Assessment of Several Test Methods for the Determination of the Anaerobic Biodegradability of Polymers

Anaerobic degradation of eight commercially available biodegradable polymers was compared in two anaerobic tests using digestion sludge, according to ISO 11734 and ASTM D.5210-91. Cotton, polyhydroxybutyrate/hydroxyvalerate copolymer (PHB/PHV), starch blend, thermoplastic cellulose acetate, and cellulose acetate fibers proved to be anaerobically degradable, but only a low extent of degradation was found for polylactide, polyvinylalcohol, and polycaprolactone. Both test methods gave the same overall results, but with the ISO medium, longer lag phases and greater ranges of variation in the results were observed. These effects are presumably due to low concentrations of carbon dioxide in the ISO medium. Carbon dioxide has been demonstrated to be essential for the growth of various anaerobic bacteria, notably homoacetogenic and methanogenic bacteria.     

Macrofaunal recolonisation following the intertidal placement of fine-grained dredged material

Dredged material is increasingly being regarded as a potential resource, and one of its many uses is to create and/or improve intertidal habitats (i.e. beneficial use). However, uncertainties over the longer-term environmental consequences of such schemes have, to date, limited the practice to small-scale applications in UK waters. This paper studies the macrofaunal recolonisation of fine-grained dredged material recharged concurrently at four adjacent recharge areas along the south-east coast of the UK in order to facilitate predictions regarding the recolonisation of comparable schemes and, thereby, to promote effective environmental management. During the 2-year study period, the four recharge areas were distinctly different in terms of their environmental characteristics, primarily wave exposure and bed level. These conditions resulted in different macrofaunal recolonisation rates and community structures. While the low-level, wave-sheltered area experienced rapid recolonisation, the process was delayed until 12 months post-recharge at the relatively wave-exposed areas. Bed level differences resulted in distinctly different communities in wave-sheltered areas but not under wave-exposed conditions. While we are unable to separate the effects of individual environmental variables on recolonisation, these results provide general conclusions as to the importance of environmental conditions on resulting macrofaunal communities.     

Contrasting foraging tactics by northern gannets (<Emphasis Type="Italic">Sula bassana</Emphasis>) breeding in different oceanographic domains with different prey fields

In order to forage and to provision offspring effectively, seabirds negotiate a complex of behavioural, energetic, environmental and social constraints. In first tests of GPS loggers with seabirds in North America, we investigated the foraging tactics of free-ranging northern gannets (Sula bassana) at a large and a medium-sized colony that differed in oceanography, coastal position and prey fields. Gannets at Low Arctic colony (Funk Island) 50 km off the northeast coast of Newfoundland, Canada provisioned chicks almost entirely with small forage fish (capelin Mallotus villosus, 89%), while at boreal colony (Bonaventure Island) 3 km from shore in the Gulf of St. Lawrence, Quebec, Canada, large pelagic fish dominated parental prey loads (Atlantic mackerel Scomber scombrus 50%, Atlantic herring Clupea harengus 33%). Mean foraging range and the total distance travelled per foraging trip were significantly greater at the larger inshore colony (Bonaventure) than at the smaller offshore colony (Funk Island; 138 and 452 km vs. 64 and 196 km, respectively). Gannets from Funk Island consistently travelled inshore to forage on reproductive capelin shoals near the coast, whereas foraging flights of birds from Bonaventure were much more variable in direction and destination. Birds from the Low Arctic colony foraged in colder sea surface water than did birds from the boreal colony, and dive characteristics differed between colonies, which is concordent with the difference in prey base. Differences between the colonies reflect oceanographic and colony-size influences on prey fields that shape individual foraging tactics and in turn generate higher level colony-specific foraging “strategies”.     

The effect of light and iron(II)/iron(III) on the distribution of Tl(I)/Tl(III) in fresh water systems

The distribution of aqueous Tl(I)/Tl(III) as a function of light exposure and solution properties was studied by quantifying the oxidation states after separation with ion chromatography and on-line detection with ICP-MS. Ultraviolet irradiation of aqueous solutions containing 1 microg l(-1) Tl(III) and in equilibrium with the atmosphere increases the reduction rate. In systems with photoreduction of Fe(III)(aq) a quantitative oxidation of Tl(I)(aq) was observed, notably at low pH. The process is reversible, as indicated by formation of Tl(I) when the irradiated systems were kept in the dark. In systems with colloidal silica-stabilised ferrihydrite, UV irradiation also leads to oxidation of Tl(I)(aq), but not quantitatively. It is suggested that adsorption of thallium to the ferrihydrite determines the rate of oxidation. Detectable, but not quantitative, oxidation of Tl(I)(aq) took place when natural water samples with 1 microg l(-1) Tl(I)(aq) were exposed to either sunlight or UV-light. For these samples, the reduction was not quantitative when they were kept in the dark for 24 h. The results suggest that the light dependent iron cycle in fresh water systems strongly influences the redox state of thallium.     

Ammonium Nitrate,Nitric Acid,and Ammonia Equilibrium in Wintertime Phoenix,Arizona

A secondary aerosol equilibrium model, SEQUILIB, is applied to evaluate the effects of emissions reductions from precursor species on ambient concentrations during the winter in Phoenix, Arizona. The model partitions total nitrate and total ammonia to gas-phase nitric acid and ammonia and to particle-phase ammonium nitrate. Agreement between these partitions and ambient measures of these species was found to be satisfactory. Equilibrium isopleths were generated for various ammonium nitrate concentrations corresponding to high and low humidity periods which occurred during sampling. These diagrams show that ammonia is so abundant in Phoenix that massive reductions in its ambient concentrations would be needed before significant reductions in particulate ammonium nitrate would be observed. When total nitrate is reduced by reductions in its nitrogen oxides precursor, proportional reductions in particulate nitrate are expected. Many of the complex reactions in SEQUILIB do not apply to Phoenix, and its ability to reproduce ambient data in this study does not guarantee that it will be as effective in areas with more complex chemistry. Nevertheless, the nitrate chemistry in SEQUILIB appears to be sound, and it is a useful model for addressing the difficult apportionment of secondary aerosol to its precursors.     

International Diffusion of Open Path FTIR Technology and Air Monitoring Methods: Taiwan (Republic of China)

Abstract

International cooperation and diffusion of environmental technologies is a central goal of the U.S. EPA Environmental Technology Initiative, and is of great interest to many countries. One objective is to exchange knowledge and skills concerning new monitoring technologies. In this case, the technology was open path Fourier Transform Infrared Spectrometry (op-FTIR).

Taiwan is a high-technology, newly industrialized country. Because of air pollution problems, it is interested in obtaining skills, knowledge, and instrumentation for monitoring air pollutants. In April 1994, the Industrial Technology Research Institute, Center for Industrial Safety and Health Technology (ITRI/CISH) in Hsinchu, Taiwan, requested intensive training in op-FTIR. Training was held between September 30,1994 and October 29,1994.

During the stay, the instructor provided intensive training on op-FTIR theory as well as an introduction to available instrumentation and software. The training concluded with a field demonstration of the instrumentation in a manufacturing facility. This report gives an overview of the training methods, structure, and materials in the op-FTIR training course. It will also address various problems encountered while teaching this course. In addition, the potential use for this technology in industry as well as by the Taiwanese government will be explained.     

Photocatalytic degradation of dichlorvos in aqueous TiO<Subscript>2</Subscript> suspensions

Introduction  

In the present work, we explored the kinetics of dichlorvos (2,2-dichlorvinyl dimethyl phosphate, DDVP) decay through UV-A light-induced TiO₂ photocatalysis at pH 4 and 9, and the formation of degradation intermediates and final products under specific experimental conditions. Experimental observations and theoretical considerations allowed us to suggest the degradation mechanism of DDVP by the UV/TiO₂ process in aqueous solution.     

Whole effluent assessment of industrial wastewater for determination of bat compliance

Background, aim and scope  

The applicability of the Whole Effluent Assessment concept for the proof of compliance with the “best available techniques” has been analysed with paper mill wastewater from Germany by considering its persistency (P), potentially bio-accumulative substances (B) and toxicity (T).