Roadside Surface Research Articles

Trace zinc and copper concentrations in roadside vegetation and surface soils: a measurement of local atmospheric pollution in Alice, South Africa

The concentration of zinc and copper in 180 grass and associated soil samples collected in triplicate samples were determined. The triplicate field data were averaged to yield mean soil and vegetation metal concentrations at each sample location. The zinc levels ranged from 7.0 ± 1.4(S.D.) — 134.8 ± 6.3(S.D.) μgg‐1, dry weight, in grass and from 0.6 ± 0.2 (S.D.) — 119.5 ± 3.9 (S.D.) μgg‐1, dry weight, in surface soils. The results showed that zinc contents are high close to the road traffic and fall off rapidly with distance from the road edge. Similar studies on copper gave lower values ‐1.0 ± 0.2(S.D.) — 8.1 ± 1.4(S.D.) μgg‐1, dry weight in soil samples which did not show any correlation with distance from road traffic. Analysis of standard soil reference materials (SRM 2710) gave results (Zn, 6636.5 ± 43.7(S.D.); Cu, 2725 ± 49.1(S.D.)) which are found to be in good agreement with certified NIST values (Zn, 6952 ± 91; Cu, 2950 ± 130). Results of spiking experiments with vegetation gave high percentage recoveries for both elements (Zn, 96.6 ± 1.3(S.D.)% and Cu, 95.5 ± 0.5(S.D.)%). Blank determinations were done for background corrections.

High concentrations of heavy metals in neighborhoods near ore smelters in northern Mexico.

In developing countries, rapid industrialization without environmental controls has resulted in heavy metal contamination of communities. We hypothesized that residential neighborhoods located near ore industries in three northern Mexican cities would be heavily polluted with multiple contaminants (arsenic, cadmium, and lead) and that these sites would be point sources for the heavy metals. To evaluate these hypotheses, we obtained samples of roadside surface dust from residential neighborhoods within 2 m of metal smelters [Torreón (n = 19)] and Chihuahua (n = 19)] and a metal refinery [Monterrey (n = 23)]. Heavy metal concentrations in dust were mapped with respect to distance from the industrial sites. Correlation between dust metal concentration and distance was estimated with least-squares regression using log-transformed data. Median dust arsenic, cadmium, and lead concentrations were 32, 10, and 277 microg/g, respectively, in Chihuahua; 42, 2, and 467 microg/g, respectively, in Monterrey, and 113, 112, and 2,448 microg/g, respectively, in Torreón. Dust concentrations of all heavy metals were significantly higher around the active smelter in Torreón, where more than 90% of samples exceeded Superfund cleanup goals. At all sites, dust concentrations were inversely related to distance from the industrial source, implicating these industries as the likely source of the contamination. We concluded that residential neighborhoods around metal smelting and refining sites in these three cities are contaminated by heavy metals at concentrations likely to pose a health threat to people living nearby. Evaluations of human exposure near these sites should be conducted. Because multiple heavy metal pollutants may exist near smelter sites, researchers should avoid attributing toxicity to one heavy metal unless others have been measured and shown not to coexist.

Trace zinc and copper concentration in roadside surface soils and vegetation—measurement of local atmospheric pollution in Alice, South Africa

Surface soil and grass samples were collected from ten locations perpendicular to a major road in Alice and were analyzed for zinc and copper. The results revealed an association between zinc concentration and distance from road traffic. An association was also revealed between soil zinc and grass zinc which suggests same source for the metal in samples. The results for copper did not show any correlation between sample concentration and distance from road traffic. Neither did it show any correlation between soil zinc and soil copper or between grass zinc and grass copper which suggests different sources for the elements.

Bromine in soil ? An indicator of automobile exhaust lead pollution?

Soil Br concentrations, determined by neutron activation analysis, ranged from ‘natural’ levels of 11 to 18 ppm to values of up to five times as high in Glasgow roadside and park surface soil. Elevated Br concentration in soil is shown to be a useful qualitative indicator of automobile exhaust Pb pollution, although care must be exercised in sample selection to avoid erroneous interpretation of data. The excess Br originates from ethylene dibromide used to scavenge Pb from automobile engines in which tetraethyl Pb is used as an anti-knock agent.