Enrichment of <Superscript>15</Superscript>N/<Superscript>14</Superscript>N in wastewater-derived effluent varies with operational performance of treatment systems: implications for isotope monitoring in receiving environments

Stable nitrogen isotope ratios are routinely used to trace the dispersion and assimilation of wastewater-derived N in receiving environments, but few isotope studies have investigated wastewater treatment plants and ponds themselves. An improved understanding of N isotope compositions in effluent will help assess treatment plant processes and performance and will help trace sources of excess nutrients in receiving environments. Here, we assess N budgets and treatment processes in seven wastewater treatment plants and wastewater stabilisation ponds in northern Australia based on concentrations and isotope ratios of N in effluent. We show that δ¹⁵N values in effluent are linked to treatment type, effectiveness of conversion of ammonia and levels of gaseous N emissions. These relationships suggest that N isotope monitoring of wastewater treatment plants and ponds can provide an integrated assessment of treatment performance and gaseous N emissions on a pond- or plant-wide scale that is not readily available through other methods. Our findings further imply that monitoring N isotope ratios in receiving environments cannot be assumed to be universally effective as their sensitivity to uptake of wastewater-derived N will vary with the characteristics of individual treatment systems. Paradoxically, N isotope monitoring is less effective where treatment systems are functioning poorly and where monitoring needs are the greatest.     

The role of academia in regional sustainability initiatives: Wales

This paper demonstrates the relative non-engagement of universities in regional sustainability initiatives through a case study of Cardiff University in Wales. It is argued that the turbulent and often complicated political and administrative context along with divergent goals and performance targets means that synergies are less readily achieved. A case study of automotive industry alternative technology new cluster development is given to illustrate the arguments. In so doing, the paper presents the view that we need to move beyond mere optimism in order to address fundamental underlying issues.     

Establishment of a cross-European field site network in the ALARM project for assessing large-scale changes in biodiversity

The field site network (FSN) plays a central role in conducting joint research within all Assessing Large-scale Risks for biodiversity with tested Methods (ALARM) modules and provides a mechanism for integrating research on different topics in ALARM on the same site for measuring multiple impacts on biodiversity. The network covers most European climates and biogeographic regions, from Mediterranean through central European and boreal to subarctic. The project links databases with the European-wide field site network FSN, including geographic information system (GIS)-based information to characterise the test location for ALARM researchers for joint on-site research. Maps are provided in a standardised way and merged with other site-specific information. The application of GIS for these field sites and the information management promotes the use of the FSN for research and to disseminate the results. We conclude that ALARM FSN sites together with other research sites in Europe jointly could be used as a future backbone for research proposals.     

Nutrients and heavy metals distribution in thermally treated pig manure.

Ash from pig manure treated by combustion and thermal gasification was characterized and compared in terms of nutrient, i.e., potassium (K), phosphorus (P) and heavy metal, i.e., cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni) and zinc (Zn) contents. Total nutrient and metal concentrations were measured using energy dispersive X-ray fluorescence analysis. Acid (HNO3, H2SO4) and water-extractable concentrations were also measured both in non-classified ash and in selected ash particle size fractions using flame atomic absorption spectrometry and colorimetric spectrometry. Results indicate that ash from gasified manure contained more water-extractable K in comparison with combusted manure whereas the opposite was the case with respect to P. Heavy metals Ni, Cr and Cd were present in higher concentrations in the fine particle size fractions (< 30 microm of particle diameter), whereas K, P, Zn and Cu exhibited higher concentrations in the coarser particle size fractions (> 30 microm).     

LCA of comprehensive pig manure management incorporating integrated technology systems

Increased and intensified pig production has raised the needs for proper management systems of pig manure in order to reduce negative environmental impacts. The objectives of this study were to identify the most significant environmental impacts from pig manure management considering a wide range of impact categories and to determine which integrated technology system at which handling stage can achieve the highest impact reduction. Twelve scenarios applying various treatment, storage and land application systems were developed and compared. Life cycle assessment (LCA) with the aim of capturing the actual consequences of the considered scenarios was selected as the tool for impact quantification. The most important impact categories in this investigation are global warming (GWP), aquatic eutrophication (AEP), respiratory inorganics (RIP), and terrestrial eutrophication (TEP). The two latter impacts, caused by ammonia emissions, have not been widely considered in most of previous LCA studies on pig manure management. The main keys for the effective impact reduction are the integration of treatment technology systems aiming at energy recovery with high nutrient recovery and control of greenhouse gas, ammonia, and nitrate emissions at every handling stage. For GWP and AEP, the anaerobic digestion-based scenario with natural crust storage achieves the highest impact reduction because of high efficiencies in energy and nutrient recovery with restricted emissions of GHG and nitrate. For RIP and TEP, the incineration and thermal gasification based scenarios and the scenario without a treatment system applying the deep injection method yield the highest impact minimisation due to the lowest ammonia emissions. This study further indicates the need to consider all significant impacts to decide the best management options taking into consideration local conditions.     

A historical perspective of Global Warming Potential from Municipal Solid Waste Management

The Municipal Solid Waste Management (MSWM) sector has developed considerably during the past century, paving the way for maximum resource (materials and energy) recovery and minimising environmental impacts such as global warming associated with it. The current study is assessing the historical development of MSWM in the municipality of Aalborg, Denmark throughout the period of 1970 to 2010, and its implications regarding Global Warming Potential (GWP₁₀₀), using the Life Cycle Assessment (LCA) approach. Historical data regarding MSW composition, and different treatment technologies such as incineration, recycling and composting has been used in order to perform the analysis. The LCA results show a continuous improvement in environmental performance of MSWM from 1970 to 2010 mainly due to the changes in treatment options, improved efficiency of various treatment technologies and increasing focus on recycling, resulting in a shift from net emission of 618 kg CO₂-eq. tonne^?1 to net saving of 670 kg CO₂-eq. tonne^?1 of MSWM.     

Identifying Riparian Buffer Effects on Stream Nitrogen in Southeastern Coastal Plain Watersheds

Within the Southeastern (SE) Coastal Plain of the U.S., numerous freshwaters and estuaries experience eutrophication with significant nutrient contributions by agricultural non-point sources (NPS). Riparian buffers are often used to reduce agricultural NPS yet the effect of buffers in the watershed is difficult to quantify. Using corrected Akaike information criterion (AIC_c) and model averaging, we compared flow-path riparian buffer models with land use/land cover (LULC) models in 24 watersheds from the SE Coastal Plain to determine the ability of riparian buffers to reduce or mitigate stream total nitrogen concentrations (TNC). Additional models considered the relative importance of headwaters and artificial agricultural drainage in the Coastal Plain. A buffer model which included cropland and non-buffered cropland best explained stream TNC (R ² = 0.75) and was five times more likely to be the correct model than the LULC model. The model average predicted that current buffers removed 52 % of nitrogen from the edge-of-field and 45 % of potential nitrogen from the average SE Coastal Plain watershed. On average, 26 % of stream nitrogen leaked through buffered cropland. Our study suggests that stream TNC could potentially be reduced by 34 % if buffers were adequately restored on all cropland. Such estimates provide realistic expectations of nitrogen removal via buffers to watershed managers as they attempt to meet water quality goals. In addition, model comparisons of AIC_c values indicated that non-headwater buffers may contribute little to stream TNC. Model comparisons also indicated that artificial drainage should be considered when accessing buffers and stream nitrogen.     

Urban community gardening,social capital,and "integration" – a mixed method exploration of urban "integration-gardening" in Copenhagen,Denmark

ABSTRACT

This study examines a community garden in Copenhagen, Denmark, "The Urban Integration Gardens" that endeavours to strengthen social integration in the local multicultural neighbourhood. The "community" in the gardens is explored, with a focus on how they foster social capital, particularly opportunities for "bridging" social capital. A mixed-methods approach is used, by employing a qualitative analysis of gardeners’ perceptions of "community", diversity and inclusivity, through the lens of "cognitive" social capital, and the meanings the gardeners assign to their experiences, and how they understand their involvement in the gardens. We also examine "structural" dimensions of social capital, involving quantitative data from a questionnaire and data from Statistics Denmark, comparing data concerning socio-demographic backgrounds from gardeners and residents in the local neighbourhood and Copenhagen. Major findings include that the garden generates both bonding and bridging "cognitive" social capital, and the gardeners consistently agreed that the garden has a strong community, and is permeated by diversity and inclusivity. Nonetheless, data from Denmark’s Statistics Office reveal that the garden does not "represent" the diversity in the neighbourhood regarding the distribution of members with a Western/non-Western background, as well as social class. This suggests that endeavours to involve co-citizens with non-Western backgrounds and gardeners with lower social status are restrained by potential structural barriers, which limits the "width" of bridging social capital in the garden.