly, chronic 20% effect concentrations (EC20s) for the mussel in 28-d exposures increased about fivefold (13-61 μg Cu/L for survival; 8.8-38 μg Cu/L for biomass), and the EC20s for the cladoceran in 7-d exposures increased approximately 17-fold (13-215 μg Cu/L) for survival or approximately fourfold (12-42 μg Cu/L) for reproduction across DOC concentrations from 0.5 to 10 mg?C/L. The acute and chronic values for the mussel were less than or approximately equal to the values for the cladoceran. Predictions from the biotic ligand model (BLM) used to derive the U.S. Environmental Protection Agency's ambient water quality criteria (AWQC) for Cu explained more than 90% of the variation in the acute and chronic endpoints for the two species, with the exception of the EC20 for cladoceran reproduction (only 46% of variation explained). The BLM-normalized acute EC50s and chronic EC20s for the mussel and BLM-normalized chronic EC20s for the cladoceran in waters with DOC concentrations of 2.5 to 10 mg?C/L were equal to or less than the final acute value and final chronic value in the BLM-based AWQC for Cu, respectively, indicating that the Cu AWQC might not adequately protect the mussel from acute and chronic exposure, and the cladoceran from chronic exposure.     

Nitrate removal from drinking water by point of use ion exchange

Background: A laboratory study was conducted to investigate the ability of a special type of strongly basic resin MP500WS for the removal of nitrate from different waters. Methods: Two different types of Point-of-Use (POU) devices containing an identical resin were used. MP500WS known as macro porous was used in POU devices for removal of high concentrations of nitrate and sulfate ions from water. Sulfate and chloride ions are considered the most important interferences in the treatment process of nitrate by most anion exchange resins. Results: The results obtained by treatment of water samples having different ranges of nitrate (20 to150 mg/L), sulfate (50, 100 and 800 mg/L) and chloride (50 and 500 mg/L) have shown that the method was suitable for delivering water with NO(3) concentrations in less than its maximum contaminant level (MCL=45 mg/L) as long as the initial NO(3), SO(4) and Cl concentration has remained in less than 150, 100 and 500 mg/L, respectively. Conclusion: For this purpose, POU systems that utilize a suitable tested resin may be considered as an economical and effective alternative to conventional systems. This study shows this strategy very effective for nitrate reduction to acceptable levels when macro porous type strongly basic resin is used as the resin.     

Characteristics of strains of Acinetobacter spp. after culture in various media

Growth, surface properties, production of lipase, histamine and some signal molecules (N-acyl-homoserine lactones, AHLs) in four Acinetobacter baumannii strains, in one Acinetobacter lwoffii and in one Acinetobacter haemolyticus strain cultivated in three complex media were studied. More intensive growth of bacterial suspensions was observed in Mueller-Hinton broth and in brain heart infusion in comparison with growth in proteose peptone. Greater growth of bacterial strains (with the exception of A. haemolyticus) in these two media was associated with more significant surface hydrophobicity of bacteria manifested by their adherence to xylene. A higher level of lipase was found in all strains (with the exception of A. haemolyticus) after cultivation in Mueller-Hinton broth. Composition of culture medium did not affect production of histamine. None of the studied strains in any medium tested produced short-chained unsubstituted AHLs that can be ones of the signal molecules shared with cell-to-cell communication.     

Fluoride and bacterial content of bottled water vs tap water

CONTEXT: Bottled water has become a status symbol and is frequently used in place of tap water. While both waters are considered safe to drink, is either more beneficial in preventing tooth decay and is there a difference in purity? OBJECTIVE: To determine the fluoride level and bacterial content of commercially bottled waters municipal tap water and to compare the results. DESIGN: Comparative study. SETTING: Cleveland, Ohio. SAMPLE: Fifty-seven samples of 5 categories of bottled waters were purchased from local stores. Samples of tap water were collected in sterile containers from the 4 local water processing plants. Fluoride levels were determined by an ion-selective electrode method. Water was cultured quantitatively and levels of bacteria were calculated as colony-forming units (CFUs) per milliliter. MAIN OUTCOME MEASURE: Fluoride levels and bacterial counts. RESULTS: Fluoride levels within the range recommended for drinking water by the Ohio Environmental Protection Agency, Cincinnati, 0.80 to 1.30 mg/L, were found in only 3 samples of bottled water tested. The fluoride levels of tap water samples were within 0.04 mg/L of the optimal fluoride level of 1.00 mg/L. The bacterial counts in the bottled water samples ranged from less than 0.01 CFU/mL to 4900 CFUs/mL, including 6 samples with levels substantially above 1000 CFUs/mL. In contrast, bacterial counts in samples of tap water ranged from 0.2 to 2.7 CFUs/mL. CONCLUSIONS: Five percent of the bottled water purchased in Cleveland fell within the required fluoride range recommended by the state, compared with 100% of the tap water samples, all of which were also within 0.04 mg/L of the optimal fluoride level of 1.00 mg/L. Use of bottled water based on the assumption of purity can be misguided. Recently, the Environmental Protection Agency, Washington, DC, published a final ruling that requires community water systems to regularly report to the public on the quality of local tap water; there are no similar proposals to determine the quality of bottled water through labeling.     

The effects of low hardness and pH on copper toxicity to Daphnia magna

The majority of metal toxicity data available for freshwater organisms have been generated in laboratory water at pH > 6.5 and hardness > 50 mg/L as CaCO3. Extrapolation of these results to soft surface waters (i.e., hardness < or = 40 mg/L as CaCO3), similar to predominant conditions in the southeastern United States, may prove challenging. For example, South Carolina has surface waters that average 20 mg/L as CaCO3, and exist at extremes of 1 and 600 mg/L as CaCO3. This research characterized the acute toxicity of Cu to Daphnia magna in waters with low hardness and low pH. The 48-h total Cu median lethal concentrations were related to water hardness over a hardness range of 8 to 51 mg/L as CaCO3. Although toxicological differences existed between water hardness of 7 and 20 mg/L as CaCO3 (p = 0.0001), differences in pH (range 5.5-8.5) did not influence acute Cu toxicity. Results of these laboratory studies will provide the data needed to more accurately predict organism response to Cu in waters with low pH and low hardness.     

The effect of calcium and magnesium ratios on the toxicity of copper to five aquatic species in freshwater

While it is generally accepted that water hardness affects copper toxicity, the major ions that contribute to water hardness (calcium [Ca] and magnesium [Mg]) may affect copper toxicity differently. This is important because the Ca:Mg ratio in standard laboratory-reconstituted waters often differs from the ratio in natural surface waters. Copper toxicity was assessed for five different aquatic species: rainbow trout (RBT), fathead minnow (FHM), Ceriodaphnia dubia, Daphnia magna, and an amphipod (Gammarus sp.) under different Ca:Mg ratios (4:0, 3:1, 1:1, 1:3, and 1:4 mass basis) at a common hardness (180 mg/L as CaCO3) and alkalinity (120 mg/L as CaCO3). Copper toxicity increased at lower Ca:Mg ratios for RBT but increased at higher Ca:Mg ratios for D. magna. Fathead minnows (<24 h old) were more sensitive to copper in 1:1 Ca:Mg waters compared to 3:1 Ca:Mg waters. The toxicity of copper did not vary under different Ca:Mg ratios for Gammarus sp., C. dubia, and 28-d-old FHM. The effect of Ca:Mg ratios on copper toxicity changed for D. magna in softer water (90 mg/L as CaCO3) compared with hard water studies.     

Toxicity of Manganese to Ceriodaphnia dubia and Hyalella azteca

Manganese is a toxic element frequently overlooked when assessing toxicity of effluents, sediments, and pore waters. Manganese can be present at toxic levels in anoxic solutions due to increased solubility under chemically reducing conditions, and it can remain at those levels for days in aerated test waters due to slow precipitation kinetics. Ceriodaphnia dubia and Hyalella azteca are freshwater organisms often used for toxicity testing and recommended for assessments of effluents and pore waters. Lethal and reproductive-inhibition concentrations of Mn were determined for C. dubia in acute 48-h tests and chronic three-brood tests using animals <24 h old and between 24 and 48 h old. Sensitivity of H. azteca to Mn was determined with 7-day-old animals in acute 96-h tests. Tests were run at three levels of water hardness to assess the amelioratory effect, which was often significant. Manganese concentrations were measured analytically at test initiation and after 96 h for calculation of toxicity and determination of Mn precipitation during the tests. Minimal amounts of Mn (≤3%) precipitated within 96 h. LC₅₀s determined for H. azteca progressively increased from 3.0 to 8.6 to 13.7 mg Mn/L in soft, moderately hard, and hard waters, respectively. The tolerance of C. dubia to Mn was not significantly different between moderately hard and hard waters, but was significantly lower in soft water. Manganese sensitivity of C. dubia was not significantly different between the ages tested. Acute LC₅₀ values for C. dubia averaged 6.2, 14.5 and 15.2 mg Mn/L and chronic IC₅₀ values averaged 3.9, 8.5 and 11.5 mg Mn/L for soft, moderately-hard and hard waters, respectively. Manganese toxicity should be considered when assessing solutions with concentrations approaching these levels. Received: 21 June 1999/Accepted: 5 October 1999     

Annual Fluctuations of Endocrine-Disrupting Compounds at the Lower End of the Lima River,Portugal, and in Adjacent Coastal Waters

The Lima River is a Spanish–Portuguese water body. Notwithstanding the fact that the river incorporates protected natural areas, levels of endocrine-disrupting compounds (EDCs) within its waters have never been measured; such EDCs include the following: natural and pharmaceutical oestrogens (17β-estradiol, E1, and 17α-ethynylestradiol), industrial and household pollutants (4-octylphenol, 4-nonylphenol, and their monoethoxylates and diethoxylates, and bisphenol A), phytoestrogens (formononetin, biochanin A, daidzein, genistein), and phytosterols (namely, sitosterol). To obtain an understanding of levels of EDCs, water samples were taken from eight sampling sites along the river every 2 months during a 1-year period (2011). The water samples were preconcentrated (Oasis HLB cartridges), cleaned (silica cartridges), and analysed using gas chromatography. Results showed that levels of oestrogens and industrial and household pollutants were higher in summer than in other seasons. Although oestrogens were more abundant (approximately 40 ng/L) on the southern margin of the river, levels of other pollutants were higher (approximately 124 ng/L) in the north. Phytoestrogens and sitosterol showed clear seasonal fluctuations with higher amounts of formononetin (approximately 389 ng/L), biochanin A (approximately 160 ng/L), and sitosterol (≥5 µg/L) measured in summer. The overall oestrogenic load, expressed in ethynylestradiol equivalents, was 18 ng/L for oestrogens, 0.5 ng/L for industrial and household pollutants, and 13 ng/L for phytoestrogens. Water physicochemical parameters indicate anthropogenic pollution because Σ_{nitrites,nitrates} (>1 mg/L) and phosphates (approximately 0.4 mg/L) were high. The study showed that the waters of the Lima River are subject to impacts and that levels of EDCs pose risks to the river’s biota.     

Toxicity of fluoroquinolone antibiotics to aquatic organisms

Toxicity tests were performed with seven fluoroquinolone antibiotics, ciprofloxacin, lomefloxacin, ofloxacin, levofloxacin, clinafloxacin, enrofloxacin, and flumequine, on five aquatic organisms. Overall toxicity values ranged from 7.9 to 23,000 microg/L. The cyanobacterium Microcystis aeruginosa was the most sensitive organism (5-d growth and reproduction, effective concentrations [EC50s] ranging from 7.9 to 1,960 microg/L and a median of 49 microg/L), followed by duckweed (Lemna minor, 7-d reproduction, EC50 values ranged from 53 to 2,470 microg/L with a median of 106 microg/L) and the green alga Pseudokirchneriella subcapitata (3-d growth and reproduction, EC50 values ranged from 1,100 to 22,700 microg/L with a median 7,400 microg/L). Results from tests with the crustacean Daphnia magna (48-h survival) and fathead minnow (Pimephales promelas, 7-d early life stage survival and growth) showed limited toxicity with no-observed-effect concentrations at or near 10 mg/L. Fish dry weights obtained in the ciprofloxacin, levofloxacin, and ofloxacin treatments (10 mg/L) were significantly higher than in control fish. The hazard of adverse effects occurring to the tested organisms in the environment was quantified by using hazard quotients. An estimated environmental concentration of 1 microg/L was chosen based on measured environmental concentrations previously reported in surface water; at this level, only M. aeruginosa may be at risk in surface water. However, the selective toxicity of these compounds may have implications for aquatic community structure.     

健康成年人胱抑素C水平分布及相关因素分析

目的 探讨胱抑素C在健康成年人群中的分布水平及其相关因素.方法 本研究为横断面研究,对2012年1月至2013年3月在北京协和医院体检的15 918名健康成年人,行血胱抑素C检测,统计其分布情况及与年龄、性别的关系.用线性回归法分析影响胱抑素C水平的相关因素.结果胱抑素C平均值（0.79±0.14） mg/L,95％可信区间为（0.56 ～ 1.08） mg/L.男性胱抑素C平均值（0.84 ±0.13）mg/L,高于女性平均值（0.73±0.13） mg/L.随年龄增长胱抑素C升高,男性r=0.274,P=0.000,女性r=0.470,P=0.000.对年龄进行分组后,三个年龄组内男性胱抑素C均高于女性：青年组（≤44岁）男性（0.81±0.11）mg/L（n=4289）,女性（0.68±0.09） mg/L（n=3537）,（P=0.000）;中年组（45 ～59岁）男性（0.85±0.12） mg/L （n =3921）,女性（0.75 ±0.12） mg/L（n =2858）,（P =0.000）;老年组（≥60岁）男性（0.97 ±0.18） mg/L （n=693）,女性（0.89±0.19） mg/L（n=620）,（P=0.000）.男性胱抑素C水平在青年组为（0.81 ±0.11） mg/L,中年组（0.85±0.12） mg/L,老年组（0.97±0.18） mg/L,各年龄组之间差异有统计学意义（P=0.000）.女性胱抑素C水平在青年组为（0.68±0.09） mg/L,中年组（0.75±0.12） mg/L,老年组（0.89±0.19） mg/L,各年龄组之间差异有统计学意义（P =0.000）.胱抑素C与相关因素的线性回归分析：结果显示低肌酐估计肾小球滤过率、男性、年龄增长、低水平高密度脂蛋白胆固醇、高平均动脉压、低空腹血糖水平、低体重、高三酰甘油、高BMI是高胱抑素C水平的危险因素,而身高、总胆固醇、低密度脂蛋白胆固醇不是独立的危险因素.结论 健康成年人胱抑素C水平在不同性别、年龄中的分布不同,胱抑素C水平不仅受个体一般情况影响,还与生化指标三酰甘油、高密度脂蛋白胆固醇和空腹血糖相关.     

Toxicity of chemicals to microalgae in river and in standard waters

The influence of the composition of natural waters on the toxicity of chemicals to microalgae was studied on samples representative of western European rivers. Effects of zinc, pentachlorophenol (PCP), 4-nonylphenol (4-NP), phosalone, and 2,4,5-trichloroaniline (TCA) on algal growth were tested in river waters without adding any nutrients or cosolvents, and in the International Standards Organization (ISO) medium for comparison. The mean values of effective concentrations reducing the algal growth by 50% (EC50s) after 72 h based on measured concentrations did not differ significantly in natural waters and in standard medium for 4-NP (0.5 mg/L) and phosalone (0.8-0.9 mg/L). These values were two or three times higher in rivers than in ISO medium for PCP (0.25 vs 0.1 mg/L), TCA (1.69 vs 0.73 mg/L), and zinc (0.20 vs 0.056 mg/L). Although the mean values were of the same order of magnitude, the distribution of the EC50 values ranged over 1.5 and 2 log concentrations in surface waters. Therefore, in view of a refined hazard assessment of a chemical on a local scale, it would be advisable to use the actual river water of the concerned aquatic environment in testing. Correlations between toxicity data and the physicochemical characteristics of the waters identified classic parameters such as water hardness or conductivity as factors that significantly influenced the toxicity of the ionizable compounds PCP and zinc. On the other hand, organic materials or suspended solids, but only at high levels, affected the toxicity of 4-NP, an organic chemical with high adsorption potential. No correlation could be drawn for phosalone and TCA.     

Effects of hardness, chloride, and acclimation on the acute toxicity of sulfate to freshwater invertebrates

The acute toxicity of sulfate to Ceriodaphnia dubia, Chironomus tentans, Hyalella azteca, and Sphaerium simile was assessed to support potential updates of Illinois (USA) sulfate criteria for the protection of aquatic life. The mean lethal concentrations to 50% of a sample population (LC50s), expressed as mg S04(-2)/L, in moderately hard reconstituted water (MHRW) were as follows: 512 mg/L for H. azteca, 2,050 mg/L for C. dubia, 2,078 mg/L for S. simile, and 14,134 mg/L for C. tentans. At constant sulfate (approximately 2,800 mg/L) and hardness (106 mg/L), survival of H. azteca was positively correlated with chloride concentration. Hardness also was found to ameliorate sodium sulfate toxicity to C. dubia and H. azteca, with LC50s for C. dubia increasing from 2,050 mg SO4(-2)/L at hardness = 90 mg/L to 3,516 mg SO4(-2)/L at hardness = 484 mg/L. Using a reformulated MHRW with a similar hardness but higher chloride concentration and different calcium to magnesium ratio than that in standard MHRW, the mean LC50 for H. azteca increased to 2,855 mg/L, and the LC50 for C. dubia increased to 2,526 mg/L. Acclimation of C. dubia to 500 and 1,000 mg SO4(-2)/L for several generations nominally increased mean LC50 values compared with those cultured in standard MHRW.     

Identification and antibiotic resistance of faecal enterococci isolated from water samples

We have isolated 47 strains of presumptive faecal streptococci from different water samples. Identification was made by the method of Facklam et al. (1989). Antibiotic resistance was studied on Mueller-Hinton Agar. Twelve antibiotics were tested. High-level aminoglycoside resistance (HLAR) and resistance to glycopeptides were studied. Biochemical identification of presumptive faecal streptococci isolates gave the following results: 19 Enterococcus faecalis, 12 E. faecium, 8 E. hirae, 4 E. durans and 4 E. mundtii. E. mundtii is not included among faecal enterococci. None of the strains were resistant to glycopeptides (vancomycin and teicoplanin). Three strains of Enterococci showed HLAR. Two of them were isolated from coastal bathing waters and the other from wastewater. This suggests that water could contribute to spread of HLAR enterococci and it should be a matter of concern for public health authorities.     

Evaluation of acute copper toxicity to larval fathead minnows (Pimephales promelas) in soft surface waters

The hardness-based regulatory approach for Cu prescribes an extrapolation of the toxicity-versus-hardness relationship to low hardness (< or =50 mg/L as CaCO3). Hence, the objective of the present research was to evaluate the influences of water quality on acute Cu toxicity to larval fathead minnow (Pimephales promelas) in low-hardness surface waters. Seasonal water sampling was conducted at 24 sites throughout South Carolina, USA, to determine the site-specific influences of soft surface-water conditions on acute Cu toxicity. Concurrent toxicity tests in laboratory water, matched for hardness and alkalinity (modified method), also were conducted to allow calculation of water-effect ratios (WERs). In addition, tests were conducted at recommended hardness levels (recommended method) for comparison of WER methodology in soft water. Surface-water conditions (average+/-standard deviation, n = 53) were hardness of 16+/-8 mg/L as CaCO3, alkalinity of 18+/-11 mg/L as CaCO3, and dissolved organic carbon of 6+/-4 mg/L. Dissolved Cu 48-h median lethal concentration (LC50) values varied nearly 45-fold across the dataset and greater than four-fold at individual sites. Spatial (p < 0.0001) and seasonal (p = 0.026) differences among LC50 values were determined for eight sites that had multiple toxicity results for one year. All modified WERs were greater than 1.0, suggesting that the site waters were more protective of Cu toxicity than the matched laboratory water. Some WERs generated using recommended methods were less than 1.0, suggesting limited site-specific protection. Based on these observations, extrapolation of the hardness-based equation for Cu at 50 mg/L or less as CaCO3 would adequately protect fathead minnow populations in soft surface waters. The WER results presented here demonstrate the inconsistency between hardness-based criteria and the methodology for deriving site-specific water-quality criteria in low-hardness waters.     

Influence of water chemistry on the acute toxicity of copper and zinc to the cladoceran Ceriodaphnia cf dubia

This study determined the influence of key water chemistry parameters (pH, alkalinity, dissolved organic carbon [DOC], and hardness) on the aqueous speciation of copper and zinc and its relationship to the acute toxicity of these metals to the cladoceran Ceriodaphnia cf dubia. Immobilization tests were performed for 48-h in synthetic or natural waters buffered at various pH values from 5.5 to 8.4 (other chemical parameters held constant). The toxicity of copper to C. cf dubia decreased fivefold with increasing pH, whereas the toxicity of zinc increased fivefold with increasing pH. The effect of DOC on copper and zinc toxicity to C. cf dubia was determined using natural fulvic acid in the synthetic water. Increasing DOC was found to decrease linearly the toxicity of copper, with the mean effect concentration of copper that immobilized 50% of the cladocerans (EC50) value 45 times higher at 10 mg/L, relative to 0.1 mg/L DOC at pH 6.5. In contrast, the addition of 10 mg/L DOC only resulted in a very small (1.3-fold) reduction in the toxicity of zinc to C. cf dubia. Copper toxicity to C. cf dubia generally did not vary as a function of hardness, whereas zinc toxicity was reduced by a factor of only two, with an increase in water hardness from 44 to 374 mg CaCO3/L. Increasing bicarbonate alkalinity of synthetic waters (30-125 mg/L as CaCO3) decreased the toxicity of copper up to fivefold, which mainly could be attributed to the formation of copper-carbonate complexes, in addition to a pH effect. The toxicity of copper added to a range of natural waters with varying DOC content, pH, and hardness was consistent with the toxicity predicted using the data obtained from the synthetic waters.     

Effects of temperature and sand on E. coil survival in a northern lake water microcosm

A concern for public health officials is the presence of Escherichia coli (E. coli), an indicator of fecal contamination, in monitoring recreational waters. While E. coli is unlikely to cause disease in humans, its presence may indicate other more pathogenic microorganisms. Many factors can lead to changes in the survival of E. coli outside of the animal intestine and may affect the probability of colonizing a new host. Survival of bacteria in recreational water has been linked to water temperature, and most recently to the presence of sand on the beach. This project looked at the survival of an environmental E. coli isolate in lake water. Lake water microcosms were placed at 4, 10, 14, or 25 degrees C for up to 36 d and an enzyme-substrate test (Colisure, IDEXX Corp.) was used to determine the most probable number (MPN) of E. coli/100 ml water. E. coli numbers at all temperatures declined over the duration of the experiment. The decline was most pronounced at 14 degrees C and was slowest at 4 degrees C. The presence of sand in the microcosm increased the time that E. coli survived, regardless of temperature. From a beach management standpoint, these findings indicate that E.coli may persist in the environment in cooler water longer than in the warmer water encountered in late summer.     

The effect of lethal copper solutions on the behavior of rainbow trout,Salmo gairdneri

Experiments were performed in flowthrough artificial stream apparatus to determine the attraction-avoidance responses of rainbow trout,Salmo gairdneri to lethal copper solutions (0.5, 0.75, 1.0, 2.0, 3.0 and 4.0 mg/L) when food was provided at a single source in the more contaminated water and when food was provided throughout the stream. Preference of groups of twenty test individuals for the experimental or control water was recorded at hourly intervals over 96 hr. At all concentrations, there was an initial attraction period for and subsequent avoidance of the more highly contaminated waters. Attraction was greatest in tests employing higher concentrations (3.0 and 4.0 mg/L); this attraction led to high mortality. Belated avoidance of copper solutions was observed at all levels above 0.5 mg/L maximizing at 1.0 mg/L. The EC50-96-hr value for avoidance was between 0.5 and 0.75 mg/L. With food provided only in contaminated water, fish exhibited a prolonged and intense attraction period at the lower levels (0.5 to 2.0 mg/L) when compared to dispersed feeding. No significant differences between the feeding regimes existed at the higher copper levels. Mortality curves were similar in both feeding routines. Injured fish were found in the least contaminated waters. Tagging experiments indicate a movement pattern initially toward the toxicant, with subsequent reverse migration to cleaner waters. Little movement occurred during attraction and avoidance stages. Initial avoidance was not observed at any of the tested copper concentrations. Results indicate initial attraction at all concentrations may orientate fish toward the contaminants source, and subsequent avoidance behavior had little effect on survivorship rates. Our results indicate that observed trout behavior subsequent to copper discharges contributed to high mortality. The results also suggest that behavioral response of organisms to toxicants must be incorporated into work attempting to set reasonable water-quality standards in natural water bodies.     

The microbiological quality of potable water on board ships docking in the UK and the Channel Islands: an association of Port Health Authorities and Health Protection Agency Study

Providing safe potable water onboard vessels presents particular challenges and contamination can occur directly from source waters as well as during loading, storage and distribution. Between May and October 2005, 950 potable water samples were collected from 342 ships docking at ports. Comparison with Guidelines found 9% of samples contained coliforms, Escherichia coli or enterococci and 2.8% had faecal indicators (E. coli or enterococci). Action levels of aerobic colony count (ACC) bacteria were detected in 20% (22 degrees C) and 21.5% (37 degrees C) of samples. ACC results from one-off sampling are not informative as this does not enable port health authorities to monitor ACC trends. They should be removed as a routine criterion for remedial action and vessels should adopt the WHO Water Safety Plan approach, whilst continuing to monitor water quality with public health-based indicators (e.g. chlorine residual, coliforms, E. coli and enterococci). Logistic regression analyses identified practices associated with water quality. Practices protective against coliforms, E. coli or enterococci in potable supplies were: good hose hygiene, processing water onboard, maintaining free chlorine residual at >or=0.2 mg/L. This emphasizes the importance of good hygiene during potable water loading and maintaining adequate disinfection of supplies onboard.     

Copper toxicity in relation to surface water-dissolved organic matter: biological effects to Daphnia magna

Water quality standards for copper are usually stated in total element concentrations. It is known, however, that a major part of the copper can be bound in complexes that are biologically not available. Natural organic matter, such as humic and fulvic acids, are strong complexing agents that may affect the bioavailable copper (Cu2+) concentration. The aim of this study was to quantify the relation between the concentration of dissolved natural organic matter and free Cu2+ in surface waters, and the biological effect, as measured in a standardized ecotoxicological test (48 h-median effective concentration [EC50] Daphnia magna, mobility). Six typical Dutch surface waters and an artificial water, ranging from 0.1 to 22 mg/L dissolved organic carbon (DOC), were collected and analyzed quarterly. Chemical speciation modeling was used as supporting evidence to assess bioavailability. The results show clear evidence of a linear relation between the concentration of dissolved organic carbon (in milligrams DOC/L) and the ecotoxicological effect (as effect concentration, EC50, expressed as micrograms Cu/L): 48-h EC50 (Daphnia, mobility) = 17.2 x DOC + 30.2 (r2 = 0.80, n = 22). Except for a brook with atypical water quality characteristics, no differences were observed among water type or season. When ultraviolet (UV)-absorption (380 nm) was used to characterize the dissolved organic carbon, a linear correlation was found as well. The importance of the free copper concentration was demonstrated by speciation calculations: In humic-rich waters the free Cu2+ concentration was estimated at approximately 10(-11) M, whereas in medium to low dissolved organic carbon waters the [Cu2+] was approximately 10(-10) M. Speciation calculations performed for copper concentrations at the effective concentration level (where the biological effect is considered the same) resulted in very similar free copper concentrations (approximately 10(-8) M Cu) in these surface waters with different characteristics. These observations consistently show that the presence of organic matter decreases the bioavailability, uptake, and ecotoxicity of copper in the aquatic environment. It demonstrates that the DOC content must be included in site-specific environmental risk assessment for trace metals (at least for copper). It is the quantification of the effects described that allows policy makers to review the criteria for copper in surface waters.     

Effects of Water Quality Parameters on Boron Toxicity to <Emphasis Type="Italic">Ceriodaphnia dubia</Emphasis>

The potential modifying effects of certain water quality parameters (e.g., hardness, alkalinity, pH) on the acute toxicity of boron were tested using a freshwater cladoceran, Ceriodaphnia dubia. By comparison, boron acute toxicity was less affected by water quality characteristics than some metals (e.g., copper and silver). Increases in alkalinity over the range tested did not alter toxicity. Increases in water hardness appeared to have an effect with very hard waters (>500 mg/L as CaCO₃). Decreased pH had a limited influence on boron acute toxicity in laboratory waters. Increasing chloride concentration did not provide a protective effect. Boron acute toxicity was unaffected by sodium concentrations. Median acute lethal concentrations (LC₅₀) in natural water samples collected from three field sites were all greater than in reconstituted laboratory waters that matched natural waters in all respects except for dissolved organic carbon. Water effect ratios in these waters ranged from 1.4 to 1.8. In subsequent studies using a commercially available source of natural organic matter, acute toxicity decreased with increased dissolved organic carbon, suggesting, along with the natural water studies, that dissolved organic carbon should be considered further as a modifier of boron toxicity in natural waters where it exceeds 2 mg/L.