Relationships between dairy slurry total solids, gas emissions, and surface crusts

Livestock slurry storages are sources of methane (CH?), nitrous oxide (NO?), and ammonia (NH?) emissions. Total solids (TS) content is an indicator of substrate availability for CH? and N?O production and NH? emissions and is related to crust formation, which can affect these gas emissions. The effect of TS on these emissions from pilot-scale slurry storages was quantified from 20 May through 16 Nov. 2010 in Nova Scotia, Canada. Emissions from six dairy slurries with TS ranging from 0.3 to 9.5% were continuously measured using flow-through steady-state chambers. Methane emissions modeled using the USEPA methodology were compared with measured data focusing on emissions when empty storages were filled, and retention times were >30 d with undegraded volatile solids (VS) remaining in the system considered available for CH? production (VS carry-over). Surface crusts formed on all the slurries. Only the slurries with TS of 3.2 and 5.8% were covered completely for ～3 mo. Nitrous oxide contributed <5% of total greenhouse gas emissions for all TS levels. Ammonia and CH? emissions increased linearly with TS despite variable crusting, suggesting substrate availability for gas production was more important than crust formation in regulating emissions over long-term storage. Modeled CH? emissions were substantially higher than measured data in the first month, and accounting for this could improve overall model performance. Carried-over VS were a CH? source in months 2 through 6. The results of this study suggest that substrate availability regulates emissions over long-term storage and that modifying the USEPA model to better describe carbon cycling is warranted.     

Community Sustainability Plans to enable change towards sustainable practice – a Scottish case study

There is a need for a global shift towards a low-carbon society and this requires action at the local level. The aim of the study into sustainable community development is to clarify the role of a community as a whole rather than the role of individuals within that community. Mixed methods of literature review and empirical study have been used to translate the knowledge and experience with urban sustainable development into empirical knowledge of a rural, market town setting. The exemplary case study is the Scottish market town Huntly. The main findings of the study show the need for three ingredients for a Community Sustainability Plan for a town such as Huntly. Community involvement is crucial in developing such plans in a rural setting. Further research in more remote settings, e.g. coastal and island communities, is needed to allow broader conclusions on rural sustainable development.     

Metal capital sustaining a North American city: Iron and copper in New Haven, CT

A detailed inventory shows that an average resident of the City of New Haven depends on a per capita capital stock of 9200 kg/c of iron and 144 kg/c of copper in the city infrastructure, buildings, transportation systems, and equipment. Of the iron stock 28% is in items such as rail cars and ships in ocean trade not permanently within the city, and 22% is devoted to receiving and delivering oil fuel to the city and its surrounding communities. Copper is principally used in the distribution of electric power and in water piping within buildings. The city's 9200 kg/c of iron stock-in-use is less than the 13,000 kg/c national average due to New Haven's lack of heavy industry and relatively small number of large buildings. The 144 kg/c of copper stock-in-use is only 58% of the overall value for the United States, but is comparable to that in cities such as Stockholm, Sweden. Attainment of a level of iron and copper services with contemporary technology in less developed countries to the level enjoyed in New Haven would require consumption of the presently identified world copper resources.     

Baseflow nitrate in relation to stream order and agricultural land use

Management of agricultural nonpoint-source pollution continues to be a challenge because of spatial and temporal variability. Using stream order as an index, we explored the distribution of nitrate concentration and load along the stream network of a large agricultural watershed in Pennsylvania-the East Mahantango Creek Watershed and two of its sub-watersheds. To understand nitrate concentration variation in the stream water contributed from ground water, this study focused on baseflow. Impacts of agricultural land use area on baseflow nitrate in the stream network were investigated. Nitrate concentration showed a general decreasing trend with increasing stream order based on stream order averaged values; however, considerable spatial and temporal variability existed within each snapshot sampling. Nitrate loads increased with stream order in a power function because of the dominant effect of stream flow rate over the nitrate concentration. Within delineated sub-watersheds based on stream orders, positive linear functions were found between agricultural land use area percentage and the baseflow nitrate concentration and between agricultural drainage area and the nitrate load. The slope of the positive linear regression between the baseflow nitrate concentration and percent agricultural land area seems to be a valuable indicator of a watershed's water quality as influenced by agricultural practices, watershed size, and specific physiographic setting. Stream order seems to integrate, to a certain degree, the source and transport aspects of nonpoint-source pollution on a yearly averaged basis and thus might provide a quick estimate of the overall trend in baseflow nitrate concentration and load distribution along complex stream networks in agricultural watersheds.     

EVALUATION OF PROBABILITY DENSITY FUNCTIONS IN PRECIPITATION MODELS FOR THE PACIFIC NORTHWEST1

ABSTRACT: Recent work has found that a one-parameter Weibull model of wet day precipitation amount based on the Weibull distribution provides a better fit to historical daily precipitation data for eastern U.S. sites than other one-parameter models. The general two-parameter Weibull distribution was compared in this study to other widely used distributions for describing the distribution of daily precipitation event sizes at 99 sites from the U.S. Pacific Northwest. Surprisingly little performance was sacrificed by reducing the two-parameter Weibull to a single-parameter distribution. Advantages of the single-parameter model included requiring only the mean wet day precipitation amount for calibration, invertibility for simulation purposes, and ease of analytical manipulation. The fit of the single-parameter Weibull to the 99 stations included in this study was significantly better than other single-parameter models tested, and performed as well as the widely endorsed, more cumbersome, two-parameter gamma model. Both the one-and two-parameter Weibull distributions are shown to have b-moments that are consistent with historical precipitation data, while the ratio of b-skew and b-variance in the gamma model is inconsistent with the historical recerd by this measure. In addition, it was found that the two-parameter gamma distribution was better fit using the method of moments estimators than maximum likelihood estimates. These findings suggested that the distribution in precipitation among sites in the Pacific Northwest with dramatically different settings are nearly identical if expressed in proportion to the mean site event size.     

Using the paired comparison methodology to assess environmental values in the coastal zone of Ghana

Like many developing countries, Ghana is grappling with environmental issues, such as the degradation of coastal natural resources. In an attempt to ameliorate the current state of affairs, broad institutional arrangements and policy interventions have been put in place. However coastal natural resources are still being overexploited and the effects of this are felt more strongly by certain groups (such as women and the rural poor) than others. This has led to the argument pointing to an urgent need to include local resource users as active participants in environmental decision making and to incorporate their environmental values in the management of coastal natural resources. Using empirical data from women in two Ghanaian coastal communities, this paper highlights the importance of exploring how the environmental attitudes and values of women might be considered in the management of local coastal natural resources. It assesses effectiveness of the paired comparison methodology in this respects and how this method can be also used to prioritise their environmental concerns. The results show that in both areas respondents place the greatest importance on the coastal natural resources as sources of wealth creation and of food, values which are often described as being “anthropocentric”. The paper thus argues that having discovered that the ecological value placed on natural resources is low, initiatives that could win the support of people would be those that link the livelihood and wellbeing to coastal NRM. It emphasizes the fact that conservation cannot exist outside of people and social systems; nor will it succeed unless they are linked to the welfare of resource users.     

Solitary behavior in a high-altitude population of the social sweat bee Halictus rubicundus (Hymenoptera: Halictidae)

In the subalpine region of the Rocky Mountains of Colorado, United States, Halictus rubicundus has a solitary life cycle, but it is social in other parts of its known range. The brood is protandrous, with a nearly equal investment in the sexes. Productivity averages 6.5 offspring per foundress female, similar to the second brood of social nests in New York, but less than the combined productivity of both New York broods. Leucophora sp. (Diptera: Anthomyiidae) is the principal cause of brood mortality in Colorado. Foundress females in about half the nests survive until brood emerge as adults. Retention of these foundresses decreases offspring mortality by 68%. Comparable abilities to express solitary behavior with a single brood may characterize other eusocial halictine lineages that have successfully invaded high altitudes in the Rocky Mountains. The apparent inability to do this may help explain the absence of other eusocial halictine bees and polistine wasps at high altitudes, despite their success at lower elevations in the same mountains. Presence or absence of this ability may help explain latitudinal distributions of these lineages in North America. Holarctic distributions of lineages with eusocial behavior can be explained by migration as solitary populations from Eurasia to North America across Pleistocene Bering land bridges, with re-expression of double-brooded, eusocial behavior when the species then extended their ranges southward in North America. Received: 4 November 1994/Accepted after revision: 23 October 1995