Response to lead pollution: mycorrhizal Pinus sylvestris forms the biomineral pyromorphite in roots and needles

Environmental Science and Pollution Research - The development of mycorrhized pine seedlings grown in the presence of lead was assessed in order to investigate how higher plants can tolerate lead...     

Organochlorine pesticide residues in human milk in Punjab, India

Human milk samples collected from areas having intensive cotton cultivation and sparse cotton cultivation in Punjab (India) were analysed for organochlorine insecticides. Both DDT and HCH were detected in almost all the samples analysed. The average levels of Sigma-DDT and Sigma-HCH residues in samples from cotton-growing areas were significantly higher than in those from areas where cotton is sparsely grown. Residues of Sigma-DDT mainly comprised p,p'-DDT and p,p'-DDE, while those of Sigma-HCH residues were mainly in the form of its beta-isomer. Median values of 0.52 microg g(-1) of Sigma-DDT and 0.19 microg g(-1) of Sigma-HCH in samples of human milk from cotton-growing areas of Punjab (India) were higher than those reported from most other countries in the World.     

Assessment of the impact of rising carbon dioxide and other potential climate changes on vegetation

The projected doubling of current levels of atmospheric carbon dioxide concentration ([CO(2)]) during the next century along with increases in other radiatively active gases have led to predictions of increases in global air temperature and shifts in precipitation patterns. Additionally, stratospheric ozone depletion may result in increased ultraviolet-B (UV-B) radiation incident at the Earth's surface in some areas. Since these changes in the Earth's atmosphere may have profound effects on vegetation, the objectives of this paper are to summarize some of the recent research on plant responses to [CO(2)], temperature and UV-B radiation. Elevated [CO(2)] increases photosynthesis and usually results in increased biomass, and seed yield. The magnitude of these increases and the specific photosynthetic response depends on the plant species, and are strongly influenced by other environmental factors including temperature, light level, and the availability of water and nutrients. While elevated [CO(2)] reduces transpiration and increases photosynthetic water-use efficiency, increasing air temperature can result in greater water use, accelerated plant developmental rate, and shortened growth duration. Experiments on UV-B radiation exposure have demonstrated a wide range of photobiological responses among plants with decreases in photosynthesis and plant growth among more sensitive species. Although a few studies have addressed the interactive effects of [CO(2)] and temperature on plants, information on the effects of UV-B radiation at elevated [CO(2)] is scarce. Since [CO(2)], temperature and UV-B radiation may increase concurrently, more research is needed to determine plant responses to the interactive effects of these environmental variables.     

Does (K+Mg+Ca+P) fertilization lead to recovery of tree health in a nitrogen stressed Quercus rubra L. stand?

In The Netherlands atmospheric deposition of nitrogen compounds to forest ecosystems has been very high for some decades and has led to severe nutritional imbalances in soils as well as in trees. At this moment legislation is not fully in effect with respect to lowering emission/deposition fluxes, particularly of nitrogen. The trees suffer mainly from severe magnesium, potassium and calcium and sometimes phosphorus deficiencies. In this study it was investigated whether fertilization with potassium, magnesium, calcium and phosphorus could prevent a Quercus rubra stand from further decline by restoring the nutritional balance, though the detrimental input of nitrogen compounds still continues. Three fertilization treatments were applied: (i) a standard dose of 1250 kg.ha(-1) containing 60 kg P.ha(-1) (as P2O5), 100 kg K.ha(-1) (as K2O), 80 kg Mg.ha(-1) (as MgO) and 340 kg Ca.ha(-1) (as CaCO3); (ii) two times the standard dose; and (iii) three times the standard dose. Soil solution chemistry showed that the highest dose led to the most significant results: an improved nutrient balance and an increased availability of nutrients. After one growing season following fertilization, the trees looked much healthier and crown density had increased. This revitalization lasted for at least four years. For tree health the mid dose seemed appropriate. After the first growing season potassium is the most mobile nutrient, in the soil and also in the trees, but tended to decrease in the fourth year after fertilization. Magnesium and calcium reached normal values in the leaves after four growing seasons. No obvious effects of phosphorus were found.     

Responses of Gammarus pulex (Amphipoda, Crustacea) to metalliferous effluents: identification of toxic components and the importance of interpopulation variation

This study was designed to evaluate the ability of an in-situ bioassay to assess the impact of complex effluents on freshwaters and to identify toxic components. Reductions in the feeding rate of Gammarus pulex proved to be a sensitive indicator of the impact of metalliferous effluents on receiving water quality. The effluents contained a mixture of five potentially toxic metals. By combining information on feeding rates with bioaccumulation data, two metals, iron and manganese, were identified as the probable toxic agents. Laboratory experiments validated the conclusions reached from the field study and confirmed that iron was a major toxicant. The sensitivities of Gammarus pulex from a metal-contaminated site and a clean site were compared during both the field and laboratory studies. Interpopulation differences in the response of G. pulex to toxicants were detected in the field study but not in the laboratory experiments. Possible reasons for this are discussed.     

Interactions between copper and cadmium modify metal organ distribution in mature tilapia, Oreochromis mossambicus

Sexually mature female tilapia were exposed to sublethal concentrations of waterborne Cu and/or Cd over 6 days, and subsequent body concentrations of these metals were determined in several organs. The results show that the distribution of Cu and Cd was metal and organ specific. This is demonstrated, for example, by the observation that in tilapia, Cu exposure did not result in Cu accumulation in the liver, whereas in the intestinal wall, notably high concentrations of Cu and Cd were measured in metal exposed fish. In addition to single metal exposed fish, we also determined Cu and Cd body distribution in Cu?Cd co-exposed fish. The observed interactions in metal accumulation were most pronounced in the organs of fish exposed to low, environmentally realistic, metal concentrations.     

Air pollution and forest decline in Central Europe

The term 'Waldsterben' was introduced in the early 1980s to describe the progressive death of forests that was believed to be occurring in Central Europe as a result of air pollution. Subsequent surveys and investigations have failed to confirm that forests are dying or are even declining over large areas of Central Europe, defined here as consisting of Germany, Switzerland, southeastern France (Alsace), the Czech Republic, northern Italy and Austria. Foliar injury by air pollutants, together with mortality, has occurred, but is generally restricted to specific locations in the Czech Republic and in eastern Germany, such as the Fichtelgebirge. Where foliar damage has been recorded, it can often be attributed to high concentrations of sulphur dioxide, often acting in combination with other stresses (e.g. frost or insects). Outside areas affected by local sources of pollution, there is little, if any, evidence that the crown condition of trees has been adversely affected by pollution over large areas. Instead, climate appears to have a major effect on the crown condition and growth of trees. Measurements and surveys have revealed a very different picture to that forecasted in the mid-1980s. Growth rates of trees and stands in Central Europe are currently higher than have been recorded at any time in the past; the reasons for this are uncertain, although increases in forest area have not substantially contributed to the observed trends. Although declines in individual species in specific areas have been recorded, past records indicate that these do not represent a new phenomenon. Consequently, the terms 'Waldsterben' (forest deaths) and 'neuartige Waldsch?den' (novel type of forest damages) should not be used in the context of the phenomenon reported in Central Europe in the 1980s. Instead, different problems should be described separately and the term forest decline used only when there is clear evidence of a general deterioration in the condition of all tree species within a forest.     

Metabolism of the herbicide chlortoluron by human cytochrome P450 3A4

Studies were carried out to investigate the metabolism of herbicide chlortoluron in the microsomal fractions and whole cells of Saccharomyces cerevisiae expressing human cytochrome P450 3A4. Both whole cells and microsomal fractions of yeast expressing human cytochrome P450 3A4 exhibited a typical dithionite-reduced, CO-difference absorbance spectrum with maximum absorbance at 448 nm. Chlortoluron produced a type I binding spectrum with cytochrome P450 3A4 with a K_s value of 200 μM. Chlortoluron was metabolised into four metabolites; hydroxylated-N-monodemethylated, hydroxylated ring methylated, N-didemethylated and N-monodemethylated products. Chlortoluron metabolism was absolutely dependent on NADPH and no metabolism was observed in control transformants.     

NATO/CCMS Pilot study workshop on air pollution trarfsport and diffusion over coastal urban areas

The NATO/CCMS Pilot Study “Air pollution transport and diffusion over coastal urban areas” held an international workshop in Athens, 3–5 May 1993. The objective of this workshop was to develop guidelines for it reference experiment in a coastal urban area. It was intended that the guidelines would be sufficiently general that they could be applied to any coastal urban area, but Athens was bome in mind as a suitable candidate location. On the first day of the workshop, invited speakers delivered their lectures on different issues of dispersion in urban coastal areas. The second day was devoted to discussions in working groups focusing on key issues, such as, emissions' inventory, meteorological measurements, surface pollutant concentration measurements, aircraft measurements, remote sensing and model evaluation. On the final half-day the rapporteur from each working group reported on its work. Their reports are briefly summarized in the present paper.     

Ruminant uptake of nickel and other elements from industrial air pollution in the Norwegian-Russian border area

Concentrations of the elements aluminium, arsenic, cadmium, chromium, cobalt, copper, lead, mercury, nickel, selenium and zinc in liver, and of nickel in kidneys, were studied in reindeer, moose and sheep from South Varanger in eastern Finnmark and comparable districts in western Finnmark, Norway. The study included samples from 31 reindeer, 10 moose and 10 sheep from Jarfjord (South Varanger); 31 reindeer, 27 moose and 15 sheep from Pasvik (South Varanger); and 40 reindeer, 16 moose and 15 sheep from western Finnmark. Levels of arsenic, copper, nickel and selenium were much higher in reindeer from one or both areas in South Varanger than in reindeer from western Finnmark. Levels of chromium, cobalt and zinc were also significantly higher in South Varanger reindeer than in reindeer from the reference area. Within South Varanger the highest levels of these elements were invariably found in the Jarfjord area. For the other elements studied hepatic levels in South Varanger were similar to or lower than in western Finnmark. Also in moose, higher levels of nickel and of selenium (Jarfjord only) were found in the South Varanger samples than in samples from western Finnmark. In sheep, on the other hand, levels in South Varanger samples were similar to levels in western Finnmark for all the elements studied. Comparing the results with reports on pollution of air and vegetation, it was concluded that for all the elements showing higher levels in reindeer and moose from South Varanger compared to the reference areas, the effect most probably was a result of atmospheric transport of industrial pollution from the nearby Russian towns Nikel and Zapoljarnij. The geographical and interspecies differences within the South Varanger samples support this conclusion.