Environmental Pollution Series B, Chemical and Physical最新文献

Seasonal variations in fly ash collected from the electrostatic precipitator of a thermal power plant over a period of a year have been studied in parameters of (i) particle size, (ii) per cent silicate, (iii) haemolysis and (iv) contents of Ni, Pb, Mn, Zn, Hg, Cd, Mg, Fe, Ca, K, Cu, Sr, As, Se, Co and Cr. Monthly variations were noted in the above parameters.

Methodological investigations were undertaken to determine the optimal sizes of three types of transplanted low technology sampler—the spherical moss bag, the lichen Hypogymnia physodes and the tak sampler (a synthetic fabric).

The optimal sizes were qualified as those providing, for most metals, a combination of high concentrations, reliable values and dimensions which take into account practical considerations. Various sizes of these samplers were exposed for a period of 2 months near a source of atmospheric metal pollution. An analysis of the results allowed optimal sizes of these samplers to be recommended for future surveys: for the spherical moss bags, a dry weight of 0·1 to 0·2 g; for Hypogymnia, a thallus diameter of 0·8 to 1·2 cm and, for the tak samplers, a surface area of 70 cm².

The ash remaining from machine smoking of 12 different American cigarette brands has been examined by instrumental neutron activation analysis. The mean concentrations are (element concentration in μg g⁻¹): Al 6070; Ba 375; Br 420; Ca 161 500; Ce 11·1; Cl 23 000; Co 3·58; Cr 21·2; Cs 0·653; Eu 0·154; Fe 3040; Hf 1·33; K 151 000; La 10·3; Mg 12 800; Mn 1250; Na 3460; Ni 24·7; Rb 82·1; Sb 0·741; Sc 0·894; Se 0·361; Sr 373; Th 1·06; Ti 1910; V 11·1; and Zn 221. Arsenic was not detected in all the samples examined. The chemical composition of cigarette wrapping paper has been found to affect the elemental concentration in the ash examined. The possible source of the elements of interest in cigarette ash is discussed and the results are compared with the literature values.

Eggs of three representative species of seabirds (wedge-tailed shearwater Puffinus pacificus; red-footed booby Sula sula; and sooty tern Sterna fuscata) were collected in 1980 to determined differences in heavy metal, Se, and organochlorine residues among species nesting in the Hawaiian Archipelago and among the four nesting sites sampled (Oahu, French Frigate Shoals, Laysan, and Midway). Hg and Se were present in all eggs analysed, but Cd was not detected. Hg was usually highest in booby eggs, and there was a southeast-to-northeast trend toward higher concetrations in this species; booby eggs from Midway contained the highest mean concentration of Hg (0·36 μg g⁻¹, wet weight). Se consistently occurred at lowest concentrations in booby eggs. When Se and Hg concentrations were expressed as nanomoles per gram, Se constituted 94–96% of the combined total at each location for shearwater and tern eggs. In booby eggs, the proportion as Se declined significantly (α = 0·05) from Oahu (93·4%) westward to Midway (85·9%). Although DDT occurred in most of the shearwater eggs from each site, it was not found in booby or tern eggs. DDE occured in all eggs, but mean concentrations did not exceed 0·6 μg g⁻¹. DDE concentrations were higher in eggs from the two south-eastern nesting sites and were consistently highest in shearwater eggs. PCBs were found in most of the shearwater and booby eggs, but were not detected in tern eggs. Other organochlorines usually occurred more frequently in eggs of shearwaters than in other species. The only exception were α-HCH and HCB, which occurred more frequently in booby eggs. Kepone, heptachlor epoxide, chlordane compounds, and toxaphene were not detected. Differences in residue concentrations seem to reflect differences in diets and seasonal movements of the birds, and perhaps other factors such as atmospheric and oceanic transport of chemicals and physiological differences among the species.

An investigation of the sorption of As(III) and As(V) species by two humic acids (HA I and HA II) has shown that As uptake varies with pH, adsorbate concentration and ash content of the substrate. At fixed pH, the amount sorbed conformed to a Langmuir relationship, with calculated capacities in the region of maximum uptake (∼pH 5·5) being of the order of 70 (90) mmol kg⁻¹ for As(III) and 90 (110) mmol kg⁻¹ for As(V). The higher values (in parentheses) reflect the higher ash and Ca contents of HA II. Uptake decreased when the ash content was reduced by acid-washing or sample purification, or when F⁻ or EDTA was added, indicating that Ca and polyvalent cations can be involved in As retention. The dominant solution species involved appear to be H₃AsO₃ and H₂AsO₄⁻ and retention of these was subject to competition from other anions, in particular H₂PO₄⁻, and, to a lesser extent, CO₃²⁻ and SO₄²⁻. The environmental significance of the results has been considered.

Past refining activity deposited up to 1000 mg kg⁻¹ total mercury (Hg) in sediments of the estuarine Berry's Creek (New Jersey, USA), yet methylmercury levels in the sediment were below 10 μg kg⁻¹. The factors that control Hg methylation in this low-sality anaerobic sediment were analysed. When compared to a normally methylating control sediment, no significant differences were found in pH, E_h, microbial counts and methylating potential, but sulphide concentrations in Berry's Creek sediment were found to be unusually high. A causal connection between the elevated sulphide levels and low Hg methylation activity was established. In its current state, the contaminant poses little danger to biota, but a significant decline in sediment sulphide would be expected to increase the methylation and the biohazard of Hg. Should a site cleanup by dredging become necessary in the future, the contaminated dredge spoils should be prevented from weathering and should be speedily entombed in an anoxic sulphide-rich environment.

Simulated acid rain was shown to increase the leaching of cations from Sitka spruce and Calluna. The sum of the cations (Mg²⁺, Ca²⁺, Mn²⁺ K⁺ and Na⁺) was linearly related to the extent of H⁺ uptake (neutralisation) by young Sitka spruce trees. The response of Sitka spruce branches to a progressive decrease in [H⁺] in the simulated rain over 1 h was a rapid decrease in Ca²⁺, Mg²⁺ and K⁺ leaching. For both simulated mist and simulated rain at pH 3·5 cation leaching was greater as a result of acidification with H₂SO₄ rather than HNO₃ or an equinormal mixture of both acids; no significant difference was found between cation leaching when the rain was acidified with HNO₃ or the HNO₃/H₂SO₄ mixture. The leaching of total organic carbon, NO₃⁻, SO₄²⁻ and Cl⁻ was not affected by the acidity of the rain. However, some uptake of NO₃⁻ was observed when Sitka spruce was exposed to simulated rain acidified with HNO₃.