Influence of inter-annual variations in climatic factors on fecal coliform levels in Mississippi Sound

Information on the effects of inter-annual variations in climatic factors on fecal coliform levels in coastal waters is scarce. We used 11 years (1990–2001) of rainfall, water temperature, Pearl River stage and salinity data to assess the effects of the 1991–1992 and 1997–1998 El Niño events on fecal coliform levels in Mississippi Sound. El Niño-Southern Oscillation had major effects on Pearl River stage and water quality in the Sound. The geometric mean fecal coliform number differed among years (P=0.0001), being highest during 1991–1992 El Niño years (14.22 MPN per 100 ml) and lowest during 1999–2000 La Niña years (<1.8 MPN per 100 ml). Mean salinity varied among years (P=0.0001) from 9 ppt (1991–1992) to 21 ppt (1999–2000). Mean water temperature was lowest in 1997–1998 (14.5 °C) and highest in 1998–2000 (19.4 °C). Pearl River stage differed among years (P=0.0001), ranging from 1.96 m (1999–2000) to 3.57 m (1997–1998). Inverse relationships were observed between fecal coliform levels and salinity (r²=0.74; P=0.001) and water temperature (r²=0.69; P=0.001), whereas positive relationships were obtained with total rainfall (r²=0.52; P=0.013) and Pearl River stage (r²=0.90; P=0.0001). These relationships are useful for evaluating the potential effects of climate change on water quality and classification of shellfish growing waters in order to protect humans from consuming contaminated shellfish in shallow river-influenced estuaries.     

Identification of estrogen receptor agonists in sediments from Wenyu River, Beijing, China

Assignment of ecological impacts of contamination to specific classes of contaminants is a prerequisite for risk assessment and remediation. In this study, the combination of polarity-based fractionation, two-hybrid yeast bioassay, and chemical analysis were used to evaluate and identify estrogen receptor agonists (ER-agonists) in sediments from Wenyu River, Beijing, China. By bioassay, organic raw sediment extracts could induce significant estrogenicity and the bioassay-derived 17β-estradiol equivalents (EEQs) of raw extracts (EEQ_raws) ranged from 0.8 to 19.8 ng/g dry weight. By polarity-based fractionation, the raw extracts were separated into three fractions, i.e. non-polar, moderately polar, and polar fractions, which were subjected to bioassay and chemical analysis. The highest estrogenicity was observed in the polar fraction, which accounted for more than 78% of the total. The medium polar fraction contains PAHs and OCPs, and the estrogenic activities in this fraction contributed 3%-12% of the total in raw extract. An estrogenic activity of non-polarity fraction was negligible in compare to other two fractions. By chemical analysis and toxic equivalent calculation, major part of the estrogenicity in polar fraction could be attributed to six natural/synthetic estrogens (16%-63%), i.e. 17β-estradiol, estrone, estriol, 17α-ethynylestradiol, diethylstilbestrol, and β-estradiol-17-valerate, and to nonylphenols (26%-55%). The proposed approach has been successfully used for characterization of ER-agonists in this case study.     

Assessment of river contamination by estrogenic compounds in Paris area (France)

Wastewater treatment plants (WWTPs) receive a large spectrum of endocrine disrupting compounds (EDCs) that are partially eliminated during treatment processes and discharged into rivers. Given the lack of information in France about river contamination by EDCs, we chose to examine estrogenic potential of WWTP influents, effluents and receiving waters in Paris and its suburbs. Water samples were analyzed using gas chromatography coupled with mass spectrometry for quantifying natural and synthetic estrogens combined with an in vitro estrogenicity bioassay associated to a high pressure liquid chromatography fractionation. The four estrogens investigated, Estrone (E1), 17beta-Estradiol (E2), Estriol (E3) and 17alpha-Ethinylestradiol (EE2) were found in all WWTP and river samples at concentrations ranging from 2.7 to 17.6 ng/l and 1.0 to 3.2 ng/l, respectively. The synthetic estrogen EE2 seems more resistant to biodegradation in WWTPs and thus accounted for 35-50% of the estimated estrogenic activity in rivers. However, fractionation of samples and differences between concentrations of E1, E2, E3 and EE2 and the estrogenic activity measured by the in vitro bioassay suggested a complexity of mechanisms underlying the biological response that could not be attributed only to the investigated molecules.     

Identification of estrogen-like effects and biologically active compounds in river water using bioassays and chemical analysis

The Nackdong River is the longest river in South Korea and passes through major cities that have several industrial complexes, including chemical, electric, and petrochemical complexes, and municipal characteristics such as apartment complexes. Along the river, the Gumi region has an electric industrial complex and an apartment complex that may be possible point sources of xenoestrogens such as phenolic compounds. To identify the causative chemicals for estrogenic activity in the river water of this region, bioassay-directed chemical analysis was performed. All samples from six sampling sites (an upstream point: S1; hot spot points: S2-1, S2-2, and S2-3; and downstream points: S3, and S4) showed estrogenic activity in the E-screen assay, with bio-EEQs (17β-E₂-equivalent quantities) ranging from 25.35-677.15 pg/L. Samples from S2-2, the sampling point downstream of the junction of stream water, and domestic and industrial wastewater, contained the highest estrogenic activity. Since the bio-EEQ of the organic acid fraction (F2) of the S2-2 sample had the highest activity (823.25 pg-EEQ/L) and F2 may contain phenolic compounds, GC-MS analyses for phenolic xenoestrogens were conducted with the organic acid fractions of the river water samples. Six estrogenic phenolic chemicals, 4-NP, BPA, 4-t-OP, 4-t-BP, 4-n-OP, and 4-n-HTP, were detected, with the highest concentrations (I-EEQ) found in S2-2 (231.80 pg/L). Among these phenolic chemicals, 4-NP was the most potent estrogen (bio-EEF; 8.12 × 10^− 5) and acted as a full agonist. Furthermore, 4-NP was present at levels (2.0 µg/L in S2-2) that can induce VTG induction in fish (>1 µg/L). In addition, we confirmed that river water (S2-2) significantly increased serum VTG levels in crucian carp (Carassius auratus) in a fish exposure experiment under laboratory conditions. Therefore, phenolic xenoestrogens, especially 4-NP, may be the main causative compounds responsible for the estrogenic effect on the Nackdong River.     

Detection of estrogenic activity in sediment-associated compounds using in vitro reporter gene assays

Sediments may be the ultimate sink for persistent (xeno-)estrogenic compounds released into the aquatic environment. Sediment-associated estrogenic potency was measured with an estrogen receptor-mediated luciferase reporter gene (ER-CALUX) assay and compared with a recombinant yeast screen. The ER-CALUX assay was more sensitive to 17beta-estradiol (E2) than the recombinant yeast screen, with an EC50 of 6 pM E2 compared to 100 pM in the yeast screen. Yeast cells were unable to distinguish the anti-estrogens ICI 182,780 and (4-hydroxy)tamoxifen, which were agonistic in the yeast. Acetone-soluble fractions of hexane/acetone extracts of sediments showed higher estrogenic potency than hexane-soluble extracts in the ER-CALUX assay. Sediments obtained from industrialized areas such as the Port of Rotterdam showed the highest estrogenic potency of the 12 marine sediments tested (up to 40 pmol estradiol equivalents per gram sediment). The estrogenic activity of individual chemicals that can be found in sediments including: alkylphenol ethoxylates and carboxylates; phthalates; and pesticides, was tested. Increasing sidechain length of various nonylphenol ethoxylates resulted in decreased estrogenic activity. Of the phthalates tested, butylbenzylphthalate was the most estrogenic, though with a potency approximately 100,000 times less than E2. The organochlorine herbicides atrazine and simazine failed to induce reporter gene activity. As metabolic activation may be required to induce estrogenic activity, a metabolic transformation step was added to the ER-CALUX assay using incubation of compounds with liver microsomes obtained from PCB-treated rats. Results indicate that metabolites of E2, NP and bisphenol A were less active than the parent compounds, while metabolites of methoxychlor were more estrogenic following microsomal incubations.     

Changes in estrogen/anti-estrogen activities in ponded secondary effluent

Total estrogenic activity, measured using the yeast estrogen screen reporter gene bioassay, decreased from 60 pM (equivalent 17alpha-ethinylestradiol concentration) to an estimated 1.4 pM during a 24-hour period in which secondary effluent was held in a shallow infiltration basin. Over the same period, anti-estrogenic activity, measured as an equivalent concentration of tamoxifen, increased from 35 to 260 nM, suggesting that antagonists produced during secondary effluent storage played a role in the apparent loss of estrogenic activity. Androgenic activity, measured over the same 24-hour period using the yeast androgen screen, was near or below the method detection limit (0.7 pM as testosterone). However, the same pond samples were clearly anti-androgenic. When whole-sample extracts were separated via adsorption and stepwise elution in alcohol/water solutions consisting of 20, 40 and 100% ethanol, the sum of estrogenic activities in derived fractions was always lower than the measured estrogenic activity in the whole-sample extracts. Summed anti-estrogenic activities in the same fractions, however, always exceeded values for corresponding whole-sample extracts. Results reinforce the importance of sample preparation steps (concentration of organics followed by estrogen/anti-estrogen separation) when measuring endocrine-related activities in chemically complex samples such as wastewater effluent. The potential complexity of relationships among estrogens, anti-estrogens and matrix organics suggests that additive models are of questionable validity for estimating whole-sample estrogenic activity from measurements involving sample fractions.     

Contamination with retinoic acid receptor agonists in two rivers in the Kinki region of Japan

This study was conducted to investigate the agonistic activity against human retinoic acid receptor (RAR) α in the Lake Biwa-Yodo River and the Ina River in the Kinki region of Japan. To accomplish this, a yeast two-hybrid assay was used to elucidate the spatial and temporal variations and potential sources of RARα agonist contamination in the river basins. RARα agonistic activity was commonly detected in the surface water samples collected along two rivers at different periods, with maximum all-trans retinoic acid (atRA) equivalents of 47.6 ng-atRA/L and 23.5 ng-atRA/L being observed in Lake Biwa-Yodo River and Ina River, respectively. The results indicated that RARα agonists are always present and widespread in the rivers. Comparative investigation of RARα and estrogen receptor α agonistic activities at 20 stations along each river revealed that the spatial variation pattern of RARα agonist contamination was entirely different from that of the estrogenic compound contamination. This suggests that the effluent from municipal wastewater treatment plants, a primary source of estrogenic compounds, seemed not to be the cause of RARα agonist contamination in the rivers. Fractionation using high performance liquid chromatography (HPLC) directed by the bioassay found two bioactive fractions from river water samples, suggesting the presence of at least two RARα agonists in the rivers. Although a trial conducted to identify RARα agonists in the major bioactive fraction was not completed as part of this study, comparison of retention times in HPLC analysis and quantification with liquid chromatography-mass spectrometry analysis revealed that the major causative contaminants responsible for the RARα agonistic activity were not RAs (natural RAR ligands) and 4-oxo-RAs, while 4-oxo-RAs were identified as the major RAR agonists in sewage in Beijing, China. These findings suggest that there are unknown RARα agonists with high activity in the rivers.     

An assessment of estrogenic organic contaminants in Canadian wastewaters

A suite of 30 primarily estrogenic organic wastewater contaminants was measured in several influent/effluent wastewater samples from four municipal wastewater treatment plants and effluents from one bleached kraft pulp mill (BKME) using an ultra-trace analytical method based on gas chromatography-high resolution mass spectroscopy (GC-HRMS). In vitro recombinant yeast assay detection of the estrogenic equivalent (EEq) on whole and solid phase extracted (SPE) and fractionated wastewater was also performed. 19-norethindrone was the most frequently detected and abundant (26-224 ng/L) of all the synthetic estrogens/progesterones in the influent samples. 17alpha-ethinylestradiol was the more frequently detected synthetic estrogen/progesterone in the effluents occurring at or below 5 ng/L with some sporadic occurrences of up to 178 ng/L. The greatest levels of steroidal estrogens in municipal effluents were E1>E2>E3 which were all <20 ng/L. Nonylphenol and di(2-ethylhexyl) phthalate were found to be the highest non-steroidal synthetic compounds surveyed in both municipal influent and effluent samples, both occurring at 6-7 microg/L in municipal effluents. BKME contained relatively large amounts of the plant sterol stigmasterol (4 microg/L) but low amounts of fecal sterols, and steroidal estrogens (E2 only at 6 ng/L) when compared to the municipal effluents. In vitro EEq in the wastewater surveyed ranged from 9-106 ng E2/L and ranked from municipal influent>municipal effluent approximately BKME, with most of the estrogenicity fractionating in the 100% methanol SPE fraction followed by a secondary amount in the diethyl ether (for municipal) or methyl-tert butyl ether (for BKME) SPE fractions. Most correlations between chemical and in vitro estrogenic equivalency were weak (p>0.05 in most cases). Unexpected inverse correlations between in vitro estrogenic activity and concentrations of the estrogenic contaminant bisphenol A were found which likely contributed to the weakness of these correlations. A modified toxicity identification and evaluation procedure was continued with the SPE extracts from the more potent 100% methanol SPE fractions of municipal effluent. High performance liquid chromatography band elution retention times, based on in vitro estrogen detection, indicated that steroidal estrogens such as E2 were responsible for most of the estrogenicity of the samples. Subsequent collection and GC-MS analysis of active bands did not confirm the presence of steroidal estrogens, but expanded the possibility of phthalate esters (i.e. dibutyl phthalate) and natural sterols (i.e. beta-sitosterol) contributing to the overall estrogenic load.     

On the love strain form of naturally curved and twisted rods

Love proposed in 1944 [A.E.H. Love, A Treatise on the Mathematical Theory of Elasticity. Dover Publications, New York, 1944] that the nonvanishing (linear) strain components of a naturally curved and twist spatial rod, whose centroidal axis is along x and cross-section is in yz plane, can be represented nicely in the form ε_xx = e₁ + zk₂ − yk₃ε_xy = e₂ − zk₁ε = e₃ + yk₁ where e₁, e₂, e₃ are the strain components at y = z = 0 and k₁, k₂, k₃ are the curvatures. Functions e₁, e₂, e₃, k₁, k₂, k₃ depend on x alone. Mottershead [J. E. Mottershead, “Finite elements for dynamical analysis for helical rods”, International Journal of Mechanical Sciences, 22, (1980), pp 252–283], Pearson and Wittrick [D. Pearson and W.H. Witrick “An exact solution for the vibration of helical springs using a Bernoulli-Euler Model”, International Journal for Mechanical Sciences, 28, (1986), pp 83–96], Leung [A.Y.T. Leung “Exact shape functions for helix- elements”, Finite Elements in Analysis and Design, 9, (1991), pp 23–32], and Tabarrok and Xiong [B. Tabarrok and Y. Xiong, “On the buckling equations for spatial rods”, International Journal for Mechanical Sciences, 31, (1980), pp 179–192] have made use of the Love form. We shall show that the Love form is not even valid for two-dimensionally curved beams when shear deformation is considered. The fact that the differential length ds at point P, on the cross-section with distance y, z away from the centroidal axis is different from the differential length dx at point S on the centroidal axis has been neglected. In fact DS = (1 − k₃y + k₂z)dx, where k; are initial curvatures, which contribute to the strain components of the first order of curvatures.     

Degradation of endocrine disrupting bisphenol A by 254 nm irradiation in different water matrices and effect on yeast cells

The photodegradation of bisphenol A (BPA) in pure water, surface water and wastewater effluents was studied. The effect of different hydrogen peroxide concentrations on degradation was investigated. The rate of BPA photolysis in the presence of hydrogen peroxide was lower in wastewater effluent than in purified water.

Phenol, 1,4-dihydroxylbenzene and 1,4-benzoquinone were identified by means of HPLC as intermediate products of the photodegradation of bisphenol A.

In addition, the disappearance of the estrogenic activity of bisphenol A during irradiation was shown by the YES test. Based upon the YES test results, there was a strong decrease of estrogenic activity of parent compound after 120 min irradiation in the presence of hydrogen peroxide.     

Comparative study on organic constituents in polluted and unpolluted inland aquatic environments—V: Organic carbons and hydrocarbons in sediments

Organic carbons and hydrocarbons were analysed for polluted sediments from Tama River and sludges from night soil and sewage treatment plants in the Tokyo area and unpolluted sediments from river and reservoirs from Chichi-jima Island in the Ogasawara (Bonin) Islands to characterize their features for polluted and unpolluted aquatic environments. In addition the relationships of the features of organic constituents between waters and sediments were given. The contents of n-alkanes (C₁₄-C₃₆). squalane and unresolved complex mixture of hydrocarbons (UCMH) for the sediments from Tama River ranged from 16 to 94, 0.86–15 and 250–1100 μ g⁻¹ dry base, which are much higher than those of the sediments from Chichi-jima Island. The major constituents of hydrocarbons in the sediments and sludges from the Tokyo area were mainly odd-carbon numbered n-alkanes and squalane, whereas those of the island were only odd-carbon numbered n-alkanes. Hydrocarbons as carbon (total content × 0.851. as C₂₀H₄₂, HCC)/total organic carbon (TOC), HCC/extractable organic carbon with ethyl acetate (EOC), squalane as carbon (SqC)/TOC. SqC/EOC and UCMH/n-Alkane (C₁₅-C₃₃) values for the sediments from Tama River were much higher than those of the sediments from the island, while carbon preference index (CPI_H) values for the sediments of Tama River were considerably lower than those of the island. It was thus indicated that HCC/TOC, HCC/EOC, UCMH/n-Alkane and CPI^H values should be the important indicators of hydrocarbon pollution for aquatic environments. In addition SqC/TOC and SqC/EOC ratios are apparently useful measures of urban-industrial activities on aquatic environments.The similarity of the nature of hydrocarbons of sediments and sludges from the Tokyo area indicated that the sewage contributed considerably to urban river sediments. Further it was also indicated that hydrocarbons were concentrated in sedimentary environments, although the features of hydrocarbons in sediments are generally similar to those of waters.     

Evaluation of kinetic parameters of a sulfur-limestone autotrophic denitrification biofilm process

In this study, four kinetic parameters of autotrophic denitrifiers in fixed-bed sulfur–limestone autotrophic denitrification (SLAD) columns were evaluated. The curve-matching method was used by conducting 22 non-steady-state tests for estimation of half-velocity constant, K_s and maximum specific substrate utilization rate, k. To estimate the bacteria yield coefficient, Y and the decay coefficient, k_d, two short term batch tests (before and after the starvation of the autotrophic denitrifiers) were conducted using a fixed-bed SLAD column where the biofilm was fully penetrated by nitrate-N. It was found that K_s=0.398 mg NO₃⁻–N/l, k=0.15 d⁻¹, k_d=0.09–0.12 d⁻¹, and Y=0.85–1.11 g VSS/g NO₃⁻–N. Our results are consistent with those obtained from SLAD biofilm processes, but different from those obtained from suspended-growth systems with thiosulfate or sulfur powders as the S source. The method developed in this study might be useful for estimation of four Monod-type kinetic parameters in other biofilm processes. However, cautions must be given when the estimated parameters are used because the measurements of the biomass and the biofilm thickness could be further improved, and the assumption of sulfur being a non-limiting substrate needs to be proved.     

Determination of estrogens and estrogenic activity in wastewater effluent by chemical analysis and the bioluminescent yeast assay

A scheme of bioassay-directed analysis has been developed which combines a yeast assay screening for estrogenic activity with a liquid chromatographic-mass spectrometric (LC-MS/MS) chemical analysis, chromatographic fractionation, solid phase extraction and freeze-drying. The test scheme was applied on effluent samples collected from a municipal sewage treatment plant. The aim was to determine the substances responsible for main portion of the estrogenic activity in the samples and to compare the efficiency of different procedures for isolation and concentration of estogenicity. LC-MS/MS analyses were used for the quantification of 17beta-estradiol, estrone, estriol and 17alpha-ethinylestradiol, and the measured concentrations compared with the activities found in the yeast assay. Following conversion of the concentrations measured by LC-MS/MS to 17beta-estradiol equivalents it was concluded that freeze-drying, solid phase extraction and the chemical analysis gave comparable activities. Since estrone was the major estrogen in the effluent, this estrogen was also the major contributor to the estrogenic activity in the effluent. The estrogenic activity was equivalent to 4-7 ng/L of 17beta-estradiol. The yeast assay results from the tests of the chromatographic fractions showed that the major activity resides in the fraction where estrone, 17beta-estradiol and 17alpha-ethinylestradiol eluted. The activity of this fraction was substantially higher than the activity of the original wastewater sample. The reason for this could in part be explained by an inhibition of activity occurring in the original water sample.     

Selective removal of estrogenic compounds by molecular imprinted polymer (MIP)

A molecular imprinted polymer (MIP) was synthesized and used for selective removal of estrogenic compounds. The study on the mass balance of template as well as template leakage revealed that almost all the template could be extracted out of the polymer and no template leakage could be detected in aqueous solution. In acetonitrile, MIP could adsorb more E2 than non-template imprinted polymer (NIP) by more than 3.5 times. In aqueous solution, MIP showed reduced selectivity for E2 with a 10% difference in adsorption capacity between MIP and NIP. With an initial E1, E2, EE2 and BPA concentration of 4muM in aqueous solution and adsorbent concentrations of 0.01-0.5mg/mL, the maximum adsorption capacities of MIP for E1, E2, EE2 and BPA were 92.8, 95.8, 115.4 and 57.4mumol/g polymer, respectively. According to the adsorption isotherms for E1, E2, EE2 and BPA, a physical adsorption model containing three types of binding sites, namely, specific binding site, semi-specific binding site and non-specific binding site, was proposed to interpret the adsorption performance of MIP.     

Removal of cadmium and manganese by a non-toxic strain of the freshwater cyanobacterium Gloeothece magna.

The ability of both living and dry cells of Gloeothece magna, a non-toxic freshwater cyanobacterium, to adsorb cadmium and manganese is demonstrated in this study. Chlorophyll a content of living cells was not influenced by either cadmium or manganese concentrations, indicating that adsorption of both Cd²⁺ and Mn²⁺ by living cells of G. magna, was independent of the metabolic state of the organism. Moreover, the adsorption of both Cd²⁺ and Mn²⁺ to living cells and dry cells, was dependent on the metal concentrations, and fitted the Freundlich adsorption isotherm. However, dry cells had larger binding capacity for both Cd²⁺ (K_f=912.6) and Mn²⁺ (K_f=2398) than living cells (K_f=151.4 & 63, respectively). The role of the capsular polysaccharides, the main constituents of the cyanobacterial envelope, in binding these two metals was also studied. Polysaccharide extracts of this organism adsorbed high amounts of both Cd²⁺ (115–425 μg mg⁻¹) and Mn²⁺ (473–906 μg mg⁻¹). This study suggests that G. magna would probably be cultured in water bodies contaminated by heavy metals to ameliorate their toxicity. Also dry material of this cyanobacterium being a non-toxic species, could be used as a safe biofilter to remove toxic metals from drinking water.     

Changes in organic constituents in river water during incubation

A water sample collected from Tama River in the Tokyo area was incubated 29 days in the dark conditions at 25 ± 3°C to determine the extent and rate of the degradation of organic constituents and changes in their composition. The majority (>95%) of n-alkanes, fatty acids and sterols were degraded, although total organic carbon (TOC) and extractable organic carbon with ethyl acetate (EOC) remained in considerable amounts (>23%). The degradation of organic constituents occurred apparently in two or three steps. The rate constants for the degradation of TOC, EOC, hydrocarbons, fatty acids and sterols for the first step were 0.090, 0.18, 0.082, 1.4 and 0.23 day⁻¹, respectively. The relative abundances of total fatty acids and sterols as carbon in TOC (EOC) decreased remarkably during incubation (0–11 days) from 7.18 to 0.28% and 0.46 to 0.07%, respectively (31.2-2.2% and 2.0-0.6%, respectively), whereas those of hydrocarbons were not significantly changed.     

Uptake and release of zinc by aquatic bryophytes (Fontinalis antipyretica L. ex. Hedw.)

The zinc uptake and posterior release by an aquatic bryophyte—Fontinalis antipyretica L. Ex Hedw.—was experimentally studied in laboratory exposing the plants to different zinc concentrations in the range, 1.0–5.0 mg l⁻¹, for a 144 h contamination period, and then exposed to metal-free water for a 120 h decontamination period. The experiments were carried out in perfectly mixed contactors at controlled illumination, using mosses picked out in February 1997, with a background initial zinc concentration of 263 mg g⁻¹ (dry wt.). A first-order mass transfer kinetic model was fitted to the experimental data to determine the uptake and release constants, k₁ and k₂, the zinc concentration in mosses at the end of the uptake period, C_mu, and at the equilibrium, for the contamination and decontamination stages, C_me and C_mr, respectively. A bioconcentration factor, BCF=k₁/k₂ (zinc concentration in the plant, dry wt./zinc concentration in the water) was determined. A biological elimination factor defined as BEF=1−C_mr/C_mu was also calculated. BCF decreases from about 4500 to 2950 as Zn concentration in water increases from 1.05 to 3.80 mg l⁻¹. BEF is approximately constant and equal to 0.80. Comparing Zn and Cu accumulation by Fontinalis antipyretica, it was concluded that the uptake rate for Zn (145 h⁻¹) is much lower than for Cu (628 h⁻¹) and the amount retained by the plant decreased by a factor of about seven.     

Combination of in vitro bioassays encompassing different mechanisms to determine the endocrine-disrupting effects of river water

In this study, the total toxic effects of river water samples were assessed using a series of cell culture bioassays which encompassed different mechanisms, based on specific modes of action. River water samples were collected from three tributaries of the Youngsan River in the western portion of Korea. We confirmed that Youngsan River water was polluted with a complex mixture of estrogenic and dioxin-like compounds. The total toxic effects of the downstream water samples were found to be higher than that of the upstream water samples. In the upstream water samples, total estrogenic activity was measured to be between 0.005 and 0.049 ng-EEQ/l (17beta-estradiol-equivalent concentration) and no CYP1A activity was detected. In the downstream water samples, however, total estrogenic activity was measured to be between 0.021 ng-EEQ/l and 1.918 ng-EEQ/l, and total CYP1A activity was between 0.63 and 3.55 microg-MEQ/l (3-methylcholanthrene-equivalent concentration). When assessed according to a concentration-response curve, downstream water sample extracts exerted dual actions on estrogen receptors, depending on the concentration volume of the samples. The concentration volume range proximal to the original water sample exhibited estrogenic activity, whereas antiestrogenic activity was observed at high concentration volumes (more than 5 times concentration) in the extracts. This study involved a combination of in vitro bioassays, designed to encompass different mechanisms. The bioassays used included the estrogen receptor binding affinity test, E-screen assay, aromatase assay, and EROD assay. These tests provided a great deal of useful information regarding the potency and action modes of estrogenicity and antiestrogenicity inherent in the sampled river water. Although further study is necessary to determine the relationship between toxic responses in in vitro bioassay systems and chronic toxicity in aquatic organisms, our approach is expected to be fairly accurate with regard to the detection of endocrine-disrupting effects in an aquatic environment.     

Effect of scale and fuel type on the characteristics of pool fires for fire fighting training

This paper examines the effects of pool size and fuel type on the characteristics of pool fires. The fuels studied include hydrocarbon solvents, alcohol and their blends. The large-scale experiments were conducted on 0.445 and 1 m diameter pools in two enclosures: 41 m long×5.4 m wide×2.4 m high and 25 m long×2.7 m wide×2.4 m high, under a ventilation rate of 1–1.2 m/s. In these tests, measurements of the fuel pyrolysis mass loss rate, heat release rate (from CO₂ and CO concentrations as well as oxygen depletion), smoke extinction area (from laser attenuation), total heat flux emanating from the flame, and the yields of CO₂ and CO were made. Bench-scale tests were conducted using the same fuels and fuel blends on 100 mm× 100 mm pool fires in a Cone Calorimeter—a well-known fire test method.

The hydrocarbon+alcohol fuel blends are used to create large pool fires for fire fighting training. The aim of this study was to: (1) Formulate a fuel blend which will produce a “hot” fire for realistic fire fighting training while generating a minimal quantity of smoke to comply with the pollution regulations. (2) Investigate the effect of fuel type and scale on the properties of the pool fires. (3) Make comprehensive measurements on pool fires in tunnels which can be used for validating mathematical fire models.

This study has resulted in the formulation of a fuel blend which satisfies the requirements of fire fighting training as well as Environment Protection Authority of New South Wales. The bench and the large-scale results correlate well showing good agreement between the heat of combustion, smoke extinction area (SEA) and the yields of CO₂ and CO. The SEA increases with the CO and CO₂ yields which in turn increase with the carbon fraction and the aromatic content of the fuel/fuel blend. The SEA correlates strongly with the CO and CO₂ yields and in both the correlations, the entire data collapse on a single curve. These correlations indicate that the SEA and the CO₂ and CO yields vary mainly with the fuel type, and not so much with the pool size. The flame heat flux increases with the carbon content in the fuel.     

Zero net growth in a membrane bioreactor with complete sludge retention

A bench-scale membrane bioreactor was operated with complete sludge retention in order to evaluate biological processes and biomass characteristics over the long term. The investigation was carried out by feeding a bench-scale plant with real sewage under constant volumetric loading rate (VLR=1.2 gCOD L_react⁻¹ h⁻¹). Biological processes were monitored by measuring substrate removal efficiencies and biomass-related parameters. The latter included bacterial activity as determined through respirometric tests specifically aimed at investigating long term heterotrophic and nitrifying activity. After about 180 days under the imposed operating conditions, the system reached equilibrium conditions with constant VSS concentration of 16–18 g L⁻¹, organic loading rate (OLR) below 0.1 gCOD gVSS⁻¹ d⁻¹ and specific respiration rates of 2–3 mgO₂ gVSS⁻¹ h⁻¹. These conditions were maintained for more than 150 days, confirming that an equilibrium had been achieved between biomass growth, endogenous metabolism, and solubilization of inorganic materials.