Suspended Particulate Matter Samples Research Articles

Suspended particulate matter in indoor air: adjuvants and allergen carriers

The overall purpose of this study was to investigate how airborne house dust particles may contribute to an allergic immune response, and thereby also to asthma and other respiratory symptoms. The following aims were set: first, to quantify and characterize indoor suspended particulate matter (SPM) with regard to amount, as well as elemental and size distribution, second, to identify possible mechanisms by which SPM may affect the allergic immune response. A vast majority of the particles in SPM samples from homes in Oslo were found to be less than 2.5 μm in diameter. This PM 2.5 fraction contained, in addition to a large amount of sulfur aerosols and silicates, a lot of soot particles. Most of these were less than 1 μm in diameter. Using an immunogold labeling technique, we found that these soot particles carried cat, dog and birch allergens on their surface. These results show that indoor SPM contains a lot of potential allergen carriers, i.e. soot particles (carbon aggregates), most of them less that 1 μm in diameter and therefore able to transport allergens deep into the respiratory tree. We further found that diesel exhaust particles (DEP), which is likely the main soot component of SPM, adsorbed several well-known allergens in vitro. Furthermore, SPM was found to elicit a local lymph node inflammatory response, and to have an adjuvant activity on the production of IgE antibodies to ovalbumin (OA).

Geographic variations in the nitrogen isotope composition of surface particulate nitrogen and new production across the North Atlantic Ocean

Natural 15 N/ 14 N ( δ 15N) was determined in suspended particulate matter (SPM) and plankton tow samples (20- and 233-μm mesh nets) during extensive surveys along E–W transects from Halifax, Nova Scotia, to the Canary Islands in the fall of 1992 and the spring of 1993. This is the first study reporting δ 15N measurements along with NO − 3 and NH + 4 uptake rates in the North Atlantic. During both cruises, the δ 15N of SPM and net-plankton was lower in oligotrophic waters compared with values in eutrophic areas. The lack of correlation between the euphotic zone integrated δ 15N SPM and NH + 4 concentration and NH + 4 uptake rate at both times suggested that the contrast between regions could not be explained by regenerated production, even though NH + 4 was the preferred N substrate in most regions. In fact, based on a correlation analysis, this study suggested that isotope fractionation during nitrate uptake and the residence time of N in SPM ( τ) were the two major factors controlling the δ 15N SPM in 1992. During the fall of 1992, the δ 15N SPM of the oligotrophic region ( τ of 100–170 d) was consistent with the accumulated product equation in closed systems and a δ 15N of new nitrate of 4–5‰. In contrast, in eutrophic regions ( τ of 7–40 d), the δ 15N SPM was consistent with an open system equation. Isotope fractionation ( ε) for growth on nitrate was estimated to be 2.4‰ in the upwelling off Morocco. In 1993, no correlations were observed between δ 15N SPM and nitrate dynamics, probably because of horizontal advection. Based on the low τ of 5–30 d, an open system equation was used with nitrate as the reactant, and it suggested variations of 2–3‰ in either the δ 15N NO3 or ε.

Multi-phase distribution of organic micropollutants in Xiamen Harbour, China

Xiamen Harbour, in the Xiamen Special Economic Zone of the People’s Republic of China, was studied for its water and sediment quality, by determining the levels of 16 polycyclic aromatic hydrocarbons (PAHs), 12 polychlorinated biphenyls (PCBs) and 18 organochlorine insecticides in water, suspended particulate matter (SPM), pore water and sediment samples from nine stations in the Harbour. Total PAH concentrations varied from 106 to 945 ng/l in water, <1 to 3548 ng/l in pore water, and 247 to 480 ng/g dry weight in surficial sediments. Total PCB levels varied from 0.1 to 1.7 ng/l in water, 2.7 to 34.8 ng/l in pore water, and <0.01 to 0.32 ng/g dry weight in sediments. The levels of all insecticides were in the range of 6.6–19.6 ng/l (water), 11.8–78.5 ng/l (pore water), and <0.01–0.58 ng/g dry weight (sediment). The levels of total hexachlorocyclohexane (HCHs) in sediments varied from <0.01 to 0.14 ng/g dry weight, and those of total DDTs were in the range of <0.01–0.06 ng/g dry weight. The micropollutants were present in higher levels in pore water than in surface water, due possibly to higher concentrations of dissolved organic carbon or colloids with which the hydrophobic pollutants are strongly associated. Such a concentration gradient implies a potential flux of pollutants from sediment pore water to overlying water. The levels of pollutants in sediments are one to several orders of magnitude lower than those found in 1993, suggesting their decreased inputs in recent years in the form of fresh and less contaminated material and possible degradation over a period of time. Further work is needed to quantify the levels of these contaminants in suspended particulate matter, which are currently below the limits of detection.

Allergens in Paved Road Dust and Airborne Particles

Paved road dust present on the surface of streets in Southern California consists of a complex mixture of soil dust, deposited motor vehicle exhaust particles, tire dust, brake lining wear dust, plant fragments, and other biological materials. The research presented here shows that allergens from at least 20 different source materials are found in the paved road dust. These include pollens and pollen fragments, animal dander, and molds. When paved road dust is resuspended into the atmosphere by passing vehicle traffic, allergen concentrations in the air are increased above the levels that would prevail without the vehicle traffic. Using immunological assays that measure the proteins extracted from environmental samples that bind to IgE antibodies present in the blood serum of allergenic patients, it is possible to measure the allergen concentrations present in paved road dust and in airborne particle samples. Total protein contributions to monthly average airborne TSP and PM_(10) concentrations are found to be in the range from 1 to 5.8 μg m^(-3), potentially accounting for a significant fraction of the airborne particulate organic material that has not been identified to date by GC/MS techniques. Results show that up to 5−12% of the allergenicity of atmospheric total suspended particulate matter samples at Long Beach and Rubidoux, CA, is attributable to paved road dust emissions. In an industrial area of urban central Los Angeles where there is less proximity to vegetation and domestic activities, the paved road dust contribution to airborne allergen concentrations is lower, accounting for approximately 0.5% of the total allergenic activity of the atmospheric particle samples. In conclusion, paved road dust when entrained into the atmosphere by passing traffic is a source of allergen exposure for the general population and could be more important in areas with more abundant vegetation or with closer proximity of populations to major highways than is the case for the Southern California air monitoring sites studied here.

Image analysis as a tool for measuring particulate matter concentrations and gut content, body size, and clearance rates of estuarine copepods: validation and application

The performance of image analysis in measuring suspended particulate matter concentrations was compared with that of the Coulter counter in different samples including latex spheres, diatoms and natural estuarine waters. The two techniques gave comparable numerical concentrations. Image analysis results also correlated positively with dry weight measurements of estuarine suspended particulate matter samples. The conversion of particle areas measured by image analysis into volumes was addressed by trying to determine the average height of the particles. This was done by plotting volume concentrations from the Coulter counter against area concentrations from image analysis. The resulting linear relationships were found to be significant in homogeneous samples like the spheres and diatoms but not in natural estuarine samples. Further measurements were done on cross-section views of natural particulate matter to estimate the actual height, which was found to be on the average 34% of its average diameter. Also validated is the use of image analysis in measuring body sizes and gut contents of copepods. Results show that the gut resembles a cylinder and its measurement is independent of the animal's orientation at the time of measurement. Body size measurements converted into carbon compared favorably with literature data.

Dynamics of Particulate Trace Metals in the Tidal Reaches of the Ouse and Trent, UK

Samples of suspended particulate matter (SPM) have been collected in the tidal reaches of the Ouse and Trent over seven surveys covering the annual cycle of riverine conditions. Settling experiments were carried out on water samples to differentiate permanently suspended particulate material (PSPM) from temporarily suspended particulate material (TSPM). The results indicated that PSPM, additional to the riverine component, was created within the turbidity maximum zone (TMZ) during tidal resuspension. The PSPM varied between 10% and 50% of the total SPM and could be transported quasi-conservatively down-estuary. The concentrations of particulate Cd, Fe, and Zn (available to 1M HCl) were determined in PSPM and TSPM, as well as samples of the bulk SPM. The trace metal concentrations in PSPM were seasonally variable and generally higher than in TSPM, which had relatively constant concentrations. The trace metal concentrations in PSPM and TSPM were used to develop a two-component, particle mixing model, which was applied to the interpretation of the bulk SPM concentrations of Cd and Zn. It is postulated that as the PSPM encounters the salinity gradient labile Cd and Zn desorb from the particles. On the basis of these results an additional mechanism for generating estuarine maxima in dissolved trace metals has been proposed.

Distribution and Fate of Organochlorine Pollutants in the Pearl River Estuary

Samples of surface sediment and suspended particulate matter (SPM) were collected from the Pearl River estuary, China, and the distribution and concentration of hexachlorocyclohexanes (HCHs), DDTs and polychlorinated biphenyls (PCBs) were extensively studied. The concentration ranges of HCHs, DDTs and PCBs in the sediments were 0.28–1.23 ng g −1, 1.36–8.99 ng g −1 and 0.18–1.82 ng g −1, respectively. The concentrations of HCHs, DDTs and PCBs in the SPM varied both with the sampling locations and the season of collection. Higher concentrations were recorded in the SPM as compared with sediments. The distribution pattern of such organochlorine compounds (OCs), in the Pearl River estuary, showed that sources were some major river mouths and input from Shenzhen Bay. The concentrations of OCs were, however, low as compared with other estuaries and seas. The environmental fate of the OCs during estuarine mixing was determined, in part, by physicochemical and biochemical properties. The absorption and sedimentation of SPM were also considered important factors. Marine sediments may, therefore, be regarded as an important reservoir of hydrophobic and persistent OCs.

Fate of artificial musk fragrances associated with suspended particulate matter (SPM) from the River Elbe (Germany) in comparison to other organic contaminants

Four artificial musk fragrances were detected in 31 suspended particulate matter samples of the River Elbe at Magdeburg during June 1996–May 1997. 1,3,4,6,7,8-Hexahydro-4,6,6,7,8,8-hexamethylcyclopenta(g)-2-benzopyran (galaxolide) and 7-acetyl-1,1,3,4,4,6-hexamethyltetrahydronaphthalene (tonalide) showed the highest levels (148–770 ng/g), which was in the same order as the concentration of the polycyclic aromatic hydrocarbon benzo(a)pyrene. The concentration of 4-tert-butyl-3,5-dinitro-2,6-dimethylacetophenone (musk ketone) was significantly lower (4–22 ng/g) and similar to the level of lindane contamination. 4-Acetyl-1,1-dimethyl-6-tert-butyldihydroindene (celestolide) was detected in more than half of the samples and in the same concentration range as musk ketone (<4–43 ng/g). The partition coefficients of selected musk fragrances in laboratory experiments were in the same order as for γ-hexachlorcyclohexane (HCH) and isomers. In comparison, the coefficients for tonalide in field measurements was significantly higher (9,55∗ 103 L/Kg) than the value for galaxolide (4,42∗ 103 L/Kg), musk ketone (1,7∗ 103 L/Kg) and γ-HCH (7,24∗ 102 L/Kg).

An assemblage model for cation binding by natural particulate matter

SCAMP (Surface Chemistry Assemblage Model for Particles) describes the equilibrium adsorption of protons and metals by natural particulate matter using a combination of submodels for individual binding phases. Interactions with natural organic matter are described with Humic Ion-Binding Model V, and adsorption by oxides with a surface complexation model that allows for site heterogeneity. An idealized cation exchanger is also included. SCAMP uses published parameters for Model V, and parameters for the oxide model are derived from published laboratory data for proton and metal binding by oxides of Al, Si, Mn, and Fe(III). The model is applied to two samples of aquatic suspended particulate matter (SPM), one riverine, the other estuarine, taking into account the proportions of the different binding phases. Simulations suggest that organic matter is the major determinant of surface (proton) charge for the riverine SPM, while fixed-charge clays are dominant in the estuarine material. Predictions of the pH dependence of binding of nine metals (Co, Ni, Cu, Zn, Sr, Cd, Cs, Eu, Pb) by the two SPM samples are in reasonable agreement with observations. The different components of the assemblage provide binding sites with a wide range of apparent equilibrium constants, and log-log binding isotherms therefore have shallow slopes, in the range 0.3–0.5. On a weight-for-weight basis, the metal binding strengths of the different phases increase in the order cation exchanger < silica < aluminium oxide ∼ ferric oxide < humic substances < manganese dioxide.

Fluoranthene and pyrene in the suspended particulate matter and surface sediments of the Humber Estuary, UK

As part of the UK-based Land-Ocean Interaction Study (LOIS) community programme, suspended particulate matter (SPM) and surface sediments have been collected from the Humber estuary, which is a large and complex estuarine system on the east coast of England fed by several rivers including the Trent and Ouse. The samples from four surveys were extracted and analysed to determine the levels of anthropogenic organic contaminants such as fluoranthene and pyrene. Their concentrations in SPM and surface sediments ranged from 44 to 1560 ng g −1 dry weight and 13–1969 ng g −1 dry weight, respectively, and displayed no strong seasonal variation. Mean fluoranthene and pyrene concentrations were higher in the Trent than in the Ouse for both SPM and sediment samples, and were elevated at a sewage outfall, suggesting a multiplicity of inputs for these two compounds. Fluoranthene and pyrene on SPM showed no correlation with salinity, although correlations with suspended solids concentrations (SSC) and particulate organic carbon (POC) have been confirmed.

Genotoxic substances in the St. Lawrence system I: Industrial genotoxins sorbed to particulate matter in the St. Lawrence, St. Maurice, and Saguenay rivers, Canada

AbstractPrevious investigations of organic genotoxins in industrial effluents discharged into the St. Lawrence Rivers system (Quebec, Canada) indicated that a substantial fraction of the genotoxicity is adsorbed to suspended particulate matter. This study used the SOS Chromotest to investigate the presence, potency, and behavior of particle‐bound genotoxins in the downstream ecosystem. The results indicate that although extracts of both suspended and sedimented particulate matter are genotoxic, suspended particulate matter samples are more potent in the absence of S9 activation, with the reverse being true for bottom sediments. The results confirmed a positive relationship between the genotoxicity of bottom sediment extracts and sediment organic matter content. A similar relationship between organic matter content and total polycyclic aromatic hydrocarbon (PAH) concentration indicates that putative genotoxins have physicochemical properties similar to the PAH class of contaminants. Conversion of PAH values to benzo[a]pyrene equivalents indicates that measured PAHs only account for a small fraction (∼10%) of the observed SOS Chromotest response. Sites that receive discharges from foundries, aluminum refineries, and petroleum refineries yielded several of the most genotoxic samples. Further analyses revealed that the genotoxicity of suspended and sedimented particulate matter extracts is empirically related to the genotoxicity of industrial discharges. Comparisons of total genotoxicity levels in suspended particulates and bottom sediments suggest that direct‐acting substances adsorbed to suspended matter are rapidly degraded and/or converted to more stable progenotoxins upon deposition. Further research is required to test this hypothesis and investigate effects on indigenous biota.

Spatial distribution, vertical profiles and budget of organochlorine compounds in Western Mediterranean seawater

Individual PCB congeners (IUPAC Nos. 28, 52, 44, 70, 101, 118, 153, 138, 187, 128, 180, and 170), hexachlorocyclohexanes (HCHs) and dichlorodiphenylethanes (DDTs) were determined in 15 samples of suspended particulate matter (> 0.7 μm) (SPM) collected in the Catalan Sea and the Gulf of Lions. Furthermore, 6 vertical profiles were sampled at the Ebro and Rhoˆne River mouths, Sicilian and Gibraltar Straits, off-shore Barcelona and in the open sea. Finally, 6 dissolved phase samples from the Catalan Sea were taken and analysed. The highest PCB and DDT concentrations were detected offshore Valencia (26 and 2.8 pg l−1, respectively). Other sources of pollution were identified at the Ebro transect. Spatial variability shows an enrichment of organochlorine compounds (OCs) in a thermohaline front located midway between the Iberian Peninsula and the Balearic Islands. Vertical profiles of OCs in the SPM show for the first time, a surface enrichment pattern exhibiting concentration maxima in phyto- and zooplankton zones and declining OC concentrations with depth, except nearby sewage disposal sites offshore from Barcelona. Concentrations of PCBs (28–63 pg l−1) and DDTs (0.8–4.3 pg l−1) in the dissolved phase were one order of magnitude higher than in the corresponding particulate phase (1.7–16.6 and 0.16–0.98 pg l−1, respectively). Residence times of the SPM were estimated at every depositional area ranging from 1.46 to 8.05 years for PCBs and from 0.46 to 1.32 years for DDTs. Concurrently, sedimentation rates of SPM ranged from 0.37 to 0.78 m d−1 for PCBs and 1.18 to 4.68 m d−1 for DDTs. The PCB budget in the seawater of the western Mediterranean was computed using a three ☐ model accounting for 2.4 and 14.1 t in the particulate and dissolved phases, respectively. The DDTs budget was estimated to be ca. 179 and 717 kg in the particulate and dissolved phases respectively. Finally, the input of PCBs through the Gibraltar and the output through Sicilian Straits amounted for 1.5 and 1.3 t y−1, respectively. Concurrently the corresponding input and output for PCBs were 92 and 82 kg y−1 through Gibraltar and Sicilian Straits, respectively.

Comparison of ASE and SFE with Soxhlet, Sonication, and Methanolic Saponification Extractions for the Determination of Organic Micropollutants in Marine Particulate Matter

The methods of accelerated solvent extraction (ASE) and supercritical fluid extraction (SFE) of polycyclic aromatic hydrocarbons (PAHs), aliphatic hydrocarbons, and chlorinated hydrocarbons from marine samples were investigated. The results of extractions of a certified sediment and four samples of suspended particulate matter (SPM) were compared to classical Soxhlet (SOX), ultrasonication (USE), and methanolic saponification extraction (MSE) methods. The recovery data, including precision and systematic deviations of each method, were evaluated statistically. It was found that recoveries and precision of ASE and SFE compared well with the other methods investigated. Using SFE, the average recoveries of PAHs in three different samples ranged from 96 to 105%, for ASE the recoveries were in the range of 97-108% compared to the reference methods. Compared to the certified values of sediment HS-6, the average recoveries of SFE and ASE were 87 and 88%, most compounds being within the limits of confidence. Also, for alkanes the average recoveries by SFE and ASE were equal to the results obtained by SOX, USE, and MSE. In the case of SFE, the recoveries were in the range 93-115%, and ASE achieved recoveries of 94-107% as compared to the other methods. For ASE and SFE, the influence of water on the extraction efficiency was examined. While the natural water content of the SPM sample (56 wt %) led to insufficient recoveries in ASE and SFE, quantitative extractions were achieved in SFE after addition of anhydrous sodium sulfate to the sample. Finally, ASE was applied to SPM-loaded filter candles whereby a mixture of n-hexane/acetone as extraction solvent allowed the simultaneous determination of PAHs, alkanes, and chlorinated hydrocarbons.

Amino acids in biofilm material on aluminium panels immersed in marine waters

Suspended particulate matter (SPM) and the biofilm material on aluminium panels immersed in the surface waters (∼ 1m) of Dona Paula Bay over a period of 10 d were analysed for their organic carbon (OC), organic nitrogen; (ON) and total hydrolyzable amino acids (THAA) concentrations; and for their composition. The OC, ON and THAA concentrations of the SPM did not vary much during the sampling period. As compared to this, on the aluminium panels the biofilm biomass (measured as OC and ON) and the biofilm THAA showed a non‐linear increase over the period of immersion. Carbon and nitrogen in the THAA varied from 6.61 to 23.52% of the total OC and 23.90 to 35.04% of the total ON of the biofilm material, and from 16.10 to 18.90% of the total OC and 36.63 to 52.04% of the total ON of the SPM. Aspartic acid, glycine, alanine, serine, leucine and lysine and glutamic acid were the most abundant individual amino acids in both the biofilm material and the SPM. The distribution of individual amino acids was very similar to that observed in the two major sources of organic matter, viz. terrestrial vascular plants and marine bacteria and microalgae. The mole fractions of most amino acids did not show variation over the period of observation, especially in the case of the SPM samples. However, the mole fractions of glycine and serine in the biofilm samples generally decreased during the period of observation. These changes are attributed to the increasing abundance of cells of diatoms and/or bacteria, as compared to the structural constituents of diatom cell walls and/or detrital material.

Chemistry of riverine and estuarine suspended particles from the Ouse-Trent system, UK

Three samples of suspended particulate matter (SPM), two riverine and one estuarine, were characterised by bulk chemical analysis, electron microscopy, chemical extraction, electrophoresis and acid-base titration. The river samples contained both mineral and biological material and were rich in organic matter (R. Ouse sample 24%, R. Trent sample 54%), while the estuarine sample consisted mostly of clay minerals, with only 9% of organic matter. The river particles had higher contents of base-extractable carbon and phosphate and acid-extractable trace metals than the estuarine sample. The electrophoretic mobilities of all three samples were negative, but acid-base titrations revealed differences in their proton-dissociating characteristics, the R. Ouse sample having ≈ 2 meq g −1 of pH-dependent charge titrating between pH 4 and 9, approximately twice the content of the R. Trent sample, and four times that of the estuarine sample. However, the estuarine sample had a relatively large fixed (negative) charge (≈ −0.7 meq g −1). Centrifugation-depletion experiments showed that for all three samples, phosphate adsorbed most strongly at pH 6 7, the particles releasing phosphate to solution at both low and high pH values. Trace metal adsorption experiments, carried out by centrifugation-depletion and, in the case of Cu, with an ion-specific electrode, showed that adsorption increases with pH, except in some cases at pH >7, where solution complexation reverses the trend. A simple metalproton exchange model provided an approximate description of the observations, and allowed comparison amongst metals and particle samples. The three samples adsorbed trace amounts of metals with the same selectivity: Cs < Sr < Co⋍ Ni⋍ Cd < Zn < Cu < Pb < Eu. The strengths of adsorption of a given metal by the three samples varied over an order of magnitude, increasing in the order Ouse estuary < R. Trent ⩽ R. Ouse. These results, and other published data, show that natural SPM varies appreciably in its (surface) chemical properties. The possibilities of accounting for the variability in terms of the properties of constituent particles are discussed.

Visibility‐reducing organic aerosols in the vicinity of Grand Canyon National Park: Properties observed by high resolution gas chromatography

Fine particle and total airborne particle samples were collected during August 1989 within the Grand Canyon (Indian Gardens (IG)) and on its south rim (Hopi Point (HP)) to define summertime organic aerosol concentration and composition as a function of elevation at Grand Canyon National Park. Inorganic chemical constituents were analyzed also to help place the relative importance of organics in perspective. Fine particle organic aerosols were approximately equal in concentration to sulfate aerosols at both sites. Monthly average mass concentrations for fine aerosol organics ranged from 1.1 μg m−3 (IG) to 1.3 μg m−3 (HP), while the organic aerosol concentration within total suspended particulate matter samples ranged from 1.9 μg m−3 (IG) to 2.1 μg m−3 (HP). Aerosol organics that could be evaluated by gas chromatography with flame ionization detection (GC‐FID) (elutable organics) constituted 27% to 53% of the total organics mass collected as fine or total aerosol. At each site, roughly half of the elutable organics fine aerosol fraction was composed of highly polar organic compounds. Distributions of the elutable organics were compared to Los Angeles fine aerosol samples and to distributions of authentic sources of aerosol organics. It was found that the Grand Canyon organic aerosol during August 1989 did not resemble diluted aged Los Angeles organic aerosol, indicating that most of the organic particulate matter at the Grand Canyon at the time studied originated from other sources.

Distributions and fluxes of non-detrital particulate Fe, Mn, Cu, Zn in the Humber coastal zone, U.K.

Samples of suspended particulate matter (SPM) were collected at an anchor station at the mouth of the Humber Estuary and in the Humber-Wash coastal zone (U.K.) during the winter (1988), spring (1990) and summer (1990). Non-detrital particulate trace metals (Fe, Mn, Cu and Zn) were determined in the SPM following digestion with 1M HCl. Concentrations of non-detrital particulate trace metals were higher at the anchor station than in the coastal waters, suggesting dilution of metal-polluted estuarine SPM with natural SPM originating from erosion of the adjacent coastline. The distribution of non-detrital Fe and Zn in the coastal waters could be explained in terms of the Humber Estuary being a primary source, whereas for non-detrital Mn and Cu, the estuarine source was less significant because of their participation in biogeochemical processes. A hydrodynamic model of the Humber-Wash region was used to quantify the fluxes of dissolved and non-detrital trace metals into and out of the Humber Plume. The calculations showed that 0–10% of Fe, 5–70% of Mn, 40–100% of Cu and 30–100% of Zn were transported in the dissolved phase. Interpretation of the mass balances showed that the additional source of non-detrital particulate trace metals was sediment resuspension, whereas important sources of dissolved trace metals were porewater infusions and, for Mn, photochemically induced dissolution of particulate Mn. The trace metal sinks were the sedimentation of particulate matter and adsorption from solution. The flux estimates were used to evaluate the likely impact of dissolved and non-detrital trace metals on the wider North Sea.

Polychlorinated dibenzodioxins and dibenzofurans in suspended particulate matter of the River Elbe 1994

In April/May 1994 during a period of high discharge in the German part of the River Elbe (9 stations) and its main tributaries (3 stations) samples of suspended particulate matter (SPM) have been collected by means of sedimentation chambers with sampling periods of three or four weeks. Subsequent analyses for polychlorinated dibenzodioxins and dibenzofurans (PCDD/F) have shown that the river enters Germany with a rather low PCDD/F-load which almost steadily increases to below Hamburg. Major sources of contaimination has been the input by the tributary Mulde and resuspension of contaminated sediments along the riversides. Downstream of Hamburg marine influence have caused a sharp decrease of PCDD/F-contents. Changes in the result of 1989, 1992/93 have been discussed.

Particle sources and trace element reactivity in the Humber plume

Samples of suspended particulate matter (SPM) collected from the Humber Estuary had higher concentrations of particulate metals than SPM from Holderness coastal waters (U.K.). Characterised SPM from both sources was used in laboratory experiments involving the uptake of radiotracer109Cd,137Cs,54Mn and65Zn. Kinetic experiments, over five days, showed that the rate and extent of uptake was highly dependent on particle type, with109Cd,54Mn and65Zn being more reactive with Humber Estuary particles than those from Holderness and137Cs having the opposite trend. Adsorption experiments were also carried out on suspensions in which SPM from the Humber Estuary and Holderness coastal water were mixed in various proportions. These experiments revealed that Kd for65Zn increased linearly with the proportion of Humber SPM, Kd for137Cs decreased linearly with increase in Humber SPM and Kd for54Mn and109Cd displayed non-linear behaviour. The results of the study were used to develop an algorithm for predicting the partition coefficients in the Humber Plume based on the extent of particle mixing from the two source regions. The use of206/207Pb ratios in determining the extent of particle mixing is discussed, along with the application of the algorithm to the modelling of particulate trace metal behaviour in the Humber-Wash coastal zone.

206/207PB isotopic ratios applied to particulate transport processes-North eastern Irish Sea

Samples of suspended particulate matter (SPM) were collected from the north eastern Irish Sea, under different tidal conditions. The SPM was extracted with 1M HCl and concentrations of Pb and stable isotopic ratios of Pb (206/207Pb) determined using atomic absorption spectrometry and ICP-MS. Lead concentrations were found to be in the range 49 to 115 μg g−1 for spring tides and 72 to 148 μg g−1 for neap tides. The206/207Pb ratios, which were between 1.140 and 1.194, were used to establish possible sources of SPM during the tidal cycle. Samples of surface sediments from along the coastline showed evidence of anthropogenic Pb contamination in the vicinity of Liverpool Bay, with low206/207Pb ratios of about 1.144, which increased northwards away from the estuary. The results are discussed in terms of the tidally-induced transport of SPM in the coastal boundary zone of the Irish Sea.