Assessment Tools for Urban Catchments: Defining Observable Biological Potential1

Abstract: Urbanization represents a strong and increasingly more prevalent impact on stream quality worldwide. One of the characteristic effects of increased urbanization is a consistent decline in biological stream condition. The characterization of this biological degradation with increasing urbanization presents a number of advantages for the study and management of urban streams and catchments. In this paper, the limitation of biological condition with urbanization, called observed biological potential, is characterized. Using an urban intensity index and a biological index developed specifically for urban systems in the Baltimore, Maryland; Cleveland, Ohio; and San Jose, California regions, two principal techniques were compared (quantile regression and bin regression) to define observed biological potential along urban gradients. Quantile regression was selected as the preferable tool for describing observed biological potential given the consistency with which it can be applied and its statistical efficiency, however, bin quantile regression performed similarly. Having identified a numeric approximation of observed biological potential, two methods for identifying factors related to distance from potential as a way of identifying critical environmental factors affecting biological condition in urban areas were explored. The results of this work can be used for identifying benchmarks for urban stream biological condition, identifying limiting catchment characteristics, and prioritizing urban stream management efforts.     

Choosing a Food Future: Differentiating Among Alternative Food Options

This article examines the diversity of food networks that fit within the alternative food system of the United States. While farmers’ markets, community supported agriculture schemes, and corporate organic food markets all fit within the alternative food system, they differ greatly in the conventions and beliefs that they represent. The alternative food system has divided into two movements: corporate, weak alternative food networks; and local, strong alternative food networks. The weak corporate version focuses on protecting the environment; however, it neglects issues concerning labor standards, animal welfare, rural communities, small-scale farmers, and human health. Local, strong alternative food networks not only assure environmental protection, but they also address the issues that weak alternatives neglect. Using three case studies from the Washington, D.C. metro area, the author explains that strong alternative food networks are better suited to create social and political change because they challenge the foundations of the conventional food system: standardized and generic products, price-based competition, consolidated power, and global scale. To affect true social and political change in the United States, the author recommends supporting strong alternative food networks by creating the requisite cultural and political space for them to succeed.     

Modeling the Hydrology of Climate Change in California’s Sierra Nevada for Subwatershed Scale Adaptation1

Young, Charles A., Marisa I. Escobar‐Arias, Martha Fernandes, Brian Joyce, Michael Kiparsky, Jeffrey F. Mount, Vishal K. Mehta, David Purkey, Joshua H. Viers, and David Yates, 2009. Modeling the Hydrology of Climate Change in California’s Sierra Nevada for Subwatershed Scale Adaptation. Journal of the American Water Resources Association (JAWRA) 45(6):1409‐1423. Abstract: The rainfall‐runoff model presented in this study represents the hydrology of 15 major watersheds of the Sierra Nevada in California as the backbone of a planning tool for water resources analysis including climate change studies. Our model implementation documents potential changes in hydrologic metrics such as snowpack and the initiation of snowmelt at a finer resolution than previous studies, in accordance with the needs of watershed‐level planning decisions. Calibration was performed with a sequence of steps focusing sequentially on parameters of land cover, snow accumulation and melt, and water capacity and hydraulic conductivity of soil horizons. An assessment of the calibrated streamflows using goodness of fit statistics indicate that the model robustly represents major features of weekly average flows of the historical 1980‐2001 time series. Runs of the model for climate warming scenarios with fixed increases of 2°C, 4°C, and 6°C for the spatial domain were used to analyze changes in snow accumulation and runoff timing. The results indicated a reduction in snowmelt volume that was largest in the 1,750‐2,750 m elevation range. In addition, the runoff center of mass shifted to earlier dates and this shift was non‐uniformly distributed throughout the Sierra Nevada. Because the hydrologic model presented here is nested within a water resources planning system, future research can focus on the management and adaptation of the water resources system in the context of climate change.     

Convergence of Culture, Ecology, and Ethics: Management of Feral Swamp Buffalo in Northern Australia

This paper examines the identity of Asian swamp buffalo (Bubalus bubalis) from different value orientations. Buffalo were introduced into Northern (Top End) Australia in the early nineteenth century. A team of transdisciplinary researchers, including an ethicist, has been engaged in field research on feral buffalo in Arnhem Land over the past three years. Using historical documents, literature review, field observations, interviews with key informants, and interaction with the Indigenous land owners, an understanding of the diverse views on the scientific, cultural, and economic significance of buffalo was obtained. While the diverse stakeholders in buffalo exploitation and management have historically delivered divergent value orientations on the nature of the human–buffalo relationship, we argue that over time there is the possibility of values and ethical convergence. Such convergence is possible via transdisciplinary and transcultural agreement on the value stances that constitute the construction of the being or identity of buffalo in the face of the overwhelming need to manage population density and gross numbers.     

Investigations on CO2 storage capacity in saline aquifers—Part 2: Estimation of storage capacity coefficients

Many studies on geological carbon dioxide (CO₂) storage capacity neglect the influence of complex coupled processes which occur during and after the injection of CO₂. Storage capacity is often overestimated since parts of the reservoirs cannot be reached by the CO₂ plume due to gravity segregation and are thus not accessible for storage. This work investigates the effect of reservoir parameters like depth, temperature, absolute and relative permeability, and capillary pressure on the processes during CO₂ injection and thus on estimates of effective storage capacity. The applied statistical characteristics of parameters are based on a large reservoir parameter database. Different measured relative permeability relations are considered. The methodology of estimating storage capacity is discussed. Using numerical 1D and 3D experiments, detailed time-dependent storage capacity estimates are derived. With respect to the concept developed in this work, it is possible to estimate effective CO₂ storage capacity in saline aquifers. It is shown that effective CO₂ mass stored in the reservoir varies by a factor of 20 for the reservoir setups considered. A high influence of the relative permeability relation on storage capacity is shown.     

Assessment of total urban metabolism and metabolic inefficiency in an Irish city-region

This paper aims to measure product and waste flows in an Irish city-region using the principles of metabolism and mass balance. An empirical indicator to measure resource efficiency, using a ratio of waste disposal as a function of product consumption, was developed and it was found that total materials metabolic inefficiency fell by 31% from 0.13 in 1996 to 0.09 in 2002. The paper concludes by analyzing the strengths and weaknesses of this indicator and its potential application in the field of sustainable consumption and resource efficiency as well as making suggestions to improve and strengthen the indicator.     

Model-based prediction of long-term leaching of contaminants from secondary materials in road constructions and noise protection dams

In this study, contaminant leaching from three different secondary materials (demolition waste, municipal solid waste incineration ash, and blast furnace slag) to groundwater is assessed by numerical modeling. Reactive transport simulations for a noise protection dam and a road dam (a typical German autobahn), in which secondary materials are reused as base layers, were performed to predict the breakthrough of a conservative tracer (i.e., a salt) and sorbing contaminants (e.g., PAHs like naphthalene and phenanthrene or heavy metals) at the groundwater table. The dam constructions have a composite architecture with soil covers in inclined layers and distinct contrasts in the unsaturated hydraulic properties of the used materials. Capillary barrier effects result in strong spatial variabilities of flow and transport velocities. Contaminant breakthrough curves at the groundwater table show significant tailing due to slow sorption kinetics and a wide distribution of travel times. While conservative tracer breakthrough depends primarily on subsoil hydraulic properties, equilibrium distribution coefficients and sorption kinetics represent additional controlling factors for contaminant spreading. Hence, the three secondary materials show pronounced differences in the temporal development of leached contaminant concentrations with consequences for breakthrough times and peak concentrations at the groundwater table. Significant concentration reductions due to dispersion occur only if the source concentrations decrease significantly prior to the arrival of the contaminant at the groundwater table. Biodegradation causes significant reduction of breakthrough concentrations only if flow velocities are low.     

Geopolymerisation of silt generated from construction and demolition waste washing plants

Recycling plants that size, sort and wash construction and demolition waste can produce high quality aggregate. However, they also produce up to 80ton per hour of filter cake waste containing fine (<63mum) silt particles that is classified as inert waste and normally landfilled. This research investigated the potential to form geopolymers containing silt, which would allow this problematic waste to be beneficially reused as aggregate. This would significantly improve the economic viability of recycling plants that wash wastes. Silt filter cakes have been collected from a number of aggregate washing plants operating in the UK. These were found to contain similar aluminosilicate crystalline phases. Geopolymer samples were produced using silt and silt mixed with either metakaolin or pulverised fuel ash (PFA). Silt geopolymers cured at room temperature had average 7-day compressive strengths of 18.7MPa, while partial substitution of silt by metakaolin or PFA increased average compressive strengths to 30.5 and 21.9MPa, respectively. Curing specimens for 24h at 105 degrees C resulted in a compressive strength of 39.7MPa and microstructural analysis confirmed the formation of dense materials. These strengths are in excess of those required for materials to be used as aggregate, particularly in unbound applications. The implications of this research for the management of waste silt at construction and demolition waste washing plants are discussed.     

Influences of chemical activators on incinerator bottom ash

This research has applied different chemical activators to mechanically and thermally treated fine fraction (<14 mm) of incinerator bottom ash (IBA), in order to investigate the influences of chemical activators on this new pozzolanic material. IBA has been milled and thermally treated at 800 degrees C (TIBA). The TIBA produced was blended with Ca(OH)(2) and evaluated for setting time, reactivity and compressive strength after the addition of 0.0565 mole of Na(2)SO(4), K(2)SO(4), Na(2)CO(3), K(2)CO(3), NaOH, KOH and CaCl(2) into 100g of binder (TIBA+Ca(OH)(2)). The microstructures of activated IBA and hydrated samples have been characterized by X-ray diffraction (XRD) and thermogravimetry (TG) analysis. Thermal treatment is found to produce gehlenite (Ca(2)Al(2)SiO(7)), wollastonite (CaSiO(3)) and mayenite (Ca(12)Al(14)O(33)) phases. The thermally treated IBA samples are significantly more reactive than the milled IBA. The addition of Na(2)CO(3) can increase the compressive strength and calcium hydroxide consumption at 28-day curing ages. However, the addition of Na(2)SO(4), K(2)SO(4), K(2)CO(3), NaOH and KOH reduces the strength and hydration reaction. Moreover, these chemicals produce more porous samples due to increased generation of hydrogen gas. The addition of CaCl(2) has a negative effect on the hydration of TIBA samples. Calcium aluminium oxide carbonate sulphide hydrate (Ca(4)Al(2)O(6)(CO(3))(0.67)(SO(3))(0.33)(H(2)O)(11)) is the main hydration product in the samples with activated IBA, except for the sample containing CaCl(2).     

Municipal solid waste management in Rasht City, Iran

Pollution and health risks generated by improper solid waste management are important issues concerning environmental management in developing countries. In most cities, the use of open dumps is common for the disposal of wastes, resulting in soil and water resource contamination by leachate in addition to odors and fires. Solid waste management infrastructure and services in developing countries are far from achieving basic standards in terms of hygiene and efficient collection and disposal. This paper presents an overview of current municipal solid waste management in Rasht city, Gilan Province, Iran, and provides recommendations for system improvement. The collected data of different MSW functional elements were based on data from questionnaires, visual observations of the authors, available reports and several interviews and meetings with responsible persons. Due to an increase in population and changes in lifestyle, the quantity and quality of MSW in Rasht city has changed. Lack of resources, infrastructure, suitable planning, leadership, and public awareness are the main challenges of MSW management of Rasht city. However, the present situation of solid waste management in this city, which generates more than 400tons/d, has been improved since the establishment of an organization responsible only for solid waste management. Source separation of wastes and construction of a composting plant are the two main activities of the Rasht Municipality in recent years.