Tolerance of calluna vulgaris and peatland plant communities to sulphuric acid deposition

Critical loads offer a unique way of evaluating impacts of acid deposition by quantifying environmental sensitivity. The critical loads of acidity for UK peat soils have been based upon an arbitrary reduction in pH of 0.2 units. This chemical shift needs to be better related to adverse effects on sensitive biological receptors. It is known that effective precipitation pH equates closely to soil solution pH, and the latter is directly linkable to biotic effects of pH change. On continuation of a long-term experiment assessing impacts of simulated acid rain on peat microcosms in a realistic outdoor environment, Calluna vulgaris continued to flourish at acid deposition loads well above the existing critical load. Calluna plants were harvested and analysed, and acid deposition treatments to the microcosms continued to allow natural vegetation to regenerate. A diverse mixture of moorland plants and bryophytes established at acidity treatments well above the existing critical load, and only a very high acid load resulted in no natural regeneration. A critical effective rain pH value of 3.6 is suggested as a basis for setting critical loads. At this pH, Calluna grows well, and a healthy diverse vegetation community re-establishes when harvested. It is suggested that the peat critical load should be set at the acid load that, at any specific site, would result in a mean effective precipitation pH of 3.6.     

Working Life Across Cultures: “Work Life 2000: Quality in Work” and Occupational Health Education in Developing Countries

The article reflects on the changing world of work, and the challenges presented to both occupational health and occupational health education. We draw on the 63 preparatory workshops and the international conference in the “Work Life 2000: Quality in Work” program, an initiative of the Swedish Presidency of the European Union. The International Commission on Occupational Health is introduced, with particular concentration on a current practical project initiated by the Department of Health in South Africa, intended to lead to a set of projects, networking for occupational health education in developing countries. The practical initiatives cast light on a new set of issues that arise when occupational health and safety crosses cultural barriers, and previously separate comparative cases are linked.