16S ribosomal RNA tools identify an unexpected predominance of Paenibacillus-like bacteria in an industrial activated sludge system suffering from poor biosolids separation.

Molecular biology tools targeting 16S ribosomal RNA (16S rRNA) were used to identify a predominant bacterial population in a full-scale dairy wastewater activated sludge system suffering from poor biosolids separation. Gram and acridine orange staining indicated that viable, Gram-positive microorganisms were present in samples removed from the influent waste stream and represented approximately 50% of total cell counts in samples removed from the mixed liquor. Subsequently, the "full-cycle 16S rRNA approach" showed that phylogenetic relatives of Paenibacillus spp., a low guanine-plus-cytosine percent DNA-content, Gram-positive microorganism, represented up to 30% of total 4,6-diamidino-2-phenylindole (DAPI)-stained cell counts in samples of mixed liquor. Although fluorescent in situ hybridizations with 16S rRNA-targeted oligonucleotide hybridization probes identified Paenibacillus-like spp. in samples removed from the influent waste stream, their abundance was less than 10% of total stained cell counts. Results of this study suggest that Paenibacillus-like spp. were present in low abundance in the influent waste stream, increased in relative abundance within the treatment system, and should be examined further as a candidate bacterial population responsible for poor biosolids separation. This study demonstrates that the full-cycle 16S rRNA approach can be used to identify candidate bacterial populations that may be responsible for operational upsets in full-scale activated sludge systems without prior information from cultivation or microscopic analyses.     

Bacillus thuringiensis, nucleopolyhedrosis virus,and pheromones: Environmental considerations and uncertainties in large-scale insect control

The mode of action, extent of use, and the current knowledge on environmental fate and toxicity of three biological insecticides [Bacillus thuringiensis (B.t.), nucleopolyhedrosis virus (NPV), and pheromones] are reviewed. Data gaps, environmental uncertainties in any large-scale use, and proposed registration guidelines which may lead to more extensive use are discussed. B.t. disappears rapidly from plant foliage on exposure to sunlight and/or moisture, although it may persist in dry soil for several months or years. Foliar-applied NPVs are also inactivated by sunlight; the halflife on cotton leaves is 20–25 h. In the soil, NPVs may remain active for several years. Pheromones volatilize readily and do not persist in plant or in soil. Limited available data indicate that B.t. and pheromones do not persist in aquatic environments; quantitative data are unavailable for NPVs. Based on bioassay data, the three insecticides exhibit undetectable to low toxicity to nontarget organisms; there are also no reports of human disease or injury due to exposure to these pesticides and no bioaccumulation is expected with normal application. Except for B.t. which has been used in a limited large-scale applications, pest control uses of NPVs and pheromones are still in experimental stages. Areas of uncertainties requiring research and development include potential adverse health and ecological impacts in any large-scale and widespread use and efficacy and cost relative to synthetic chemical pesticides.     

Estimation and comparison of night-time OH levels in the UK urban atmosphere using two different analysis methods

Night-time OH levels have been determined for UK urban surface environments using two methods,the decay and steady state approximation methods.Measurement data from the UK National Environmental Technology Centre archive for four urban sites(Bristol,Harwell,London Eltham and Edinburgh) over the time period of 1996 to 2000 have been used in this study.Three reactive alkenes,namely isoprene,1,3-butadiene and trans-2-pentene were chosen for the calculation of OH levels by the decay method.Hourly measurements o...     

CONCENTRATION AND SOURCES OF FECAL AND ORGANIC POLLUTION IN AN AGRICULTURAL WATERSHED1

ABSTRACT: Fecal contamination and organic pollution of an agricultural drainage in northeast Indiana was high. Bacterial counts (total coliform, TC; fecal coliform, FC; and fecal streptococcus, FS) and biochemical oxygen demand (BOD) were used to assess waste concentrations. Coliform counts indicated that sections of the drainage receiving septic effluent had waste concentrations far in excess of public health standards (mean FC = 550,000/100 ml). Areas of drainage remote from septic tank pollution were found to occasionally meet federal public health standards for whole body contact recreation but generally these areas had twice the allowable limit of 200 FC/100 ml. Bacterial contamination was highest during runoff events when the median values for TC, FC, and FS were 5, 3, and 17 times greater, respectively, than the median values during low stream discharge. Surface flows carried contaminants from unconfined livestock operations and fecally contaminated sediment was transported by high waters. During one runoff event a BOD loading of 36.7 kg/km² was recorded and the peak BOD concentration observed was 16 mg/l. A discharge of liquid manure from a confined livestock operation caused a major fish kill. Pollution from septic tanks and unconfined livestock is greatest at high stream discharge when dilution reduces the impact on aquatic life.     

Effective biological control of Salvinia molesta in the Senegal River by means of the weevil Cyrtobagous salviniae

The invasion of Salvinia molesta in the Lower Senegal River Delta in Mauritania and Senegal in 1999 posed a serious threat to the socioeconomic conditions of the local people as well as to wetland biodiversity. Eventually, an effective biological control of S. molesta was obtained by means of the weevil Cyrtobagous salviniae, which was introduced in the river in Senegal and Mauritania in May 2000 and in Senegal in April 2001. In October 2001, it became apparent that the weevils were doing a magnificent job. The color of the plants was turning from green to dark-brown or black, and subsequently the plants started to sink to the bottom. Detailed monitoring of the dispersal of C. salviniae in November-December 2001 confirmed the visual observations of the outcome of biological control. In April 2002, it could be concluded that S. molesta was no longer a problem in the Senegal River.     

Analysis of microbiological characteristics of wastewater along the polishing sequence of a treatment plant.

Microbial populations were studied by plate counts and flow cytometry along the polishing sequence of a wastewater plant. The comparison between plate count and flow cytometry showed comparable trends, but plate counts detected less than 10% of the total intact bacteria counted by flow cytometry. Six months monitoring showed that, in spite of the high ozone doses, the disinfection effect of ozonation was insignificant. This is in agreement with the variability of ozone demand, not only related to chemical oxygen demand or total suspended solids. Membrane-intact bacterial population decreased after ozonation, slightly regrew between ozone and biological activated carbon (BAC), and sharply increased after BAC, probably for damaged bacteria regrowth and saprophytes release; BAC effluent had the highest bacterial counts. Preliminary investigations on the effluent microbial composition showed that the beta Proteobacteria subclass is the most represented in the BAC effluent, whereas the alpha subclass is the most sensitive to ozone effect.     

Chapter one: exposure measurements

Determining human exposure to suspended particulate concentrations requires measurements that quantify different particle properties in microenvironments where people live, work, and play. Particle mass, size, and chemical composition are important exposure variables, and these are typically measured with time-integrated samples on filters that are later submitted to laboratory analyses. This requires substantial sample handling, quality assurance, and data reduction. Newer technologies are being developed that allow in-situ, time-resolved measurements for mass, carbon, sulfate, nitrate, particle size, and other variables. These are large measurement systems that are more suitable for fixed monitoring sites than for personal applications. Human exposure studies need to be designed to accomplish specific objectives rather than to serve too many purposes. Resources need to be divided among study design, field sampling, laboratory analysis, quality assurance, data management, and data analysis phases. Many exposure projects allocated too little to the non-measurement activities.     

A Regional Approach to Projecting Land-Use Change and Resulting Ecological Vulnerability

This study explores ecological vulnerability to land-use change in the U.S. Mid-Atlantic Region by spatially extrapolating land and economic development, and overlaying these projections with maps of sensitive ecological resources. As individual extrapolations have a high degree of uncertainty, five methods with different theoretical bases are employed. Confidence in projections is increased for counties targeted by two or more projection methods. A county is considered at risk if it currently supports three or more sensitive resources, and is projected to experience significant growth by the year 2010 by two or more methods. Analysis designated 19 counties and two cities as at risk, highlighting within a large region the priority areas where state and regional efforts would contribute the most to integrating environmental considerations into the process of land development. The study also found that potentially severe ecological effects of future land-use change are not limited to the outskirts of major urban areas. Recreational demands on smaller communities with mountain and coastal resources are also significant, as are initiatives to promote economic development in rural areas of high ecological quality. This approach provides a comprehensive overview of potential regional development, leading to an objective prioritization of high-risk areas. The intent is to inform local planning and decision-making so that regional and cumulative ecological degradation are minimized.