| 1. |
- Andersson, Patrik, et al.
(författare)
-
Ultraviolet absorption characteristics and calculated semi-empirical parameters as chemical descriptors in multivariate modelling of polychlorinated biphenyls
- 1996
-
Ingår i: Journal of Chemometrics. - 0886-9383 .- 1099-128X. ; 10:2, s. 171-185
-
Tidskriftsartikel (refereegranskat)abstract
- The structural variation within the polychlorinated biphenyls (PCBs) was characterized by using principal component analysis (PCA). A multivariate model was evolved from 52 physicochemical descriptors including measured ultraviolet (UV) absorption spectra, calculated semiempirical parameters (AM1) and properties captured from the literature. Parameters calculated by using the AM1-Hamiltonian were e.g. heat of formation, dipole moments, ionization potential and the barrier of internal rotation. The UV spectra were measured and digitized in the range 200-300 nm. The multivariate model revealed that most of the information within the set of physicochemical parameters was related to molecular size. Descriptors depending on size were e.g. GC retention times, partition coefficients and a subset of semiempirically derived energy terms. Important also were parameters reflecting differences in substitution patterns and related to electronic and steric properties, such as UV absorption in the wavelength region 245-300 nm, the barrier of internal rotation and the ionization potential. The developed model describes the large variation in physicochemical characteristics within the PCBs. The importance of a broad chemical characterization is illustrated by a quantitative structure-activity relationship (QSAR) for the potency of inhibition of intercellular communication for 27 structurally diverse tetra- to heptachlorinated PCBs.
|
|
| 2. |
- Buser, H-R, et al.
(författare)
-
Discrimination and thermal degradation of toxaphene compounds in capillary gas chromatography when using split/splitless and on-column injection
- 2000
-
Ingår i: Chemosphere. ; 41:4, s. 473-9
-
Tidskriftsartikel (refereegranskat)abstract
- Technical toxaphene and a 22-component Reference Mixture were analyzed using capillary gas chromatography with split/splitless injection (SSL) and on-column injection (OC). In both techniques, electron-capture, negative ionization mass spectrometry (ECNI-MS) was used for detection of chlorobornanes, chlorocamphenes and related compounds. Significant discrimination of highly chlorinated congeners was observed as a result of incomplete transfer of these compounds from the vaporizer to the analytical column when using SSL. This resulted in a much lower response for nona- and decachloro congeners than when using OC. In addition, several toxaphene components, especially the chlorobornanes with gem dichloro substitution on the six-member carbon ring, undergo thermal degradation when using SSL. Some of these congeners are major components of technical toxaphene, but generally are not present, except at low concentrations, in environmental and biological samples. Therefore, technical toxaphene may be discriminated and/or degraded differently than toxaphene compounds in environmental samples when using SSL. This results in significant bias of the quantitative data when using the technical material as a reference. OC suffers much less from these deficiencies and, therefore, is a preferable technique for toxaphene analysis.
|
|
| 3. |
- Buser, Hans-Rudolf, et al.
(författare)
-
Rapid anaerobic degradation of toxaphene in sewage sludge
- 2000
-
Ingår i: Chemosphere. ; 40:9-11, s. 1213-20
-
Tidskriftsartikel (refereegranskat)abstract
- We studied the degradation of technical toxaphene in anaerobic sewage sludge from a municipal waste water treatment plant. Chlorobornanes, chlorocamphenes and related compounds were rapidly degraded, with degradation rates in the order of decachloro>nonachloro>octochloro>heptachloro ≈ hexachloro compounds. The half-lives of individual congeners ranged from <1 day to several days. We also studied the degradation of technical toxaphene in previously sterilized sludge (control), and found it was slower than in the anaerobic sludge. The chlorobornanes that degraded most rapidly in the non-sterilized anaerobic sludge were those with gem chloro substitution on the 6-member carbon-ring, including the toxic congeners, Toxicant A and B. Non-gem chloro substituted congeners, like the biologically persistent P26 and P50, also degraded, but less rapidly. Toxaphene degradation in sewage sludge proceeded primarily via reductive dechlorination, leading to HxSed, HpSed, TC2 and other persistent metabolites. Enantioselective determinations indicated little, if any, enantioselectivity in the formation and/or degradation of these compounds. The isomer and enantiomer profiles of the hexa-, hepta-, and octachlorobornanes are similar to those observed in sediment from the Baltic Sea, suggesting that technical toxaphene is the source of these compounds and that its composition was changed via similar anaerobic degradation pathways.
|
|
| 4. |
-
Chlorinated dioxins and dibenzofurans in perspective
- 2018
-
Samlingsverk (redaktörskap) (refereegranskat)abstract
- This volume was developed from the proceedings of a symposium held in Miami Beach, at the 189th National Meeting of the American Chemical Society.It is the result of the combined efforts of many experts whose efforts have advanced our knowledge of the production, analysis, distribution, effects and control of chlorinated dioxins, dibenzofurans and related compounds.This is the third in a series of publications originating from current technology presented at national meetings of the American Chemical Society. Using this forum as a catalyst, researchers from all over the world came together to present and discuss their data and plan future work in this rapidly developing and sometimes highly emotional technical area.
|
|
| 5. |
- Duffy, J. Emmett, et al.
(författare)
-
Toward a Coordinated Global Observing System for Seagrasses and Marine Macroalgae
- 2019
-
Ingår i: Frontiers in Marine Science. - : Frontiers Media S.A.. - 2296-7745. ; 6
-
Forskningsöversikt (refereegranskat)abstract
- In coastal waters around the world, the dominant primary producers are benthic macrophytes, including seagrasses and macroalgae, that provide habitat structure and food for diverse and abundant biological communities and drive ecosystem processes. Seagrass meadows and macroalgal forests play key roles for coastal societies, contributing to fishery yields, storm protection, biogeochemical cycling and storage, and important cultural values. These socio-economically valuable services are threatened worldwide by human activities, with substantial areas of seagrass and macroalgal forests lost over the last half-century. Tracking the status and trends in marine macrophyte cover and quality is an emerging priority for ocean and coastal management, but doing so has been challenged by limited coordination across the numerous efforts to monitor macrophytes, which vary widely in goals, methodologies, scales, capacity, governance approaches, and data availability. Here, we present a consensus assessment and recommendations on the current state of and opportunities for advancing global marine macrophyte observations, integrating contributions from a community of researchers with broad geographic and disciplinary expertise. With the increasing scale of human impacts, the time is ripe to harmonize marine macrophyte observations by building on existing networks and identifying a core set of common metrics and approaches in sampling design, field measurements, governance, capacity building, and data management. We recommend a tiered observation system, with improvement of remote sensing and remote underwater imaging to expand capacity to capture broad-scale extent at intervals of several years, coordinated with strati fied in situ sampling annually to characterize the key variables of cover and taxonomic or functional group composition, and to provide ground-truth. A robust networked system of macrophyte observations will be facilitated by establishing best practices, including standard protocols, documentation, and sharing of resources at all stages of work flow, and secure archiving of open-access data. Because such a network is necessarily distributed, sustaining it depends on close engagement of local stakeholders and focusing on building and long-term maintenance of local capacity, particularly in the developing world. Realizing these recommendations will producemore effective, efficient, and responsive observing, a more accurate global picture of change in vegetated coastal systems, and stronger international capacity for sustaining observations.
|
|
| 6. |
- Falandysz, Jerzy, et al.
(författare)
-
Chlorinated Cyclodiene Pesticide Residues in Blue Mussel, Crab, and Fish in the Gulf of Gdask, Baltic Sea
- 2001
-
Ingår i: Environmental Science & Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 35:21, s. 4163-9
-
Tidskriftsartikel (refereegranskat)abstract
- Chlordane components (CHLs) and their metabolites (heptachlor, cis-heptachlor epoxide, U82, MC4, trans-chlordane, MC5, cis-chlordane, MC7, oxychlordane, MC6,and trans- and cis-nonachlor) and aldrin, dieldrin, endrin, isodrin, endosulfan 1, endosulfan 2, and mirex were quantified in the soft tissues of blue mussel, a whole crab, and whole fishes collected from the spatially different sites in the Gulf of Gdask. Six to twelve chlordane compounds and metabolites and dieldrin were detected in all organisms examined while aldrin, endrin, isodrin, endosulfans 1 and 2, and mirex were not found above the detection limit of the method. The lipid weight based concentrations in Baltic biota were relatively small and ranged from 12 to 150 and 7.6-77 ng/g, while between 0.16 and 6.8 and 0.10-6.6 ng/g in fresh tissue, respectively. The profile (%) of chlordane compounds was very similar between various fish species with trans-nonachlor (28 ± 17), cis-chlordane (23 ± 18), oxychlordane (13 ± 7), and heptachlor epoxide (11 ± 5) as major constituents and was totally different in crab with oxychlordne as the most dominating (>65%) compound. Blue mussel, lamprey, and three-spined stickleback exhibited a smallest ability to metabolize CHLs, and such fishes as cod, lesser sand-eel, sand-eel, pikeperch, perch, round goby, flounder, and herring showed a slightly better ability, while crab was able to effectively metabolize most of CHL compounds except trans-nonachlor. A value of the quotient of the trans-nonachlor to cis-chlordane concentrations (N/C quotient) was 1.0 in blue mussel, 3.1 in crab, and between 0.9 and 1.8 in fish. Both the small concentrations of CHLs in all organisms and the values of N/C quotients close to 1 imply on a long-range aerial transport through movement of the air masses from the remote regions of the northern hemisphere as a main source of this pesticide in the Gulf of Gdask. The interdependences between the CHL profiles for various fish species and between different sampling sites were examined using the principal component analysis (PCA) method. Applying the PCA model the first four significant components explained 90% (43% + 23% + 15% + 8%) of the total variance in the data matrix.
|
|
| 7. |
- Falandysz, J, et al.
(författare)
-
Multivariate analysis of the bioaccumulation of polychlorinated biphenyls (PCBs) in the marine pelagic food web from the southern part of the Baltic Sea, Poland
- 2002
-
Ingår i: Journal of Environmental Monitoring. - : Royal Society of Chemistry (RSC). - 1464-0325 .- 1464-0333. ; 4:6, s. 929-941
-
Tidskriftsartikel (refereegranskat)abstract
- The concentration, pattern, bioaccumulation and biomagnification features of many chlorobiphenyl congeners, including non- and mono-ortho chlorine substituted members have been determined in a pelagic food chain including mixed phyto- and zooplankton-1 herring (Clupea harengus), harbour porpoise (Phocoena phocoena) and black cormorants (Phalacrocorax carbo sinensis) collected from the southern part of the Baltic, Proper. TCDD (tetrachlorodibenzo-p-dioxin) toxic equivalents (TEQs) in plankton, herring, harbour porpoise and cormorants. were 0.42, 5.3, 79 and 2700 pg g(-1) lipid weight, respectively. Concentrations of total, polychlorinated biphehyls (PCBs) in plankton, herring harbour porpoise and cormorants were 1.9, 120, 8700 and 2100 ng g(-1) wet weight (210, 1300, 10000 and 42000 ng g(-1) lipid weight) respectively. Herring, harbour porpoise and black cormorant apparently bioaccumulate many PCBs found in their food, and the values of the bioaccumulation factor's (BAFs) for PCBs were approximately 10 in herring, 35 in harbour porpoise and up to 300 in breast muscle of, cormorants. Harbour porpoise clearly is able to metabolize. the most toxic, non-ortho PCBs (no. 77, 126 and 169) and a few mono-ortho PCBs (no. 114, 123 and 156), while all non- and mono-ortho PCBs are bioaccumulated by herring. Penta-, hexa- and hepta-CBs were the dominant homologue classes both in the muscle tissue and liver. PCB congeners nos. 201, 209, 172/192, 194 and 195 were characterized by the largest.. BAFs (between 100 and 300). Principal component analysis has been used to analyse the interdependences. and differences in the CB congener accumulation patterns between the, components of the investigated pelagic food web.
|
|
| 8. |
- Falandysz, J, et al.
(författare)
-
Polychlorinated biphenyls (PCBs) and their congener-specific accumulation in edible fish from the Gulf of Gdask, Baltic Sea
- 2002
-
Ingår i: Food Additives & Contaminants. - : Informa UK Limited. - 0265-203X. ; 19:8, s. 779-95
-
Tidskriftsartikel (refereegranskat)abstract
- Concentrations and composition profiles of polychlorinated biphenyls (PCBs) were investigated in composite samples of 10 species of edible fish from the Gulf of Gda sk, in the southern part of the Baltic Sea, Poland, to understand the status of contamination and possible human exposure risk. Apart from the total PCBs, planar non-ortho (IUPAC nos 77, 126, 169) and mono-ortho (nos 105, 114, 118, 123, 156, 157, 167, 189) chlorobiphenyls were also quantified and their dioxin-like toxicity assessed. The absolute total PCB concentrations in fish ranged from 43 to 490 ng g-1 wet wt (910-11000 ng g-1 lipids), while of TCDD TEQs of planar members were from 0.15 to 3.1 pg g-1 wet wt (8.1-81 pg g-1 lipids). The penta- and hexa-CBs usually comprised 70-80% of the total PCBs and were followed by hepta-, tetra- and tri-CBs, and for a specific site tri- and tetra-CBs comprised as much as 22%. Among the individual CB congeners, nos 118, 153 (+132) and 138 (+160 +163 +164) were the most abundant, while no. 110 comprised between 6.8 and 9.3% of the total PCBs in some species. Principal component analysis (PCA) was applied to examine the interdependences among CB congeners in the factor space. The PCA model and cluster analyses were further used to examine site- and species-specific differences and similarities of PCB composition, and the results are discussed. An assessed daily intake rate of TCDD TEQ of planar PCBs with the fishmeal of the Gulf of Gda sk in the 1990s was between 78 and 96 pg per capita or between 1.3 and 1.6 pg kg-1 body weight.
|
|
| 9. |
- Falandysz, J, et al.
(författare)
-
Polychlorinated biphenyls (PCBs) in black cormorants breeding at the coast of the Gulf of Gdansk, Baltic Sea
- 2003
-
Ingår i: Fresenius Environmental Bulletin: Special Issue: Sp. Iss. SI. ; 12:2, s. 127-42
-
Tidskriftsartikel (refereegranskat)abstract
- Concentrations, composition profiles and biomagnification of polychlorinated biphenyls non-ortho (IUPAC nos 77, 126, 169), mono-ortho (105, 114, 118, 123, 156, 157, 167, 189) and total PCBs were investigated in black cormorants (Phalacrocorax carbo sinensis) breeding at the coast of the Gulf of Gdansk, Baltic Sea. Total PCB concentrations in birds were in the range from 750 to 5200 ng/g wet wt ( from 19000 to 110000 ng/g lipid wt) in the breast muscles and from 440 to 4200 ng/g, wet wt (13000 to 69000 ng/g lipid wt) in liver. Penta-, hexa and hepta-CBs were dominating homologue classes both in the muscle tissue and liver. PCB congeners nos. 201, 209, 172/192. 194 and 195 were characterized by the greatest bioaccumulation factors (between 100 and 300). Principal Component Analysis (PCA) has been used to analyse accumulation pattern and interdependences among CB congeners.
|
|
| 10. |
|
|
