Environmental Pollution Series B, Chemical and Physical最新文献

A simple amalgamation/CVAAS technique is applied to investigate the influence of various meteorological parameters on the atmospheric distribution of mercury. For the volatile and particulate fractions, a clear relationship is encountered, respectively, with the ambient temperature and the amount of total suspended particulates. These parameters are of major importance, masking the effect of others. For the residential area studied, an average total mercury concentration of 6 ng per cubic metre is calculated. The particulate fraction amounts to 1–30%. A source contribution from a neighbouring industrial region is observed.

The amounts of Mn, Cr, Pb, Zn, Cu and Ni in the lichens Squamarina crassa, Teloschistes lacunosus, Ramalina maciformis, Diploschistes steppicus and Caloplaca ehrenbergii growing in the Negev Desert, Israel, were measured. The amount of Pb in S. crassa growing close to a main motorway was relatively high and much higher than in the soil—the substrate of S. crassa. The high coefficients of variation for Mn and Cu found in several lichens are attributed to large particles entrapped in the lichen thallus. It is suggested that the low coefficients of variation found for Zn in all the lichens studied indicate that this element occurs in small, well-dispersed particles.

Measuring the heavy metal content of desert lichens is important because of their biomonitoring potential and also because snails and goats feed on them.

Aquatic bryophyes have been analysed for aluminium, manganese and zinc to assess the feasibility of using these plants as bioindicators of metal loadings to acid streams and lochs in two regions of Scotland. Bioconcentration occurred in all waters but increased hydrogen ion concentrations in the water were associated with decreased metal concentrations in the bryophytes. Release of aluminium, manganese and zinc from the bryophytes by hydrogen ions may make a significant contribution to the loadings of these metals in acid waters.

Arsenic levels have been determined in the hair and nails of male employees of a wood preservative treatment factory in Nigeria. Mean As concentrations of 11·6, 7·5, 4·1 and 1·6 μg g⁻¹ were measured in hair samples from four groups of employees, depending on the nature of their work and the duration of their employment in the factory. Mean As levels of 7·4, 4·8, 2·7 and 1·0 μg g⁻¹ were also measured in nails for the same groups. The employees involved in the preparation of the treating fluids, the chemical impregnation process and handling of the treated timber showed consistently higher As levels in both tissues than those who were less exposed to the chemicals. No correlation between the measured As levels and age of the donors was established, nor was a reasonably good hair As—nail As correlation obtained for any of the four exposure groups. This study, however, minimized possible effects of age, sex, hair colour and chemical treatment. Mean As levels of 1·2 and 0·64 μg g⁻¹ as ‘control’ values were also determined in hair and nails, respectively of ‘non-exposed’ persons in the same age group as the factory workers. The elevated As levels measured in both tissues reflected a relatively high degree of exposure to the chemicals.

Total non-residual (TNR) concentrations of Fe, Mn, Co, Ni, Cr, Cu, Pb, Zn and Cd have been determined in sediments from ten stream populations in North West England using a rapid 0·5 HCl leaching technique. It is shown that the technique can successfully be used as a first stage in a reconnaissance survey designed to identify trace metal pollution in stream sediments. The TNR trace metal concentrations are extremely variable in the sediments and a number of approaches are assessed in order to interpret the data in an environmentally useful manner. (i) Spatial variations in the distributions of the TNR trace metals in individual stream populations can be used to identify specific pollution sources, which often impose ‘man-made fingerprints’ on the sediments. (ii) In order to establish baseline concentrations for all the stream sediments, an artificial background sediment (ABS) is identified and sediments which have suffered pollution are identified as those whose TNR trace metal concentrations exceeds an $E{\overline{x}}_{ABS}$ + 2s parameter, in which $E{\overline{x}}_{ABS}$ is concentration of an element, E, in the ABS. The degree of pollution is assessed by an index of pollution (IP), which is related to the $E{\overline{x}}_{ABS}$ + 2s parameter. (iii) Partitioning of the trace metals in the non-residual sediment fractions is investigated using a five-stage sequential leaching technique. The application of the technique to a series of polluted and non-polluted stream sediments shows that the partitioning characteristics of a number of the TNR trace metals differ in respect to their host components. Further, the partitioning signatures of some of the TNR trace metals, especially that of Cd, are different in polluted and non-polluted samples.

The concentrations of zinc, cadmium, lead and copper in the tissues of the littoral isopod Ligia oceanica from three sites near to a primary zinc, lead and cadmium smelting works on the southern shore of the Severn Estuary and an unpolluted site in the Menai Strait, Anglesey, were determined. The concentrations of zinc, cadmium and copper in whole L. oceanica from the contaminated sites were significantly higher than in specimens from the uncontaminated site, although the levels were only about one-and-a-half, three to four and twice as great, respectively. The amounts of lead in L. oceanica from all four sites were very small. The hepatopancreas was the most important storage organ of heavy metals and, at all sites, contained more than 50% of the total zinc, cadmium and copper in the body.

The concentrations of heavy metals were compared in the tissues of L. oceanica and in two ‘more terrestrial’ isopods, Oniscus asellus and Porcellio scaber, collected from the same habitat at one of the contaminated sites. The mean concentrations of copper were the same in the hepatopancreas of all the isopods. However, there were large differences in the extent to which zinc, cadmium and lead had been accumulated by this organ in the three species. Analysis of the gut contents of the isopods revealed that all three species had been feeding on leaf litter derived from nearby trees, rather than on seaweed washed up onto the shore. Therefore, it was concluded that the extent to which zinc, cadmium and lead were assimilated by L. oceanica, O. asellus and Porcellio scaber must have been related to differences in their digestive physiology, rather than to choice of food material containing different concentrations of metals.

The rate and extent of the methylation of inorganic mercury has been shown to depend markedly on the chemical speciation of the mercury and the methylating agent. The presence of mercury (II)—chlorine covalent bonding has an inhibitory effect on methylation by methyl cobalamin (CH₃CoB₁₂) and in natural sediments. The rôle of radical and carbonium ion methylation mechanisms has also been investigated. In a typical estuarine sediment the extent of mercury methylation is as follows: Hg(OAc)₂ ⪢ Hg(cyst)₂ > Hg(cyst) (Hcyst)Cl > Hg(meth)₂²⁺ > Hg(eth)₂²⁺ > Hg(Hcyst)Cl₂ > HgCl₂ > (HgCl₂)₂ pen, where OAc = acetateHcyst = cysteine, meth = methionine, eth = ethionine and pen = penicillamine. This is consistent with mercury methylation arising by attack of a methyl carbanion (CH₃⁻) on inorganic mercury (II) ions derived by microbial breakdown of the original and mercury compounds added.

Copper, nickel and iron levels were higher in samples of substrate, leachate and surface water of copper-nickel mine tailings than in those from uranium mine wastes or a control area, which were similar. Nickel and iron were also elevated in the vegetation from the copper-nickel workings. The gut of resident voles was contaminated by copper and nickel and the skin and hair by nickel and iron. Higher whole body burdens of copper and nickel were attributed to the higher levels in gut and skin. Higher levels of iron observed in bone and kidney tissue were the only indications of internal deposition of these metals. Cobalt, zinc and lead levels, when detectable, in leachate, vegetation and water differed little from, or were below, control levels in both tailings. Total body concentration of cobalt was lowest in animals from uranium mine tailings; their low skin contamination was due to low levels in the substrate. Total body burden of zinc did not differ among sites. No internal deposition of cobalt was seen. Although lead levels were higher in uranium mine tailings than elsewhere, no differences were seen in lead concentrations in vegetation or resident voles. Radium-226 was detected only in the samples and voles of uranium mine wastes; the voles carried the radium-226 in their gut, skin and skeleton.