Effect of food concentration and type of diet on <Emphasis Type="Italic">Acartia </Emphasis>survival and naupliar development

We have performed life table experiments to investigate the effects of different food types and concentrations on the larval development and survival up to adulthood of Acartia tonsa. The food species offered comprised a wide taxonomic spectrum: the pigmented flagellates Isochrysis galbana, Emiliania huxleyi, Rhodomonas sp., Prorocentrum minimum, the diatom Thalassiosira weissflogii, grown on medium offering enriched macronutrient concentrations and the ciliate Euplotes sp. initially cultured on Rhodomonas. For the ciliate species, also the functional response was studied. In order to avoid limitation by mineral nutrients, food algae have been taken from the exponential growth phase of the nutrient replete cultures. The suitability of Rhodomonas as a food source throughout the entire life cycle was not a surprise. However, in contrast to much of the recent literature about the inadequacy or even toxicity of diatoms, we found that also Thalassiosira could support Acartia-development through the entire life cycle. On the other hand, Acartia could not complete its life cycle when fed with the other food items, Prorocentrum having adverse effects even when mixed with Rhodomonas and Thalassiosira. Isochrysis well supported naupliar survival and development, but was insufficient to support further development until reproduction. With Emiliania and Euplotes, nauplii died off before most of them could reach the first copepodite stages. Acartia-nauplii showed a behavioral preference for Euplotes-feeding over diatom feeding, but nevertheless Euplotes was an insufficient diet to complete development beyond the naupliar stages.     

Wastewater treatment and public health in Nunavut: a microbial risk assessment framework for the Canadian Arctic

Wastewater management in Canadian Arctic communities is influenced by several geographical factors including climate, remoteness, population size, and local food-harvesting practices. Most communities use trucked collection services and basic treatment systems, which are capable of only low-level pathogen removal. These systems are typically reliant solely on natural environmental processes for treatment and make use of existing lagoons, wetlands, and bays. They are operated in a manner such that partially treated wastewater still containing potentially hazardous microorganisms is released into the terrestrial and aquatic environment at random times. Northern communities rely heavily on their local surroundings as a source of food, drinking water, and recreation, thus creating the possibility of human exposure to wastewater effluent. Human exposure to microbial hazards present in municipal wastewater can lead to acute gastrointestinal illness or more severe disease. Although estimating the actual disease burdens associated with wastewater exposures in Arctic communities is challenging, waterborne- and sanitation-related illness is believed to be comparatively higher than in other parts of Canada. This review offers a conceptual framework and evaluation of current knowledge to enable the first microbial risk assessment of exposure scenarios associated with food-harvesting and recreational activities in Arctic communities, where simplified wastewater systems are being operated.     

Ecotoxicological Classification of the Berlin River System Using Bioassays in Respect to the European Water Framework Directive

Bioassays as well as biochemical responses (biomarkers) in ecosystems due to environmental stress provide us with signals (environmentally signalling) of potential damage in the environment. If these responses are perceived in this early stage in ecosystems, the eventual damage can be prevented. Once ecosystem damage has occurred, the remedial action processes for recovery could be expensive and pose certain logistical problems. Ideally, “early warning signals” in ecosystems using sensing systems of biochemical responses (biomarkers) would not only tell us the initial levels of damage, but these signals will also provide us with answers by the development of control strategies and precautionary measures in respect to the European Water Framework Directive (WFD). Clear technical guidelines or technical specifications on monitoring are necessary to establish and characterise reference conditions for use in an ecological status classification system for surface water bodies. For the Ecotoxicological Risk Assessment (ERA) of endocrine effects we used an approach of the exposure – dose – response concept. Based on the “Ecototoxicological Classification System of Sediments” that uses pT-values to classify effects in different river systems, we transferred the bio-monitoring data to the five-level ecological system of the WFD. To understand the complexity of the structure of populations and processes behind the health of populations, communities and ecosystems an ERA should establish links between natural factors, chemicals, and biological responses so as to assess causality. So, our ecological monitoring assessment has incorporated exposure & effects data.     

Identifying the European Fossil Fuel Plumes in the Atmosphere Over the Northeast Atlantic Region Through Isotopic Observations and Numerical Modelling

As part of the Danish NEAREX project the origin and variability of anthropogenic atmospheric CO₂ over the Northeast Atlantic Region (NEAR) has been studied. The project consisted of a combination of experimental and modelling activities. Local volunteers operated CO₂ sampling stations, built at University of Copenhagen, for ¹⁴C analysis at four locations (East Denmark, Shetland Isles, Faroe Isles and Iceland). The samples were only collected during winter periods of south-easterly winds in an attempt to trace air enriched in fossil-fuel derived CO₂ due to combustion of fossil fuels within European countries. In order to study the transport and concentration fields over the region in detail, a three-dimensional Eulerian hemispheric air pollution model has been extended to include the main anthropogenic sources for atmospheric CO₂. During the project period (1998–2001) only a few episodes of transport from Central Europe towards NEAR arose, which makes the data set for the evaluation of the method sparse. The analysed samples indicate that the signal for fossil CO₂, as expected, is largest (up to 3.7±0.4% fossil CO₂) at the Danish location closest to the European emissions areas and much weaker (up to ∼1.5±0.6% fossil CO₂) at the most remote location. As the anthropogenic signal is weak in the clean atmosphere over NEAR these numbers will, however, be very sensitive to the assumed background ¹⁴CO₂ activity and the precision of the measurements. The model simulations include the interplay between the driving processes from the emission into the boundary layer and the following horizontal/vertical mixing and atmospheric transport and are used to analyse the meteorological conditions leading to the observed events of high fossil CO₂ over NEAR. This information about the history of the air masses is essential if an observed signal is to be utilised for identifying and quantifying sources for fossil CO₂.     

Polychlorinated biphenyls, organochlorine pesticides and polycyclic aromatic hydrocarbons in a one-off global survey of bivalves

During the Danish Galathea 3 expedition, bivalve samples were collected at the Faroe Islands, Greenland, Ghana, South Africa, Australia, Solomon Islands, New Zealand, Chile, US Virgin Islands, Boston, Newfoundland and Shetland Islands and analysed for organochlorines and PAHs. Concentration differences of up to three orders of magnitude were observed, with the highest concentrations at Boston harbour (SPCB 338 ng g(-1) dw, ΣSPAH 5966 ng g(-1) dw) and the Sydney estuary (ΣSPCB 282 ng g(-1) dw, SPAH 1453 ng g(-1) dw). Local impacts were also found for the Greenland capital Nuuk in terms of PCB and PAH levels, while other Greenland samples came closest to representing PAH background levels. Several locations had undetectable organochlorine levels, including Hobart and Chile, which had the lowest SPAH concentrations (<200 ng g(-1) dw). It was possible to group the stations according to their pyrogenic/petrogenic influence using Principal Component Analyses, and indications of petroleum sources were found at Nuuk.     

Design and characterization of a two-stage human subject exposure chamber

A human subject exposure chamber, designed to hold six to eight subjects, coupled to an approximately 30-m3 Teflon reaction bag was designed and built to provide exposures that mimic the production and photochemical oxidation of atmospheric pollutants resulting from the combustion of coal or wood from a stove. The combustion products are introduced into the Teflon bag under atmospheric conditions. Photochemical oxidation of this mixture is accomplished by exposure to tropospheric sun-like radiation from an array of ultraviolet and black lamps. The aerosol in the Teflon reaction bag is then transferred into the exposure room to maintain a constant, lower exposure level. Continuous and semicontinuous monitoring of the gas and particulate matter (PM) pollution in the exposure room and the reaction bag is accomplished using a suite of instruments. This suite of instruments allows for the measurement of the concentrations of total and nonvolatile PM, nitric oxide, nitrogen dioxide, carbon monoxide, carbon dioxide, and ozone. The concentration of the particles was monitored by an R&P tapered element oscillating microbalance monitor. The chemical composition of the PM and its morphological characterization is accomplished by collecting samples in filter packs and conducting ion chromatography, elemental X-ray fluorescence, and scanning electron microscopy analyses. The concentration and composition of emissions from combustion of wood and coal is described. The results of this study suggest that although the bulk compositions of particulate emissions from the combustion of coal or wood in a stove have many similarities, the wood smoke aerosol is photochemically reactive, whereas the coal smoke aerosol is not.     

Characterization of odor released during handling of swine slurry: Part II. Effect of production type,storage and physicochemical characteristics of the slurry

The quality of rural life can be affected by offensive odors released from animal buildings and storage units. The objectives of this study were to compare the concentrations of odor and odorants above different types of stirred swine slurry to analyze the relationships between concentrations of odor (and odorants) and physicochemical characteristics of the slurry (i.e. pH, temperature, dry matter, volatile solids, and concentration of 22 chemical compounds); and to propose predictive models for the odor concentration (OC) based on these physicochemical characteristics (solely and in combination with concentrations of specific odorants in the air above the slurries). The study comprised data on concentrations of odor and odorants in the air above slurry samples (fresh and/or stored) collected from production units with farrowing sows, finishing swines, or weaning pigs at eight swine operations (N = 48). OC measured in the air above stirred swine slurry samples were not significantly different among production types or storage times. The physicochemical characteristics of the slurries were not useful for predicting OC or concentrations of hydrogen sulfide (or organic sulfides) above the slurry, but were related to concentrations of other emitted gases such as phenols and indoles (r² = 0.65–0.79, p <0.05), ammonia (r² = 0.86, p < 0.05) and carboxylic acids (r² = 0.23–0.59, p <0.05). There was good precision of predictive models of OC based on selected slurry characteristics (i.e. pH, dry matter, nitrogen content, sulfur content or concentrations of individual aromatic compounds and carboxylic acids) together with concentrations of specific odorants in the air (e.g. hydrogen sulfide) (r² between 0.70 and 0.92). This study suggests that predictive models could be useful for evaluating odor nuisance potentials of swine slurry during handling.     

Fate and antibacterial potency of anticoccidial drugs and their main abiotic degradation products

The antibacterial potency of eight anticoccidial drugs was tested in a soil bacteria bioassay (pour plate method), EC₅₀-values between 2.4 and 19.6 μM were obtained; however, one compound, nicarbazin exhibited an EC₅₀-value above the maximum tested concentration (21 μM, 9.1 mg L⁻¹). The potency of mixtures of two of the compounds, narasin and nicarbazin, was synergistic (more than additive) with 10-fold greater antibacterial potency of the mixture than can be explained by their individual EC₅₀-values. The influence of pH, temperature, oxygen concentration and light on the transformation of robenidine and salinomycin was investigated. Robenidine was transformed by photolysis (DT₅₀ of 4.1 days) and was unstable at low pH (DT₅₀ of approximately 4 days); salinomycin was merely transformed at low pH, the latter into an unknown number of products. The antibacterial potency of the mixtures of transformation products of robenidine after photolysis and at low pH was comparable with that of the parent compound. Finally five photo-transformation products of robenidine were structural elucidated by accurate mass measurements, i-FIT values (isotopic pattern fit) and MS/MS fragmentation patterns.     

Adsorption of mono- and di-butyltin by a wheat charcoal: pH effects and modeling

Understanding adsorption processes of butyltins (BTs) such as monobutyltin (MBT) and dibutyltin (DBT) by black carbons is important for the evaluation of BT exposure risks to organisms and humans. However, relevant knowledge is scarce. In this study, the acidity constants pK_a,1 = 2.3, pK_a,2 = 3.5 and pK_a,3 = 5.9 for MBT and pK_a,1 = 3.0 and pK_a,2 = 5.1 for DBT are estimated via potentiometric titration. Additionally, adsorption isotherms of BTs to a wheat charcoal were determined. The adsorption behavior was observed to be pH-dependent due to BT speciation and the pH-dependent surface charge of the charcoal. MBT adsorption to the charcoal decreases with increasing pH from 4 to 8, while the highest adsorption occurs at pH 6 for DBT. Adsorption of the BTs is successfully described in the pH range of 3-10 by using a newly developed pH-dependent Dual Langmuir model. The model has the potential to predict the interaction of BT species with charcoal, which can contribute to the risk assessments of BTs in the environment.