Composting of miscible cellulose acetate propionate-aliphatic polyester blends

A series of miscible blends consisting of cellulose acetate propionate (CAP) and poly(ethylene glutarate) (PEG) or poly(tetramethylene glutarate) (PTG) were evaluated in a static bench-scale simulated municipal compost environment. Samples were removed from the compost at different intervals, and the weight loss was determined before evaluation by gel permeation chromatography, scanning electron microscopy, and¹H NMR. The type of polyester (PEG versus PTG) in the blend made no difference in composting rates. At fixed CAP degree of substitution (DS), when the content of polyester in the blend was increased, the rate of composting and the weight loss due to composting increased. When the CAP was highly substituted, little degradation was observed within 30 days and almost all of the weight loss was ascribed to loss of polyester. Although the polyester was still observed to degrade faster, when the CAP DS was below approximately 2.0, both components are observed to degrade. The data suggests that initial degradation of the polyester is by chemical hydrolysis and the rate of this hydrolysis is very dependent upon the temperature profile of the compost and upon the DS of the CAP.     

Respiratory and behavioral responses of the grass shrimp Palaemonetes pugio to cadmium and reduced dissolved oxygen

Adult grass shrimp (Palaemonetes pugio) were collected during July and August, 1973, and exposed for 48-h periods to a series of sublethal cadmium (Cd) concentrations: 0.1 and 0.56 mg l^-1 for metabolic studies; and 0.01, 0.05, 0.1, 0.3, 0.56 mg l^-1 for locomotor studies. Treatment effects were tested singly and in combination at selected dissolved oxygen (DO) concentrations ranging from near saturation to 0.8 mgl^-1. Shrimp not exposed to Cd exhibited metabolic regulation between 6.5 and, 4.6 mg DOl^-1, with progressively lower O₂ consumption rates at lower DO concentrations. Oxygen consumption of Cd-exposed shrimp was suppressed overall relative to the non-Cd treated shrimp, and with one exception, the magnitude of metabolic suppression directly corresponded to Cd concentration. Locomotor activity of non-Cd exposed shrimp was relatively independent of DO concentration down to 2.8 mg DO l^-1 and became significantly suppressed at 1.8 mg DO l^-1 and below. Significant suppression of locomotion was evident in shrimp exposed to 0.56 mg Cd l^-1, but was not seen in treatment groups of 0.3 mg Cd l^-1 or lower. No interaction on locomotor activity of shrimp was detected between Cd exposure and oxygen concentration. The reduction of locomotor activity and metabolism at 0.56 mg Cd l^-1 exposure is similar to that occurring under reduced oxygen condition. It is hypothesized that Cd acts in some manner to suppress O₂ availability to P. pugio, a suggestion consistent with literature reports on adverse effects of Cd on fish respiratory enzymes and gill tissue.Contribution No. 351 of the U.S. Environmental Protection Agency, Environmental Research Laboratory, Narragansett, Rhode Island. Although the research described in this article was funded by the U.S. Environmental Protection Agency, it has not been subjected to Agency review and therefore does not necessarily reflect the views of the Agency and no official endorsement should be inferred     

The current and future management of wild mammals hunted with dogs in England and Wales

There is increasing concern about the use of lethal methods to control wild mammal populations, especially those methods that may have significant impacts on animal welfare. The continued use of dogs to hunt wild mammals in England and Wales, principally foxes (Vulpes vulpes), red deer (Cervus elaphus), brown hares (Lepus europaeus) and mink (Mustela vison), has become a focus for political debate and has been the subject of a recent UK government inquiry. This paper reports the results of a questionnaire study to quantify the use, effectiveness and acceptability of the different methods currently used to manage these four species, and future changes in management following a possible ban on hunting with dogs. There was no straightforward relationship between culling pressure and perceived pest status of the different species from the questionnaire data. For foxes and brown hares, the proportion of land managers (practitioners) carrying out lethal control was higher than that considering these species to be pests. However, the reverse was the case for mink. The most frequently used and effective control methods, which were most acceptable to practitioners and public alike, were various forms of shooting. The general public perceived hunting with dogs as one of the least acceptable means of control for all four species. Practitioners thought that hunting with dogs for red deer and the use of terriers against foxes were among the least acceptable forms of control, but considered hunting with dogs in other situations and for other species to be relatively acceptable. Most practitioners said a ban on hunting with dogs would make no difference to their management of the four species. A ban on hunting with dogs would have minimal impact on populations of foxes, red deer and mink, but it may be of conservation benefit to hares.     

Modelling the compression behaviour of landfilled domestic waste

This paper discusses the mechanisms involved in the compression of domestic waste, and how the resulting compression behaviour may be modelled. Reference is made to experimental data illustrating the effect of gas content and pore water pressure on bulk density and drainable porosity, and a theoretical model able to reproduce some but not all features of the data is presented.     

Shifting Lands: Exploring Kansas Farmer Decision-Making in an Era of Climate Change and Biofuels Production

While farming has been the subject of frequent critical analysis with respect to its environmental impacts, including its greenhouse gas emissions, there has been relatively little consideration of the potentially positive role of agriculture in responding to a future greatly influenced by climate change. One possible realm for agriculture to contribute successfully to this future is through biofuels cultivation. This paper uses the state of Kansas as an example to examine factors that are influencing farmer decision-making during a time of heightened debates about climate and energy. Drawing on interviews with key informants and Kansas farmers, we apply and refine a conceptual model for understanding farmer decisions. We find that farmers have largely positive perceptions of the natural environment. Climate change, especially, is not a salient concern at this time. Factors that appear most likely to influence farmer decisions to adopt a new practice include the relative advantage of that practice and the ability to learn about and discuss it through existing social networks. Successful policy incentives must provide farmers with a continued sense of both independence and contribution to greater societal good.     

Response of turf and quality of water runoff to manure and fertilizer

Manure applications can benefit turfgrass production and unused nutrients in manure residues can be exported through sod harvests. Yet, nutrients near the soil surface could be transported in surface runoff. Our research objective was to evaluate responses of bermudagrass [Cynodon dactylon (L.) Pers. var. Guymon] turf and volumes and P and N concentrations of surface runoff after fertilizer or composted manure applications. Three replications of five treatments were established on a Boonville fine sandy loam (fine, smectitic, thermic Vertic Albaqualf) that was excavated to create an 8.5% slope. Manure rates of 50 and 100 kg P ha(-1) at the start of two monitoring periods were compared with P fertilizer rates of 25 and 50 kg ha(-1) and an unfertilized control. Compared with initial soil tests, nitrate concentrations decreased and P concentrations increased after two manure or fertilizer applications and eight rain events over the two monitoring periods. The fertilizer sources of P and N produced 19% more dry weight and 21% larger N concentrations in grass clippings than manure sources. Yet, runoff volumes were similar between manure and fertilizer sources of P. Dissolved P concentration (30 mg L(-1)) in runoff during a rain event 3 d after application of 50 kg P ha(-1) was five times greater for fertilizer than for manure P. Observations during both monitoring periods indicated that total P and N losses in runoff were no greater for composted manure than for fertilizer sources of P at relatively large P rates on a steep slope of turfgrass.     

Agro-climatic classification systems for estimating the global distribution of livestock numbers and commodities.

Investment in agricultural research in developing countries is being increasingly targeted at those agro-climatic zones and issues where the economic and environmental benefits may be expected to be greatest. This first requires that the zones themselves be defined, along with information on domestic livestock numbers and commodity output within agro-climatic zones in different countries. Different methods for classifying agro-climatic zones were compared. These included methods based on estimated length of growing period (LGP) using rainfall and temperature data, the ratio of precipitation to potential evapotranspiration (PET), and on more detailed agronomic models, remote sensing data and land use information. Zonation based on LGP has already been linked to existing national livestock data. By defining agro-climatic zones and relating concentrations of livestock populations to those of humans, it is possible to make realistic estimates of livestock populations and the production of livestock commodities for most developing countries. Detailed agro-climatic analyses of Mainland East Asia and Sri Lanka have recently been undertaken using the GROWEST agronomic model. Using this model as the basis of agro-climatic classification appears to be significantly superior, particularly in temperate environments, to approaches based solely on LGP. Different ways of subdividing countries and continents into agro-climatic or agro-ecological zones (AEZs) are reviewed in this paper. In addition, we show how the numbers of production and commodities from domestic livestock can be allocated to such zones. We also indicate how some of this information can be applied.     

A Critical Appraisal of Field Evidence From A Regional Survey for Acid Deposition Effects On Scottish Moorland Podzols

Samples have been collected from major horizons of 34 podzol profiles distributed throughout Scotland, all developed from granite or granitic tills and under Calluna moorland. the pH in water and calcium chloride pastes, exchangeable cations and cation exchange capacity, and extractable aluminium of the soils collected have been measured, and the results studied in relation to reported atmospheric deposition of H⁺, non-marine sulphur and nitrate. for all horizons, significant positive correlations were found between soil pH and rainfall mean pH, as might be expected when the critical load of H⁺ deposition is exceeded. Acidifying pollutant deposition also apparently increased soil extractable aluminium concentrations in the B and C horizons. However, exchangeable base cation concentrations tended to increase, rather than decrease, with increasing precipitation acidity. This effect was attributed to increases in biogeochemical cycling of base cations, increases in leaching inputs of base cations from overlying A/E horizon soils, and increases in the inputs of base cations leached from upslope. the results suggest that the simple steady state mass approach to the quantification of critical loads, as often applied, may be an oversimplification.