Fast increases in urban sewage inputs to rivers of Indonesia

We present estimates for nitrogen (N) and phosphorus (P) sewage inputs to 19 Indonesian rivers for 1970–2050. Future trends are based on the four scenarios of the Millennium Ecosystem Assessment. Our results indicate a rapid increase in N and P pollution from sewage over time. In 1970, N and P inputs to rivers were low because not many households were connected to sewage systems discharging to rivers. Sewage connection is increasing over time. As a result, N and P inputs to rivers increase. We calculate that between 2000 and 2050 the N and P inputs increase with a factor of 17–40, depending on the scenario. Important determinants of future N and P sewage inputs are population, economic growth, urbanization, sewage systems development and wastewater treatment. Our calculations are based on an improved model for N and P inputs to rivers, indicating that previous estimates underestimated these inputs considerably.     

Uncertainty analysis in integrated assessment: the users’ perspective

Integrated Assessment (IA) models aim at providing information- and decision-support to complex problems. This paper argues that uncertainty analysis in IA models should be user-driven in order to strengthen science–policy interaction. We suggest an approach to uncertainty analysis that starts with investigating model users’ demands for uncertainty information. These demands are called “uncertainty information needs”. Identifying model users’ uncertainty information needs allows focusing the analysis on those uncertainties which users consider relevant and meaningful. As an illustrative example, we discuss the case of examining users’ uncertainty information needs in the SEAMLESS Integrated Framework (SEAMLESS-IF), an IA model chain for assessing and comparing alternative agricultural and environmental policy options. The most important user group of SEAMLESS-IF are policy experts at the European and national level. Uncertainty information needs of this user group were examined in an interactive process during the development of SEAMLESS-IF and by using a questionnaire. Results indicate that users’ information requirements differed from the uncertainty categories considered most relevant by model developers. In particular, policy experts called for addressing a broader set of uncertainty sources (e.g. model structure and technical model setup). The findings highlight that investigating users’ uncertainty information needs is an essential step towards creating confidence in an IA model and its outcomes. This alone, however, may not be sufficient for effectively implementing a user-oriented uncertainty analysis in such models. As the case study illustrates, it requires to include uncertainty analysis into user participation from the outset of the IA modelling process.     

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⁻ ).     

Nutrient export by rivers to the coastal waters of China: management strategies and future trends

We analyzed past and future trends in river export of dissolved nitrogen (N) and phosphorus (P) to the coastal waters of China, for a selection of rivers, as calculated by the Global NEWS models (Nutrient Export from WaterSheds). Over the period 1970–2000, river export of dissolved nutrients increased considerably, especially of dissolved inorganic N and P. Anthropogenic sources of N and P in rivers have become increasingly important, in particular N and P losses from agriculture. We tested the sensitivity of calculated nutrient export by rivers to changes in selected controlling factors. The calculated export of dissolved N and P is sensitive to changes in hydrology, synthetic fertilizer use and manure excretion in river basins. Changes in sewage inputs have large effects on dissolved inorganic P export. We analyzed future trends up to 2050 for several scenarios to illustrate the combined effects of selected management options. In the Base Scenario, the N and P export by the selected rivers increases considerably between 2000 and 2030. The increase continues from 2030 to 2050 except for DIP. Strategies to reduce N and P export by rivers include changes in agriculture, sewage and energy use. Changes in agriculture have the largest impact on future dissolved N and P river export to the coastal waters of China. The effectiveness of reduction strategies differs between nutrient forms and basins.     

Options to reduce the environmental impact by eucalyptus-based Kraft pulp industry in Thailand: model description

Kraft pulp industry contributes to several environmental problems, including global warming, acidification, eutrophication, smog, toxicity and the production of solid waste. The objective of this study is to identify options to reduce the environmental pressure caused by Kraft pulp industry in Thailand, and to describe a model that quantifies the environmental impact. The model can be used to evaluate the effects of the options on the environmental impact, and the associated costs. The model includes 14 groups of options to reduce emissions and the production of waste.     

Disaggregation of nation-wide dynamic population exposure estimates in The Netherlands: Applications of activity-based transport models

Traditional exposure studies that link concentrations with population data do not always take into account the temporal and spatial variations in both concentrations and population density. In this paper we present an integrated model chain for the determination of nation-wide exposure estimates that incorporates temporally and spatially resolved information about people's location and activities (obtained from an activity-based transport model) and about ambient pollutant concentrations (obtained from a dispersion model). To the best of our knowledge, it is the first time that such an integrated exercise was successfully carried out in a fully operational modus for all models under consideration. The evaluation of population level exposure in The Netherlands to NO₂ at different time-periods, locations, for different subpopulations (gender, socio-economic status) and during different activities (residential, work, transport, shopping) is chosen as a case-study to point out the new features of this methodology. Results demonstrate that, by neglecting people's travel behaviour, total average exposure to NO₂ will be underestimated by 4% and hourly exposure results can be underestimated by more than 30%. A more detailed exposure analysis reveals the intra-day variations in exposure estimates and the presence of large exposure differences between different activities (traffic > work > shopping > home) and between subpopulations (men > women, low socio-economic class > high socio-economic class). This kind of exposure analysis, disaggregated by activities or by subpopulations, per time of day, provides useful insight and information for scientific and policy purposes. It demonstrates that policy measures, aimed at reducing the overall (average) exposure concentration of the population may impact in a different way depending on the time of day or the subgroup considered. From a scientific point of view, this new approach can be used to reduce exposure misclassification.     

Dynamic Cost-Effective Reduction Strategies for Acidification in Europe: An Application to Ireland and the United Kingdom

This paper describes the application of an optimisation model for calculating cost-effective abatement strategies for the reduction of acidification in Europe while taking into account the dynamic character of soil acidification in a number of countries. Environmental constraints are defined in terms of soil quality indicators, e.g., pH, base saturation or the aluminium ion concentration in the soil solution within an optimisation model for transboundary air pollution.We present a case study for Ireland and the United Kingdom. Our results indicate that reduction of sulphur dioxide emission is more cost-effective than that of nitrogen oxides or ammonia. The reduction percentages for sulphur dioxide are highest, for two reasons: (i) marginal sulphur dioxide reduction costs are relatively low compared to marginal reduction costs of nitrogen oxides and ammonia and (ii) sulphur dioxide reduction is more effective in reducing acidification in physical terms than nitrogen oxides or ammonia abatement. Our dynamic analysis shows that a (fast) improvement of soil quality requires high emission reduction levels. These reduction levels are often higher than reduction levels that are typically deduced from the static critical loads approach. Once soil quality targets are reached, in our model, less stringent emission reductions are required to maintain the soil quality at a constant and good target level. Static critical load approaches that ignore dynamic aspects therefore may underestimate the emission reductions needed to achieve predefined soil quality targets.     

Nitrogen and phosphorus inputs to the Black Sea in 1970–2050

Increased nitrogen (N) and phosphorus (P) inputs are major causes of eutrophication in the coastal waters of the Black Sea. The objective of this study is to analyze the past and future trends in river export of nitrogen and phosphorus to the coastal waters of the Black Sea and to assess the associated potential for coastal eutrophication. The Global NEWS-2 (Nutrient Export from WaterSheds) model was used for this purpose. Currently, most eutrophication occurs in the North Black Sea and the Azov Sea. In the future, however, this may change. We analyzed trends up to 2050 on the basis of the Millennium Ecosystem Assessment (MEA) scenarios. The results indicate that nutrient loads in rivers draining into the North Black Sea and the Azov Sea may decrease in the coming decades as a result of agricultural trends and environmental policy. However, in these scenarios, the targets of the Black Sea Convention are not met. In the South Black Sea, there is currently little eutrophication. But this may change because of increases in nutrient inputs from sewage in the future.