Concentrations Of Various Contaminants Research Articles

High atmospheric nitrogen deposition events over the North Sea

Atmospheric circulation patterns over the North Sea occasionally result in episodes of high concentrations of various contaminants. Synergistic chemical effects can act to enhance the deposition of nitrogen during these events resulting in highly episodic nitrogen inputs to the North Sea. Two such episodes are described and their causes interpreted. The problems of devising sampling strategies to quantify these events and assess their effects on phytoplankton communities are discussed.

Variability of organic contaminants in inter-tidal sandflat sediments from Manukau Harbour, New Zealand

Surficial sediments from five stations on inter-tidal sandflats within Manukau Harbour, New Zealand were sampled using a systematic sampling design to give three representative bulked replicates per station. Particle size analysis showed the stations to be similar, with poorly sorted fine to medium sand and mud contents of 21–26%. Sediment readily oxidizable carbon contents were low (0.22–0.73%). These parameters showed similar variability (CVs of 11–50%), both within and between stations, confirming their visual similarity. Organochlorine insecticides, PCBs (23 congeners) and polynuclear hydrocarbons (PAHs, 10 fluorescent compounds) were extracted from the sediments and determined to detection limits of 0.02–0.05 ng/g. An extraction procedure using a ternary solvent system (acetone/hexane/water) gave equivalent results to a standard method but was more rapid, used less solvent, and gave lower blanks. Levels of chlorinated organics were low. Highest levels for all contaminants occurred at one station (total PCBs 1.6 ng/g, DDT + metabolites 18 ng/g, dieldrin 0.38 ng/g lindane 0.34 ng/g, cis- + trans-chlordane 0.38 ng/g, total PAHs 3,740 ng/g). PAH levels were substantially lower at other stations (40–90 ng/g). Differences for other contaminants were not great, although there was a significant gradient of chlordane concentration between the stations. Variability in concentrations of contaminants was large both within and between stations (CVs of 2–126%). Normalizing the concentrations to organic carbon did not markedly alter the above trends, but demonstrated significant chlordane and PCB gradients, and increased the variability within many of the stations. The results were interpreted as indicating multiple contaminant sources, with major contributions from the treated sewage outfall and a more heavily contaminated industrialised inlet at the head of the harbour. The contaminants were not strongly associated with any particular sediment characteristic, with only PCBs strongly correlated with carbon levels.

Risk assessment and management of chemical contaminants in fishery products consumed in the USA.

In the USA a small proportion of fishery products are contaminated with appreciable amounts of potentially hazardous contaminants. However, risks to consumers are not generally high. Inorganic contaminants with the greatest potential for toxicity are antimony, arsenic, cadmium, lead, mercury, selenium and sulfites. Among organic compounds, polychlorinated biphenyls, dioxins, several chlorinated hydrocarbon insecticides, certain processing-related and aquaculture-related contaminants pose potential risks for consumers. Log-normal distributions appear to provide good descriptions of the pattern of variation of contaminant concentrations among different geographic areas, and some contaminants (mostly organic) appear to be much more variable than others. This variability offers a solution for reduction of exposure through restricting the harvest of aquatic organisms from specific sites, and by excluding certain species. It is recommended that: (i) existing State and Federal regulations and environmental monitoring be strengthened and enforced to minimize contamination of the aquatic environment; (ii) a program of shared responsibility be instituted, where Federal agencies develop a set of monitoring and inspection practices and state agencies assume responsibility for primary control, site closures and advisories issue; (iii) research and public education by government agencies and health professionals be expanded to determine actual risks and approaches to manage them; (iv) mandatory labeling be considered for specific contaminants; (v) a better system requiring international agreements be developed in order to minimize the differences among various national regulatory approaches.

Why Don’t Great Lakes Fish Reflect Environmental Concentrations of Organic Contaminants? – An Analysis of Between-Lake Variability in the Ecological Partitioning of PCBS and DDT

We have reviewed the literature on PCBs and DDT in the Great Lakes ecosystem, in an attempt to explain between-basin and between-species variation in fish contamination. Empirical models were developed, using log-linear multiple regressions, to link tissue contaminant concentrations to environmental levels (water and sediments) as well as basin-specific ecological attributes. Concentrations of PCBs and DDT in sediment and water can explain between-basin variability in fish contaminant levels only when basin-specific ecological attributes are taken into account. The important factors that appear to determine the ecological partitioning of persistent organic contaminants are fish lipid content, trophic level of the fish in question, and the trophic structure of the food chain. Multiple regressions of these variables explain 59% (DDT) to 72% (PCBs) of the variation in contaminant concentrations of 25 species of Great Lakes fish.

Organic Contaminants in Adult Aquatic Insects of the St. Clair and Detroit Rivers, Ontario, Canada

Night-flying Trichoptera and Ephemeroptera were attracted using long-wave ultraviolet light and collected from 8 Canadian sites adjacent to the St. Clair and Detroit rivers. Gas chromatographic analysis of the extracts from 40 samples of the insects revealed significant concentrations of pentachlorobenzene (QCB), hexachlorobenzene (HCB), octachlorostyrene (OCS), and 16 polychlorinated biphenyl (PCB) congeners in almost all animals collected. Principal component analysis accounted for 84% of variation in contaminant concentration among samples. The principal components (PCs) correlated highly with concentrations of 9 hexa-, hepta-, and octachlorobiphenyls (PC-I; 46% of overall variation), 4 tetra- and pentachlorobiphenyls (PC-II; 17% of variation), QCB, HCB, and OCS (PC-III; 8%), and 2 trichlorobiphenyls (PCs IV and V; each 6% of variation). Values of PC-I were significantly greater among Detroit River than among St. Clair River samples. Values of PC-II were highest for samples from upstream stations on the two rivers. Values of PC-III were higher for St. Clair River samples than for Detroit River samples. These trends are consistent with patterns observed in other biota and sediment previously collected from equivalent sites. Contaminant levels also varied among taxa collected from the same site, possibly because of different larval feeding habits or microdistribution, or adult flight ability. Collection of adults has potential as an inexpensive alternative to aquatic sampling methods in surveys of biota for organic contamination.

Distribution of Contaminants in Clams and Sediments from the Huron-Erie Corridor. II–Lead and Cadmium

The St. Clair River is a major center for the Canadian petrochemical industry, while the shoreline of the Detroit River is heavily urbanized. The extent of lead and cadmium discharge from these sources was assessed by determining contaminant concentrations in unionid clams ( Lampsilis radiata siliquoidea) and sediments from 102 sites in Lake St. Clair and from the Canadian side of the Detroit and St. Clair rivers. Overall, lead and cadmium levels in sediments averaged 20.5 and 0.18 mg kg −1 dry weight, respectively. These concentrations are lower than those reported in prior studies, but the decline is likely a consequence of shifts in sampling methodology and site location. Lead concentrations in clams (7.1 mg kg −1) averaged only one half those in the sediments, whereas cadmium concentrations were 30 times higher in clam tissues than in the surrounding sediments. There was a significant positive correlation between lead and cadmium concentrations in sediment, and between the concentrations of both metals and the amount of organic carbon present. There was no correlation between the level of either lead or cadmium in clams and levels in the sediments from which they were collected. Patterns of variation in contaminant concentrations support the conclusion that industries along the Canadian side of the St. Clair River are the primary source of both lead and cadmium.

Quantification and Removal of Some Contaminating Gases from Acetylene Used to Study Gas-Utilizing Enzymes and Microorganisms

Acetylene generated from various grades of calcium carbide and obtained from commercial- and purified-grade acetylene cylinders was shown to contain high concentrations of various contaminants. Dependent on the source of acetylene, these included, at maximal values, H(2) (0.023%), O(2) (0.779%), N(2) (3.78%), PH(3) (0.06%), CH(4) (0.073%), and acetone (1 to 10%). The concentration of the contaminants in cylinder acetylene was highly dependent on the extent of cylinder discharge. Several conventional methods used to partially purify cylinder acetylene were compared. A small-scale method for extensively purifying acetylene is described. An effect of acetylene quality on acetylene reduction assays conducted with purified nitrogenase from Azotobacter vinelandii was demonstrated.

Chemical and biological investigations of a transformer accident at Binghamton, NY

A transformer fire occurred in a state office building in Binghamton, NY on February 5, 1981. Particulates from inside surfaces of ceiling panels on 16 of the 17 floors had concentrations of polychlorinated dibenzofurans (PCDFs) ranging from less than 1 part per million (ppm) to 1200 ppm while polychlorinated biphenyl (PCB) concentrations varied from 28 ppm to 23,000 ppm. In spite of the wide variations in contaminant concentrations, complete analytical data from 11 floors showed that there was a consistent PCDF/PCB ratio (0.067 +/- 0.026) and also consistent PCDF isomer group distributions (tetra-CDFs, 33 +/- 5%; penta-CDFs, 40 +/- 3%; hexa-CDFs, 18 +/- 7%; hepta-CDFs, 6 +/- 3%). It was found that the particulate samples could be successfully ranked in order of their degree of chemical contamination by an in vitro bioassay. The bioassay was based on induction of keratinization or changes in morphology in mouse epithelial cells. Animal toxicology experiments were carried out with a soot sample containing a PCDF concentration which approximated the mean value found on the ceiling particulates. The single dose oral LD values of the soot and its benzene extract equivalent, each administered to female guinea pigs in 0.75% methyl cellulose, were 410 and 327 mg/kg, respectively. These results demonstrated that the soot matrix had virtually no effect on the toxicity of the chemical contaminants in the soot. Morphological alterations in liver tissues from animals receiving the soot were found after examination by electron and light microscopy.(ABSTRACT TRUNCATED AT 250 WORDS)

Chemical and Biological Investigations of a Transformer Accident at Binghamton, NY

A transformer fire occurred in a state office building in Binghamton, NY on February 5, 1981. Particulates from inside surfaces of ceiling panels on 16 of the 17 floors had concentrations of polychlorinated dibenzofurans (PCDFs) ranging from < 1 part per million (ppm) to 1200 ppm while polychlorinated biphenyl (PCB) concentrations varied from 28 ppm to 23,000 ppm. In spite of the wide variations in contaminant concentrations, complete analytical data from 11 floors showed that there was a consistent PCDF/PCB ratio (0.067 ± 0.026) and also consistent PCDF isomer group distributions (tetra-CDFs, 33 ± 5%; penta-CDFs, 40 ± 3%; hexa-CDFs, 18 ± 7%; hepta-CDFs, 6 ± 3%). It was found that the particulate samples could be successfully ranked in order of their degree of chemical contamination by an in vitro bioassay. The bioassay was based on induction of keratinization or changes in morphology in mouse epithelial cells. Animal toxicology experiments were carried out with a soot sample containing a PCDF concentration which approximated the mean value found on the ceiling particulates. The single dose oral LD values of the soot and its benzene extract equivalent, each administered to female guinea pigs in 0.75% methyl cellulose, were 410 and 327 mg/kg, respectively. These results demonstrated that the soot matrix had virtually no effect on the toxicity of the chemical contaminants in the soot. Morphological alterations in liver tissues from animals receiving the soot were found after examination by electron and light microscopy. Rabbits dermally exposed to the soot and its benzene extract at 500 mg/kg showed evidence of hypertrophy of centrilobular hepatocytes. In addition the rabbits exposed to the soot extract had a local inflammatory reaction at the site of application. In a subchronic feeding experiment carried out for 90 days with guinea pigs, the lowest effect level was found with an accumulated dose of 1.2 mg soot/kg. The observed effects included salivary gland duct metaplasia and decreased relative thymus weights. Based on the chemical analysis data and literature LD values for the more toxic 2,3,7,8-substituted polychlorinated dibenzo-p-dioxins (PCDDs) and PCDFs, it was calculated that the soot contained the equivalent of 44 ppm 2,3,7,8-tetra-CDD in terms of toxicity to guinea pigs. This was in close agreement with the value of 58 ppm derived from the acute oral toxicity experiments. Air sampling, accomplished on 8 floors in the final stages of the building cleanup, showed maximum total PCDF and 2,3,7,8-tetra-CDF concentrations of 264 and 23 pg/m, respectively.

The Distribution of Mercury, Cesium‐137, and Plutonium in an Intermittent Stream at Los Alamos

AbstractThis paper summarizes the results of a study on the distribution of Hg, 137CS, 238Pu, and 239,240Pu in channel sediments and adjacent bank soils in an intermittent stream used for treated liquid effluent disposal since 1963.Concentrations of the three radionuclides and Hg in stream bank soils were comparable to adjacent channel sediments demonstrating that the stream bank serves as a deposition site for chemicals released to the channel. This finding has important implications on the long‐term behavior of effluent contaminants since other studies at Los Alamos have shown that the vegetated stream banks retard downstream movement of chemicals bound to soils and provide a pathway for transport of these materials to biota.Concentrations of the radionuclides and mercury were more uniformly distributed with distance and depth in the channel sediments than in the bank soils. The action of periodic surface water in the channel partially explains those differences. Statistical analysis of the data revealed that 50 to 85% of the variability in contaminant concentrations in bank and channel locations was due to variation with distance while depth contributed relatively little to variability.

Ventilation in relation to toxic and flammable gases in buildings

The toxic and flammable gases and vapours that lead to hazards in buildings are discussed. The trends in accidental deaths in the home in England and Wales from gas poisoning are examined: the number of deaths per annum from town gas have fallen dramatically from the peak in 1963 of 1230 to less than 200 in recent years, but the number due to carbon monoxide from heating appliances has steadily increased from about 10 in the early 1950's to about 70 in recent years. The influence of buoyancy on the dilution by ventilating air of accidental leaks of toxic and flammable gas is discussed and the limiting cases, where buoyancy effects are negligible and where they dominate, are theoretically investigated. The variation of contaminant concentration with time is derived for situations where buoyancy has a negligible effect on the mixing process and it is shown by experiments in a mechanically ventilated office that turbulent mixing with the room air can extend to the corners of the room, above cupboards and below tables. Where buoyancy dominates layers can readily form, this is important when considering explosion hazards. The concentration distribution in roof layers for ventilation systems extracting air through an outlet near to, but not in, the roof is calculated theoretically. The theory assumes that the mixing of the gas with the ventilating air takes place by molecular diffusion and is shown by the comparison with experiment to apply in practical situations. It is shown theoretically that a leak of town gas near to the floor mixes readily with the room air during its flow towards the roof. Simple experiments using nitrous oxide demonstrated the relevance of the theoretical approach to conditions that can arise in buildings. The combination of ready mixing of a buoyant plume during its vertical motion and subsequent mixing only by molecular diffusion once a layer has formed against the roof explains how a gas accumulation may have led to the explosion at Ronan Point. Theoretical results are tabulated and presented on design charts for controlling gas hazards in buildings by ventilation for a wide range of practical situations. Attention is drawn to possible future hazards from gas accumulations in the space above false ceilings and in near horizontal service common ducts and tunnels. A new technique is suggested for measuring ventilation, mainly for mechanically ventilated buildings when there is appreciable adventitious ventilation. This uses a steady release of tracer gas and enables both the mechanical ventilation output rate and the adventitious input rate to be determined from a single series of measurements. These cannot be separated in the usual tracer gas dilution technique.