Curriculum Development in Environmental Science: A Case Study on Paradigm and Institutions

/ The case of "Environment and Development" at Leiden University, the Netherlands, offers an example of developing a new environmental science curriculum in a conservative, disciplines-oriented university context. The core of this history is the long-term struggle of environmental science to evolve from the level of doing applied interdisciplinary studies and establish itself as a distinct body of knowledge with its own theory level, i.e., a discipline of its own. The struggle itself as well as its final outcome, a "bidisciplinary" curriculum in which both environmental science and one social science are expressed as disciplines (hence not environmental science as a mere "field of application") may be of value in other "classical" universities, too. KEY WORDS: Environmental science; Curriculum; Interdisciplinarity; Universities     

Lichens as indicators for air quality

Indication depends on the existence of a known relationship between the possibilities for existence of the lichens and the quality of their surroundings. These possibilities may be read from the parameters such as: distribution patterns of species, species numbers, physiological and morphological aspects. This is illustrated by examples with emphasis on: choice of parameters, interaction between several factors, comparison of lichens with other organisms and evaluation of the use of lichens as indicators.     

Aluminium: The Need for a Re-Evaluation of Its Toxicity and Solubility in Mature Forest Stands

Aluminium (Al) is a key element in critical loadcalculations for forest. Here, we argue for re-evaluating theimportance of Al. Effects of two levels of enhanced Alconcentrations and lowered Ca:Al ratios in the soil solutionin a field manipulation experiment in a mature spruce stand(1996–1999) on tree vitality parameters were tested. Inaddition, Al solubility controls were tested. Various loads ofAl were added to forest plots by means of an irrigationsystem. Potentially toxic Al concentrations and criticalratios of Ca to inorganic Al were established. The ratio of Cato total Al was not a suitable indicator for unfavourableconditions for plant growth. No significant effects on crowncondition, tree growth and fine root production were observedafter three years of treatment. In 1999, foliar Mg content inthe highest Al addition treatment had declined significantly.This agreed with the known response to Al stress of seedlingsin nutrient solution experiments. No support was found forusing the chemical criterion Ca:Al ratio in soil solution,foliar and root tissue as an indicator for forest damage dueto acidification. Al solubility was considerably lower thanimplied by the assumption of equilibrium with gibbsite,particularly in the root zone. The gibbsite equilibrium iscommonly used in critical load models. Substitution of thegibbsite equilibrium with an Al-organic matter complexationmodel to describe Al solubility in soil water may have largeconsequences for calculation of critical loads. The resultsindicate that critical load maps for forests should bereconsidered.     

An analysis of the environmental pressure exerted by the eucalyptus-based kraft pulp industry in Thailand

The study reported here focuses on the environmental pressure exerted by large-scale eucalyptus-based kraft pulp industry in Thailand. The objective of this study was to identify the most important sources of greenhouse gases, acidifying and eutrophying compounds and tropospheric ozone precursors, human toxicity compounds and solid waste associated with the kraft pulp industry. To this end, we performed an environmental systems analysis of the kraft pulp industry system in which we distinguished between two subsystems: the eucalyptus forestry subsystem and the kraft pulp production subsystem. The results indicate that the environmental pressure is caused by the kraft pulp production subsystem rather than by the eucalyptus forestry one. The chemical recovery unit was found to be the most important source of carbon dioxide (CO₂) and sulfur dioxide (SO₂) and responsible for more than one-half of the emissions of greenhouse gases and acidifying compounds from eucalyptus-based kraft pulp production in Thailand. Biomass combustion in the energy gene ration unit is an important source of nitrogen oxide (NO _x ) and carbon monoxide (CO) which in turn are responsible for over 50% of the emissions of tropospheric ozone precursors. About 73% of the eutrophication is caused by biological aerobic wastewater treatment emitting phosphorus (P). With respect to the eucalyptus forestry, only fertilizer use in eucalyptus plantations is a relevant source of pollution through the emission of nitrous oxide (N₂O) and phosphate (PO ₄ ³⁻ ).     

Levels, profile and pattern of PCDDs and PCDFs in samples related to the production and use of chlorine

Analyses of sludge from graphite electrodes used in the chloralkali process show total levels of PCDFs as high as 650000 pg/g sludge. The levels of tetra-, penta-and hexaCDFs were found to be approximately the same. The levels for the corresponding PCDDs were below the detection level. The dominating congeners within each group are the toxic 2,3,7,8-substituted PCDFs at levels of 340000 pg/g, This typical pattern, called the “chloralkali pattern” can also be found in soil samples taken at another chloralkali plant. The typical pattern can also be identified in a solution of ferric chloride. Traces of “chloralkali pattern” are identified in a sludge sample from the drinking water purification plant, the source for PCDFs in the sludge is unknown.     

Projected stream water fluxes of NO3 and total organic carbon from the Storgama headwater catchment, Norway, under climate change and reduced acid deposition

Fluctuations in the 20-year record of nitrate (NO3) and total organic carbon (TOC) concentrations and fluxes in runoff at the small headwater catchment Storgama, southern Norway, were related to climate and acid deposition. The long-term decline in NO3 related to reduced NO3 deposition and increased winter discharge, whereas the long-term increase in TOC related to reduced sulfur deposition. Multiple regression models describing long-term trends and seasonal variability in these records were used to project future concentrations given scenarios of climate change and acid deposition. All scenarios indicated reduced NO3 fluxes and increased TOC fluxes; the largest projected changes for the period 2071-2100 were -86% and +24%, respectively. Uncertainties are that the predicted future temperatures are considerably higher than the historical record. Also, nonlinear responses of ecosystem processes (nitrogen [N] mineralization) to temperature, N-enrichment of soils, and step-changes in environmental conditions may affect future leaching of carbon and N.     

Effect of climate change on fluxes of nitrogen from the Tovdal River basin, Norway, to adjoining marine areas

The mass transport model TEOTIL was used to project nitrate (NO3) fluxes from the Tovdal River basin, southernmost Norway, given four scenarios of climate change. Forests, uplands, and open water currently account for 90% of the NO3 flux. Climate scenarios for 2071-2100 suggest increased temperature by 2-4 degrees C and precipitation by 3-11%. Climate experiments and long-term monitoring were used to estimate future rates of nitrogen (N) leaching. More water will run through the terrestrial catchments during the winter but less will run in the spring. The annual NO3 flux from the Tovdal River to the adjoining Topdalsfjord is projected to remain unchanged, but with more NO3 delivered in the winter and less in the spring. Algal blooms in coastal waters can be expected to occur earlier in the year. Major sources of uncertainty are in the long-term fate of N stored in soil organic matter and the impacts of forest management.     

Climate adaptation of interconnected infrastructures: a framework for supporting governance

Infrastructures are critical for human society, but vulnerable to climate change. The current body of research on infrastructure adaptation does not adequately account for the interconnectedness of infrastructures, both internally and with one another. We take a step toward addressing this gap through the introduction of a framework for infrastructure adaptation that conceptualizes infrastructures as complex socio-technical “systems of systems” embedded in a changing natural environment. We demonstrate the use of this framework by structuring potential climate change impacts and identifying adaptation options for a preliminary set of cases—road, electricity and drinking water infrastructures. By helping to clarify the relationships between impacts at different levels, we find that the framework facilitates the identification of key nodes in the web of possible impacts and helps in the identification of particularly nocuous weather conditions. We also explore how the framework may be applied more comprehensively to facilitate adaptation governance. We suggest that it may help to ensure that the mental models of stakeholders and the quantitative models of researchers incorporate the essential aspects of interacting climate and infrastructure systems. Further research is necessary to test the framework in these contexts and to determine when and where its application may be most beneficial.     

Relationships between river sediment characteristics and trace metal concentrations in tubificid worms and chironomid larvae

Surficial sediments, midge larvae (Chironomidae, Diptera) and tubificid worms (Tubificidae, Oligochaeta) were collected at 65 sampling sites located in four different river basins in Flanders (Belgium). Concentrations of the trace metals Cu, Zn, Cd and Pb were measured in organisms and sediments by atomic absorption spectrophotometry. Sediments were subjected to a simultaneous extraction scheme to identify trace metal partitioning among various geochemical phases. Three geochemical characteristics of the sediment were analysed; Total Organic Carbon (TOC), Fe oxides and Mn oxides. Non-linear regression models were constructed to determine the relative importance of the different sediment factors contributing to the variation in metal accumulation by the tubificid worms and chironomids. Generally, the amount of variation that could be explained by these models was limited, with coefficients of determination ranging from 0.05 to 0.66. In most cases, metal levels in organisms were positively related to the easily reducible and reducible metal fractions, and negatively related to the TOC and Fe sediment content. The correlations between metal concentrations in tubificid worms and chrinomid larvae were also rather poor, with coefficients of determinations ranging from 0.01 to 0.52. This indicates that understanding the chemistry of the environment does not suffice to predict the concentrations in organisms. Differences in the structural and functional organisation of the organisms, which among others determine the route of exposure, are at least equally important causes of variability in metal availability and accumulation.     

Seasonal variations in nitrogen-fixation (acetylene reduction) and sulphate-reduction rates in the rhizosphere of Zostera noltii: nitrogen fixation by sulphate-reducing bacteria

Nitrogen-fixation (acetylene reduction) rates were measured over an annual cycle in meadows of the seagrass Zostera noltii Hornem in the Bassin d'Arcachon, south-west France, between March 1994 and February 1995, using both slurry and whole-core techniques. Measured rates using the slurry technique consistently overestimated those determined on whole cores, probably due to the release of labile organic carbon sources as a result of root damage during preparation of the slurries. Thus, the whole-core technique may provide a more accurate estimate of in situ activity, since disturbance of physicochemical gradients of oxygen, sulphide, nutrients and the relationship between the plant roots and the rhizosphere microflora is minimised. Rates measured by the whole-core method were 1.8- to 4-fold greater (dependent upon season) in the light than those measured during dark incubations, indicating that organic carbon diffusing from the plant roots during photosynthesis was an important factor in regulating nitrogen fixation in the rhizosphere. Additions of sodium molybdate, a specific inhibitor of sulphate-reducing bacteria (SRB) inhibited acetylene-reduction activity by >80% as measured by both the slurry and whole-core techniques throughout the year, inferring that SRB were the dominant component of the nitrogen-fixing microflora. A mutualistic relationship between Z. noltii and nitrogen-fixing SRB in the rhizosphere, based on the exchange of organic carbon and fixed nitrogen is proposed. Acetylene- and sulphate-reduction rates showed distinct summer peaks which correlated with a reduced availability of ammonium in the sediment and the annual growth cycle of Z. noltii in the basin. Overall, these data indicate that acetylene reduction (nitrogen fixation) activity in the rhizosphere of Z. noltii was regulated both by the availability of organic carbon from the plant roots and maintenance of a low NH ₄ ⁺ concentration in the vicinity of the plant roots due to efficient assimilation of NH ₄ ⁺ by Z. noltii during the growth season. Nitrogenfixation rates determined from acetylene-reduction rates measured using the whole-core technique ranged from 0.1 to 7.3 mg N m^-2d^-1, depending on season, and were calculated to contribute between 0.4 and 1.1 g N m^-2yr^-1, or 6.3 to 12% of the annual fixed nitrogen requirement of Z. noltii.