The seasonal variations in the water quality indices of dissolved oxygen, biological oxygen demand (BOD), turbidity, total solids, nitrates, phosphates, hydrogen-ion concentration (pH), temperature and faecal coliforms of the Warri River at five sampling points were investigated from July 1981 to July 1982.
Methodological investigations were undertaken to determine the replicability of the concentrations of metals in a number of low technology samplers. Most of these samplers were subsequently used for the main monitoring survey of atmospheric metal pollution in Armadale, an industrial town in central Scotland. The indigenous samplers included Hypnum (moss), Lecanora (lichen), Agropyron (grass) and surface soils. The transplanted samplers included spherical moss bags (acid washed), Hypogymnia (lichen) and tak (synthetic fabric). Other samplers were added for purposes of comparison: translated flat moss bags (acid washed), another two types of spherical moss bag (fresh moss and water washed), dead Hypogymnia and a fruticose lichen.
Traces of cadmium ion in solution, alone and together with different cadmium bonding agents (K2CO3, CaCO3, KH2PO4, Ca3(PO)4, Fe(NO3)3 and Fe(OH)3), were added to three soils of pH 5·0, 7·0 and 7·6, respectively, and incubated aerobically at 45°C for 6 days.
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.
Soil column studies were undertaken to determine the mobility of nitrilotriacetic acid (NTA) in agricultural topsoil and its effect on the solubility of Cd, Cu, Mn, Ni, Pb and Zn following land application of sludge containing NTA. The total weight of NTA retained on the columns was >99% of that applied, with the levels of leached NTA becoming undetectable after 56 days. The presence of NTA increased the solubility of all six metals studied, although the degree of solubilisation varied with the individual metal, NTA dose and sludge application rate. Such an effect may result in greater metal mobility in sludge-amended soils, with possible changes in availability to plants and/or groundwater contamination.
A study of the chemical characteristics of wet precipitation was carried out in central Switzerland. Wet-only samples were collected weekly at three sites during 1983 and 1984. The results were examined for spatial and temporal variations in the concentrations of major cations and anions and also compared with similar results from two other Swiss stations, one in the eastern part of the country and one at an alpine location. At the sites not under the direct influence of urban emissions, concentrations of sulphate, nitrate and chloride were very similar at altitudes of 515 and 950 m above sea level. Volume-weighted average concentrations observed were lower than at most other European sites used for comparison. Between 950 and 3500 m above sea level, concentrations decreased, but much less in the case of sulphate than in the case of nitrate. At sites surrounded by agriculture, most nitrate and sulphate was associated with ammonium, and not with hydrogen, ions. Anion acids were enriched in precipitation collected downwind of urban areas. The temporal variation in the concentration of sulphate and nitrate did not depend on location. It was determined by precipitation volume and seasonal factors; for instance, the increase in air temperature in spring, which was associated with an increase in sulphate. The most acidic events occurred during spring and summer months. They were characterised by an increase in the nitric acid content. Possible relationships between the variation in precipitation acidity and meteorological conditions are discussed.
This paper deals with certain physico-chemical properties of fly ash collected from a coal-fired power plant at Kanpur (26° 26′ N latitude and 80° 22′ E longitude), India. Textural analysis reveals that a major fraction of fly ash mass (65%) is composed of silt-sized particles (0·02 to 0·002 mm). Sand-sized particles (2·0 to 0·02 mm) represented 25%, while clay-sized particles (<0·002 mm) represented only 10%. The bulk density and optimum moisture content of freshly collected fly ash samples were measured, being 1·02 g cm−3 and 2·1%, respectively. Water extracts from fly ash were alkaline and contained excessive amounts of soluble salts.
Corn (Zea mays L.) and soybean (Glycine max L.) were grown on sandy loam alluvial soil amended with fly ash at rates ranging up to and including 25% by weight. Plant analysis data for 7 elements showed enhanced absorption of B, Cu, Mn and Zn with increasing rates of fly ash application. Phosphorus, potassium and calcium concentrations in the two crops were not affected by fly ash application.
The baseline levels of mercury in fish and sediments from the Niger delta area of Nigeria have been examined. The measured concentrations in fish varied from less than 10 μg kg−1 to 410 μg kg−1 wet weight and those in the sediments varied between 0·024 and 1·54 μg g−1 dry weight. The levels found in the samples from this area were generally low in comparison with levels found in other regions of the world and the 0·5 μg g−1 Hg in fish recommended for human consumption by the World Health Organisation. These results indicate that the Niger delta area of Nigeria is relatively unpolluted with mercury.
Levels of mercury and persistent chlorinated hydrocarbons were determined in the liver of dead birds of prey (n = 568) and owls (n = 310) collected in Norway in 1965–1983. The highest levels of mercury were found in osprey and white-tailed eagle, with median concentrations of 4·7 and 2·4 μg Hg g−1 liver respectively. The levels of DDE and PCB varied considerably, the highest levels of DDE being detected in white-tailed eagle and goshawk which had a median concentration of 2·0 and 1·9 μg DDE g−1 liver respectively. Highest levels of PCB were detected in osprey, gyr falcon and white-tailed eagle (5·0 μg PCB g−1). With a few exceptions the levels of HCB, γ-BHC and dieldrin detected were low. Mercury and organochlorine levels were also determined in unhatched eggs (n = 159) of raptorial birds collected in the same period. The levels of mercury were, with a few exceptions, low. The highest levels of DDE were found in eggs of merlin and sparrow hawk with median concentrations of 30 and 19 μg g−1 respectively, while the highest levels of PCB were found in eggs of white-tailed eagle and goshawk, with median concentrations of 13·9 and 12·3 μg PCB−1, respectively. It was not possible, from the present material, to demonstrate significant changes in contaminant levels over time. Nor was it possible to detect significant geographical differences. Although a very few samples of liver and eggs contained levels of mercury or organochlorines that might be considered toxic, the greater proportion of samples contained levels far below accepted critical limits.
This study reports an investigation into fluvial contamination by the Cwm Rheidol ZnPb mine near Aberystwyth, Wales. This mine was last worked at the end of the last century, but acidic drainage waters are still a major source of water-borne contamination to the River Rheidol, despite the installation of a static treatment plant below the mine over twenty years ago.
Distribution coefficients (Kd) indicate the capability of a soil to retain a solute and also the extent of its movement in a solution phase. The purpose of the study was to determine Kd values for the heavy metals Ni and Zn in soils, in order to evaluate the ability of different soils to retain the metals. Batch equilibrium experiments on Ni and Zn were conducted to obtain adsorption isotherms, Kd values and distribution curves for Ni and Zn, with six concentrations of test solutions and three soils. Ni and Zn adsorption increased significantly as the concentration of the cation increased in the test solution. The range of Kd values for Zn and Ni was 140–684 and 152–388 ml g−1, respectively, for the soils investigated. The Mecklenburg clay, with high cation-exchange capacity (CEC), gave high Kd values for both Ni and Zn. There was no consistent relationship between the Kd values and soil pH and organic matter. The distribution curves for Ni and Zn showed negative correlation between solution concentration of Ni and Zn and Kd values. The results of this study indicate better retardation of Zn as compared to Ni by the soils.
Measurements have been made to determine the levels of radioactivity in silt in the River Lea using the gross beta count rate method and γ-ray spectrometry. The results show that the environmental levels are very low and appear to be due to naturally occurring potassium, uranium and thorium and a small amount of 137Cs, probably from fallout. The evidence suggests that pollution due to radioactivity present in the river is negligible.
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.
A modified version of the ATDL urban dispersion model was applied to estimate annual SO2 and suspended particulate concentrations in the Golden Horn region of Istanbul. The emissions were categorised as area sources (residential and commercial districts or small industries) and point sources (power plants and large industries). The area sources were distributed into a 3 km square grid pattern. The concentrations predicted from the model were compared with the observed concentrations, the correlation coefficient being 0·874.
Aluminium concentrations in water have been measured at several points in time for more than 50 sites distributed along the Rivers Esk and Duddon, Cumbria, and their tributaries. Total aluminium (Altotal), inorganic monomeric aluminium (Alinorg) and organic monomeric aluminium (Alorg) were measured using a modified Driscoll technique. Concentrations were found to vary with season (flow rate) and geographical variation was often high. High Alinorg concentrations (200–300 μg litre−1), associated with low pH levels, were commonly found in tributaries in the upper reaches of the valleys, at high flow rates, and in catchments containing little or no improved agricultural land. Two catchments in the Duddon valley appear to be affected by afforestation and had even higher levels of Alinorg (400–600 μg litre−1). Two catchments in Eskdale were sampled in more detail. It was found that water quality changed markedly after the tributaries flowed through improved pasture land. Alinorg concentration fell and pH values rose. Those changes were associated with increased Ca concentrations, possibly the result of agricultural liming.
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.
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 relations were studied between concentrations of 20 trace elements in epiphytic lichens and in the substrate (bark). The bark was separated into two fractions: a 2 mm thick outer layer and the inner layer, not exposed directly to the atmosphere. For most elements a significant correlation was found between the concentrations in the lichen and the concentrations in the outer and inner bark. In general the element concentrations in the inner bark were appreciably lower than those in the outer bark and lichen. For some elements, including Zn and Cd, the concentrations in the inner bark were relatively high, indicating that for those elements the possibility of uptake from the substrate has to be seriously considered.
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.
