Jack E. Fergusson

Trace elements in street and house dusts: sources and speciation

The sources and speciation of trace elements in street and house dusts are reviewed. Soil is a major component of both dusts, but a number of elements are enriched in both materials. These include Pb, Zn, Cu, Cd, As, Sb, Cr, Ca, Na, Au, Cl and Br. They arise from a number of contributing and polluting sources. In the case of house dust, some elements, such as Cu, Co, As, Sb, Zn, Cd, Au, Cl, C and Pb, are produced in the house. There are a number of problems associated with the determination of the speciation of trace elements in dusts. These include the low concentrations of many of the elements, and the interpretation of the results from selective sequential extractions. The mobility and potential availability of the trace elements from dust lies in the order Cd greater than Zn, Pb greater than Mn, Cu greater Fe.

The elemental composition of street dust from large and small urban areas related to city type, source and particle size

Abstract Twenty-six elements have been determined in street dust from London (U.K.), New York (U.S.A.), Halifax (Canada), Christchurch (N.Z.) and Kingston (Jamaica). The cities divide into two groups, London and New York (large urban) and Halifax, Christchurch and Kingston (small urban). The elements fall into two groups, those that originate mainly from soil (e.g. Al, K, Na, Th, Ce, La, Sm and Ti), and those (e.g. Ca, Cd, Pb, Cr, Zn, Cu and Au) that primarily originate from other sources, including cement, tyre wear, car emissions and salt. The first group of elements are in lower concentration in London and New York than in the other cities, while the reverse holds for the second group of elements. The concentrations of most elements increase with decrease in the size of the dust particles. The metals, Cd, Pb, Cu, Zn, Mn and Fe were sequentially extracted from the dust into five fractions, exchangeable metal, carbonate bound metal, MnFe oxide bound metal, organic bound metal and the residue.

EFFECTIVENESS OF A COMMONLY USED SEQUENTIAL EXTRACTION TECHNIQUE IN DETERMINING THE SPECIATION OF CADMIUM IN SOILS

Abstract Various cadmium-sorbed and cadmium-coprecipitated “soil phases” were prepared and sequentially extracted using the five-step method of Tessier et al. Reagent selectivity was assessed by performing sequential extractions of individual cadmium-spiked phases, and the extent of cadmium redistribution between phases during the course of the extractions was gauged by sequentially extracting a range of “synthetic” soils and and a real soil into which cadmium-spiked phases had been mixed. Reagent selectivity was in some cases very good. The main shortcoming in reagent selectivity was that a portion of the cadmium sorbed on humic acid and clay remained associated with those substrates until step 3 of the sequential extractions. Release during this step would lead to the incorrect classification of the formerly sorbed cadmium as “bound to easily reducible manganese oxides and/or amorphous iron oxides”. Redistribution of the cadmium liberated from each contaminated phase of the synthetic soil and real soil samples during the course of each sequential extraction was minimal. However, in some cases the pH of the material being extracted markedly influenced the relative proportions of cadmium liberated during steps 1 and 2 of the extractions.

Heavy metal and organic matter concentrations and distributions in dated sediments of a small estuary adjacent to a small urban area

Abstract The concentrations and distributions of the heavy metals Cr, Mn, Fe, Ni, Cu, Zn and Pb and organic matter were investigated in dated sediment cores of a small micro-tidal estuary adjacent to a small urban area. Metal concentrations are greatest in sediments deposited since European settlement, when the sedimentation rates have been slowest. The concentrations are lowest in rapidly deposited sediments and in sediments formed in pre-European times. Significantly heavy metal pollution has entered the estuary since 1850. The concentration distribution of the metals and organic matter, however, has been modified by the sedimentation rate which in turn was determined by changes in drainage and the use of the adjacent land area. For example, rapid sedimentation occured when the contributing rivers were swept of excess sediment derived from stormwater drains and nearby horticulture areas. Despite maximum anthropogenic metal fluxes to the estuary the extra ‘clean’ sediment diluted the heavy metal concentrations in the sediments. The concentration profiles of the metals can be explained by the historical events occurring around the estuary and rivers, and the introduction of storm water drains and a sewage plant.

The elemental composition and sources of house dust and street dust

Abstract The elemental compositions of house dust, street dust and soil have been determined for 26 elements on material collected in Christchurch, New Zealand. The elements Hf, Th, Sc, Sm, Ce, La, Mn, Na, K, V, Al and Fe may be considered to be soil-based and contribute about 45–50% to house dust and 87% to street dust. The elements which are enriched (>3 times) in the dusts relative to the levels found in local soils, are Br, Cu, Cl, Pb, Zn, Cr, Ca, Co, As and Sb in house dust, and Zn, Cr, Cu and Pb in street dust.

The analysis and levels of lead in human teeth: a review

Human teeth are a readily accessible biological tissue for which the analysis of lead has been used for the classification of people in terms of their lead exposure and absorption. However, there are three significant problem areas in the interpretation of the analytical results for lead in teeth. First, the lead is not homogeneously distributed throughout the tooth; secondly, the lead levels vary with tooth type, which relates to the age of a tooth. Lastly, there are significant variations in results from different laboratories, which, in part, reflect problems with contamination, pretreatment and analytical methods. Since teeth provide an integrated historical record of a persons lead exposure they have some attractive features as biological indicators, compared with materials such as blood. But considerable care and attention to detail is necessary to obtain reliable data.

Lead in teeth: the influence of the tooth type and the sample within a tooth on lead levels.

Different sections of permanent teeth have been sampled and the lead levels estimated using carbon furnace AAS. Very high levels of lead (500-3400 micrograms g-1) and other trace metals (Cd, Cu, Fe and Zn) occur on the surface of the teeth, falling off rapidly a few micrometers into the teeth. Lead levels in the bulk enamel of incisors vary depending on the position within the tooth, the highest values occur on the lingual side near the gums and the lowest levels on the labial side near the tooth top. The ratio of the concentration of lead in enamel to dentine and to circumpulpal dentine was found to be 1:2:6, and within the dentine the lead levels were highest in the root dentine. The root dentine in the permanent teeth of eight, near complete or representative, sets of teeth was analysed for lead. The ratio ([Pb]tooth/[Pb]total set) decreased in the order: first molars greater than central incisors greater than lateral incisors greater than canines greater than premolars greater than second molars greater than third molars. This order inversely correlates with the age of formation or eruption of the teeth, i.e. the older teeth have the highest levels of lead in the dentine. Dentine appears to be the best material to use to estimate lead, particularly in relation to the integrated lead intake of a person. Dentine lead was determined in a small sample of deciduous teeth obtained from children living in rural areas. The levels were found to be slightly less than for children living in new housing urban areas and significantly less than for children living in older houses of urban areas.

Concentrations and sources of cadmium, copper, lead and zinc in house dust in Christchurch, New Zealand

The amounts (microgram m-2) and concentrations (microgram g-1) of cadmium, copper, lead and zinc have been measured in house dust in Christchurch, New Zealand. For 120 houses surveyed the geometric mean concentrations of the four metals are 4.24 micrograms g-1, 165 micrograms g-1, 573 micrograms g-1 and 10,400 micrograms g-1, respectively. In addition eleven variables, such as house age, carpet wear and traffic density, were recorded for each property and the results analysed with respect to their effects on the amounts and concentrations of the four elements. The amounts of all the metals were highly correlated with the overall dustiness of the houses, which was found to be predominantly determined by the degree of carpet wear. No one dominant source of cadmium was identified, although several minor sources including carpet wear, galvanized iron roofs and red/orange/yellow coloured carpets were implicated. Petrol lead and lead-based paints were identified as significant sources of lead in house dust. Rubber carpet underlays or backings were identified as a significant source of zinc, with some contribution from galvanized iron roofs. Road traffic and probably the existence of a fire place appear to contribute to the copper levels.

Lead in house dust of Christchurch, New Zealand: sampling, levels and sources

Lead in house dust was determined in different areas of Christchurch, New Zealand. The mean lead level in newer (post-1950) areas of the city was 460 micrograms g-1, whereas in older (pre-1950) areas it was 830 micrograms g-1. These levels also relate to the type of building material (brick or wood, respectively) and type of paint used (non-lead or lead paint, respectively). For the newer areas of the city, it was estimated that approximately 90% of the lead was derived from petrol additives (via street dust and aerosol), whereas in the older areas, approximately 50% of the lead was estimated to come from petrol lead and 45% from paint lead.

Seasonal variations in the concentrations of cadmium, copper, lead and zinc in leaves of the horse chesnut (Aesculus hippocastanum L.).

The concentrations of cadmium, copper, lead and zinc have been measured in the leaves of a deciduous tree the horse chestnut (Aesculus hippocastanum L.) over the period of their lifetime (7 months). The average concentrations for the total sample based on ash weight are: (microg g(-1)) cadmium, 0.197; copper, 129; lead, 294; and zinc, 299. The temporal trends in the concentrations of the metals can be related to their dominant source. Copper and zinc concentrations are highest in the new leaves and decrease with time, suggesting the main source of the elements are uptake from the soil. The decrease occurs partly because of dilution by leaf material as it increases over the growing period. In the case of zinc, however, aerial deposits appear to be also a significant source. Lead concentrations, on the other hand, show an increase with time, which can be related to increasing deposits from aerosol lead arising from the combustion of petrol lead. The increase is enough to offset the dilution effect. For cadmium there is no significant trend, but the tendency is a decrease with time. It is not possible, however, to distinguish between soil uptake and aerial deposit as both are small compared with increase in leaf material.