The influence of degree of substitution on blend miscibility and biodegradation of cellulose acetate blends

In this account, we report our findings on blends of cellulose acetate having a degree of substitution (DS) of 2.49 (CA2.5) with a cellulose acetate having a DS of 2.06 (CA2.0). This blend system was examined over the composition range of 0–100% CA2.0 employing both solvent casting of films (no plasticizer) and thermal processing (melt-compressed films and injection molding) using poly(ethylene glycol) as a common plasticizer. All thermally processed blends were optically clear and showed no loss in optical quality after storage for several months. Thermal analysis and measurement of physical properties indicate that blends in the middle composition range are partially miscible, while those at the ends of the composition range are miscible. We suggest that the miscibility of these cellulose acetate blends is influenced primarily by the monomer composition of the copolymers. Bench-scale simulated municipal composting confirmed the biodestructability of these blends and indicated that incorporation of a plasticizer accelerated the composting rates of the blends.In vitro aerobic biodegradation testing involving radiochemical labeling conclusively demonstrated that both the lower DS CA2.0 and the plasticizer significantly enhanced the biodegradation of the more highly substituted CA2.5.While this work was in progress, Robert Gardner was struck with cancer and died on June 6, 1995. This paper is dedicated to his memory and to his contributions as a friend and colleague.     

Book reviews

Earth Politics. Ernst Ulrich von Weizsacker, 1994, London, Zed Books, 234 pp. ISBN 1 85649 174 9, pb £14.95; hb £36.95

Greening Your Local Authority. Janice Morphet (Ed.), 1994, London, Pitman Publishing (originally Harlow, Longman), 144 pp. ISBN 0582 229 065, pb £32.50

Ecology and Society: an introduction. Luke Martell, 1994 London, Polity Press, 250 pp. ISBN 0 7456 1022 6, hb £39.50, ISBN 0 7456 1023 4, pb £11.95

The Politics of the Environment. Robert E. Goodin, 1994. Cheltenham, Edward Elgar, 599 pp. ISBN 1 85278 872 0, hb £115.00

Introduction to Environmental Impact Assessment John Glasson, Riki Therivel & Andrew Chadwick, 1994, London, UCL Press, 352 pp. ISBN 1 85728 117 9, hb £45.00, ISBN 1 85728 118 7, pb £14.95

Planning for the Planet: sustainable development strategies for local and strategic plans. Friends of the Earth, 1994, London, FoE, 104 pp. ISBN 1 85750 224 8, £12.00

Environmental Strategy and Sustainable Development: the corporate challenge for the 21st century. Richard Welford, 1995, London, Routledge, 240 pp. ISBN 0 415 10551 X, hb £40.00, ISBN 0 415 10552 8, pb £12.99

Housing and the Environment: a new agenda. Mark Bhatti, Jane Brooke & Mike Gibson (Eds), 1994, Foreword by Jonathon Porritt, Coventry, Chartered Institute of Housing, 210 pp. ISBN 0 901 607 738, £14.95     

Considerations for Manufacturing Bio-Based Plastic Products

One engine that drives the United States’ economic growth is an ever-increasing demand for manufactured products, both at home and abroad. This increase has created a major concern for the environment in terms of disposing used goods and ensuring that these products are safe. As environmental concerns grow, however, renewable resources are gaining increasing attention, especially as industrial ecology and product biodegradability gain importance. Added to this, biological materials are increasingly being utilized to replace traditional materials in manufacturing. To aid both educators as well as researchers, this paper examines several considerations that are essential for manufacturing plastic products that contain biomaterials. These include the selection of materials, the selection of manufacturing processes, manufacturing costs, and the quality of final products. Additionally, several standard methods that are commonly used for the determination of mechanical and physical properties are compiled; thus this paper should be a useful resource for both educators and researchers. The trends discussed here and their implications are critical for those involved in manufacturing, because contrary to conventional wisdom, simultaneously meeting the material production needs of our society, as well as that of the environment are not mutually-exclusive.     

Impact of Land Use on Soluble Organic Nitrogen in Soil

Although it has been hypothesized that soluble organic nitrogen (SON) plays a central role in regulating productivity in some terrestrial ecosystems, the factors controlling the size of the SON pool in soil remain poorly understood. Therefore our principal aim in this work was to assess the impact of seven different land use systems (rough and managed grassland, deciduous and coniferous woodland, heathland, wetland and tilled land) on the size of the SON and inorganic N (NO ₃ ^– , NH ₄ ⁺ ) pools in the surface soil layer (0–15 cm). After extraction with deionised water, we found that in most cases the size of the water extractable organic N (WEON) pool was similar in size to the inorganic N pool. In contrast, the KCl extractable organic N (KClEON) pool constituted the dominant form of soluble N in soils under all land uses, perhaps indicating that significant amounts were held on the soil exchange phase. In contrast to inorganic N, which varied significantly with land use, the size of the KClEON and WEON pool was similar for all land uses with the exception of KClEON in tilled land, where significantly lower amounts were observed. We conclude that SON constitutes an important soil N pool in a broad range of land uses, and that its role in microbial N assimilation, plant nutrition and ecosystem responses to atmospheric N deposition warrants further attention. SAFRD, University of Newcastle, Newcastle-upon-Tyne, NE1 7RU, U.K.     

An assessment of Mississippi's nonindustrial private forest landowners knowledge of forestry BMP's

This study examined the knowledge levels of Mississippi Non Industrial Private Forest (NIPF) landowners. Data were collected by passing out surveys to participants in Best Management Practices (BMP) educational programs held in conjunction with County Forestry Association (CFA) meetings across Mississippi. Ten CFA's participated in this study. Educational program participants were asked to fill out a survey with several demographic and BMP questions prior to the educational program. Results show that BMP program participants owned an average of 113 hectares, whereas the average Mississippi NIPF landowner owns 20 hectares. Responses to BMP related questions show that Mississippi NIPF landowners have a low level of knowledge concerning BMP's. This situation is likely similar to other states in the Southeastern United States. It can be assumed that county forestry association members are more active and informed about managing their forest land. Therefore, these results may overestimate the BMP knowledge level all landowners in Mississippi.Improved educational programs for NIPF landowners, along with better communication between foresters, loggers, and NIPF landowners are needed if BMP's are to be implemented effectively in Mississippi and across the southern region.     

Spatial prioritization of revegetation sites for dryland salinity management: an analytical framework using GIS

To address the limited application of analytical and modelling techniques in prioritizing revegetation sites for dryland salinity (saline land) management, a case study of the Hodgson Creek catchment in Queensland, Australia, was conducted. An analytical framework was developed, incorporating the use of spatial datasets (Landsat 7 image, DEM, soil map, and salinity map), which were processed using digital image processing techniques and a geographic information system (GIS). Revegetation sites were mapped and their priority determined based on recharge area, land use/cover and sub‐catchment salinity. The analytical framework presented here enhances the systematic use of land information, widens the scope for scenario testing, and improves the testing of alternative revegetation options. The spatial patterns of revegetation sites could provide an additional set of information relevant in the design of revegetation strategies.     

A Quantitative Tool for Assessing the Integrity of Southern Coastal California Streams

We developed a benthic macroinvertebrate index of biological integrity (B-IBI) for the semiarid and populous southern California coastal region. Potential reference sites were screened from a pool of 275 sites, first with quantitative GIS landscape analysis at several spatial scales and then with local condition assessments (in-stream and riparian) that quantified stressors acting on study reaches. We screened 61 candidate metrics for inclusion in the B-IBI based on three criteria: sufficient range for scoring, responsiveness to watershed and reach-scale disturbance gradients, and minimal correlation with other responsive metrics. Final metrics included: percent collector-gatherer + collector-filterer individuals, percent noninsect taxa, percent tolerant taxa, Coleoptera richness, predator richness, percent intolerant individuals, and EPT richness. Three metrics had lower scores in chaparral reference sites than in mountain reference sites and were scored on separate scales in the B-IBI. Metrics were scored and assembled into a composite B-IBI, which was then divided into five roughly equal condition categories. PCA analysis was used to demonstrate that the B-IBI was sensitive to composite stressor gradients; we also confirmed that the B-IBI scores were not correlated with elevation, season, or watershed area. Application of the B-IBI to an independent validation dataset (69 sites) produced results congruent with the development dataset and a separate repeatability study at four sites in the region confirmed that the B-IBI scoring is precise. The SoCal B-IBI is an effective tool with strong performance characteristics and provides a practical means of evaluating biotic condition of streams in southern coastal California.     

The acetochlor registration partnership surface water monitoring program for four corn herbicides

A surface drinking water monitoring program for four corn (Zea mays L.) herbicides was conducted during 1995-2001. Stratified random sampling was used to select 175 community water systems (CWSs) within a 12-state area, with an emphasis on the most vulnerable sites, based on corn intensity and watershed size. Finished drinking water was monitored at all sites, and raw water was monitored at many sites using activated carbon, which was shown capable of removing herbicides and their degradates from drinking water. Samples were collected biweekly from mid-March through the end of August, and twice during the off-season. The analytical method had a detection limit of 0.05 microg L(-1) for alachlor [2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl)-acetamide] and 0.03 microg L(-1) for acetochlor [2-chloro-N-(ethoxymethyl)-N-(2-ethyl-6-methylphenyl)-acetamide], atrazine [6-chloro-N-ethyl-N'-(1-methylethyl)-1,3,5-triazine-2,4-diamine], and metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)-acetamide]. Of the 16528 drinking water samples analyzed, acetochlor, alachlor, atrazine, and metolachlor were detected in 19, 7, 87, and 53% of the samples, respectively. During 1999-2001, samples were also analyzed for the presence of six major degradates of the chloroacetanilide herbicides, which were detected more frequently than their parent compounds, despite having higher detection limits of 0.1 to 0.2 microg L(-1). Overall detection frequencies were correlated with product use and environmental fate characteristics. Reservoirs were particularly vulnerable to atrazine, which exceeded its 3 microg L(-1) maximum contaminant level at 25 such sites during 1995-1999. Acetochlor annualized mean concentrations (AMCs) did not exceed its mitigation trigger (2 microg L(-1)) at any site, and comparisons of observed levels with standard measures of human and ecological hazards indicate that it poses no significant risk to human health or the environment.     

Species diversity or biodiversity?

Species diversity and biodiversity are widely used terms in ecology and natural resource management. Despite this, they are not easily defined and different authors apply these terms with varying connotations. The term biodiversity, in particular, has the dubious honour of being widely used but rarely defined. Is it simply the number of species or is it something more? Here I consider what these terms might really mean and their value. I also briefly discuss the rationale for studying and protecting species diversity or biodiversity.     

Contaminant mass flux and forensic assessment of polycyclic aromatic hydrocarbons: Tools to inform remediation decision making at a contaminated site in Canada

Polycyclic aromatic hydrocarbons (PAHs) and metal(loid) mass flux estimates and forensic assessment using PAH diagnostic ratios were used to inform remediation decision making at the Sydney Tar Ponds (STPs) and Coke Ovens cleanup project in eastern Canada. Environmental effects monitoring of surface marine sediments in Sydney Harbor indicated significantly higher PAH concentrations during the first year of remediation monitoring compared to baseline. This was equivalent to PAH loadings of ～2,000 kg over a 15‐month period. Increases in sediment PAH concentrations raised serious concerns for regulators, who requested cessation of remediation activities early in the $400 M (CAD) project. Historically, the STPs were reported as the primary source of PAH contamination in Sydney Harbor with estimated discharges of 300 to 800 kg/year between 1989 and 2001. Mass flux estimates of PAHs and metal(loid)s and PAH diagnostic ratios were used to evaluate if increases in PAH concentrations in marine sediments were the result of the STPs remediation activities. PAH mass flux estimates approximated that 17 to 97 kg/year were discharged from the STPs during three years of remediation and were corroborated by an independent PAH flux estimate of 119 kg in year 1. PAH fluxes to the Sydney Harbor were mostly surface water derived, with groundwater contributing negligible quantities (0.002–0.005 kg/year). Fluxes of metal(loid)s to harbor sediments were stable or declining across all years and were mirrored in sediment metal(loid) concentrations, which lacked temporal variation, unlike total PAH concentrations. Flux results were also corroborated using PAH diagnostic ratios, which found a common source of PAHs. Coal combustion was likely the principal source of PAHs and not migration from the STPs during remediation. Although short‐term residual sediment PAH increases during onset of remediation raised concerns for regulators, calls for premature cessation of remediation early in the project were unwarranted based on only one year of monitoring data. Mass flux estimates and forensic assessments using PAH diagnostic ratios proved useful tools to inform remediation decision making that helped environmental protection and reduced costs associated with lost cleanup time.