Grading of Parameters for Urban Tree Inventories by City Officials, Arborists, and Academics Using the Delphi Method

Tree inventories are expensive to conduct and update, so every inventory carried out must be maximized. However, increasing the number of constituent parameters increases the cost of performing and updating the inventory, illustrating the need for careful parameter selection. This article reports the results of a systematic expert rating of tree inventories aiming to quantify the relative importance of each parameter. Using the Delphi method, panels comprising city officials, arborists, and academics rated a total of 148 parameters. The total mean score, the top ranking parameters, which can serve as a guide for decision-making at practical level and for standardization of tree inventories, were: Scientific name of the tree species and genera, Vitality, Coordinates, Hazard class, and Identification number. The study also examined whether the different responsibilities and usage of urban tree databases among organizations and people engaged in urban tree inventories affected their prioritization. The results revealed noticeable dissimilarities in the ranking of parameters between the panels, underlining the need for collaboration between the research community and those commissioning, administrating, and conducting inventories. Only by applying such a transdisciplinary approach to parameter selection can urban tree inventories be strengthened and made more relevant.     

An integrated approach to model the biomagnification of organic pollutants in aquatic food webs of the Yangtze Three Gorges Reservoir ecosystem using adapted pollution scenarios

The impounding of the Three Gorges Reservoir (TGR) at the Yangtze River caused large flooding of urban, industrial, and agricultural areas, and profound land use changes took place. Consequently, substantial amounts of organic and inorganic pollutants were released into the reservoir. Additionally, contaminants and nutrients are entering the reservoir by drift, drainage, and runoff from adjacent agricultural areas as well as from sewage of industry, aquacultures, and households. The main aim of the presented research project is a deeper understanding of the processes that determines the bioaccumulation and biomagnification of organic pollutants, i.e., mainly pesticides, in aquatic food webs under the newly developing conditions of the TGR. The project is part of the Yangtze-Hydro environmental program, financed by the German Ministry of Education and Science. In order to test combinations of environmental factors like nutrients and pollution, we use an integrated modeling approach to study the potential accumulation and biomagnification. We describe the integrative modeling approach and the consecutive adaption of the AQUATOX model, used as modeling framework for ecological risk assessment. As a starting point, pre-calibrated simulations were adapted to Yangtze-specific conditions (regionalization). Two exemplary food webs were developed by a thorough review of the pertinent literature. The first typical for the flowing conditions of the original Yangtze River and the Daning River near the city of Wushan, and the second for the stagnant reservoir characteristics of the aforementioned region that is marked by an intermediate between lake and large river communities of aquatic organisms. In close cooperation with German and Chinese partners of the Yangtze-Hydro Research Association, other site-specific parameters were estimated. The MINIBAT project contributed to the calibration of physicochemical and bathymetric parameters, and the TRANSMIC project delivered hydrodynamic models for water volume and flow velocity conditions. The research questions were firstly focused on the definition of scenarios that could depict representative situations regarding food webs, pollution, and flow conditions in the TGR. The food webs and the abiotic site conditions in the main study area near the city of Wushan that determine the environmental preconditions for the organisms were defined. In our conceptual approach, we used the pesticide propanil as a model substance.     

Life cycle assessment of selective non-catalytic reduction (SNCR) of nitrous oxides in a full-scale municipal solid waste incinerator

Selective non-catalytic reduction (SNCR) of nitrous oxides in a full-scale municipal solid waste incinerator was investigated using LCA. The relationship between NO_x-cleaning and ammonia dosage was measured at the plant. Un-reacted ammonia - the ammonia slip - leaving the flue-gas cleaning system adsorbed to fly-ash or in the effluent of the acidic scrubber was quantified from the stoichiometric reaction of NO_x and ammonia assuming no other reaction products was formed. Of the ammonia slip, 37% was associated with the fly-ash and 63% was in the effluent of the acidic scrubber. Based on NO_x-cleaning efficiency, the fate of the ammonia slip as well as the environmental impact from ammonia production, the potential acidification and nutrient enrichment from NO_x-cleaning was calculated as a function of ammonia dosage. Since the exact fate of the ammonia slip could not be measured directly, a number of scenarios were set up ranging from “best case” with no ammonia from the slip ending up in the environment to “worst case” where all the ammonia slip eventually ended up in the environment and contributed to environmental pollution. In the “best case” scenario the highest ammonia dosage was most beneficial demonstrating that the environmental load associated with ammonia production is of minor importance. In contrast, in a “worst case” scenario” NO_x-cleaning using SNCR is not recommendable at all, since the impacts from the ammonia slip exceed the saved impacts from the NO_x removal. Increased dosage of ammonia for removal of NO_x is recommendable as long as less than 10-20% of the ammonia slip to the effluent of the acidic scrubber ends up in the environment and less than 40% of the slip to the fly-ash ends up in the environment. The study suggests that the actual fate of the ammonia slip is crucial, but since the release of the ammonia may take place during transport and at the facilities that treat the wastewater and treat the fly-ash this factor depends strongly on local conditions and may be hard to determine. Thus, LCA-modeling proved useful in assessing the balance between ammonia dosage and NO_x-removal in flue-gas cleaning from waste incineration.     

Improving the layout of recycling centres by use of lean production principles

There has been increased focus on recycling in Sweden during recent years. This focus can be attributed to external environmental factors such as tougher legislation, but also to the potential gains for raw materials suppliers. Recycling centres are important components in the Swedish total recycling system. Recycling centres are manned facilities for waste collection where visitors can bring, sort and discard worn products as well as large-sized, hazardous, and electrical waste. The aim of this paper was to identify and describe the main flows and layout types at Swedish recycling centres. The aim was also to adapt and apply production theory for designing and managing recycling centre operations. More specifically, this means using lean production principles to help develop guidelines for recycling centre design and efficient control.Empirical data for this research was primarily collected through interviews and questionnaires among both visitors and employees at 16 Swedish recycling centres. Furthermore, adapted observation protocols have been used in order to explore visitor activities. There was also close collaboration with a local recycling centre company, which shared their layout experiences with the researchers in this project.The recycling centres studied had a variety of problems such as queues of visitors, overloading of material and improper sorting. The study shows that in order to decrease the problems, the recycling centres should be designed and managed according to lean production principles, i.e. through choosing more suitable layout choices with visible and linear flows, providing better visitor information, and providing suitable technical equipment. Improvements can be achieved through proper planning of the layout and control of the flow of vehicles, with the result of increased efficiency and capacity, shorter visits, and cleaner waste fractions. The benefits of a lean production mindset include increased visitor capacity, waste flexibility, improved sorting quality, shorter time for visits and improved working conditions.     

How should support for climate-friendly technologies be designed?

Stabilizing global greenhouse gas concentrations at levels to avoid significant climate risks will require massive "decarbonization" of all the major economies over the next few decades, in addition to the reduced emissions from other GHGs and carbon sequestration. Achieving the necessary scale of emissions reductions will require a multifaceted policy effort to support a broad array of technological and behavioral changes. Change on this scale will require sound, well-thought-out strategies. In this article, we outline some core principles, drawn from recent social science research, for guiding the design of clean technology policies, with a focus on energy. The market should be encouraged to make good choices: pricing carbon emissions and other environmental damage, removing distorting subsidies and barriers to competition, and supporting RD&D broadly. More specific policies are required to address particular market failures and barriers. For those technologies identified as being particularly desirable, some narrower RD&D policies are available.     

Morphologie effects of channelization: the case of the Neebing-McIntyre floodway,Thunder Bay,Ontario, Canada

The Neebing-McIntyre floodway in Thunder Bay, Ontario, Canada, has been constructed with a relatively straight and uniform trapezoidal channel, compared with the prechannelized sinuous reaches of the Neebing and the McIntyre rivers. The flow regime of the floodway also contrasts significantly with the prechannelized regime, because of the combination of discharges from these rivers into a new channel and the regulation of flows by a diversion structure. The maximum channel capacity of the floodway is about 284 m³ s^–1 (175-year regional flood), compared with about 40 m³ s^–1 and 60 m³ s^–1, respectively, for the Neebing and the McIntyre. According to regime theories, the construction of a straight and trapezoidal channel has upset the equilibrium of the stream system and therefore should lead to some accelerated erosion and sedimentation processes in the new channel immediately after construction. Erosion potential is particularly high during higher discharge events, when flow velocities are expected to be greater than the prechannelized velocities of the Neebing and the McIntyre. The overall sediment yield of the watershed is low (71t km^–2 yr^–1), compared with other documented watersheds of North America, but the rates of deposition in the floodway are relatively high, mainly due to the backwater effect of Lake Superior. Unless maintained by constant channel work, the floodway will tend to fill up with sediment, until a postconstructional equilibrium is reestablished.     

Emissions from heated indoor dust

Settled indoor dust was collected from a university building, and the fine fraction was heated in the temperature range of 50-250 degrees C. Emissions of compounds were analysed and identified in a system consisting of a thermal desorption unit coupled to a gas chromatograph-mass spectrometer (GC-MS). The heating took place in both an oxidative (air) and an inert (He) atmosphere. The results indicate that oxidation of adsorbed compounds occurred, as well as decomposition of the dust itself. The emission in air started somewhere between 150 and 200 degrees C, with aldehydes and ketones as the main compounds. When heated in the inert atmosphere, semivolatile organic compounds (SVOCs) were emitted at temperatures above 150 degrees C. These compounds were not found in the air system, probably due to oxidation. Based on the obtained results we recommend that the temperature of hot surfaces in indoor environments should be kept below 150 degrees C to avoid oxidation of indoor dust and minimise the emissions.     

A Baumol–Oates approach to solid waste taxation

A national Baumol–Oates tax on waste in Denmark helped achieve a reduction of 26% in net solid waste from 1987 to 1998. The tax, which is levied per ton of waste, was particularly effective as regards the heavier waste streams such as construction waste and garden waste. When it comes to industrial and commercial waste, there are indications that the waste tax is not sufficiently significant to induce changes in behavior, and that except for very waste-intensive enterprises, companies do not seem to be very price sensitive. For household waste, the impact of the tax can be improved where tariffs for garbage collection are weight based, rather than per unit. However, the waste sector is an area in which the price signals are modified and filtered by institutionalized practices in municipal administration, and in which true-cost pricing is not easy to achieve. Hence, the rational choice assumption of environmental economics needs to be supplemented by an institutional dimension to interpret responses to environmental taxes correctly. Received: July 13, 2001 / Accepted: October 2, 2001     

Preface

Water, Air, &; Soil Pollution: Focus -     

Landscape changes in agrarian landscapes in the 1990s: the interaction between farmers and the farmed landscape. A case study from Jutland, Denmark

Recent landscape changes in a farmed landscape are analysed and related to farm and farmer characteristics. It is assumed that farm and farmer characteristics serve as mediators of large scale or macro driving forces of change-in the present case, a changing farming context including demands for a more environmentally friendly farming practise and a reduced output. The results are based on multivariate analyses of data collected from structured interviews of 160 farmers in a case study area, in central Jutland, measuring 5000 ha. The analysis shows that farmers are highly involved in landscape changes. The investigated landscape changes include creation and removal of landscape elements as well as certain management changes. The most common activity was creation of elements: hedgerows, small woodlands and conversion of rotational arable land to permanent grassland, whereas removal of elements, mainly hedgerows and semi-natural grasslands, were seen less frequently. Management changes like abandonment of permanent grassland were widespread. The results indicate a general extensification of the land use and the authors interpret the results partly as an indication of a change from productivism to a more multifunctional agricultural regime. The observed landscape changes at the farm level show a low, but structured relationship with the current farm and farmer characteristics, meaning that landscape changes were undertaken by various farmers and on various farms. On a general level, however, the age of the farmer and the duration of farm ownership seem to have a major influence on the landscape changes.