Wastewater disinfection by peracetic acid: assessment of models for tracking residual measurements and inactivation.

With its potential for low (if any) disinfection byproduct formation and easy retrofit for chlorine contactors, peracetic acid (PAA) or use of PAA in combination with other disinfectant technologies may be an attractive alternative to chlorine-based disinfection. Examples of systems that might benefit from use of PAA are water reuse schemes or plants discharging to sensitive receiving water bodies. Though PAA is in use in numerous wastewater treatment plants in Europe, its chemical kinetics, microbial inactivation rates, and mode of action against microorganisms are not thoroughly understood. This paper presents results from experimental studies of PAA demand, PAA decay, and microbial inactivation, with a complementary modeling analysis. Model results are used to evaluate techniques for measurement of PAA concentration and to develop hypotheses regarding the mode of action of PAA in bacterial inactivation. Kinetic and microbial inactivation rate data were collected for typical wastewaters and may be useful for engineers in evaluating whether to convert from chlorine to PAA disinfection.     

Duration of vaginal bleeding and trisomy at prenatal diagnosis

In the case-control study of 118 women with autosomal trisomy identified at prenatal diagnosis and their 442 karyotypically normal matched controls, we found that there was no overall association between risk of trisomy and the presence of vaginal bleeding during pregnancy. However, a lengthy duration of bleeding appears to predict increased risk of trisorny.     

Fate and degradation of triasulfuron in soil and water under laboratory conditions

The behavior and fate of triasulfuron (TRS) in water and soil systems were examined in laboratory studies. The degradation of TRS in both buffer solution and soil was highly pH-sensitive. The rate of degradation could be described with a pseudo first-order kinetic and was much faster at pH 4 than at pH 7 and 9. Aqueous hydrolysis occurred by cleavage of the sulfonylurea bridge to form 2-(2-chloroethoxy) benzenesulfonamide (CBSA) and [(4-methoxy-6-methyl-1,3,5-triazin-2-yl)amino] (AMMT). AMMT was unstable in aqueous solutions in any pH condition but it degraded more quickly at pH 4 and 9. CBSA did not degrade in aqueous solutions or in enriched cultures but it underwent a quick degradation in the soil. The rates of TRS degradation in sterile and non-sterile soils were similar, suggesting that microorganisms played a minimal role in the breakdown process. This hypothesis is supported by the results of studies on the degradation of TRS by enriched cultures during which the molecule underwent a prevalently chemical degradation.     

Soft intervention technology as a tool for integrated coastal zone management

After introducing soft defence techniques as an alternative to hard defence techniques, the need is emphasized to consider the coastal area as an integral system. By recalling the main driving factors for coastal management: conflict resolution, resilience and sustainability, we logically arrive at the concepts of ecological engineering and ecotechnology, which are increasingly acknowledged as possible solutions to achieve sustainable use of coastal space as a resource. In this context, we refer to the principles of self design and of ecosystem conservation. In order to deal with real situations we are in need of fundamental ‘tools’ for the application of the soft intervention technology approach. We therefore introduce the concept of physiographic units and develop an initial elaboration for a coastal stretch and for coastal wetlands. The latter deserve more attention because of the already established practices of ecotechnology, at least as far as water and soil quality are concerned, but certainly also concerning morphology, especially in the future. We conclude by briefly discussing how activities undertaken in two research projects currently being conducted under the framework of the Marine Science and Technology Program of the Commission of the European Communities are expected to contribute to the concepts introduced here.     

Uncertainty in integrated coastal zone management

Uncertainty plays a major role in Integrated Coastal Zone Management (ICZM). A large part of this uncertainty is connected to our lack of knowledge of the integrated functioning of the coastal system and to the increasing need to act in a pro-active way. Increasingly, coastal managers are forced to take decisions based on information which is surrounded by uncertainties. Different types of uncertainty can be identified and the role of uncertainty in decision making, scientific uncertainty and model uncertainty in ICZM is discussed. The issue of spatial variability, which is believed to be extremely important in ICZM and represents a primary source of complexity and uncertainty, is also briefly introduced. Some principles for complex model building are described as an approach to handle, in a balanced way, the available data, information, knowledge and experience. The practical method of sensitivity analysis is then introduced as a method for a posterior evaluation of uncertainty in simulation models. We conclude by emphasising the need for the definition of an analysis plan in order to handle model uncertainty in a balanced way during the decision making process.     

Photo-Stabilisation and UV Blocking Efficacy of Coated Macro and Nano-Rutile Titanium Dioxide Particles in Paints and Coatings

Surface treated macro and nanoparticle TiO₂ samples have been prepared, characterised and their efficiency as UV blockers evaluated in clear coatings and paints. The particle size of the ‘base’ TiO₂ has been optimised to block UV radiation and the surface treatment developed to deactivate the photocatalytic activity of the surface of the TiO₂ particles. The resultant UV blockers have been evaluated in both solvent and water-based clear coatings. Nanoparticle TiO₂ has been prepared from ‘seed’ and the particle size was controlled by calcination. It was found that the choice of particle size is a compromise between UVA absorption, UVB absorption, visible transmission and photoactivity. It has been demonstrated that TiO₂ with a crystallite size of 25 nm yields a product with the optimum properties. A range of dispersants was successfully used to disperse and mill the TiO₂. Both organic and inorganic dispersants were used; 2-amino-2-methyl-1-propanol and 1-amino-2-propanol (MIPA) and P₂O₅ and Na₂SiO₃ respectively. The surface of the nano-TiO₂ was coated with mixed oxides of silicon, aluminium, zirconium and phosphorous. Addition of the resultant coated nano-rutiles to an Isocyanate Acrylic clear coating prolonged the lifetime of that coating compared to the blank. Generally, a surface treatment based on SiO₂, Al₂O₃ and P₂O₅ was more successful than one based on ZrO₂, Al₂O₃ and P₂O₅. Higher addition levels of the surface treatment were beneficial for protecting the polymeric coating. The UV blocker products were also evaluated in a water-based acrylic, first a water-based dispersion of the UV blocker was prepared before addition to the acrylic. The dispersions and resultant acrylic thin films were evaluated using UV/Vis spectroscopy and durability assessed. The ratio of absorbance at 300:500 nm for the water-based dispersion was shown to be a good predictor of both the transparency of the resultant acrylic thin film and the durability of that film, in terms of weight loss. Macro grade titanium dioxide pigments were also prepared and coated with treatments of silica, alumina and siloxane and their photo-stabilising activity in alkyd paint film assessed and found to be directly related to the electron–hole pair mobility and trapping as determined by micro-wave spectroscopy.     

Trace Element Concentrations and Bioindicator Responses in Tree Swallows from Northwestern Minnesota

Extremely high concentrations of cadmium (3.5 μg/g dry wgt.) and elevated concentrations of chromium (>10 μg/g dry wgt.) and mercury (1.6 μg/g dry wgt.) were reported in waterbird tissues at Agassiz National Wildlife Refuge in northwestern Minnesota in 1994. Tree swallows (Tachycineta bicolor) were studied during 1998–2001 at three drainages into the Refuge, two pools on the Refuge, and at a nearby reference location to document whether high levels of contaminants were still present, and if so to quantify the source and severity of the contamination. Trace elements were measured in tree swallow eggs, livers, and diet. Reproductive success and bioindicator responses were monitored. In 2000, water was drawn down on Agassiz Pool, one of the main pools on the Refuge. This presented an opportunity to evaluate the response of trace element concentrations in the diet and tissues of tree swallows after reflooding. High concentrations of trace elements were not detected in swallow tissues, nor were there differences among locations. Less than 20% of swallow samples had detectable concentrations of cadmium or chromium. Mercury concentrations were low and averaged <0.25 μg/g dry wgt. in swallow tissues. Trace elements, including mercury, did not increase in tree swallows following the 2000 drawdown at Agassiz Pool. Hatching success and survival of nestlings to 12 days-of-age for tree swallows on the Refuge were similar to the national average and consistent with background trace element concentrations. Bioindicator measurements were within the normal ranges as well.     

Development and validation of LC-MS/MS method for the determination of Ochratoxin A and its metabolite Ochratoxin α in poultry tissues and eggs

The objective of this study was to develop a liquid chromatography tandem mass spectrometry (LC-MS/MS) method for the determination of Ochratoxin A (OTA) and Ochratoxin α (OTα) in poultry tissues and eggs. The two toxins were extracted by a mixture of acetonitrile/water, purified with a reversed phase C18 solid phase extraction column (SPE) and determined by LC-MS/MS. The LC-MS/MS method performances were evaluated in terms of linearity in solvent and in matrix (ranged from 0.5 to 15.10 µg L^?1 for OTA and from 0.60 to 17.85 µg L^?1 for OTα), limit of detection (LOD), limit of quantitation (LOQ), specificity, accuracy and precision in repeatability conditions. Recovery experiments were performed by spiking poultry liver, kidney, muscle and eggs around 1 µg kg^?1 and 10 µg kg^?1. LODs were 0.27 and 0.26 µg kg^?1 while LOQs were fixed at 1.0 and 1.2 µg kg^?1 for OTA and OTα, respectively. Main recoveries for OTA ranged from 82 to 109% and for OTα ranged from 55 to 89%. The values of within-laboratory relative standard deviation (RSD_r) were equal to or below 20%. Considering the results obtained and that all analytical performance criteria were fulfilled, the new extraction and purification method developed for OTA and OTα determination in animal tissues and eggs was found appropriate for control laboratories and research activities designed to ensure food safety.