Получение желаемых передаточных функций импульсных систем автоматического управления

Рассмотрена задача получения желаемых передаточных функций импульсных систем автоматического управления. Предложен способ синтеза передаточных функций низкого порядка по прямым показателям качества, обеспечивающий конечное время переходного процесса

Equilibrium sampling of polychlorinated biphenyls in River Elbe sediments – Linking bioaccumulation in fish to sediment contamination

AbstractEquilibrium sampling can be applied to measure freely dissolved concentrations (cfree) of hydrophobic organic chemicals (HOCs) that are considered effective concentrations for diffusive uptake and partitioning. It can also yield concentrations in lipids at thermodynamic equilibrium with the sediment (clip⇌sed) by multiplying concentrations in the equilibrium sampling polymer with lipid to polymer partition coefficients. We have applied silicone coated glass jars for equilibrium sampling of seven ‘indicator’ polychlorinated biphenyls (PCBs) in sediment samples from ten locations along the River Elbe to measure cfree of PCBs and their clip⇌sed. For three sites, we then related clip⇌sed to lipid-normalized PCB concentrations (cbio,lip) that were determined independently by the German Environmental Specimen Bank in common bream, a fish species living in close contact with the sediment: (1) In all cases, cbio,lip were below clip⇌sed, (2) there was proportionality between the two parameters with high R2 values (0.92–1.00) and (3) the slopes of the linear regressions were very similar between the three stations (0.297; 0.327; 0.390). These results confirm the close link between PCB bioaccumulation and the thermodynamic potential of sediment-associated HOCs for partitioning into lipids. This novel approach gives clearer and more consistent results compared to conventional approaches that are based on total concentrations in sediment and biota-sediment accumulation factors. We propose to apply equilibrium sampling for determining bioavailability and bioaccumulation potential of HOCs, since this technique can provide a thermodynamic basis for the risk assessment and management of contaminated sediments

Equilibrium sampling of HOCs in sediments and suspended particulate matter of the Elbe River

Abstract Background Chemical quality of sediment and suspended particulate matter (SPM) is usually assessed by total chemical concentrations (C total). However, the freely dissolved concentration (C free) is the ecologically more relevant parameter for bioavailability, diffusion and bioaccumulation. In recent studies, equilibrium sampling has been applied to determine C free of hydrophobic organic contaminants (HOCs) in the sediment pore water, whereas such data are missing for SPM. We applied solid-phase micro-extraction to measure and compare C free of PAHs and PCBs in pore water of sediments and SPM sampled along the German part of the river Elbe. Moreover, site-specific distribution ratios were evaluated and C bio,lipid was predicted using C free. Results C free of PAHs remained largely constant while C free of PCBs varied along the Elbe River. The highest C total of PCBs and PAHs were found at Prossen (km 13) and Meißen (km 96). PCB C total even exceeded the environmental quality standard for sediment and SPM in Prossen. Site-specific distribution ratios (K D) revealed a stronger sorption for PAHs compared to PCBs, indicating a higher availability of PCBs. Equilibrium partitioning concentrations in lipids (C lip↔sed) showed a high correlation with actually measured lipid-normalised concentrations (C bio,lipid) in bream. This indicates that PCB bioaccumulation in this benthic fish species is closely linked to the sediment contamination. Conclusions In rivers, SPM functions as a transportation vehicle for HOCs along the stream until it eventually deposits to the sediment. This study demonstrates that due to weaker sorption of PAHs and PCBs to the SPM this matrix poses a higher risk to the aquatic environment compared to the sediment. The prediction of C bio,lipid of PCBs was correct and shows that solid-phase micro-extraction is highly suited to predict lipid concentration, and thus a valuable tool for risk-assessment or sediment management

MOESM1 of Equilibrium sampling of HOCs in sediments and suspended particulate matter of the Elbe River

Additional file 1: Table S1. Biometric data and information on the tissue treatment of the sampled fish. Table S2. Sampling stations in the German part of the River Elbe including the station name, river km, matrix (sediment or suspended particulate matter (SPM)), the geographical position (latitude, longitude) and the sampler. Sediment samples were collected in July and SPM in September 2014. Table S3. Ctotal of seven PCBs in sediment samples from the River Elbe in µg kg−1 (dw). Table S4. Ctotal of PAHs in sediment samples from the River Elbe in µg kg−1 (dw). Table S5. Ctotal of seven PCBs in SPM samples from the River Elbe in µg kg−1 (dw). Table S6. Ctotal of PAHs in SPM samples from the River Elbe in µg kg−1 (dw). Table S7. Cfree of PCBs in sediment samples from the River Elbe in pg L−1. Table S8. Cfree of PAHs in sediment samples from the River Elbe in pg L−1. Table S9. Cfree of PCBs in SPM samples from the River Elbe in pg L−1. Table S10. Cfree of PAHs in SPM samples from the River Elbe in pg L−1

A comparative approach using ecotoxicological methods from single-species bioassays to model ecosystems

Hägerbäumer A, Höss S, Ristau K, et al. A comparative approach using ecotoxicological methods from single-species bioassays to model ecosystems. Environmental Toxicology and Chemistry. 2016;35(12):2987-2997

Passive sampler phases for pesticides: evaluation of AttractSPE™ SDB-RPS and HLB versus Empore™ SDB-RPS

In this study, three different passive sampling receiving phases were evaluated, with a main focus on the comparability of established styrene-divinylbenzene reversed phase sulfonated (SDB-RPS) sampling phase from Empore™ (E-RPS) and novel AttractSPE™ (A-RPS). Furthermore, AttractSPE™ hydrophilic-lipophilic balance (HLB) disks were tested. To support sampling phase selection for ongoing monitoring needs, it is important to have information on the characteristics of alternative phases. Three sets of passive samplers (days 1-7, days 8-14, and days 1-14) were exposed to a continuously exchanged mixture of creek and rainwater in a stream channel system under controlled conditions. The system was spiked with nine pesticides in two peak scenarios, with log