The great skua combines the traits favouring accumulation of pollutants. Levels of PCB and DDE are high, but there is no evidence of egg-shell thinning. There are indications of age-accumulation of heavy metals in adult great skuas and renal cadmium levels are very high in some individuals. Selenium concentrations correlate with mercury and cadmium concentrations. Possible protective effects of selenium are discussed. Levels of PCBs, DDE, HCB and dieldrin in eggs all correlate with each other, and vary greatly between individuals, suggesting individual variation in excretory rates, feeding habits or distribution in winter. Mercury levels in primary feathers correlate with those in liver so may be used to monitor without killing birds. The feeding habits and migrations of the great skua make it a suitable indicator of offshore pollution in the north-east Atlantic.
Fertilised eggs at various stages of development and newly hatched fry of medaka Oryzias latipes were exposed to a series of concentrations of the water-soluble extract of toluene. Static bioassays were conducted and TL50 calculations made. In addition, the embryos were examined for the presence of developmental anomalies. The mean 96 h TL50 for eggs was 54 mg/litre. The early (<3·5h) and late (>192 h) stages were more sensitive than the average. The newly hatched fry were not as sensitive to toluene as were the embryos.
A procedure for observing the effects of dissolved copper and other metal ions on the submersed aquatic macrophyte Elodea canadensis has been described. Metal concentrations have been determined which inhibit light-induced oxygen evolution from plant segments after short-term exposure (24h), and which produce phytotoxicity in whole plants over a longer period (28 days). These results are discussed in terms of the phytotoxic effects on Elodea resulting from dissolved metal ions present in polluting concentrations in natural water bodies or from the use of added copper as an aquatic herbicide.
Analytical data are presented for metal concentrations in aquatic bryophytes growing in the streams of a lead-zinc mining area in Dyfed, Wales. The highest concentrations of zinc (7023 ppm/dry weight) and of lead (16,000 ppm/dry weight) were recorded in plants growing nearest the mines, reflecting the extent of metal pollution in the water. The widespread occurrence of some species in these areas suggests a wide range of tolerance. The chemical form of zinc in stream water from the Frongoch mine, in which the zinc concentration was 58 ppm, was demonstrated to be Zn2+.
The effects of long-term zinc exposure on juvenile salmon were assessed by measuring changes in their voluntary food intake, growth and rate of zinc accumulation. The food intake of salmon surviving concentrations as great as the 21-day LC50 was initially reduced but returned to amounts observed for control fish within 10 to 20 days. After 45 days' exposure, the food intake of these individuals was greater than that of the controls. Growth rates of salmon exposed to zinc (maximum concentration estimated to cause mortality ≤50% during an acute bioassay) and offered rations of 2.0 or 3.5% dry body weight per day were not reduced during a three-month period. However, caloric content of salmon at the higher concentrations showed a small decrease during the experimental period. Zinc concentration of salmon feeding to satiation once daily and exposed to zinc increased during the first two months of exposure before reaching a maximum, while zinc concentration of salmon offered sub-excess rations (2.0 and 3.5% per day) increased linearly during a three-month period.
Lead poisoning due to the ingestion of lead fishing shot was shown to be the cause of death of a number of mute swans Cygnus olor Gmelin. The area in which they were feeding was shown to be heavily contaminated with fishing shot. The results of clinical, histopathological, haematological and analytical examinations are reported.
Four sludges, three of which contained Ca(OH)2, FeCl3 or Al2(SO4)3 for phosphorus removal, were compared as to degradation in soil. All sludges degraded rapidly but rates <25 mg/g approached CO2 evolution of untreated soil in 15 days while higher rates required about 50 days. Each of the sludges contained lime which, at each addition, increased the soil pH. The Ca-sludge produced the greatest pH increase and evolved larger amounts of CO2 than the Fe- and Al-sludges. The Ca-sludge evolved 52%, the untreated Al-sludge 20% and the Fe-sludge 5% of the sludge C. Calcium carbonate added to the soil increased the degradation of the Al-sludge and no significant differences amongst sludges were noted in the percentage of sludge C evolved. The degradation of these sludges was more related to soil pH than to chemical treatment of the influent for phosphorus removal.
The potential radiological implications of environmental tritium releases must be determined in order to develop a programme for dealing with the tritium inventory predicted for the nuclear power industry which, though still in its infancy, produces tritium in megacurie quantities annually. Should the development of fusion power generation become a reality, it will create a potential source for large releases of tritium, much of it in the gaseous state. At present about 90% of the tritium produced enters the environment through gaseous and liquid effluents and is deposited in the hydrosphere as tritiated water. Tritium can be assimilated by plants and animals and organically bound, regardless of the exposure pathway. However, there appears to be no concentration factor relative to hydrogen at any level of food chains analysed to date. The body burden, for man, is dependent on the exposure pathway and tissue-bound fractions are primarily the result of organically bound tritium in food.
Young channel catfish Ictalurus punctatus were exposed to 1, 100, 200 and 400 ppm dietary mirex. Specific activities of lactic dehydrogenase, malic dehydrogenase, glutamate pyruvate transaminase and glutamate oxaloacetate transaminase were determined in brain, gill, liver and muscle at one, two, three and four weeks. Few changes in enzyme sppecific activities were found which were attributed to mirex exposure. It appears that mirex, even at high dietary exposure levels, is relatively innocuous to these enzyme activities.
Direct or indirect discharging of municipal sewage into water bodies commonly results in water pollution and prolific growth of aquatic vegetation. To avoid this problem, part of the secondary-treated municipal wastewater collected from the city of Isfahan is used for irrigating a 5-ha agricultural research plot where various kinds of crops and trees are grown under close observation. The scheme takes advantage of the ‘living filter’ concept, where the biosystem consisting of soil and plants acts as a filter for removal of the polluting load that otherwise would have disturbed the environment. Experimental results obtained show that a nearly complete renovation of wastewater has been effected without causing any permanent or long-term damage to the surrounding ecosystem. Furthermore, an increase in product yield is achieved without any detectable lack in quality. It is concluded that the scheme is a feasible and successful method for re-utilisation of wastewater, provided that correct land management is exercised during the operation.
On first mixing digested sewage sludge with soil the proportions of the Cu and Zn in the sludge that are extractable to conventional extractants fluctuate considerably. Thus Cu extractable from sludge alone shows a marked initia fall to a minimum at 8–29 days and then rises to near its initial value; from a sludge—soil mixture there is a less marked decrease (over 8–16 days) and the extractable Cu returns to near its initial value over 90–100 days. The Zn extractable from sludge alone falls to a minimum at 8–16 days and then rises to near the initial value, but the Zn extractable from sludge-soil mixtures rises sharply over 2–4 days and then falls to near the initial value over 50–100 days.
Eighty-five samples of leaves of Ricinus communis L. (Euphorbiaceae) representing five populations—four collected from healthy, and one from polluted, environments—were studied to establish the relationship between environmental pollution and foliar epidermal features. The data obtained were analysed statistically.
The acute toxicity of methamidophos and three other compounds to fingerlings of the common carp Cyprinus carpio L. was determined. The 96-h LC50 values were 68 mg/litre for methamidophos, 1.7 mg/litre for carbaryl, 0.21 mg/litre for lindane and 50 mg/litre for diquat.
Spray irrigation was used to test the survival and efficiency of forage grasses as a concentrating mechanism for the inorganic waste elements in leachate from a municipal solid waste sanitary landfill. Lime (0·67 metric tonnes/ha), rock phosphate, and superphosphate (each at 11·2 metric tonnes/ha) were applied in a randomised complete block design to reed canarygrass Phalaris arundinacea L., tall fescue Festuca arundinacea Schreb., cv. ‘Ky 31’, orchardgrass Dactylis glomerata L., bromegrass Bromus inermis Leyss., and bermudagrass Cynodon dactylon (L.) Pers. cvs. ‘Midland’ and ‘Tufcote’. Leachate was applied by overhead rotary sprinklers in weekly 8-h applications from 22 October 1974 to 28 April 1975. The total application averaged about 155 cm.
The decomposition rates of a grass/clover mixture buried in revegetated china clay sand wastes of varying age and management were compared. Rates of weight loss compared favourably with those obtained by other workers on litter decomposition and were generally negatively related to C:N ratio and positively related to organic matter and total nitrogen concentration.
Hexachlorobenzene (HCB) is an organic contaminant with a potential of ecosystem level impacts. Using pine forest microcosms, the transport and effects of HCB on soil processes were studied. HCB-contaminated litter (0, 0·085, 0·730, 7·42 mg/cm3) was applied to replicate soils in filtered, flow-through microcosm systems. Transport of HCB as H14CB and two soil process parameters—CO2 efflux and Ca loss—were monitored. HCB was mobilised from litter-soil systems by both volatisation and leaching. Both process parameters were altered by HCB: CO2 efflux decreased and Ca loss increased in the HCB-treated microcosms.
The effect of nickel on the growth of the freshwater diatom Navicula pelliculosa was determined by noting differences in the growth rate and number of cells present in laboratory cultures exposed to 0, 100, 300 and 600 μg/litre nickel for 14 days. Nickel concentrations as low as 100 μg/litre (1·7 × 10−6M) reduced the population growth rate by 50% and led to decreased 14-day cell numbers. Calculation of the equilibrium composition of the culture medium showed that 99·8% of the total nickel added existed as Ni+2. The occurrence of Ni+2 in the medium was associated with reduced algal growth.
Alcoholic extracts of the tissues of mussels collected from a number of sites were shown to contain chemicals capable of inducing mutation in bacteria and mitotic gene conversion in yeast. For samples derived from one of the genetically positive sites we have demonstrated that the active chemical is predominantly a frameshift mutagen and that the detectable activity was concentrated in the mantle tissue.
The acute LD50 value of DDT in adult summer frogs was only 7·6 mg/kg.The symptoms of poisoning caused by DDT point to nervous damage. The toxicity was further increased by starving. The retention of DDT was followed using (14C)-labelled DDT. It accumulated most in tissues containing fat. Thus the fat body and liver retained much of the DDT while only a very small amount was found in skeletal or heart muscle. In female frogs a large quantity of DDT is stored in the ovary, its large size and high fat content possibly accounting for this phenomenon. Moderate amounts of DDT were found in kidneys and nervous tissue. In addition, an autoradiographical study revealed considerable radioactivity in bones and spleen.
