19th century London dust-yards: A case study in closed-loop resource efficiency

The material recovery methods used by dust-yards in early 19th century London, England and the conditions that led to their development, success and decline are reported. The overall system developed in response to the market value of constituents of municipal waste, and particularly the high coal ash content of household ‘dust’. The emergence of lucrative markets for ‘soil’ and ‘breeze’ products encouraged dust-contractors to recover effectively 100% of the residual wastes remaining after readily saleable items and materials had been removed by the thriving informal sector. Contracting dust collection to the private sector allowed parishes to keep the streets relatively clean, without the need to develop institutional capacity, and for a period this also generated useful income. The dust-yard system is, therefore, an early example of organised, municipal-wide solid waste management, and also of public–private sector participation. The dust-yard system had been working successfully for more than 50 years before the Public Health Acts of 1848 and 1875, and was thus important in facilitating a relatively smooth transition to an institutionalised, municipally-run solid waste management system in England. The dust-yards can be seen as early precursors of modern materials recycling facilities (MRFs) and mechanical–biological treatment (MBT) plants; however, it must be emphasised that dust-yards operated without any of the environmental and occupational health considerations that are indispensable today. In addition, there are analogies between dust-yards and informal sector recycling systems currently operating in many developing countries.     

Approaches to assess biocover performance on landfills

Methane emissions from active or closed landfills can be reduced by means of methane oxidation enhanced in properly designed landfill covers, known as “biocovers”. Biocovers usually consist of a coarse gas distribution layer to balance gas fluxes placed beneath an appropriate substrate layer. The application of such covers implies use of measurement methods and evaluation approaches, both during the planning stage and throughout the operation of biocovers in order to demonstrate their efficiency. Principally, various techniques, commonly used to monitor landfill surface emissions, can be applied to control biocovers. However, particularly when using engineered materials such as compost substrates, biocovers often feature several altered, specific properties when compared to conventional covers, e.g., respect to gas permeability, physical parameters including water retention capacity and texture, and methane oxidation activity. Therefore, existing measuring methods should be carefully evaluated or even modified prior to application on biocovers. This paper discusses possible strategies to be applied in monitoring biocover functionality. On the basis of experiences derived from investigations and large-scale field trials with compost biocovers in Austria, an assessment approach has been developed. A conceptual draft for monitoring biocover performance and recommendations for practical application are presented.     

Methanotrophs and methanotrophic activity in engineered landfill biocovers

The dynamics and changes in the potential activity and community structure of methanotrophs in landfill covers, as a function of time and depth were investigated. A passive methane oxidation biocover (PMOB-1) was constructed in St-Nicéphore MSW Landfill (Quebec, Canada). The most probable number (MPN) method was used for methanotroph counts, methanotrophic diversity was assessed using denaturing gradient gel electrophoresis (DGGE) fingerprinting of the pmoA gene and the potential CH₄ oxidation rate was determined using soil microcosms. Results of the PMOB-1 were compared with those obtained for the existing landfill cover (silty clay) or a reference soil (RS). During the monitoring period, changes in the number of methanotrophic bacteria in the PMOB-1 exhibited different developmental phases and significant variations with depth. In comparison, no observable changes over time occurred in the number of methanotrophs in the RS. The maximum counts measured in the uppermost layer was 1.5 × 10⁹ cells g dw^?1 for the PMOB-1 and 1.6 × 10⁸ cells g dw^?1 for the RS. No distinct difference was observed in the methanotroph diversity in the PMOB-1 or RS. As expected, the potential methane oxidation rate was higher in the PMOB-1 than in the RS. The maximum potential rates were 441.1 and 76.0 μg CH₄ h^?1g dw^?1 in the PMOB and RS, respectively. From these results, the PMOB was found to be a good technology to enhance methane oxidation, as its performance was clearly better than the starting soil that was present in the landfill site.     

Phytopumping for hydraulic control of an arsenic plume

Phytoremediation, the use of plants for in situ contaminant cleanup, is gaining new appreciation as an aesthetically pleasing, sustainable method that naturally makes use of solar power. Hybrid poplars are widely used because they grow rapidly and have high transpiration rates, making them advantageous for hydraulic control of groundwater. However, the tendency for trees and other vegetation to uptake metals may be a disadvantage in some settings due to potential redistribution of metals from groundwater to the ground surface. Therefore, a pilot test in the upper midwestern United States was implemented to evaluate the applicability of poplars to groundwater withdrawal and metals transport. © 2009 Wiley Periodicals, Inc.     

The response of sea scallop (Placopecten magellanicus) veligers to a weak thermocline in 9-m deep mesocosms

We examined the vertical distributions of scallop (Placopecten magellanicus) veligers in deep (0.6 m diameter, 9.5 m deep) polyethylene mesocosms from December 1991 to January 1992. In the mesocosms temperature stratification varied from 0 to 1.5 °C. Profiles of vertical distribution revealed several repeated patterns. Peaks in veliger numbers often appeared at the water surface and just above the thermocline. Higher density patches were seen below the surface peaks, and revealed the presence of bio-convective cells. Distribution away from these discontinuities was usually even. Distribution of veligers was affected by thermoclines above 1.0 °C. Responses to thermoclines varied with larval age and time of day, and 28 to 30 d veligers passed in both directions through a 1.5 °C thermocline. We conclude that larval behaviour is a major determinant of whether veligers pass through a thermocline. Kinematic viscosity may play a role in perception of temperature changes. Two potential consequences of such behaviour are (1) remaining in more productive upper water layers, where feeding opportunities are enhanced, and (2) increased horizontal transport in the region of the thermocline, which may enhance recruitment. Received: 15 May 1996 / Accepted: 11 May 2000     

Outdoor Weathering Evaluation of Carbon-Black-Filled, Biodegradable Copolyester as Substitute for Traditionally Used, Carbon-Black-Filled, Nonbiodegradable, High-Density Polyethylene Mulch Films

Carbon-black-filled, biodegradable, copolyester mulch film (Eastar®, or EA, Tennessee Eastman, Kingsport, TN) and commercial carbon-black-filled, high-density polyethylene (HDPE) mulch film were exposed for 12 weeks to commercial vegetable crop growing conditions by being placed directly on irrigated soil in the field of the University of Tennessee Alcoa Highway State Agriculture Experiment Station (Knoxville, TN) and by being placed on a plywood exposure rack as described by the American Society of Testing and Materials (ASTM) Standard Test Method 1435: Outdoor Weathering of Plastics. Mechanical properties and weather information were collected in order to evaluate the feasibility of using the newly developed biodegradable EA mulch film to replace the nonbiodegradable HDPE mulch film. Results indicate that the EA mulch film exhibited favorable tensile strength and elongation-at-break during outdoor exposure rack testing and outdoor, in-field, placed directly on the soil, exposure testing, suggesting biodegradable EA could be a substitute for the HDPE nonbiodegradable material.     

Toxicity of waters from two streams to early life stages of brown trout (Salmo trutta f. fario L.), tested under semi-field conditions.

The development of brown trout (Salmo trutta f. fario L.) in water of two differently polluted streams and in a control situation was monitored in order to get insights into the impact of anthropogenic chemical stressors on the reproductive success of this fish species indigenous to both streams. The test streams, situated in the south of Stuttgart, Germany, were the complexly polluted K?rsch stream and the less polluted Kr?henbach stream. Bypass systems connected to the streams and a laboratory control system were used for continuous exposure of early brown trout stages shortly after fertilisation up to the end of the embryonic development. Temperature and oxygen conditions were standardised in all test series in order to minimise unspecific effects. The examined endpoints were: (1) mortality, (2) developmental rate, (3) time course of hatching, (4) malformations, and (5) growth. A retarded development, reduced growth rates and higher mortality rates of K?rsch stream water exposed embryos indicated an embryotoxic potential for the more polluted stream. High infection-related mortality rates of embryos suggested the presence of confounding factors also in the less polluted Kr?henbach stream. In parallel to the exposure experiment, physicochemical and limnochemical parameters as well as concentrations of organic contaminants and heavy metals were monitored. Analytical data confirm the different degrees of pollution of both streams.     

Storage and distribution of trace metals and spheroidal carbonaceous particles (SCPs) from atmospheric deposition in the catchment peats of Lochnagar, Scotland.

Lochnagar is a remote mountain lake to the south-east of the Cairngorm region in Scotland. Its catchment receives anthropogenic trace metals solely from atmospheric deposition. Ten peat cores were taken from the catchment and analysis confirmed that they have been contaminated by trace metals. The peats have an high affinity for trace metals and this results in metal accumulation in the surface peat layers. The formation of trace metal sulphides may also reduce remobilisation. In this way, trace metals derived from atmospheric deposition have been scavenged and accumulated. In contaminated peat layers, 77.4% Hg, 89.6% Pb, 93.4% Cu, 72.4% Zn and 86.5% Cd of the total stored are from anthropogenic sources. The accumulated trace metals in the peats can potentially influence the lake system through erosion. Spheroidal carbonaceous particle (SCP) profiles were used to date the peat cores. By referring to the SCP profiles in the peats and comparing these with the trace metal profiles in the lake sediments, the mobility of trace metals in the catchment peats is confirmed.     

Sampling optimization, at site scale, in contamination monitoring with moss, pine and oak.

With the aim of optimizing protocols for sampling moss, pine and oak for biomonitoring of atmospheric contamination and also for inclusion in an Environmental Specimen Bank, 50 sampling units of each species were collected from the study area for individual analysis. Levels of Ca, Cu, Fe, Hg, Ni, and Zn in the plants were determined and the distributions of the concentrations studied. In moss samples, the concentrations of Cu, Ni and Zn, considered to be trace pollutants in this species, showed highly variable long-normal distributions; in pine and oak samples only Ni concentrations were log-normally distributed. In addition to analytical error, the two main source of error found to be associated with making a collective sample were: (1) not carrying out measurements on individual sampling units; and (2) the number of sampling units collected and the corresponding sources of variation (microspatial, age and interindividual). We recommend that a minimum of 30 sampling units are collected when contamination is suspected.