Biomedical subjects

Orjan Gustafsson

Publications and source records attributed to Orjan Gustafsson.

33 records · Page 2Linked to original sources

PubMed2004

Effect of sorbate planarity on environmental black carbon sorption.

Soot and charcoal, collectively termed "black carbon" or BC, can exhibit extremely strong sorption of many hydrophobic organic compounds. In order to include BC sorption in fate models, it is important to know BC nanopore surface areas. In addition, it is useful to know for which compounds BC sorption can be expected to be important. By nitrogen adsorption measurements at ultralow pressures on sediment that was strongly enriched in BC by HF treatment and/or chemothermal oxidation at 375 degrees C, we found that environmental BC has nanoporosity in the <4-10 A size range. The nanopore surface area (<50 A) of BC in Lake Ketelmeer (The Netherlands) sediment was approximately 58 m2/g. We measured sorption isotherms over a wide concentration interval for four compounds with the same Kow (10(46+/-0.1): planar anthracene (ANT), phenanthrene (PHE), and 4-chlorobiphenyl (4-PCB) along with nonplanar 2,2'-dichlorobiphenyl (2,2'-PCB). The environmental BC sorption coefficients of these iso-Kow compounds decreased in the order ANT > PHE approximately 4-PCB >> 2,2'-PCB and spanned a factor of 50-200, depending on concentration. Nonplanar 2,2'-PCB showed much more linear BC sorption (nF = 0.92) than the planar compounds (nF = 0.54-0.70). This shows that steric hindrance strongly attenuates BC-sorbate interactions for a nonplanar PCB. Thus, BC is more important for environmental sorption of planar compounds (>50% sorbed to BC in the nanogram per liter range) than for nonplanar ones (<10-20%). Using the measured BC nanopore surface area, a close agreement between modeled and measured BC sorption data could be found.

Adsorption↗

PubMed2004

Relations between environmental black carbon sorption and geochemical sorbent characteristics.

Pyrogenic carbon particles in sediments (soot and charcoal, collectively termed "black carbon" or BC) appear to be efficient sorbents of many hydrophobic organic compounds, so they may play an important role in the fate and toxicity of these substances. To properly model toxicant sorption behavior, it is important to (i) quantify the magnitude of the role of BC in sorption and (ii) elucidate which geochemical BC characteristics determine the strength of environmental BC sorption. Sorption isotherms of d10-phenanthrene (d10-PHE) were determined over a wide concentration range (0.0003-20 microg/L), for five sediments with widely varying characteristics. From the sorption isotherms, we determined Freundlich coefficients of environmental BC sorption, K(F,BCenv. These varied from 10(4.7) to 10(5.5). From the data, it could be deduced that BC was responsible for 49-85% of the total d10-PHE sorption at a concentration of 1 ng/L. At higher concentrations, the importance of BC for the sorption process diminished to <20% at 1 microg/L and 0-1% at 1 mg/L. There were no significant relationships between BC sorption strength and the tested geochemical BC characteristics [the fraction of small (<38 microm) BC particles, the BC resistance to high-temperature oxidation, the fraction of biomass-derived BC, the native polycyclic aromatic hydrocarbon and total organic carbon contents]. Because of the limited variation in BC sorption strength with widely varying BC characteristics, the presented BC sorption coefficients may putatively be used as generic starting points for environmental modeling purposes.

Adsorption↗

PubMed2004

Latitudinal fractionation of polychlorinated biphenyls in surface seawater along a 62 degrees N-89 degrees N transect from the southern Norwegian Sea to the North Pole area.

Surface seawater concentrations of PCBs, relative congener abundance, and possible effects of cold condensation were studied along a transect from the southern Norwegian Sea to the central Arctic Ocean (62 degrees N-89 degrees N). Large volume samples were collected from an ice breaker using a stainless steel surface seawater intake connected online to an ultra-clean laboratory. Concentrations of all studied PCB congeners, except for trichlorinated PCB 18, decreased with latitude. For instance, PCB 52 decreased from 470 fg L(-1) at 62 degrees N to 110 fg L(-1) at 89 degrees N and PCB 180 from 110 to 12 fg L(-1). Concentrations in the central Arctic Ocean were on the order of 10-100 fg L(-1) for the most abundant congeners. The relative contribution oftrichlorinated PCBs to the total PCB concentration increased with latitude, the tetrachlorinated contribution to the total PCBs did not show any correlation to latitude, and the relative contribution of heavier congeners decreased with latitude. This study establishes the occurrence at very low abundances of PCBs in seawater in the central Arctic Ocean and demonstrates a northward concentration decrease. The latitudinal shift in congener pattern is reflecting the relative propensity of the PCB congeners to undergo long-range transport in the Arctic and is consistent with their relative vapor pressures.

Air Movements↗

PubMed2004

Chlorine isotope analysis of submicromole organochlorine samples by sealed tube combustion and thermal ionization mass spectrometry.

Improved sensitivity in the analysis of stable chlorine isotopes of organochlorines (delta(37)Cl-OCl) has been established using sealed tube combustion in conjunction with thermal ionization mass spectrometry (TIMS). TIMS of chlorine isotopes was performed on <85 nmol of Cl with an achievable precision of <0.25 per thousand for pure inorganic chloride samples and 0.46 per thousand for chloride liberated from organochlorines (OCls). This makes possible significant reductions in the overall sample size requirement, as compared to the techniques of gas source stable isotope ratio mass spectrometry (SIRMS). Yields in excess of 99% were demonstrated in the dechlorination of <0.14 micromol 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT), and the overall yield, including purification of liberated chloride, was 86-97%. The accuracy of TIMS in the measurement of chlorine isotopes derived from OCls was confirmed by analysis of a DDT sample previously analyzed with SIRMS.(9) Using the described method for TIMS, the DDT sample gave a bulk chlorine isotope ratio of delta(37)Cl -4.42 +/- 0.46 per thousand (1sigma). The reported value from SIRMS analysis is -4.34 +/- 0.25 per thousand, indicating the conformity of the two methods.

Journal Article↗

PubMed2004

Particle-water partitioning of PCBs in the photic zone: a 25-month study in the open Baltic Sea.

From previous laboratory and field studies, it remains unclear whether partitioning of hydrophobic organic contaminants (HOCs) to phytoplankton from water is kinetically limited or may be treated as an equilibrium process. Here, we report on the partitioning of polychlorinated biphenyls (PCBs) to particulate organic carbon (POC), dominated by planktonic primary production, in the open Baltic Sea during a 25-month period. The organic carbon-normalized partition coefficient (Koc) was corrected for temperature, salinity, and sorption to filter-passing organic carbon. At all 21 sampling occasions, the log Koc-log Kow regression was significantly linear, despite a large variation in biogeochemical parameters such as POC concentration and composition, primary production, and phytoplankton species composition. These data strongly suggest that partitioning of PCBs to POC in temperate surface waters is equilibrated and therefore not kinetically limited by factors such as rapid phytoplankton growth rate or large cell size. The partitioning of PCBs to the POC was described throughout seasonal cycles by log Koc = 0.88 +/- 0.07 log Kow + 0.90 +/- 0.47 (95% confidence interval). The slope of the log Koc-log Kow regression for the single sampling occasions varied between 0.56 and 1.25, and there was a seasonal variation in the POC sorbent quality (e.g., log Koc for PCB 28 varied between 5.5 and 6.9; median 5.9). These variations reflect the variability in structural composition of the POC pool in such pelagic waters. Being able to predict particle-water partitioning of HOCs significantly reduces the required complexity of both food web uptake models and predictions of POC-mediated export of HOCs to the deep ocean.

Baltic States↗

PubMed2004

Sorption of phenanthrene to environmental black carbon in sediment with and without organic matter and native sorbates.

Strong sorption to soot- and charcoal-like material (collectively termed black carbon or BC) in soils and sediments is possibly the reason for recent observations of elevated geosorbent-water distribution ratios, slow desorption, limited uptake, and restricted bioremediation. We evaluated the role of environmental BC in the sorption of phenanthrene (PHE) to a polluted lake sediment from a Rhine River sedimentation area. Sorption isotherms were determined over a wide concentration range (0.0005-6 microg/ L) for the original sediment (with organic matter or OM, native sorbates, and BC), sediment from which we had stripped > 90% of the native sorbates (only OM and BC), and sediment combusted at 375 degrees C (only BC). The sorption isotherms of the original and stripped sediments were almost linear (Freundlich coefficient or n(F) > 0.9), whereas the isotherm of the BC remaining after the sediment combustion was highly nonlinear (n(F) = 0.54). At low concentrations (ng/L range), PHE sorption to BC in the combusted sediment was found to exceed the total PHE sorption in the original and stripped sediments. This implies that it may not be possible to use a BC-water sorption coefficient measured in combusted sediment to estimate total sorption to the original sediment. This "intrinsic" BC-water sorption coefficient after combustion was calculated to be 9 times larger than the "environmental" one in the untreated sediment. Competition between the added PHE and the native PAHs and/or OM may explain this difference. It appears that, at low aqueous PHE concentrations (ng/L and below), BC is the most important geosorbent constituent with respect to sorption. At higher concentrations (microg/L), BC sorption sites become saturated and BC sorption is overwhelmed by sorption to the other OM constituents. Because sorption is a central process affecting contaminant behavior and ecotoxicity, understanding this process can strongly contribute to risk assessment and fate modeling.

Adsorption↗

PubMed2004

Polycyclic aromatic hydrocarbons, black carbon, and molecular markers in soils of Switzerland.

Polycyclic aromatic hydrocarbons (PAH) were analysed in 23 soil samples (0-10 cm layer) from the Swiss soil monitoring network (NABO) together with total organic carbon (TOC) and black carbon (BC) concentration, as well as some PAH source diagnostic ratios and molecular markers. The concentrations of the sum of 16 EPA priority PAHs ranged from 50 to 619 microg/kg dw. Concentrations increased from arable, permanent and pasture grassland, forest, to urban soils and were 21-89% lower than median numbers reported in the literature for similar Swiss and European soils. NABO soils contained BC in concentrations from 0.4 to 1.8 mg/g dw, except for two sites with markedly higher levels. These numbers corresponded to 1-6% of TOC and were comparable to the limited published BC data in soil and sediments obtained with comparable analytical methods. The various PAH ratios and molecular markers pointed to a domination of pyrogenically formed PAHs in Swiss soils. In concert, the gathered data suggest the following major findings: (1) gas phase PAHs (naphthalene to fluorene) were long-range transported, cold-condensated at higher altitudes, and approaching equilibrium with soil organic matter (OM); (2) (partially) particle-bound PAHs (phenanthrene to benzo[ghi]perylene) were mostly deposited regionally in urban areas, and not equilibrated with soil OM; (3) Diesel combustion appeared to be a major emission source of PAH and BC in urban areas; and (4) wood combustion might have contributed significantly to PAH burdens in some soils of remote/alpine (forest) sites.

Carbon↗

PubMed2004

Evaluation of sequentially-coupled POP fluxes estimated from simultaneous measurements in multiple compartments of an air-water-sediment system.

Bulk atmospheric deposition fluxes, air-water exchange fluxes, particle settling fluxes out of the upper water column, sediment trap fluxes in deep waters, and sediment burial fluxes of polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) were simultaneously measured in the Koster Fjord, eastern Skagerak, on the Swedish west coast. The aim of the study was to compare the magnitude and direction of the compound fluxes in the system in order to diagnose key fate processes. The PCB and PAH fluxes via net atmospheric deposition, settling particles out of the surface and through deep waters, as well as into the accreting underlying sediments were shown to be remarkably similar, agreeing within a factor of a few for any given target compound. Fluxes of all PCB and PAH target compounds remained fairly constant with water column depth. Thus there was no evidence for net desorption from sinking particles. The net unidirectional and near balancing of vertical fluxes suggests a net transport of PCBs and PAHs from the atmosphere to the continental shelf sediments in the Koster Fjord, which is consistent with the hypothesis that the shelf sediments are important sinks for these compounds.

Air Pollution↗

PubMed2004

Evaluation of the role of black carbon in attenuating bioaccumulation of polycyclic aromatic hydrocarbons from field-contaminated sediments.

The significance of black carbon (BC) for the bioavailability of polycyclic aromatic hydrocarbons (PAHs) was examined by using historically contaminated intact sediment cores in laboratory exposure experiments with the deposit-feeding amphipod Monoporeia affinis. Log values of amphipod biota-sediment accumulation factors (BSAFs) were significantly related to log BC, whereas log BSAFs were related to log octanol-water partition coefficients only in background sediments containing less BC. In the background sediments, the BSAF for polycyclic aromatic hydrocarbons (PAHs) was 1 to 2 for phenanthrene, with lower values for more hydrophobic PAHs, indicating an increase in nonequilibrium conditions with increasing PAH molecular size. For the near-equilibrated phenanthrene and fluoranthene, higher BSAFs were measured during exposure to background sediments, with BSAF decreasing to <0.1 in contaminated sediments in the Stockholm waterways. In situ caged mussels (Dreissena polymorpha) exhibited field BSAF values (relative to sediment-trap-collected suspended matter) for polychlorinated biphenyls (PCBs) of 0.1 to 0.4, but for PAHs of similar hydrophobicity and molecular size, the field BSAFs were much lower and in the range 0.002 to 0.05. This PAH-PCB dichotomy is consistent with recently reported much stronger binding to diesel soot (a form of BC) for PAHs than for PCBs of equal hydrophobicities. Lower BSAFs for the near-equilibrated PAHs (phenanthrene and fluoranthene) in the urban sediments relative to the background sediments were consistent with the larger presence of BC in the urban sediments. This study provides the first linked BSAF-BC field data that supports a causal relationship between strong soot sorption and reduced bioavailability for PAHs.

Adsorption↗

PubMed2003

Influence of soot carbon on the soil-air partitioning of polycyclic aromatic hydrocarbons.

Soil-air partitioning is one of the key processes controlling the regional and global cycling and storage of polycyclic aromatic hydrocarbons (PAHs). However, the specific processes dominating the partitioning of PAHs between these two environmental compartments still need to be elucidated. Stable and distinct atmospheric conditions paralleling different soil properties are found at Tenerife island (28 degrees 18'N, 16 degrees 29'W), which is located in permanent inversion layer conditions, and they provide interesting model cases for the study of air-soil partitioning. Analysis of phenanthrene, pyrene, fluoranthene, and chrysene showed concentrations 4- to 10-fold higher below than above the inversion layer. Similarly, soil total organic carbon (TOC) and black carbon (BC) were 11 and 3 times higher, respectively, below the inversion layer than above. The octanol-air partition coefficient (K(OA)) derived model provides a good description of PAH soil-air partitioning coefficients (K(P)) below the inversion layer but underpredicts them in the area dominated by deposition of long-range transported aerosols without inputs of organic matter from local vegetation. Inclusion of soot carbon in the soil-air partitioning model results in good agreement between predicted and measured K(P) in this area but in overpredicted K(P) values for the soils under the vegetation cover, which shows that the influence of soil soot carbon on PAH air-soil partitioning depends on its abundance relative to soil organic carbon. Absorption into organic matter is the dominant process in soils containing high organic carbon concentrations, whereas adsorption onto soot carbon becomes relevant in soils with low organic carbon and high soot content.

Adsorption↗

PubMed2003

Optimization of a preparative capillary gas chromatography-mass spectrometry system for the isolation and harvesting of individual polycyclic aromatic hydrocarbons.

Operation parameters of a preparative capillary gas chromatography (pcGC) system were optimized to facilitate clean and efficient harvesting of individual polycyclic aromatic hydrocarbons (PAHs) for subsequent compound-specific radiocarbon analysis. For PAHs, the recommended optimized settings of the specially-designed pcGC cooled injection system (CIS) and preparative fraction collector (PFC) are: 5 s CIS solvent venting time, deactivation of CIS "stop flow" injection mode, autoinjector "fast injection" mode, 60 s CIS splitless time, 340 degrees C PFC switch temperature, and 30 degrees C (ambient) trapping temperature. These optimized conditions yielded highly reproducible, pure, and efficient pcGC harvesting of six PAHs with mass recoveries of 90-100% and purity of the isolates of 97-100%.

Flow Injection Analysis↗

PubMed2003

Global accounting of PCBs in the continental shelf sediments.

The recycling longevity of hydrophobic organic contaminants (HOCs) within the global environment is set by their permanent removal through processes such as degradation and burial in geological reservoirs. More than 90% of the global sediment burial of organic carbon (OC) occurs on the continental shelves, representing < 10% of the earth's ocean area. The propensity of HOCs to associate with organic matter, and the proximity of most population centers and thus presumed source areas to coastal regions, led us to investigate shelf sediments as a depository of significance for global HOC budgets. Here, the global inventory and burial fluxes of polychlorinated biphenyls (PCBs) in continental shelf sediments were estimated on a congener-specific basis from a database of 4214 distinct continental shelf surface sediment samples. To account for near-urban sampling bias, the locations of each datum relative to nearest population center were classified as Local (< 1 km), Regional (1-10 km), or Remote (> 10 km), according to a comprehensive vector map of the world (Digital Chart of the World) in a GIS environment. The global inventory of, for instance, PCB congener 153 was 1200 ton (95% confidence limit maximum: 2100 ton; and minimum 720 ton). The Remote sub-basin of the North Atlantic contains approximately half of the global shelf sediment inventory for most of the PCB congeners studied. The shelf sediment inventories of individual PCB congeners constitute significant fractions of their recently updated cumulative historical global emissions estimates. The estimated inventory in the shelf corresponds to about 10% of maximum emission estimates for lower-chlorinated congeners. However, for the more bioaccumulable, higher-chlorinated, congeners the shelf reservoirs appear to account for up to 80% of the estimated maximum cumulative global emissions. These shelf inventories represent 1-6% of the global industrial production of PCBs. The global burial fluxes were estimated to be on the order of 8-24 ton/yr each for the eight major congeners investigated, again, with the shelf constituting a more significant removal sink of the more chlorinated congeners. The permanent removal into deeper shelf sediments of PCB153 and PCB180 suggests that the global environmental mean residence times of these pollutants are on the order of 110 and 70 years, respectively. Hence, even after production and direct releases have been halted, we may expect to be exposed to such persistent pollutants for decades and centuries to come.

Environmental Exposure↗

PubMed2003

Soot sorption of non-ortho and ortho substituted PCBs.

Field-observations of distribution coefficients well above expectations from bulk organic-matter partitioning for several chlorinated aromatic compound classes have lead to the hypothesis that enhanced affinity to soot may not be limited to polycyclic aromatic hydrocarbons but may extend as a significant process for a wider range of hydrophobic organic compounds. This suggestion was here tested in soot-column sorption experiments with a series of ortho- and non-ortho substituted polychlorinated biphenyls (PCBs), using diesel particulate matter (NIST standard reference material SRM-1650) as model soot sorbent. For congeners of similar hydrophobicity, considerably higher affinities toward the soot sorbent were observed for the non-ortho substituted PCBs. Mono- to tetra-ortho substituted PCBs exhibited log-based soot-water distribution coefficients (K(sc)) from 5.25 to 5.51 l/kg(sc) at solute concentrations corresponding to 1-13 microg/l. In contrast, biphenyl, mono- and dichloro- non-ortho substituted PCBs yielded logK(sc) values between 5.09 and 6.35 l/kg(sc). These results are 20-50, and 75-110 times higher, respectively, than the corresponding K(ow)-predicted K(oc) numbers. This strong interaction with soot, particularly of non-ortho substituted PCBs, may fundamentally affect their environmental distribution and bioavailable exposure.

Adsorption↗

PubMed2002

Evaluation and optimization of two complementary cross-flow ultrafiltration systems toward isolation of coastal surface water colloids.

While colloidal phases in natural waters are important to the speciation and bioavailability of trace metals and organic compounds, accurate isolation of these submicron entities from their lower molecular-weight counterparts has proved challenging. Here, both laboratory and field experiments have been conducted to constrain integrity aspects of two different cross-flow filtration (CFF) systems. We tested both a commonly applied 5000 cm2 CFF system (Pellicon2, Millipore; manufacturer-specified 1 and 3 kDa cutoff) and a less studied mini-CFF system with a 50 cm2 membrane area (Pellicon Lab Scale XL, Millipore; with 5, 10, 100, and 1000 kDa cutoff). A natural water matrix amended with a series of fluorescently tagged colloidal probes was employed to demonstrate that a cross-flow ratio (CFR; retentate-to-permeate flux) > 15 was required for both of these systems to obtain high recoveries of colloids. Contrary to previous calibrations of CFF, also at colloid concentrations characteristic of natural waters, the established retention profiles for the colloid probes on these systems, when operated under CFR > 15, affirmed the manufacturer-specified cutoff values (in parentheses): 2.4 kDa (1 kDa), 3.3 kDa (3 kDa), 6.1 kDa (5 kDa) and 8.7 kD (10 kDa). A concentration factor (cf) > 10 was found necessary for the reliable determination of the colloidal pool of several elements in the surface waters of the open Baltic Sea. Application of CFR > 15 and cf > 10 returned recoveries around 100% for the studied organic carbon, Ca, Mo, Fe, Cu, and Ni on both systems. Furthermore, the trend of colloid association for the transition elements in the offshore Baltic surface waters followed expectations from their Irving-Williams series of coordination chemistry.

Biological Availability↗

PubMed2002

Soot-water distribution coefficients for polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans and polybrominated diphenylethers determined with the soot cosolvency-column method.

For many types of hydrophobic compounds, sorption non-linearity and solid-water distributions in the field well above expectations from organic matter partitioning models have lead to the proposition that strong adsorption to soot surfaces may not be limited to polycyclic aromatic hydrocarbons but may extend as a significant process for many aromatic compound classes. Here, the soot-water distribution coefficients (Ksc) were determined with the soot cosolvency-column method for homolog series of five polychlorinated dibenzo-p-dioxins (PCDDs), five polychlorinated dibenzofurans (PCDFs) and for two polybrominated diphenylethers (PBDEs). All compounds exhibited significantly stronger association with soot carbon than expected from estimates of their bulk organic-carbon normalized partition coefficients (Koc). The Ksc/Koc ratios (at aqueous concentrations of around 0.1-1 microg/l) were for PCDDs (up to tetrachlorination) 19-130 (median 25), for PCDFs (also up to tetrachlorination) 150-490 (median 300), and for both the tetra- and pentabrominated PBDEs a factor of 60. The particularly strong soot sorption for the PCDFs is of similar enhancement factors as previously elucidated for polycyclic aromatic hydrocarbons. Compound-class specific correlations between log Ksc and octanol-water partition coefficients (log Kow) were significant for both PCDDs and PCDFs (and with R2 > 98%). These may prove useful for anticipating variable fractions of dissolved exposures between different environmental regimes and putative remediation objects.

Adsorption↗