Organic agriculture and nitrous oxide emissions at sub-zero soil temperatures

In the Red River Valley of the upper midwestern United States, soil temperatures often remain below freezing during winter and N2O emissions from frozen cropland soils is assumed to be negligible. This study was conducted to determine the strength of N2O emissions and denitrification when soil temperatures were below zero for a manure-amended, certified organic field (T2O) compared with an unamended, conventionally managed field (T2C). Before manure application, both fields were similar with respect to autotrophic and heterotrophic N2O production and N2O flux at the soil surface (0.15+/-0.05 mg N2O-N m-2 d-1 for T2O and 0.12+/-0.06 mg N2O-N m-2 d-1 for T2C). After application of pelletized, dehydrated manure, average daily flux (based on time-integrated fluxes from 20 November to 8 April), was 1.19+/-0.34 mg N2O-N m-2 d-1 for T2O and 0.47+/-0.37 mg N2O-N m-2 d-1 for T2C. Denitrification for intact cores measured in the laboratory at -2.5 degrees C was greater for organically managed soils, although only marginally significant (p<0.1). Cumulative emissions for all winter measurements (from 16 November to 8 April) averaged 1.63 kg N2O-N ha-1 for T2O and 0.64 kg N2O-N ha-1 for T2C. Biological N2O production was evident at sub-zero soil temperatures, with winter emissions exceeding those measured in late summer. Late autumn manure application enhanced cumulative N2O-N emissions by 0.9 kg ha-1.     

HYDROLOGIC LANDSCAPES ON THE DELMARVA PENINSULA PART 1: DRAINAGE BASIN TYPE AND BASE-FLOW CHEMISTRY1

ABSTRACT: The relation between landscape characteristics and water chemistry on the Delmarva Peninsula can be determined through a principal-component analysis of basin characteristics. Two basin types were defined by factor scores: (1) well-drained basins, characterized by combinations of a low percentage of forest cover, a low percentage of poorly drained soil, and elevated channel slope; and (2) poorly drained basins, characterized by a combinations of an elevated percentage of forest cover, an elevated percentage of poorly drained soil, and low channel slopes. Results from base-flow sampling of 29 basins during spring 1991 indicate that water chemistry of the two basin types differ significantly. Concentrations of calcium, magnesium, potassium, alkalinity, chloride, and nitrate are elevated in well-drained basins, and specific conductance is elevated. Concentrations of aluminum, dissolved organic carbon, sodium, and silica are elevated in poorly drained basins whereas specific conductance is low. The chemical patterns found in well-drained basins can be attributed to the application of agricultural chemicals, and those in poorly drained basins can be attributed to ground-water flowpaths. These results indicate that basin types determined by a quantitative analysis of basin characteristics can be related statistically to differences in base-flow chemistry, and that the observed statistical differences can be related to major processes that affect water chemistry.     

Sediment Availability and Erosion Rates on Off‐Highway Vehicle Trails in the Ouachita Mountains,USA

Factors influencing sediment availability are assessed and erosion rates are quantified for an off‐highway vehicle (OHV) trail system in the Ouachita Mountains of Arkansas. As of May 2012, the Wolf Pen Gap trail system included 77.0 km of "trails" which consist of county roads; open and closed Forest Service roads; and open and closed OHV trails. For a given trail length, the sediment volume available to be eroded is determined by bare trail width and sediment depth. Four condition types are defined that group trail sections based on statistically different trail widths or depths. Trail construction method appears to influence sediment availability differences more than erosion potential (as indexed by trail slope gradient and length). The range for annual trail erosion rates is estimated as 75 and 210 tonne/ha/yr. The high and low rates are obtained using two independent methods. The 210 tonne/ha/yr rate is computed from mean sediment capture at 30 sediment traps installed for 0.5–1.0 year. The 75 tonne/ha/yr rate is computed assuming all available trail sediment measured in a one‐time sampling is eroded over the next year. We argue in support of this assumption and suggest both rate values may be conservative. Trail erosion rates and sediment trap observations indicate frequent trap cleanout will be needed to continue sediment capture from All Terrain Vehicle trails.     

Economic appraisal and evaluation of UK waste minimisation clubs: proposals to inform the design of sustainable clubs

Waste minimisation clubs have been established for some 12 years in the UK. During that time, they have been significant driving forces in disseminating sustainable waste management practices in industry and commerce. Clubs have also demonstrated that they can achieve significant reductions in levels of waste. However, data on the economic benefits of these clubs remain scanty and disparate. In addition, no standard methodology has developed to assess whether the investment costs of clubs can be justified on grounds of either economic welfare or sustainable development, despite the theoretical advantages from doing so. Against this background, the paper considers the need for economic appraisal and evaluation of waste minimisation clubs and discusses how these methods could be applied to the creation of clubs that will be sustainable over time.     

Impact of sample preparation on mineralogical analysis of zero-valent iron reactive barrier materials

Permeable reactive barriers (PRBs) of zero-valent iron (Fe(0)) are increasingly being used to remediate contaminated ground water. Corrosion of Fe(0) filings and the formation of precipitates can occur when the PRB material comes in contact with ground water and may reduce the lifespan and effectiveness of the barrier. At present, there are no routine procedures for preparing and analyzing the mineral precipitates from Fe(0) PRB material. These procedures are needed because mineralogical composition of corrosion products used to interpret the barrier processes can change with iron oxidation and sample preparation. The objectives of this study were (i) to investigate a method of preparing Fe(0) reactive barrier material for mineralogical analysis by X-ray diffraction (XRD), and (ii) to identify Fe mineral phases and rates of transformations induced by different mineralogical preparation techniques. Materials from an in situ Fe(0) PRB were collected by undisturbed coring and processed for XRD analysis after different times since sampling for three size fractions and by various drying treatments. We found that whole-sample preparation for analysis was necessary because mineral precipitates occurred within the PRB material in different size fractions of the samples. Green rusts quickly disappeared from acetone-dried samples and were not present in air-dried and oven-dried samples. Maghemite/magnetite content increased over time and in oven-dried samples, especially after heating to 105 degrees C. We conclude that care must be taken during sample preparation of Fe(0) PRB material, especially for detection of green rusts, to ensure accurate identification of minerals present within the barrier system.     

Effects of knowledge,personal attribution and perception of ecosystem health on depreciative behaviors in the intertidal zone of Pacific Rim National Park and Reserve

Human activities levy a biological cost on ecosystems as resources are accessed and utilized at rates which are often incompatible with inherent ecosystem processes and structures. The recreational impact of humans upon intertidal zones and particularly fucoid algal assemblages is one major threat facing coastal ecosystems. The effect of human values, knowledge and perception in effecting biologically costly behaviors has rarely been examined. We hypothesize that with respect to intertidal zones: (1) Personal attribution and perception of ecosystem resiliency are more important than knowledge in determining the extent of depreciative behaviors individuals engage in, and; (2) Individuals who are uncertain about ecosystem resiliency will behave in a manner consistent with the 'precautionary principle'. We measured the depreciative behavior, and the attitudes and perceptions to ecosystem resilience, of visitors to Wick Headland in Pacific Rim National Park, British Columbia. Attitudes, knowledge, perceptions, and personal attribution were measured using questionnaire survey and structured interviews undertaken in situ. Depreciative behaviors of visitors were discreetly observed and correlated to the questionnaire survey and interview responses. We show that visitors who recorded greater knowledge of intertidal ecology engaged in more depreciative behaviors than visitors recording less knowledge. Visitors who perceived high ecosystem resilience in the intertidal zone engaged in significantly more behaviors eliciting biological cost than those who perceived low ecosystem resilience. Visitors who recorded uncertainty regarding ecosystem resilience engaged in significantly more depreciative behaviors than those who perceived low ecosystem resilience but slightly fewer depreciative behaviors than those who perceived high ecosystem resilience. Personal attribution was inversely correlated to the mean number of depreciative behaviors. We discuss the relevance of these results to the management of intertidal zones and marine protected areas, to multiple use management, the management of visitor impact, and natural resource use.     

English county councils and their agenda for waste minimisation

Minimisation is the top priority of the waste management hierarchy, which is one of the guiding principals for national solid waste management planning throughout the developed world. As such it should be encouraged as a means for reducing wastes which require treatment and disposal, whether they be household, commercial or industrial in source. This paper suggests that minimisation is not being given the necessary policy frameworks or legislation within which to develop in the UK, and questions whether minimisation is being afforded the respect and attention, from all levels, that is due the most preferable waste option according to the hierarchy. This theme is investigated by surveying the county councils of England as a representative sample of waste disposal authorities in England, and former waste regulation authorities. They are responsible for guiding local and district waste policy and are the regional waste planners in the UK. If they are not seriously taking on board the message of minimisation, then there is little chance that it will succeed without further legislative developments. Some 59% of English counties have a minimisation policy, whilst only 47% have participated in and supported a minimisation programme or trial within their region. The majority of these developments have occurred within the last three years, and 78% of counties who have participated in a programme have found it a successful venture. By 1999 79% of English counties will have been actively involved in a minimisation programme in their region, which is a positive scenario. This trend must continue if waste minimisation is to become the key theme of future sustainable waste management in the UK as was intended by declarations at the Rio '92 conference and in subsequent UK Government policy and strategy.