Environmental Pollution Series B, Chemical and Physical最新文献

The capacities of the mosses Rhacopilopsis trinitensis (C. Muell) Britt.et Dix., Stereophyllum virens Card., and Thuidium gratum (C. Muell) Jaeg. to sorb and retain Pb, Cu and Cd ions from solution were studied. All the species showed very high capacities to sorb these metal ions from single-ion as well as mixed-ion solutions. Ca and Mg ions were most readily released from the moss tissues on sorption of the metal ions. The sorbed metal ions were strongly retained in the moss tissues, but may be significantly leached out by strongly acidic solutions. The three species did not differ remarkably in their capacities to sorb and retain the metal ions.

The objective of this study was to develop a phytoassay procedure using common duckweed. The results suggest that the assay is simple, sensitive and very economical.

Those substances evaluated for relative toxicity by the phytoassay included most of the constituents listed in Illinois' general standards for water quality. Based on the duckweed assay, the maximum permissible concentrations of Ba(II), Cd(II), Fe(III), Ni(II), and Se(IV) are lower than the water quality standards. On the other hand, similar limits for B(III), Cr(VI), Cu(II), F(I), Pb(II), Mn(II), SO₄(II) and phenol are higher than those concentrations stipulated in the water quality standards. For Cl(I) and Zn(II) the limits developed by the phytoassay are equal to the standards.

The results suggest that duckweed is a promising indicator of aquatic toxicity. Duckweed assay should be further explored so that its value can be evaluated when more data are available.

Levels of four metals were measured in the shells of Elliptio complanata, collected from three localities in the Great Lakes, having widely different levels of contamination. The levels of ten metals were measured in the outermost shell and overlying periostracum, cut from each of the annual rings of two shells. Zn (unlike Pb) displayed a much greater affinity to the soft tissues than the shell. Levels of Al, Cu, Fe, Ni, Pb and Zn were significantly higher in the outer periostracum of the shell than in the inorganic prismatic shell layer. In spite of high Pb levels in industrial effluent at one of the locations, inorganic Pb was not deposited in the prismatic shell layer. Metal concentrations in the periostracum did not follow the chronological trends in the prismatic layer. Levels of Al, Fe and Mn decreased with clam age, whereas concentrations of Cu and Zn were greatest during years of fastest growth.

The amounts of zinc, cadmium, lead and copper were determined in the hepatopancreas and whole body of the woodlouse Porcellio scaber (Crustacea, Isopoda) and soil and leaf litter collected from 89 sites in the counties of Avon and Somerset, south-west England. Maps were drawn to compare the regional distribution of concentrations of metals in the samples.

The main source of zinc, cadmium, lead and copper pollution was centred on Avonmouth to the north-west of Bristol, the site of a primary zinc, lead and cadmium smelting works. Concentrations of all four metals in the hepatopancreas, whole woodlice, soil and leaf litter were above background levels over a large area on all maps which, in the case of cadmium in the hepatopancreas, extended for 25 km to the east of the smelting works.

The correlation coefficients between the concentrations of each metal in woodlice and soil, and between woodlice and leaf litter, were positive and statistically significant (P < 0·001) in all cases. At individual sites, however, particularly those associated with disused mining areas, rubbish tips or busy roads, the concentrations of zinc, cadmium, lead and copper in woodlice could not have been predicted accurately from the levels of metals in leaf litter or soil due to the large scatter of data points along the lines of ‘best fit’.

Future exercises in pollution monitoring should include analysis of at least one representative of the primary consumers of vegetation to enable the ‘availability’ of metals to the fauna to be reliably assessed. Porcellio scaber is probably the ideal ‘indicator species’ in the UK because it has a strong affinity for zinc, cadmium, lead and copper, is large enough to provide sufficient tissue for analysis, and is common in a wide range of rural and urban habitats.

Analysis of cedar bark samples and deposition samples in the Nagatsuta area, Yokohama, Japan, shows that there is contamination by heavy metals, Cr, Zn, Cu and Pb, as indicated by enrichment factor values, particularly in the parts adjacent to the highway. It is suggested that motor traffic is the major source. The soil is enriched with respect to these heavy metals by a factor of 2 to 361. It is suggested that this contamination occurs primarily by aerial deposition. A correlation between heavy metal levels and distance from the road was established and a power regression analysis, ln Y = a + B ln X, gave a fit(p < 0.001) indicating an exponential decay function.

The accumulated levels of the metals, Pb, Cd, Cu, Ni, Zn, Mn and Fe were determined in forest mosses from south-west Nigeria. Distinct gradients were observed only with Pb and Zn, and a small zone of random contamination with Cu was identified in parts of the east and the south-east. This contamination was possibly a result of the use of copper-based fungicides and pesticides in cocoa farms in the area.

The levels of the metals are compared with those in forest mosses in some other parts of the world.

Competitive adsorption, by activated carbon, of phenolic compounds from 2- and 3-solute mixtures was studied. Phenols with 2 or 3 chlorine substituents (2,4-dichlorophenol and 2,4,6-trichlorophenol) were strongly adsorbable and adsorbed preferentially to 2-chlorophenol, phenol and m-cresol. Data generally fit Freundlich adsorption isotherms. The dichloro- and trichlorophenols adsorbed more strongly than predicted by the Polanyi-based model when in competition with other phenolics. The cumulative adsorption capacities for the mixtures containing all phenolic compounds were lower than those for individual compounds.

The rhodizonate spot test for Pb has been adapted to the detection of Pb contamination of soil. Depending upon the method of extraction chosen, Pb is detectable to 400–700 μg g⁻¹ in the dry soil sample. Extraction is carried out by heating or shaking with nitric acid, followed by filtration. The filtrate is brought to pH 1·5 with citrate using a pH meter or an indicator. The extract is spotted on filter paper and treated with freshly prepared aqueous sodium rhodizonate. Heating extracts more Pb than shaking, but a relatively stable percentage of the Pb present is extracted by shaking for 30 s. This latter method of extraction may be used as part of a rapid, simplified procedure requiring a minimum of apparatus. Use of citrate for pH adjustment eliminates the problem of crystallisation encountered with tartarate, as specified in the original procedure. Soil extracts with pH < 1 showed rapid fading of the pink Pb-rhodizonate spot, and those with pH > 3 gave the intense yellow colour of free rhodizonate, which tended to obscure the pink Pb-rhodizonate colour. Differences in the effect of heating and the effect of extraction time on Pb and Fe levels were observed, with Pb more readily extracted than Fe. Use of extracts with low levels of Fe made possible visual endpoint detection for the adjustment of pH. Using the shaken extraction method with a series of 107 samples, positive results were obtained for 82 samples with > 700 μg Pb g⁻¹, negative results for 10 samples with < 400 μg Pb g⁻¹ and mixed results for 15 samples in the range 400–700 μg Pb g⁻¹. Selection of a cutoff value of 500 μg Pb g⁻¹ eliminated false negative results in a pilot screening trial of 38 samples prepared by the heated extraction method.

The shellfish Chione (Austrovenus) stutchburyi has been studied as a bio-indicator for lead in an estuarine environment near Christchurch, New Zealand. Over four years the mean lead level in the soft tissue was 1·16 μg g⁻¹. The levels responded to significant rainfall events in the catchment area. Over the four years a fall in lead levels corresponded to reduced lead inputs into a river feeding the estuary. In addition to climatic and lead source changes, seasonal effects and shell size also need to be considered, as lead levels fall in the early summer and are elevated in small shellfish. The use of the shell as a bio-indicator for lead necessitates sectional and surface shell analysis rather than whole shell analysis. Both shell age and depth into the shell are variables that associate with lead.