Comparing growth development of Myriophyllum spp. in laboratory and field experiments for ecotoxicological testing

Background, goals and scope: Risk assessment of herbicides and the evaluation of contaminated sediments based on algae and the macrophyte Lemna sp. alone may underestimate the potential hazard of certain compounds. Therefore, various test systems with Myriophyllum spp. have been developed recently to assess the phytotoxicity in surface waters and natural sediments. In the present study, experiments investigating the growth development of Myriophyllum spp. were performed in the laboratory under defined conditions and in mesocosms under environmentally realistic exposure conditions to evaluate the suitability of these species as potential standard test organisms in ecotoxicological testing. This study provides data on the endpoints biomass, plant length and root development. Materials and methods: Six independent experiments were performed to investigate the plant development of Myriophyllum spp. under control conditions. The main difference in the experiments was the complexity of the test systems ranging from simple laboratory experiments to complex outdoor mesocosm studies. At the start of each experiment, uniform cuttings of Myriophyllum spp. were placed in vessels with or without sediments to reduce variability between replicates. The endpoints considered in this investigation were biomass (fresh weight of the whole plant), length of the main shoot, length of the side shoots, total length of the plant (calculated from the length of the main and side shoots) and root formation. Root to shoot ratios were calculated as a further measure for plant development. Relative growth rates (RGR) based on plant length (RGLR) and on biomass (RGBR) were calculated. Results: Despite the various experimental conditions, comparable growth was obtained in all test systems and the variability of endpoints, such as total length and biomass of plants, was low. It was observed that the RGR of M. spicatum in the simple laboratory test system with sediment were comparable to growth data obtained for M. verticillatum and M. spicatum grown in indoor and outdoor mesocosms, thus indicating that Myriophyllum growth tends to increase by the addition of sediment. High variability was determined for the endpoints length of the side shoots, total root length and biomass of roots. Discussion: One challenge for a test design to investigate phytotoxicity on aquatic plants is to obtain good growth of the plants. From the results, it can be concluded that the experimental conditions in the various test systems were suitable to study the plant development of Myriophyllum spp. because obtained growth rates were comparable between laboratory and field investigations. Another challenge for developing a plant biotest system is the definition of sensitive endpoints. Low variability is preferred to detect minor effects of chemicals or polluted sediments on plant development. In our studies, the variability of the endpoints biomass and total length of plant was low and, therefore, they have much potential as endpoints for assessing toxicity. Conclusions: The methodologies presented in this study have applications within the risk assessment for aquatic plants and have the advantage of assessing effects taking into account the relevant exposure pathways via water and/or sediment for compounds under investigation. Recommendations and perspectives: Setting safe quality criteria for surface water and sediments is one of the challenges authorities are facing today. Myriophyllum spp. is recommended as suitable test species to investigate phytotoxicity in surface water and sediments. These results, thus, might serve as a basis for the compilation of a new harmonised guideline for ecotoxicological testing with aquatic macrophyte

РОЗВИТОК СИСТЕМИ ПОЧАТКОВОЇ ТА СЕРЕДНЬОЇ ОСВІТИ У МЕНОНІТСЬКИХ КОЛОНІЯХ КАТЕРИНОСЛАВСЬКОГО ПОВІТУ НАПРИКІНЦІ XIX – НА ПОЧАТКУ XX СТ.

Проблеми формування системи початкової освіти постійно знаходи-лись у фокусі громадської уваги менонітського соціуму, який намагався шля-хом надзвичайної концентрації інтелектуальних, фінансових та господарчих зусиль сприяти її всебічному становленню та розвитку. Ґенеза менонітсько-го віровчення, темпи та масштаб його поширення серед населення північ-них регіонів Західної Європи були об'єктивно зумовлені наявністю у пред-ставників даного релігійного руху елементарних освітянських навичок (вміння читати та писати), які були необхідні для раціонального тлумачен-ня біблійних та релігійних текстів. Поява розгалуженої освітянської системи в громадах менонітів була детермінована специфікою віровчення спільноти, її нагальними релігійними, церковними та громадськими потребами. Зазначимо, що меноніти розглядали шкільництво як один із засобів набуття «освічено-го благочестя»

Numerical simulation of heat transfer in a large room with a working gas infrared emitter

The article presents a new approach to determining the main characteristics of the thermal regime in the buildings and structures heated by the gas infrared emitters, based on the analysis of convective heat transfer in the air and thermal conductivity in the enclosing structures. The authors have considered a mathematical model of turbulent heat transfer in the framework of the standard k-e model under radiant heating conditions. The simulation was carried out for a large room with an approximation to the real operating conditions of an industrial facility. The options for heating an empty room and the room with an object were considered

Методические указания к выполнению индивидуальных заданий практикума по дисциплине «Энергетический потенциал природных возобновляемых энергоресурсов и эффективность его преобразования в электроэнергию»

В методических указаниях рассмотрены вопросы оценки энергетического потенциала природных возобновляемых энергоресурсов: ветра, солнечного излучения и потоков воды и эффективности их преобразования в электроэнергию. Пособие предназначено для студентов дневного обучения по направлению13.04.02 «Электроэнергетика и электротехника» по профилям магистерской подготовки «Возобновляемые источники энергии» и «Оптимизация развивающихся систем электроснабжения»

Ecotoxicological testing of sediments and dredged material: an overlooked opportunity?

Purpose: Basing decisions for the management of contaminated sediments on ecotoxicological data is still often met with skepticism by European stakeholders. These concerns are discussed as they pertain to bioassays to show how ecotoxicological data may provide added value for the sustainable management of sediment in aquatic systems.Materials and methods: Five “concerns” are selected that are often raised by stakeholders. The ecotoxicological practice is discussed in light of the knowledge gained in recent decades and compared with chemical sediment analysis and chemical data.Results and discussion: Common assumptions such as a higher uncertainty of biotest results for sediments compared to chemical analyses are not supported by interlaboratory comparisons. Some confusion also arises, because the meaning of biotest data is often misunderstood, questioning their significance in light of a limited number of organisms and altered test conditions in the lab. Because biotest results describe a sediment property, they should not be directly equated with an impact upon the biological community. To identify a hazard, however, the possibility of false-negative results due to the presence of contaminants that are not analyzed but are toxic is lower.Conclusions: The cost of increased investment in ecotoxicological tests is, in our view, small compared with that of making false-negative assessments of sediment/dredged material that can ultimately have long-term environmental costs. As such, we conclude that ecotoxicological testing is an opportunity for sediment management decision-making that warrants more attention and confidence in Europe.Hochschule für Angewandte Wissenschaften Hamburg (HAW Hamburg) (3369