Polymers as Solid Waste in Municipal Landfills

Abstract

Synthetic polymers reach municipal landfills as components of products such as waste household paints, packaging films, storage containers, carpet fibers, and absorbent sanitary products. Some polymers in consumer products that reach landfills are designed to photodegrade or biodegrade. This article examines the significance of degradable polymers in management of solid waste in municipal landfills. Most landfills are not designed to photodegrade or biodegrade solid waste. Landfill disposal of stable polymers such as polyacrylics and polyethylenes is not associated with significant polymer degradation or mobility. Stability to photodegradation and biodegradation is an advantage when municipal landfills are used for disposal of polymer products as solid waste. Use of landfill disposal can be a responsible means to manage polymer waste and can be part of an overall waste management plan which includes source reduction, recycling, reuse, composting, and waste-to-energy incineration.     

An Assessment of the Economic Effects of Ozone on U.S. Agriculture

Past attempts to measure the economic consequences of ozone on agriculture have been based on limited plant science information. This paper reports on an economic assessment of ozone on U.S. agriculture using recent crop response data from the National Crop Loss Assessment Network (NCLAN). The results are derived from a U.S. agricultural sector model that includes major crop and livestock production as well as domestic consumption, livestock feeding and export uses. The economic effects of four hypothetical ambient ozone levels are investigated. The analysis Indicates that the benefits to society of moderate (25%) ozone reductions are approximately $1.7 billion. A 25% Increase in ozone pollution results in costs (negative benefits) of $2.1 billion. These estimates do not reflect compliance costs of achieving the ozone changes and hence are not net benefits.     

Polycyclic aromatic compounds in Northwest Atlantic COD (Gadus morhua)

Twenty-seven polycyclic aromatic compounds (PAC) including polycyclic aromatic hydrocarbons (PAH) and polycyclic aromatic sulphur heterocycles were analysed in muscle, liver and ovaries of cod (Gadus morhua) from the Northwest Atlantic. These PAC include the 16 PAH priority pollutants (EPA recommendation), alkylated naphthalenes, phenanthrene-anthracenes as well as dibenzothiophenes (DBT). Aromatics were undetectable in muscle. One of the analysed PAC was detected in one ovary and six in another ovary sample. Liver samples contained between 1 and 9 PAC. Of the parental PAH, only acenapthene (18 ng/g, dry weight), fluorene (28 ng/g) and chrysene (22 ng/g) were detected once each in two liver samples, while fluorene (72 ng/g) was detected once in one of the ovaries. C-2 DBT was the major component in ovaries and liver (8-86 ng/g), while C-3 and C-4 alkylated phenanthrene-anthracene (12-78 ng/g) were the next major components detected in the liver samples. This is the first detailed study of PAH and PAC in finfish from the Northwest Atlantic.     

Do vesicle cells of the red alga Asparagopsis (Falkenbergia stage) play a role in bromocarbon production?

The Rhodophyceae (red algae) are an established source of volatile halocarbons in the marine environment. Some species in the Bonnemaisoniaceae have been reported to contain large amounts of halogens in structures referred to as vesicle cells, suggesting involvement of these specialised cells in the production of halocarbons. We have investigated the role of vesicle cells in the accumulation and metabolism of bromide in an isolate of the red macroalga Asparagopsis (Falkenbergia stage), a species known to release bromocarbons. Studies of laboratory-cultivated alga, using light microscopy, revealed a requirement of bromide for both the maintenance and formation of vesicle cells. Incubation of the alga in culture media with bromide concentrations below 64 mgl(-1) (the concentration of Br(-) in seawater) resulted in a decrease in the proportion of vesicle cells to pericentral cells. The abundance of vesicle cells was correlated with bromide concentration below this level. Induction of vesicle cell formation in cultures of Falkenbergia occurred at concentrations as low as 8 mgl(-1), with the abundance of vesicle cells increasing with bromide concentration up to around 100 mgl(-1). Further studies revealed a positive correlation between the abundance of vesicle cells and dibromomethane and bromoform production. Interestingly, however, whilst dibromomethane production was stimulated by the presence of bromide in the culture media, bromoform release remained unaffected suggesting that the two compounds are formed by different mechanisms.     

Downscaling and visioning of mountain snow packs and other climate change implications in North Vancouver, British Columbia

This paper provides an overview of a collaborative study on visualizing climate change at the local scale. A conceptual framework has been developed, in which local scenarios and visualizations of climate change impacts and response were created to facilitate local dialogue on incorporating climate change into long-term planning and implementation of community development decisions. As part of a larger effort to generate a new integrated participatory visioning process, this paper describes a case study of the District of North Vancouver which created visualizations of changing mountain snow and landscape conditions, and provides new insights on issues and dilemmas in using realistic landscape visualizations to depict scientific modelling projections, local responses to climate change, and uncertainty. Results from this study suggest that the visualizations, and subsequent dialogue sessions, did influence emotional response to climate change as well as self-assessed understanding of adaptation and mitigation response options. However, there is a need to test this visioning process with larger heterogeneous groups of participants in order to better assess its effectiveness in enabling dialogue on local responses to climate change.     

Using environmental and geographic data to optimize ex situ collections and preserve evolutionary potential

Maintenance of biodiversity through seed banks and botanical gardens, where the wealth of species’ genetic variation may be preserved ex situ, is a major goal of conservation. However, challenges can persist in optimizing ex situ collections if trade-offs exist among cost, effort, and conserving species evolutionary potential, particularly when genetic data are not available. We evaluated the genetic consequences of population preservation informed by geographic (isolation by distance [IBD]) and environmental (isolation by environment [IBE]) distance for ex situ collections for which population provenance is available. We used 19 genetic and genomic data sets from 15 plant species to assess the proportion of population genetic differentiation explained by geographic and environmental factors and to simulate ex situ collections prioritizing source populations based on pairwise geographic distance, environmental distance, or both. Specifically, we tested the impact prioritizing sampling based on these distances may have on the capture of neutral, functional, or putatively adaptive genetic diversity and differentiation. Individually, IBD and IBE explained limited population genetic differences across all 3 genetic marker classes (IBD, 10–16%; IBE, 1–5.5%). Together, they explained a substantial proportion of population genetic differences for functional (45%) and adaptive (71%) variation. Simulated ex situ collections revealed that inclusion of IBD, IBE, or both increased allelic diversity and genetic differentiation captured among populations, particularly for loci that may be important for adaptation. Thus, prioritizing population collections based on environmental and geographic distance data can optimize genetic variation captured ex situ. For the vast majority of plant species for which there is no genetic information, these data are invaluable to conservation because they can guide preservation of genetic variation needed to maintain evolutionary potential within collections.