Science of The Total Environment

We studied the origin of elements of an undisturbed stream basin during the dry season as derived by atmospheric inputs and lithological processes. Α mass balance model was applied taking into account atmospheric (rain and vapor) inputs and their origin from marine aerosol and dust, as well as the contribution of rock mineral weathering and dissolution of soluble salts. The model results were enhanced using element enrichment factors, element ratios and water stable isotopes. Weathering and dissolution of bedrock and soil minerals contributed the main element portions, besides sodium and sulfate that chiefly derived from wet deposition. Vapor was shown to contribute water to inland waters of the basin. However, rain was the main source of elements compared to vapor, with marine aerosol being the only atmospheric chloride source, contributing also over 60 % of atmospheric sodium and magnesium. Silicate derived from mineral weathering (mainly plagioclase and amorphous silica), while soluble salt dissolution contributed the main portions of the rest of major elements. In headwater springs and streams, element concentrations were more affected by atmospheric inputs and silicate mineral weathering was more intense, contrary to lowland waters that were more affected by soluble salt dissolution. Effective self-purification processes were mirrored in low nutrient levels, despite the significant inputs from wet deposition, with rain being more important contributor than vapor for the majority of nutrient species. Relatively high nitrate concentrations in headwaters were attributed to increased mineralization and nitrification, while the downstream nitrate diminishing was due to prevailing denitrification processes. The ultimate goal of this study is to contribute in establishing stream elements' reference conditions using mass balance modeling approaches.

Small islands are vulnerable to climate change, and at the same time contribute to local and global environmental problems with the intensification of tourist activities. Whereas there are many studies on the resource requirements or environmental impacts of small islands, there are few efforts to integrate information that is often analysed separately. Metabolic analysis, beyond quantifying biophysical flows, studies how society transforms these flows to reproduce the identity of the whole. This study applies the Multi-Scale Integrated Analysis of Societal and Ecosystem Metabolism (MuSIASEM) approach, to analyse the environmental and economic performance of different economic activities in the Mediterranean island of Menorca (Spain). The openness of the metabolic system (observed in the dependence on imports) and externalization of environmental impact are illustrated using the examples of the cheese and tourist industry. The results show that a higher economic performance in terms of value added is associated with activities in industry and services with a larger dependence on imports of “external resources” – fuel for transportation, milk for cheese, seasonal workers and “paying capacity” of tourists. This dependence reduces local environmental pressures and also adaptation capacity, since decisions made in Menorca may have limited impact elsewhere. Local agriculture depends less on external resources but it is limited by the low economic productivity of land and labour. An integrated analysis of the relations between metabolic rates and densities of flows in the different compartments of the society provides a holistic picture of sustainability issues and can contribute to decision-making by avoiding partial information.

Rapid urbanization has greatly altered the urban metabolism of material and energy. As a significant part of the infrastructure, urban roads are being rapidly developed worldwide. Quantitative analysis of metabolic processes on urban road systems, especially the scale, composition and spatial distribution of their stocks, could help to assess the resource appropriation and potential environmental impacts, as well as improve urban metabolism models. In this paper, an integrated model, which covered all types of roads, intersection structures and ancillary facilities, was built for calculating the material stocks of urban road systems. Based on a bottom-up method, the total stocks were disassembled into a number of stock parts rather than obtained by input–output data, which provided an approach promoting data availability and inner structure understanding. The combination with GIS enabled the model to tackle the complex structures of road networks and avoid double counting. In the case study of Beijing, the following results are shown: 1) The total stocks for the entire road system reached 159million tons, of which nearly 80% was stored in roads, and 20% in ancillary facilities. 2) Macadam was the largest stock (111million tons), while stone mastic asphalt, polyurethane plastics, and atactic polypropylene accounted for smaller components of the overall system. 3) The stock per unit area of pedestrian overcrossing was higher than that of the other stock units in the entire system, and its steel stocks reached 0.49t/m2, which was 10 times as high as that in interchanges. 4) The high stock areas were mainly distributed in ring-shaped and radial expressways, as well as in major interchanges. 5) Expressways and arterials were excessively emphasized, while minor roads were relatively ignored. However, the variation of cross-sectional thickness in branches and neighborhood roads will have a significant impact on the scale of material stocks in the entire road system.

Hurricanes are complex disturbance systems with significant effects on vegetation and built-up land. This paper summarizes research on the effects and outcomes of hurricanes on Caribbean forests. Twelve effects and outcome topics are presented: sudden and massive tree mortality; delayed patterns of tree mortality; alternative methods of forest regeneration; opportunities for a change in successional direction; high species turnover and opportunities for species change in forests; diversity of age classes; faster biomass and nutrient turnover; species substitutions and changes in turnover time of biomass and nutrients; lower aboveground biomass in mature vegetation; carbon sinks; selective pressure on organisms; and convergence of community structure and organization. Effects of hurricanes on urban systems are also discussed. While there is scientific uncertainty as to whether hurricane frequencies and intensity will change as a result of global climate change, available understanding on the effects and outcomes of hurricanes can be used to anticipate possible effects of either increasing or decreasing hurricane frequency and intensity. Proposed mitigation actions and research priorities can be effective and desirable even if the frequency and intensity of hurricanes remains unchanged.