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In 1997, as part of a national program to determine and map critical loads, a lake survey was carried out in the Republic of Ireland. In total 200 lakes were sampled, which represents approximately 3.3% of the total lake population. The majority of lakes were situated in remote, high-altitude, acid-sensitive areas along the coastal margins of the country. Lake chemistry was dominated by marine inputs. Approximately 50% of the lakes had DOC > 5 mg L−1 due to the presence of organic soils in a large proportion of the catchments. Nonmarine sulfate concentrations were at background levels (< 20 µeq L−1) in 50% of the lakes. Exceedance of critical load was observed in 7% of the sampled lakes (13 lakes). However, there are uncertainties in the critical load calculations due to the interference of sea salts and organic acids; accurate estimation under such conditions requires long-term lake and deposition chemistry.
Acid rain has caused extensive surface water acidification in Sweden since the mid-20th century. Sulfur emissions from fossil-fuel burning and metal production were the main sources of acid deposition. In the public consciousness, acid deposition is strongly associated with the industrial period, in particular the last 50 years. However, studies of lake-water pH development and atmospheric pollution, based on analyses of lake sediment deposits, have shown the importance of a long-term perspective. Here, we present a conceptual argument, using the sediment record, that large-scale atmospheric acid deposition has impacted the environment since at least Medieval times. Sulfur sources were the pre-industrial mining and metal industries that produced silver, lead and other metals from sulfide ores. This early excess sulfur deposition in southern Sweden did not cause surface water acidification; on the contrary, it contributed to alkalization, i.e. increased pH and productivity of the lakes. Suggested mechanisms are that the excess sulfur caused enhanced cation exchange in catchment soils, and that it altered iron-phosphorus cycling in the lakes, which released phosphorus and increased lake productivity.
This paper makes three points relevant to the application of the precautionary principle to the regulation of GMOs. i) The unavoidable arbitrariness in the application of the precautionary principle reflects a deeper epistemological problem affecting scientific analyses of sustainability. This requires understanding the difference between the concepts of “risk”, “uncertainty” and “ignorance”. ii) When dealing with evolutionary processes it is impossible to ban uncertainty and ignorance from scientific models. Hence, traditional risk analysis (probability distributions and exact numerical models) becomes powerless. Other forms of scientific knowledge (general principles or metaphors) may be useful alternatives. iii) The existence of ecological hazards per se should not be used as a reason to stop innovations altogether. However, the precautionary principle entails that scientists move away from the concept of “substantive rationality” (trying to indicate to society optimal solutions) to that of “procedural rationality” (trying to help society to find “satisficing” solutions).
The Kyoto Protocol opens new possibilities for using the biosphere as a carbon sink. Using agro-ecosystems as carbon sinks may be the most appropriate practice from both environmental and socioeconomic points of view. Degraded agro-ecosystems in Africa might benefit significantly from the improved land management that would be part of a carbon sequestration program. There are vast areas of these agro-ecosystems in Africa and their rehabilitation is an urgent matter. We agree with UNEP that there are potentially important synergies to be made between the Convention on Climate Change, the UN Convention to Combat Desertification and the UN Convention on Biodiversity. In this paper, we have investigated the potential for increasing soil carbon content in semiarid agro-ecosystems in the Sudan and found that increasing fallow periods will result in increased soil carbon content and converting marginal agricultural areas to rangeland will restore the carbon levels to 80% of the natural savannah carbon levels in 100 years. The economic gain from a future carbon sequestration program has the potential of a significant contribution to the household economy in these agro-ecosystems.
This paper presents the main findings of a study on health effects of environmental cadmium pollution in China, performed in 1998, i.e. approximately 25 years after the first warnings of such effects were published in Ambio. Forearm bone mineral density (BMD) and renal dysfunction were assessed in population groups exposed to cadmium via rice. Decreased BMD was found in postmenopausal women with elevated urinary cadmium (CdU) or cadmium in blood (CdB) and among men with elevated CdB. Also, clear and statistically significant dose-effect and dose-response relationships were found between CdB or CdU and renal dysfunction (increased excretion of retinol-binding protein). This is the first report of bone effects among Cd-exposed population groups in Asia outside Japan. The report is also of interest since it demonstrates that bone effects, a comparatively severe adverse health effect of Cd, in combination with renal dysfunction, still occurs in environmentally exposed population groups in Asia. Recent reports on bone effects in Cd-exposed population groups in Europe are discussed.
Mercury emissions from the coal smoke is the main source of anthropogenic discharge and mercury pollution in atmosphere. The calculated total amount of mercury emissions of China in 1995 is approximately 213.8 tonnes, which accounts for c. 5% of estimated total global discharge of 4000 tonnes in the same period. From 1978 to 1995, total coal consumption increased fourfold. Based on these data it is estimated that the mercury emissions will increase at a rate of 5% a year, and the predicted emissions will be 273 tonnes in China in 2000. Controlling and solving mercury emissions from coal combustion are among the most important environmental tasks facing China.
This research used knowledge of the indigenous practice of timing nontimber forest product harvest with the full moon to demonstrate that chemicals controlling the decomposition rate of foliage fluctuate with the lunar cycle and may have developed as a result of plant-herbivore interactions. Indigenous knowledge suggests that leaves harvested during the full moon are more durable. Palm leaves harvested during the full moon had higher total C, hemicellulose, complex C and lower Ca concentrations. These chemical changes should make palm leaves less susceptible to herbivory and more durable when harvested during the full moon. This study proposes a mechanism by which plants in the tropics minimize foliage herbivory and influence the decomposition rates of senesced leaves and their durability, especially during the full moon. This research supports the need to use natural life cycles in managing forests and provides a scientific basis for an indigenous community's harvesting practice.
The Oytag valley, about 100 km west of Kashi (Kashgar), is one of the few valleys with forests in the Kunlun Mountains. It underwent severe forest destruction in the late 1950s, and about only one fourth of the natural forest remains. Since the early 1980s, forest conservation and artificial regeneration have been carried out in the valley.