Spatial and temporal patterns of surface water quality and ichthyotoxicity in urban and rural river basins in Texas

The Double Mountain Fork Brazos River (Texas, USA) consists of North (NF) and South Forks (SF). The NF receives urban runoff and twice-reclaimed wastewater effluent, whereas the SF flows through primarily rural areas. The objective of this study was to determine and compare associations between standard water quality variables and ichthyotoxicity at a landscape scale that included urban (NF) and rural (SF) sites. Five NF and three SF sites were sampled quarterly from March 2008 to March 2009 for specific conductance, salinity, hardness, pH, temperature, and turbidity; and a zebrafish (Danio rerio) embryo bioassay was used to determine ichthyotoxicity. Metal and nutrient concentrations at all sites were also measured in addition to standard water quality variables in spring 2009. Principal component analyses identified hardness, specific conductance, and salinity as the water variables that best differentiate the urban NF (higher levels) from rural SF habitat. Nutrient levels were also higher in the NF, but no landscape scale patterns in metal concentrations were observed. Ichthyotoxicity was generally higher in NF water especially in winter, and multiple regression analyses suggested a positive association between water hardness and ichthyotoxicity. To test for the potential influence of the toxic golden alga (Prymnesium parvum) on overall ichthyotoxicity, a cofactor known to enhance golden alga toxin activity was used in the bioassays. Golden alga ichthyotoxicity was detected in the NF but not the SF, suggesting golden alga may have contributed to overall ichthyotoxicity in the urban but not in the rural system. In conclusion, the physicochemistry of the urban-influenced NF water was conducive to the expression of ichthyotoxicity and also point to water hardness as a novel factor influencing golden alga ichthyotoxicity in surface waters.     

Interacting limits to algal growth: Light, phosphorus, and carbon dioxide availability

Most studies of limiting factors to algal growth seek to quantify the effect of individual factors. However, rates and amounts of photosynthetic carbon fixation in laboratory cultures of Anacystis nidulans show simultaneous dependence on the availability of phosphorus, carbon dioxide, and light. Thus, not all limiting factors may act independently to control algal growth in aquatic systems, and further research into the extent of such interactions is needed.     

Bacterial suppression of chlorella by hydroxylamine production

An actively nitrifying Arthrobacter sp. isolated from a lake inhibited the growth of Chlorella vulgaris. This was found to be due to hydroxylamine released by the bacterium during the oxidation of ammonium or other reduced nitrogen compounds. Plates containing Plate Count Agar streaked with Arthrobacter, accumulated 5 μg ml⁻¹ hydroxylamine-N. Chlorella was sensitive to less than 0.24 μg ml⁻¹ hydroxylamine-N. Non-nitrifying bacterial isolates of lacustrine origin did not demonstrate inhibiting activity. Our results indicate that nitrifying microorganisms may thus affect the population dynamics of algae in eutrophic lakes.     

Reactions of free chlorine with substituted anilines in aqueous solution and on granular activated carbon

Aqueous HOCl reacted with substituted anilines to form chlorinated derivatives. Some debromination and bromination products were also detected from two brominated anilines. When granular activated carbon was present, many additional products were formed. These compounds fall into several different groups: (1) N-acylation products, (2) N-carbomethoxylation products, (3) N=N dimerization products and (4) deamination and hydroxylation products.     

Biodegradability of ozonation products as a function of COD and DOC elimination by the example of humic acids

Ozone pretreatment studies of humic acids were conducted to evaluate the effects of ozonation on the biodegradability of the oxidation products as a function of COD-, DOC-elimination, decrease of u.v.-absorbance and ozone consumption. A 50–60% decrease of the COD-value and a 30% decrease of the DOC-value lead to biodegradable products (BOD₅/COD = 0.4) in most cases independent of the pH-value and the initial concentration. To reach these results 3.4–4 mg ozone are consumed per mg initial DOC. With this ozone consumption complete decolorization of the solutions is achieved and the value of u.v./DOC decreases from 4 to 0.8 m² g⁻¹.     

试论过渡时期建筑市场供求调节的方式方法

现阶段建筑市场供求调节的方式主要有:法律的、引导的、经济的、行政的、监督的、检查的。方法主要有:培育市场机制、调控市场运行;推进建筑产品价格改革;加强监督职能、监督市场运行;优化产业结构,向多元化规模经营发展;完善建筑市场法规体系等。     

Growth responses of selected freshwater algae to trace elements and scrubber ash slurry generated by coal-fired power plants

In laboratory studies, the freshwater algae Ankistrodesmus falcatus, Scenedesmus obliquus, Selenastrum capricornutum, and Microcoleus vaginatus were exposed to potential pollutants from coal-fired power plants, and their growth responses were evaluated. Using a modification of the EPA Algal Assay Procedure Bottle Test, algae were incubated in media containing As(V) as Na₂HAsO₄ · 7H₂O, Cd(II) as CdSO₄, Hg(II) as HgSO₄, Se(VI) as Na₂SeO₄, in solution, and scrubber ash slurry generated at a western U.S. coal-fired power plant complex. First significant inhibition levels as well as algistatic-algicidal levels are reported. The median effective concentration (EC50) values for the potential pollutants ranged from 0.048–30.761 mg l⁻¹ (0.00064–0.41058 M) As(V), 0.005–0.019 mg l⁻¹ (0.00004–0.00017 M) Cd(II), 0.033–0.253 mg l⁻¹ (0.00016–0.00126 M) Hg(II), 0.033–8.511 mg l⁻¹ (0.00042–0.10779 M) Se(VI), and 3.048–15.417% scrubber ash slurry extract (SASE).     

A new quality factor for the building stone industry: a case study of stone blocks,slabs, and tiles

In building stones, discontinuities, non-uniformity, and irregular shape are among the problems that reduce the quality of products. Stone blocks, slabs, and tiles are the main products of quarries and stone processing plants. Quantifying the quality is a key factor in valuation of these products. This paper proposes a quality factor formula to determine the quality of stone blocks (three-dimensional) and products from stone processing plants (two-dimensional). This factor, which shows the uniformity and esthetic index of a piece of stone, is determined based on the shape quality (α), number, size, and esthetic quality (β) of the pieces and the discontinuity factor (γ) that separates the pieces. The quality factor is defined in a way that each previously mentioned characteristic of a piece is involved in the quality factor formula calculation. The quality factor ranges between 0 and 1 and can be expressed as a percentage. The proposed quality factor was calculated for a number of different stone blocks, slabs, and tiles to examine the validity of the quality factor formula. The results showed that the shape quality is the most significant parameter in determining the quality of stone blocks in quarries. Moreover, in processing plant products the esthetic quality and the number of stone pieces in a product are the key factors for determination of their quality. The discontinuity factor is a parameter that reduces the quality of stone products significantly. Furthermore, the quality factor formula can be used as a convenient tool for classifying the products of quarries and stone processing plants.

     

Coagulation of turbid water and softening of hardwater with Moringa oleifera seeds

In this study, the effects of 5 process variables on softening hardwater and coagulation of surface water with a M. oleifera seed extract were investigated. Multiple regression analysis showed a strong correlation (R² (adj.) = 0.99 between M. oleifera seed dosage and the initial hardness of synthetic hardwater. Since M. oleifera is known to be a polyelectrolyte, the softening mechanism is likely to be adsorption. An adsorption isotherm developed was approximately linear and conformed to the Langmuir type. For the coagulation studies, the water samples were from three rivers in Kano, Nigeria over a three month period during the rainy season (June‐August 1994). The turbidity of the water sample varied from 105–350 NTU. When used as primary coagulant, M. oleifera was able to achieve up to 99% turbidity removal for two of the water samples at the optimum dosage of 250 mg/l. For the third water sample, the optimum dosage was 450 mg/l which is assumed to be due the high value of the colour of the water. Saving in alum usage of up to 40% was achievable when M. oleifera was used in conjunction with alum.     

A simple method to measure the gas‐phase SVOC concentration adjacent to a material surface

Assessing human exposure to semivolatile organic compounds (SVOCs) emitted from materials and products is difficult because methods are not available to easily measure the key emission parameters. A simple method based on a passive sampling technique was thus developed to measure the gas‐phase SVOC concentration (y₀) immediately adjacent to the material surface in a consumer product. The method employs standard stainless steel thermal desorption tubes, with values of y₀ and an additional unknown parameter, K, the tube surface/air partition coefficient inside the desorption tube, obtained by fitting a diffusion model to the sampling data. Phthalates in two types of polyvinyl chloride flooring were selected to test the method. The values of y₀ and K agree well with those measured in independent chamber tests. The y₀ measurement method is shown to be applicable to chemicals with a wide range of vapor pressures. This novel method should be useful for assessing potential exposure to SVOCs in consumer products as well as for exposure‐based prioritization of chemicals and their associated products in indoor environments.     

Mode of bacterial inactivation by chlorine dioxide

This study was conducted to examine the effects of chlorine dioxide on dehydrogenase enzymes, protein synthesis, and deoxyribonucleic acid of bacteria in order to elucidate the mode of action of chlorine dioxide. Experiments were carried out in a specially designed unit which permitted sampling for bacterial survivals at time intervals from 5 to 1800 s after the addition of the disinfectant. Bacterial numbers were determined by the pour plate technique. The total dehydrogenase activity of Escherichia coli was determined by the colorimetric estimation of triphenyl formazan, and cell extracts were assayed for their ability to incorporate radioactive phenylalanine into protein. DNA extracted from chlorine dioxide-treated Haemophilus influenzae was tested for its ability to transform competent cells. Partially purified DNA was also exposed to chlorine dioxide and tested for transformability.Experimental results show that total dehydrogenase enzymes were completely inhibited within the first 5 s of reaction even while considerable numbers of bacteria remained viable. Protein synthesis was partially inhibited by chlorine dioxide and the extent of inhibition was found to be proportional to the initial chlorine dioxide dosage. Glutathione did not reverse the effect of chlorine dioxide on bacterial viability, total dehydrogenase activity or protein synthesis. When whole cells of H. influenzae were exposed to chlorine dioxide, the DNA transforming activity was not affected. Similarly, when a partially purified extract of H. influenzae DNA was treated with chlorine dioxide, no inhibition of DNA transformation occurred within the first minute of reaction. Moreover, after a contact time of 5 min or more, a very high chlorine dioxide dose of 20 mg l⁻¹ produced only a slight inhibition of DNA transforming function. Thus, the primary site of action of chlorine dioxide on bacteria must lie elsewhere in the cell other than in the dehydrogenase enzymes, the protein synthesizing complex or DNA, although inhibition of protein synthesis may have a contributory lethal effect.     

The effectiveness of five natural products against three species of harmful algae

The effects of five natural products on the growth of three harmful algae species including Chattonella marina Hara et Chihara, Alexandrium tamarense Balech and Karenia mikimotoi (Miyake & Kominami ex Oda) G. Hansen & Ø. Moestrup were observed. Four products including ε‐polylysine, betaine, stachydrine and berberine exhibited selectively inhibitory effects against the three algae. However, the other product chitosan had no obvious inhibition against the above algae. Berberine and ε‐polylysine exhibited relatively higher inhibitory capability against C. marina, and betaine had the highest inhibitory effect against A. tamarense. While only berberine could effectively inhibit the growth of K. mikimotoi with LC_{50, 120} at 3.1 mg/L. The fast inhibitory effect against K. mikimotoi and environmental safety of berberine suggested that it might be a potential algaecide against K. mikimotoi.     

The Collision of Scarcity and Expendability in Architectural Culture of the 1960s and 1970s

Architecture as a practice assimilates contradictions. Nowhere is this more apparent than in approaches to materials and sustainability. New finishes, details and products are continually specified and often fetishised, while architects are at pains to show their minimal impact on the environment. Steve Parnell highlights an era in the pages of Architectural Design in the late 1960s and early 1970s that congregated these incongruities by simultaneously advocating low-energy solutions and expendability, most notably the inflatable.     

Influence of temperature and time of incubation on the estimation of bacterial numbers in tropical surface waters

A pour plate procedure employing 10 plates at each of 2 dilutions was used to determine the Aerobic Plate Count of bacteria in tropical surface water. The counts were conducted on 3 water samples at each of the following incubation temperatures: 20, 25, 30, 35 and 40°C. Colonies appearing on the plates were counted after 24, 48, 72, 96 and 120 h incubation. Following statistical analysis (P = 0.05) of the results it is recommended that 30°C for 72 h be adopted as a standard incubation regime for Aerobic Plate Counts of bacteria in warm tropical waters.     

Comparative study on organic constituents in polluted and unpolluted inland aquatic environments-IV Indicators of hydrocarbon pollution for waters

The ratios between organic carbons and hydrocarbon constituents were compared for polluted river waters from the Tokyo area and unpolluted river, brook, reservoir and pond waters from the Ogasawara (Bonin) Islands to derive indicators of hydrocarbon pollution fossil fuels and their products and both combustion products, and industrial products. The hydrocarbons as carbon (HCC)/total organic carbon (TOC). HCC extractable organic carbon with ethyl acetate (EOC), squalane as carbon (SgC),TOC, SqC/EOC, and unresolved complex mixture of hydrocarbons (UCMH)n-Alkane (C₁₅-C₃₃) ratios of the waters from the Tokyo area were much higher than those of the waters from the Ogasawara Islands. The values of carbon preference index (CPI₁₁) for n-alkanes (C₁₄-C₁₄) close to unity were found in all the water samples from the Tokyo area. They are considerably lower than those of the water samples from the Ogasawara Islands. These results indicate that the HCC TOC, HCC/EOC UCMH/n-Alkane and CPI₁₁ values are the important indicators of hydrocarbon pollution. Further, it was suggested that the SqC/TOC and SqC/EOC ratios are useful indicators of urban-industrial activities on water systems.     

Effects of activated carbon on the reactions of combined chlorine with phenols

In the presence of ammonia, prechlorination in drinking water treatment results in contact of combined chlorine (monochloramine) with activated carbon, which is used to remove organic compounds from water. Monochloramine reacts very slowly with phenolic compounds in aqueous solution, giving low yields of chlorinated phenols. When monochloramine reacts with phenols adsorbed on granular activated carbon (GAC), however, several oxidized products, principally hydroxylated biphenyls, are formed. Some of the hydroxylated biphenyls are chlorinated (hydroxylated PCBs). Their formation is particularly important because of their potential toxicity. Such compounds are major reaction products from chlorophenol, but they are also formed in small amounts from nonchlorinated phenols. Most of the monochloramine-GAC-phenolic compound reaction products are also produced in similar reactions with free chlorine, indicating that similar reaction mechanisms (free radical mechanisms) take place on carbon's surface. No organic compounds are produced from the reaction of monochloramine with GAC alone.     

Removal of phenols from aqueous solutions using tyrosinase immobilized on polymer carriers and inorganic coagulants

The methods for the removal of phenolic compounds (0.5–10 mmol/dm³) from aqueous solutions and selective separation of its mixtures based on the oxidation of phenols using tyrosinase isolated from Agaricus bisporus and immobilized on polymer carriers as well as the removal of bioconversion products by inorganic coagulants were developed.     

Accumulation of zinc, cadmium and lead by field populations of Lemanea

A study has been made of the concentrations of zinc, cadmium and lead in populations of the red alga Lemanea growing in fast-flowing rivers in Britain, France. Germany, Ireland and Sardinia (Italy). The sites were selected to provide a wide range of aqueous concentrations of these metals. Many of the sites are influenced by past or present mining activities and Lemanea was found at aqueous concentrations of zinc up to 1.16 mg 1⁻¹. In contrast to previous studies with filamentous green algae, no evidence could be found to support the hypothesis that populations differ genetically in their ability to tolerate these heavy metals. Samples of alga consisted of pooled 2 cm long terminal tips of filaments detached from approx. 1 cm² rock surface. Significant positive correlations were found between the logarithm of the mean concentration of zinc, cadmium and lead in four such samples collected from within 10 m reaches at 59 sites and the logarithm of the concentration of each metal in both unfiltered and filtered water. The enrichment ratios for each metal decreased with increasing aqueous metal concentrations. Although the aqueous concentrations of the three metals were strongly intercorrelated, differences in the ratio of metal concentrations were reflected in the composition of Lemanea filaments. The results suggest that high levels of calcium (and/or magnesium) result in decreased uptake of zinc. Intensive sampling from a single population showed that part of the zinc content of filaments is sensitive to short-term fluctuations in concentrations in the surrounding water. In the particular population studied this was about 20%; a similar percentage could be eluted in the laboratory with EDTA. Transplants of Lemanea were made between reaches with different aqueous concentrations of zinc and in all cases the zinc concentration in filament tips increased or decreased to stabilise at a concentration similar to that in filaments native to the reach. It is suggested that chemical analyses of natural or transplanted populations of Lemanea could provide a valuable aid in monitoring contamination of rivers by zinc, cadmium or lead.     

Reaction of ozone with Trans-trans muconic acid in aqueous solution

The ozonation of trans-trans muconic acid in aqueous solution (pH 3) leads to the formation of fumaric acid aldehyde, glyoxal, glyoxylic acid and formic acid which are oxidized into stable end products of oxalic acid, mesoxalic acid and CO₂ as the reaction goes on. Besides unstable organic peroxides H₂O₂ is observed. However, at pH 7 and pH 8 organic peroxides are not detected. Only smaller amounts of H₂O₂ than at pH 3 are formed.The specific ozone consumption was 3.2 mmol of O₃ mmol⁻¹ of acid until complete elimination of muconic acid. The reaction mechanism is discussed on the basis of quantitative tracking of the oxidation products.The reaction rates of muconic acid and of the oxidation products with ozone are compared with those of substituted aromatics.